Papers by Keyword: Composite Coating

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Authors: Agus Sukarto Wismogroho, Wahyu Bambang Widayatno
Abstract: In this study a new technique for producing an Al/Al2O3 composite coating on a steel substrate by an in situ process was examined. The pre-treating of the steel substrate with Al was carried out by MA at room temperature, followed by MA using a low-energy ball mill at 200-500°C. An Al/Al2O3 coating layer with a homogenous distribution of Al2O3 particles were achieved. The coating layer has not only high hardness but also high fracture toughness.
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: Nor Bahiyah Baba, Mohamad Amir Harunsyam Lamshah, Mohamad Asyraf Mohd Amin
Abstract: The paper discussed on a 3-dimensional porosity network in electroless nickel (Ni) - yttria stabilized zirconia (YSZ) composite coating. The important characteristics of Ni-YSZ composite such as high ceramic YSZ incorporation and adequate porosity up to 40 vol.% are used as the main parameters. The arrangement of the porosity that give a 3-dimensional porosity network within the composite was design in Pro-Engineer Wildfire 3.0 software. Three structures of 3-dimensional porosity network were used namely honeycomb, atomic sphere and rhombic dodecahedra. The calculated area and volume of one unit porosity, consequently the number of porosity were compared between the three structures. These were supported by the porosity in the electroless Ni-YSZ composite coating obtained experimentally. Two batches were produced, EN-YSZ and EN-YSZ-G representing samples without and with pore former respectively. The two batch samples were investigated and compared. The addition of graphite pore former was burnt out completely and left porosity in the coating.
Authors: Wei Qiang Hu, Zong De Liu, Guang Yang, Yong Tian Wang, Hua Lei Zhang
Abstract: A thick Fe-based amorphous and nanocrystalline composite coating was prepared by in-situ tungsten inert gas (TIG) cladding method. The results show that the cladding coating mainly consists of amorphous phase and nanocrystalline grains. The microstructure study shows that the Fe-based composite coatings have unique microstructure including nano-sized grains surrounded by nano-scale amorphous shell layer (encapsulated structure) and the homogeneously distributed dendrites/cellular crystals. The unique microstructure gives rise to the superior micro-hardness and wear resistance of the coating. The Fe-based coatings have great potential as promising wear-resistance structural materials used in electric power and cement industry.
Authors: Shu Fa Chen, Cheng Long Feng, Jin Yang, Jin Song Chen
Abstract: NiCr/Cr3C2-WS2-CaF2 mixed powders were prepared on 1Cr18Ni9Ti stainless steel substrate to fabricate high-temperature self-lubrication wear resistant composite coating by laser cladding. The microstructure of the coating was examined by means of XRD, SEM and EDS. The high-temperature dry sliding friction and wear behavior of the composite coating were evaluated by using a ball-on-block wear tester at room temperature, 300 and 600 , respectively. The results showed that the composite coating had a unique microstructure consisting of γ-(Ni,Fe) solid solution matrix, Cr7C3/WC reinforcement and CrS/WS2 lubricant particles. The hardness of NiCr/Cr3C2-WS2-CaF2 coating by laser cladding was lower than NiCr/Cr3C2 coating, but higher than stainless steel substrate significantly. It was because of the addition of solid lubricant. In the wear process, elevated temperature was helpful to form a lubricating transfer film. As a result, the NiCr/Cr3C2-WS2-CaF2 coating exhibited a notable anti-friction and wear resistance at 300 and 600 .
Authors: Fa Feng Xia, Chun Hua Ma, Yi Fang Yin, Liang Miao
Abstract: Nanocomposite Ni–TiN coatings were prepared by ultrasonic pluse electrodeposition and the effects of ultrasonication on the coatings were studied. X-Ray diffraction analysis was utilized to detect the crystalline and amorphous characteristics of the composite coatings. The surface morphology and metallurgical structure were observed by scanning electron microscopy, high-resolution transmission electron microscopy and scanning probe microscopy. The results show that ultrasonication has great effects on TiN nanoparticles in composite coatings. Moreover, the introduction of ultrasonication and TiN particles led to the formation of smaller nickel grains. The average grain diameter of TiN particles was 33 nm, while Ni grains measured approximately 53 nm.
