Surface morphology and structure of electroless ternary NiWP deposits with various W and P contents

Influence of the Tungsten Content on Surface Properties of Electroless Ni-W-P Coatings

“…As the tungsten concentration in the plating bath increases from bath 1 to 5 the Ni (200) peak becomes less intense and the Ni (111) increases, indicating that the incorporation of tungsten into the Ni-P matrix modify its crystallization behavior. A similar finding was reported by Balaraju et al 22 for Ni-W-P deposits obtained by electroless deposition. When the phosphorus contents decrease and tungsten increases the crystalline character of the film is enhanced and the intensity of the Ni (111) reflection becomes stronger.…”

“…It is seen that the Ni/P increases from baths 1 to 5 due to the reduced phosphorus concentration. The gradual increase of tungsten concentration makes the Ni/W and P/W ratios decrease from baths 2 to 5, confirming the results reported by Balaraju et al 22 . Film thickness was assessed by analyzing SEM micrographs of the cross-sections of the deposited films.…”

“…The specimens were first subject to an annealing treatment at 400°C in tubular furnace under air for 1 h. This temperature was chosen based on literature reports which indicate that the precipitation of Ni 3 P occurs at this this temperature 19,22 . The measurements were made using a Rigaku DMAX-2000 diffractometer with Cu-kα radiation in the 2θ range from 10° to 70°.…”

“…As tungsten incorporated into the film, the phosphorus content progressively diminished, as expected. According to Balaraju et al 22 , the decrease of phosphorus content as tungsten is added to electroless baths used to produce Ni-W-P films would be due to the increase of metals to hypophosphite ratio in the bath. Furthermore, these authors hypothesize that competitive reactions between tungsten and phosphorus compounds can take place or the formation of complex compounds could inhibit the co-deposition of phosphorus during plating.…”

“…The nucleation rate is a function of bath composition, pH, temperature and impurities, whereas the growth rate depends on the concentrations of the species in the plating bath [31][32][33] . Nodular structure is favored by a high nucleation rate during deposition 22 . When the tungsten concentration was further increased (bath 5), the nodular morphology was remarkably enhanced as shown in Fig.…”