| Sintered Fe-4 wt.%Ni-1.5 wt.%Cu-0.5 wt.%Mo steels were purse plasma nitrided and the influence of nitriding treatment conditions(temperature, gas mixture, pulse ratio) on the surface layer microstructure the micropore formation behavior and the compound layer properties of the steel has been studied. The pulse ratio was varied from 0.1 to 1, and the temperature and gas ratio(N₂:H₂) were varied from 500℃ to 570℃ and 4:1, 1:1, 1:4, respectively. The number and size of micropore in the compound layer were decreased in a pulsed DC glow discharge by reducing the plasma power and the partial pressure of nitrogen gas. The cross-sectional WDX analysis showed that the penetration depth of nitrogen in sintered steed was 3 times thicker than that of bulk material. |
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