热障涂层对DD6单晶燃气热腐蚀及力学性能的影响

Effect of TBCs on Gas Thermal Corrosion Resistance and Mechanical Properties of DD6 Single Crystal

DD6单晶高温合金材料以其优异的高温服役性能,在我国多型航空发动机制造领域拥有十分广阔的应用前景。随着我国航空发动机技术的不断发展,燃烧室涡轮前服役温度不断提升,DD6单晶高温合金无法完全满足高温、高压、高转速的服役环境,急需开展DD6单晶表面热障涂层技术研究。鉴于此,本工作采用多弧离子镀技术在DD6单晶高温合金上制备了NiCoCrAlY金属粘结层(BC),然后采用电子束物理气相沉积技术制备了Y_(2)O_(3)·ZrO_(2)(YSZ)陶瓷面层,研究热障涂层对DD6单晶抗燃气热腐蚀及力学性能的影响。结果表明:在900℃条件下,燃气热腐蚀性能测试100 h后,DD6合金表面形成了厚度约100μm的腐蚀疏松结构、孔洞及横向裂纹,DD6合金抗燃气热腐蚀性能较差;BC涂层或YSZ涂层内部未出现Na、K、Ca、Cl、S等腐蚀性元素,BC涂层表面形成了均匀连续的Al_(2)O_(3)层,在其表面粘附的Na_(2)SO_(4)未出现高温分解,腐蚀介质未对BC涂层产生侵蚀;YSZ涂层柱状晶组织具有较好的应变容限,高温时柱状晶膨胀引起柱晶间隙缩小,外部的腐蚀介质无法有效渗入YSZ涂层内部,从而避免了腐蚀介质对涂层或基体的侵蚀破坏。热障涂层对DD6单晶合金980℃条件下的抗拉强度σb、屈服强度σ0.2、延伸率δ和断面收缩率ψ无不良影响,断裂模式与未涂覆涂层试样一致,均呈典型的韧性断裂。在980℃、250 MPa条件下,涂覆与未涂覆涂层的DD6试样高温持久时间和延伸率δ无明显差异,呈典型的塑性变形和蠕变变形韧性断裂机制。本工作的研究结果为DD6单晶高温合金热障涂层技术的开发与工程化应用奠定了技术支撑。

DD6 single crystal high-temperature alloy material has a very broad application prospect in the field of multi type aviation engine manufacturing in China due to its excellent high-temperature service performance.With the continuous development of aviation engine technology in China,the service temperature of the combustion chamber turbine is constantly increasing.DD6 single crystal superalloy cannot fully meet the service environment of high temperature,high pressure,and high speed,and there is an urgent need to research DD6 single crystal surface thermal barrier coating technology.In view of this,this article uses multi arc ion plating technology to prepare NiCoCrAlY metal bonding layer on DD6 single crystal high-temperature alloy,and then uses electron beam physical vapor deposition technology to prepare Y_(2)O_(3)·ZrO_(2)ceramic surface layer,to study the effect of thermal barrier coating on the gas thermal corrosion resistance and mechanical properties of DD6 single crystal.The results indicate that,after 100 hours of gas hot corrosion performance testing at 900℃,a thickness of approximately 100μm corrosion porosity,pores,and transverse cracks was formed on the surface of DD6.There were no corrosive elements such as Na,K,Ca,Cl,S present inside the BC coating or YSZ coating.A uniform and continuous Al_(2)O_(3)layer was formed on the surface of the BC coating,and the Na_(2)SO_(4)adhered to its surface did not undergo high-temperature decomposition.The corrosive medium did not corrode the BC coating.The YSZ coating columnar crystals have good strain tolerance.At high temperatures,the expansion of columnar crystals leads to a reduction in the gap between columnar crystals,and external corrosion media cannot effectively penetrate into the interior of YSZ coating,thus avoiding corrosion damage to the coating or substrate caused by corrosion media.Tensile strength of thermal barrier coating on DD6 single crystal alloy at 980℃,there is no adverse effects onσb,σ0.2,δandψ,and the fracture mode of the sample is basically consistent.High temperature endurance time and elongation of DD6 single crystal sample coated with thermal barrier coating at 980℃,250 MPa,there is no significant difference,and the fracture has a typical dimple fracture morphology,with the fracture mechanism being a ductile fracture mechanism of plastic deformation and creep deformation.Based on the research results of this work,the technical support for the technical development and engineering application of DD6 single crystal super alloy TBCs is established.