FORMATION OF NOVEL CARBON BY CONTROLLED OXIDATION CARBIDES AND DEVELOPMENT TO FABRICATION OF CARBIDE/CARBIDE COMPOSITES

点击翻译按钮获取中文摘要

A ZrC single crystal was oxidized isothermally at temperatures of 600 to 150 0C in a mixed atmosphere of oxygen and argon with an oxygen partial pressure(Po_2) of 0.02 to 2 kPa for 1 to 20h.The ZrO_2 scale was shown to consist of two subscales, zones 1 and 2. Interfacial area in zone 1 was composed of regular lattice fringes corresponding to the 111,200 and 220 lattices of cubic ZrO_2 (c-ZrO_2) crystallites of 2 to 10 nm in size and amorphous phase. The growth of crystallites occurred in zone 2, which visualized the interface of the zones 1 and 2.Black thin films reminicent of zone 1 were successfully separated, which were composed of amorphous carbon in which c-ZrOX_n particles of 20 nm in size were included. Two subscales could be separated as oxide plates and carbon films, respectively, from the oxidized ZrC by treatment with a concentrated HF solution. The films obtained at low temperatures (700 to 1100ﾟC) were amorphous, as evidenced by TEM observation and Raman spectra.The hexagonal planes of carbon in the films tended to grow ; on the electron diffraction pattern, halos changed to arcs or rings at 1500ﾟC.The t-ZrO_2 particles, several to tens of nano-meters in size, were dispersed in the carbon films.