A method for fabricating thick-film thermocouples on three-dimensional surfaces based on laser direct writing process

Abstract

The invention discloses a method for preparing a thick-film thermocouple on a three-dimensional surface based on a laser direct writing process, and relates to the technical field of laser micromachining and film sensors. The process parameters of the composite direct writing; S3: prepare an insulating medium layer on the curved surface of the thermocouple to be prepared; S4, apply the electronic paste on the surface of the insulating medium layer with a micro-pen respectively to prepare Pt wires and PtRh wires, two The minimum included angle of the wires is not less than 45°; S5: At the hot junction of the two wires, use a laser for precise spot welding, and use a micropen to pre-prepare Pt paste at the hot junction before spot welding. The size of the thermocouple prepared by the method of the invention is between the thermocouples prepared by the thin film process and the traditional thick film process, which can make the thermocouple have good stability and fast response speed at the same time. Ability to fabricate thermocouples on curved surfaces of complex dimensions.

Description

technical field [0001] The invention relates to the technical fields of laser micromachining and film sensors, in particular to a processing method for preparing thick-film thermocouples on a three-dimensional surface based on a laser direct writing process. Background technique [0002] In aerospace vehicles, gas turbines, heavy machinery and other fields, real-time monitoring of the temperature of key parts of equipment is an important means to ensure the safe operation of equipment. These important equipment generally require that when installing sensors, the internal structure must not be damaged, otherwise it will bring new safety hazards. And as the service temperature increases, these surfaces with complex curved surfaces need to use thermal barrier coatings for thermal protection, and the sensor needs to have good compatibility with thermal barrier coatings. Therefore, the use of high-quality temperature sensors to achieve non-destructive transient temperature measu...

AI Technical Summary

Problems solved by technology

[0006] (1) When the film thickness is less than 500nm, there will be a size effect, which affects the accuracy of the thermocouple; when the film thickness is greater than 4000nm, the efficiency of the traditional thin film process is too low, and the film quality cannot be guaranteed;

[0007] (2) The commonly used magnetron sputtering technology and electron beam evaporation technology need to be carried out in a closed protective atmosphere, the hardware cost is large, and the workpiece size is limited (Li Fuguo, Huang Luquan. Research on the dynamic characteristics of thin film thermocouples[J]. Journal of Instrumentation, 1996(3):316-318.);

[0008] (3) The performance of thin-film thermocouples is greatly affected by the complexity of substrate morphology and surface roughness, so it is not suitable for non-destructive transient temperature measurement on large and complex surfaces;

[0009] (4) The structure of the film is relatively fragile, and it is easy to peel off in the scouring environment

Gao Qiaoxia.Analysis of the Influencing Factors of Screen Printing Quality[J].Guangdong Printing,2017(3):39-40.] It is difficult to accurately control the dimensional accuracy of printing;

[0015] (3) Screen printing technology is also difficult to be used in the preparation of sensors on the surface of large curved parts;

[0016] (4) The surface roughness of the workpiece will affect the performance stability of the thermocouple prepared by screen printing

Images