bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Additive on Structure and Corrosion Resistance of Manganese Phosphate Film on AZ91 Magnesium Alloy
Authors: Zhou Wan Qiu , Tang Wei , Zhao Qiang , Wu Shi Wei , Han En-Hou
Published: June 2011

Manganese phosphate conversion coating was prepared by adding addition agent towards phosphate bath. The structure was investigated using SEM/EDX, and the anti-corrosion performance was evaluated by electrochemical technique. It was found that the film presented in crystal structure, and the crystalloid grain transformed from large grain toward small particles upon the addition. The corrosion resistance was studied by polarization curves and EIS in 3.5%NaCl. Polarization curves showed that the corrosion potential of the coating shifted remarkably towards positive direction comparing with that of AZ91 substrate. EIS results indicated that the radius of the capacity impedance for phosphate film increased distinctly, which validated the excellent anti-corrosion performance of the film.
Influence of Silane on Corrosion Performance of Silane-Modified Acrylate Interpenetrating Polymer Network Coating on Magnesium Alloy AZ31
Authors: Zeng Rong Chang , Liu Chen Lan , Kong Ling Hong , Cui Hongzhi
Published: June 2011

The possibility that various silane treatments may enhance the corrosion resistance of a magnesium alloy AZ31 with silane-modified acrylate interpenetrating polymer network (IPN) coating has been investigated. Potentiodynamic electrochemical tests and neutral salt spray test were applied to evaluate the corrosion performance of the alloy. The results show that silane film improves corrosion resistance of the AZ31 alloy with and without IPN coating. The silane-modified IPN coatings improved more than 4 orders of magnitude of the corrosion resistance of the substrate.
Mechanical Properties and Microstructure Evolution of AZ31 Magnesium Alloy Sheet Subjected to High Strain Rates Loading of Different Orientations
Authors: Yang Yong Biao , Zhang Zhi Min , Wang Fu Chi , Han Jian Wei
Published: June 2011

Mechanical property tests of AZ31magnesium alloy sheet were carried out with compressive axis 0°，45° and 90° from normal direction respectively using Split Hopkinson Pressure Bar (SHPB). The results showed that the strain hardening rate for both 0° and 90° specimen decreases with increasing strain, and remain a constant approximately for 45° specimen at a strain rate of 2.8×103s-1. The flow stress of 45° specimen is the lowest compare with the other two specimens. Twined area fractions (TAF), dislocation multiplication and twinning system were characterized using optical microscopy (OM) and transmission electron microscopy (TEM). The results revealed that TAF for both 0° and 45° specimens are far less than 90° specimen at the same strain. Microstructure observation for specimens at a strain of 0.003 shows that dislocation multiplications for 0º specimen are far less than 45° specimen, and that {10-12}<10-11>twinning，{10-11}-{10-12}double twinning and twin intersection of vast amounts are activated for 90° specimen. Dynamic mechanical property anisotropy can be explained based on different microstructure evolution and plastic deformation mechanisms.
Microstructure and Mechanical Properties of MgMnAlZnCu High Entropy Alloy Cooling in Three Conditions
Authors: Li Rui , Gao Jia Cheng , Fan Ke
Published: June 2011

In this paper, alloy with composition of MgMnAlZnCu was designed by using the strategy of equiatomic ratio and high entropy of mixing. The microstructure and mechanical parameters of the new high entropy alloy cooling in three conditions were studied. The alloy was prepared by induction melting and then it was cast in copper molds in air, water and salt water respectively. The microstructure and properties of alloy samples were examined by microhardness tester, XRD, TEM, SEM and testing machine for material strength. The results showed that the alloy was composed mainly of h.c.p and Al-Mn quasicrystal phases. The alloy exhibit high hardness (431HV-467HV) and high compression strength (428MPa-450MPa) at room temperature. The alloy was fragile and the strains were from 3.29% to 5.53%.
Microstructure and Solidification Behavior of Permanent-Mould-Cast Mg-9Li-3Al-XSr Magnesium Alloy
Authors: Peng Xiao Dong , Yang Yan , Wei Qun Yi , Xie Wei Dong , Ning Xu
Published: June 2011

Mg-9Li-3Al-xSr (x=0wt%, 1.0wt%, 2.0wt%, 2.5wt%) magnesium alloys with different ingot sizees were prepared in furnace under the protection of argon atmosphere. The as-cast microstructure and solidification characteristics of Mg-9Li-3Al-xSr alloys were experimentally examined using optical microscopy, scanning electron microscopy and X-ray diffraction. The results indicate that Mg-9Li-3Al-xSr alloys are composed of α-Mg, β-Li, Mg17Al12, AlLi and Al4Sr phase. The grains of Φ10mm ingots are much smaller and the compound phase distributes much more uniformly than Φ90mm ingots. Solidification process of Mg-9Li-3Al-xSr alloys follows the principle of eutectic solidification. The microstructure of the series as-cast alloys is typical rodlike eutectic microstructure.
Microstructures and Mechanical Properties of AJ62 Magnesium Alloy with Y and Nd Elements
Authors: Ning Xu , Xie Wei Dong , Dang Chun Mei , Peng Xiao Dong , Yang Yan , Chen Yan Li
Published: June 2011

