Effects on Al2O3 and La2O3 additions on electrochemical performances of laser‐cladded WC10Co4Cr coatings

Abstract

AbstractAl2O3 and La2O3‐reinforced WC10Co4Cr coatings were fabricated on Cr12MoV steel by laser cladding (LC). The microstructure and phases of obtained coatings were analyzed using a digital microscopic system (DMS) and X‐ray diffraction (XRD), respectively. The effects of Al2O3 and La2O3 mass fractions on the electrochemical corrosion performances of WC10Co4Cr coatings in 3.5% NaCl solution were investigated on an electrochemical workstation. The results show that the WC10Co4Cr with the different Al2O3 mass fractions are composed of Co4W2C, WC, Al2O3, W2C, and Fe‐Cr phases, and the La2O3‐reinforced WC10Co4Cr‐Al2O3 coatings are composed of WC, W2C, Al2O3, La2O3, LaAlO3, and Fe‐Cr phases. The corrosion current density icorrof the substrate, WC10Co4Cr‐Al2O3, and WC10Co4Cr‐Al2O3‐La2O3 coatings decreases from 2.424 × 10−5 to 6.840 × 10−7 A•cm−2; and the corresponding polarization resistance Rp and charge transfer resistance Rct increase from 1371 to 64 536 Ω•cm2 and from 1568 to 14 020 Ω•cm2, respectively. The La2O3‐reinforced WC10Co4Cr‐Al2O3 coatings have higher electrochemical corrosion resistance than the Al2O3‐reinforced WC10Co4Cr coatings, and the WC10Co4Cr‐6%Al2O3‐9%La2O3 coating presents the highest electrochemical corrosion resistance among all the experimental coatings.