METHOD TO PRODUCE CHROME AND COPPER-BASED ELECTRIC CONTACTS Russian patent published in 2011 - IPC H01H1/02 

FIELD: electricity.

SUBSTANCE: in method to make chrome and copper based electric contacts, including rolling chrome powder particles with balls in mill drum with further detection of minimum gap value D_t.proc. between chrome particles in frame of test pellet soaked with alcohol, which is pressed with height from 2.0 to 4.0 mm at constantly selected pressure P_spec from the range of 3.0-6.0 t/cm² and their value comparison with value of minimum gaps between chrome particles in a similar test pellet made by pressing from chrome powder of initial raw materials D_t.init. at the same pressure P_spec., considering the processed powder good if its is not below 1.4, preparation of charge by mechanical mixing of powders of processed chrome and copper, pressing and preliminary recovery in atmosphere of live dehydrated hydrogen with soaking at temperature of 250-700°C, liquid-phase sintering at temperature of 1100-1250°C in atmosphere of live dehydrated hydrogen or solid-phase sintering at temperature of not more than 1050°C in atmosphere of live dehydrated hydrogen or in vacuum, additional heating of items to the temperature of 300-950°C in atmosphere of hydrogen and settling in closed stamp, according to proposed solution, chrome powder particles are rolled for 25-27 hours in mill drum at the ratio of balls or rolling solids weight and powder making 1:2, coefficient of drum fill of not more than 0.4, frequency of drum rotation 0.4-0.65 N_rot, min-1 where N_rot =42.4/√D, D - drum diametre, m.

EFFECT: optimisation of electric contacts making process, achievement of stable electric parametres of contacts, higher electric conductivity and evenness of chrome and copper-based contacts structure to improve their switching resource by application of procedures helping to enlarge initial powder chrome particles with reduction of their surface roughness.

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