tailieunhanh - Mechanical Engineers Data Handbook Episode 11

Tham khảo tài liệu 'mechanical engineers data handbook episode 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 240 MECHANICAL engineer s data handbook Properties of pure metals Metal . C p kgm 3 E GNnT2 G GNm 2 RSHC a xio6 c- Po lơtíì-m ar mfiT-1 ECE mg c-1 Aluminium 659 2700 70 27 23 245 450 Copper 1083 8900 96 38 17 156 430 Gold 1063 19 300 79 27 14 204 400 Iron 1475 7 850 200 82 12 890 650 Lead 327 11 370 16 29 1900 420 Mercury 13 580 60 9410 100 Nickel 1452 8 800 198 13 614 680 Platinum 1775 21040 164 51 9 981 390 Silver 961 10 530 78 29 19 151 410 Tungsten 3400 19 300 410 490 480 Zinc 419 6860 86 38 30 550 420 . melting point p density E Young s modulus G shear modulus RSHC relative specific heat capacity a coefficient of linear expansion p resistivity at o c Ct resistance temperature coefficient at o c ECE electrochemical equivalent. Corrosion of metals Corrosion prevention Corrosion may be prevented by considering the following points. Material selection Metals and alloys which resist corrosion in a particular environment can be used. Proximity of metals with large potential difference . a copper pipe on a steel tank should be avoided. Galvanic protection can be used . by use of a sacrificial anode of zinc close to buried steel pipe or a ship s hull. Appropriate design Crevices which hold water . bad joints and incomplete welds should be avoided as should high tensile stresses in material subject to stress corrosion. Locked-in internal stress due to forming should be avoided. Modified environment Metals can be enclosured against a corrosive atmosphere water etc. Drying agents . silica gel and corrosion inhibitors . in central-heating radiators can be used. Protective coating Metals can be coated to make them impervious to the atmosphere water etc. by use of a coating of grease plasticizer bitumen resins polymers rubber latex corrosion-resistant paints or metal coating. Corrosion resistance of metals .