Method for preparing ohm contact electrode made from temperature sensing ceramics

Abstract

Aluminium powder or zinc powder is brought by compressed gas in supersonic speed to spray coat on surface of temp sensing ceramics forming ohmic contact resistances in the cold air dynamic spray coating method. The specific technical parameters are as following: spray coating distance 5-15 mm, gas pressure 1.5-2.5 Mpa, gas temp 200-500 deg.C, gas flow 15-30 g / s, powder size 300-500 screen meshes. The method possesses the advantages of close contact between PTC and ceramics, even compact coating layer. Moreover, the structure of metal powder is not affected by heat in coating process. Oxygen adsorbed on surfaces of ceramics is eliminated and oxidation of metal electrodes is avoided.

Description

technical field [0001] The invention relates to the surface treatment of heat-sensitive (PTC) ceramic components, in particular to a preparation method of heat-sensitive ceramic ohmic contact electrodes. Background technique [0002] Thermosensitive (PTC) ceramic components have the law of resistance changing with temperature and constant temperature heating characteristics, and have been widely used in the fields of electronics industry and household appliances. In the past few decades, people have done a lot of research on PTC ceramics. research work. The performance of PTC ceramics not only depends on the characteristics of the material itself, but also has a close relationship with the ohmic contact electrode on the surface of the PTC ceramics. There is an interface adsorbed oxygen layer or interface layer at the contact part between the metal and the PTC ceramic surface, which leads to an increase in contact resistance and affects Use of PTC components. [0003] In re...

AI Technical Summary

Problems solved by technology

Document 2 (He Xiaoming, Liu Shengli, Zhang Shaobin, etc., Functional Materials, 1996,27 (5): 407) introduces the ohmic contact electrode for PTC semiconducting ceramics, and its method is to adopt the firing infiltration method to prepare the ohmic contact electrode. The shortcoming of this method exists It is because the metal elements that form the electrode in the metal electrode slurry are easily oxidized during the infiltration process; while the process of preparing PTC ceramic electrodes by thermal spraying method also has the problem of electrode oxidation that affects the quality of the electrode

[0004] The formation of ohmic contact between the metal electrode and the PTC ceramic surface not only eliminates the adsorbed oxygen on the surface of the ceramic piece, but also prevents the oxidation of the metal electrode. The PTC ceramic electroless Ni plating and silver-coated electrodes used in general production have oxidation resistance and heat resistance. Shortcomings such as poor fatigue, Journal of Inorganic Materials 1997, Vol.12, No.4 reported the effect of electroless nickel plating on BaTiO 3 Influence of base ceramic PTC effect;

[0005] At present, the preparation of PTC ceramic ohmic contact electrodes by cold gas dynamic spray method (Cold Gas Dynamic Spray Method) has not been reported yet.

Images