防钛火隔热层抗开裂界面粗糙化设计制备研究

Roughening Design of Anti-Cracking Interface of Insulation Layer for Titanium-Fire Retardant Coating

钛合金在航空发动机中应用广泛,但它们在遇到剧烈冲击、摩擦等极端情况时易发生钛火,继而引起整台发动机着火,造成严重后果。在钛合金表面涂覆阻燃涂层是目前解决钛火问题的主要方法之一。然而,阻燃涂层是由陶瓷隔热层与金属基可磨耗面层组成的多层复合结构,在服役过程中,陶瓷/金属异质界面常发生剥落失效。基于此,主要开展陶瓷隔热层表面粗糙化设计,提升涂层抗开裂能力。首先,为确定喷涂工艺对粉末熔化程度的影响规律,采用模拟与试验相结合的方法,研究了空心与实心两种YSZ粉末粒子在等离子束流内的加热加速过程,明确了调控粉末熔化状态的控制参数,试验沉积单个扁平粒子验证了模拟结果的合理性。其次,开展了陶瓷隔热层表面形貌调控研究。基于模拟结果,确定隔热层主体应采用高功率,以保证粉末充分熔化;表面粗化层采用较低功率以获得半熔化态氧化锆球壳,从而制备得到表面具有较大粗糙度、内部具有良好隔热防钛火功能的新型隔热层结构。涂层表面的粗糙化设计,有利于提高金属陶瓷的异质界面结合强度,支撑涂层的长寿命防护。

Titanium alloys are widely used in aero-engines.Titanium fire will occur under extreme situations,such as intense impact and friction,consequently causing fire all over the whole engine.An effective way to avoid the accident is to coat fire-resistant coatings on titanium alloy.This fire-resistant coating consists of a ceramic thermal insulation layer and a metal-based abradable seal layer.However,cracking may occur at the interface between the ceramic layer and the metal layer during service.Given that,this study aimed to enhance the crack resistance based on surface roughening design of the ceramic layer.Firstly,the heating and speeding processes of hollow and solid yttria-stabilized zirconia(YSZ)powders in plasma beam was investigated by simulation and experiment,and the dominant parameters regulating powder melting state were obtained.The rationality of simulation results was verified by the deposition of individual splats.Furthermore,surface morphology of the ceramic thermal insulation layer was tailored.Based on the simulation results,the main part of the thermal insulation layer was prepared under a higher spraying power with fully melted powders.In contrast,the surface of the thermal insulation layer was deposited by a lower power with semi-molten powders.In this way,a thermal insulation layer can be prepared to both have high inside thermal insulation and large surface roughness.This is beneficial to improve the interface adhesion between the ceramic layer and the metal layer,which would support the long-life protection of coating.