Influence of current type on tribological and corrosion properties of nickel boron coatings produced by electrodeposition

In the present work, Ni-B alloys were successfully coated on the low carbon steel substrate from a modified watt type bath with direct current, pulse current and pulse reverse current. Effects of current type on microstructure and surface morphology were characterized via scanning electron microscopy. Crystallographic orientation, lattice distortion and grain size changing with different current type were investigated with X-ray diffraction. High lattice distortion and lower grain size performed with pulse current and pulse reverse current type respectively. Mechanical studies imply that pulse current type provides the highest microhardness values. Tribological properties of alloys carried out reciprocating sliding wear tests. Reciprocating sliding wear tests evidenced that the alloy coatings deposited by using pulse current and pulse reverse current demonstrated substantial advancement in mechanical properties and wear resistance because of the current type. Pulse current and pulse reverse current provide higher wear resistance when compared with plating produced via direct current. According to the corrosion test results, the highest corrosion resistance was obtained by direct current, and the lowest corrosion resistance was obtained by pulse reverse current. The result is that the grain size is the main factor for corrosion resistance.