Effect of WC content on microstructure, hardness, and wear properties of plasma cladded Fe–Cr–C–WC coating

Abstract

The Q235 sample was coated with ball-milled Fe–Cr–C–WC powder using plasma cladding technology, and the influence of tungsten carbide (WC) content on the surface microstructure, hardness, and wear properties of the coated steel was evaluated. The single factor test of optimal WC content was carried out on DML-02BD plasma cladding machine, and the material after cladding was analyzed. The microstructure distribution, elemental composition and phase composition of the coating were observed by MIRA3-XMH scanning electron microscopy. The microhardness of cladding layer can indirectly reflect the properties of cladding layer to a certain extent, which is measured by the Vickers microhardness tester. The wear quality, friction coefficient and wear mark morphology can directly reflect the wear resistance of the test blocks. These are observed by the ring block friction and wear tester and the ultra depth of field microscope, respectively. With an increasing WC content, the microhardness of the cladding layer shows an upward trend. The main hard phases of the cladding layer after adding WC are (Cr, Fe) _7 C _3 , (Fe, Ni) _23 C _7 , and the other phases are γ -Fe, Fe _3 W _3 C, WCandFe _2 W. After 6 h friction and wear test, the cladding layer with 30%WC showed the best wear resistance. The total wear amount, wear volume, wear rate and friction coefficient were 0.01 g, 4.22 mm ^3 , 2.344 × 10 ^–4 mm ^3 /(N·m), and 0.35, which were 1/10, 1/5, 1/5, and 7/10 of those without WC cladding layer, respectively. It can be concluded that different WC contents affect the surface microstructure and properties of Fe–Cr–C alloy coating treated by plasma cladding technology. At a WC content of 30%, the microstructure and properties of the cladding layer reach the best.

Keywords

• plasma cladding
• Fe–Cr–C alloy
• WC
• microhardness
• wear resistance
• friction coefficient