中文摘要：

在一台使用M100纯甲醇燃料并提高压缩比的四缸点燃式发动机运行过程中，强制发生爆震。通过对爆震时燃烧过程的监测及破坏后的活塞宏观及微观结构进行的分析，提出纯甲醇点燃式发动机发生爆震破坏的活塞失效形式。研究中观察到纯甲醇发动机产生爆震时，发动机燃烧室内的爆发压力迅速升高，而且变化幅度剧烈，形成爆轰压力波。当该压力波作用在活塞上，使其表面及内部发生快速的热氧化腐蚀。金相分析表明，硅铝合金材质活塞的表面在爆轰波影响下，原始均匀分布的A1．si合金成分发生错位。通过扫描电子显微镜进一步分析，发现失效的活塞表面发生绝热剪切熔孔。再通过x射线衍射（X-raydiffraction，XRD）成分确定后，观察到失效活塞表面的晶型有了改变。根据获得的缸内燃烧情况，得出纯甲醇发动机发生爆震时的压力波破坏形式。对照爆震发生时发动机燃烧室内的缸压变化，提出一种爆震压力波对活塞表面的影响模式。

英文摘要：

Knock occurrs in a spark ignition engine with four-cylinder and high compression ratio, resulted in deliberately piston damage of the engine while burning methanol（M100）.Through monitoring pressure trace in cylinder and analyzing damaged part of piston from its surface and micro-structure inside body, the mode of piston damage and＇ failure under stronger knocking combustion is proposed. The results observed show that the outbreak of pressure in combustion chamber varies acutely and then forms the detonation wave while strong knocking combustion occurrs. When the wave acts on surface, it would transmit its action and then cause quick oxidation corrosion inside of piston body. Metallographic analysis shows that the surficial material of the piston with silicon/aluminum alloy is distorted from the original uniform distribution of the alloy component under attack of detonation wave. Through further using scanning electron microscopy（SEM）, surface piston damage occurred adiabatic shearing melt hole. Meanwhile, through the composition determined by X-ray diffraction（XRD）, the surface crystal of the piston failed has changed. Based on pressure variation in cylinder and analysis of material, a piston destruction mode of engine with methanol as fuel is concluded.