GH3044合金堵盖高温氧化机理研究

为了研究固体推进剂燃气对GH3044合金堵盖的作用机理,通过光学显微镜、扫描电镜、硬度测试仪等手段对GH3044合金堵盖的孔洞进行测试与分析。结果显示:在氧化性气氛下,GH3044合金出现了沿晶界的择优氧化,形成了楔形裂纹,在热应力及氧化物长大的膨胀应力作用下发生剥落并最终形成喇叭形的烧蚀孔洞;其中,燃气中的金属氧化物(PbO)沿晶界与基体中的Ni发生氧化还原反应,形成低熔点的Pb-Ni共晶,进一步加剧了GH3044合金的高温氧化。

High Temperature Oxidation Mechanism of GH3044 Alloy Blocking Lid

In order to investigate the oxidation mechanism of solid propellant projectile on GH3044 alloy, the aperture in the GH3044 alloy lid was measured and analyzed by means of optical microscope, scanning electron microscope (SEM) and micro-hardness testing. The analysis results indicate that GH3044 alloy has endured a selective oxidation process along the grain boundaries at an oxidizing atmosphere, forming wedge-shaped inter-granular cracks. Therefore, an aperture in the lid was formed by the thermal stress as well as the metal oxide expansion stress. Moreover, the metal oxide (PbO) in the projectile reacted with the Ni-matrix, forming low-melting-point Pb-Ni eutectic, which is also supposed to be responsible to have accelerated the oxidation process.