Wear

Question 1

Lubrication examples

Answer 1

1) solid lubricants - high temp, sealed units + vacuums.
2) hydrodynamic lubrication
3) boundary lube

Question 2

Erosion

Answer 2

Similar to abrasive wear but;

1) strain rates much higher (liquid drops -> Severe erosion espec on brittle)
2) fluid dynamics of gas/liquid flow may be important
3) angle of i in important variable

Question 3

Erosion of ductile materials

Answer 3

K depends on materials ductility + hardness

V. Low i = ploughing
Low i = machining
High i = indenting

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Question 4

Mild wear

Answer 4

• wear of oxide film on each contacting surfaces
• material loss after plastic flow
• “ “ W/oxidation/chemical attack
• lubricated or unlubricated

Question 5

Steps of material loss due to fracture aspersores after ?

Answer 5

1) asperity contact + junction formation
2) fracture of one side of junction + material transfer
3) secondary asperity contact -> loss of material

Question 6

Severe wear

Answer 6

• material loss after plastic flow (metals) - can be abrasive or non
• “ “ By fracture w/no plastic flow (ceramics) - abrasive

Question 7

Example of solid lube

Answer 7

Graphite, MoSi2, PTFE

Nylon, PEEK