Formation of ZrB2-AlN mixed powder by self-propagating high-temperature synthesis (SHS) was investigated. Powders of Zr, B, BN and Al (purity >99 %) was used as the starting materials. Two initial mixtures were prepared and mixed at specific ratios. The first mixture was made of Zr and B, which were weighed at stoichiometric amounts to form ZrB2. The second mixture contained Zr, BN and Al; amounts of which were calculated so as to form ZrB2 and AlN.
The starting powders were mixed in a mortar and pestle, and then the reactant mixture was slightly pressed in a steel die. The SHS reactions were conducted in high purity argon atmosphere, in an SHS chamber. The reactant pellet was ignited from one end with a tungsten wire. The reaction products were examined with scanning electron microscopy and they were subjected to X-ray diffraction analyses.
It was found that when the reactants contained 40 % mixture-1 and 60 % mixture-2, according to the XRD results of the products, the peaks related to ZrB2 were dominant. The product contained some AlN and ZrN. When the amount of mixture-2 was increased to 90 %, the amounts of AlN and ZrN both were observed to increase. When Al amount in mixture-2 was increased by 30 % and mixture-2 was added as 90% into mixture-1, amount of AlN in the reaction products increased and amount of ZrN decreased. According to SEM examinations, ZrB2 particles were seen to be mixed with AlN particles in the reaction products. Size of ZrB2 particles were about 1 micron and AlN particles were larger.
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