Study on the surface morphologies of nickel-phosphorus ultra-black films

Ni-P ultra-black films having conical pores with the diameter of similar to 10-30 mu m and the depth of similar to 15-30 mu m were prepared by chemical etching of electroless plated Ni-P films using 8 mol/L nitric acid at 40 degrees C for 60 s. The phase composition and microstructure of the film samples were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results show that the diameter and depth of the etching pores become larger and the flat top regions bounded by etching pores become smaller by the coalescence of adjacent pores with the increase of etching time. The surface morphologies of the etched Ni-P films are characterized by the distribution of conical pores.