气氛保护等离子喷涂成形W/Re合金喷管的抗热震烧蚀性能研究

用包覆法制备W-5%Re复合喷涂粉末, 再采用气氛保护等离子喷涂成形技术结合真空烧结技术制备内径为8 mm、壁厚16.5 mm、长30 mm的某实验型固体火箭发动机W/Re复合喷管, 并测试了喷管在地面点火试车条件下的抗热震烧蚀性能。研究结果表明, 气氛保护等离子喷涂成形W/Re喷管为典型的柱状晶层片结构, 致密度仅为87.5%。经2 300 ℃真空烧结480 min后, W/Re合金喷管由层片结构转化为颗粒状结构, 致密度提高至98.6%, 综合力学性能显著提高。地面试车实验后, W/Re合金喷管整体结构完好, 未出现炸裂和破碎现象, 抗冲刷和耐烧蚀性能良好, 其线烧蚀率仅为0.15 mm/20 s。经SEM、EDS等检测发现, 喉部以机械剥蚀为主、熔化烧蚀及热化学烧蚀为辅, 其烧蚀程度最为严重; 收敛段为机械剥蚀和热化学烧蚀, 其烧蚀程度次之; 而扩散段则主要发生热化学烧蚀, 其烧蚀程度最低。

Thermal Shock and Ablation Behavior of Tungsten/Rhenium Alloy Nozzle Produced by Shrouded Plasma Spray Forming

W-5%Re composite feedstock was fabricated by coating method, and W/Re alloy nozzle (inner diameter of 8 mm, length of 30 mm and wall thickness of 16.5 mm) for an experimental solid rocket motor was produced by plasma spray forming (PSF) followed by vacuum sintering. The resistance of thermal shock and ablation property of the W/Re alloy nozzle was investigated by firing tests of a small solid rocket motor (SRM). Research shows that a lamellar structure consisting of vertical columnar grains was found in PSF deposits with relative density of 87.5%. After vacuum sintering at 2 300 ℃ for 480 min, the lamellar structure was transformed into granular one, with the relative density increased to 98.6%. The comprehensive mechanical property was greatly improved. After firing tests, the nozzle had a complete form with no bursting and breaks, indicating that the W/Re alloy nozzle has good resistance to thermal shock and ablation. The line ablation rate of the nozzle was only 0.15 mm/20 s. The results of SEM and EDS analysis showed that the nozzle throat has the most serious ablation due to a combined effect of mechanical denudation, melt ablation and thermochemistry ablation. The ablation of the convergent section was less serious because of mechanical denudation and melt ablation. The ablation of the dilation section was the slightest as only thermochemistry ablation took place there.