活塞顶面热障涂层对活塞热负荷的影响

摘要

活塞顶面热障涂层可以有效降低活塞工作热负荷、提高活塞使用寿命.以一款非道路高压共轨柴油机铝合金活塞为研究对象,采用硬度塞测温法试验测试了无热障涂层活塞在最大转矩工况下表面19个特征点的温度值,同时采用等参法建立了活塞有限元仿真分析模型,对比分析了活塞顶面热障涂层对活塞温度场和热应力场的影响.研究结果表明:活塞顶面热障涂层能有效降低活塞头部和环槽区域的工作温度,活塞头部顶面区域温度下降幅度为20~32 ℃,一环和二环的环槽区域温度下降幅度为15~18℃;但活塞顶面采用热障涂层后,活塞基体顶面黏结层区域的热应力会急剧升高,活塞基体顶面、喉口区域以及边缘棱角处热应力集中现象明显,在活塞顶面喉口黏结层区域最大热应力达到291MPa,易导致热障涂层的剥落失效.%TBC at the top surfaces of pistons might reduce the thermal loads and improve the service life of pistons.A non road high pressure common rail diesel engine aluminum alloy piston was used as ob-ject of the study,the temperature of 19 feature points of the common piston was measured at maximum torque conditions with hardness plug,the finite element model of piston was established by isoparametric method.The influences of TBC of piston top on piston temperature field and thermal stress field were an-alyzed and compared.Results show that the piston top TBC may effectively reduce the working tempera-ture of piston head and ring groove region. The top surfaces of piston head in regional temperature de-crease 20~32℃,first ring and second ring groove’s temperatures decrease 15~18℃.However,the ther-mal stress on the top layer of piston matrix will increase sharply when TBC is applied to piston top,espe-cially the thermal stress concentration is obvious at the top of piston base,the throat area and the edge an-gle.The maximum thermal stress in the bonding zone of top throat of piston top reaches 291 MPa,which will lead to the spalling failure of TBCs.