METHOD FOR MAKING POROUS SEMIFINISHED PRODUCTS OF ALUMINIUM ALLOY POWDERS Russian patent published in 2003 - IPC

FIELD: powder metallurgy, possibly manufacture of porous materials having good heat and sound insulation properties, energy absorption property and light weight, inflammability and ecological safety. SUBSTANCE: method comprises steps of mixing powders of aluminium alloys with blowing agents having decomposition temperature more than melting temperature of aluminium alloy powder; pouring prepared mixture to vessel; heating vessel with powder mixture; then performing hot compaction, cooling and further high temperature treatment; secondary cooling; mixing aluminum alloy powder with blowing agents at adding powders of aluminium oxide and hydroxide in quantity 1 - 10 %; or mixing blowing agent and aluminium oxides and broken particles (with fraction size 0.5 -0.45 mm) of secondary selected aluminium alloy in attrition device for preparing mechanically alloyed powder alloy; heating mixture in inert atmosphere (argon, nitrogen, dew point 40 C); pouring powdered mixture into vertically arranged vessel providing simultaneous vibration compaction and keeping temperature of powder mixture; feeding it to rectangular roll grooved pass of powder rolling mill in which depending upon change of stress deformation state continuous hot compaction or pressing is performed in closed grooved pass of horizontally arranged rolls at temperature 430-500 C at salifying mathematical relation: H = h×γ×d, where H is roll gap, mm; γ- is coefficient of compaction of powder or metallic particles; α- is experimental coefficient, when it is in range α>1,0-mixture is undercompacted (density 0.86-0.95%), when it is in range 1,0≥α≥2,0, state of hot compacted hard-to-form powders and particles corresponds to density 0.97-0.99%; when it is in range 1,5≥α≥4,5, state corresponds to hot pressed continuous strip with width 150-2000 mm; cutting strip by blanks; placing them in temperature controlled multiple-use holders whose lateral surfaces are made of heat insulation material with blackness degree significantly different from that of melt aluminium; heating holder with blank until liquid temperature of powdered alloy (until melting alloy); according to visually observed stripe of liquid aluminium over edge of holder determining height of frothing and interrupting free frothing at predetermined level. EFFECT: enhanced efficiency, loss free production process, lowered cost price of semifinished products. 13 cl, 1 dwg, 4 ex