A layer of carbide with an ultra-high hardness was formed on the surface of steel through means of immersing the steel in a borax bath containing carbide forming elements. Producing a thin layer of carbide by this method ; however, took a relatively long time. Besides, a de-carburized zone situated just beneath the layer of carbide generally was observed to be present, which consequently led to a poor adhesion between the carbide and steel matrix. An effective method employed for eliminating the two problems has been proposed in this work, i.e., carburizing the steel before immersion in the borax bath. S10C, S50C and S105C were used as steel samples. The borax bath was given an addition of 10% ferro-vanadium powder by weight. The benefits of pre-carburization were evaluated from (a) carbon distribution, hardness distribution and microstructure in the outer layer of steel samples, (b) wear resistance and X-ray diffraction pattern on the surface of steel, and (c) time required to obtain a specific thickness of carbide at a given temperature.
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