Si－C－O－N系统相稳定性和相稳定性图

对Ｓｉ－Ｃ－Ｏ－Ｎ系统进行了平衡状态下的相稳定性计算，绘制了在１４７３Ｋ和１５７３Ｋ下的Ｓｉ３Ｎ４、ＳｉＣ、Ｓｉ２Ｎ２Ｏ和ＳｉＯ２相稳定性与Ｎ２分压和Ｏ２分压的关系图以及Ｎ２分压和ＳｉＯ分区的关系图，Ｓｉ３Ｎ４／Ｓｉ２Ｎ２Ｏ／ＳｉＣ、ＳｉＯ２／Ｓｉ２Ｎ２Ｏ／ＳｉＣ两个三固相平衡点与Ｎ２分压、Ｏ２分压和ＳｉＯ分压以及温度的函数关系日。并以此确定Ｃ纤维－ＳｉＣ纤维转变和Ｃ纤维上涂层ＳｉＣ过程中，为获得稳定ＳｉＣ相的气体分压。

PHASE STABILITY AND PHASE STABILITY DIAGRAMSOF THE Si-C-O-N SYSTEM

The phase stability in equilibrium of the Si-C-O-N system was calculated. The phase stability diagrams for the Si3N4,SiC,Si2N2O and SiO2 at 1473K and 1573K were constructed as a function .of N2 and O2 partial pressures, and of N2 and SiO partial pressures. The diagrams which showthe changes in equilibrium N2,O2 and SiO partial pressures at invariant points (Si3 N 4 /Si2 N2 O /SiC andSiO2,/Si2N2O/SiC) as a fuction of temperatures were also given. From the phase stability calculationand phase stability diagrams, the Partial pressures of the gaseous phases can be defined, which areneeded to obtain a stable SiC phase in the processes of carbon fiber-SiC fiber conversion and coatingSiC on the carbon fibers.