Papers by Author: Yao Ning Sun

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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: 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: Qing Yu, Yao Ning Sun, Wen Lei Sun
Abstract: Laser cladding technique was used to form Ni3Si intermetallic coating by Ti addition on Ni-based superalloy substrate. The coating was investigated by optical microscopy and X-ray diffraction (XRD). The clad coating was dense, compact and smooth. An excellent bonding between the coating and the substrate was ensured by a strong metallurgical interface. The laser clad Ni3Si-Ti intermetallic coating has a rapidly solidified microstructure consisting of Ni (Si), Ni3Si (L12) and Ni31Si12 . The grain refinement effect has been achieved due to the occurrence of Ti in cladding layers. By increasing the proportion of Ti, the hardness decreased as the Ti content increasing, the peaks intensity of Ni31Si12 decreased.
123
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: Yao Ning Sun, Wen Lei Sun, Xu Dong Zhang, Qing Yu, Xin Mei Li
Abstract: Using laser cladding technique, Ni3(Si Ti) matrix composite coatings reinforced by in-situ synthesis (Ti,W)C multi-ceramics were fabricatcd by preplacing Ni78Si13Ti9( at%)powders containing different WC contents on the nickel-matrix superalloy substrate. The phases of coatings were investigated by scanning electron microscopy (SEM), X-ray diffractometer (XRD) and electron probe microanalysis (EPMA). Phases of the coatings mainly composed of Ni3(Si Ti), (Ti,W)C multi-ceramics A chemical reaction between WC particle and Ti powder occurs during the laser process, therefore (Ti,W)C was formed.
929
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
Authors: Jian Bin Zhang, Ding Fan, Yao Ning Sun, Yu Feng Zheng
Abstract: Surface modification is a promising technique to improve wear properties of titanium and titanium alloys by modifying either the surface composition or microstructure. Laser remelting and laser nitriding of commercial purity titanium were carried out under pure argon and pure nitrogen ambient, respectively. Characterization of the laser treated surface was done by optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), microhardness tester. During laser irradiation heating, Ti exhibits a height activity and combines with N in the atmosphere of pure nitrogen forming TiN and TiN0.3, whereas Ti only transform into martensitic Ti in pure argon. The Vickers microhardnesses are greatly improved by laser remelting and laser nitriding.
1745
Authors: Yao Ning Sun, Ding Fan, Ming Sun, Yu Feng Zheng, Jian Bin Zhang
Abstract: Laser cladding technique was used to form Ni3(Si,Ti) intermetallic coating by Nb addition on Ni-based superalloy substrate. The coating was investigated by optical microscopy and X-ray diffraction (XRD). The clad coating was dense, compact and smooth. An excellent bonding between the coating and the substrate was ensured by a strong metallurgical interface. Ni3(Si,Ti) phase was detected in all of the claddings, and NbNi3, Nb3Ni2Si were detected in Nb additional experiments. The peaks intensity of Nb3Ni2Si and NbNi3 increased with the increasing of Nb content. The Ni3Nb and Nb3Ni2Si were formed when Nb was beyond its solubility in the L12 Ni3(Si,Ti). The average microhardness of the coating was improved with the increasing of the Nb content. The microhardness was up to 530Hv when the atom percentage of Nb addition reached 5%, and it was much greater than that of Ni-based superalloy substrate.
1716
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