Fe-coating-mediated carburization: A new strategy for fabricating a tungsten carbide coating on tungsten

Abstract

A tungsten carbide (WC) ceramic coating is fabricated by a new method of Fe-coating-mediated carburization, in which the tungsten substrate is carburized using a pre-electroplated Fe coating. In this carburization process, the electroplated Fe coating is transformed into a carbon steel coating, and a significant number of interstitial carbon atoms in the carbon steel coating diffuse into the tungsten substrate, forming a WC ceramic coating on it. The so-formed WC ceramic coating is nonporous, uniform in thickness, and has a microstructure with grain size gradient. The thickness of the electroplating Fe coating had no effect on the microstructure and growth rate of WC coating when the thickness of the electroplating iron coating was in the range of 5–20 μm. The hardness of the coating reached 2800 HV0.05, and the adhesion strength between the substrate and coating was greater than 100 N. Compared with conventional solid carburization, Fe-coating-mediated carburization can generate nonporous ceramic coatings over wider ranges of temperature and carbon potential at a higher growth rate. Accordingly, the microstructure and properties of the coating could be optimized further.

Keywords

• Carburization
• Electroplating
• Ceramic coating
• Surface hardening
• Refractory metal