基于开口火药气体冲刷试验钛合金/Ta-W涂层体系烧蚀、冲刷行为研究

The development of aerospace engines with high thrust to weight ratio and the lightweight of weaponry, parts and automobiles stimulate the extensive using of high specific strength titanium alloys in these areas. But the poor ablation-resistance of titanium alloys severely limit its applications in the ablation atmosphere of high temperature, high pressure and high velocity. In this project, ablation-resistance Ta-W coating will be fabricated on titanium alloys using arc ion plating (Multi-target rotary plating). The preparation parameters of arc ion plated Ta-W coating on titanium alloys is opetimized. The microstructure and the alloy/coating interface are characterized. Based on the vented combustor tests. the distribution of temperature, pressure and velocity in the samples is obtained. The effects of temperature, pressure and velocity on the ablation speed is studied. The ablation behavior of titanium alloy/Ta-W coating system is studied, including the melting, metallurgical transformation, elements diffusion, interfacial reactions, gas-solid chemical reaction and the failure of thermal shock. The thermal-chemical-mechanical ablation model of titanium alloy/Ta-W coating system is presented based on the research above. The results are meaningful to the fabrication of refractory metal base coatings, the design and effect evaluate of ablation-resistance coating materials and the engineering application of titanium alloys.

随着航空航天发动机推重比的不断提高、零部件减重、武器装备轻量化、汽车减重等应用需求的出现，高比强度钛合金在上述领域的应用越来越广泛。钛合金不耐烧蚀和冲刷特性极大地限制了其在高温、高压、高速、烧蚀、冲刷性气氛中的应用。本项拟目利用电弧离子镀方法（多靶转镀）在钛合金表面制备耐烧蚀、冲刷Ta-W涂层。研究优化钛合金表面电弧离子镀Ta-W参数，表征涂层组织结构及界面状态；基于开口火药气体冲刷试验，研究获得试样烧蚀温度、气体压力、气流速度分布规律及其对烧蚀速率的影响；研究钛合金/Ta-W涂层体系烧蚀、冲刷行为（熔化、元素扩散、界面反应、固-气化学反应、热震剪切破坏行为）；初步构建钛合金/Ta-W涂层体系热-化学-机械烧蚀、冲刷模型。为难熔金属基涂层的制备、耐烧蚀涂层材料体系的设计、效果评估及钛合金的工程应用提供重要理论基础和实践指导。

钛合金在高推动比航空航天发动机关键零部件减重、武器装备轻量化、载运工具减重等国民经济重要领域的应用需求广泛，但钛合金不耐烧蚀和冲刷特性极大地限制了其在高温、高压、高速、烧蚀、冲刷性气氛中的应用。本项目利用电弧离子镀（多靶转镀）在钛合金表面制备耐烧蚀、冲刷Ta-W涂层，进一步表征涂层组织结构及界面状态，采用开口火药气体冲刷试验、脉冲激光加热试验、有限元数值模拟等方法进一步研究钛合金/Ta-W涂层体系烧蚀、冲刷行为，初步构体系热-化学-机械烧蚀、冲刷模型。. 采用电弧离子镀多靶转镀在钛合金表面制备了高α-Ta含量Ta-(10 wt.％)W涂层，进一步优化了钛合金表面电弧离子镀Ta-W涂层参数，为工程应用打下基础；钛合金 中β-Ti与α-Ta (W) 晶体结构和晶格参数相似，涂层与基体界面保持共格关系，沉积过程β-Ti可促进α-Ta (W)的形成，利于涂层性能的改善；纯热暴露过程中，涂层有效厚度保持稳定，无明显变化、涂层/基体体系界面及元素稳定性优异、涂层相组成（多晶 α-Ta(W) ）及尺寸(沉积态 46 nm750 ℃, 49 nm950 ℃ 51 nm)均无明显变化相稳定性优异、但钛合金基体同素异晶转变温度对体系界面和元素稳定性影响明显；侵蚀性气氛高温热震过程中，高熔点高热导率Ta-W涂层吸收并富集热量，对钛合金基体有明显的热障保护作用、随着热震次数的增加，Ta-W涂层颗粒尺寸逐渐变小并散布于熔化层，导致涂层元素富集于此而持续保护基体、涂层不同区域大温差形成的循环热应力，热熔化形成的孔洞（带）等缺陷加速涂层裂纹扩展和失效是其高温热震过程失效的主因。Ta-W涂层/钛合金体系烧蚀失效模型可初步归纳为热熔化叠加热机械应力引起并加速涂层裂纹扩展，热作用下高侵蚀性气氛沿裂纹加剧其侵蚀性的协同作用。