激光熔覆高温自润滑覆层的裂纹成因与控制

Cause and Control of the Crack of Laser Clad High Temperature Self-lubricating Coatings

分析了激光熔覆高温自润滑覆层裂纹的形成原因,讨论了裂纹的影响因素及控制措施。结果表明:在覆层拉应力的作用下,柱晶间界及低熔点液态润滑相富集区域极易产生结晶裂纹。在保证覆层功能的前提下,优化复合粉末的组分,抑制柱状枝晶的长大;采取梯度复合覆层工艺及熔覆工艺参数优化,改变覆层的组织结构,提高覆层的韧性;同时采取措施调整覆层应力状态,降低热应力作用,可以有效控制覆层的裂纹倾向。

The formation mechanism of crack during the process of laser cladding high temperature self-lubricating coatings is analyzed. The factors that might influencing the appearance of the crack and some relevant countermeasures as well is discussed. The results show that the cracks formation influenced by tension stress has a tendency to the coating area with boundary column crystals or high content of low melting point lubricant phase. On the premise of keeping the functions of the coatings, the tendency of the appearance of crack in the coatings was effectively controlled by optimizing the constitution of the composite powders, inhibiting the growth of the dendrites, changing the microstructure and improving the toughness of the coatings with gradient compound cladding process and optimization of cladding parameters, as well as reducing the thermal stress.