Multilayer co-sintered Pt thin-film strain gauge for high-temperature applications

Abstract

Typical high-temperature thin-film sensors are fabricated by layer-by-layer deposition and layer-by-layer sintering, which are time and energy consuming. In this study, thin-film strain gauges (TFSGs) were fabricated on superalloy substrate by co-sintering process for the first time. The co-sintering behavior of glassy insulating layer and Pt thin-film resistance grid was studied. Compared with layer-by-layer sintering, the weak interface constraint between the top and sub layers of co-sintered TFSG allows the free in-plane shrinkage of the Pt resistance grid. In the co-sintering process, the glassy SiO2 in the insulating layer fills the pores in the Pt resistance grid, significantly improving the compactness. Further, no Pt element diffuses into the insulating layer. Owing to the remarkable advantages of the co-sintering process, the co-sintered Pt TFSG not only inherits the high-temperature insulation (2.8 MΩ at 800 °C) of the layer-by-layer sintered insulating layer, but also significantly increases the high-temperature stability of the Pt grid resistance; the resistance change rate of layer-by-layer sintered samples at 800 °C is 7.3 % h−1, while that of co-sintered samples at 800 °C is only 0.9 % h−1. Finally, the high-temperature strain response of co-sintered Pt TFSG up to 800 °C was tested.