INFLUENCE OF DIFFERENT FACTORS ON THE MORPHOLOGY OF THE WC COATINGS’ SURFACES DEPOSITED BY THE ION-PLASMA METHOD

Abstract

It was studied the morphology of the WС coatings’ surfaces formed by the ion-plasma method on the substrates of БрАЖ9-4 tinless bronze and 12Х18Н9Т stainless steel. Initially, the substrate had the same roughness. The coatings were formed by spraying a lot of cathodes-targets made of BA brand tungsten and ОСЧ 7-3 spectral-pure graphite. The coating thickness was 8 ... 9 μm. The scanning electron microscope РЭМ 106 investigated the surface morphology of various areas of both the substrates and formed coatings. It is revealed the features of the morphology of the substrates and WC coatings’ surfaces determined by the composition of the substrate as well as the remoteness of the investigated area from its edge. It is noted that, regardless of the substrate material, the coatings consist of a multitude of grains, the sizes of which vary in the same limits of 0.5 ... 3 μm. However, in the case of a coating formed on a bronze substrate, grains with a size of 2 ... 3 μm quantitatively predominate. At the same time, the coatings formed on the steel substrate, the size of the predominant grains do not exceed 1 μm. At the edge of the bronze substrate, the grain size varies over a wider range of 0.5 ... 5 μm. The size of the predominant grains is 2 ... 5 μm. It was concluded that one of the main factors affecting the morphology of tungsten carbide coatings is the surface roughness of the substrate based on the analysis of the surface morphology of the substrates before and after their ionic cleaning. That roughness of the substrate arose during its ionic cleaning before forming the coating. Attention is drawn to the fact that the difference in the sputtering coefficients of the elements that form the substrate is of particular importance. This difference in coefficients predetermines the peculiarities of the surface morphology of the substrate after cleaning, which is confirmed by the literature data on the sputtering coefficients of the elements (Fe, Cr, Ni, Ti, Cu, Cu, and Fe) that are part of the applied bronze and steel grades. In addition, the concentration of the electric field at the edge of the substrate plays an important role in cleaning the substrate and coating formation

Keywords

• износостойкие покрытия
• карбид вольфрама
• ионно-плазменный метод
• морфология поверхности