TiC-Fe-Based Composite Coating Prepared by Self-Propagating High-Temperature Synthesis
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TRODUCTION
TIC-FE-BASED composite materials are widely used as a surface coating to improve the surface properties of metal matrix because of their high specific strength and hardness, high chemical stability, excellent high-temperature resistance, wear resistance, corrosion resistance, and oxidation resistance.[1–4] In general, TiC-Fe-based composite coatings can be prepared by thermal spray[5–10] or laser cladding methods.[11–13] Although the thermal spraying technology is simple and convenient, the obtained coatings are easy to fall off due to the non-metallurgical combination between coating and substrate.[7] The laser cladding method can obtain a good metallurgical bond between coating and substrate, but its application is limited because of the high cost of the laser equipment.[11] In recent years, a new method of self-propagating high-temperature synthesis (SHS) combined with vacuum expendable pattern casting (V-EPC) was attempted to prepare in situ TiC-Fe composite coating on the surface of the metal substrate.[14] The SHS-V-EPC technology has not only the characteristics of low energy consumption and simplicity, but also high bond strength between coating and substrate due to metallurgical combination. SHEN HE and XI’AN FAN are with the The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, P.R. China, and also with the Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081, P.R. China. Contact e-mail: [email protected] QINGMING CHANG and LIXIANG XIAO are with the The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology. Manuscript submitted October 28, 2016. METALLURGICAL AND MATERIALS TRANSACTIONS B
Moreover, the good surface quality and high dimensional accuracy can also be guaranteed due to near-net shape process.[14] It is well known that many factors such as Fe content[15] and Ti/C ratio[16] can affect the microstructure and performance of TiC-Fe composite coatings. It is accepted that the quality of the coating is good when Fe content is about 20 to 40 wt pct. The higher Fe concentration will block the self-propagating reaction and reduce the reaction rate of self-propagating reactions, and the lower Fe concentration will result in poor wettability between TiC particles and Fe matrices. In addition, the high Ti/C atomic ratio can help reduce the particle size of the TiC in situ formed and increase the densification of composite coating. In fact, a good TiC-Fe-based composite coating is closely related to the casting temperature. Unfortunately, the effect of casting temperature on the microstructure and properties of TiC-Fe-based composite coating had not been clearly established. In this work, TiC-Fe-based composite coatings were prepared by SHS-V-EPC technology. The effect of casting temperature on the microstructure of interfaces and the hardness of coatings was investigated in detail. It is worth noting that the
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