A series of Mg-6Al-2Sr-1.5Y-xNd (x=0, 0.3, 0.6, 0.9, 1.2) alloy samples were prepared and their microstructures were observed and mechanical properties were measured. The existing forms of Y and Nd were studied. The effects of Y and Nd on microstructure and mechanical properties of AJ62 alloy were investigated. The results show that the main existing forms of Y and Nd in AJ62 alloy are Al2Y and Al2Nd. The combined addition of rare earth Y and Nd can refine α-Mg matrix obviously and reduce the amount of the β-Mg17Al12 phases; after solid solution treatment, the tensile strength of the alloys rise first and fall later with increasing content of Nd. When the content of Nd is about 0.6%wt, the values of tensile strengthes are up to the maximum both at room temperature and at 448 K.
Microstructures and Mechanical Properties of As-Cast and Extruded Mg-2wt.%Zn Alloy Containing Dilute Content of Misch Metal
Authors: Le Qi Chi , Zhang Zhi Qiang , Cui Jian Zhong , Jia Zheng
Published: June 2011

Microstructures and Mechanical Properties of as-cast and extruded Mg–2wt.%Zn alloys containing dilute misch metal were investigated. RE additions were added in the form of relatively inexpensive cerium-rich misch metal (MM). The results indicate that the dilute MM addition has evidently effect the microstructure and mechanical properties of Mg-2wt.% Zn alloy. The grain refinement was improved and the amount of second phase precipitation was increased as increasing MM content in Mg-2wt.%Zn alloy from 0.2% to 1.5%, and the hardness determination and tensile test results show that the hardness of its ingot and the tensile strength of its extrusion rod were also enhanced, however, excessive MM addition would promote second phases forming network precipitating in grain boundary, which would result in the marked reduction of the plasticity of the alloy. Therefore, it is recommended that the MM content not exceed 0.6% in order to obtain high strength companying with relative higher elongation. The tensile properties of as-extruded Mg-2Zn-0.6wt.%MM alloy rod were UTS=266.7MPa, YS=213MPa, EL=14.5% which is similar to the corresponding properties of AZ31.
Microstructures and Mechanical Properties of Heat-Resistant High-Pressure Die-Cast Mg-4Al-6RE-0.3Mn (RE= La, Ce, Pr, Nd, Wt.%) Alloys
Authors: Leng Zhe , Zhang Jing Huai , Zhang Mi Lin , Meng Jian , Wu Rui Zhi
Published: June 2011

Mg-4Al-6RE-0.3Mn (RE=La, Ce, Pr, Nd, wt.%) magnesium alloys were prepared successfully by the high-pressure die-casting technique. The microstructures and tensile properties in the temperature range from room temperature to 200 °C were investigated. It was confirmed that the Mg-Al-RE-based alloys exhibited an outstanding die-cast character. The cross-section of test bar could be divided into the fine skin region and the relatively coarse interior region by a narrow band with fine structure. Two binary Al-RE (RE=La, Ce, Pr, Nd) phases with the former being the dominant one, Al11RE3 and Al2RE, occupied large grain boundary area. All the four alloys exhibited excellent tensile properties until 200 °C, which were mainly attributed to the fine grain size and the strengthening phase Al11RE3 with high volume fraction, fine acicular/lamellar morphology, "orderly stack” distribution and good thermal stability. The results of this work provided a basis for further investigation of the new heat-resistant high-pressure die-cast magnesium alloys designed to serve at temperature up to 200 °C.
Observation of Microstructural Refinement in Mg-3Sn-2Ca Magnesium Alloy Containing Minor Sr
Authors: Yang Ming Bo , Qin Cai Yuan , Liang Xiao Feng , Pan Fu Sheng
Published: June 2011

The microstructures of the Mg-3Sn-2Ca magnesium alloys with and without adding minor Sr were investigated and compared. The results indicate that adding 0.1 wt.% Sr to the Mg-3Sn-2Ca alloy can effectively refine the primary CaMgSn phases and grains. In addition, in the alloy containing minor Sr the volume fraction of the primary and eutectic CaMgSn phases appears to be decreased, whereas the volume fraction of the Mg2Ca precipitates seems to be increased. The mechanism for the microstructural change in the alloy containing minor Sr is possibly related to the effects of Sr additions on the onset crystallizing temperature and undercooling degree.
Photocatalystic Cathodic Protection of TiO2 Coating on AZ31 Magnesium Alloy
Authors: Wang Zhen Lin
Published: June 2011

Nano TiO2 and S, N co-doped TiO2 composite coatings with WO3 transitional layer were deposited on AZ31 magnesium alloy by sol-gel method. The morphologies, structure, mechanical properties, compositional depth profiles and anti-corrosion performance of the as prepared coatings were characterized by scanning electron microscope, X-ray diffraction, nanoscratch test, glowing discharge optical emission spectrometry and electrochemical method, respectively. The results show that the nano TiO2 coatings are continuous, uniform and dense with thickness ca.3-5μm, elements in the interface diffuse mutually during heat treatment; S-N co-doped TiO2 enhances the interface adhesion, WO3 transitional layer increases the total coating thickness and strengthens the adhesion to substrate with respect to unitary TiO2 coating; S, N co-doped TiO2 acts as visible light photocatalyst that can provide permanent cathodic protection for AZ31 magnesium using WO3 as electron restoring material.
Research on Heat Transfer during LFEC Processing by In Situ Temperature Measurement
Authors: Le Qi Chi , Zhang Zhi Qiang , Ru Li Li , Cui Jian Zhong
Published: June 2011

