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      20 August 2013, Volume 0 Issue 8 Previous Issue    Next Issue
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    State-of-the-art of Cold Spraying Composite Coatings
    LI Wen-ya, HUANG Chun-jie, YU Min, LIAO Han-lin
    2013, 0 (8): 1-10.   DOI: 10.3969/j.issn.1001-4381.2013.08.001
    Abstract ( 1052 ( PDF (1147KB)( 390 Citation
    Based on the fact that cold spraying (CS) was increasingly attracting more and more attention from researchers worldwide, this paper made detailed summarization and discussion on fabricating composite coatings via CS according to the published literature. Firstly, the powder preparation methods prior to spraying and the effects of processing parameters on deposition of composite coatings were explored. And then, the fabrication of metal-metal, metal-ceramic, metal-intermetallics and nano-composite coatings were summarized. Eventually, the present problems and potential applications existing in composite coatings fabricated by CS were discussed.
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    Effects of Compound Molten Salt on Undercooling of GH4169 Superalloy
    PENG Zi-chao, XIE Fa-qin, WU Xiang-qing, ZHANG Jun
    2013, 0 (8): 11-15.   DOI: 10.3969/j.issn.1001-4381.2013.08.002
    Abstract ( 566 ( PDF (1997KB)( 171 Citation
    The method of molten salt denucleating was applied to study the rapid solidification of GH4169 superalloy. The best compound molten salt and process parameters were gained through orthogonal experiment, then the maximum undercooling, 250K, of GH4169 superalloy was achieved, at the same time, the mechanisms of molten salt and process parameters were also investigated; the solidification morphologies of the undercooled IN718 superalloy were found to be dependent on the degree of undercooling. Through observed the microstructures of GH4169 superalloy with variable undercooling, the solidification microstructure of IN718 underwent two grain refinement, which was transferred from dendrite structure to granular grain. When the undercooling achieved 250K, the average grain size was only 5.5μm.
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    Tribological Behavior of Plasma Sprayed MoS2/Cu Composite Coating Under Vacuum Atmosphere
    ZHEN Wen-zhu, LIANG Bo
    2013, 0 (8): 16-22.   DOI: 10.3969/j.issn.1001-4381.2013.08.003
    Abstract ( 727 ( PDF (3805KB)( 432 Citation
    MoS2/Cu composite coating was deposited by air plasma spraying on 2A12 aluminum alloy substrate using MoS2/Cu composite powder as raw material. Microstructure and wear surface of coating were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and Raman spectra. The tribological properties of as-sprayed coating in vacuum were explored using GTM-3E ball-on-disc vacuum friction and wear instrument. The results showed that MoS2 particles were homogeneously distributed in the as-sprayed coating. The as-sprayed coating was dense and had good bonding with aluminum matrix. XRD analysis demonstrated that Cu, MoS2 and Cu2O phase were observed. Under the test conditions, the as-sprayed coating exhibited excellent friction reducing effect through the addition of MoS2 component, the obtained friction coefficients were in the range from 0.05 to 0.15. The low friction coefficient could be attributed to the formation of uniform MoS2 lubricating transfer film. The main wear mechanisms observed in vacuum were fatigue wear and brittle fracture.
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    Dry-sliding Tribological Characteristics of CuZn Self-matched Pairs Under Interfering of Magnetic Field
    WEI Yong-hui, ZHANG Yong-zhen, CHEN Yue
    2013, (8): 23-27.   DOI: 10.3969/j.issn.1001-4381.2013.08.004
    Abstract ( 714 ( PDF (1787KB)( 253 Citation
    The dry-sliding tribological characteristics and interfering mechanism of magnetic field of CuZn self-matched pairs were studied by use of improved MPV-1500 type friction and wear tester at room temperature. The results show that, with the magnetic field exerting and increasing, the roughness of friction surface increases and oxygen content of friction surface reduces; the main oxides are Cu64O. Along with magnetic field intensity increasing, both wear rate of CuZn pins and average friction coefficient of friction pairs has enlarging tendency, that is, magnetic field aggravates the friction and wear of CuZn. Additions to ferromagnetic materials on the back of diamagnetic materials can overcome the adverse effects of magnetic field on tribological properties. Each of selecting and matching of friction pairs materials, relative size of friction surface and magnetism of clamping device can affect the results of tribological examination.
