Papers by Keyword: Oxidation Resistance

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Authors: Jing Wang, Yi Chao Ding, Hong Cheng, Yi San Wang
Abstract: TiC particulates reinforced iron matrix surface composite was produced by cast technique and in-situ synthesis technique. The surface composite was investigated from thermodynamics, microstructure, wear-resistance and oxidation-resistance. The results show TiC particles whose volume fraction is about 40% exhibit fine size in iron matrix on the surface composite. An excellent metallurgy-bond is observed between the surface composite and the gray iron. Fe-TiC surface composite shows good oxidation-resistance at 900°C and great wear-resistance under condition of dry sliding.
Authors: Zi Bo He, He Jun Li, Xiao Hong Shi
Abstract: In order to improve the anti-oxidation of C/C composites, a C/SiC functionally graded coating for C/C composites was prepared by low pressure chemical vapor deposition (LPCVD) using methyltrichlorosilane (MTS, CH3SiCl3) and H2 as precursors. The relative amount of C and SiC in coatings was varied by controlling the input ratio of H2 to MTS. The phase composition and morphology were examined by scanning electron microscope (SEM) and X-ray diffraction (XRD), and the content distribution of C and SiC phases were investigated by energy dispersive spectroscopy (EDS). The isothermal oxidation test was evaluated at 900 °C and 1500 °C respectively. The results showed that the as-obtained coatings were possessed of a dense and uniform structure, and the SiC content in coatings increased with an increment of the molar ratio of H2 to MTS. The C/SiC coating had a good oxidation resistance.
Authors: F. Lamouroux, Sebastien Bertrand, R. Pailler, Roger R. Naslain
Authors: Long Gang Wan, Zhi Gang Huang, Shao Rong Song, Jia Ping Wang, Jie Li
Abstract: Based on SiC aggregate, SiC powder and ultra-fine SiC powder as the main starting materials and B4C as additive, the newly-developed self-bonded SiC material was pressed and fired at 2200°C for 10 hours in Ar environment in the high-temperature furnace. The phase composition and microstructure were investigated. In the paper, traditional self-bonded SiC material and Si3N4-bonded SiC material were taken for comparison with the newly-developed self-bonded SiC material in terms of strength, thermal conductivity, cryolite resistance, molten alkali resistance and oxidation resistance etc. The results show that the newly-developed self-bonded SiC material contains 98.42% α-SiC and presents obvious higher thermal conductivity than traditional self-bonded SiC material and much better cryolite resistance, molten alkali resistance and oxidation resistance than traditional self-bonded SiC and Si3N4-bonded SiC materials.
Authors: Chun Xiang Gao
Abstract: A very effective approach to improve the oxidation resistance of Ti-6Al-4V alloy was proposed. The Ti-6Al-4V alloy was firstly phosphated and then coated by silica using sol-gel dip-coating technique. A duplex layer of TiP2O7 and amorphous silica was synthesized at the alloy surface. The isothermal and cyclic oxidation behavior of the treated alloy with silica coating and the corresponding bare alloy was investigated at 600 oC in static air to investigate the synergetic effect of phosphorization and amorphous SiO2 coating on the oxidation resistance of the alloy. The isothermal and cyclic oxidation resistances of the alloy were greatly improved.
Authors: Bożena Szczucka-Lasota, Krzysztof Szymański
Abstract: The material conception of manufacture new coatings with high dispersion phases are presented. The coatings were obtained by thermally sprayed technology. The results of the hot temperature oxidation test of the new elaborated coatings were analyzed and compared. The reaction rate constant was calculated. The mass chance as a function of spallation process were recorded The microstructure of coatings was obtained by LM microscopy. After corrosion tests, the presented coatings were investigated in respect of the changes on the surface like: pits, cracks as well as oxidation layers. The results have been stored using digital imaging techniques, Nikon and PC. The presented coatings can be used to basic protection to wear and corrosion condition in the energy boiler.
Authors: Tian Quan Liang, Xian Fang Yang, Yi Li Wang, Cui Hua Zhao
Abstract: The characterization in microstructure, morphology and oxidation behavior of three iron-based coatings by Supersonic Arc Spraying (HVAS), were investigated by XRD, FESEM, EDS and thermal exposure in furnace in this paper. It is indicated that the three coatings are typical layer and compact structure. The coatings are composed of Fe (s.s) phase and kinds of ferric oxides, chrome carbides and/ or intermetallic phase distributing along the interface of lamellar layers. More Cr and Ti, Al elements can alternate the diameter and morphologies of the holes, resulting from the formation of oxides, carbides and intermetallic phase. The results indicate that SXTiAlC coating shows the most excellent oxidation resistance with 2.70 mg·cm-2 in mass gain, while that are 88.08 mg·cm-2 and 16.64 mg·cm-2 after 100 h thermal exposure at 800°C for LX88A and SXHCrA coatings, respectively. The oxidation behavior is discussed.
Authors: Wan Chang Sun, Ming Feng Tan, Jian Hua Lu, Lei Zhang, Quan Zhou
Abstract: Electroless Ni-P and Ni-P-Al2O3 composite coatings on low carbon steel (Q235) sheets were prepared by adopting optimum plating process. The cross-section morphology and structure as well as the phase transformation of the composite coatings were studied by scanning electron microscopy(SEM), X-ray diffraction(XRD). It was shown that the Al2O3 particles homogeneously dispersed in the entire Ni-P film matrix, and the structure of Ni-P-Al2O3 composite coatings as deposited was amorphous. The corrosion behaviors were evaluated by electrochemical tests. The experimental results indicated that the corrosion resistance of Ni-P-Al2O3 coatings was superior to Ni-P coatings due to the effect of Al2O3 particles. In addition, the oxidation resistance test, which was carried out by using oxidation weight method, showed that ternary Ni-P-Al2O3 composite coating had a better oxidation resistance than Ni-P coating.
Authors: E. Fénard, J.L. Besson, Martine Desmaison-Brut
Authors: Shigeru Okada, Kunio Kudou, T. Mori, Takaaki Shishido, I. Higashi, Naoki Kamegashira, Kazuo Nakajima, T. Lundström
Abstract: Single crystals of AlMgB 14 and AlMgB 22 were grown from a high-temperature aluminum metal flux in an Ar atmosphere. The optimum conditions for growing AlMgB 22 and AlMgB 14 were established using the starting mixtures of B/Mg=0.5-1.0 and B/Mg=2.0-6.0. The AlMgB 14 and AlMgB 22 crystals obtained have well-developed {001} and {100} faces, and were black with a metallic luster. The maximum dimensions of these crystals were about 5.2 mm and 4.6 mm, respectively. The values of micro-Vickers hardness of the AlMgB 14 and AlMgB 22 crystals are in the ranges of 23.9±0.6-27.6±0.6 GPa. The oxidation process of AlMgB 14 and AlMgB 22 crystals were studied up to 1473 K by TG-DTA method. The susceptibility of AlMgB14 with an increase at low temperatures does not show any particular features, being indicative of a paramagnetic contribution, which is likely due to impurities. The susceptibility of the AlMgB 22 sample shows no apparent contribution from impurities and also does not have any anomalous behavior.
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