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Xiaoyu Shi, Chongxiao Guo, Jiamiao Ni, Songsong Yao, Liqiang Wang, Yue Liu, and Tongxiang Fan, Growth kinetics of titanium carbide coating by molten salt synthesis process on graphite sheet surface, Int. J. Miner. Metall. Mater., 31(2024), No. 8, pp.1858-1864. https://dx.doi.org/10.1007/s12613-023-2749-8
Xiaoyu Shi, Chongxiao Guo, Jiamiao Ni, Songsong Yao, Liqiang Wang, Yue Liu, and Tongxiang Fan, Growth kinetics of titanium carbide coating by molten salt synthesis process on graphite sheet surface, Int. J. Miner. Metall. Mater., 31(2024), No. 8, pp.1858-1864. https://dx.doi.org/10.1007/s12613-023-2749-8
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石墨片表面熔盐合成TiC涂层的生长动力学

摘要: 碳纤维,石墨等碳基材料具有密度小且在高温下仍具有高机械强度的特点,因而在极端环境和超高温部件中得到广泛应用。然而,碳基材料在极端服役条件下的抗氧化性能较差,通常需要进行表面防护。其中,难熔碳化物因具有极高熔点且与碳基材料化学适配度高等特点而广泛作为碳基材料的表面改性涂层。本文采用熔盐合成(MSS)法在石墨基体表面制备碳化钛(TiC)涂层,研究了熔盐合成过程中的反应动力学。扫描电镜表征(SEM)、X射线衍射(XRD)与理论分析结果表明,TiC涂层的生长动力学由碳(C)在TiC涂层中的扩散速度决定。与此同时,钛粉(Ti)通过液相传质参与反应,且其扩散距离及含量会影响TiC两侧的C浓度梯度进而影响反应速率。此外,通过分析TiC涂层厚度与热处理时间和温度的关系,发现TiC厚度与热处理时间呈抛物线关系,且在700–1300°C的范围内熔盐反应的活化能约为179283 J·mol−1。在此基础上,本文结合扩散动力学模型提出了石墨表面熔盐生长碳化物的动力学方程。上述结果为理解MSS过程中碳化物涂层的生长机制及其可控制备提供了理论依据。

 

Growth kinetics of titanium carbide coating by molten salt synthesis process on graphite sheet surface

Abstract: The synthesis of carbide coatings on graphite substrates using molten salt synthesis (MSS), has garnered significant interest due to its cost-effective nature. This study investigates the reaction process and growth kinetics involved in MSS, shedding light on key aspects of the process. The involvement of Ti powder through liquid-phase mass transfer is revealed, where the diffusion distance and quantity of Ti powder play a crucial role in determining the reaction rate by influencing the C content gradient on both sides of the carbide. Furthermore, the growth kinetics of the carbide coating are predominantly governed by the diffusion behavior of C within the carbide layer, rather than the chemical reaction rate. To analyze the kinetics, the thickness of the carbide layer is measured with respect to heat treatment time and temperature, unveiling a parabolic relationship within the temperature range of 700–1300°C. The estimated activation energy for the reaction is determined to be 179283 J·mol−1. These findings offer valuable insights into the synthesis of carbide coatings via MSS, facilitating their optimization and enhancing our understanding of their growth mechanisms and properties for various applications.

 

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