Q. Describe two major product applications of powder metallurgy.
Ans. Following are some typical applications of powder metallurgy.
(i) Refractory metal : Production of refractory metals such as tungsten, columbium and molybdenum, both hot and cold pressed.
(ii) Cemented carbide tools and dies : Fabrication of cemented carbides of different grades such as
(a) WC + CO (b) WT1C2 + CO
(c) WC + T1C2 + CO (d) WC + N1
(e) WC + Pt
(iii) Non-ferrous bearing : In making non-ferrous bearings for automotive applications such as clutch, thrust bearing transmission and generator bearings, gear pumps, rotots, etc. impregnated with lubricants for long service-free life.
(iv) Electrical and magnetic parts : Production of electrical and magnetic parts such as alnico magnets content points, motor brushes made from powders of copper and graphite, cores for induction coils etc and the new ceramic types of magnets.
(v) Machine components : Fabrication machine components such as gears, clutches, cams, brackets and even complex details of almost any piece of machinery.
(vi) Metal filters : Porous powder metal components such as filter elements made from bronze, nickel and stainless steel powder, which make possible filtering, diffusing and controlling flow of gases and liquids, separating liquids having different surface tension and removing moisture from air streams.
(vii) Motor brushes : The copper and graphite powders are used to make motor brushes.
(viii) Production of Ceramic : These are combination of metals and ceramics having the strength, toughness and thermal shock resistance of metals and the abrasion and heat-resistance of ceramics e.g. Al2O3 - Cr.
(ix) Corrosion resistant apparaturs : Fabrication of corrosion resistant chemical apparatus, nuclear energy equipment, systems for handling rocket fuels, ramjet nozzles, cutting tools and crucibles for highly reactant materials.
(x) Welding electrodes and flam cutting : Large quantities of powder iron are used in the manufacture of electrodes for arc welding, powdered iron is also used for flame cutting.
(xi) Nuclear reactor fuel elements : Fuel plates are fabricated from uranium aluminide powders in dispression type aluminium clad fuel elements. This fuel plates are used in the preparation of fuel element for high flux nuclear reactors.
(xii) Heavy metal alloys : Development of ductile tungsten base heavy metal alloys made by P/M technique is used as counter weights for self winding wrist watches, gyro-rotos, etc.
(xiii) Clutch facing and brake linings : Other applications of P/M techniques include manufacture of ball retainers and diamond impregnated tools, use of metal powders in paint pigments and preparing friction surfaces for clutches, brakes and other devices.
Some typical applications of metal powders are shown in Table.
Table : typical applications for metal powders
Applications Metals Uses
Abrasives Fe, Zn Cleaning, abrasive wheels
Aerospace Al, Be, Nb Jet engines, heat shields
Automotive Cu, Fe, W Valve inserts, bushings, gears
Electrical/electronics Ag, Au, Mo Contacts, diode heat sinks
Heat treating Mo, Pt, W Furnace, elements, thermocouples
Joining Cu, Fe Solders, electrodes
Lubrication Cu, Fe, Zn Greases, seals
Magnetic Co, Fe, Ni Relays, magnets
Medical/Dental Ag, Au, W Implants, amalgams
Metallurgical Al, Ce, Si Metal recovery, Alloying
Nuclear Be, Ni, W Shielding, Filters, reflectors
Office equipment Al, Fe, Ti Copies, Cams