Study on laser in-situ synthesized TiC-TiB2/Fe composite coating and its oxidation resistance
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摘要: 为了提高材料的高温抗氧化性,采用激光原位合成的方法制备了TiC-TiB2/Fe复合涂层,并进行了理论分析和实验验证,取得了复合涂层的相组成、显微组织及抗氧化性能数据。结果表明,涂层物相主要由-Fe,TiC,TiB2和 (Fe,Cr)7C3等组成,细小的方块状TiC颗粒和长条状TiB2均匀弥散分布于涂层基体上。经600℃恒温氧化60h后,TiC-TiB2/Fe复合涂层表面形成了连续致密的氧化膜,其主要由细小的Fe2O3,FeCr2O4,(Cr,Fe)2O3、金红石型TiO2以及Al2O3等球状颗粒组成,颗粒排列紧密,各氧化物形成热力学条件是满足的。复合涂层在600℃的恒温氧化动力学曲线呈抛物线型,在最初的10h内氧化增重速度较快,之后曲线趋于平缓。60h后其增重仅为0.75mg/cm2,抗氧化性能约是半钢的15倍。此研究结果对提高材料高温抗氧化性有一定的指导意义。Abstract: In order to improve the high-temperature oxidation resistance of materials, TiC-TiB2/Fe composite coating was in-situ synthesized by laser cladding. The data of phase, microstructure and oxidation resistance of composite coating were obtained after theoretical analysis and experimental verification. The results indicate that the phases of composite coating are mainly composed of -Fe, TiC, TiB2 and (Fe,Cr)7C3 etc. The fine block-shaped TiC particles and strip-shaped TiB2 disperse on the coating substrate uniformly. The continuous and compact oxidation film is formed on the surface of TiC-TiB2/Fe composite coating after being oxidized isothermally at 600℃ for 60h. The oxidation film consists of fine and spherical oxides such as Fe2O3, FeCr2O4, (Cr,Fe)2O3, rutile TiO2 and Al2O3 and so on, arranged closely. Thermodynamic conditions of oxide formation are satisfied. The oxidation kinetic curve of composite coating at constant temperature of 600℃ is parabolic. The rate of oxidation weight gain is much higher during the initial 10h, and then becomes slower gradually. The oxidation weight gain is 0.75mg/cm2 after being oxidized for 60h. The oxidation resistance of composite coating is 15 times higher than that of semi-steel. The results have some guiding significance to improve the high-temperature oxidation resistance of materials.
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Keywords:
- laser technique /
- composite coating /
- in-situ synthesis /
- oxidation resistance
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