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本文主要研究在O_2/N_2混合气氛下,三氯乙烯(TCE)热氧化的动力学向题。研究中,采用最小二乘法,将五种函数(包括三种线性回归方程、对数和反对数)对实验数据进行计算机拟合分析,找出TCE氧化生长中氧化层厚度随氧化时间变化所遵循的规律,给出氧化层厚度随氧化时间变化,氧化速率随氧化层厚度变化的曲线,■及氧化速率常数随氧分压变化的计算结果,并就有关向题进行分析。研究结果表明:在氧分压Po_2=0.95atm,温度T=850°～1050℃,以及Po_2=10~(-2)～10~(-1)atm,T=1050℃的条件下,TCE氧化遵循线性一抛物线规律。在Po_2=5×10~(-2)～10~(-1)atm,T=850℃的条件下,TCE氧化遵循抛物线规律,TCE氧化的速率不仅大于普通干氧氧化,而且氧化速率dx/dt随氧化层厚度x的变化率与TCE的相对含量有关。随着TCE含量的减少,氧化速率的变化率趋于增大。与普通干氧氧化相似,TCE氧化的速率常数随氧分压的增大而增大。本文引入TCE氧化的有效扩散系数Deff(它大于普通干氧化的扩散系数D,且受TCE氧化与普通干氧氧化含量的调制)的概念,用于初步解释TCE生长规律的区别。
In this paper, the kinetics of thermal oxidation of trichlorethylene (TCE) under O 2 / N 2 mixed atmosphere was studied. In the study, the least square method was used to fit the experimental data with five functions (including three kinds of linear regression equations, logarithm and anti-logarithm) to find out the change of the oxide layer thickness with oxidation time in the TCE oxidation growth The relationship between the oxide thickness and the oxidation rate as a function of the oxide thickness and the change of the oxidation rate constant with the partial pressure of oxygen are given. The related problems are also analyzed. The results show that under the condition of the partial pressure of oxygen (Po_2 = 0.95atm, temperature T = 850 ° ~ 1050 ℃, Po_2 = 10 ~ (-2) ~ 10 ~ (-1) atm and T = 1050 ℃) Follow a linear parabolic law. Under the condition of Po_2 = 5 × 10 -2 ~ 10 -1 atm and T = 850 ℃, the oxidation of TCE follows the parabolic law. The rate of TCE oxidation is not only higher than that of ordinary dry oxygen oxidation, but also the oxidation rate dx / The rate of change of dt with the thickness x of the oxide layer is related to the relative content of TCE. As the TCE content decreases, the rate of change of the oxidation rate tends to increase. Similar to ordinary dry oxygen oxidation, the rate constant of TCE oxidation increases with the increase of oxygen partial pressure. In this paper, the concept of effective diffusion coefficient Deff of TCE oxidation (which is larger than diffusion coefficient D of ordinary dry oxidation and controlled by TCE oxidation and ordinary dry oxygen oxidation) is introduced to explain the difference of TCE growth rules.