硅溶胶包裹碳化硅粉体氧化动力学的研究

Study on Oxidation Kinetics of Silica Solution Coated SiC Powders

采用硅溶胶对碳化硅(SiC)粉体进行包裹,以改善SiC的抗氧化能力,延长其作为窑炉内壁涂层材料的使用寿命,一方面在保持其高辐射率前提下,提升抗氧化能力,另一方面研究了硅溶胶包裹前和包裹后,这两种粉体的氧化动力学过程,为后续相关研究和工业化应用提供参考。研究发现,包裹后的红外透过率比包裹前的低。对这两种粉体在不同温度进行了循环氧化实验,发现包裹后SiC的抗氧化性能明显提高,且在高温下作用更为显著,经过1300℃、36 h的循环氧化后,单个硅溶胶包裹的SiC颗粒单位表面积的增重为3.17 g/m^(2),而纯SiC颗粒的增重则高达4.61 g/m^(2)。依据实验数据,通过模型拟合建立了包裹前和包裹后SiC粉的氧化动力学方程。利用Arrhenius方程探讨了两种粉体氧化反应速率常数K与氧化温度T的关系,发现硅溶胶包裹SiC的氧化活化能(44366.8296 J/mol)比未包裹的SiC活化能(36321.3718 J/mol)高。

Silica solution was adopted to coat silicon carbide(SiC)to improve its oxidation resistance and extend its service life as a coating material for the inner wall of the kiln.On the one hand,the oxidation resistance was improved under the premise of maintaining the high infrared emissivity.On the other hand,the oxidation kinetics processes of the SiC before and after silica solution coating were studied to provide a reference for the subsequent related research and industrial application.The results found that infrared transmittance was lower than before.Cycling oxidation experiments were conducted on the two powders at different temperatures,revealing a significant improvement in the oxidation resistance of SiC coated,especially at high temperatures.After cyclic oxidation at 1300℃for 36 h,the weight gain per unit surface area of SiC particles coated by silica solution is 3.17 g/m^(2),while pure SiC powders are up to 4.61 g/m^(2).Based on the experimental data,the oxidation kinetics equations for SiC powder before and after coating were established through model fitting.The relationship between the oxidation reaction rate constant K and the oxidation temperature T was explored using the Arrhenius equation,showing that the activation energy for oxidation of silica solution coated SiC(44366.8296 J/mol)was higher than that of SiC without coating(36321.3718 J/mol).