Effect of plasma nitriding on the strength of fine protrusions formed by sputter etching of AISI type 420 stainless steel
| Autor: | Rongguang Wang, Akihiro Yamamoto, Keijiro Nakasa, Tsunetaka Sumomogi |
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| Rok vydání: | 2015 |
| Předmět: |
Materials science
Scanning electron microscope Metallurgy Surfaces and Interfaces General Chemistry Martensitic stainless steel Nitride engineering.material Condensed Matter Physics Indentation hardness Surfaces Coatings and Films Sputtering Indentation Vickers hardness test Materials Chemistry engineering Nitriding |
| Zdroj: | Surface and Coatings Technology. 272:298-308 |
| ISSN: | 0257-8972 |
| DOI: | 10.1016/j.surfcoat.2015.03.048 |
| Popis: | Argon ion sputter-etching of AISI type 420 martensitic stainless steel was carried out to form conical protrusions with bottom diameter of 10–30 μm on the specimen surface by using a radio-frequency magnetron sputter-apparatus. Plasma-nitriding was applied to the protrusions with various mixing rate of nitrogen and argon gas. The shape of the protrusions was examined by using a scanning electron microscope, and the nitrides formed on the protrusions were identified by means of an X-ray diffraction analysis. Micro-Vickers hardness tests and nano-scratch tests were used to evaluate the deformation resistance of the protrusions. By plasma-nitriding at a nitrogen pressure of 130 Pa and a nitriding power of 50 W, about 1.3 times larger indentation resistance than that of the as-sputter-etched protrusions was obtained after a long nitriding time of 14 ks. When plasma-nitriding was carried out at a lower nitrogen pressure of 1.2 Pa and a higher nitriding power of 200 W for 7.2 ks, indentation and scratch resistances of the protrusions largely increased to the values almost three times as large as those of the as-sputter-etched protrusions. However, the protrusions were brittle due to the formation of thick nitride layers and the sharpness of the protrusions was lost. Reduction of the nitriding power to 50 W recovered the sharpness with small amount of surface nitride layer, but the indentation resistances were only 1.4 times larger values than those of the as-sputter-etched protrusions. On the other hand, plasma-nitriding using a mixture of nitrogen gas of 0.53 Pa and argon gas of 0.67 Pa at the power of 50 W produced almost twice larger indentation and scratch resistances than those of the as-sputter-etched protrusions within a short nitriding time of 1.8 ks, retaining the sharpness of protrusions without forming brittle nitrided layers. |
| Databáze: | OpenAIRE |
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