某橡胶装置胶液搅拌器减速箱螺旋伞齿轮发生表面金属剥落失效，通过宏观检验、介质成分分析、材料成分分析、硬度测试、金相检验等方法对齿轮表面金属剥落的原因进行了分析。结果表明：润滑油水含量超标是造成该齿轮表面金属剥落的主要原因；水含量超标使润滑油黏度降低，齿轮间的摩擦力增大，齿轮运转过程中的接触疲劳应力促使凹坑形成，并造成金属剥落。针对金属剥落的原因对减速箱及齿轮的验收、维护提出了建议。

The surface metal peeling failure happened to the spiral bevel gear of a rubber plant glue agitator gearbox. The causes of surface metal peeling of the gear were analyzed by macroscopic inspection, medium composition analysis, material composition analysis, hardness test and metallographic examination. The results show that the excessive water content of lubricating oil was the main cause for the surface metal peeling of the gear. The excessive water content reduced the viscosity of the lubricating oil, and increased the friction force between the gears. Contact fatigue stress during gear operation caused the pit formation and metal peeling. Suggestions on acceptance and maintenance of gearboxes and gears were put forward for the metal peeling reasons.