AFM analysis on the surface of electroless Ni-B coating

Electroless plating was used to prepare Ni-B alloy deposits. It was confirmed with DSC and XRD analysis that three kinds of nickel borides are formed when the deposits are heated from 0degreesC to 500degreesC. An Atomic Force Microscope (AFM) was used to analyze the surface of Ni-B coating before and after treated in different processes. It was found that the microhardness is related to the surface topography of coating and the type of borides emerged in deposit. The microhardness HV can reach a value over 15 000MPa under certain heat treatment. In this case, nano-dimension protrusions with 40 nm similar to 100 nm in diameter and 10 nm similar to 20 nm in height were observed according to the microstructure. The mechanism of the microhardness increasing was discussed in detail.