Papers by Keyword: Aluminum Boride

Abstract: We sintered α (6H)- and β(3C)-SiC powders using an Al-B-C additive. SiC powders were densified to > 98% of the theoretical density from 1950 to 2150oC with 0.67-2.7 mass % AlB2 and 2.0 mass % C. Sintering temperatures are 150-200 oC lower than the conventional. During sintering, 6H polytype in α-SiC powder was partly transformed to 4H. α-SiC powder grew moderately into plate-shaped grains. β-/SiC powder was completely transformed to 6H and subsequently 4H with large grain growth. Low-temperature sintering enabled us to use hot isostatic pressing resulting in pore-free SiC materials.

Abstract: BN/Al(-Mg) metal matrix composite (MMC) was fabricated by the pressureless infiltration technique. The phase characterizations of the composites were analyzed using the SEM, TEM, EDS and EPMA on reaction products after the electrochemical dissolution of the matrix. It is confirmed that aluminum nitride (AlN) was formed by the reaction of Mg ₃N ₂ and Al alloy melt. Plate type AlN and polyhedral type Mg(-Al) boride were formed by the reaction between Mg ₂N ₂, BN and molten Al in the composite. The reaction mechanism in the fabrication of BN/Al(-Mg)MMC was derived from the phase analysis results and the thermodynamic investigation.