Low-frequency electromagnetic casting (LFEC) processing could improve not only the metallurgical quality of magnesium billet including refining grain size, reducing regional microstructural difference and lightening segregation, but also its surface quality due to the effect of applied electromagnetic field according to the results by microstructure observation and the numerical simulation. In this research in-situ temperature measurement was carried out in LFEC processing in order to investigate heat transfer behavior of billet during solidification. The effects of the electromagnetic conditions (frequency and the intensity) together with the casting temperature on the sump and the mushy zone were investigated in detail. The results indicate that all the casting conditions affect the temperature field of magnesium billet markedly during solidification. Electromagnetic field could decrease not only the sump depth but also the difference of regional temperature field along the solidification direction leading to much more uniform cooling rate.
Researches on a Composite Extrusion Approach Based on FEM Method and Experiments
Authors: Zhang Ding Fei , Zhang Jun Ping , Hu Hong Jun
Published: June 2011

This paper deals with a finite element model (FEM) for the extrusion of AZ31 alloy and extrusion experiments at different temperatures. The simulation is utilized to predict the extrusion force and strain at different temperatures. ES (extrusion-shear) process and direct extrusion are investigated at 370, 400 and 420°C to discuss the effects of different temperatures on the microstructures and mechanical properties with the extrusion ratio of 11.56. The simulation results obtained show that the extrusion force of ES process is much larger than direct extrusion because of the two corners. ES process could effectively refine the grains, especially the microstructure of the central region compared with direct extrusion. The bar extruded at 370°C shows the best microstructures and mechanical properties.
Structure and Magnetic Properties of MgFe2O4 Nanoparticles Prepared by the Low-Temperature Solid-State Reaction Method
Authors: Sun Jian Rong , Wang Zhi Guang , Wang Yu Yu , Wei Kong Fang , Li Fa Shen
Published: June 2011

MgFe2O4 nanoparticles with different grain sizes were prepared by the low-temperature solid-state reaction method. The X-ray diffractometer (XRD), vibrating sample magnetometer (VSM), superconducting quantum interference devices (SQUID) and 57Fe Mössbauer spectroscopy (MS) were used to characterize the structure, magnetic properties and surface anisotropy of nanoparticles. Oxygen parameters suggested that lattice distortion was decreased with reducing particle size. In comparison with the bulk material, smaller saturation magnetization (Ms) and larger coercive force (Hc) for nanoparticles were observed. The critical sizes for transition from multidomain to single domain and for superparamagnetic transition were estimated to be 25 nm and 28 nm, respectively. In summary, the fabricating conditions for the low-temperature solid-state reaction method are studied to improve Ms and reduce Hc of the films, making the films suitable to the applications of the magnetic targeted drug.
Study of Aluminum Coating Thermally Sprayed on AZ80 Magnesium Alloy Surface
Authors: Xu Hongyan , Chang Sen , Zhang Xing , Zhang Zhi Min
Published: June 2011

Aluminum (Al) coating was thermally sprayed on the surface of AZ80 magnesium (Mg) alloy. The Al-coating was deformed at 400°C with different deformation degrees of 15%, 30%, 45%, 60% and 80%. The corrosion properties of the AZ80 Mg alloys coated with Al-coatings were studied by potentiodynamic and galvanic tests in 3.5% NaCl solution; the adhesion strengths between Al-coatings and AZ80 substrate were also measured simultaneously by tensile test. The results showed that, Al-coating could decrease the corrosion rate of AZ80 Mg alloys, and the corrosion rate was related not only with the density of Al-coating but also with the adhesion strength of Al-coating. Before the formation of dense Al-coating, the corrosion rate of Al-coated AZ80 Mg alloys decreased with the increasing of bonding strength of Al-coating; after the formation of dense Al-coating, the corrosion rate of Al-coated AZ80 Mg was mainly determined by the structure of Al-coating. It was also revealed that with the increasing of deformation degree, the corrosion rate of the Al-coated AZ80 Mg alloys first decreased then increased, while the adhesion strength increased gradually. The corrosion rate of AZ80 Mg alloy coated with 60% deformed Al-coating was the lowest, which was only 19% of that of the AZ80 substrate.
Study of the Microstructure of AZ31B Magnesium Alloy under High Strain Rate Deformation
Authors: Mao Ping Li , Liu Zheng , Wang Chang Yi , Wang Zhi
Published: June 2011

In order to investigate the microstructure evolution under high strain rate deformation of magnesium alloy, AZ31B magnesium alloy was impacted by Split Hopkinson Pressure Bar within the strain rates of 496s-1 to 2120s-1, then the specimens were observed by optical microscopy. The results show that when the strain rate are relatively low (496s-1-964s-1), the microstructure is predominated by high density of twinning, while increase the strain rate to 2120s-1 the volume fraction of twins is decreased. This implies that at relatively lower strain rate the deformation mechanism of AZ31B magnesium alloy under impact loading is twinning; increasing the strain rate the prismatic slip and pyramidal slip may be active besides twinning.
Study on the Corrosion Resistance of Magnesium Alloy AZ81 with Rare Earth
Authors: Wu Yu Cai , He Rui , Li Lei
Published: June 2011

