Corrossion Cavd Ppt

8/2/2019 Corrossion Cavd Ppt

1/30


2/30

According to the Federal Highway

Administration Corrosion costs U.S.Businesses an estimated $276 Billion

each year, or up to 6% of the nations

GDP.

The Cost Of Corrosion


3/30

What is the root cause of this problem ?

What is the Science Behind Corrosion ?

What Strategies and technology can beImplemented to Control Corrosion ?

Three important Questions ?


4/30

Without Corrosion protection will it

hold in a crash or fail ?


5/30


6/30

Major Drive Components being

destroyed by Corrosion will cost you

money sooner than later.


7/30

Moisture, severe temperatures, road debris ,sand,gravel and de-icing materials can sandblast vehicleunderbodies.

Once the paint coatings are chipped, even slightly,those areas are left exposed to the corrosiveenvironment.

De-icing compounds- Sodium Chloride, MagnesiumChloride and Calcium Chloride.

The Root Cause


8/30

Rear FramesGussets

Rear Under ride guards

Threshold PlatesFront Aprons

Upper Couplers

Landing Gear Brackets and Braces

Front Under Structure

Suspension and Axle Assy.

Main Frame Assy.

Areas effected by Ice Melting Chemicals &Rock Impingement


9/30

The chemical make up of Rust


10/30

Fe(s) -> + Fe2+(aq) + 2e-

The electrons can move through the metallic iron to the outside of the

droplet whereO2(g) + 2H2O(l) + 4e

- -> 4OH-(aq)

Within the droplet, the hydroxide ions can move inward to react withthe iron(II) ions moving from the oxidation region. Iron(II) hydroxideis precipitated.

Fe2+(aq) + 2OH-(aq) -> Fe(OH)2(s)

Rust is then quickly produced by the oxidation of the precipitate

4Fe(OH)2(s) + O2(g) -> 2Fe2O3 H2O(s) + 2H2O(l)

The rusting of unprotected iron in the presence of air and water is theninevitable because it is driven by an electrochemical process.However, other electrochemical processes can offer someprotection against corrosion. For magnesium rods can be used toprotect underground steel pipes by a process called cathodic

protection.


11/30

The presence of Salt greatly enhances the rusting ofmetals. This due to the fact that the dissolved saltincreases the conductivity of the aqueous solution

formed at the surface of the metal and enhances therate of electrochemical corrosion

The Science


12/30

For more than 50 years ,sodium chloride (Rock Salt)has been used for De-Icing roadways.

Magnesium Chloride and Calcium Chloride havebecome popular options due to ease and speed ofapplication, as well as being effective at low

temperatures.

The Science


13/30

CaCI2 and MgCI2 are especially destructive becausethey cling to the underbody of a vehicle andcrystallize as they slowly dry out.

These crystals are hydrophilic.

They absorb moisture keeping them in a semi-

solution state for extended periods of time, whichmultiplies their corrosiveness.

The Science


14/30


15/30

Re-Design with Corrosion resistant materials.

and / or

Provide an effective and durable barrier to blockmoisture, salt and oxygen from reacting with the

steel surface.

The Quest for Answers


16/30

Soft Film Barriers :

Galvanized Parts:

Aluminum Parts :Stainless Steel Parts :

Solutions to Consider :


17/30

The most common soft film barriers consist ofThixotropic over based calcium sulfonate resin withcalcium carbonate platelets, and corrosion inhibitive

pigments.These are generally soft and highly surfactantcoatings that have a greater affinity to the substratethan to itself.

This allows self Healing and moderate creep back

of damaged areas.

Soft film barrier solution


18/30

Advantages:

Relatively low cost,

More effective than alkyds, acrylics, enamels,

urethanes and epoxies in harsh environments

Remains soft and flexible

Effective at reducing corrosion undercutting

Soft film barrier solution


19/30

Disadvantages:

Can be damaged by stone impingement

Low Gloss

Attracts dirt (discolors)

Remains somewhat sticky

Requires repair / recoating when damaged.

Soft film barrier solutions


20/30

Galvanized, Aluminum, and Stainless Steel are veryeffective materials in the fight against Corrosion.

However Increased cost of using them can becomea competitive disadvantage in both manufacturingand replacing damaged parts.

Replacement Metals instead of Steel


21/30

Galvanic Corrosion can become a factor whendissimilar metals come in contact with each other.

Are your good intentions of using Aluminum,Stainless or Galvanized along with steel actuallycausing corrosion?

Galvanic Corrosion


22/30

There are three conditions that must exist for galvanic

corrosion to occur.

First there must be two electrochemically dissimilarmetals present.

Second, there must be an electrically conductive pathbetween the two metals.

And third, there must be a conductive path for themetal ions to move from the more anodic metal to the

more cathodic metal. If any one of these three conditions does not exist,

galvanic corrosion will not occur.


23/30

Prevention: Manufactures andCollision RepairShops must give serious consideration to each of thefollowing possibilities of potential cross-

contamination and make every effort to prevent itfrom happening.

Galvanic Prevention:


24/30

Provide separate areas where only aluminum isrepaired, away from steel vehicles where grinding,sanding, welding or other intensive repairs are

taking place.

Galvanic Prevention


25/30

Consider a separate set of metal working tools usedexclusively for aluminum. As a minimum, clean allhammers, dollies, cutting tools, pry bars, etc.,

before and after using on aluminum.

Galvanic Corrosion Prevention


26/30

Clean all sanding and grinding tools thoroughlyprior to use on aluminum. Always use newsanding/grinding disc, scuff pads, sandpaper, and

shop towels to avoid cross contamination.



27/30

When clamps are used, clean the jaws thoroughlybefore and after use on aluminum. The clampingarea should be wire brushed using a dedicated

stainless steel brush after removal of the clamp.



28/30

Suspension Protection


29/30

Chassis application


30/30

THANK YOU

Corrossion Cavd Ppt

Documents

Transcript of Corrossion Cavd Ppt