纳米氧化铝作为第三层对热障涂层中热生长氧化物层的改善

摘要

在热障涂层的顶层与连接层界面之间会生成热生长氧化物层.当涂层热暴露在空气中时,这种热生长氧化物的生长会导致陶瓷层与连接层的剥落.研究了4种大气等离子喷涂热障涂层在空气中的耐高温氧化性能.将这4种涂层放在1000℃的电炉中在空气下分别保温24、48和120 h.组织观察表明,在纳米NiCrAlY/YSZ/纳米Al2O3涂层中,热生长氧化物层的生长速率远比其它3种涂层中的低.EDS和XRD分析表明,在热生长氧化物(Al2O3)涂层上,生成了Ni(Cr,Al)2O4混合氧化物(尖晶石型)和NiO,在纳米NiCrAlY/YSZ/纳米Al2O3涂层中,这种生长在Al2O3层上的有害混合氧化物层的厚度比在其它涂层中的低很多.%A thermally grown oxide (TGO) layer is formed at the interface of bond coat/top coat.The TGO growth during thermal exposure in air plays an important role in the spallation of the ceramic layer from the bond coat.High temperature oxidation resistance of four types of atmospheric plasma sprayed TBCs was investigated.These coatings were oxidized at 1000 ℃ for 24,48 and 120 h in a normal electric furnace under air atmosphere.Microstructural characterization showed that the growth of the TGO layer in nano NiCrAlY/YSZ/nano Al2O3 coating is much lower than in other coatings.Moreover,EDS and XRD analyses revealed the formation of Ni(Cr,Al)2O4 mixed oxides (as spinel) and NiO onto the Al2O3 (TGO) layer.The formation of detrimental mixed oxides (spinels) on the Al2O3 (TGO) layer of nano NiCrAlY/YSZ/nano Al2O3 coating is much lower compared to that of other coatings after 120 h of high temperature oxidation at 1000 ℃.