DLC Report

The Frictional Effects of Diamond-Like-Carbon Deposited on a Substrate via Plasma Enhanced Chemical Vapor Deposition

ContentsTable of Contributions......................................................................................................................1

Introduction and Literature Review...........................................................................................2

DLC History.......................................................................................................................................2

DLC Chemical Properties:........................................................................................................ 4DLC Characteristics......................................................................................................................5

DLC Coating Processes.............................................................................................................7

DLC Applications.........................................................................................................................10

Testing Method Selection............................................................................................................12

Alternative Testing Methods.......................................................................................................13

Ball-on-Flat (Heimberg et al, 2001)...................................................................................13

Laboratory Bench Rig (Gangopadhyay et al, 2011).................................................14

Motored Valvetrain Rig for Friction Evaluations (Gangopadhyay et al, 2011).............................................................................................................................................................. 15

Twin-Disc Testing Rig (Löhr, 2006)...................................................................................16

Methodology....................................................................................................................................... 17

Calculations and Results............................................................................................................. 21

Calculations....................................................................................................................................21

Results:.............................................................................................................................................26

Discussion............................................................................................................................................33

MDF.................................................................................................................................................... 33

Metal Sheet.................................................................................................................................... 35

Comparison.................................................................................................................................... 36

Conclusions and the future of DLC Coating......................................................................38

Project Management - Critical Assessment.......................................................................40

Table of Contributions

Member ContributionAli Maasoumian - Background research on friction

- Literature review over DLC chemical properties- Research over DLC characteristics- Research over DLC applications- Testing set up and optimization

Amandeep Mankoo - Background research on friction- Testing and setup- Research over improvements on current methods- Introduction and conclusion

Joseph Mendonca - Background research on DLC history- Literature review over DLC coating methods- Testing setup and optimization- Report formatting

Mohammed Miah - Background research on testing methods- Testing and data collection- Methodology- Research on DLC future applications- Conclusion and discussions

Nakul Shah - Testing setup assessment- Testing- Data collection and calculations- Data analysis- Discussion

1

Introduction and Literature Review

The optimization of a system is a key aspect in the field of Engineering, with

continuous improvements always being made to combat efficiency, a key component

of energy loss being friction. Many of today’s methods of overcoming frictional losses

are expensive, therefore a cost-effective method of reducing frictional losses is

investigated.

Diamond-like carbon (DLC) coating is a process in which a thin film of diamond-like

carbon is deposited on a substrate in order to improve the physical and chemical

resistance of the base material. This report examines the effect that DLC coating has

on the static and dynamic friction when applied to an industrial adhesive tape, this is

done in an attempt to assess its feasibility, with the overall aim being a

commercialised friction-reducing sticky tape, which can be stuck to a variety of

surfaces. Applications may include the underside of skis and sliding drawers in

domestic or industrial furniture.

DLC HistoryHard amorphous carbon films were first mentioned by Schmellenmeier (1953). In his

investigation, the influence of an ionized acetylene atmosphere on the surfaces of

tungsten-cobalt alloys was investigated using a glow discharge system which is a

plasma formed by the passing of an electric current through a hydrocarbon

atmosphere. The aim of the experiment was to observe if tungsten carbide hard

metal surface layers could be produced. However, it was noticed that a hard

amorphous carbon film was deposited on the cathode of the direct current (DC) glow

discharge system. In a further study performed by Schmellenmeier (1956), it was

found that some of these micrometer thick layers had ‘structure-less’ regions but

others were formed of crystallites; which was identified as diamond by x-ray

diffraction.

The term ‘diamond like carbon’ was first used by Aisenberg and Chabot (1971). The

investigation focused on an ion beam deposition technique, which is the process of

applying a material to a substrate by using ion beams. The ion beam used consisted

on carbon and argon gas and when applied to the substrate, thin carbon films were

deposited on the graphite electrodes. An investigation into the properties of these

films was done and it was found that the coatings had favorable scratch and

chemical resistance as well as electronic insulation whilst being optically transparent.

2

Around this period, other studies into the properties of these amorphous carbon films

were published. Spencer et al (1976) used x-ray diffraction and transmission electron

microscopy to study the structure of these films. The findings supported the research

done by Aisenberg and Chabot as it showed the same crystalline structure but

furthered the understanding by classing these crystalline compositions as either large

or small.

Since the mid 1970s, there have been constant advancements in deposition methods

and the characteristics of these films were characterized in detail. Weissmantel et al

(1977, 1979) reported on 2 different methods for the preparation of DLC coating. The

first is the dual beam technique through which a carbon target was bombarded with

argon ions and the carbon film produced from this was simultaneously bombarded by

a second ion source. The film produced was hard and described as ‘amorphous with

crystallites in the regions exposed to the highest ion densities.’

The second method comprised of using DC hot cathode ionization to generate

hydrocarbon ions in a benzene atmosphere, which bond to a substrate that has a

negative charge bias. The films produced were hard, partially optically transparent

and electrically insulating. Weissmantel and co workers described the material

structure as a mixture of nano-crystalline components consisting of graphite and

diamond like elements.

In the early 1980’s, a new quality that DLC films possess had been discovered. Enke,

Dimigen et al (1980) reported on the friction properties of DLC coatings against steel.

It was found that in contrast to graphite, the DLC films had noticeably lower friction

coefficients, especially under conditions of low humidity.

In the early 1990s work had commenced on manipulating the deposition processes in

order to optimize the properties of the coatings. Martinu et al (1992) worked to

increase the effectiveness of the radio frequency (r.f.) process. This was achieved by

running the process whilst simultaneously operating microwave radiation. The

addition of microwaves increases the ion fluxes on the substrate, which in turn

increases the deposition rate and increases the hardness by reducing the hydrogen

content present in the deposited film.

3

Figure 1: Graph to show the number of publications on DLC between 1970 and 2012

The combination of lower friction and increased hardness and wear resistance has

led to an increase in the number of research groups working with DLC coating

technologies. Figure 1, above, displays this increase in DLC based research

publications since 1970.

DLC Chemical Properties:Diamond Like Carbon (DLC) coating is done through a process of fusion where

carbon atoms are coated over other materials. Typically the carbon layers consist of

two different atomic configurations of sp2 and sp3 with 30-50% sp2 (Graphite) and

50-70% sp3 (Diamond) compositions respectively, as described by Wallwork (2010).

The reasoning behind this is as DLC coating is done through rapid fusion, there is not

sufficient time for crystalline sp3 diamonds to be formed in the initially coated atoms;

hence the first layers consist of sp2 (Graphite) configuration over which the

crystalline structure sp3 (Diamond) configuration will be formed.

