发动机气门机构材料技术及减摩抗磨研究进展OA

The valve mechanism is an important component of the engine,responsible for admitting air into the engine combustion chamber and expelling exhaust gases.With the continuous development of engine technology,the requirements for the performance of valve mechanisms are gradually increasing.The harsh working environment in the engine combustion chamber is an important reason for the decline in the service life of valve mechanisms.The wear of the valve mechanism is mainly reflected in the impact generated by the valve and the valve seat ring during operation,the damage of the valve spring during long-term and high-frequency operation and the wear caused by the fitting between the valve stem and the CAM.Therefore,the research on the anti-friction and anti-wear performance related to the engine valve mechanism is an important way to improve the overall working performance of the engine.The work aims to introduce the improvement of the tribological performance of the valve mechanism through new materials,new processes,new lubricating oil additives and surface modification technologies.The new materials refer to lightweight valves prepared mainly from TC4 aluminized titanium alloys.The treatment of titanium alloy samples by high-temperature oxidation,ion implantation,selective laser melting and other methods is also listed to improve the surface performance of the materials.Hollow sodium-filled valves represent a new type of valve manufacturing process.Hollow valves are prepared through methods such as die forging shrinkage cavities and extrusion and valve hammer forging and liquid sodium is added to achieve a cooling effect,thereby enhancing the surface performance of the valves.In the research of lubricating oil additives,commonly used engine oils include PAO,PAG,etc.,which plays a key role in improving the valve mechanism and the overall performance of the engine.During further research,nano-additives and bio-lubricants have been proven to be applicable as new lubricating oil additives to engines.In the research on traditional valve materials such as austenitic steel and martensitic steel,surface modification technology is an important way to improve the surface properties of materials.Commonly used surface modification technologies can be roughly divided into three categories.Physical surface modification technologies mainly include shot peening technology and laser surface micro-texture,while chemical surface modification technologies mainly include chemical heat treatment,electrochemical treatment,etc.Chemical-physical composite surface modification technologies can be classified into laser cladding and supersonic flame spraying.According to the application of different surface modification technologies,scholars in China and abroad have adopted methods such as friction and wear experiments,SEM scanning electron microscopy images and XRD patterns to reduce the wear during the working process and enhance the oxidation resistance of the material surface.There are various methods to enhance the wear resistance of material surfaces,such as reducing the friction coefficient of the material surface.The effects of different surface modification technologies on improving the surface properties of valve mechanisms and related materials are verified.Combined with the application of new materials and modification technologies by engine valve manufacturers at the valve level,the effects of different materials and surface modification technologies on improving the surface performance of valve mechanisms are summarized.Finally,the research on the anti-friction and anti-wear performance of engine valve mechanisms is prospected and suggestions are put forward.