The influences of the different content of Rare earth La on the corrosion resistance of AZ81 in the simulated human fluid were studied. In order to further improve the corrosion resistance, different heat treatment procedures were studied. Results showed that with the increase of content of rare earth La, the grain size was refined and the corrosion resistance increased. The corrosion resistance was improved after T6 heat treatment (solid solution+ aging). Microstructure analysis showed that β-phases were precipitated in the T6 heat treatment process. Those fine β phases acted as corrosion barrier and impeded the corrosion extending.
Superplastic Forming Limit and Instability of AZ31B Sheet
Authors: Song Mei Juan , Wang Ling Yun , Liu Rao Chuan
Published: June 2011

The superplastic bulging test of AZ31B magnesium alloy sheet of 0.6mm thick was carried out on Alliance RT/50 tensile machine at 573K and 3.3×10-4S-1. It is found that either in tensile-compressive deformation or in bi-axis tensile deformation, the judgment criterion for local necking of superplastic deformation is dε2=0. The superplastic forming limit diagram(FLD) at 573K and 3.3×10-4S-1 was established for the first time.
The Effects of Al-Ca Compounds on Grain Refinement of Mg-Ca Alloys
Authors: Xiong Shu Tao , Pan Fu Sheng , Jiang Bin , Li Xiao Ke
Published: June 2011

In the present work, Al-Ca metallic compound was prepared in Mg-Ca alloys and the effects of Al-Ca metallic compound and different Al/Ca values on the grain refinement of Mg-Ca alloys were investigated by scanning electron microscopy and X-ray diffraction, and the mechanism of grain refinement of Mg-Ca alloys was discussed. The results showed that the grain size of Mg-0.5Ca alloy was obviously reduced from 550μm to 230μm due to the addition of Al. Al2Ca phase existed in these alloys and its morphology evolved from granular to rod-like. It is regarded as the main factor for the grain refinement.
The Evaporation Effect of Front Keyhole Wall in Penetration Welding with an Electron Beam
Authors: Luo Yi , Liu Jin He , Du Chang Hua , Xu Hui Bin , Li Chun Tian
Published: June 2011

The process of vacuum electron beam welding is characterized by deep-penetration with the action of keyhole effect. The assumption of simple cylindrical physical model of keyhole is reasonable according to the thermal transfer of the keyhole effect during welding. There is an intensive evaporation arises from the front keyhole wall owing to the high energy density of electron beam. Therefore, an analysis model of heat transfer at the interface of vapor phase and front keyhole wall was proposed to the temperature calculation on the basis of heat transfer theory. The evaporation of the primary elements, which are Mg, Al, Zn and Mn in AZ series magnesium alloy, can be analyzed by the model, as well as the influence of keyhole radius varying on the temperature at vapor-solid interface offront keyhole wall. And dimensionless parameters are introduced to analyze the influence of the process condition on the thermal effect. The calculation results show that Mg and Zn are vulnerable to vaporize loss during the vacuum electron beam welding on AZ series magnesium alloy, and the evaporation of Mg occurs earlier than Zn. A longer electron beam acting duration and smaller keyhole size will increase the temperature of the front keyhole wall significantly, which has a considerable influence on the evaporation effect of the elements.
The Tendency of Oxide Inclusion on Magnesium Alloys Intake Manifold in Tilt Cast
Authors: Liu Tao , Tang Quan Bo , Zhao Jian Hua
Published: June 2011

The oxide inclusion formation tendency in tilting cast magnesium alloys intake manifold was studied by numerical simulation. Two different programs were used for results comparison. The results indicate that it was easier to form oxide inclusion when connecting foundry ladle with the junction panel of intake manifold instead of cavity resonator. The oxidation mixture is prone to appear at the ribs and outer wall of the four main air piles of the intake manifold. The formation of oxide inclusion would be influenced by the flowing state of the melt during casting process.
Thermal Analysis during Solidification of Mg-4%.wtAl Alloy during Lost Foam Casting Process
Authors: Hou D.H. , Liang S.M. , Chen Rongshi , Han En-Hou , Dong C.
Published: June 2011

The lost foam casting (LFC) process utilizes the expanded polystyrene (EPS) foam pattern for the production of metallic components. The thermal degradation of the foam pattern has a significant effect on microstructure of the component. Dendrite coherency is important for the determination of the formation of the solidification structure and cast ability of alloys. The effects of the dendrite coherency on grain size in Mg-4Al alloy have been studied using the two-thermocouple thermal analysis technique in the solidified sample. The results also indicate that the grain size increases with the temperature interval between liquids (TN) and dendrite coherency point (TDCP), The solid fraction at DCP (fsDCP) expressed in percent strongly dependents on the dendrite morphology during solidification.
Phase Equilibria in Co-Rich Co-Al-W Alloys at 1300°C and 900°C
Authors: Xue Fei , Wang Mei Ling , Feng Qiang
Published: June 2011

