Hydrothermal silicon carbides

The discussion of hydrothermal diamond synthesis is divided into two sections, dealing with synthesis from C-H-0 liquids and synthesis based on decomposition of silicon carbide, respectively. Both start with thermodynamic calculations in order to demonstrate the theoretical possibility of carbon formation before the experimental findings are summarized. Naturally, equilibrium calculations do not consider kinetic limitations. 

HYDROTHERMAL OXIDATION OF SILICON CARBIDE AND ITS BEARING ON WET WEAR MECHANISMS... 

Hydrothermal Oxidation of Silicon Carbide and its Bearing on Wet Wear Mechanisms... 

Two of the most important key issues on the quest for a quantitative theory to predict wear rates of silicon carbide are the estimation of the true conditions (pressure, temperature, pH...) under ordinary wear conditions and the intrinsic behaviour of silicon carbide at severe hydrothermal conditions at higher temperatures. The study of the latter under static conditions is necessary to be able to build a wear theory for dynamic systems. Such questions are addressed in this paper. 

Presser, V., et al.. Tribological and hydrothermal behaviour of silicon carbide under water lubrication. Wear, submitted. 

B. Basavalingu, J. M. Calderon-Moreno K. Byrappa, Y. Gogotsi, and M. Yoshimura, Decomposition of silicon carbide in the presence of organic compounds under hydrothermal conditions. Carbon, 39, 1763-1767, 2001. 

Another possibility of carbon formation is the hydrothermal treatment of carbides (100 MPa, 300°C to 400°C in H2O). However, in this case athin, uniform carbon film is produced on the surface of the carbide. Recently, it was also shown that SiC can be transformed into nanocrystalline diamond during silicon etching with CI2 (by proper adjustment of the reaction parameters). It has not yet been tested if it also can be applied on the transition metal carbides. 

---