Study On The TiCN Coating Prepared By Reactive Plasma Spraying And Its Electrochemical Properties

In this paper,reactive plasma spraying technology was used for preparing TiCN coatings.However,there are some defects in the coating,such as pores,cracks,due to the characteristics of the technique,which excellent performance can not be fully utilized.In this research,TiCN coatings were prepared using Ti powder and graphite.Then the coatings were modified by oxidation treatment,nitriding and addition of Cr element.The phase composition,microstructure were analyzed by SEM,XRD,and XPS,the electrochemical corrosion property was evaluated as well.The results show that:After oxidation treatment at 400?and 600?,the main phases were TiC_0.7N_0.3and TiC_0.8N_0.2.The oxide content increased and the new phase TiO₂ was detected after oxidation treatment at 600?.After oxidation treatment at 800?,coating oxidized seriously,more oxide were detected.The porosity decreased with the increase of the oxidation temperature,the minimum value?5.25%?was obtained after oxidation treatment at 600?.The corrosion resistance of the coating was improved after oxidation treatment.The E_corrorr first increased and then decreased with the increasing oxidation temperature,The maximum value was obtained after oxidation treatment at600?,which was-598mv.Under the same conditions,the minimum value of I_corrorr was obtained,which was 5.86 uA?cm^-2.After nitriding,the dense nitrogen-rich layer was formed on the surface,and the porosity decreased from 8.64%to 7.86%.The E_corr of the nitride TiCN coating increased to-602mv,the growth rate was 13%compared to the TiCN coating.The I_corr of the nitride TiCN coating decreased to 8.62 uA?cm^-2,which reduced by 44%.The incorporation of Cr did not change the microstructure of the coating.The coating consisted of TiC_0.7N_0.3,Cr0.₅Ti_0.5N,and metallic Cr.The porosity of the coating decreased with the increasing of the Cr content,the minimum value is 5.19%,which is obtained when the addition of Cr is 20wt%.The E_corr of the coating first increased and then decreased with the increase of Cr content.The maximum value was obtained when the addition of Cr is 20wt%,which was-465mv.Under the same conditions,the minimum value of I_corr was obtained,which was 3.42 uA?cm^-2.TiCN coating after different processes treatment,the?TiCr?CN composite coating showed the best corrosion resistance,and the nitriding treatment was the worst.The corrosion mechanism of the coating after oxidation treatment and nitriding treatment as same as the TiCN coating.Corrosion reaction of Cr in the?TiCr?CN composite coating occurs first,and then the substrate is etched.