Papers by Keyword: Plasma Spraying

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Authors: You Tao Xie, Xue Bin Zheng, Chuan Xian Ding, Xuan Yong Liu, Yi Zeng, Soo Wohn Lee
Abstract: The in vitro attachment, spread, and proliferation behavior of osteoblast cells on the plasma-sprayed composite coating with 70wt% zirconia and 30wt% dicalcium silicate were studied. The composite coating shows good cytocompatibility. The human osteoblast cells attached, spread and proliferate well on the surface. The cytocompatibility of the coating was attributed to the incongruent dissolution of dicalcium silicate and the large amount of Si-OH functional groups produced on the surface. The released calcium and silicon ions are also positive to the proliferation of cells. All our results show that the composite coating possesses good cytocompatibility.
Authors: Faik N. Oktar, Livia E. Zdrentu, S. Petrescu, Patricia Valério, L.S. Ozyegin, Ismail Peker
Abstract: Hydroxyapatite (HA) material, collected from human tooth, was calcined and then separated very easily to enamel HA (EHA) and dentine HA (DHA). The EHA and DHA were plasma sprayed on pre-prepared titanium implants. HeLa (a lineage malignant fibroblast cell) and primary fibroblast cells cell lines were used in this study. The results using fibroblasts from primary culture are interesting since the cells did not die or became apoptotic. However, this does not mean that the present method reveals the complete biocompatibility of the tested HA material. This study aimed to investigate if fibroblasts with fluorescent tests could be used as a secondary evaluation method for biocompatibity fibroblasts cell culture studies prior to osteoblasts cell culture.
Authors: Nir Ben-Oved, Olivera Kesler
Abstract: A new rapid manufacturing technique for the production of SOFC anodes for direct oxidation of hydrocarbon fuels has been demonstrated. Composite anodes with doped ceria as catalyst and ion conductor and copper as electronic conductor have been fabricated by plasma spraying in air. The process, which can be readily automated and scaled up for mass production, provides a rapid method to produce anodes with mixtures of low and high melting temperature components in several minutes. These anodes previously have required complex multi-step, multi-day processes involving infiltration of sintered pre-forms. This work demonstrates the feasibility of using plasma spray processing to manufacture composite Cu-SDC coatings for application in direct-oxidation SOFC anodes.
Authors: Da Shu Li, Xing Qi Qiu, Zhi Wei Zheng
Abstract: A numerical model using VOF method is developed to describe the phenomenon of a hollow droplet impact on a flat surface including spreading, retardation, recoil and first and secondary break up. The proposed model is verified by literature experiments. Some new hydrodynamic characteristics have been found. The mechanism of central counter jet is explored according to pressure distribution and velocity vectors inside droplet. The relationship between impact features of droplet and deposition parameters is highlighted. In order to investigate the heat transfer rate at the gas-liquid interface, air entrapment and gas cavity are discussed.
Authors: S. Ozsoy, K. Altunatmaz, L.S. Ozyegin, Faik N. Oktar, Tokay Yazıcı, O. Bayrak, Erdem Demirkesen, D. Toykan
Authors: Faik N. Oktar, S. Ozsoy, Lutfiye Sevgi Özyeğin
Authors: Hiroyuki Waki, Akira Kobayashi
Abstract: Thermal barrier coatings (TBCs) have been employed for the insulation of substrates from high temperature in gas turbine plants. The TBC system consists of ceramic top coating, metallic bond coating and substrate. Delamination of the ceramic coating is important problem in TBC systems. In this paper, the delamination mechanism was studied by residual stress history under thermal aging and thermal cycle conditions. In-plane residual stress histories of ceramic coating and bond coating after thermal aging and cycling were measured by X-ray diffraction method. The residual stress under thermal cycling was also calculated by FEM analysis. The results obtained were as follows: (1) in-plane surface residual stresses of the coatings scarcely changed regardless of the increase of thermally grown oxidation (TGO). (2) high compressive thermal stress, residual stress at room temperature, in ceramic coating induced by thermal stress did not occur. It was found that stress of ceramic top coating was relaxed by micro cracks and driving stress of delamination was in-plane high compressive stress.
Authors: Man Tae Kim, Hyup Jae Chung, Gyu Seok Choi, Yong Bae Kim, Kyong Yop Rhee
Abstract: In this study, heat-acupuncture needle was coated with bioceramics by applying a plasma spray coating method to prevent a skin burn in the heat-acupuncture therapy. The effect of coating on the surface roughness of heat-acupuncture needle was investigated and the surface morphology was examined by scanning electron microscope (SEM). The effect of coating on the heat conduction of heat-acupuncture needle was also investigated. The results showed that the surface roughness of uncoated, Al2O3, and ZrO2 coated needle was 0.0675um, 8.568um, and 3.285um, respectively. The surface of ZrO2 coated needle was more uniform than that of Al2O3 coated needle. The results also showed that the heat conduction of heat-acupuncture needle was significantly affected by the bioceramic coating on the needle. Specifically, the maximum temperature of middle part of uncoated, Al2O3, and ZrO2 coated needle was 48°C, 38°C and 42°C, respectively.
Authors: Costel Florea, Costică Bejinariu, Cristian Savin, Bogdan Istrate, Marcelin Benchea, Ramona Cimpoeşu
Abstract: There was obtained superficial layer of ceramic (made of complex oxides 80% yttrium oxide stabilized zirconium ZrO2/8%Y2O3 (Metco 204B-NS) and 20% alumina Al2O3 (Metco 105SFP)) by plasma jet deposition at a temperature of 12000°C of particles, on substrates of iron FC250. The layers were obtained by five successive passages (60 μm thick) on samples with different surface roughness and different processed (0.34, 2.47 și 4.25 μm). For the analysis of the adhesion of ceramic layers to the substrate scratch tests were carried out and the traces analyzed by scanning electron microscopy (SEM 2D and 3D), chemical analysis EDS, and profilometry. In conclusion, it was obtained compact layers on the samples 2 and 3 with micro-cracks on the surface due to thermal gradient that occurs between the layers deposited during the five passes. Regarding the resistance, the sample with the higher roughness (sample 3) resisted most to exfoliation the layer (15 N) in contrast to the sample 2 of 14N and only 10N for the polished sample. It can be concluded that there is a dependency between the surface roughness and the thickness of layer deposited. Scratch marks presents no cracks, pores or adjacent exfoliation. The results show that the technique is suitable for obtaining thin layers of ceramic materials with a very good control of the thickness, very good adhesion to the substrate and a direct relationship between surface roughness and the quality of deposited layer.
Authors: Michel Watremez, T. Renaux, J.D. Guerin, J.P. Bricout
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