Preparation of Al₂O₃–AlN–Ni Composites

Abstract

A method is proposed to prepare Al 2 O 3 -AlN-Ni composites. The composites are prepared by sintering Al 2 O 3 /NiAl powder mixtures at 1600°C in a mixture of nitrogen and carbon monoxide. The presence of NiAl particles raises the green density of Al 2 O 3 /NiAl powder compacts. During sintering, NiAl reacts with nitrogen to form AlN and Ni inclusions. A volume expansion accompanies the reaction. Because of the high green density and the reaction, the volume shrinkage of the Al 2 O 3 -AlN-Ni composite decreases with the increase of added NiAl content.

Fabrication of MMCs from metal and alloy powders produced from scrap

“…1) may act as a contributing factor in the green strength of the pressed powders due to particle interlocking [14]. The difference in particle sizes for the metallic powders versus the fine ceramic has also been reported as another parameter leading to more efficient particle packing [15]. Besides, the very fine zinc stearate powder (lubricant) that was necessary to use in the case of the Ni 3 Fe-based compacts seems to contribute to an increased relative green density in comparison to the (3Ni + Fe)-Al 2 O 3 compositions where no lubricant was demanded.…”

Porous Ni/ZrO2 Cermet from Highly Concentrated Composite Colloid

“…[2][3][4][5][6][7][8] In view of the literature, such metal/ceramic combinations include materials of a broad spectrum, e.g., molybdenum/mullite, 1 stainless steel/carbides, 2 nickel (Ni)/yttria-stabilized zirconia (YSZ), 1,3 cobalt/alumina, 4 and silver/ titania. 9,10 The method is simple and straightforward, yet often suffers from poor mixing uniformity of the dissimilar phases which may result in heterogeneous microstructure after sintering. One is from consolidation of powder mixtures by dry-pressing and sintering.…”

“…One is from consolidation of powder mixtures by dry-pressing and sintering. 9,10 The method is simple and straightforward, yet often suffers from poor mixing uniformity of the dissimilar phases which may result in heterogeneous microstructure after sintering. 11 On the other hand, cermets may be prepared by wet-processing route in which metal and ceramic particles are dispersed in liquids before being shaped into green compacts and are then fired at elevated temperatures.…”