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Material Science - short answer questions from AMIE exams

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If G = 130 GPa for a metal and Poisson's ratio = 0.3, calc ulate the value of E for the metal. Modulus of elasticity (E) = 45 MPa, and Poisson's ratio (μ) = 0.31   The relation between Elastic modulus and Poisson's ratio and Modulus of rigidity is given as:   E = 2G(1 + μ)     ⇒ 130 = 2 × G (1 + 0.3) From this, G = 50 GPa Stainless steels (an alloy of iron, a = 0.2867 nm) always can contain a huge amount of chromium. (a = 0.2885 nm). Explain. From the given lattice parameters (a) the corresponding radii for iron and chromium are 0.124 nm. and 0.125 nm which are nearly the same so can easily form the crystal bonding. Stainless steel contains about up to 11% chromium. Define isomorphous systems with examples. The term isomorphous system is related to phase diagram, isomorphic means having the same crystal structure or complete solubility for all compositions. The copper-nickel system is an example of an isomorphous system. A pure copper wire has been drawn at a temperature of

Material Science - short answer questions from AMIE exams

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Why are cutting tools manufactured from high-carbon steel in preference to low or medium carbon? High carbon steels contain more carbon and are therefore harder both initially and after heat treatment. In most instances, the cutting tool must be harder than the material being cut. Suggest whether low, medium or high-carbon steel should be used for the following applications.  nails  ball bearings car bodies crankshafts heat-treatable machine parts drills Low High Low Medium Medium High. State whether the carbon contents below relate to low,  medium or high carbon steels. 0.29%  0.65% 0.87% 0.08% 1.32% 0.31% 0.59% Low High High Low High Medium Medium In which way does the normalising treatment differ from the annealing treatment.  The only difference between annealing and normalising treatments is the way in which they are cooled. Material that is being annealed is cooled in the furnace whilst normalising cooling is done in still air. Explain case hardening. Case-hardening is a method o

Material Science - short answer questions from AMIE exams

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Name two important ceramic insulators with their properties. Porcelain is the most frequently used material for insulators. Insulators are made of wet, processed porcelain. The fundamental materials used are a mixture of feldspar (35%), china clay (28%), flint (25%), ball clay (10%), and talc (2%). Toughened glass is also frequently used for insulators. The melted glass is poured into a mould to form the shell. Dipping into hot and cold baths cools the shells. Write the scientific names of the following polymers with one of their typical use: Teflon, ABS. Teflon: PTFE (polytetrafluoroethylene) ABS: Acrylonitrile - Butadiene - Styrene Teflon-PTFE is a Polytetrafluoroethylene used in GoreTex and nonstick cookware, and also as a high-frequency, high-temperature dielectric/insulator for electrical wires and coaxial cables.  ABS is an ideal material wherever superlative surface quality, colour fastness and lustre are required. ABS is a two-phase polymer blend. A continuous phase of styrene

Material Science - short answer questions from AMIE exams

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Suggest one suitable material for each of the following purposes with justifications: File cabinet Water tap Manhole cover Garden chair Glass cutter A suitable material is Steel, board   brass   cast iron    Wrought iron, concrete, bamboo, timber    Low alloy steel Atomic radii of two metal atoms are 0.128 nm and 0.133 nm respectively. Find out whether they form a solid solution, and if they form, state what type of solid solution it is. They will form substitutional solid solutions because the sizes of atoms are nearly the same. Atomic radii of two metal atoms are 0.1278  nm (Cu) and 0.1431 nm (Al) respectively. Find out whether they form a solid solution, and if they form, state what type of solid solution it is. Only 20% of copper atoms can be replaced by aluminium because there is a substantial difference in size.   Write down the slip plane and slip direction (one plane and one direction) of Nickel (only Miller indices). How many slip systems are there in Nickel?  Why has ferrite

Material Science - short answer questions from AMIE exams

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A brass plate contains a steel screw and it is being used in a marine environment. Which of the two metals would corrode faster and why? The steel is on the higher side of the Galvanic series as compared to brass, so it will corrode faster. What is the weight % of carbon in low carbon steel? The percentage of carbon in low carbon steel is 0.05 to 0.3. What is carburizing? Carburizing is the diffusion or impregnation of carbon on the surface. Whether duralumin is wrought or cast alloy? It is a wrought alloy. Name at least two mechanisms of plastic deformation. Slip and Twinning. The key difference between slip and twinning is that during a slip, all atoms in a block move the same distance whereas, in twinning, the atoms in each successive plane in a block move through different distances that are proportional to their distance from the twinning plane. Which of the two main mechanisms of plastic deformation requires greater shear stress to deform. Slip If you wound annealed MS and copper

Material Science - short answer questions from AMIE exams

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If we test a cast-iron sample in tensile mode, will there be any appreciable plastic deformation? Why? Very small plastic deformation is associated with the tensile test of C.I. because it is brittle. For which type of fracture, the direction of crack motion is very nearly perpendicular to the direction of the applied tensile stress? The direction of crack propagation is nearly perpendicular to applied tensile stress in Brittle fracture.  Which alloying element is most important to make steel corrosion-resistant and what is the minimum percentage of this element required? To shape steel corrosion-resistant chromium is added with a minimum of 0.7%. Every plastic is polymer but every polymer may not be plastic. Is it true? Justify. The statement is true.  All polymers are not plastics, but all plastics are polymers. For instance, cellulose is a polymer; but, it cannot be processed in the same way as a plastic material unless it is modified. Polymers can exist organically or be created sy

Material Science - short answer questions from AMIE exams

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Cup and cone type of fracture is characteristic of which type of material? Cup and cone fracture is characteristic of moderately ductile material. The formation of the cup and cone fracture surface occurs in stages. Initially, as a result of the tensile load, the material stretches and experiences plastic deformation. Beyond some point, the material will begin to neck . Which two parameters constitute a slip system? Slip plane and slip direction constitute slip system. What is the essential difference between a brittle fracture and a ductile fracture? Little or no plastic deformation in brittle fracture and large plastic deformation in ductile fracture. Is it possible to determine stress in a body without measuring corresponding strain? Yes by measuring force and area. What is the essential difference between thermoplastic and thermoset polymers? Thermoplastic polymer softens on heating while thermosetting sets or hardens. What are the three stages of creep deformation? Decreasing rate