Design of pulsed plasma nitriding device and plasma nitriding of aisi 52100 steel

There are several metal surface treatment methods to improve the wear,corrosion hardness, fatigue and the surface properties of machine parts.The plasma nitriding process has become a considerable industrialinterest due to the most advantages beneficial surface propertyenhancement. Pulsed plasma nitriding process has some advantages,such as shorter process times, increasing diffusion and nitriding easily forcomplicated geometries, compared with the traditional plasma nitridingprocesses.In this study, pulsed plasma nitriding device was designed. In design, DCpower supply with 2.5 kW, stainless steel chamber, vacuum pump andvarious flanges and gaskets were used. In addition, AISI 52100 bearingsteel was pulsed-plasma nitrided at gas mixture of 50 % H2 and 50 % N2,at 500 ºC for 4 h. The dc plasma was operated with a potential differenceof 490-650 V in the frequency range 0-20 kHz. Samples were cleaned inalcohol and placed in plasma nitriding chamber. The system wasiiievacuated to 2,5x10-2 mbar. The nitriding temperature was measuredusing thermocouple, placed at the bottom of the nitrided sample. Afternitriding, the samples were cut in cross-section and prepared for standardmetallographic techniques. The X-ray diffraction indicates that the whitelayer consists of phases of Fe2N and Fe3N. Microhardness of the whitelayer does not vary with frequency. The friction coefficient of the samplesvaries between 0.22-0.47 values. Frequency, applied during plasmanitriding, is an important effect on wear rate.2006, 68 pagesKey Words: Pulsed plasma nitriding, design, wear, hardness, diffusioniv