Figure 2: Different Carbon states configurations

4

The sp2 configuration in graphite has more softening effects while the crystalline sp3

diamond like configuration makes the material harder. Moreover, when DLC coating

is done over metals such as Titanium, Iron or Steel, the first layer will form carbide

with the metal on which other layers of DLC will form. The formation of carbide has

great effects on making the metal resistant against wear and oxidation.

Furthermore, the sp3 DLC is very resistant to abrasive and adhesive wear which

makes it extremely suitable for applications with high contact pressure, both rolling

and sliding. Added to this, DLC coating makes materials to act as insulators with high

values of resistivity. However, if the DLC is done through cobblestone, the electrons

mat get passed through a mechanism called hoping conductivity of electrons by

quantum mechanical tunneling. This can be used to make the material act as a semi-

conductor.

DLC CharacteristicsAs stated in the previous section, with a large fraction of diamond like sp3 configured

carbons, DLC exhibits many properties associated with diamond such as high values

of hardness and chemical inertness. The former property however is also associated

with the coating process used. This is due the introduction of Hydrogen in some

5

Figure 3: sp3 configuration Figure 4: sp2 configuration

Figure 5: Nanostructure of DLC films

Figure 6: Radial distribution function for DLC

methods of DLC coating for adhesion purposes. DLC coated materials with Hydrogen

yield for lower values of hardness ranging from 15 to 20 GPa according to Weia et al

(1999). In contrast un-Hydrogenated DLC coatings give higher values of hardness

and residual stress compared to Hydrogenated coatings (Residual stress is the

internal stress locked in a material even when it is not under external forces. It is the

result of equilibrium after the material has gone under plastic deformation). In despite

of the obvious benefits of un-Hydrogenated DLC coating, low adhesion factor, which

makes them easily delaminate from a substrate makes is its crucial downside in

comparison with Hydrogenated DLC coating.

In addition to high values of hardness, the smoothness of DLC coating and its tri-

biological properties make it extremely resistant to wear. Furthermore, DLC has very

low value for coefficient of friction (0.04-0.08), which is its prominent feature for use

in industrial applications. Due to its high resistance to abrasive and adhesive wear,

DLC is suitable for applications with extreme contact pressure on both sliding and

rolling surfaces. Furthermore, due to small electron affinity, DLC has high electrical

conductivity, which makes them ideal for different application in electrical industries

as well. However, some DLC coated materials can act as semiconductors through

the mechanism of hoping conductivity Boardman et al (2008). In these materials,

electrons can move by quantum mechanical tunneling, which turns them into

semiconductors.

Added to all this, DLC coating is transparent under infrared light as it follows the

properties of Diamond. It is also biologically inert in contact with other substances.

Further enhancement of the mechanical properties of DLC can be done through

multilayer structure, although complexity and expense may also come into effect. The

following table includes some characteristics and properties of DLC coating.

6

Table 1: DLC characteristics and properties

DLC Coating Processes There are two main categories regarding current DLC coating methods. The first is

known as plasma enhanced chemical vapor deposition (CVD). CVD is the process

through which a substrate is exposed to one or more precursors, which are

compounds that participate in a chemical reaction that produces another compound.

These precursors react and/or decompose on the substrate surface to produce a

desired deposit. The most used format of CVD is plasma enhanced chemical vapor

deposition (PECVD). PECVD is where plasma is introduced to enhance the chemical

reaction rates of the precursors. This allows deposition to occur at much lower

operating temperatures which broadens its usage as the these conditions are

suitable for organic substrates which cannot stand the high temperatures usually

associated with CVD processes. Figure 7 indicates the basic layout of a PECVD

chamber. It can be seen that the plasma fill the chamber as the electric current

passes from the top electrode to the bottom where a substrate is positioned.

7

Composition Typical 30-50% sp2 (Graphitic) Bond / 50-70% sp3 (Diamond) bond. Variable with process

Hardness Microhardness 10-40GPa

Sliding wear rate 5.1E -07mm/Nm2

Coefficient of friction 0.04-0.08 Dependant on substrate surface condition

improved with polished surface

Color Black

Biocompatibility Non Toxic, Non Cyto-Toxic, Non-Gene toxic, Non-

Carcinotoxic

Max operating temperature

400-500oC

Electrical resistance 400-800Wm2/k (1010ΩCm)

Chemical stability Stable in Acids, Alkalis, Solvents and Gas

Figure 7: Schematic of PECVD Chamber

A study was undergone by N. Cuong et al (2003) to investigate DLC films deposited

on polymers by PECVD. The team used a polycarbonate (PC) substrate, which is

thermally stable up to around 190°C. PC has low hardness and demonstrates poor

chemical and physical resistance. N. Cuong et al were able to overcome these poor

qualities by applying an amorphous carbon film to the surface of the polycarbonate.

The PC sample was cleaned with ethanol and dried in a vacuum desiccator. It is then

placed on the lower plate electrode that is cooled by water. This prevents the

substrate exceeding temperatures of 80°C. As a pre-deposition process, the

substrate was bombarded with argon plasma to remove any remaining

contaminations. The deposition process was then undergone with an approximate

deposition rate of 8nm/min. The films produced on the PC substrate were friction

tested using a ball on disk method, which found that hydrogenated carbon films

deposited had a friction coefficient as low as 0.3 as compared to a coefficient of 0.7

of the PC surface. Further work was also done to test resistance against organic

solvents. A drop of acetone was applied to the coating and to the PC surface for a

few seconds. After inspection, it was observed that the untreated surface had been

altered by the reaction whereas the DLC coating was not corroded.

The second categorical method is physical vapor deposition (PVD). This category

describes a variety of methods that use vacuum deposition to deposit thin films by

condensing a vaporized form of the desired coating material. There are several types

of physical vapor deposition such as sputter deposition, which utilizes a glow plasma

8

discharge to eject material from a target which bonds onto a given substrate.

However, the most widely used method of PVD is cathodic arc deposition. This is

where a high-powered electric ‘arc’ is discharged at a cathode material, which blasts

away some material into highly ionized vapor, which can be deposited onto a

substrate. Figure 8 below illustrates this process.

Figure 8: Schematic of cathodic

Takikawa and Tanoue (2007) produced a review of the cathodic arc process. They

specify several different types of arcs that can be used such as a steered arc, which

is most commonly used in industry. A magnetic field is applied on the cathode

surface. This is done in order to avoid overheating of the cathode by keeping it at a

single location and it maintains uniform erosion. The paper highlights the problem

with all different arc types associated with this method; which is the formation of

‘macrodroplets’ that are a secondary emission from the cathode spot. The drops

connect to the film in the preparation and roughen its surface, which therefore

increase the coefficient of friction of the film. As a result of this, any applications of

DLC that utilize the low friction aspect of the material will require the use of CVD

rather than PVD but either method can be used if the application of the film is for

physical and chemical resistance.

