Efeitos da nitretação iônica em peças de aço SAE 1020 com alta razão aresta/superfície.

Abstract

Ion nitriding is used for the hardening of metallic surfaces. In this process, a field is applied between two electrodes in environment with nitrogen or mixture under low pressure. Collisions of electrons with neutral particles produce ions that, influenced by the electric field, are accelerated to the cathode. Interaction between these ions and the metallic surface (cathode) creates a nitrided layer which has good mechanical properties. Certainly, the presence of surface edges will influence the unifonnity of the nitrided layer since the electric field is not uniform at this region. Therefore it is useful to understand how the electric field and the superficial charge density behave over the surface, mainly at the edges, corners and points, and how this effects the nitreded layer. In this sense, it was observed that cylindrical samples of different lengths, depending on the treatment conditions, presented erosion rings produced by the edge effects. Films deposited on the surface of these samples have a growth direction that changes along the surface. Furthermore, in this study, differences of thickness and hardness of the nitrided layer samples of different lengths were explained taking into account the heating rate of these samples.