Wyniki 1-1 spośród 1 dla zapytania: authorDesc:"Justyna Słowik"

The influence of total gas pressure and atmosphere composition during ion cleaning step on S-phase coating formation DOI:10.15199/28.2019.1.1

  Austenitic stainless steel is a commonly used construction material for applications in which high corrosion resistance is required. However, certain applications are limited by the low hardness and wear resistance of this steel. One of the ways to improve its mechanical properties is thermochemical surface treatment at temperatures up to 500°C. During low-temperature nitriding or carburizing a diffusion layer of S-phase is formed [1], which is considered to be a carbon or nitrogen supersaturated solution in austenite. S-phase is characterized by high hardness and wear resistance and its corrosion resistance is comparable to that of austenitic steel. An alternative method is to deposit S-phase as a coating on an austenitic substrate. [2, 3]. S-phase coatings can be obtained, for example, by reactive magnetron sputtering of austenitic steel in a nitrogen atmosphere. The production process consists of two main stages: an ion cleaning of the substrate followed by sputter deposition of the target material in a reactive plasma. During the ion cleaning step the substrate bias voltage is much higher than in the sputtering stage. As a result, ions reaching the substrate remove impurities instead of depositing as a coating [4]. In the case of austenitic steel, this process can lead to removal of the oxide passive layer usually present on the surface. As observed in previous research [5, 6], such a procedure can lead to diffusion layer formation as a consequence of nitrogen diffusion from the coating into the substrate. Such a diffusion layer, with nitrogen content lower than that in the S-phase coating, forms a gradient interlayer that is potentially beneficial for improving the coating adhesion. Nitrided diffusion layer formation in austenitic stainless steels has been widely studied for low-temperature gas or plasma nitriding [7÷9]. Previous research, concerning the influence of surface activation on diffusion layer formation in ther[...]

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