Surface chemistry of BORAZON: I, Analysis of the three cubic boron nitride materials: Type 1, 510, and 550.

摘要

Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were used to characterize the surface chemistry of three BORAZON* materials: Type I, 510, and 550. Samples were examined in the ''as-received'' condition and following heat treatments in air. Boron oxides were found on the Type I and 550 BORAZON crystals; oxide thicknesses were estimated to be 15A. The titanium-coated product, 510, was found to have a discontinuous titanium coating with a TiO(sub 2) layer that was approximately 20A thick. Following heat treatment at 800(degrees)C for 1 hr in air, the boron oxide layer on the Type I crystals was found to increase in thickness to approximately 30A. The same heat treatment on the 510 crystals yielded a multi-layered structure consisting of an enriched outer layer of B(sub 2)O(sub 3) over a predominantly TiO(sub 2) one. The entire initial titanium coating was oxidized, and segregated patches of B(sub 2)O(sub 3) (''islands'') were observed. The segregated patches can be explained in terms of the coalescence of liquid B(sub 2)O(sub 3) (melting point = 450(degrees)C). The 550 crystals were oxidized at 500(degrees)C. The oxide formed at this temperature was B(sub x)O (x > 0.67). These results were interpreted in terms of their potential use in sealing BORAZON to glass in vitreous bonding.