Thermal stability and mechanical properties of Ni-W-P electroless deposits

The ternary Ni-W-P alloy coatings were deposited by electroless plating on 420 stainless steel to evaluate the thermal property and related mechanical characteristics of the coating assemblies. The thermal stability of electr oless Ni-W-P deposits, analyzed by differential scanning calorimetry (DSC), could be enhanced by the co-deposition of tungsten as compared to binary e lectroless Ni-P films. The phase and composition of Ni-W-P and Ni-P were ev aluated by X-ray diffraction technique and electron probe microanalysis, re spectively. The co-deposition of tungsten enabled the deposits to exhibit a n amorphous structure with lower phosphorus content. Adhesion strength of t he deposits on the substrates were assessed by a scratch test. The introduc tion of the tungsten in the Ni-P coating effectively reduced the linear cra ck length and delayed the cracking formation. Surface hardness of binary al loy coating could be modified with the introduction of the tungsten element . (C) 2001 Elsevier Science B.V. All rights reserved.