# t4f07 - MAT 200 Test#4 ID Number This is a closed book test...

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MAT 200 Test#4 ID Number ____________________________________________ This is a closed book test. No notes, books, or information stored in calculator memories may be used. Cheating will be punished severely. All of your work must be written on these pages and turned in. Units must be shown. Be sure that you read and answer all parts of each question. Using a pencil, fill your answers on the scan sheet after you complete the exam and return the scan sheet along with your answers to the examination questions. Equations or constants required for this test. Formulae: σ = σ o exp(- τ/τ r ), τ r = τ ro exp(Q/kT), η = η o . exp(Q/kT), 1/E c = V f /E f +V m /E m E c = V f E f +V m E m ρ c = V f ρ f +V m ρ m 1/ρ c = V f / ρ f +V m / ρ m o.155<ratio<0.225 CN=3 0.225<ratio<o.414 CN=4 0.414<ratio<0.732 CN=6 0.732<ratio<1 CN=8 All questions carry 2 points. Q1 . ___b___1. When modifiers like Na 2 O are added to network formers like SiO 2 , the Na atoms go into a. the network b. holes in the network c. both a and b d. neither a nor b __c____2. The principle test method for estimating the strength of a ceramic is the a. impact test b. tensile test c. flexural test d. a large stress/strain ratio __b____3. When testing a ceramic or glass sample, tests are always performed a. on a single good sample b. on a group of samples to determine the statistical variation 1

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c. on a group of samples of different sizes to determine the effect of size d. on a group of samples to determine the compositional variation _c_____4. The coordination of the cation in an ionic ceramic structure depends on a. the density b. the charges on the ions c. the ratio of the cation to the anion radii d. none of the above ____c__ 5. Processing of ceramic particulate composites such as WC-Co is carried out by a. pressing the powder to form a green compact b. casting the molten components c. pressing the powder to form a green compact and sintering d. deforming the green compact to the proper shape b______6. A thermoplastic polymer can be made stiffer (the modulus can be increased) by a. heating it above the Tg b. increasing the amount of cross-linking and branching c. decreasing the amount of cross-linking d. none of the above d______7. Stress relaxation observed in polymers arises because a. dislocations move easily b. covalent bonds are broken c. the temperature is below Tg d. polymer molecules slide past one another __c____8. Thermoplastic polymers differ from thermosetting polymers in that a. they cannot be crystalline b. they are not recyclable c. they have a linear molecular structure (as opposed to cross-linked or network) d. all of the above ___b___9. . The nonlinear elastic behavior of an elastomer arises from
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t4f07 - MAT 200 Test#4 ID Number This is a closed book test...

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