Papers by Author: Jing Jie Dai

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Authors: Ding Fan, Jian Bin Zhang, Yao Ning Sun, Jing Jie Dai, Rui Fu
Abstract: Laser cladding technique was used to form Ni3(Si,Ti) intermetallic composite coating reinforced by in-situ formation TiC particles on Ni-based superalloy substrate. The experimental results showed that an excellent bonding between the coating and the substrate was ensured by a strong metallurgical interface. The clad coating was very well and free from cracks and pores. By means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD), the effect of Ti-C addition to the microstructure and microhardness of the coating was investigated. The microstructure of the coating was mainly composed of Ni(Si), Ni3(Si,Ti) and TiC. The average microhardness of the coating was improved with increasing the Ti-C content. The microhardness was up to 780Hv when Ti-C addition was 20 wt. pct, which was much greater than that of Ni-based superalloy substrate.
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Authors: Jian Bin Zhang, Ding Fan, Jing Jie Dai, Yao Ning Sun
Abstract: Laser surface alloying is an attractive processing to improve surface hardness, wear and corrosion resistance. In this paper, a continuous wave CO2 laser was used to irradiate commercially pure titanium surface with pre-placed active carbon powders in argon atmosphere. A compact, well-adherent, and crack-free TiC/Ti composite layer was obtained. The microstructure and phase constitution of the alloyed layers were determined and analyzed, and the micro-hardness was measured. The result of X ray diffraction (XRD) analysis shows that the alloyed layers contain TiC and Ti (martensite). The scanning electron microscopy (SEM) observation shows TiC growth morphologies have a well-developed dendrite, cellular dendrite, globular microstructure and cross-petal microstructure. The mechanism of the formation of titanium carbides is discussed. Micro-hardness of the laser surface alloyed layer was improved to 420 Hv as compared to 200 Hv of the as-received commercially pure titanium.
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