Introduction.
This work set a problem of formation of the surface electrically conductive composite layer resistant to high-temperature oxidation, possessing high adhesion to the metal surface of the connector and having low contact electrical resistance in a range of temperatures from 20 to 950°C [1, 2].
The model of the contact layer between elements of the electrical connectors, including formation of adhesively-resistant electroconductive layer, barrier layer (resistant to high-temperature oxidation), and formation of the thin-film composite heat resisting layer with low electrical resistance in the direction normal to the coating plane on the surface of one of the metal elements, was developed for this purpose.
Experimental.
Alloy (29 % Ni, 18 % Co, 52 % Fe) was chosen as the basic material for the samples fabricated in the form of cores.
The following works were performed:
1) choice of ways for formation of heat resisting surface layers;
2) fabrication of samples with coatings;
3) study of physical and mechanical properties of the coatings, including, electrical conductivity.
Result and Discussion.
Resistance of the transition zone of the contact pair with the offered coating is 30 times less, than the resistance of the sample without coating after heating up to 800°C.
The coating obtained by physical evaporation in vacuum, is rather homogeneous. It has fine grained structure and chemical composition reproducible from the sample to the sample. The coating structure is permanent after heating.
Conclusion.
Operability of the model with barrier galvanic and external (PVD) heat resisting electroconductive layers in a heating-cooling cycle in the temperature range of 20-900°C was demonstrated by the results of comparison of several variants of the surface layer materials, by criteria of minimum electrical resistance of the contact pair and contact mechanical durability of the coatings.
Reference.
1. Smirnov Yu., Sobko S., Sorokin A., Tkachenko A. Fuel cells and power plants on their basis: Theses of the reports for III ALL-RUSSIA WORKSHOP. – Ekaterinburg, 2006. – 238 p. P. 98-100.
2. Fakrutdinov A., Tcherepanov V., Yao I. Glass and ceramics. - # 6, 1998. - p.24.2 |