The phase equilibria of Co-base trial alloys of Co-9Al-7.5W, Co-5.5Al-10W and Co-9Al-3W at 1300°C and 900°C were determined in the present investigation. The experimental alloys were γ single-phase alloys at 1300°C, although the existence of the γ' phase and the ε phase was identified due to cooling effect. The nearly cuboidal γ' phase and the plate-like DO19 phase in alloys 9Al-7.5W and 5.5Al-10W were coarsened after long-term annealing at 900°C. It is suggested that the alloy 9Al-7.5W was in γ+γ' two-phase region, while the alloys 5.5Al-10W and 9Al-3W were in γ+DO19 two-phase region and γ singe-phase region at 900°C, respectively.
Effects of Load and Sliding Distance on the Wear Properties of Hybrid Friction Materials
Authors: Zhang Ning , Chen Li Xiang , Yin Yan Sheng , Han Ye , Wang Zong Feng
Published: June 2011

Hybrid friction materials were manufactured with glass fiber, potassium titanate whisker and aramid fiber as reinforcement and the phenolic resin modified by lumbar pericarps oil as matrix material. The effects of load and sliding distance on friction and wear properties were studied by single variable experiments. The worn surfaces of the samples were studied by Scanning Electron Microscope (SEM). The results showed that friction coefficient and wear rate can be significantly increased when the load was increased up to 250N. The friction coefficient varied between 0.25 and 0.3 while the wear rate reduced to 0.49×10-6 g/(N·m) in the sliding distance longer then 80m. Wear mechanism of samples were to be adhesive and abrasive wear.
Microstructural Model of Enveloping-Core Fiber Distribution of Conifer Wood and Research on Biomimetic Wood Composite
Authors: Chen Bin , Yin Da Gang , Yuan Quan , Luo Ji , Fan Jing Hong
Published: June 2011

The observation on conifer wood shows that wood is a kind of biocomposite consisting of wood fibers and lignin matrix. The wood fibers are embedded in the lignin matrix with parallel distribution. It is also observed that the wood fibers continuously envelop the columned branch cores in the wood forming a kind of enveloping-core fiber distribution (ECFD). The ultimate load of the composite model with the ECFD is investigated and compared with that of the composite model with non-enveloping-core fiber distribution (NECFD). It shows that the strength of the composite model with the ECFD is larger than that of the composite model with NECFD. A kind of mimetic-wood composite specimens with the ECFD is also fabricated. The test was carried out with ECFD specimens and compared with that of the composite specimens with the NECFD. The result show that the ultimate strength of the former is significantly larger than that of the latter.
Experimental Study on Mechanical Properties of X-Cor Sandwich
Authors: Bi Jian Ping , Dang Xu Dan , Wang Xin Li , Xiao Jun , Chen Hai Jun , Zhang Hong Song
Published: June 2011

In this study, by changing Z-pin’s insertion parameters, the X-cor sandwich was prepared with vacuum curing molding process. The effects of Z-pin’s insertion angle, insertion density and diameter on compression, shear and tension properties were studied. The results show that Z-pin’s insertion parameters can significantly affect the mechanical properties of X-cor sandwich. The compression properties of X-cor sandwich are reduced, while shear properties are improved by the increase of Z-pin’s insertion angle. As Z-pin’s insertion angle increases the tension modulus increases while the tension strength firstly increases and secondly decreases. The mechanical properties increase with the increase of Z-pin’s insertion density and diameter. Compared with the foam core sandwich, the mechanical properties of X-cor sandwich are significantly improved in both modulus and strength.
Preparation of Ultrafine White Cement and its Hydration
Authors: Du Gao Xiang , Guo Wei Juan , Liao Li Bing , Xue Qiang , Wang Nan , Ban Jian Wei
Published: June 2011

The ultrafine grinding of white cement and its hydration were studied. The ultrafine grinding parameters, such as crushing pressure and feeding pressure of jet mill in a lab scale were optimized. The influence of the particle size distribution of ultrafine white cement and the usage of water reducer on the standard thickness and early age strength of white cement paste was investigated. The results indicated that the ultrafine white cement with d50=4.62 µm and d90=10.48 µm can be obtained when the crushing pressure was 0.7 MPa and the feeding pressure was 0.4 MPa. The standard thickness of white cement paste decreased from 30.5 % of the raw material to 26.0% of the ultrafine white cement (d50=4.42 µm, d90=10.26 µm). The use of 2% naphthalene-based water reducer can reduce 15.4% water consumption. The 3d compressive strength of pure ultrafine white cement sample reached 174% of that of raw white cement. The 28d compressive strength of ultrafine white cement with 3% naphthalene-based water reducer added was 22.9% of that of pure ultrafine white cement. A large number of needle-shape nanometer ettringite (AFT) was generated in the early stage of hydratration and layered C-H-S was formed with the decreasing of the amount of AFT in the later stage of hydratration. It’s supposed that the formation of the large number of needle-shape nanometer AFT was related to the reducing of the particle size of C3A during the ultrafine grinding and the no adjustment of the amount of the added gypsum, which resulted in the faster hydration of C3A.
Study on Foaming Behavior of Microcellular PP/Inorganic Powder Composites
Authors: Gong Wei , Zhang Chun , Yu Jie , Zhu Jian Hua , He Li
Published: June 2011

