Research on stability diagrams for BCl₃-C₃H₆-H₂ system

The stability thermodynamic diagrams for BCl₃-C₃H₆-H₂ system were calculated. The effects of reactant partial pressure, total pressure, and deposition temperature on product types and distribution regions of reacted solid products in the stable diagrams were discussed. The results are as follows: (1) the most important factor affecting deposit types and distribution regions of reacted solid products is total pressure. With the increase of total pressure, the stability diagram becomes complex; the region of elementary boron increases; the regions of B+B₄C and B₄C+C decrease; the region of B₄C shows no significant change; and the distribution regions of all deposits shift to the right side of the diagrams. (2) The element content in the deposits from the solid product reaction would be influenced by the reactant partial pressure. The compositions of deposits change from high boron contained to high carbon contained with the increase of C₃H₆ pressure, namely, from B or B+B₄C region to B₄C+C region. (3) The deposition temperature has no obvious influence within the temperature range of 800-1200°C, which indicates that the deposition process is not controlled by thermodynamic factors.