Change of Surface Texture Parameters of Ground Surfaces after Application of Hard and Abrasion Resistant Layers

Continuous technology development builds to the foreground the solution of the quantification of roughness, respectively the surface texture. The surface roughness of the functional surfaces affects the durability and the reliability of the components. The surface roughness has an impact on the accuracy of machine parts running, noise, run-in time, friction loss, electrical resistance, heat transfer, fatigue strength, wear resistance and corrosion resistance (1). Grinding has still the largest share in finishing methods of functional surfaces not only in engineering, but is also used in electrical engineering. At present, the trend is to increase the functional properties of functional surfaces by applying coatings and layers. This is also related to the change in surface texture parameters, which is caused by the creation of a new surface on the original machined surface. The paper deals with the change of selected 3D parameters of the surface texture of ground steels after application of diffusion technologies. The steel CSN 41 2050 and 34CrNiMo6 after nitriding and ferritic nitrocarburizing in gas and plasma were evaluated. Selected 3D surface texture parameters were measured by the coherence correlation interferometer Talysurf CCI Lite. The change in surface texture parameters is influenced by the preparation of the substrate, i.e. the grinding parameters and the used diffusion technology, as well as the chemical composition of the used steels (2), (3). The steels were grinded with SiC abrasive papers with grain sizes of 120, 220, 600 and 1000 according to FEPA. Steel CSN 41 2050 showed the reduction of the observed surface texture parameters almost all types of surface treatments - roughness decreased. Only in the case of ferritic nitrocarburizing in gas occurred to the deterioration of surface roughness. Similar results were achieved at 34CrNiMo6 steel - ferritic nitrocarburizing in gas led to an increase of surface roughness. For other surface treatments the roughness decreased. Applied diffusion technologies increase the hardness of functional surfaces, corrosion resistance, fatigue strength, wear resistance and reduce coefficient of friction (4). The above-mentioned advantages of applied diffusion layers along with the reduction in surface roughness can contribute to wider use of these technologies in technical practice.