Gaseous Corrosion of Ceramics

9870265准备好本项目的目标是对陶瓷的活性气体腐蚀有一个基本的了解。本研究将研究含卤素气体，首先是氯化氢(HCl)对陶瓷的高温腐蚀。关于陶瓷的活性气态腐蚀的数据很少，也就是说，反应产物通常是气态的腐蚀。然而，那些确实存在的数据表明，产物气体的气体扩散控制着高温下的反应速度。因此，可以根据热力学数据和气体动力学理论来预测腐蚀速度。氯化氢将被用作初始反应气体，因为与其反应产生的平衡产物气体压力在很大的温度范围内将是高的，因此应该可以观察到从扩散控制的动力学到表面反应控制的动力学的转变。一旦定义了表面反应是速率控制的参数空间，就可以研究表面反应的机理。在反应动力学之后，将测量失重和晶界沟槽作为温度和气体组成的函数。将研究单组分和多组分的氧化物、氮化物和碳化物。这项研究的意义在于，陶瓷的卤素腐蚀在化学加工、焚烧炉、化学废物处理、半导体加工和高温热机中具有重要的技术意义。了解动力学可以帮助材料工程师设计出不太容易被这些气体降解的材料。***

9870265 Readey The goal of the project is to gain a fundamental understanding of the active gas corrosion of ceramics. This research will study the high temperature corrosion of ceramics by halogen-containing gases, initially hydrogen chloride (HCl). There exist very few data on active gaseous corrosion of ceramics; that is, corrosion in which the products of the reaction are generally gaseous. However, those data that do exist show that gas diffusion of the product gases controls the rate of reaction at high temperature. As a result, the rate of corrosion can be predicted from thermodynamic data and the kinetic theory of gases. Hydrogen chloride will be used as the initial reactant gas since the equilibrium product gas pressures produced in reactions with it are predicted to be high over a large temperature range, and thus it should be possible to observe the transition from diffusion-controlled kinetics to surface reaction-controlled kinetics. Once the parameter space where a surface reaction is rate controlling is defined, then the mechanisms of the surface reaction can be studied. The reaction kinetics will be followed by weight loss measurements and grain boundary grooving as a function of temperature and gas composition. Single and multicomponent oxides, nitrides, and carbides will be studied. %%% The significance of the research is that halogen corrosion of ceramics has important technical implications in chemical processing, incinerators, chemical waste disposal, semiconductor processing, and high temperature heat engines. Understanding the kinetics can help materials engineers design materials that are less subject to degradation by these gases. ***