Produção de compósito de matriz de alumínio com reforço de aço 1045 a partir de resíduos via metalurgia do pó

Abstract

The continuous extraction of ores and the production of metals create a great environmental impact due to the high energy consumption and the large generation of waste. Powder me- tallurgy is an efficient and economical manufacturing process that can be used to reuse metal chip, waste that is difficult to be recycled. Based on this, this work developed, based on diffe- rent types of waste, a metallic composite applying powder metallurgy as a manufacturing pro- cess. Different sources of raw material were used to make the composite. For aluminum beve- rage cans and chips from frame machining. For the steel SAE 1045 steel chips and a 1045 steel composition made from powdered iron and powdered graphite were used. The cans were cut with dimensions between 5 and 10mm and the chips were obtained through machining. The material was subjected to high-energy millings with samples containing 80% aluminum and 20% 1045 steel. Two different manufacturing processes were used, basically differing in terms of the compaction temperature. In the process that used compaction at room temperature, there is only

one compaction step, followed by a controlled atmosphere sintering at 1200oC for 1h. The pro- cess that used hot compaction, consists of two compaction stages: a pre-compaction at room temperature followed by heating up to 500oC and a subsequent compaction with the part still heated. After cooling, the parts underwent heat treatment. The samples were characterised by optical microscopy, scanning electron microscopy, X-ray diffraction and microhardness mea- surements. Measurements of density was also made. It is possible to observe that, based on the results obtained in the experimental procedure, the samples compacted at room temperature and sintered showed excessive oxidation and fractures, making it impossible the identification of microstructures. In the samples that underwent hot compaction, a material well consolidated was formed since the correlation between experimental and theoretical density showed a value superior to 98%. It was also observed the formation of an intermetallic phase with high hardness. Thus, it can be concluded that it is possible to develop a composite using only scraps of alumi- num and steel, processed by powder metallurgy, using hot compaction, and achieve satisfactory results.