Plasma Nitriding Mechanisms of Low-Density Sintered Metal Products
-
E. Roliński
and
M. Woods
Abstract
The mechanism of plasma nitriding include the formation of various active species generating nitrogen atoms reacting with the metal. Which species prevail in supplying nitrogen depends on nitriding conditions as well as the nature of the treated metal. Plasma nitriding of low-density powder metal (PM) products results in a formation of the layers whose thicknesses may depend on the gas pressure used for the process. Higher pressure can cause locally deeper penetration of the surface by active nitrogen species formed from ammonia compounds generated by the plasma. While a low processing pressure reduces this effect significantly. The formation mechanism of a locally thicker layer relies on the presence of open porosities in the surface as they can be penetrated by the ammonia species generated by the plasma. The same porosities cannot be penetrated by the ions of nitrogen formed at the same time since their mean free life is much shorter than that of ammonia species. ◼
Kurzfassung
Der Mechanismus des Plasmanitrierens beinhaltet die Bildung verschiedener aktiver Spezies, die atomaren Stickstoff an der Metalloberfläche bereitstellen. Welche Spezies bei der Stickstoffzufuhr überwiegen, hängt von den Nitrierbedingungen sowie von der Art des behandelten Metalls ab. Das Plasmanitrieren von Produkten aus Pulvermetall (PM) mit geringer Dichte führt zur Bildung von Schichten, deren Dicke vom verwendeten Gasdruck abhängen kann. Ein höherer Druck kann eine lokal tiefere Durchdringung der Oberfläche durch aktive Stickstoffspezies verursachen, die aus den vom Plasma erzeugten Ammoniakverbindungen beruht. Ein niedriger Prozessdruck reduziert diesen Effekt deutlich. Der Mechanismus der Bildung einer lokal dickeren Schicht beruht auf dem Vorhandensein von offenen Porositäten in der Oberfläche, da diese von den durch das Plasma erzeugten Ammoniakspezies durchdrungen werden können. Die gleichen Porositäten können nicht von den gleichzeitig gebildeten Stickstoffionen durchdrungen werden, da deren mittlere freie Lebensdauer viel kürzer ist als die der Ammoniakspezies. ◼
References
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Articles in the same Issue
- Inhalt/Contents
- Influence of the Material State of Ground, Case-Hardened Steels on the Barkhausen Noise Depending on the Surface Integrity*
- Suitable Material Selection for Large Size Cylindrical Gears*
- Experimental and Numerical Investigation of the Surface Layer Conditions after Carbonitriding of Powder Metallurgical Steels. Part 1: Diffusion in Components of Graded Porosity
- Plasma Nitriding Mechanisms of Low-Density Sintered Metal Products
- Heat Transfers Coefficients of Directly and Indirectly Cooled Component Areas during Air-Water Spray Cooling
- Impressum/Imprint
- From and for Practice / Praxis-Informationen
- AWT-Info / HTM 01-2021
- HTM Praxis
Articles in the same Issue
- Inhalt/Contents
- Influence of the Material State of Ground, Case-Hardened Steels on the Barkhausen Noise Depending on the Surface Integrity*
- Suitable Material Selection for Large Size Cylindrical Gears*
- Experimental and Numerical Investigation of the Surface Layer Conditions after Carbonitriding of Powder Metallurgical Steels. Part 1: Diffusion in Components of Graded Porosity
- Plasma Nitriding Mechanisms of Low-Density Sintered Metal Products
- Heat Transfers Coefficients of Directly and Indirectly Cooled Component Areas during Air-Water Spray Cooling
- Impressum/Imprint
- From and for Practice / Praxis-Informationen
- AWT-Info / HTM 01-2021
- HTM Praxis