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    Thermal Cyclic Oxidation Behavior Between NiCoCrAlYHf Bond Coat and a Kind of Ni-based Single Crystal Superalloy
    ZHONG Jin-yan, MU Ren-de, HE Ying, HE Li-min
    2013, (8): 28-35.   DOI: 10.3969/j.issn.1001-4381.2013.08.005
    Abstract ( 826 ( PDF (3926KB)( 209 Citation
    A metallic protective coating on the third generation single crystal superalloy was investigated. The coating surface, interface morphology and phase structure of the organization were characterized by scanning electron microscopy(SEM),energy dispersion X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Interdiffusion behavior of coatings and cyclic oxidation kinetics were analyzed. A single NiCoCrAlYHf coating was deposited onto the single crystal superalloy by arc ion plating (AIP). The results showed that an interdiffusion zone (IDZ) were formed in Ni-based single crystal superalloy after 600h heat treatment at 1100℃ in the atmospheric environment.The elemental interdiffusion between the coating and the substrate occured as Al diffuse inward from the coating to the substrate and Cr diffuse outward from the substrate to the coating. There were amounts of topologically close-packed phases (TCP) precipitated under coating 60μm in the superalloy and ultimately came into being secondary reaction zone (SRZ).
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    Effect of Ni,Mo and Cu Addition on Microstructure and CO2 Corrosion Resistance of 13Cr Stainless Steel
    ZHANG Xu-yun, GAO Ming-hao, XU Zi-yi, WANG Yong, BI Feng-qin
    2013, (8): 36-41,49.   DOI: 10.3969/j.issn.1001-4381.2013.08.006
    Abstract ( 842 ( PDF (2931KB)( 293 Citation
    The special 13Cr stainless steel containing different contents of Ni, Mo and Cu was melted by plasma arc furnace using orthogonal experimental method. The microstructure, phase characteristics, electrochemical corrosion, high-temperature and high-pressure immersion corrosion behavior in the oilfield produced solution saturated with CO2 of alloys were investigated. The results indicated that the microstructure of alloy was mainly of martensite and ferrite, which was slightly different with the contents of Ni, Mo and Cu. Ni4Mo1.2Cu1.4 alloy exhibited the highest hardness (296.48HV1.0) for the occurrence of high content of martensite. All alloys exhibited the remarkable nature of the passivation effect. The lowest passivation current density 2.99×10-6A·cm-2 and highest pitting potential 0.35V (SCE) were found in Ni4Mo1.2Cu1.4 alloy resulted from the stable passive film. The general corrosion rate of alloys at high temperature and high pressure ranged from 0.041mm/a to 0.053mm/a, was lower than the given value 0.076mm/a. An increased in Ni, Mo and Cu content enhanced corrosion potential leading to the reduction of corrosion tendency. The most effective element for improved the corrosion resistance of alloys was Cu.
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    Relationship Between Residual Plastic Deformation and Metal Magnetic Memory Signals of Specimens
    BAI Yong, XU Fan, QIAO Ai-tong
    2013, (8): 42-49.   DOI: 10.3969/j.issn.1001-4381.2013.08.007
    Abstract ( 611 ( PDF (10914KB)( 142 Citation
    Tensile tests on notched specimens were operated to study the magnetic memory effect of Q235 steel, and magnetic signals along the scan lines were recorded after unloading. Combined with results of finite element analysis, the connection between stress concentration situation and magnetic signals in the elastic deformation state was studied; the connection between residual plastic strain and magnetic signals in the plastic deformation state was studied. The results showed that magnetic signal had strong relation with the stress concentration situation and elastic deformation state. Magnetic signals can be used to determine positions and dimensions of defects, and study the distribution of plastic deformation.
