Hydrogen plasma diffusion treatment of layers prepared by plasma nitridation

Summary form only given. Annealing is applied after a nitridation process. The parameters of the nitridation process are chosen solely according to practical experiences of the equipment operator, without employing know-how concerning plot correlations among process parameters. The main aim of this paper is experimental and theoretical explanation of diffusion and structure processes occurring in plasma nitrided layers during their subsequent isothermal annealing, included into the work cycle immediately after finishing proper plasma nitridation. The substance of the experimental part is first of all quantitative determination of redistribution of interstitial elements-nitrogen and carbon-in the layer and structure and phase analysis of changes of isothermally annealed plasma nitrided layers. The results of these analyses are completed with hardness measurements, performed in parallel. On the basis of thus measured redistribution of interstitial and substitutional elements in the layer, then diffusion and phase characteristics of both groups of elements are determined and compared with the data according to literature. The thermodynamic and diffusion model of elemental redistribution in a plasma nitrided layer of finite thickness is elaborated. Further, the following properties of thin surface layers were measured: layer thickness, microhardness, roughness, wear resistance and surface morphology.