The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Chuanxian Ding - One of the best experts on this subject based on the ideXlab platform.
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Plasma-Sprayed Wollastonite Coatings for Biomedical Application
Materials Science Forum, 2005Co-Authors: Xuebin Zheng, Chuanxian DingAbstract:A new bioceramic coating based on Wollastonite was prepared by plasma spraying. The coatings exhibited good mechanical properties. The bond strength of the coating on substrate was about 40 MPa, which is higher than that of HA coatings used in orthopedics and dentistry. The bioactivity of Wollastonite coatings was evaluated in vitro and in vivo. After immersed in simulated body fluid, a bone-like apatite layer was formed on the surface of Wollastonite coatings. Osteoblast could survive and proliferate on the surface of coatings. After implanted in dog’s cortical bone, histological observation demonstrated that bone tissue could extend and grow along the surface of Wollastonite coatings. The coating bonded directly to bone without any fibrous tissue, indicating good biocompatibility and bone conductivity. The Wollastonite coatings also showed good bone inductivity property, inducing new-bone formation on their surface after implanted in marrow. The results obtained indicated that the plasma-sprayed Wollastonite coatings possessed good mechanical properties and excellent bioactivity in vitro and in vivo. It appears that a Wollastonite coating may be suitable for the repair and replacement of living bone, especially for load-bearing situations.
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in vivo evaluation of plasma sprayed Wollastonite coating
Biomaterials, 2005Co-Authors: Xuebin Zheng, Chuanxian DingAbstract:Abstract Wollastonite coatings were prepared by plasma spraying. The bioactivity of Wollastonite coatings was investigated in vivo by implanting in dog's muscle, cortical bone and marrow, respectively. The behaviour of bone tissue around Wollastonite coatings were examined by histological and SEM observation. After 1 month in the muscle, a bone-like apatite layer was found to form on the surface of the Wollastonite coating. When implanted in cortical bone, histological observation demonstrated that bone tissue could extend and grow along the surface of the Wollastonite coating. The coating bonded directly to the bone without any fibrous tissue, indicating good biocompatibility and bone conductivity. SEM and EDS analysis revealed that bone did not bond to Wollastonite coating directly, but through a Ca/P layer. This suggested that the formation of bone-like apatite layer was very important for bonding to the bone tissue. The amount of bone–implant contact was also measured. Wollastonite coating was shown to stimulate more bone formation on its surface than titanium coating after implantation for 1 month, enhancing the short-term osseointegration properties of implant. The test in marrow indicated that Wollastonite coatings could induce new bone formation on their surface showing good bone inductivity property.
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plasma sprayed Wollastonite tio2 composite coatings on titanium alloys
Biomaterials, 2002Co-Authors: Chuanxian DingAbstract:Abstract Wollastonite/TiO2 composite coatings were prepared using plasma spraying technology onto Ti-6Al-4V substrate. The composite coatings exhibit obvious lamellar structure with alternating Wollastonite coating and TiO2 coating. No obvious cracks exist on the interface between coatings and substrate. In the case of composite coatings, the primarily crystalline phases of the coatings are Wollastonite and rutile, indicating Wollastonite and TiO2 did not react during plasma spraying process. Some of rutile in the powders transforms into anatase due to plasma spraying. The mean bond strength of the composite coatings is higher than 30 MPa. The Vickers microhardness of coatings increase with the increase in the content of TiO2. Wollastonite/TiO2 composite coatings were soaked in simulated body fluid to examine their bioactivity. Carbonate-containing hydroxyapatite (CHA) layer was formed on the surface of the Wollastonite and W7T3 coatings soaked in simulated body fluid, while was not formed on the surface of the TiO2 and W3T7 coatings after immersion. In addition, a rich-silica layer appeared at the interface of CHA and Wollastonite and W7T3 coatings. In order to investigate the cytocompatibility of the coatings, osteoblast was seeded onto the surface of the coatings. The scanning electron microscopy observation showed that the addition of Wollastonite promote the proliferation of osteoblast. It is enough to prove that the Wollastonite and Wollastonite/TiO2 composite coatings possess excellent cytocompatibility.
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characterization of plasma sprayed Wollastonite powder and coatings
Surface & Coatings Technology, 2002Co-Authors: Chuanxian DingAbstract:Abstract Spheroidized Wollastonite powder was prepared by plasma spraying natural Wollastonite TC powder into water. The natural and spheroidized Wollastonite powders were deposited onto Ti–6Al–4V substrates using an atmospheric plasma spraying system. The phase composition and microstructure of the powders and coatings were examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The spheroidized powder prepared by plasma spray presented a sphere-like morphology and was composed of crystalline Wollastonite and a little glassy phase. The SEM view of the surface and the cross-section of the coatings revealed that the coating produced with the spheroidized Wollastonite powder possesses a denser structure with fewer microcracks and pores than the coating generated from the natural powder. The tensile adhesion test (TAT) specified by ASTM C-633 was used to measure the tensile bonding strength of the coating. The results indicated that the coating produced with the spheroidized powder is superior to the coating prepared from the natural powder.