9

DLC ApplicationsDLC coating has been associated to make improvements in many applications due to

its profound characteristics which can imply vast developments in fields associated

with high friction and wear, as well as chemical inertness.

Figure 9: Comparison of performance of uncoated, titanium nitride coated and DLC coated drills during stainless steel machining

One of the most prominent applications of DLC coating is in high speed steel

machining and drilling. In recent uses of DLC coating in steel machining it has been

noted that that when DLC coated machines and drills were performed in comparison

with other coated and uncoated machines, they produced fourfold increase in tool’s

life and durability as investigated by Boardman et al (2008). Figure 9 illustrates the

obtained results for Comparison of performance for uncoated, titanium nitride coated

and DLC (~5% Titanium) coated drills during stainless steel machining.

Furthermore, Monaghan et al (1994) performed an investigation and found that

Diamond coatings of machinery tools are the best performing coatings in terms of

performance and durability for Aluminium and Cupper alloys as they provide the least

surface roughness and material waste. However, due to high coating costs of

Diamond, DLC coatings provide the best cost for performance value. Added to all

this, DLC coating provides significantly longer lifetime and durability as well as

chemical inertness under high temperature and friction.

10

Moreover, DLC coating of metallic saws for use in bone cutting results in twice the

tool’s lifetime over alternative methods; but even more importantly it resulted in low

frictional heating and higher quality of cut and bone necrosis (killing of bone tissue)

which results for the new tissue to take cut area easily and reduced healing period

according to Makino (2009).

Another vast application of DLC coatings can be found in Engines and mechanical

components. In engine applications, DLC coating of different engine components

which are exposed to high friction and wear such as pistons, piston rings and pins,

connecting rods, valves, camshaft and followers, rockers, gear and bearings have

shown significant improvements in performance gain and durability as well as fuel

efficiency. According to a study by Wei et al (1999), DLC coating of the cams and

bearings of a 500cc formula motorbike engine resulted in 8 break horsepower gain

over the uncoated engine.

Figure 10: DLC coated cam, rocker, piston, rods and bearings

Additionally, DLC coating of the interior layer for pipes with DLC films has shown to

provide excellent hardness as well as vastly reduced coefficient of friction and wear

rate as shown by the table below (Figure 11). Application of these pipes can be found

in industries such as oil and gas, tribological and corrosion performance oriented

improvements in pump barrels, downhole pipes etc. (Kobe Steel Ltd, 2010).

Figure 11: Wear rate and coefficient of friction of DLC coated and uncoated pipes

11

Testing Method SelectionA set of criteria was constructed to provide a list of various testing methods that

would help determine the feasibility of DLC coated tape, these criteria can be

summarized as follows:

How resource intensive is the testing method?

This is significant as the pool of resources for this project is limited and any cost that

exceeds this limit would leave the project incomplete. In terms of resources this

encompasses financial budget and raw materials.

How valid is the testing method?

If this isn’t taken into consideration there is a high possibility that the project will be

moot and not provide any significant insight into the feasibility of DLC coated

adhesive tape, thus this should be the first question that is asked before any method

can be considered.

How accurate is the testing method?

This is different from validity as it indicates essentially how close the values

interpreted from the results are to the actual values, this is important in its own right

as the data obtained from an accurate testing method can be transferred and applied

in various other applications as true values.

How easily can the method be performed?

This refers to the skill cap required to perform the chosen method, this can refer to

any specialist tools that may be required to perform a certain method, whether

specific facilities are needed for the performed experiment.

With these questions taken into consideration a specific set of Design Criteria can be

obtained, a Minimalistic approach has to be taken in the selection process as the

physical resources available for the project are limited, this however cannot come at

the cost of legitimate data that is valid to draw conclusions from. The data itself does

not have to be to high level of precision and accuracy, this is because to test the

feasibility of DLC tape, the coatings only have to perform relative to other DLC

coatings of different thicknesses. The project is also short term and therefore the test

has to be relatively simple to perform thus allowing ample time for data analysis and

drawing conclusive evidence of the feasibility of DLC coated adhesive tape.

12

Alternative Testing Methods

Ball-on-Flat (Heimberg et al, 2001)Heimberg et al (2001) performed reciprocating ball-on-flat friction tests, utilising a

tribometer. An investigation was carried out into the effect of time and speed on

super-low friction behaviour of DLC coatings. The experiment was designed to

achieve friction coefficients down to 0.001 at atmospheric pressure in dry nitrogen,

with the friction behaviour explained in terms of gas adsorption. The coatings were

prepared by low temperature, plasma assisted chemical vapour deposition to 1µm

thickness on sapphire and steel balls, and on steel flats. The ball was loaded against

the flat to 9.8N. Each track was initially run-in for 1000 cycles at constant sliding

speeds, in order to find an average value for the friction coefficient.

The aim of this experiment was to achieve super-low friction, and therefore carried

out to a high degree of accuracy. Friction coefficients as low as 0.007 were obtained

at high speeds, which were slightly higher than expected. This was due to the

interaction time between the surfaces. At shorter test times the average friction

coefficient decreased to 0.003. This particular method takes a relatively time-

consuming approach to calculate the friction coefficient. Due to this, a more time-

effective method to calculate the average friction coefficient was developed. The

same method of applying the DLC coating, PCVD, was also used. However in the

ball-on-flat experiment, the coating was applied onto metal, whereas we are applying

the coating to tape. A different coating thickness was also used for the ball-on-flat

experiment.

Figure 12: Ball-on-Flat

Pin-on-Disc

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Kano and Yoshida (2010) carried out pin-on-disc tests, in which ultra-low friction of

DLC coating with lubricant was investigated. Both reciprocating and rotating sliding

tests were conducted. The experiment was designed to investigate the theory that

reducing the mechanical friction in an engine would improve the fuel economy, and

the effect that this method would have on the friction between the cam and follower

of an engine. Three types of coating were applied to each surface, with and without

lubrication, in order to find the best combination for optimal friction coefficient. While

it was vital to the proposed experiment, this procedure requires extra machinery and

funding as well as copious amounts of time. The results showed that the ta-C(T)

coating, coupled with the oleic acid lubrication, provided the lowest friction coefficient.

When considering the practical applications of the DLC coated sticky tape, lubrication

can be factored out as it is irrelevant.

