Laboratory of Tribology

Holon Institute of Technology

Prof. Lev Rapoportrapoport@hit.ac.il

Why Fullerenes ?

L. Rapoport, et al.

“Hollow nanoparticles of WS2 as potential solid‐state lubricants”

Nature, 387 (1997) 791‐793

The Absent of Dangling Bonds

The IF Nanoparticles in an Interface

C. Drummond et al., Micro‐tribology and friction‐induced material transfer in WS2nanoparticle additives, Advanced Functional Materials, 11, (2000)348

L. Rapoport et al., Slow release of fullerene‐like WS2 nanoparticles from Fe‐Ni‐graphite matrix, Nanoletters, 1, 2001, 137

IF‐WS2 Nanoparticles under Compression

Friction and Wear of IF under Severe Contact Conditions

Impregnation of Solid Lubricant into Porous Matrix

IF

Friction and Wear  of Grease with IF Nanoparticles

Grease + IF-WS2

0.005

0.007

0.009

0.011

0.013

0.015

0.017

0.019

0.021

0 500 1000 1500 2000 2500 3000 3500

Load, N

Fric

tion

coe

ffic

ient

IF

2HBase Grease

Fig 7

Advanced Materials, 15(7‐8), 2003 (1‐5) 

Wear, 255, 2003 (794‐800)

The Applications

Based on the Discovery of Prof. Tenne’s Team and the investigations of friction and wear in HIT, Nanomaterials, 

Ltd. company was created in 2002.

LST of Steel Surfaces

Burnished MoS2 Films

Burnished film on steel substrate

Burnished MoS2 film on CdZnSe sub-layer

Wear Life of Burnished Films

0

0.5

1

1.5

2

2.5

0 10 20 30 40 50 60 70

Time, min

Fric

tion

forc

e, N

1 2

(1) – MoS2 film; (2) MoS2 film on CdZnSe sub-layer

Etching of the surfaces

The surface of steel after etching The surface of steel after etching and burnishing with MoS2

powder

The Effect of roughness on Longevity of Burnished Films

Steel disk

0

0.05

0.1

0.15

0.2

0.25

0 5 10 15

Time life, min

Coe

ffic

ient

of f

rict

ion

Rz=5 Rz=1 Rz=9

The Device for Burnishing

Study of Stick‐Slip Phenomenon

Glass flat samples were moved with the reciprocal speed of 20 μm/s and minimal contact pressure of 0.5 MPa. 

The load was changed from 1.5 N to 5 N The length of the friction track was 600 μm. Three types of silicone fluid were used: DiPhenylSiloxane‐DiMetihylSiloxane (DPDMS) – 100 cSt; PolyOctylMethilSiloxane (POMS) – 450 cSt, PolyDiMethylSiloxane (PDMS) – 5000 cSt.

Glasses

The effect of testing time on friction force (F) was studied.

Stop‐start experiments allowed us to estimate the relaxation

time after the static friction overshoot. 

The effect of number of the cycles on the friction force for  the silicone oils

0

5

10

15

20

25

30

0 50 100 150 200

Number of cycles

Fric

tion

forc

e, g

5000 cSt

450 cSt

100 cSt

The time to steady friction state depended on the viscosity of the silicone fluid. The higher the viscosity of the liquid, the more the time for obtaining the steady friction state is needed. 

However, we have not revealed a roughly inverse relationship between the forces of friction and the bulk viscosity of the silicone liquids. 

It is expected that methyl groups will lead to large values of the 

for thin layers effective viscosityof silicone liquids. A tendency to maximal interlocking is observed for DPDMS liquid (100 cSt).

We did not reveal the damage of contact surfaces. An increasing the value of the friction force is associated with a thinning of the liquid silicone films.

Medical applications of self‐lubricating coatings with fullerene‐like (IF) WS2 nanoparticles

NiTi root canal files by self-lubricating coatings

Effect of Load on Scratch Tracks

Hardness Analysis

Study of Damage of Friction Surfaces

Study of the Mechanisms of Friction and Wear

Last Publications (2008‐2010)L. Rapoport, A Moshkovich, V. Perfilyev, I. Lapsker, G. Halperin, Y. Itovich, I. Etsion

Surface and Coatings Technology, 202, 2008 (3332-3340)B. Späth, F. Kopnov, H. Cohen, A. Zak, A. Moshkovich, L. Rapoport, W. Jägermann R. Tenne

Physica Status Solidi (b), 245(9), 2008 (1779-1784)L. Rapoport, A. Moshkovich, V. Perfilyev, A. Gedanken, Yu. Koltypin, E. Sominski,

G. Halperin, I. EtsionWear life and adhesion of solid lubricant films on laser-texture steel surfaces"Wear" – An Int'l. J. on the Science and Technology of Friction, Lubrication and Wear Special Issue: 17th Int'l. Conf. on Wear of Materials

Las Vegas, USA, 19-23 April 2009, 267, 2009 (1203-1207)69. L. Rapoport

Steady friction state and contact models of asperity interaction"Wear" – An Int'l. J. on the Science and Technology of Friction, Lubrication and Wear Special Issue: 17th Int'l. Conf. on Wear of Materials

Las Vegas, USA, 19-23 April 2009, 267, 2009 (1305-1310)

C. Refereed articles, contd.L. Rapoport, A Moshkovich, V. Perfilyev, I. Lapsker, G. Halperin, Y. Itovich, I. EA. Moshkovich, V. Perfilyev, I. Lapsker, L. Rapoport

Stribeck curve under friction of copper samples in the steady friction stateTribology Letters, 37(3), 2010 (645-653)

71. C. Shahar, D. Zbaida, L. Rapoport, H. Cohen, T. Bendikov, J. Tannous, F. Dassenoy, R. TenneSurface functionalization of WS2 fullerene-like nanoparticlesLangmuir, 26(6), 2009 (4409-4414)

72. V. Perfilyev, A. Moshkovich, I. Lapsker, L. RapoportFriction and wear of copper samples in the steady friction stateTribology International, 43, 2010 (1449-1456)

73. A. Moshkovich, V. Perfilyev, T. Bendikov, I. Lapsker, H. Cohen, L. RapoportStructural evolution in copper layers during sliding under different lubricant conditionsActa Materialia, 58, 2010 (4685-4692)

74. N. Parkansy, I.I. Beilis, D. Gindin, B. Alterkop, R.L. Boxman, A. Moshkovich, V P fil L R t Y R b

Holon Institute of Technology

Laboratory of Tribology