Investigation of the performance of carbon fiber-reinforced CoNi coatings electrodeposited on brass substrates

Abstract

Carbon fiber is added to the CoNi plating solution to prepare the carbon fiber-reinforced CoNi coating. The influence of carbon fiber on the surface morphology, chemical composition, corrosion resistance, wear resistance and magnetic performance of the CoNi electrodeposited coating is investigated. Carbon fibers have good electrical conductivity and act as additional nucleation sites during electrodeposition, leading to an enhanced of CoNi deposition rate. The carbon fiber-reinforced CoNi coating shows smaller and finer nodular structures and is composed of 61.4 % cobalt, 25.5 % nickel and 13.1 % carbon. The addition of carbon fiber to the plating solution increases the cobalt content while decreasing the amount of nickel in the CoNi coating. Compared with the CoNi coating, the carbon fiber-reinforced CoNi coating exhibits better corrosion resistance with the most positive corrosion potential (-0.511 V) and the lowest corrosion current density (9.07 μA/cm²). The presence of carbon fiber hinders grain growth, leading to a finer, more compact grain structure, which results in higher wear resistance. Moreover, according to the magnetic hysteresis loop of the CoNi coating, the saturation magnetization of CoNi is about 83.2 emu/g while the saturation magnetization of carbon fiber-reinforced CoNi coating is approximtely 92.5 emu/g. The coercivity of the carbon fiber-reinforced CoNi coating is 468.9 Oe, which is twice as large as that of the CoNi coating.