AN ACTIVATION OF ELECTROLESS PROCESS OF Ni-P DEPOSITING ON AUSTENITIC STAINLESS STEEL

Since, it is very difficult to form Ni-P deposit by electroless process on austenitic stainless steel as substrate, the activation with a weak acid etch, i.e., nickel strike should be applied. In this work a new method for Ni-P depositing on austenitic stainless by electroless processing is developed. In this way was avoided nickel strike pre-coating treatment which makes Ni-P coating process on stainless steel more complicated in comparison to other similar electroless processes on other types of steel, aluminium alloys, and so on. Study has been focused on influence of new activation process on adhesivity, microhardness and microstructure analysis of electroless Ni-P coatings. Adhesivity was estimated by Vickers indenter. Microhardness was tested by using scanning electron microscope. Microstructure of the electroless treated specimens were analyzed by optical and scanning electron microscopy. Based on experimental results, it can be concluded that by new method of activation of surface, electroless nickel - phosphorous coatings on austenitic stainless steel have higher adhesivity and microhardness than non-activated electroless nickel - phosphorous coatings.