Figure 13. Pin-on-Disc Sliding Test

Laboratory Bench Rig (Gangopadhyay et al, 2011)The test utilised a Plint TE77 test rig. An uncoated, reciprocating polished cylinder

was loaded against a coated steel flat, with test duration of one hour, conducting

tests with and without lubrication. The aim for this experiment was to understand the

interactions of lubrication additives with DLC coating. As stated previously, the use of

lubrication is irrelevant for the adhesive tape tests. While the method of polishing to

decrease surface roughness is useful in obtaining the desired results, it is difficult

and time-consuming to polish the tape and therefore this process will not be carried

out. However, wiping the tape with disinfectant after each test run will be necessary

as it is a quick process and allows for smoother contact between surfaces. The

14

cylinder was loaded to the flat at 240N, whereas the sliding test will not require any

load, allowing for a simpler method. Results for this testing method showed that the

friction coefficient decreased with time. This contradicted the ball-on-flat method, due

to the use of lubricants. Results also showed that unlubricated tests had a lower

friction coefficient overall. A rise in oil temperature also gave higher friction

coefficients. However the surface roughness did not have much effect on the friction

coefficient, with no visible wear observed on either contact surface.

Figure 14. Plint PE77 Test Rig (Gangopadhyay et al, 2011)

Motored Valvetrain Rig for Friction Evaluations (Gangopadhyay et al, 2011)A rig was constructed in order to represent an actual engine. This method of testing

the effect of lubricants on DLC coatings is highly expensive due to the technology

applied and materials used. Aside from conducting lubrication tests, the rig was run

at various speeds in order to evaluate friction torque, resulting in lengthy tests.

Results showed that the friction torque decreased with increasing engine speed,

suggesting the system operates in a mixed lubrication regime. The polished buckets

showed substantial friction reduction at all speed, confirming the importance of

surface roughness. The unlubricated DLC coating test showed significant reduction

in friction coefficient compared to the steel-steel pairing, due to the formation of a

transfer layer. The friction coefficient was slightly higher with oil than without, and the

wear was higher with DLC coating than without, in lubrication tests.

15

Figure 15. Motored Valvetrain Rig (Gangopadhyay et al, 2011)

Twin-Disc Testing Rig (Löhr, 2006)Wear tests were carried out on different DLC coatings under lubricated and dry slip-

rolling friction in a twin-disc testing rig. The analysis of acoustic emission (AE)

provided an easy and comfortable tool for monitoring the wear life of DLC coatings.

Steel samples with a thin DLC coating were tested under both lubricated and dry slip-

rolling friction in an Amsler-type twin-disc wear tester. Two disc specimens formed

the test setup, rolling against each other with a slip of approximately 10%. A pressure

of up to 2.3GPa was observed in the centre of the contact area. A steel bearing

served as the substrate of the DLC coating as well as the material of the counter

body. Only the cylindrical specimen was coated with an interlayer and a DLC-coating

using AE.

The experimental setup is simpler than other testing methods, as it uses two discs,

one of which is coated. The main difference is that it incorporates a sensor, which

measures the acoustic emissions. Acoustic emissions such as this are related to the

irreversible changes that a material undergoes in its internal structure.

16

Figure 16: Twin Disc Wear Tester (Löhr, 2006)

Depending on the intended application, testing methods for DLC coating will differ. A

test was carried out to investigate the effect that DLC coating has on the frictional

properties of orthodontic wires. Two types of wire (nickel-titanium and stainless steel)

were coated with DLC. Three types of brackets, a conventional stainless steel

bracket and two self-ligating brackets, were used for measuring static friction. DLC

layers were observed by three-dimensional scanning electron microscopy (3D-SEM),

and the surface roughness was measured. Frictional forces and surface roughness

were compared by the Kruskal-Wallis and Mann Whitney U-tests.

This method is carried out on a relatively small scale due to the intended application.

Two materials were used for coating. Our experiment involved the use of steel and

MDF as the counter surface for the DLC coating. (Muguruma et al, 2011)

MethodologyAs mentioned prior the testing method is required to meet a few specifications before

it can be considered as the chosen method. A factor to take into consideration is that

the data analyzed is relative, this means that systematic errors that maintain a

constant effect on all results are irrelevant, as this will not affect the result’s worth as

they are still valid for the purpose of this investigation.

The chosen testing method involves a metal block of dimensions

79mmx50mmx20mm and weight 623 grams placed on a ramp that can be adjusted

17

in slope angle at a range of intervals until points of both static and dynamic friction

can be observed.

The metal block will have tape attached to its long faces with different thicknesses of

DLC coating, all of which will be tested and compared to one another. The ramp had

to be built using two separate panels of MDF, both of dimensions

800mmx27mmx12mm attached together using a flexible metal hinge, the hinge

allowed for the ramp itself to be adjustable. For the first set of testing, a separate

wooden block was used as a slider to achieve fixed variation in slope angle. This

method however only allowed for a very small range of different slope angles and

also lacked the level of precision that was necessary when adjusting the slope angle,

also it required manual movement increasing the effect of human error on the results

and thus making the results less reliable.

Thus a new method of adjusting the slope angle would be required, instead of using

a wooden block as a manual sliding mechanism, a scissor lift of appropriate

dimensions was used instead, this piece of equipment provided a much larger range

of heights while providing precise height adjustment thereby allowing for more

accurate observations.

18

Figure 18: The different thicknesses of DLC coated tape with no coating on the left 0.8 microns in the middle with 1.2 microns on the right

Figure 20: Wooden block used as slider

Figure 17: Metal block

Figure 19: Constructed Incline Plane

The MDF surface would also need to be taken into consideration as it was providing

inconsistent results as well as the observation points exceeding the large range of

the scissor lift, this meant that a surface with a lower coefficient of friction was

necessary so that the observation points occur at smaller angles that the scissor lift

can reach, to achieve this a metal sheet was attached to the MDF surface and was

tested following the same parameters as the MDF surface.

With the metal block placed at a fixed point on the ramp, the ramp was moved

steadily through a range of increased slope angles whilst being stopped at regular

intervals. At these intervals energy was applied to the system in the form of a simple

tap to the testing rig at a fixed location, after the tap the metal block would be

observed to see if it had reached a certain point, the points that require observing are

when static friction occurs and when dynamic friction occurs.

This method of testing, as the analysis is relative, requires consistency in the defined

points (Datum points) in order to yield valid results since the results are only

compared to each other. With this taken into account the point of static friction has

been quantified for this experiment as the point when the metal block moves a

considerable distance and then stops, a considerable distance in this case is

approximately half the length of the block. The point of dynamic friction is much

19

Figure 21: Scissor lift as used in experiment

Figure 22: Metal hinge used for the ramp

Figure 23: Sheet Metal used as surface

Figure 25: Diagram representing the use of similar triangles to calculate the angle

easier to quantify and observe, as it is the point that the metal block begins moving

freely without stopping, in essence friction has been overcome.

