3.NF METALS

June 28, 2018 | Author: Raja Ramachandran | Category: Metals, Copper, Alloy, Tin, Bronze


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WELCOMENON FERROUS METALS METALS Metals are composed of elements having good thermal and electrical conductivity. Properties of metals - Hardness - Good thermal conductivity - Good electrical conductivity - High melting point - Strength - Stiffness -Plastic deformability - Ductile - Rigidity - Machinability - Weldability - Castability Requirement of engineering materials Fabrication: Able to get shaped easily. Service requirements: Good strength, wear and corrosion resistance. Economic requirements: Made available with minimum overall cost Selection of material Based on properties of the materials in relation to their indented use. Properties of the material - Specific characteristics of the material - Predicts the behavior of the material under different conditions. Important properties: - Mechanical properties - Electrical properties - Magnetic properties - Thermal properties - Chemical properties - Physical properties Factors for selection of the material - Ease of availability - Economy - Capacity to meet service conditions - Ease of handling - Durability Different Applications - Materials for high & Low temperature - Tool steels - Bearing materials - Spring materials - Die casting materials - Magnetic materials - Metals for nuclear energy. Classification of Metals Metals a) Ferrous b) Non – ferrous - Ceramics - Organics Non-ferrous metals: - Non-ferrous metals and alloys form an important group of materials for industrial applications. - Metals, which are not iron based. - Melting point is low. - Low strength Non-ferrous metals - Copper first invented useful metal employed by man some 15000 years ago. - They made coins, knives and spear heads Common non – ferrous metals - Copper - Lead - Nickel - Zinc - Tin - Aluminum - Magnesium - Cobalt Cu and Cu alloys • Cu 96 to 99.3 % with addition of small amounts of alloying elements such as Al,Sn,Zn,Ni,Mn & Fe copper alloys are produced. • They are based electrical conductivity,formability and corrosion resistance. Properties - Excellent resistance to corrosion - Non-magnetic properties - Easy to work, it is ductile and malleable - Moderate hardness and strength - High thermal and electrical conductivity - Resistance to fatigue, abrasion and corrosion - It can be soldered, brazed and welded COPPER - High thermal and electrical conductivity - Tensile strength 340 Newton per sq.mm - Cu is refined electrolytically - Used as conductors. Copper • To improve TS 1% Cadmium is added • Tensile strength 460 Newton per sq.mm • Used for wring purpose(lighting / telephone) • Electrical conductivity 90 % Copper • Pure copper is added with 0.50 % arsenic to increase strength at elevated temperature ( 190 to 450 ° C ) • Properties: high strength • High thermal conductivity • Used in Heat exchangers Copper alloys are used for • Electrical and electronic components • Pump impellers • Valve components • Heat exchangers • Refrigeration system • Cables & connectors • Gaskets Brass Brass is an alloy of Cu & Zn. Admiralty brass: It contains Cu 71% Zn 28 % & Sn 1%. Properties: High resistance to corrosion. High thermal conductivity Brass Uses: - Heat exchangers ( Oil / water ) - Gears & bushes - Pistons in hydraulic units - Valve spindles, bushes & gaskets - Pump impellers,sleeves & wear rings - Tools •Condenser tubes •Radiators, floats •Sheet metal parts •Architectural metal work •Water and air line fittings •Bolt , nut and wires. •Electrodes. BRONZE •It is an alloy of Cu & Zn •Low melting point •Used as bearing alloys •Accommodates misalignment •Lowers seizure of bearings •Lowers build up stresses Aluminum bronze Composition: Iron : 1 to 4 % Aluminum : 9 to 11 % Nickel : 4 % Copper : Balance Properties - Posses good tensile strength - Resistance to corrosion - Used for bearings - Hydraulic valves, piston and gears. - Valve & pump components LEADED BRASS • Cu : 62 %, Zn : 35 % & Pb : 3 % • Best suited for cold drawing • Used for making thin wires, bolts, terminals Al and Al.Alloys - Aluminum is strengthened by the addition of alloying elements such as Cu, Zn, Ni, Fe, Mn, Si and Mg. - Al.alloys can be cast, welded, forged and rolled. Properties - Light metal, density one third of steel. - Good conductor of electricity and heat - High resistance to corrosion - Ductile, non – magnetic - Melting point: 650°C. Composition TYPE METAL Cu Si Mg Zn Al I 4 3 --- --- Balance II 4.5 5.5 --- --- --do-- III --- --- 3.8 1.8 --do-- Uses • Pump & motor casings • Oil filter and cooler casings • Sky climber components • Fire fighting components • Piston & cylinder heads • Ladders & Tool • Door and window frames & patricians. • Cables. Lead and lead alloys Properties: - High resistant to corrosion - Lead can be easily soldered - Heavy weight & density - Soft and malleable - Lubricating property - Low coefficient of expansion - Low electrical conductivity USES - Used in batteries - Bearing metals - Low melting solders - Radiation protection - Fusible plugs - Crimping of wire ropes Babbitt metal - Babbitts are antifriction alloys based on either tin or lead. - Used for lining sleeve bearings - Low melting point ( 350 – 450°C ) - Heavy loaded bearings of steam turbines. Babbitt Metal Composition - Sn : 90 % - Sb : 7.25 to 8.25 % - Cu : 2.5 to 3.5 % - Heavily loaded bearings of steam turbines Properties - Good antifriction properties - Thermal conductivity is more - Good wearing property - Low coefficient of friction - To bear shocks and vibration - High resistance to corrosion Babbitt metal • Hardness of babbit metal is drastically reduced as temperature raised. • Working temperature of bearings lined with babbit should not exceed 80 ° C. Nickel Used for high temperature applications. - Hard material - High tensile strength - Moderate elasticity - Resistance to corrosion - High resistance to oxidation. Nickel – Chromium alloys are having ability to resist oxidation at elevated temperatures. Ni 75 - 80 % Cr 20 - 30 % Mn 1.5 % Maximum working temp : 1100°C •Used as heating elements •Oven and furnace. •Soldering iron. Gunmetal Tin & bronze alloy castings with Cu : 88% Sn : 10 % Zn : 2 % - High resistance to corrosion - Used in valves at water and air lines. Fusible alloys Fusible alloys: - Melts at low temperatures - Used in hydraulic couplings - Fire extinguishing sprinklers. COMPOSITION Material Melting point in ° C Bi Pb Sn Cd --- 38 62 --- 183 50 28 22 --- 96 50 24 14 12 71 UNCOMMON METALS TITANIUM • Strong, hard • More creep and fatigue properties • High resistance to corrosion • Used in creep resistant steels with Cr, Mo & V • Heat exchangers NIOBIUM • Melting point: 2468° C • High resistant to oxidation • Used in nuclear reactors COBALT • High corrosion resistant • Co- 65 %, Cr – 28 %, Mo –6 % & Ni – 1 % • High erosion resistant • Used in high speed tools • Hard facing • Gas turbine vanes. • Carbide cutting tools. THANKYOU
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