Microstructure and properties of vacuum electron beam facing CuCr25 contact material

The copper chromium composite coatings produced by the electron beam facing in the vacuum on the cooper substrate have been investigated. The effect of the electron beam facing on the structure and the properties of the coatings has been determined. The chromium based solid solution containing 2, 5-4, 5% at. Cu and the copper based solid solution containing 3-5% at. Cr form in process of the electron beam facing by means of the rapid crystallization of the melting zone. As a result of the electron beam facing, two of the dimensiontype is appears in the surfaced coat (the bimodal distribution): the dendritic chromium is formed during solidification (the primary chromium particle), and the chromium precipitating at the boundaries and the within of the grain (the secondary chromium particle) as a result of age hardening of the solid solution of the copper based material. The commercial arc blowout vacuum chambers were fabricated using Cu75Cr25 contacts faced by electron beam and then passed the tests at Inc “Minusinsk vacuum switch factory - Elektrocomplex”, Minusinsk, RF. The test data exhibit that the electron-beam technology of making the contacts of the vacuum chamber proves to be efficient in improving breaking capacity of vacuum interrupters without sacrificing their other service characteristics.