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    Failure Analysis of Air Compressor Blade
    YOU Yi-liang, DONG Jian, ZHANG Zheng, ZHONG Qun-peng
    2013, (8): 50-54.   DOI: 10.3969/j.issn.1001-4381.2013.08.008
    Abstract ( 808 ( PDF (3261KB)( 154 Citation
    The macro and micro feature of failure blade, chemical composition of fracture surface, metallography and hardness were analyzed by SEM,EDS and optical microscope. The results revealed that lower hardness of failure blade resulted in decreased resistance to high cycle fatigue properties. The fatigue crack which caused final rupture initiated from the inclusion near surface.
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    Synthesis and Bonding Properties of Reactive Hot Melt Polyurethane Adhesives
    TANG Qi-heng, HE Ji-yu, AI Qing-song, YANG Rong-jie
    2013, (8): 55-59.   DOI: 10.3969/j.issn.1001-4381.2013.08.009
    Abstract ( 1103 ( PDF (1631KB)( 375 Citation
    One kind of heat resistant and high bonding strength of reactive hot melt polyurethane adhesive (RHMPA) was successfully synthesized using a two-step bulk polymerization with 4,4'-diphenlymethane diisocyanate (MDI), poly(tetramethylene glycol) (PTMG), and 1,4-butanediol (1,4-BDO). The effect of RHMPA chain extended at different time and temperatures on adhesive performance was studied by single lap shear strength and tensile strength of butt joints. The results showed that the bonding strength increased with the chain extending reaction time and temperature.Moreover,the higher the reaction temperature,the increasing trend of butt bond strength was more obvious.In addition,the influence on adhesive performance of the RHMPA dealed with hydrochloric acid solution,NaON aqueous solution,hot water at 80℃,high and low temperature were also investigated. The results showed that the bonding strength of the RHMPA almost unchanged and exhibited an excellent chemical resistance to these conditions.
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    Effects of Zn(OH)2 on Corrosion Behavior of Galvanized Steel in Seawater
    LIU Shuan, SUN Hu-yuan, SUN Li-juan, FAN Hui-ji, LIU Zeng-wen
    2013, (8): 60-64.   DOI: 10.3969/j.issn.1001-4381.2013.08.010
    Abstract ( 909 ( PDF (2688KB)( 277 Citation
    Galvanized steel specimen was immersed in saturated Zn(OH)2 seawater solution to simulate the corrosive environment, using the mass loss method, scanning electron microscopy (SEM), polarization curves and electrochemical impedance spectroscopy(EIS) to study the corrosion behavior of galvanized steel. The results showed that the membrane of the Zn coating was damaged because of the corrosion products Zn(OH)2 adsorption. With the increased of immersion time, the charge transfer resistance decreased and the corrosion current density increased during the corrosion reaction of galvanized steel. Pitting on the galvanized steel surface was induced by the adsorption of corrosion products Zn(OH)2.
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    Effect of Passive Film Quality on Corrosion Resistance of Austenitic Stainless Steel and Chromaticity Inspection
    CHENG Cong-qian, FU Qin-qin, CAO Tie-shan, ZHAO Jie
    2013, (8): 65-69.   DOI: 10.3969/j.issn.1001-4381.2013.08.011
    Abstract ( 858 ( PDF (3910KB)( 277 Citation
    Effect of passive film quality on corrosion resistance of 304 austenitic stainless steel after air exposure and chemical passivation was investigated by using electrochemical impedance spectra. A novel inspection of the film quality was proposed based on cathodic reduction and chromaticity inspection. The results show that the compactness of passive film and corrosion resistance for the sample after chemical passivation are superior to that after air exposure. The chromaticity measurement is dependent on the applied potential for the samples after air exposure. The chromaticity measured value increases with decreasing potentials when the applied potential is lower than the reduction potential of outer Fe-rich oxide in passive film. However, the chromaticity for the samples after chemical passivation is close to 0. Based on cyclic voltammetry, it reveals that the chemical passivation improves the corrosion resistance of 304 stainless steel by enhancing the compactness of inner Cr-rich oxide in passive film. Experimental results suggest that the chromaticity inspection could be utilized to numerically characterize the quality of passive film.
