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Wear Mitigation by the Use of Surface Coatings

Wear Mitigation by the Use of Surface Coatings. by Stephen Huse. Outline. Abrasion and adhesion description Variables that change the wear rate Variables changed by coatings Surface coating processes Physical Vapor Deposition (PVD) Chemical Vapor Deposition (CVD) Electrodeposition

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Wear Mitigation by the Use of Surface Coatings

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  1. Wear Mitigation by the Use of Surface Coatings by Stephen Huse

  2. Outline • Abrasion and adhesion description • Variables that change the wear rate • Variables changed by coatings • Surface coating processes • Physical Vapor Deposition (PVD) • Chemical Vapor Deposition (CVD) • Electrodeposition • Thermal Spray

  3. Abrasion • Physical interference of surface asperities • Types: • Cutting • Cracking (brittle fracture) • Ploughing

  4. Adhesion • Cold weld of surface asperities • Similar materials such as steel on steel • Wear removes oxide layer

  5. Variables That Change the Wear Rate • Friction • Surface roughness • Normal Forces • Temperature • Surface hardness • Surface materials • Environmental considerations

  6. Variables Changed by Coatings • Surface Hardness • Reduces abrasive wear • May increase brittleness • Friction • Reduces force for tooling • Reduce heat generated • Surface Materials • Reduces adhesive bonding • Example: steel - steel becomes steel - ceramic coating - steel

  7. Physical Vapor Deposition Process • Vacuum environment • coating powder is melted and transported to substrate • Cathodic arc • Electron beam • Plasma torch • Magnetic • Coating condenses on substrate • NASA plasma spray PVD • Advantages • High Hardness • Low friction • Disadvantage: requires line-of-sight

  8. Chemical Vapor Deposition Process • Chemically controlled atmospheric environment. • Substrate heated to 2000°F • Atmosphere chemically reacts at surface • Examples: • Titanium cloride (gas), nitrogen, and hydrogen → titanium nitride coating • Titanium chloride (gas), methane, and hydrogen → titanium carbide coating • Superior adhesion of the coating to the substrate • Used for synthetic diamond growth

  9. Electrodeposition • Example: Chrome plating • Resists corrosive wear • Increased hardness • Reduced friction Thermal Spray • Example: Plasma spray • Similar to PVD, but no vacuum • Substrate is preheated to remove impurities

  10. References • http://www.diamondtc.com/diatiger/about.html • http://www.Gordonengland.co.uk • http://www.signalplating.com • http://www.sulzer.com • http://www.surface.mat.ethz.ch • http://www.pall.com • http://www.manmadediamondinfo.com • http://www.ptli.com • http://www.directindustry.com

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