TASK. 1 a) Tensile strength: The ultimate tensile strength of a material is the maximum load that each unit of cross-sectional area can carry before it fails.tensile material impact of hammer it will be bend without breaking. b) Hardness : The hardness of a material is its resistance to wear, abrasion or indentation.a hard material is difficult to cut and very hard materials often have to be cut and polished by grinding. hard materials is makes a very much deeper indentation in the softer material. c) Toughness and Brittleness: The toughness of a material is its resistance to sudden impact and shock loading. tough materials are able to absorb the energy when something strikes them without breaking. the opposite of toughness is brittleness. d) Malleability and ductility: A material is malleable when it can easily be pressed or forged into shape. some material is malleable when cold, but others have to be heated to make them malleable. revets have to be malleable so thats their heads can be formed to shape and so does the sheet metal used to make body panels.do not confuse malleabliti with ductility.when plastic defomation occure as the result of applying a compressive load. A malleable and ductile material easy to melting and make any shape. e) Electrical conductivity: This is the ability of a material to conduct an current. most material are good conductors, whereas plastic and ceramics are bad conductors and are used as insulation materials. f) Ferromagnetism: Metals that contain large amount of iron, nickle and cobalt can generally be made magnetic. they are used to make permanent magnets and electromagnets. The latin name for iron is ferrum and these metals are said to be ferromagnetic, or to possess the property of ferromagnetism. g) Corrosion resistance: Some metals go rusty and eventually they will corrode away completely. A chemical reaction occurs between the metal, the oxygen in the air and moisture. Others are not affected very much and we say that they have high corrosion resistance. h) Solvent resistance: Some rubber and plastics are attacked by certain chemicals. we call these chemicals solvents. others materials are very stable and are not affected. we say that they have a high solvent resistance. patrol , diesel oil and lubricating oils can act as solvents a we have to be careful to select rubbers and plastics with high solvent resistance if they are going to be in contact with these substances. i) Resistance to environmental degradation: If left unprotected, wood will rot when exposed to moisture and certain plastic materials become very brittle when exposed to sunlight over a long period. wood becomes more durable when painted or treated with chemicals, plastics stay flexible for longer if coloured black. so the properties resistance capacity going more higher after use protecting substances.
Posted on: Sat, 02 Nov 2013 15:31:13 +0000