PROCESS AND EXPERIMENTAL INSTALLATION FOR PRODUCING POROUS ALUMINIUM ALLOYS WITH REDUCED SPECIFIC WEIGHT

The invention relates to a process and an installation for preparing porous aluminium alloys with reduced specific weight by treatment with stabilizing elements and by blasting gas into the melting charge. The claimed process for preparing AlSi12Ca1.5Mg alloy with a high porosity of 20...30%, an apparent density of 1.8...2.2 g/cmand a pore size of 300...500 μm, uniformly distributed in the alloy, consists in melting the AlSi12 alloy, after which the temperature is raised to 650°C, the AlMg10 pre-alloy is added for generating small size oxide particles with low surface tensions which stabilize the metallic foam, 3...5% metal Ca is added while stirring, in order to obtain thermodynamically stable oxides and increase the viscosity of the melting charge, the melting charge is kept for homogenization for 10...15 min and then gaseous nitrogen is bubbled at temperatures of 650...700°C at time intervals of 5 min, the metallic foam formed at the surface of the melting charge is collected and the porous material is solidified at the ambient temperature. The claimed installation comprises a vertical electric furnace () with a dense graphite crucible () built for injecting the gas to the bottom part, a mechanical stirrer () made of dense graphite built from a long rod provided with a screw and a gas bubbling device () placed at the bottom part of the crucible (), consisting of a leading tube and a porous plug of ceramic material with a pore size smaller than 1 mm. Invenţia se referă la un procedeu şi la o instalaţie pentru obţinerea unor aliaje poroase de aluminiu, cu greutate specifică redusă prin tratare cu elemente stabilizatoare şi insuflare de gaz în topitură. Procedeul conform invenţiei, pentru obţinerea unui aliaj AlSi12Ca1,5Mg cu porozitate înaltă de 20...30%, densitate aparentă de 1,8...2,2 g/cmşi dimensiunea porilor de 300...500 μm repartizaţi uniform în aliaj, constă în topirea aliajul AlSi12, se ridică temperatura la 650°C, se adaugă prealiajul AlMg10 pentru apariţia particulelor oxidice de dimensiuni mici şi tensiuni superficiale scăzute, care stabilizează spuma metalică, se adaugă 3...5% Ca metalic sub agitare, pentru obţinerea oxizilor stabili termodinamic şi creşterea viscozităţii topiturii, se menţine topitura 10...15 min, pentru omogenizare, apoi se barbotează azot gazos la temperaturi de 650...700°C, la intervale de 5 min, se colectează spuma metalică formată la suprafaţa topiturii, şi se solidifică materialului poros la temperatură ambiantă. Instal