The boundary conditions for describing the mass transfer of carbon from a low-pressure oxygen-free atmosphere into steel under vacuum carburizing are analyzed. Experimental results and thermodynamic calculations are used to determine the numerical value of the activity of carbon in an environment of low-pressure acetylene. The calculated value of the carbon potential is used in the boundary condition of kind III in the form of a Langmuir expression applied to a mathematical model of vacuum carburizing based on numerical solution of the diffusion equation. The calculated concentration profiles are shown to describe adequately the experimental results. Different nonequilibrium processes of vacuum carburizing of steels are shown to have similarity.

分析了描述真空渗碳下碳从低压无氧气氛到钢中的传质的边界条件。实验结果和热力学计算用于确定低压乙炔环境中碳活性的数值。碳势的计算值以朗缪尔表达式的形式用于基于扩散方程的数值解的真空渗碳数学模型中的III类边界条件。计算出的浓度曲线足以描述实验结果。钢的真空渗碳的不同非平衡过程显示具有相似性。