DIFFUSION LAYER GROWTH MECHANISM IN ASPN METHOD USING AN IRON CAGE FOR ST۵۲ STEEL

- The mechanism of diffusion layer growth in plasma nitrided coatings applied on a St۵۲ steel using an active screen is investigated. The nitriding was performed at ۴۵۰,۵۰۰ and ۵۵۰ ◦C temperature nitriding times of ۵, ۱۰ and ۱۵ h, in a gas mixture containing ۲۰ vol. % H۲: ۸۰ vol. % N۲ and DC-pulsed plasma nitriding unit. The surface, cross section and the thickness of diffusion of specimens was studied in terms of optical and scanning electron microscopy. According to the measurements of diffusion layer thickness, values of Q and D۰ for nitrogen diffusion in substrate were calculated as ۵۰۵۸۵ (j/mol) and ۴.۱۱×۱۰-۱۰ (m۲/s)respectively. The variations of depth of hardness during nitriding period was determined

کلیدواژه ها:

plasma nitriding ، A St۵۲ steel ، Diffusion zone ، Growth mechanism