【作者】 刘春晓；

【导师】 肖金生；

【作者基本信息】 武汉理工大学 ， 轮机工程， 2003， 硕士

【摘要】 随着生态环境的日益恶化和环境资源的日渐短缺，人们对环境保护和节约能源越来越重视。各国为限制内燃机排放所制定的法规更加严格，各大内燃机制造厂家在内燃机节能技术方面的竞争也愈演愈烈。因此，尽可能地降低油耗和减少有害排放就成为内燃机的发展目标。本文引入功能梯度材料(FGM)的概念，结合燃油掺水乳化燃烧技术，运用催化燃烧技术，在内燃机燃烧室部件内表面(活塞顶面、缸盖和气阀底面)先喷涂陶瓷/金属热障功能梯度涂层(TBC)，再喷涂催化剂/陶瓷催化功能梯度涂层(EBC)，以形成催化/热障功能梯度涂层(TBC-EBC)，使喷入的燃油和水蒸气在相对较低的温度下(200～500℃)发生重整催化反应，生成少量的氢气，从而改善燃油的燃烧过程，同时提高内燃机的环保性能、经济性能和隔热性能。这是一个全新的研究方向。 本文结合2001年度武汉理工大学材料复合新技术国家重点实验室开放基金项目“环保型梯度热障涂层的设计方法与制备工艺的研究”，对催化/热障功能梯度涂层中传热和热应力分布进行了理论分析与数值计算。同时，建立了催化/热障功能梯度涂层的水蒸气重整催化性能数学模型。最后，对催化/热障功能梯度涂层的制备工艺和性能评价进行了初步的实验研究。 文中首先阐述了催化/热障功能梯度涂层的材料结构模型和物性模型，然后根据热传导理论和热弹性理论，建立了用于催化/热障功能梯度涂层中传热和热应力分析的多层平板模型和多层圆筒模型，它们都是由金属基体层、过渡金属层、陶瓷/金属热障功能梯度层和催化剂/陶瓷催化功能梯度层四层组成，其中梯度层的梯度结构分别采用多项式和幂函数两种分布函数。通过具体的计算实例，采用解析解和有限元解对催化/热障功能梯度涂层多层平板模型和多层圆筒模型的温度场和热应力场进行了分析计算。经计算对比，发现两者能够很好地吻合。 为了分析催化/热障功能梯度涂层对内燃机的节能和降低排放的影响，根据化学反应动力学理论和多相催化理论，建立了甲烷水蒸气重整催化反应的化学反应速度数学模型，将内燃机中催化/热障功能梯度涂层的水蒸气重整催化反应分为预催化方式和表面催化方式，并从这两个方面来分析了甲烷水蒸气重整催化反应作用下的着火燃烧化学反应方程式。进一步，根据脂肪烃和芳烃的水蒸 武汉理工大学硕士学位论文气重整催化反应实验数据，建立了轻油水蒸气重整催化反应的化学反应速度数学模型，可以获得氢气的生成速度或量。这对于研究燃油水蒸气重整催化反应对内燃机燃烧过程的影响是很有意义的。 根据催化/热障功能梯度涂层的结构和性能要求，使用等离子喷涂技术，并对涂层的制备工艺参数进行了优化，制备了催化/热障功能梯度涂层试样和可用于实机实验催化/热障功能梯度涂层。借助扫描电子显微镜和X射线能谱分析仪，对所制作的涂层试样进行了金相显微分析和成份分析，并对涂层的催化效果进行了初步的评价。从试验获得的数据表明，本文所制备的催化/热障功能梯度涂层中催化涂层的表面上有催化剂的烧结颗粒，这将必然影响到涂层的重整催化作用效果。因此，文中提出了对等离子喷涂设备的改进措施和涂层喷涂后的后处理措施。这为催俗热障功能梯度涂层的成功制备打下了良好的基础。更多还原

【Abstract】 With the deterioration of ecological environment and the shortage of environmental resource, human beings pay more attention to the environmental protection and energy conservation. The rule of law established for emission of internal combustion engine (ICE) is stricter; the competition of energy-saving technology among ICE plants is more violent. Therefore, energy-saving and emission decrease are the development objects of ICE. Introducing into Functionally Gradient Materials (FGM), integrating the emulsive combustion technology with the catalytic combustion technology, Ceramic/Metal Gradient Thermal Barrier Coatings (TBC) and Catalyst/Ceramic Gradient Environmental Barrier Coatings (EEC) are sequentially sprayed on the inside surface of chamber components of ICE to form Catalysis/Thermal Barrier Functionally Gradient Coatings (TBC-EBC), which can result in reforming catalysis reaction between fuel and steam under relative low temperature (200-500℃) to produce a small quantity of hydrogen gas and improve the combustion process of fuel as well as the emission - behavior, economic performance and the reliability of ICE. This is a new research direction."Conjoining the project of "Research on Design Methods and Manufacture Techniques for Gradient Thermal Barrier Coatings with Environment Protection Function" funded by the Open Foundation from the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, this paper carried out theoretical analysis and numerical calculation of heat transfer and thermal stress in TBC-EBC. The mathematical model of the steam reforming catalysis reaction on TBC-EBC is established. And, the manufacture techniques and performance evaluation of TBC-EBC are also carried out in experiments.The structure model and the physical property model of TBC-EBC are set forth. In terms of heat transfer theory and thermoelastic theory, multi-layer plate model and multi-layer cylinder model are established for heat transfer and thermal stress analysis in TBC-EBC. They are both composed of four layers, i.e. substrate layer, bond layer,gradient TBC layer and gradient EBC layer, of which the gradient structure of gradient TBC layer and gradient EBC layer adopt polynomial and exponential function model. As for concrete calculation example, the temperature field and the thermal stress field in TBC-EBC are analyzed by analytical solution and the finite element method. The results show that the analytical solution shows good agreement with finite element solution.In order to study the influence from TBC-EBC on energy-saving and emission behavior of ICE, the chemical reaction speed model of reforming catalysis reaction between methane and steam is established in terms of chemical reaction dynamics and multi-phase catalysis theory. The ignition chemical equations of methane/steam reforming catalysis reaction in the pre-catalysis reforming reaction and the surface catalytic reforming reaction are studied. Furthermore, on the basis of experimental data from the steam reforming reaction with aliphatic hydrocarbon and aromatic hydrocarbon, the chemical reaction speed model of reforming catalysis reaction between fuel and steam is established, through which the quantity of hydrogen gas can be obtained. It is very meaningful for the study of the steam reforming reaction’ s influence on the combustion process in ICE.According to the structure and performance requirement, TBC-EBC samples and real TBC-EBCs for ICE have been fabricated by plasma spray technique. The samples are observed by scanning electron microscopy (SEM), the components in them are analyzed by X-ray spectroscopy (XRS). And, the catalytic effect of TBC-EBC is appraised. The experiment shows that the sintered catalyst particles were found on the surface of TBC-EBC samples, which will affect the catalysis performance of TBC-EBC. As a result, the modified measures and the post treatment are put forward in order to provide foundation for the successful fabrication of TBC-EBC.更多还原