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研究预先真空氧化处理工艺对耐高温涂层的热生长氧化物(TGO)相变的影响,用超音速火焰喷涂技术在镍基合金基底上喷涂CoCrAlY耐高温腐蚀涂层,然后对其进行特定的预先真空氧化处理。研究表明:未预先真空氧化处理试样在高温氧化初始阶段,TGO中除了含有Al2O3,还含有大量的Cr2O3、CoO和尖晶石类氧化物,而且Al2O3的形成量主要取决于氧分压。CoCr2O4尖晶石的形成阶段主要在高温氧化的初始高氧分压阶段和随高温氧化进行的化学反应阶段。经过适当的预先真空氧化处理后,TGO的主要成分为低Y含量的Al2O3,零星分布着高Y含量的Al2O3,未观察到明显的大晶粒尖晶石结构氧化物;随着高温氧化时间的延长,少量多孔状的CoCr2O4尖晶石和Cr2O3零星分布于连续的Al2O3周围。另外,TGO的生长率比未预先真空氧化处理的低。
The effect of pre-vacuum oxidation process on the phase transition of TGO in high temperature resistant coatings was studied. The CoCrAlY high temperature corrosion resistant coating was sprayed on the Ni-based alloy substrate by supersonic flame spraying technique, and then the specific Pre-vacuum oxidation. The results show that: In the initial stage of high temperature oxidation, the TGO contains a large amount of Cr2O3, CoO and spinel oxides besides the Al2O3 in the initial stage of high temperature oxidation. The formation amount of Al2O3 mainly depends on the oxygen partial pressure. The formation phase of CoCr2O4 spinel is mainly in the initial high oxygen partial pressure stage of high temperature oxidation and the chemical reaction stage with high temperature oxidation. After appropriate pre-vacuum oxidation, the main components of TGO are low Y content Al2O3, sporadic distribution of high Y content Al2O3, no obvious large grain spinel structure oxide; with the high temperature oxidation time Extend, a small amount of porous CoCr2O4 spinel and Cr2O3 sporadic distribution around the continuous Al2O3. In addition, the growth rate of TGO is lower than that of the non-vacuum oxidation treatment.