热处理对Pt-PtRh13薄膜热电偶绝缘层性能的影响及机理分析

为了测量航空发动机高温部件表面温度,利用离子束溅射镀膜技术制备了拥有多层薄膜结构的Pt-PtRh13薄膜热电偶,包括Ni基合金基底、Ni Cr Al Y黏结层、Al2O3过渡层、Al2O3绝缘层、Pt/Pt Rh13薄膜热电偶和Al2O3保护层。研究了热处理对Pt-PtRh13薄膜热电偶绝缘层性能的影响,并利用扫描电子显微镜(SEM)、X射线衍射分析(XRD)等手段对薄膜热电偶绝缘层性能下降的机理进行了分析。研究结果表明:利用Al2O3绝缘薄膜开发的Pt-PtRh13薄膜热电偶只用于900℃以下测温,在900℃以上长时间应用可能会出现测温不稳定问题,高温诱发Al2O3绝缘层发生晶型转变是主要原因。

Effects of Heat Treatment on Performance of Pt-PtRh13 Thin-film Thermocouple Insulating Layer and Its Mechanism Analyzing

In order to measure surface temperature of aeroengine high temperature components, Pt-PtRh13 thin-film thermocouples are fabricated by ion beam sputtering technique. The samples are multi-layer structures which are composed of Ni-based super alloy substrates NiCrAlY buffer layerAl2O3 layer Al2O3 insulating layerPt-PtRh13 thin-film thermocouple and Al2O3 protecting layer. The effects of heat treatment on the properties of Pt-PtRh13 thin-film thermocouple insulating layer and the degradation mechanism about Al2O3 insulating layer were analyzed using SEMXRD. The results show that Pt-PtRh13 thin-film thermocouple using Al2O3 insulating layer are compliant with measuring surface temperature below 900° and maybe cause instability trouble when using in more than 900°environment longtime. High temperature is the main reason that induces crystal phase transition of Al2O3 insulating layer.