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An optimized low-temperature chromizing process at 500℃was realized on a plain medium-carbon steel with 0.45 wt pct carbon via a duplex chromizing process which consists of a precursor plasma nitriding,and a followed salt bath thermoreactive deposition and diffusion(TRD)chromizing process.CrN layer with a thin diffusion layer underneath was formed.The duplex chromizing process was studied by optical microscopy (OM),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),X-ray diffraction (XRD),and transmission electron microscopy(TEM).It was found that the chromizing speed at 500℃was successfully enhanced by adding more Cr-Fe powders into the salt bath,and the CrN layer formed at the cost of the prior nitride compound layer.A CrN layer with average 8.1μm in thickness and 1382 HV_(0.01)in microhardness was formed on the substrate by duplex chromizing at 500℃for 24 h.Further more,the CrN layer consisted of nanocrystalline CrN grains.
An optimized low-temperature chromizing process at 500 ° C was realized on a plain medium-carbon steel with 0.45 wt pct carbon via a duplex chromizing process which consists of a precursor plasma nitriding, and a followed salt bath thermoreactive deposition and diffusion (TRD) chromizing The process chrominance layer underneath was formed. The duplex chromizing process was studied by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction , and transmission electron microscopy (TEM) .It was found that the chromizing speed at 500 ° C was successfully enhanced by adding more Cr-Fe powders into the salt bath, and the CrN layer formed at the cost of the prior nitride compound layer. A CrN layer with average 8.1 μm in thickness and 1382 HV_ (0.01) in microhardness was formed on a substrate by duplex chromizing at 500 ° C. for 24 h. More than the first, the CrN layer consisted of nanocrystalline CrN grains.