中北大学材料科学与工程基础试题及答案

1.The thermal behavior of solids can be represented in terms of .

A: thermal conductivity B:electrical conductivity C:dielectric constant D:elastic modulus

2. The stimulus of magnetic properties is .

A: load B: force C:electric field D: magnetic field

3. are utilized as a radial steel reinforcement in automobil

e tires, in filament-wound rocket casings, and in wire-wound high-pre ssure hoses.

A: Fibers B: Wires C: Particles D: W hiskers

16.Condensation polymerization is used in the synthesis of .

A: phenolformaldehyde B: polyvinyl chloride

C: polyethylene D: polystyrene

17. Index of and are representative optical properties.

A: load; force B: heat capacity; thermal conductivity

C:modulus; strength D: refraction; reflectivity

18. consist of a metal as the matrix, with fibers as the re inforcement medium.

A: Polymer-matrix composites B: Metal-matrix composites

C: Ceramic-matrix composites D:Carbon–carbon composites

19. The stress at fracture using this flexure test is known as the .

A: yielding strength B: tensile strength C: flexural strength D: shear strength

20.For polymers, the yield point is taken as a maximum on the curve; the stress at this maximum is the yield strength. Tensile str ength is the stress at which fracture occurs. A: metal B: ceramic C: composite D: plastic

二、名词解释（20分，每题4分）

1.Crystal

2.Thermoplastics

3. Annealing Processes

4.Specific volume

5.Homopolymer

(3) A cylindrical specimen of some alloy 8 mm in diameter is stressed elastically in tension. A force of 15,700 N produces a reduction in specimen diameter of 5×10-3mm. Compute

Poisson’s ratio for this material if its modulus o f elasticity is 140 GPa.

(4) Below, molecular weight data for a polypropylene material are tabulated. Compute

(a) the number-average molecular weight, (b) the weight-average molecular weight, (c) the number-average degree of polymerization, and (d) the weight-average degree of polymerization.