The modified inorganic powder material (one-dimensional MgSO4 whisker, two-dimensional Mica, zero-dimensional SiO2 ) was added into polypropylene with 5% wt. The microcellular foam PP composite was prepared under the condition of twice-open mold. According to the principle of interfacial adhesion，Liquid-solid interface free energy of PP composite system was calculated by means of the contact angle. Based on heterogeneous nucleation theory, foaming behavior of microcellular foam material was characterized quantitatively by interfacial behavior. The effects of different inorganic powder material on foaming behavior were analyzed in microcellular foam polypropylene. The results indicated that the minimum nucleation energy barrier of PP/Mica composite system is 46.94N.mwith the nucleation rate in 5.53×1011. After foaming, the cell diameter of the composite is 22.1μm and the cell density is 6.92×108 months/cm3.
Effect of the LaNd Addition on Melting Point and Spreading Properties of Bi5Sb8Sn Solder Alloy
Authors: Sheng Yang Yang , Yan Yan Fu , Han Cun Cang , Tang Kun , Zhao Kuai Le , Xu Zhi Wei
Published: June 2011

Bi5Sb8Sn solder alloy is the most promising alternative to existing high-Pb solder as high-temperature lead-free soft solder alloy series whose melting point is about 264°C and have better conductivity and mechanical properties, but its wettability need to be improved. In this paper a novel Bi5Sb8SnLaNd quaternary alloy have been developed by adding a small amount of mixed rare earth LaNd elements into Bi5Sb8Sn solder alloy to improve the technological properties of Bi5Sb8Sn alloys. The experimental results showed that adding 0.1～0.3wt.% LaNd into Bi5Sb8Sn solder alloy made the melting point changed slightly, but resulted in the wettability of the solder alloy significant improvement. Compared with the matrix of Bi5Sb8Sn, the spreading area of solder alloy was about 20% bigger when the content of LaNd is 0.1wt.%. With increasing the content of rare earth LaNd, the spreading area of solder alloy decreased, but it was still higher than that of the matrix of Bi5Sb8Sn. This may be mainly attributed to the formation of new phases with rare earth and the thickness of the substrate intermetallic compounds in the Bi5Sb8Sn solder alloy.
Numerical Simulation Analysis of Temperature Field on Silicon Carbide Synthesis Furnace
Authors: Li Yong Gang , Hu Yang Dong , Wu Lian Ying , Li Hong
Published: June 2011

Based on heat percolation theory and thermal coefficient equation of various layer-compositors, the effective thermal conductivity of silicone carbide（SiC）synthetic material was obtained, and the effective heat capacity under the complicated thermal effect in the process of raising temperature figured out in the present investigation. Based on the experimental results and using the finite element numerical model of nonlinear dynamic heat transfer process, the temperature field in SiC synthesis furnace was simulated by open source finite element software-FECsoft. And the dynamic laws of temperature distribution and thermal gradient of the furnace, the relation between the furnace core’s temperature and the energy consumption and output were obtained. Based on the above analysis, some measures to save energy and increasing output of the silicon carbide synthesis furnace were proposed in this paper.
Structure and Precipitation of Strip As-Cast and Hot-Rolled by TSCR on Oriented Silicon Steel
Authors: Yu Yong Mei , Xu Yun Bo , Zhang Yuan Xiang , Zhang Ting , Zhang Xiao Ming , Wang Guo Dong
Published: June 2011

The simulation studies were carried out on the oriented silicon steel produced by thin slab casting and rolling (TSCR) and twin-roll strip casting in the laboratory. The precipitation of inhibiter, formation of microstructure and texture were investigated before cold rolling. The inhomogeneous microstructure and texture gradient were observed in the 7-pass hot-rolled strip（2mm）for TSCR process, and texture gradient was not changed after normalizing, and the twin-roll strip casting directly supplied a strip with approx 2mm of thickness being same as that of hot-rolled strip by TSCR. The microstructure of twin-rolling casting strip was almost composed of all equiaxed grains which similar to the normalizing microstructure in TSCR process, but the random texture was obtained by twin-rolling strip casting. The dispersed and clustered precipitates were presented in hot-rolled strip when the ingots were soaked at 1200°C and 1150°C respectively for the TSCR process. And disperse and acicular precipitates were observed by TEM for air-cooling cast strips for process twin-rolling casting.
A Novel Wear Resistant Glass-Ceramic Coating Material
Authors: Han Ye , Yao Shu Yu , Zhang Wei Wei , Gu Ming , Yao Yu Sui
Published: June 2011

A novel wear resistant glass-ceramic coating system (based on SiO2-B2O3-Al2O3 glass system) on iron based substrate was developed. Friction coefficient, wear rate and coefficient of thermal expansion of coating material were evaluated using suitable methods. The coating materials and the resultant coatings were characterized using differential thermal analysis (DTA), X-ray diffraction analysis (XRD) and Scanning Electron Microscope (SEM). XRD analysis of the coating materials showed presence of a number of microcrystal. SEM micrographs indicate strong chemical bonding at the iron-ceramic interface. The coating material showed perfect properties for protection the iron substrate from abrasion.
Corrosion Behavior of High-Strength Pipeline Steel and Coatings in the Simulated Sea Water Environment
Authors: Wang Bing Ying , Sun Zhen Tong
Published: June 2011