When it comes to measuring the actual results, the desired information is the incline

plane angle with the horizontal, however measuring this angle manually inputs a lot

of human error, to avoid this basic trigonometry is used to calculate the angle

instead, to further reduce human error the elevated height is only measured from a

predetermined datum point that is constant throughout the experiment. The reason

that measuring the length is unnecessary is because the triangles are similar,

therefore the angle will remain constant, this helps reduce human error by reducing

the number of manual measurements that need to be taken thus making it more

effective in providing valid data.

A Metal Block

B Scissor Lift

20

G DC

A

F

E

B

Figure 24: Datum point for height measurements

Figure 26: Experimental rig set up

C Wooden Ramp

D Metal Sheet

E Dial

F Metal Hinge

G Datum Point

Calculations and Results

CalculationsThe aim of this experiment is to obtain the friction coefficient values for the different

surface types. This was achieved by using calculations for an inclined plane, such as

the weight components. Figure 27 shows how the experiment was modelled

mathematically for the analysis. Table 3 shows the definition of the notation from the

model.

Figure 27: Mathematical

Notation Definition (unit)

m Mass (kg)

mg Weight (N)

mgcosθ = N Normal/Reaction forces (N)

Mgsinθ Driving force (N)

f Frictional force

θ Plane angle (degrees)

In the

experiment, the values that were obtained are the ‘adjacent’ and ‘opposite’ distances

of the right angle triangle. As mentioned in the methodology the adjacent distant was

21

Table 2: Experimental rig components

Table 3: Notations and definitions of mathematical model

kept constant at 400mm in order to reduce the factor of error in the obtained data.

Table 4 shows the values obtained from the experiment for an MDF surface, and

table 5 shows the values obtained from a steel plate surface.

Table 4: Experimental values of MDF

Using the trigonometric function ‘tan’, where tan (θ )= oppositeadjacent , the plane angle can

be calculated, as shown in table 3 to 2 . The excel formula used is:

=DEGREES(ATAN(Opposite/Adjacent)). Excel does its trigonometric calculations in

radians, whereas the angles was preferred in degrees.

22

Table 5: Experimental values of Steel Plate

MDF

Static Dynamic

A

(mm)

O

(mm)

A

(mm)

O

(mm)

metal 400 77 400 140

400 73 400 127

400 71 400 126

400 72 400 140

400 70 400 113

thin 400 84 400 91.5

400 85.5 400 90

400 88.5 400 89.5

400 88 400 89

400 88.5 400 90

thick 400 80.5 400 86

400 81 400 83

400 79 400 85

400 80 400 83

400 78 400 82

Steel Plate

Static Dynamic

A

(mm)

O

(mm)

A

(mm)

O

(mm)

tape 400 90 400 101

400 92 400 101

400 95 400 100

400 90 400 107

400 91 400 103

thin 400 86 400 96

400 84 400 96

400 85 400 95

400 85 400 95

400 86 400 96

thick 400 80 400 90

400 79 400 92

400 77 400 93

400 79 400 92

400 80 400 93

The next parameter that needs to be calculated is the driving force. The driving force

is the component of the metal blocks weight that is dragging the block down the

slope. The mass of the block is a constant value that is weighed to be 0.623kg. Using

this mass value, and the value of constant gravitational acceleration, the weight of

the steel block can be calculated using a simplified Newton’s second LawF=ma

where F is the force, m is the mass and a is the acceleration . This makes the weight

of the steel block 6.11163 N. This force is pulling the block downwards, perpendicular

to the floor, not the inclined slope as this is an effect of gravity which pulls objects

towards the earths centre. The driving force is the force vector that is parallel to the

inclined slope. This is calculated via simple trigonometry by multiplying the weight of

the block by the sine of the plane angle:mgsin (θ). This parameter is very important

when comparing static and dynamic friction. The driving force for a static friction test

theoretically is also equal to the frictional resistance force applied by the two

surfaces, to stop the block from slipping down the slope. As the angle is increased

23

Table 6: Plane angle for all tests

MDF Metal Plate

static dynamic static dynamic

Ө

(degrees)

Ө

(degrees)

Ө

(degrees)

Ө

(degrees)

Metal/Tape 10.90 19.29 12.68 14.17

10.34 17.61 12.95 14.17

10.07 17.48 13.36 14.04

10.20 19.29 12.68 14.98

9.93 15.77 12.82 14.44

thin 11.86 12.88 12.13 13.50

12.07 12.68 11.86 13.50

12.48 12.61 12.00 13.36

12.41 12.54 12.00 13.36

12.48 12.68 12.13 13.50

thick 11.38 12.13 11.31 12.68

11.45 11.72 11.17 12.95

11.17 12.00 10.90 13.09

11.31 11.72 11.17 12.95

11.03 11.59 11.31 13.09

gradually, so is the driving force component. The angle is increased until it is

observed that the block reached the static point of friction as defined in the

methodology section, which for the purpose of this testing is more convenient. This

demonstrates that the driving force has now equalled or ever so slightly surpassed

the frictional resistance value. This value is very important when working out the

friction coefficient µ. For the dynamic tests, the static frictional resistance is used

because theoretically, this value is constant for the same two frictional surfaces. The

Driving force is shown in table 5, to 2d.p.

The other component that the weight of the block produces is the force that the block

presses perpendicular to the inclined plane. This force keeps the block planted on to

the inclined surface. According to Newton’s third law of motion, the inclined plane is

applying an equal force back onto the block. This force is known as the reaction

force. This can be calculated by using simple trigonometry again and with the same

formula as the driving force, except a cosine function is used:mgcos(θ). This is useful

as it has a direct link to the calculation of the coefficient of friction. This is also shown

in table 7.

MDF Metal Plate

Driving

Force

Reaction

Force

Driving

Force

Reaction

Force

Metal/Tape 1.16 5.96 1.34 5.93

1.10 5.96 1.37 5.93

1.07 5.95 1.41 5.93

1.08 5.96 1.34 5.90

1.05 5.96 1.36 5.92

thin 1.26 5.98 1.28 5.94

1.28 5.98 1.26 5.94

1.32 5.98 1.27 5.95

1.31 5.98 1.27 5.95

1.32 5.98 1.28 5.94

thick 1.21 5.99 1.20 5.96

1.21 6.00 1.18 5.96

1.18 6.00 1.16 5.95

1.20 6.00 1.18 5.96

1.17 5.99 1.20 5.95

24Table 7: Weight components

The friction coefficient is calculated using the formula:FR=μ× R, where FR is the

frictional resistance, µ is the coefficient of friction, and R is the reaction force exerted

by the inclined plane. It is this parameter that we expect to minimize using the DLC

coating. This means that less force is required to move the object down the inclined

slope. As mentioned previously, the frictional resistance for dynamic tests will be the

same as the static tests, as that is the maximum friction experienced. Table 8 shows

these values, and table 9 shows the average of the 5 repetitions for each test.