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    Microstructure Simulation and Verification for GH4169 Alloy by Double Cone-shape Samples Deformation
    WEI Jia-hu, DONG Jian-xin, YU Jian, FU Shu-hong, YAO Zhi-hao, ZHANG Mai-cang
    2013, (8): 70-74.   DOI: 10.3969/j.issn.1001-4381.2013.08.012
    Abstract ( 686 ( PDF (1972KB)( 198 Citation
    The prediction models of microstructure evolution and calculation procedure for GH4169 alloy were established with a comprehensive consideration on the interaction of deformation parameters, increasing temperature and the cooling rate during hot deformation. Besides, a double cone sample was chosen as experimental shape, whose size was about Ø200mm×160mm for better reflect real situation that the distribution of strain, temperature, cooling rate were different in different sample locations. Then, the simulation and verification for microstructure evolution were carried out at the deformation temperature of 980, 1020, 1060℃ and 1120℃. The results showed that the double cone samples were in accordance with practice deformation situation. The prediction model of microstructure evolution was reasonable for using and it can achieve the real microstructure results for deformation.
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    Effect of Different Welding Material Matching and Aging Treatment on Microstructure and Mechanical Properties of Dissimilar Steel Welded Joints
    HUANG Ben-sheng, LIU Ge, HUANG Long-peng, LIU Hui, ZHANG Huai-hui
    2013, (8): 75-84.   DOI: 10.3969/j.issn.1001-4381.2013.08.013
    Abstract ( 646 ( PDF (6539KB)( 203 Citation
    The microstructure and mechanical properties of Q235/316L dissimilar steel welding joints were researched by using metallurgical microscope, universal testing machine, impact test enginery, microhardness tester etc. The results showed that microstructure and mechanical properties of dissimilar steel welded joints were improved in the process of Q235/316L dissimilar steel welding, while the A042 was used as a surfacing welding material and the A022 was used as a fill welding material.The performance dissimilar steel welded joints of 300℃×2h insulation and air-cooled aging treatment was superior to that of 500℃×2h,700℃×2h insulation, air-cooled aging treatment and non-aging treatment. It was caused by existence ferrite and pearlite, so, yield strength and tensile strength were greatly improved. At the same time, weld zone and 316L HAZ impact toughness were increased,due to the elimination of hydrogen and reverse change austenite amount of growth.
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    Research Status on Ceramic Cores and Shells for Superalloy Hollow Blades Investment Casting
    KANG Hai-feng, LI Fei, ZHAO Yan-jie, XU Hua-ping, WANG Fei, LÜ He-ping, SUN Bao-de
    2013, (8): 85-91.   DOI: 10.3969/j.issn.1001-4381.2013.08.014
    Abstract ( 998 ( PDF (1010KB)( 329 Citation
    The application background and key role as well as the basic performance requirements of ceramic cores and shells used for the investment casting of superalloy hollow blade were introduced,and the future development direction of ceramic cores and shells was described. The raw materials of the ceramic cores and shells, together with the manufacture methods and their influence on the properties were reviewed respectively. The research status and existing problems of leaching technics of ceramic cores were introduced. In addition, the important influence of positioning accuracy and the consistency of ceramic cores and shells on the quality of superalloy hollow blade was evaluated.
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    Progress in Research and Development of Electron Beam Technology in Metallurgy Refining Field
    TAN Yi, SHI Shuang
    2013, (8): 92-100.   DOI: 10.3969/j.issn.1001-4381.2013.08.015
    Abstract ( 670 ( PDF (1681KB)( 294 Citation
    Electron beam technology is an effective means for purifying solar-grade silicon, refining refractory metals and its alloy, preparing high purity special steel and super clean steel, because it has the advantages of high energy density and vacuum degree and it can be controlled accurately. In this paper, based on the basic principle of electron beam technology, the current situation of research and application of electron beam technology on the refining of several high-purity materials and alloys were reviewed. The present problems and the main research direction of electron beam technology were also proposed.
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