Analysis and Kinetics Modeling of the Isothermal Oxidation Behavior of Silicide Coatings

In this paper, an online apparatus was developed for isothermal thermogravimetric measurement of silicide coatings within a wide temperature range (from −180 °C to 2300 °C) based on thermogravimetric analysis. Firstly, the measuring principle and method regarding silicide coatings of this apparatus were studied. Secondly, on the basis of oxidation kinetics analysis, the intrinsic mechanism and kinetic parameters of three stages (oxidation, diffusion, and fall-off) of silicide coatings were studied, and the oxidation kinetics features were also analyzed. In addition, according to mathematical physics methods, a kinetics model of silicide coatings in different stages of oxidation was established, including parameters such as weight change, oxidation rate, oxidation time, etc. Finally, online isothermal experiments from −180 °C to 2300 °C werecarried out and analyzed. The results showed that the kinetic model established in this paper was in good agreement with the oxidation process of silicide coatings. In this paper, a complete kinetics model including different oxidation stages is proposed for the entire oxidation process of a silicide coating, revealing its oxidation mechanism. The research will play a significant role in the study of preparation technology improvement and high-temperature environment application. This paper studied two measuring methods: weight gain and weight loss measuring methods. Also, an experiment was carried out on the silicide coatings to explore the physical oxidation process between −180 °C and 2300 °C. The results proved the perfect consistency of the kinetics model proposed by this paper and the oxidation process of silicide coatings. This paper will play a significant role in the study of preparation technology enhancement and high-temperature environment application. It also provides a theoretical foundation for accelerated aging and life evaluation methods.