材料科学与工程代写 MECH 210代写材料学代考材料学代写

2023/06/12材料学代写考试助攻 MECH 210代写材料学代写材料学代考材料科学与工程代写338

MECH 210 – Materials Science and Engineering

Final Exam

材料科学与工程代写 I. Answer the following questions. (20 points) a. What is the primary type of bond in the backbone of polymer molecules?

I. Answer the following questions. (20 points)

a. What is the primary type of bond in the backbone of polymer molecules?

(A) ionic bond (B) covalent bond (C) van de Waals bond (D) metallic bond – – – – – – – – – – – – – – – – – – – – – _____

b. Dissolving 100 grams of nickel in 0.5 liters of water makes a molar concentration of

(A) 2.1 M (B) 1.5 M (C) 0.5 M (D) 3.4 M – – – – – – – — – – – – – – – – – – – – – – – – – – – – – – – – – – _____

c. The molecular weight of polyethylene -(C2H4)-n of degree of polymerization of 2000 is

(A) 56,100 g/mol (B) 52,350 g/mol (C) 59,750 g/mol (D) 46,340 g/mol – – – – – – – – – – – – – – _____

d. The equivalent number of atoms in FCC unit cell is (A) 4 (B) 3 (C) 6 (D) 2 – – – – – – – – – – – – – _____

e. Which crystal structure has the smallest number of slip systems? (A) FCC (B) BCC (C) HCP – – – – – – – _____

f. Which hardness number relates directly to tensile strength of steels? (A) Rockwell hardness number (B) Vickers micro-hardness number (C) Brinell hardness number (D) Scleroscope hardness number – – – – – – – – – – – – – _____

g. S-N curve is determined in what test? (A) tensile (B) fatigue (C) Jominy hardenability (D) impact – – – – – – – – _____

h. Which processing method can increase strength without sacrificing too much ductility? (A) precipitation hardening (B) cold work (C) annealing (D) grain size refinement – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – _____

i. Ductile-to-brittle transition temperature is determined by conducting (A) tensile tests (B) hardness tests (c) fatigue tests (D) impact test s – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – — – – – – – – – – – – – – – – – – _____

j. Which of the following microstructures is that of grey cast iron? – – — – – – – – – – – – – – – – – – – – – – – – – – – – – – _____

k. What are the conditions for the “Standard emf Series” ? _______________________________________________

l. Which polymerization process generates by-products that are usually removed from the product? _____________

m. What is oxidation of polymers? ___________________________________________________________________

n. What kind of reaction takes place at cathode in a galvanic cell? _________________________________________

o. What is stress relaxation of polymers? _____________________________________________________________

p. What is isostress loading in fiber composites? ________________________________________________________

q. What is specific gravity? _________________________________________________________________________

r. The function of electrolyte in electrochemical corrosion is ______________________________________________

s. Coin and button battery cells are electrochemical cells. As shown in the figure, what important component(s) necessary for an electrochemical cell to function is (are) missing?

_______________________

t. When steel pipes are connected with copper couplings, which will be corroded? ____________________________

II. 材料科学与工程代写

When pure Ni and Fe are in contact forming an electrochemical cell under standard conditions, (20 points)

(i) which metal will be oxidized? _________________,

(ii) the spontaneous reaction of the electrochemical cell is __________________________________________,

(iii) electron migrate from ____________ to _____________,

(iv) what is the overall electrode potential for the electrochemical cell? (show calculation).

III.

For the Fe-Cd electrochemical cell shown, determine (a) the overall electrochemical cell potential and (b) the spontaneous overall reaction of the cell. (20 points)

IV.

How much sulfur, in grams, will be needed to vulcanize 15 kg of polychloroprene using 6% of possible crosslinking sites? On average, there are two sulfur atoms at each established crosslink. (20 points)

V. 材料科学与工程代写

A carbon fiber-reinforced nylon 6,6 composite having fiber volume fraction 0.45 is subjected to tensile load as shown Determine (a) the stress developed in fibers and (b) the strain of the composite along the direction of applied load. (20 points)

Standard emf Series

Reduction Reaction	Standard Electrode Potential, V^O (V)	Reduction Reaction	Standard Electrode Potential, V^O (V)
Cu²⁺ + 2e^– ® Cu	+0.340	Cd²⁺ + 2e^– ® Cd	-0.403
Ni²⁺ + 2e^– ® Ni	-0.250	Fe²⁺ + 2e^– ® Fe	-0.440

Material Properties 材料科学与工程代写

Material	Modulus of Elasticity, GPa	Tensile Strength, MPa	Density, g/cm³	Atomic Weight, g/mol
Carbon	—–	—–	2.25	12.011
Chlorine	—–	—–	—–	35.45
Hydrogen	—–	—–	—–	1.008
Iron	—–	—–	7.87	55.85
Sulfur	—–	—–	2.07	32.06
Carbon fiber	260	4,000	1.80	—–
Nylon 6,6	2.80	76	1.14	—–