Characteristic features of austenitic steel grades combine a good corrosion resistance with a low hardness, wear resistance and scratch resistance. An interesting possibility for improving the wear behaviour of these ...Characteristic features of austenitic steel grades combine a good corrosion resistance with a low hardness, wear resistance and scratch resistance. An interesting possibility for improving the wear behaviour of these steels without loss of their corrosion resistance lies in enriching the near surface region with nitrogen. The process of a solution nitriding allows the rise of the solution of nitrogen in the solid phase. On this state nitrogen increases the corrosion resistance and the tribilogical load-bearing capacity. The aim of the study was, to investigate the improvement of the pitting corrosion behaviour by solution nitriding. A special topic was to observe the effect of nitrogen by different molybdenum content. So austenitic stainless steels (18% Cr, 12% Ni, Mo gradation between 0.06 to 3.6%) had been solution nitrided. The samples could be prepared with various surface content of nitrogen from 0.04 to 0.45% with a step-by-step grinding. The susceptibility against pitting corrosion of these samples had been tested by determination of the stable pitting potential in 0.5M and 1M NaCl at 25°C. For the investigated steel composition and the used corrosion system there is no influence of molybdenum on the effectiveness of nitrogen. The influence of nitrogen to all of the determined parameters can be described well by PRE = Cr + 3,3 * Mo + 25 *N. XPS analysis of the sample surfaces support the results of the pitting corrosion tests.Additionally surface investigations with an acid elektolyte (0,1M HC1 + 0,4M NaCl) were performed. In this case the passivation effective nitrogen content increases markedly with rising molybdenum concentration of the steel. Obviously an interaction of Mo and N is connected with a strongly acid electrolyte.展开更多
Anodic oxidation processes for metal surface have been utilized many materials,for example,porous alumina, nano-silicon crystal,and so on.In these materials,anodizing surface treatment for titanium or zirconium is use...Anodic oxidation processes for metal surface have been utilized many materials,for example,porous alumina, nano-silicon crystal,and so on.In these materials,anodizing surface treatment for titanium or zirconium is useful for biocompatible material,like artificial bones and joints.In anodizing behavior,successive dielectric breakdown makes the surface microscopic bumpy morphology,which is important for the biocompatibility.Electric field can promote the oxidation behavior at the anodizing surface.As the result of the anodizing experiments using titanium or zirconium plate(10mm × 10mm),it is found that the anodized film becomes thicker and the microscopic honeycomb structure becomes finer and uniform by the imposition of electric field up to 200 kV/m.展开更多
基金The DFG(Deutsche Forschungsgemeinschaft)is gratefully acknowledged for the financial support(DFG No.PA 699/3-1 and FR 1603/1-2).
文摘Characteristic features of austenitic steel grades combine a good corrosion resistance with a low hardness, wear resistance and scratch resistance. An interesting possibility for improving the wear behaviour of these steels without loss of their corrosion resistance lies in enriching the near surface region with nitrogen. The process of a solution nitriding allows the rise of the solution of nitrogen in the solid phase. On this state nitrogen increases the corrosion resistance and the tribilogical load-bearing capacity. The aim of the study was, to investigate the improvement of the pitting corrosion behaviour by solution nitriding. A special topic was to observe the effect of nitrogen by different molybdenum content. So austenitic stainless steels (18% Cr, 12% Ni, Mo gradation between 0.06 to 3.6%) had been solution nitrided. The samples could be prepared with various surface content of nitrogen from 0.04 to 0.45% with a step-by-step grinding. The susceptibility against pitting corrosion of these samples had been tested by determination of the stable pitting potential in 0.5M and 1M NaCl at 25°C. For the investigated steel composition and the used corrosion system there is no influence of molybdenum on the effectiveness of nitrogen. The influence of nitrogen to all of the determined parameters can be described well by PRE = Cr + 3,3 * Mo + 25 *N. XPS analysis of the sample surfaces support the results of the pitting corrosion tests.Additionally surface investigations with an acid elektolyte (0,1M HC1 + 0,4M NaCl) were performed. In this case the passivation effective nitrogen content increases markedly with rising molybdenum concentration of the steel. Obviously an interaction of Mo and N is connected with a strongly acid electrolyte.
文摘Anodic oxidation processes for metal surface have been utilized many materials,for example,porous alumina, nano-silicon crystal,and so on.In these materials,anodizing surface treatment for titanium or zirconium is useful for biocompatible material,like artificial bones and joints.In anodizing behavior,successive dielectric breakdown makes the surface microscopic bumpy morphology,which is important for the biocompatibility.Electric field can promote the oxidation behavior at the anodizing surface.As the result of the anodizing experiments using titanium or zirconium plate(10mm × 10mm),it is found that the anodized film becomes thicker and the microscopic honeycomb structure becomes finer and uniform by the imposition of electric field up to 200 kV/m.
