高温自蔓延合成复合涂层的研究现状

高温自蔓延合成技术因其节约能源、生产效率高、投资少、产品纯度高等特点,已用于制备特种性能陶瓷,是一种潜在的制备高性能涂层的方法 .介绍了由传统高温自蔓延合成技术延伸发展起来的自蔓延铸造涂层技术、自蔓延气相传输涂层技术、自蔓延烧结涂层技术和自蔓延反应喷涂涂层技术,重点分析了各种自蔓延合成涂层技术的基本原理、工艺特点、涂层特点、应用情况、研究现状及存在的主要问题.针对自蔓延合成涂层技术存在的问题,如孔隙率高(一般达5%~20%)、结合强度差(低于50 MPa)、反应速度快、过程难以控制等,提出了高温自蔓延合成复合涂层技术的研究方向:优化反应体系组分设计,设法避免低气化点反应生成相的形成,减轻自蔓延合成反应过程中的飞溅;加入添加剂延长液态停留时间和增强液相流动性;选择反应生成相与相之间以及生成相与基体金属都具有良好润湿性的反应体系;优化涂层结构设计,设计复合结构和梯度结构的涂层体系,提高涂层与金属基体的结合质量.

Research Progress in Composite Coatings Prepared by Self-propagating High Temperature Synthesis

Self-propagating high temperature synthesis (SHS) has many advantages, such as energy saving, high efficiency, low investment of production, and high product purity. It is one of the potential methods to fabricate high-performance ceramic/ metal composite coatings with some special properties. A series of self-propagating high temperature coating synthesis technologies have been developed based on the principle of SHS technology, such as self-propagating casting coating technology, self-propaga-ting gas-transmission coating technology, self-propagating sintered coating technology and self-propagating reactive thermal spraying coating technology. The basic principle, process features, coating characteristics, applications, research status and existing problems of the SHS coating technologies were introduced and reviewed. Focusing on the problems of SHS coating, such as high porosity (up to 5% to 20% ); low bonding strength ( <50 MPa), too fast reaction process, and difficult to be controlled, some research directions of SHS coating were proposed. The reaction system should be optimized to avoid the formation of the reacted product with low vaporization point and to reduce splashing during self-propagating synthesis process. Some additives could be used in the reaction system to extend the residence time of the liquid phase and to enhance liquidity of the reacted product. A good wettability between the reacted phases and phases, as well as coating and metal substrate is essential, and it must be considered seriously. In order to improve the binding quality of coating and metal substrate, composite coating and gradient coating should be employed by optimizing the coating structure design.