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Phase compositions and microstructure of plasma sprayed Wollastonite coating
Surface & Coatings Technology, 2001Co-Authors: Chuanxian DingAbstract:Abstract The phase compositions and microstructure of Wollastonite coatings deposited onto Ti–6Al–4V substrates by plasma spraying were studied using scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The plasma sprayed Wollastonite coating was not homogeneous and had a rough surface. Some pores and microcracks existed in the coatings. The primary crystalline phase in the coating was triclinic Wollastonite. Some crystalline Wollastonite grains had dislocation. The glassy phase was also discovered with some small size crystals in the coating. In addition, tridymite (SiO2) and CaO were also found in the coating.
Moncef L Nehdi - One of the best experts on this subject based on the ideXlab platform.
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effects of shrinkage reducing admixture and Wollastonite microfiber on early age behavior of ultra high performance concrete
Cement & Concrete Composites, 2014Co-Authors: Ahmed M Soliman, Moncef L NehdiAbstract:Abstract In this study, the effect of incorporating shrinkage reducing admixtures (SRA) and/or Wollastonite microfibers on the early-age shrinkage behavior and cracking potential of ultra-high performance concrete (UHPC) was explored. Wollastonite microfibers were added at rates of 0%, 4% and 12% as partial volume replacement for cement, while SRA was added at 1% and 2% by cement weight. Results show that the reinforcing effect induced by Wollastonite microfibers mitigated the reduction in compressive strength induced by SRA. Addition of Wollastonite microfibers to SRA mixtures did not impart a significant change in the measured free shrinkage strain, while it enhanced the cracking resistance compared to that of mixtures incorporating SRA alone. Moreover, adding Wollastonite microfibers reduced the leaching of SRA from concrete under submerged conditions, thus leading to higher efficiency of SRA in reducing shrinkage. Partially replacing cement with natural Wollastonite microfibers also leads to a reduction in the cement factor, which represents economic and environmental benefits.
P Thavorniti - One of the best experts on this subject based on the ideXlab platform.
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microwave synthesis of Wollastonite powder from eggshells
Journal of The European Ceramic Society, 2011Co-Authors: S Vichaphund, M Kitiwan, Duangduen Atong, P ThavornitiAbstract:Abstract Wollastonite powder was synthesized by microwave assisted solid-state reaction in a 2.45 GHz microwave furnace with a maximum power output of 2.4 kW. Bio-solid waste eggshell and SiO 2 were used as starting materials for the synthesis. α-Wollastonite formation started at 800 °C. The single phase was obtained after 10 min heating at 1100 °C. The use of microwave heating lowered the processing temperature and time for Wollastonite synthesis.
Barzin Mobasher - One of the best experts on this subject based on the ideXlab platform.
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mechanical properties of micro and sub micron Wollastonite fibers in cementitious composites
Construction and Building Materials, 2015Co-Authors: Robert Kachala, A Bonakdar, Barzin MobasherAbstract:Abstract Effect of mineral Wollastonite micro and sub-micron fibers on the mechanical properties of cement-based systems are studied using compressive strength and notched beam flexural tests. A series of blended paste and mortar mixtures with silica fume and Wollastonite particles of different morphology and size were developed and tested. Testing variables included four grades of Wollastonite fibers or platelets with average particle size ranging from 33 to 2000 μm, with aspect ratios varying from 3:1 to 20:1, and cement replacement levels of 5%, 10%, and 15%, by mass. Non-linear fracture mechanics concepts used indicate considerable effect of Wollastonite reinforcement on the fracture resistance of the cementitious matrix. Uniaxial compressive strength tests showed a 30% increase due to 10% cement replacement with Wollastonite and silica fume. Flexural strength was enhanced by 40% and fracture toughness by as much as 150% at the optimal dosage of Wollastonite fibers. Morphology of fractured surfaces was studied using SEM to correlate the mechanical properties with internal micro-structure. It was observed that at optimal dosage, Wollastonite fibers promote classical toughening mechanisms such as crack bridging and crack path deflection.
Ahmed M Soliman - One of the best experts on this subject based on the ideXlab platform.
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effects of shrinkage reducing admixture and Wollastonite microfiber on early age behavior of ultra high performance concrete
Cement & Concrete Composites, 2014Co-Authors: Ahmed M Soliman, Moncef L NehdiAbstract:Abstract In this study, the effect of incorporating shrinkage reducing admixtures (SRA) and/or Wollastonite microfibers on the early-age shrinkage behavior and cracking potential of ultra-high performance concrete (UHPC) was explored. Wollastonite microfibers were added at rates of 0%, 4% and 12% as partial volume replacement for cement, while SRA was added at 1% and 2% by cement weight. Results show that the reinforcing effect induced by Wollastonite microfibers mitigated the reduction in compressive strength induced by SRA. Addition of Wollastonite microfibers to SRA mixtures did not impart a significant change in the measured free shrinkage strain, while it enhanced the cracking resistance compared to that of mixtures incorporating SRA alone. Moreover, adding Wollastonite microfibers reduced the leaching of SRA from concrete under submerged conditions, thus leading to higher efficiency of SRA in reducing shrinkage. Partially replacing cement with natural Wollastonite microfibers also leads to a reduction in the cement factor, which represents economic and environmental benefits.