Fabrication and synthesis of electroless nickel-phosphorus coatings reinforced by incorporated chromium carbide-nickel-chrome particles

An investigation was conducted to inspect the wear and fabrication of chromium carbide-nickel-chrome particles incorporated into the nickel phosphorus. St37 steel was selected to be the base and a comparison between the base and coating properties was made. The optimized parameters regarding efficiently coating the second phase particles, such as deposition rate and particle distribution in the surface and cross-section, were determined. The best heat treatment cycle for obtainingmaximum hardness and wear resistance was heating the samples for one hour at 400 degrees C in a furnace and cooling them all to room temperature. Evaluation and inspection of the final coated samples was conducted by X-Ray Diffraction and Scanning Electron Microscopy equipped with an EDAX analyzer and microhardness tester. Composite coatings containing 22% chromium carbide nickelchrome as the second phase showed the highest wear resistance on a low Carbon steel base, in comparison with other electroless composite coatings and electroless Ni-P, and after heat treatment for one hour at 400 degrees C, these coatings with 40 mu m average thickness had microhardness of nearly 1000 Vickers.