Four different metal coatings of pure aluminum, aluminum zinc alloy, titanium, aluminum Titanium were prepared on the surface of X80 pipeline steel by the method of arc spraying.The microstructures and combination method between the four coatings and substrates were observed by means of metallurgical microscope.This paper use 3.5%(mass fraction) NaCl solution to simulate seawater. The corrosion potential, average corrosion rate and corrosion current density of the four metal coatings were studied through the immersion test, salt spray test and electrochemical experiment in 3.5% NaCl solution.According to the results,analyse the corrosion mechanism of different coatings compared to the different corrosion resistances. The results showed that the Al-Zn coating has the excellent comprehensive corrosion resistance.
Fabrication of Ni-Based Composite Coating Reinforced with NbC Particles by Laser Cladding
Authors: Dong Gang , Yan Biao , Deng Qi Lin , Yu Ting , Wang Yu Xin , Yang Yin Hui
Published: June 2011

The in situ synthesized NbC particles reinforced Ni-based alloy composite coating has been successfully prepared on 1045 steel substrate by laser cladding a precursor mixture of Ni-based alloy, graphite and niobium powders. The microstructure, phase composition and wear property of the composite coating are investigated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and dry sliding wear test. The experiment results show that the coating is uniform, continuous and free of pores and cracks with excellent bonding between the coating and the substrate. The microstructure of the coating is mainly composed of γ-Ni dendrite, a large amount of interdendritic eutectics of M23(CB)6, N3B with γ-Ni, M23(CB)6 type carbides and dispersed NbC particles. The growth mechanism of the NbC particles with cores is nucleation-growth and the un-melted niobium may act as the nucleation core for NbC, Compared to the pure Ni-based alloy coating, the hardness of the composite coating is increased about 36 %, giving a high average hardness of approximate HV0.2750. Moreover, the wear volume and wear rate of the composite coating are decreased about 50 % and 42 %, respectively. This is attributed to the presence of in situ synthesized NbC particles and their well distribution in the coating.
High-Temperature Oxidation Resistance of Electroless Ni-P-ZrO2 Composite Coatings
Authors: Tan Ming Feng , Sun Wan Chang , Zhang Lei , Zhou Quan , Ding Jin
Published: June 2011

Electroless Ni-P coating containing ZrO2 particles was successfully co-deposited on low carbon steel substrate. The surface and cross-sectional micrographs of the composite coatings were observed with scanning electron microscopy (SEM). And the chemical composition of the coating was analyzed with energy dispersive spectroscopy (EDS). The oxidation resistance was evaluated by weight gains during high temperature oxidation test. The results showed that the embedded ZrO2 particles with irregular shape uniformly distributed in the entire Ni-P matrix, and the coating showed a good adhesion to the substrate. The weight gain curves of Ni-P-ZrO2 composite coatings and Ni-P coating at 923K oxidation experiments were in accordance with . The ZrO2 particles in Ni-P matrix could significantly enhance the high temperature oxidation resistance of the carbon steel substrate as compared to pure Ni-P coating.
Inhibition Behavior of a Novel Acidification Inhibitor for Steels at High Temperature
Authors: Xue Juan Qin , Wu Ming , Li Jing Xian , Tang Chang Bin , Yin Cheng Xian
Published: June 2011

The QL-03 corrosion inhibition system is obtained by the compounds of quinoline quaternary ammonium salt，mannich base and synergist. The mechanism of QL-03 with HP13Cr in 20%HCl is investigated by potentiodynamic polarization curves, EIS and weight loss measurements. The results show that the inhibition efficiency towards HP13Cr steel is improved greatly and reaches as high as 90% at 90°C, as a mixed corrosion inhibition system. Cumulating the inhibition efficiency from electrochemical results is more reasonable than weight loss result.
Investigation of Parameters’ Effect on Segmentation Cracks Formation in Zirconia Coating
Authors: Du Zhong , Wang Quan Sheng , Ma Zhuang , Li Yun Kai , Liu Yan Bo
Published: June 2011

The thermal barrier coatings with segmentation cracks have been proved with excellent thermal shock resistance property, but it is unclear that how the spray parameters affect the initiation of segmentation cracks. In order to find the relationship, orthogonal design experiments were used to analyze the effect of parameters, including spray distance, transfer speed, and powder feedrate. It is found that the descending order of parameters according their effect on the formation of segmentation cracks is: spray distance, feedrate, and the transfer speed. Furthermore, the parameters for getting high segmentation crack density are: spray distance is 55mm, feedrate is 2.5RPM and transfer speed is 100mm /s.
Nitrite, Nickel-Free Electrophoretic Coating Phosphating Solution
Authors: Wang Xiu Chun , Pan Xi Qing , Liu Shuo , Zhang Jing , Ma Jie
Published: June 2011

Cathodic electrophoretic coating is mainly used on automobile coating lines, before coating treatment the phosphating process is needed to enhance the adhesion and corrosion resistance of the coating layer. Currently toxic nitrite accelerator is widely adopted in the process of cathodic electrophoretic coating phosphating, as well as some polluting additives like nickel ions. Because of its great amount, phosphate solution become one of the major pollution sources on the automobile coating lines. In this study, the complex composed of non-toxic hydroxylamine, inorganic salts, etc. was chosen as phosphating accelerator, and without adding nickel ions, an environmental friendly cathodic electrophoresis phosphating solution was obtained. The phosphating film was compact, with good alkali resistance and good adhesion. Salt spray test showed that the cathodic electrodeposition coating had good corrosion resistance. As the hydroxylamine is stable in the phosphating solution, One-component phosphate concentrated solution can be produced.
Properties of Oxide Film on the Surface of ZrHX(x=0~2)
Authors: Chen Wei Dong , Yan Shu Fang , Zhong Xue Kui
Published: June 2011

