Papers by Author: Ding Fan

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Authors: Yao Ning Sun, Ding Fan, Yu Feng Zheng, Min Zheng, Jian Bin Zhang
Abstract: Laser cladding technique was used to form Ni3Si intermetallic composite coating reinforced by in-situ formation NbC particles on Ni-based superalloy substrate. The process parameters were optimized to obtain cladding. The effect of Nb-C addition to the microstructure of the coating was investigated. The morphology of reinforcement particles was discussed. 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 good and free from cracks and pores. The microstructure of the coating was mainly composed of Ni(Si), Ni3(Si, Nb) and NbC. The NbC particles were formed by in-situ reaction between Nb and C during laser cladding process. NbC particles were homogeneously distributed in the composite material. Moreover, the maximum size of NbC particles was more than 4 μm.
1351
Authors: Jian Bin Zhang, Ding Fan, Min Zheng, Yao Ning Sun, Yu Feng Zheng
Abstract: The applications of titanium and titanium alloys under severe wear conditions are highly restricted due to their low hardness and poor tribological properties. To improve the hardness and wear resistance, laser cladding of commercial purity titanium was carried out with a 5 kW continuous wave CO2 laser. WC powders and Ti powders were mixed for cladding in different proportions. The phases of clad layer were characterized by scanning electron microscopy, X-ray diffractometer and energydispersive X-ray spectroscopy. The mechanism of the reaction between melted WC and Ti is discussed.
1316
Authors: Min Zheng, Ding Fan, Jian Bin Zhang, Xiu Kun Li
Abstract: The calcium phosphate bioceramic coating was fabricated on titanium alloy (Ti-6Al-4V) substrate by a 5kW continuous transverse flow CO2 laser. Due to the peculiar role of rare earth oxide in laser cladding, the effect of ceria additive on the microstructure and properties of laser-cladded bioceramic coating was investigated by means of scanning electron microscope (SEM), X-ray diffraction (XRD), microhardness and corrosion resistance testing. The results indicate that the appearance of rare earth oxide ceria in the precursor powders has an impact on the microstructure and properties of the laser-cladded bioceramic coating. Calcium phosphate bioceramic such as hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) are synthesized on the top surface of laser-cladded specimens. And the addition of rare earth oxide ceria in pre-placed powders has an influence on the formation of calcium phosphate bioceramic phases. Furthermore, it reveals that the laser-cladded bioceramic coating of ceria additive in pre-placed powders has more favorable microhardness and corrosion resistance compared with the coating without rare earth oxide.
586
Authors: Yu Feng Zheng, Jian Bin Zhang, Yao Ning Sun, Ding Fan, Min Zheng
Abstract: Three compositions, (Ni75Si25)-5Cr, (Ni75Si25)-10Cr and (Ni75Si25)-15Cr, have been cladded onto Ni-based suaperalloy substrate by pre-placing laser cladding process with a 5 kW continuous wave CO2 laser. Ni75Si25 was also cladded with the same method for comparison. The process parameters have been optimized to obtain defect free claddings. The microstructure and the hardness of the cladded layers were characterized by optical microscopy, scanning electron microscopy, X-ray diffraction and microhardness measurement. The corrosion resistance of the cladded layers was measured in a sulfuric acid solution.
1319
Authors: Min Zheng, Ding Fan, Xiu Kun Li, Qi Bin Liu, Wen Fei Li, Jian Bin Zhang
Abstract: Based on a high power CO2 laser beam passing by pyramid polygon mirror, the bioceramic coatings of gradient composition were fabricated on titanium alloy substrate (Ti-6Al-4V). The relations among laser processing parameters, microstructure and biocompatibility of the gradient bioceramic coatings were investigated. The results indicated that the contents of rare earth oxide additions had an immediate effect on the formation of bioactive phases. The gradient bioceramic coatings showed favorable biocompatibility in vivo after they were implanted into canine femur for 45, 90, and 180 days, respectively. The bioceramic coatings of Ca/P=1.4 and 0.6wt.% Y2O3 totally combined with new bones merely implanted for 45 days. Furthermore, the MTT (Methyl Thiazolyl Tetrazolium) colorimetry results of cell proliferation demonstrated that the cell growth distinctly increased on the gradient bioceramic coatings by laser cladding compared with the un-treated titanium alloy substrate.
1203
Authors: Cheng Xue, Yu Shi, Ding Fan, Hao Zhong, Ming Xiao Shi
Abstract: Dual-bypass MIG welding (DB-GMAW) is a new kind of high speed MIG welding with three arcs. In order to monitor the weld process and control it, a high speed weld system of DB-GMAW was built. The system was run by LabVIEW programs, including getting data of system and control output signals. The test result of system showed that all equipments could be used in the same time. Beside images of weld pool and arc, the weld voltages and currents of every part had been acquired. The signals of bypass current and weld speed also had been input TIG welding sources and worktable motor successfully. Meanwhile, the high speed weld formation had a good quality, and all of these established the closed-loop control of high speed DB-GMAW.
1852
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.
1380
Authors: Ding Fan, Yao Ning Sun, Min Zheng, Jian Bin Zhang, Yu Feng Zheng
Abstract: Laser cladding experiment was carried out with a 5 kW continuous wave CO2 laser by preplacing Ni75Si25 and Ni78Si13Ti9 powders onto Ni-based superalloy substrate. The microstructure of the specimens was monitored by using optical and scanning electron microscopy. The chemical compositions of the alloys and their phases were obtained using X-ray diffraction and energy dispersive x-ray spectroscopy. The phase transformation temperatures were determined by non-isothermal differential scanning calorimetry tests. The microhardness of the laser cladded sample was measured.
1143
Authors: Jian Bin Zhang, Dong Mei Yu, Ze Fen Liang, Ding Fan
Abstract: An approach for fabricating functionally graded specimens of Co-based alloy and molybdenum disilicide (MoSi2) compositions via Selective Laser Cladding (SLD) is presented. The focus aimed at using the functionally graded material (FGM) concept to gradually grade powdered compositions of MoSi2 within a base material of Co-based alloy. A high power CO2 laser was used to process the material compositions to a high density with gradual but discrete changes between layered compositions. The graded specimens initially consisted of 100% Co-based alloy with subsequent layers containing increased volume compositions of MoSi2 (0-80wt.%). Specimens were examined for porosity, phase composition and microstructure. It was found that crack sensitivity of layer can be reduced by adding Co-based alloy into the pure MoSi2 powder.
474
Authors: Ding Fan, Yao Ning Sun, Jian Bin Zhang, Ming Sun
Abstract: Carbides reinforced intermetallic matrix composite coatings for elevated temperature environmental resistance were prepared on Ni-based suaperalloy substrate using CO2 laser cladding process. The phases of clad layer were investigated by scanning electron microscopy (SEM), X-ray diffractometer (XRD) and energy-dispersive spectrometer (EDS). The laser cladding of the Ni78Si13Ti9/WC powder shows that the products mainly consist of TiC, WC and Ni3(Si,Ti) phases. A chemical reaction between WC particle and Ti powder occurs during the laser process, therefore TiC is formed. The microhardness of the samples increases with the increase of the content of WC.
1338
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