Wear behavior of Ni-B electroless films on a steel S7

摘要

Wear resistance of materials is a very important aspect from the economic point of view, since lack of wear resistance is one of the important ways for materials to lose utility. To improve wear resistance of materials that are in relative movement, one against other, several methods can be applied. One method that is gaining importance is the application of electroless films, being the Ni-B electroless plating a relatively new way to obtain high wear resistance films on metals. In this work, the wear tests results of the film of Ni-B in its amorphous state and after different heat treatments are presented. The heat treatments were done from 200°C to 550°C with intervals of 50°C. The film Ni-B was characterized by optical microscopy, scanning electron microscopy (SEM), X-ray diffraction and microhardness. Results of X-ray diffraction shown that the film without heat treatment is amorphous, and after the heat treatments, intermetallic Ni{sub}3B precipitates are formed, which can be the cause of the increase of the hardness of the film Ni-B. Surface characterization by SEM of Ni-B films obtained at different immersion time, shown that deposits have cellular morphology and as treatment time increases, morphology becomes nodular. The greater hardness Vickers is obtained for the heat treatment at 215°C and 36 hours.