液氧煤油发动机富氧燃气系统高温合金材料金属陶瓷涂层制备及防护机理

The design and preparation of a protective coating systems for oxygen-rich combustion flame conduit and copper-based nozzle with high bonding strength and high resistance of oxidation and ablation are the key issues for development of of high pressure chamber nozzle for liquid oxygen kerosene rocket engines. In this project two types of thermal spray nickel-based alloy coatings are strategically proposed, along with YSZ thermal barrier coating on the alloy coatings as the bond coat. Facing the common difficulty of low adhesive strength for thermal-sprayed alloy coatings on copper alloy and superalloy substrates, it is proposed to develop metallurgical self-bonding effect by creating ultra-high temperature droplets generated by plasma spraying using Mo-clad NiCrCu and Ni-Al based composite powders. The controlling factors influencing generation of ultra-high temperature droplet and bonding formation between alloy substrate and coatings will be investigated to clarify the bonding formation mechanisms. Then, a methodolgy to enhance adhesive strength of nickel based alloy coating will be developed through combining optimized spray conditions with post-spray annealing treatment. The effects of coating compositions, microstructure, and coating design on the resistance of high temperature oxidation and thermal cycling lifetime will be studied for Mo-NiCrCu/NiCrAlYX and NiAl based coatings to provide guidelines for design and deposition of high performance high temperature protective coating for both superalloy flame conduit and copper nozzle. Meanwhile, the evolution behaviors of Ni-based alloys and oxide coatings formed on Ni-based alloy surfaces under high temperature service conditions and their effect on possible spalling and subsequent failure mechanisms of coatings will be investigated. The thermal protection mechanism and failure behavior of the coating systems will be clarified. The achievements of this project should provide an important guidance for the design and fabrication of high performance and durable protective coatings for the liquid oxygen kerosene rocket engines.

针对液氧煤油发动机推力室铜合金喷管与高温富氧燃气导管对高结合强度与抗氧化及烧蚀防护涂层的迫切需求，本项目提出采用热喷涂制备两类具有低热导强氧化膜形成能力镍基合金涂层、并可与自生陶瓷氧化膜构成隔热涂层体系的热防护涂层设计；针对铜基喷管表面传统合金喷涂层与高温合金燃气导管表面涂层结合强度低的难题，提出通过Mo包覆NiCrCu与Ni-Al复合粉末设计、采用等离子喷涂获取超高温熔滴与碰撞自粘结效应的思路，研究超高温熔滴形成控制机制、影响熔滴与基体间结合形成的关键因素与结合形成机制，发展喷涂与热处理工艺结合显著提升合金涂层与合金结合强度、自生保护性氧化膜的制备方法；研究阐明NiCrCuMo/NiCrAlYX与NiAl基涂层成分、组织与性能、高温演变与氧化烧蚀的控制机制，发展热处理与氧化膜结构一体化控制工艺，为合金防护涂层制备提供依据；研究阐明合金涂层体系与自生氧化膜在高温服役条件的演变及其对涂层体系失效的控制因素与影响机制，为液氧煤油火箭发动机喷管等离子喷涂制备高性能长寿命防护涂层提供依据。

本项目针对液氧煤油火箭发动机高温富氧燃气高温合金导管与发动机推力室铜合金喷管对高结合强度与抗氧化及烧蚀防护涂层的迫切需求，提出采用热喷涂分别制备具有强氧化膜形成能力的抗高温氧化镍基合金涂层、具有与铜基体成分与性能匹配的高热稳定的低热导金属隔热涂层体系的热防护涂层设计与制备方法。. 针对控制涂层安全可靠应用的热喷涂金属合金涂层与基体界面结合和涂层内聚结合的关键问题，阐明了粒子自冶金连接的熔滴温度条件，发展了基于Mo包覆粉末结构设计、粒子尺寸效应与NiAl复合粉末放热反应协同提升温度的方法；发明了基于B与C合金复合化高温熔滴原位脱氧大气等离子喷涂制备低氧化物的涂层新方法。. 针对高温富氧燃气导管抗氧化保护涂层，提出了在高温合金表面等离子喷涂制备高结合强度NiAl基涂层与镍基合金涂层为主要保护涂层的方案；发明了基于复合金刚石引入碳源获得无氧化物金属熔滴喷涂制备低氧化物含量的致密NiAl抗氧化涂层制备方法，阐明了低氧含量NiAl涂层在高温大气氛中具有快速形成保护性氧化膜、并使其涂层粒子间界面发生自愈合强化的规律，通过涂层的高温高压氧气氛下氧化与富氧超音速焰流烧蚀行为揭示了大气等离子喷涂NiAl涂层对高温合金导管保护的可行性，为NiAl涂层用于高温高压富氧燃气管道抗氧化保护涂层提供了依据。. 针对推力室铜合金喷管热障涂层，发明了具有成分与热物理性能良好匹配的CuNi/NiCuCr/NiCrAlY多层结构金属热障涂层，发明了基于B合金化实现了低氧含量的Cu基CuNi涂层与镍基NiCuCr涂层粒子间结合充分的涂层制备方法，阐明了涂层合金成分与性能的关系及其在高温服役条件下涂层具有优越热稳定性的特征，揭示了涂层在高热流密度下热震试验失效行为并验证了CuNi/NiCuCr/NiCrAlY热障涂层体系具有优越抗热震性能的特征，为其用于推力室喷管热障涂层提供了试验依据。