Two-Layer Copper-Based Powder Electrocontact

• Published in: Inorganic materials : applied research 2022, Vol.13 (3), p.818-822
• Main Authors: Meilakh, A. G., Kontsevoy, Yu. V., Gilev, I. O., Shubin, A. B.
• Format: Article
• Language: English
• Subjects: Activated carbon; Adhesive strength; Aluminum oxide; Chemistry; Chemistry and Materials Science; Compacting; Composite Materials; Composition; Contact stresses; Copper; Electric contacts; Electrical resistivity; Heat treatment; Hoppers; Industrial Chemistry/Chemical Engineering; Inorganic Chemistry; Materials Science; Mixtures; Sintering (powder metallurgy); Specific gravity; Thickness
• ISSN: 2075-1133; 2075-115X
• DOI: 10.1134/S2075113322030248

The influence of various schemes of pressure treatment (pressing, rolling) and modes of heat treatment of powder mixtures on the service properties and adhesion strength of the working and current-carrying layers of electrical contacts with a conductivity of at least 75% of the copper conductivity was studied. The dependence of the permissible fraction of the working layer in the total contact thickness on its resistivity was established. It was calculated that, in the created contacts, the thickness of the working layer of two compositions 97% Cu + 1% C A + 2% PA (1) and 97.5% Cu + 1% C A + 0.5% PA + 1% Al 2 O 3 (2), with the electrical resistivity of 3.20 and 3.28 μΩ cm, respectively, can be increased to the thickness of the copper layer (here, C A is activated carbon; PA is a (Fe–Cu) nanocrystalline pseudoalloy). Among the considered processes, we determined the optimum method to fabricate contacts that consists of combined rolling with a reduction of 50% of copper powder and the powder mixture for the working layer using the metering hoppers separated for the charge of each layer, reducing sintering at 600°C for 1 h, and re-compacting rolling with strain of 85% and sintering at 800°С for 1 h. This technique was used to obtain samples of contacts with working layers of two compositions with a relative density of 0.99 and 0.98, hardness HB of 990 and 830 MPa, and electrical resistivity of 2.57 and 2.61 μΩ cm, respectively. The adhesion strength of contact layers is more than 200 MPa (breaking stress for copper).