Microstructures And Performance Of Plasma Cladding High-chromium Iron-base Wear Resistant Coating By The Precursor Carbonization-composition Process

The sucrose was used as a carbonaceous precursor to prepare composite powders by the precursor carbonization-composition process. And the powders were fused to form a high-chromium iron-base coating on the surface of Q235 steel by means of a reactive plasma cladding process parameter. Metallurgical microscope,SEM and XRD were employed to study compositions and microstructures of the coatings. The microhardness, wear resistance of the coatings were measured on a microhardness instrument and a wear instrument.The experimental result showed that the mixture of the powder and sucrose can be used as raw materials to prepare high quality composite powders by the precursor carbonization-composition process at the temperature of 550℃.With these optimized parameters, the defect-free,4-6mm thickness coatings with ideal shape and good surface quality were formed on Q235 steel by plasma jet surface metallurgy with powder feeding.The coating near the substrate has typical flat epitaxial growth morphology.In the lower part is dendrite and the central part was equiaxed while the surface was spike-like crystal. The white-bright band, appearing between the coating and the substrate, proved metallurgical bond.The results of component analysis showed that:there were primary phase y and substitution solid solution(Cr-Ni-Fe) in the gray black dendritic crystal, and there was eutectic(Cr7C3+Fe3C+γ) in bright white area.The average microhardness of the coating was about HV910, owing to solution hardening and dispersion strengthening.Because of the presence of a large amount of high hardness, wear resistance phase and metallurgically bonding with substrate, the iron-based coatings have excellent wear resistance.The abrasion test results showed that under the wet-sliding wear test condition of room temperature, when the load was 40N, the relative wear resistance of the coatings were 12 times as high as compared with 16Mn steel. When the load is 140N, the relative wear resistance of the coatings were 34 times.