Table 8: Friction coefficients for all tests

The Metal Block

25

Table 9: Averages of all tests

MDF Metal Plate

Static Dynamic Static Dynamic

µ µ µ µ

metal 0.1925 0.200273 0.225 0.226402

0.1825 0.188367 0.23 0.231183

0.1775 0.183234

0.237

5 0.238184

0.18 0.18769 0.225 0.22723

0.175 0.179127

0.227

5 0.229068

thin 0.21 0.210826 0.215 0.216166

0.21375 0.214254 0.21 0.211353

0.22125 0.221367

0.212

5 0.213641

0.22 0.220116

0.212

5 0.213641

0.22125 0.221426 0.215 0.216166

thick 0.20125 0.201803 0.20 0.201019

0.2025 0.202699

0.197

5 0.198816

0.1975 0.198084

0.192

5 0.194071

0.2 0.200294

0.197

5 0.198816

0.195 0.195375 0.2 0.201347

MDF Metal plate

static dynamic static dynamic

metal 0.1815 0.187738 - -

tape - - 0.229 0.230413

thin 0.21725 0.217598 0.213 0.214193

thick 0.19925 0.199651 0.1975 0.198814

Results :

1 2 3 4 50.15

0.16

0.17

0.18

0.19

0.2

0.21

0.22

0.23

Data trend of static tests with MDF

metalthinthick

test number

coef

fici

ent

of fr

icti

on

Figure 28: Data for each repetition of the experiment for static friction using MDF

26

L

D

H

D = 20 mmL = 78 mmH = 51 mmArea = 0.00156 m2

Mass/Weight = 0.623kg/6.11163NThe Area is defined as the surface area for one of the surfaces that will be making contact with the inclined plane for the purpose of testing, therefore this means that these faces will be the ones that are DLC coated as well.

1 2 3 4 50.15

0.16

0.17

0.18

0.19

0.2

0.21

0.22

0.23

Data trend of Dynamic tests with MDF

metalthinthick

test number

coef

fici

ent

of fr

icti

on

Figure 29: Data for each repetition of the experiment for dynamic friction using MDF

metal thin thick0.15

0.16

0.17

0.18

0.19

0.2

0.21

0.22

0.23

Data trend of static tests with metal, thin and thick, on MDF

test1test2test3test4test5average

Testing element

coef

fici

ent

of fr

icti

on

Figure 30: Comparison of data spread for each testing element and the averages, for

static tests on MDF

27


0.16

0.17

0.18

0.19

0.2

0.21

0.22

0.23

Data trend of Dynamic tests with metal, thin and thick, on MDF


Testing Element

coef

fici

ent

of fr

icti

on


dynamic tests on MDF

1 2 3 4 50.15

0.16

0.17

0.18

0.19

0.2

0.21

0.22

0.23

0.24

0.25

Data trend of static tests with Metal plate

Tapethinthick

test number

coef

fici

ent

of fr

icti

on

Figure 32: Data for each repetition of the experiment for static friction using Metal

plate

28

1 2 3 4 50.15

0.16

0.17

0.18

0.19

0.2

0.21

0.22

0.23

0.24

0.25

Data trend of Dynamic tests with Metal plate

tapethinthick

test number

coef

fici

ent

of fr

icti

on

Figure 33: Data for each repetition of the experiment for dynamic friction using Metal

plate

tape thin thick0.150.160.170.180.19

0.20.210.220.230.240.25

Data trend of static tests with metal, thin and thick, on Metal plate


Testing element

coef

fici

ent

of fr

icti

on


static tests on Metal plate

29

tape thin thick0.15

0.16

0.17

0.18

0.19

0.2

0.21

0.22

0.23

0.24

0.25

Data trend of dynamic tests with metal, thin and thick, on Metal plate


Testing element

coef

fici

ent

of fr

icti

on


dynamic tests on Metal plate


0.17

0.18

0.19

0.2

0.21

0.22

0.23

Average µ for MDF

staticdynamic

Testing element

Coef

fici

ent

of F

rict

ion

Figure 36: Comparison of averages of static and dynamic tests, for all testing

elements on MDF

30

tape thin thick0.18

0.19

0.2

0.21

0.22

0.23

0.24

Average µ for Metal Plate

staticdynamic

Testing element

Coef

fici

ent

of F

rict

ion

Figure 37: Comparison of averages of static and dynamic tests, for all testing

elements on Metal plate

MDF Metal plate0.21

0.211

0.212

0.213

0.214

0.215

0.216

0.217

0.218

MDF vs metal plate Thin comparison

thin StaticThin Dynamic

Testing Surface

Coef

fici

ent

of F

rict

ion

Figure 38: Comparison between static and dynamic values for both testing surfaces,

for the thin testing element

31

MDF Metal plate0.196

0.1965

0.197

0.1975

0.198

0.1985

0.199

0.1995

0.2

MDF vs metal plate Thick comparison

thin StaticThin Dynamic

Testing Surface

Coef

fici

ent

of F

rict

ion

Figure 39: Comparison between static and dynamic values for both testing surfaces,

for the thick testing element

1 2 3 4 50.204

0.206

0.208

0.21

0.212

0.214

0.216

0.218

0.22

0.222

0.224

MDF vs Metal in thin static and dynamic

static MDFdynamic MDFstatic Metaldynamic Metal

Test Number

Coef

fici

ent

of F

rict

ion

Figure 40: Comparison of all test values for thin element

32

1 2 3 4 50.186

0.188

0.19

0.192

0.194

0.196

0.198

0.2

0.202

0.204

MDF vs Metal in thick static and dynamic

static MDFdynamic MDFstatic Metaldynamic Metal

Test Number

Coef

fici

ent

of F

rict

ion

Figure 41: Comparison of all test values for thick element

Discussion

MDFFigures 28 and 29 display a comparison of the experiments. For different testing

elements, it is noticeable that for both the static and the dynamic tests the metal

surface has the lowest coefficient of friction throughout all 5 repetitions. This deviates

from our expectations, as we expect the metal to demonstrate a higher frictional

coefficient than the DLC films. These anomalous results could be attributed to the

actual surface of the metal block that made direct contact with the inclined plane.