Authors: Pei Lei Zhang, Zhu Guo Li, Chen Wu Yao, Shun Yao, Feng Gui Lu
Abstract: The Fe32Ni32Si16B18Nb2, Fe31Ni31Si18B18Nb2 and Fe30Ni30Si20B18Nb2, (at. %) alloys are synthesized using low purity of raw materials by high power CO2 laser cladding with synchronous powder feeding. X-ray diffraction results show that the coating has an amorphous structure with some crystalline phases on it. The microstructure of the coatings changes with different amounts of Si. It can be observed that black nanocrystalline grains embedded in the amorphous phase in the TEM image. The coating of Fe31Ni31Si18B18Nb2 alloy was annealed at different temperature for 30 minutes and the microstructure were investigated. The highest Vickers Hardness had exceeded 1300 in the coatings. The amount of Si is a critical factor for fabricating a Fe-Ni based amorphous composite coating.
Authors: Han Jun Wei, Wan Chang Sun, Guan Qun Hou, Feng Zhang, Qin Shi
Abstract: The plating parameters for optimizing the wear and corrosion resistance of Ni-TiC composite coatings were selected by orthogonal test, mainly including the TiC particles concentration, current density, duty cycle, frequency and stirring rate. A three-layer BP (Back Propagation) neural network with Lavenberg-Marquardt algorithm was established by MATLAB, which was used to train the network and predicted orthogonal experimental data. In addition, the best parameters combination of the composite coating were predicted and verified by experiments. The results predicted through the proposed BP model are in good agreement with the experimental values, the relative error is small, and the maximum error is less than 3% and the coefficient of determination value is 0.9997.
Authors: Rui Yan, Hang Wu, S.K. Yu, Shi Ning Ma, Bin Shi Xu
Abstract: Electrochemical corrosion behaviors of two common-used ship coatings——epoxy aluminum coating, chloride rubber iron red coating and their composite coatings immersed in 3.5%NaCl solution were investigated using electrochemical impedance spectroscopy combined with open circuit potential measurements and SEM micrograph analysis. Potential-time result indicates that the free corrosion potential of these three coatings with immersion time are more positive than that of metal substrate, which can serve as barrier layer to protect metal substrate from corrosion. During the course of immersion, increasingly negative shift potentials with time reveal the growth of electrochemical area of anode and corrosion takes place continuously. EIS shows that corrosive species can penetrate into coatings and reach the coating/substrate interface promptly, causing the decrease of its shielding role and the beginning of electrochemical corrosion. SEM micrographs suggest that coatings were compact and continuous compared with obviously coarse and loose after corrosion, indicating the penetration of corrosive species destroys cross linkage of coatings. Composite coatings present better protection performance, displaying the effect of “1+1>2” remarkably.
Authors: Zhong Li Zhang, Qi Shen Wang, Peng Rao Wei, Xue Gong
Abstract: An arc-spraying composite coating system for high-temperature oxidation protection is composed of an inner Fe-Cr-Al alloy layer and an Al-Si alloy outer layer. The high-temperature oxidation behavior of the composite coatings on steel substrate was studied during isothermal exposures in air at 900°C. Experiments show that the coatings on steel substrate are not deteriorated and the substrate is protected well, being exposed to high temperatures up to 900°C. Inter diffusion of alloying elements within the protective coatings occur, while the elements, Cr and Al, are also diffusing to the core of the base metal. As test time proceeds, a large number of chromium oxides are generated in situ within the protective coatings, especially close to the coating/substrate interface. The oxides generated increase the bond strength of the coating to the steel substrate, and together with the surface alumina they provide a long-term effective anti-oxidant protection to steel substrate. The results on titanium sponge production site show that the protective coatings on the reactor have provided an effective protection and prolong the lifetime at least forty percent for the reactors.
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