CHEMICAL VAPOR-DEPOSITION OF HEXAGONAL BORON-NITRIDE THICK-FILM ON IRON

A crystalline and semicrystalline hexagonal BN thick film was obtained on carbon steel (0.3% C) substrate by CVD from the reactant system, BCl3-NH3-H2-Ar. A translucent and crystalline BN film of about 100 μm thick was formed for the reaction time of 90 min in the temperature range of 1100 to 1200°C, while an opaque and semicrystalline BN film was grown at temperatures below 1100°C. The moderate feed gas flow rates were as follows: BCl3 : 0.1 - 0.2 ml/sec; NH3 : 0.8 - 1.2 ml/sec; H2 : 0.5 - 1.0 ml/sec; Ar: 0.5 ml/sec. The deposited film has a conical structure with some large nodular deposits, which suggests that the formation of the first BN layer is initiated by a catalytic action of iron. © 1979.