Performance

Question 1

What are the three categories of ceramics?

Answer 1

CMC - Ceramic Matrix Composites
MMC - Metal Matrix Composites
PMC - Polymer matrix composites

Question 2

Describe the following characteristics for a SiC/SiC Composite:
1. Mechanical
2. Ductility
3. Thermal Conductivity
4. Creep
5. oxidation resistance

Answer 2

1. Mechanical - variable depending on form
2. Ductility - non-brittle due to disbonding in the matrix arresting cracks. typical ceramics are brittle.
3. Thermal Conductivity - very high
4. Creep - excellent creep resistance
5. oxidation resistance - generally good, but can be a problem

Question 3

How to calculate heat transfer through refractory wall:

1. Q =
2. how to add multiple refractory thicknesses

Answer 3

1. Q = (k / x) * SA * DeltaT, where x is the wall thickness
2. When adding multiple thicknesses, the equation for k/x is 1 / [ (x1 / k1) + (x2 / k2) + … ]

Question 4

Highly alloyed steel is being austenitized, quenched, then tempered. However, the hardness and strength is not as high as it should be. What action should you take with regard to either changing the austenitizing temp or changing the quench method?

Answer 4

Increase the austenitizing temp to make sure that all carbides are dissolved. Otherwise, ferrite will nucleate at the carbide locations during quench and prevent more martensite formation

Question 5

How does distance from point source relate to radiation level?

Answer 5

radiation level is proportional to the inverse square of the distance from source

Question 6

Crack morphology of chlorides SCC

Answer 6

transgranular and branching

Question 7

crack morphology of hydrogen embrittlement

Answer 7

intergranular on high strength parts

Question 8

What metallurgy do you need to use caution with when designing for use in hydrogen environment?

Answer 8

Titanium. It becomes embrittled.

Question 9

Equation for principal stress?

Answer 9

[(stress 1 + stress 2) / 2] +/- sqrt( [(stress 1 + stress 2) / 2]^2 + shear^2)

Question 10

how do you know if something is a principal stress?

Answer 10

all shear stress related to that direction is zero

Question 11

Fatigue Life Equation based on number of cycles vs stress

Answer 11

stress = A log(N) + B, where A&B are constants and N is number of cycles until failure

Question 12

How to Estimate yield strength based on vickers hardness?

Answer 12

HV/3 = YS
must convert HV into Mpa

Question 13

What are units of a pascal?

Answer 13

N/m^2