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目前,已研制成表面热电偶,供气体涡轮发动机内高温测量之用。在涡轮机的结构部件表面上,镀上一层金属、经氧化后,该金属表面形成一层牢固的,绝缘能力很好的氧化物薄层。将标准的铂、铂铑合金直接溅射到金属氧化物薄层上,获得了热电偶热接点阵列和电极导线。由于这些热电偶的厚度只有0.0001～0.0002英寸(0.0025～0.005毫米),它们对构件表面的附面层以及从气体流向构件内部的热流或构件内部出现的热流都不会造成明显的干扰。这种热电偶已在燃烧室排出气体中作了很多次测量,结果表明它们十分耐用。本文评述这种热电偶的冶金特性、固态特性以及流向热电偶的热传导过程。讨论了热电偶的精度和耐久性。介绍一些在简单的圆柱表面和气体涡轮机导流翼片表面上溅射成的薄膜热电偶的实例。
Currently, surface thermocouples have been developed for high temperature measurements in gas turbine engines. On the surface of the structural part of the turbomachine, a layer of metal is plated and, upon oxidation, the metal surface forms a firm, highly insulating layer of oxide. The standard platinum, platinum and rhodium alloy sputtering directly to the metal oxide thin layer, the thermocouple hot junction array and electrode leads. Since these thermocouples have a thickness of only 0.0001 to 0.0002 inches (0.0025 to 0.005 mm), they do not cause significant interference with the surfacing of the component surface and the heat flow from the gas flow inside the component or inside the component. The thermocouple has been measured many times in the combustor’s exhaust gas and the results show that they are very durable. This article reviews the metallurgical properties, solid state properties, and thermal conduction of thermocouples to such thermocouples. The accuracy and durability of thermocouples are discussed. Some examples of thin film thermocouples sputtered on simple cylindrical surfaces and on the surface of a gas turbine guide vane are presented.