This MDF surface, after repeat testing, may have formed slip lines that are parallel

with the motion of the block, hence increasing the size of the plane angle that the

points of static/dynamic friction occur. This is because the surface finish is not taken

into consideration when calculating the value for the coefficient of friction, therefore

the minimal contact on the MDF board caused by the slip lines reduce the friction.

This factor becomes even more valid when taking into account that the DLC coated

tape overlapped the metal surface. This means that for the DLC friction tests, the slip

lines were not a present factor as the surface dimensions were different and

therefore could not be utilized in a similar manner as when the bare metal surface

was used.

33

The MDF board is made from bonding multiple wood fibres together using an

adhesive, thus the testing surface was not ideal since it is not uniform throughout the

wooden surface. Therefore each test had to start at the exact same position on the

MDF board; otherwise it would not have been an accurate test. However this method

of controlling variables produces the issue of repetitive wear on the relevant surfaces.

Subsequently after each test, the position used as the initial starting position would

receive some wear, thus making that particular location smoother than before

causing a systematic error that will have a significant effect on further testing.

Another by-product of repetitive use is physical erosion of the DLC coating, which

makes the film surface rougher and thus increases friction. We see this in action for

the thin element especially; which demonstrated surface damage after the first few

tests. This does plateau after test 3, suggesting that the wear and tear on the

elements was only done to the weak bonded regions as the material that had not

been worn away was intact, this however could be a factor of the irregularities on

both the finish of the metal block and the surface of the inclined plane.

The results displayed by figures 28 and 29, show that all three elements had very

similar friction coefficients after the first test, as none of the previously mentioned

biases were in play, therefore that set of results are the most reliable. From here, the

difference between the coatings increase as the aforementioned biases begin to take

effect; increasing systematically after every test. Despite this, the results followed the

expected trend, in that the thicker DLC element experiences less friction than the thin

equivalent. This is the natural assumption as a thicker DLC coating means that the

properties of the DLC substrate are more prominent, due to the fact that they are less

influenced by the metal surface underneath.

Figures 30 and 31 show how the data is spread for the respective testing elements,

and the average trend for each element. These graphs show how widely distributed

the data is for the static and dynamic tests. We can see that the results for the static

and dynamic friction have very little difference in terms of range between various

results, suggesting that both of the respective friction coefficients are similar. Also the

similarities between the results make it seem as if they are consistent repetitions,

except for one point in the metal element testing set that occurs at a significant

distance above its relative test values, seeming to deviate away from the rest. This

anomalous result could very well be deduced from human error as the plain metal

surface was the first set of tests performed and therefore the testing procedure was

not well versed at this point. Figures 28 and 29 share the same evidence in terms of

34

the comparison between the dynamic and static values. Although it does look like an

outlier, it there is a valid explanation for its presence. We also see the previously

mentioned anomaly of the metal element producing a much lower friction coefficient

in comparison to the other two elements

Metal SheetThe data obtained from the tests which implemented the metal sheet (graphed and

shown in figures 32-35) are much more promising than the MDF results. Figures 32

and 33 show the data trends for the three testing elements; uncoated tape, thin DLC

coating, and thick DLC coating. In these tests, plain adhesive tape was used as a

testing element instead of the metal surfacing.

The first reason for applying the tape is that it has a much more uniform surface in

comparison to the metal surface. This means that there are less parameters that

could potentially affect the results. Another reason for using the tape is because the

metal sides used for testing were already used for the DLC coating strips. The tape

was the same tape that was used as the adhesive for the DLC coatings, therefore the

comparison was more consistent. If the metal surface was required to be used, the

DLC coatings would have to be removed, and the surface would have to be polished

to remove any adhesive stuck onto the metal. This process could greatly deter the

results of the experiment.

The figures 32 and 33 show exactly what would be expected from the experiments

for each test. The figures show that the highest resistance to motion is the plain tape

surface, next is the thin coating, and finally the thick coating. This observation is

consistent with every repetition of the test, as well as the static and dynamic tests.

The variation from the average test values is not significant, confirming the reliability

of the results. There is a slight abnormality in tape results for the third test, where the

friction coefficient is noticeably higher than the rest of the results. This is in fact

expected, because during the test we realised that the tape accumulated some

contamination, which needed to be removed before any other tests continued. After

removing this small abnormality the results show a much more consistent trend. By

using the metal sheet, we removed the effect of compression on the fibres on the

MDF. The effects of this change are shown in the figures, as the data trend for all

friction tests does not decrease, staying more parallel to the horizontal axis.

35

Figures 34 and 35 show how the data is spread for each testing element, as well as

how each element compares with the other. Both graphs show practically identical

graphs, meaning that the differences between the static and dynamic friction

coefficients are miniscule. For each testing element, we see that there is extremely

small deviation from each result, thus demonstrating the reliability of these

experiments. The trends of averages for each element are very satisfying. It shows

that as the DLC coating gets thicker, the friction of the surface reduces too. This is

represented with a linear looking line on the graph. This is exactly what we expect

from these tests and shows that choosing the tape did in fact deliver more concise

results.

Comparison Figure 36 and 37 show the comparison of the averages of static and dynamic

coefficients of friction, for each testing element and testing surface. Straight away, we

see that there is a concern with the metal results on the MDF, and this issue has

been discussed above. The metal plate graph shows a more comforting negative

correlation as the DLC coating increases. A notable observation would be that for all

test averages, the static friction is always lower than the dynamic coefficient of

friction. This is a desirable result, duly because of the definitions of static and

dynamic frictions the static friction is always lower than dynamic friction. For the MDF

metal test, the dynamic is substantially higher than the static. This could be because

of non-uniformity of both the MDF and the metal surface. This means that a greater

driving force is required to overcome many contacts of the grooves on both surfaces,

that keep 'hooking' onto each other, stopping the steady flow to characterise the

result as dynamic.

Figures 38 and 39 display a comparison of the different testing surfaces with both

static and dynamic, with respect to the thin and thick DLC coatings. It is seen

immediately that the MDF has a much higher coefficient of friction compared to metal

plate. This is mostly because of the high friction surface of the MDF where the

surface is not uniform and it is comprised of fibers instead of a smooth one piece

surface. The other noticeable fact is that the difference of static and dynamic for both

coatings, is much larger with the metal plate than the MDF wood. A reason for this

could be because the metal surface or the coating was not cleaned properly, thus

leaving contaminants, making it much harder for the block to slide down the inclined

plane, increasing the result for dynamic tests. Even with this difference, when

36

comparing numerically, the difference is practically non effective, as the difference is

in the thousandths.

