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27 May 2015

Material Science Useful Questions & Answers

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The Important Question and Answers for DAE, B.Tech and B.E

Q. What is refining process?
Ans. After extraction of metals, refining is done to obtain it more purer form. As for example, after electrolytic refining. We get 99.99% pure copper.
Q What is dross?
Ans Dross is a term used for the oxides of metals. 
Q Define plastics
Ans plastics are mouldable synthetic organic resins characterized by plastic deformation, under stress. It is mainly of two types.
(a) thermosetting plastic
(b) thermoplastic plastics
Q What are thermosetting plastics?
Ans these plastic are shaped by the application of heat with or without pressure. It is becoming permanently hard by  the polymerization. And can’t be re softened by a heat. Common the thermosetting compound are of phenol formaldehydes, urea formaldehyde, phenol formaldehyde and the melamine. 
Q what is Bakelite?
Ans Bakelite is plastics of phenol formaldehyde group.
Q Define thermoplastics?
Ans thermoplastic don’t undergo any chemical change during mould. It doesn’t become permanently hard with the application of pressure and heat these particles may be remelted repeatedly for further moulding. 
Example, Cellulose derivatives and polystyrenes polyethylene vinyl resins acrylic resins 
Q What are P.V.C plastics?
Ans PVC stands for poly-vinyl chloride, which is used for protective coatings for food and chemicals cover of electric cables gramophone recodes water tubes 
Q What is glass?
Ans glass ids a hard, brittle, transparent non-crystalline solid material. It has good corrosion resistance. Aced, base and salt resistance and electrical current resistance. 
Q` what is epoxy cement?
Ans It is used for joining plastics, wood and sheet metals. The surface to be joint is generally very small and makes a hard and tough joint.
Q What is glass wool?
Ans It is glass (alumina boro-silicate) in fibrous from. It has good resistance to heat and sound.
Q Define pyrometer.
Ans Pyrometer is a device or instrument to measure high temperature.
Q What is the difference between the thermometry and the pyrometer?
Ans both are techniques to measure temperature generally refers with the temperature measurements with mercurial thermometer up to 350oC. Pyrometer deals with the measurement of high temperature.
Q What are non-ferrous metals?
Ans Metal other than iron re called non-ferrous metals
Q Mention few important non-ferrous alloys
Ans few important non-ferrous alloys are brass, bronze, duralium, gun-metal, muntz-metal, rolled gold, germen silver, invar, Hindalium 
Q What are the main uses of copper?
Ans It is used mainly for making electric wire, sheers, utensils, coins, electroplating, making alloys 
Q Why copper is used for electrical purpose?
Ans Due to its high conductivity value. It is suitable for electrical purposes 
Q What are the furnaces, which can melt copper and copper alloys?
Ans Crucible furnaces, reverberatly furnace, induction furnace and electric arc furnace are suitable furnaces for remelting of copper and copper alloys 
Q Can copper be welded?
Ans Yes
Q What are main steps in production of copper from Its sulphide ore by pyrometallurgieal process?
Ans Main steps of production are as follow in given sequence 
Concentration of ores Roasting Smelting  Refining 
Q Why roasting of copper sulphide ore is done?
Ans The object of roasting copper sulphide ore to oxide copper sulphides. This causes reduction of sulpher content of the charge makes suitable metal for smelting. 
Roasting is not required for the ores which contain just sufficient amount of sulpher to make a suitable grade of metal 
Q Why smelting is roasted copper ore is done?
Ans In smelting operation roasted copper ore is fused to make a molten slag which constitutes gangue material and impurities the product of smelting is copper metal 
Q What is the purity obtained after electrolytic refining of copper?
Ans The purity of copper comes up to 99.99%
Q Which type of copper ore is processed by hydrometallurgical process?
Ans Hydrometallurgical process of copper extraction is suitable for its oxide ore. 
Q What is principle of the hydrometallurgy?
Ans Hydrometallurgy involve the separation of metal in aqueous solution from the rest of the ore followed by precipitation in metallic form. Separation of soluble substance from an insoluble one is done by mean of a solvent either water or some solution.
Q Define a mould
Ans A mould contains a cavity, in which molten metal is poured. It also contained sprue, gates, risers, runner etc
Q What are different mould material?
Ans Mould are made of different material such as moulding sand, plaster, ceramics, wax, metals, depending upon the casting process.
Q What is role of venting in the mould?
Ans Venting are made to escape gasses evolved during pouring of molten metal into the mould.
Q What are different grain shapes of foundry sand?
Ans different grain shapes of foundry sands are round, sub-angular, angular and compound.
Q Which type of sand grain provides maximum permeability in the mould?
Ans Mould made of rounded grains provide maximum permeability
Q What should be the amount of silica in a good foundry sand?
Ans The good foundry sand should contain more than 98 percent silica.
Q What types of castings are produced by pit moulding.
Ans Heavy or bigger castings are produced by pit moulding
Q What is jolt machine?
Ans In jolting machine the mould box or flask placed on the match plate is filed with sand and sand and is mechanically raised and dropped repeatedly. Due  to sudden change in intertia, the sand gets packed and rammed 
Q What is squeeze machine?
Ans In the squeeze machine, the mould box or flask filled with sand is squeezed against as pressure board, which compacts the sand. The pressure is applied pneumatically or hydraulically 
Q What is the use of core?
Ans Core is used to make hole, recesses, projects pars or interior contour of the casting.
Q What is core print?
Ans The projected part of core which is fixed it the mould is called core print, core print helps not to float or buoyancy up the core during the pouring of molten metal in the mould cavity
Q What is sprue?
Ans Spures is vertical portion of the gating system and as just pouring cup 

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