Abstract: h-BN-SiO₂ ceramics were prepared by means of high pressure gas-solid self-propagating high temperature synthesis technology from powders of B, h-BN
and SiO₂. The nitrogen pressure and porosity of reactants that influence on ignition, and products have a scope, 48%≤ρ≤52%, 75MPa≤ρ≤85MPa, in which
the non-cracked combustion products can be obtained. The density of product is up to 1.79g·cm^-3 and the bending strength and hardness of h-BN-SiO₂ ceramic
are up to 76MPa and 212(HV) respectively. The higher the nitrogen pressure, the bigger the h-BN particles. The h-BN particles are isotropy. Crystalline B₇O and glasses
SiO₂ exist in the product. Crystalline SiO₂ was disappeared because of rapid cooling from combustion temperature to 1000℃. Glass’s phases that are not
found among the h-BN particles only exist at the edge of B₇O, which demonstrates that SiO₂ is the cause of B₇O formation.

Key words: h-BN-SiO₂ ceramics, self-propagating high temperature synthesis