Method of producing a brush

A method of producing a brush configured to transmit electric current between a stationary part and a moving counterpart, the method comprising:

• a) dry mixing of powders to obtain a dry powder mixture comprising, in weight percent (wt. %):
• 0.5-5 wt. % in total of graphene and/or reduced graphene oxide;
• and
• balance copper or copper alloy powder having an average particle size of 10-500 micrometers (μm);
• b) consolidating the dry powder mixture to form a composite material by subjecting the dry powder mixture to one of:
• hot isostatic pressing at a temperature of 650 to 950 degrees Celsius (C) and under a pressure of 100 to 200 megapascal(MPa) for at least 1 hour;
• or
• spark plasma sintering at a temperature of 650 to 950° C. and under a pressure of 10-100 MPa for at least 2 minutes;
• c) cold working of the composite material;
• and
• d) forming the brush from the cold worked composite material.