5 Surface Engineering, Weldign And Joining

Question 1

What are the two main types of surface treatment

Answer 1

Surface modification and surface coating

Question 2

6 reasons for surface treatment

Answer 2

Wear resistance
Fatigue life 
Corrosion resistance
Friction control
Aesthetics
Functional properties ie electrical/thermal conduction

Question 3

Two types of surface modification

Answer 3

Composition unchanged eg transformation hardening

Composition changed eg carburising/nitriding of steels

Question 4

What are the two characteristic diffusion distances in austenite formed from ferrite and pearlite

Answer 4

within prior pearlite regions, between the high/low carbon regions
that were previously iron carbide and ferrite: around 0.5 micro m

diffusion between high C austenite grains (former pearlite), into low C 
austenite grains (initially ferrite): around 20 micro m

Question 5

3 main types of joining processes

Answer 5

Mechanical, welding and Solid State

Question 6

3 things to consider when choosing a type of joining

Answer 6

Materials to be joined
Geometry of the joint
Mode of loading on the joint

Question 7

What type of joints is adhesive bonding best for

Answer 7

Lap joints, as adhesives are much stronger in shear than in tension.

As the two materials are isolated from one another, it’s a good method for joining dissimilar materials