水冷壁管梯度陶瓷涂层的设计与性能研究

针对燃煤电厂锅炉水冷壁爆管问题,研究设计了一种热膨胀系数梯度变化的涂层结构.为了提高涂层与基体的结合强度,计算了涂层及管壁的温度场及热应力场的分布.结果表明:涂层与管壁的界面处热应力最大,并且热应力与涂层的热膨胀系数成正比,通过调整涂料各成分的含量来改变各层的热膨胀系数;采用双层结构梯度涂层,理论计算表明界面处的最大热应力为1.78 MPa;而通过拉伸力学性能测试得出涂层的平均抗剪切强度为5.60 MPa,是界面处最大热应力值的3倍左右.因此,在管壁表面喷涂功能梯度涂层,能够缓和涂层与基体界面间的热应力.

Design and properties of graded ceramic coatings on water-wall tubes

A ceramic coating structure is designed of which the thermal expansion coefficient (TEC) is changing across the graded coating to solve the problem of breakage for water-wall tubes of coal-fired power plant.To improve shear strength between coating and substrate,the distribution of temperature and stress fields of coating and tubes were calculated.The results showed that the maximum of thermal stress was 1.78MPa at the interface between coating and substrate.Furthermore,the thermal stress was proportion to the TEC.So two layers graded coating structure was designed by adjusting the content of every component to change TEC.However,tensile test showed that the shear strength of coating was 5.6MPa,about three times of the maximum thermal stress of the interface.So the graded ceramic coating with TEC changing can efficiently relax thermal stress of interface between coating and substrate.