Papers by Keyword: Wide-Band Laser Cladding

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Authors: Qi Bin Liu, Long Jiang Zou, Min Zheng, Chuang Dong
Abstract: In the present paper, bioceramic coating with gradient compositional design was prepared on surface of Ti alloy by using wide-band laser cladding. Effect of rare earth Y2O3 content on gradient bioceramic composite coating was studied. The experimental results indicated that adding rare earth can refine grain. Different contents of rare earth affect formation of HA andβ-TCP in bioceramic coating. With increase of rare earth content, HA andβ-TCP were synthesized. When content of rare earth ranged from 0.4% to 0.6%, the active extent of rare earth in synthesizing HA andβ-TCP got best, which indicated that “monosodium glutamate” effect of rare earth played a dominant role. However, when rare earth content was up to 0.8%, the active extent of rare earth in synthesizing HA and β-TCP conversely went down, which demonstrated that rare earth gradually lost its catalysis in manufacturing HA andβ-TCP.
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Authors: Qi Bin Liu, Ling Wu, Bang Cheng Yang
Abstract: A gradient bioceramic composite coating was prepared by wide-band laser cladding technique on TC4 alloy surface. The influence of rare earths oxide CeO2 on microstructure of bioceramic coating was studied. The experimental results indicated that CeO2 plays an important role in inducing HA + β-TCP formation. There is almost no HA+β-TCP in bioceramic coating without CeO2. When CeO2 content is higher than 0.2 wt.%, the amount of HA+β-TCP catalyzed by CeO2 gradually increases. The amount of HA+β-TCP becomes largest when CeO2 content is up to 0.4wt%. However, when CeO2 content ranges from 0.6 wt.% to 0.8 wt.%, the amount of synthesizing HA+β-TCP conversely goes down. Through cell culture experiment in vitro, the effect of bioceramic coating with different CeO2 contents on the expression of characteristic protein is investigated. The results show that the largest amount of expression of hydroxyproline(Hyp) at 2d and alkaline phosphatase(ALP) at 6d on coating is complied with 0.4wt.% CeO2, The result indicates that bioactivity of bioceramic coating is dependent on the amount of HA + β-TCP catalyzed by different CeO2 contents.
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Authors: Qi Bin Liu, Bang Cheng Yang
Abstract: To eliminate thermal stress during laser cladding and to raise the bonding strength between substrate and coating, composition gradient coatings are designed and fabricated by using wideband laser cladding technique on a Ti alloy. And mechanical properties on coating is studied. The experimental results indicate that the bonding strength between coating and substrate is fairly high, above 38.8MPa. The highest microhardness is obtained for coating containing 0.6wt.% Y2O3 1062HV0.1 and 1405HV0.1, respectively at bioceramic coating and alloyed transition layer. The average tensile strength, bending strength, and elastic modules of coatings are 767.83MPa, 1671.65MPa, and 13.98GPa, respectively.
681
Authors: Qi Bin Liu, Wen Fei Li, Bang Cheng Yang
Abstract: In this study, microstructure and biocompatibility of gradient bioceramic composite coating fabricated by Wide-Band Laser Cladding is investigated. The experimental results indicate that the coating consists of an alloyed transition layer and the bioceramic coating. The bioceramic coating is mainly comprised of HA, CaTiO3, CaO, α-TCP, β-TCP and TiO. The coral-shaped structure and short-rod piled structure existing on the surface of coating. After the implantation of the bioceramic coatings into dogs’ femur for 6, 12, and 24 weeks, hypersusceptibility, rejection and pathological changes are not found. No fiber cyst, necrosis of bone tissue and chronic inflammation obviously appear through slice observation of hard tissues. The bioceramic coating with different ratios of Ca : P have different abilities to induce osteogenesis. At Ca: P=1.4 and 0.6wt.% Y2O3 (No.3 sample), the bioceramic coating is of best bioactivity and biocompatibility.
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Authors: Chun Hua Zhang, Yu Xi Hao, Lin Qi, Fang Hu, Song Zhang, Mao Cai Wang
Abstract: Abstract. The paper presents the results of a study concerned with the surface hardening of Inconel 625 alloys and Ni-base alloy powder on Monel alloy by electro spark deposition and laser cladding processes. The microstructure, the phase composition and the microhardness of samples are investigated by SEM, EDS, XRD and microhardness instrument. It is shown that, the matrix phase is mainly made up of dendritic structure (γ-Ni), interdendritic eutectic phase (Ni3(B,Fe,Si)) and some precipitates (Cr7C3, Cr23C6). Additional, the microhardness of laser cladding layer can be substantially increased, duo to formation of precipitates.
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