Transcript Project presentation.pptx

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
 Thermal Spray
Abrasion
 Physical interference of
surface asperities
 Types:
 Cutting
 Cracking (brittle fracture)
 Ploughing
Adhesion
 Cold weld of surface
asperities
 Similar materials such as
steel on steel
 Wear removes oxide layer
Variables That Change the Wear
Rate
 Friction
F


N
f
s
,
k
 Surface roughness
 Normal Forces
 Temperature
 Surface hardness
 Surface materials
 Environmental considerations
V KN

L
H
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
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
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
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
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
End