Figures 40 and 41 show how the coefficient of friction varies with the static and

dynamic tests for the two testing surfaces, with respect to the DLC coating thickness.

It is show in both graphs that for most of the tests, the MDF has a higher coefficient

of friction than the metal plate, but there are two tests (test 1 for thin, and test 5 for

thick) where the metal plate has a higher static and dynamic coefficient of frictions.

These could be abnormalities, although the differences are excusable, as they would

not have any practical difference to the experiments. Figure 14 shows that as the

tests progress, the coefficient of friction increases for the static and dynamic MDF.

The reason has been mentioned previously, where the coating on the adhesive

would get scratched after each test, thus increasing its resistance to surface slip. We

see that every other trend on both graphs has some oscillations but numerically, they

are all stable towards an average figure that doesn't deviate away from all the

results. This shows the consistency and reliability of the results obtained from the

experiment.

Other conditions could have an impact on the results of the experiments, such as the

humidity and the temperature of the room. The humidity would affect the MDF, and

the resistance of micro condensation on the steel and the testing elements. The

temperature would mostly have an effect on the metal block, as it would increase the

surface area, thus spreading or concentrating the force and resistance over the area.

This could have an effect on the pressure exerted by the weight of the block, as it is

inversely proportional to area.

37

Conclusions and the future of DLC Coating

The main objective of this investigation was to discover how feasible DLC coated

adhesive tape is as a low friction material. The idea behind it being that the DLC tape

can be conveniently placed on various different surfaces and help enhance some

sort of feature using its valuable properties, an example being the inside of a chest of

drawers to help the drawers to be extracted smoothly.

With this in mind the testing showed, although with the anomaly of the metal block

itself, that the DLC coating possessed superior properties in terms of being a low

friction material. This can be concluded from the relatively much lower coefficients of

friction obtained from the DLC coated materials, this claim can be supported further

by the thicker DLC coating showing more promise than the thinner coating, therefore

a positive relationship exists between the thickness of the DLC coating and the

coefficient of friction.

However there is still a lot left desired from how the testing method that was

performed. A key benefit of this method was its simplicity, however this criteria was

so critical due to the time constraint that it came at the cost of a truly accurate and

precise testing method. A key drain in the precision was the means of applying

energy to the system, this force was generated by a human element and

subsequently is prone to human error. In hindsight, this step of the experiment could

have been automated using a small electric fan of some sort that applies a

continuous subtle force, this would have reduced the time significantly between

intervals and allowed for more accurate results that in turn would provide clearer

evidence. Another source of error was the manual increase of the plane angle. This

could have been automated as well, but more importantly the plane angle was not

sensitive enough to the rotation of the dial, and as a result significantly reduced the

precision of the recorded data.

Other researchers previously performed similar testing that shared the same premise

albeit with one key difference. This difference was that not only the DLC coating

applied was applied, but various different lubricants were tested on top of the coating

as well, this was in an attempt to find the best combination that provides the most

useful properties. The reason this statement is relevant is because these lubricants

could in effect enhance the feasibility of DLC coated tape, thus a more in depth study

that involved unlubricated and lubricated DLC tape could enhance the conclusions

drawn from this experiment.

38

Not only was the precision of the test lacking but the test ranged between too few

materials and therefore a further in depth study will be required to truly assess the

feasibility of DLC coated tape. A material that would help increase the depth of the

study is Teflon, a material commonly used for its low friction properties which seems

an obvious choice for further comparative testing. This would provide an interesting

perspective on the future of DLC coating applications, as proof of DLC coatings

properties being superior then popularly used materials used in industry speaks

volumes about other possible uses of DLC coating. The current applications of DLC

coatings have been discussed in previous sections, these applications being

prevalent in many areas especially the medical and automotive industry.

However all these uses are involved heavily in the industrial sector where it has been

recognised as highly valuable to informed minds, and an area it will continue to

expand its presence. This insinuates that there is still a lot of possibilities for DLC to

grow, one of these possibilities being in the tertiary sector, this is especially so for the

DLC coated tape, as the ability to conveniently reduce the friction of a surface

implicates many possible uses that have yet to be delved into, thus making it a very

interesting prospect.

As promising as the future of DLC is, there are still some issues that need to be

addressed before it can be fully utilized. One of these issues is the possible

thicknesses of the coatings, currently these are approximated at 2 micrometres.

Naturally this is a big obstacle as the properties of the DLC coated tape are directly

related to the thickness of the coating, at this point in time there is research being put

into reducing these internal stresses, thus implicating thicker coatings in the future.

Overall the future of DLC coated tape seems very positive, there is a lot of room left

for DLC coatings to develop yet it is already being heavily utilized in industry, if this

success translates to the tertiary sector then the tape will become even more

relevant as a temporary coating of DLC from a worn away DLC film or allowing the

coating of a less conventional object.

39

Project Management - Critical Assessment

Task NameStart Date End Date

Research 12/01/15 30/01/15Future Applications 12/01/15 30/01/15History of DLC Coating 12/01/15 16/01/15Alternative Testing Methods 14/01/15 21/01/15Physical Attributes 19/01/15 23/01/15Chemical Compositions 19/01/15 21/01/15Overall Friction Research 28/01/15 30/01/15

Testing 02/02/15 20/02/15Experimental Setup 02/02/15 03/02/15MDF Testing 03/02/15 06/02/15Metal Plate Testing 09/02/15 13/02/15Further Tests to exclude Anomalies 16/02/15 18/02/15Data Processing 19/02/15 20/02/15

Report Writing 23/02/15 06/03/15Introduction 23/02/15 25/02/15Literature Review 23/02/15 27/02/15Methodology 23/02/15 25/02/15Results 23/02/15 24/02/15Discussion and Conclusion 02/03/15 06/03/15Project Management 02/03/15 03/03/15

Table 10: Project time management

Overall the project ran smoothly, there was a week delay in acquiring a lab to

perform our experiment. However this was counteracted by the extra background

research performed during this week, which subsequently reduced the time taken to

write up the literature review. The tasks could have been delegated better, a method

of this would be to give members more tasks, but in smaller sections so that the team

could perform the write up in a more synchronized approach. With that said the lag

that occurred between tasks due to this was almost negligible, this is because the

plan was designed to leave excess time for the final formatting of the report as a

countermeasure for any possible uncertainties.

If this project was repeated, even though the task was set over a brief period,

perhaps an extra week could have been utilised to obtain the means to perform a

well-controlled experiment. Such components include the humidity and temperature,

which had a definite impact on the obtained results. Following this extra time would

be needed to make the recommendations mentioned in the conclusion section.

40

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