Hexagonal boron nitride (h-BN) based ceramics have been fabricated by hot-pressing in a
nitrogen atmosphere at 1900°C for 60 min. under a pressure of 50 MPa with B2O3 as sintering
additive. The phase composition was confirmed by XRD. The microstructural properties of h-BN
powders and hot-pressed surfaces were evaluated by SEM-EDS analysis. The formation of the
secondary phase was also investigated with particular interest on grain boundaries. The sintered
densities were also determined by Archimedes’ method. The maximum relative density was
obtained to be about 92 %. The effect of the existence of boron oxide on the boron nitride grain
growth behaviour was discussed on the basis of microstructural features.
Spinel (MgAl2O4) ceramics possesses a high melting point, high hardness, a relatively low density, excellent transmittance, a high strength, a relatively low thermal expansion coecient, high thermal shock resistance and high chemical inertness. Aluminium titanate (Al2TiO5) exhibits extremely good thermal shock resistance and low thermal conductivity coupled with good chemical resistance in molten metals. In the present work, aluminium titanate/spinel ceramics composites with dierent percentages of Al2TiO5 were prepared using powder metallurgy techniques. The microstructural, mechanical and thermal properties were characterized using X-ray diraction, scanning electron microscopy, dierential scanning calorimetry, dilatometer and hardness. Thermal shock resistance behaviour under water quenching of the as-prepared ceramics was also evaluated. Results revealed that the addition of aluminium titanate to spinel matrix improves the properties of the aluminium titanate/spinel ceramics.
Porcelain represents one of the most complex ceramics, formulated from a mix of clay, feldspar and quartz, sintered at temperatures between 1200• C and 1400• C, to form a glass-ceramic composite. Aluminium titanate (Al2TiO5) exhibits extremely good thermal shock resistance and low thermal conductivity, coupled with good chemical resistance in molten metals. In the present work, aluminium titanate/porcelain ceramics composites with dierent percentages of Al2TiO5 was prepared using powder metallurgy techniques. The microstructural, mechanical and thermal properties were characterized using XRD, SEM, dilatometer and a hardness meter. Thermal shock resistance behaviour under water quenching of the as-prepared ceramics was also evaluated. The results have revealed that the addition of aluminium titanate to porcelain matrix improves the properties of the aluminium titanate/porcelain ceramics.
Yttria stabilized zirconia (YSZ, with 3 mol.% Y2O3) has superior high temperature properties such as high tolerance for thermal shock, low thermal conductivity, mechanical properties, elevated melting point, good phase stability, and excellent oxidation resistance. Aluminium titanate (Al2TiO5) exhibits extremely good thermal shock resistance and low thermal conductivity coupled with good chemical resistance in molten metals. In the present work, aluminium titanate/YSZ ceramics with dierent percentages of Al2TiO5 was prepared using powder metallurgy techniques. The microstructural, mechanical and thermal properties were characterized using X-ray diraction, scanning electron microscopy, dierential scanning calorimetry, dilatometer and hardness. Thermal shock resistance behaviour under water quenching of the as-prepared ceramics was also evaluated. The results revealed that the addition of aluminium titanate to YSZ matrix improves the properties of the aluminium titanate/ YSZ ceramics.
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