Oxidation behaviors of ZrHx(x=0~2) in O2 at 600°C were investigated. The influences of temperature and oxidation time on mass gain of the oxide film were studied. The phase structure and morphology of the oxide film were analyzed by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The result indicates that the oxidation behavior of zirconium is greatly changed after absorbing hydrogen. The oxidation rate of zirconium hydride decreased with increasing of hydrogen content. The thickness of the oxide film decreases and the uniformity of oxide film declined with increasing of x value. Some holes and creaks present in the oxide films when x value is 1.8 and 2. The similar textured oxide film on the surface of ZrHx(x=0~2) is found and the main phase of the oxide films is monoclinic ZrO2 of the baddeleyite structure. A detectable amount of tetragonal ZrO2 appeal in all the samples. A protective textured oxide film can be formed on the surface of ZrHx(x=0~2), making it ingerate and thick is important to reduce hydrogen loss.
Properties of Sputtered NiCrAlY Used for Protective Gun Tube Coatings
Authors: Zhang Jian , Guo Cean , Zhang Gang , Wang Chong Rui , Hao Shi Ming
Published: June 2011

NiCrAlY coatings were deposited on CrNi3MoVA steel substrates by means of magnetron sputtering. The coatings were characterized in terms of their microstructure, hardness, friction coefficient, high-temperature oxidation resistance. Micro-indentation and tribometer testers were employed to measure the mechanical properties of NiCrAlY coatings and CrNi3MoVA steel. The results showed that the hardness of the coatings ranged from 5.7 to 5.9 GPa, with a higher value than that of CrNi3MoVA steel(4.1-4.3 GPa). The coefficient of steady-state friction of the coatings against 45-carbon-steel balls ranged from 0.35 to 0.40, with a lower value than that of CrNi3MoVA steel(0.63-0.68). The isothermal oxidation behavior at 850°C of the coatings were studied in comparison with CrNi3MoVA steel substrates. The results indicated that NiCrAlY coatings substantially increase the high-temperature oxidation resistance of CrNi3MoVA steel and the oxidation process was retarded mainly by the presence of outer complex oxide scales and a continuous Al2O3 inner layer on the coating.
Research on Properties of SiC Coating Inert Anode for Aluminum Electrolysis
Authors: Zhang Li Peng , Yu Xian Jin , Ge Zhi Wei , Dong Yun Hui , Li Dang Gang , Zhang Ya Li
Published: June 2011

The carbon composite materials with silicon carbide coating were prepared for aluminum electrolysis as inert anode. The oxidation resistance, corrosion resistance and electrical conductivity are researched respectively. The results showed that the inert anode had high anti-oxidation, corrosion resistance and high conductivity. The oxidation kinetics curve of the material obeys typical line-logarithmic law. The corrosion occurs mainly before 25 hours. The electric conductivity was stable and good, had the electric conductivity property of the semiconductor. The conductivity increased with temperature increasing, the conductivity at 850°C was 102S/cm
Improving the Bonding Strength of Y2O3 Coatings on Steel Substrates through a YOX Adhesion Layer
Authors: Lv Wei Ling , Liu Jun , Tang Tao , Yang Ling , Lei Rong , Qiao Li Jie , Cao Jiang Li
Published: June 2011

Y2O3/YOx composite coatings with different YOx adhesion layers were fabricated on 316L stainless steel substrates through reactive magnetron sputtering. The YOx adhesion layers were deposited by radio frequency reactive magnetron sputtering with different oxygen partial pressures at a total pressure of 1.2 Pa. The Y2O3 coatings were deposited by bipolar pulse reactive magnetron sputtering. The relationships between the microstructures, phase compositions, interfacial adhesion of the composite coatings and the oxygen partial pressure used for deposition of the YOx adhesion layers were investigated. The microstructures and phase compositions of the coatings were characterized by scanning electronic microscopy and X-ray diffraction. The bonding strength of the coatings was measured by scratch tester. The results showed that the bonding strength of the Y2O3/YOx composite coatings reached the maximum value when the oxygen partial pressure was 0.18 Pa.
Study of Y2O3/Er2O3 Multilayered Coatings Deposited by Magnetron Sputtering
Authors: Liu Jun , Lv Wei Ling , Tang Tao , Zhao Si Xiang , Lei Rong , Qiao Li Jie , Cao Jiang Li
Published: June 2011

The yttria-erbia multilayered coatings were prepared on 316L stainless steel substrates by bipolar pulse magnetron sputtering. Structures of these coatings were examined by X-ray diffraction and scanning electron microscopy. Bonding strength of these coatings on 316L stainless steel substrates was measured by scratch tester. Nano-hardness of these coatings was measured by nano-indenter. Comparative studies of the mechanical properties of the single-layered yttria coatings and multilayered coatings were conducted, and the seven layered coatings presented the highest bonding strength and nano-hardness as well as elastic modulus.
The Improvement in Oxidation Resistance of Magnesia-Carbon Refractory Bricks by Al4SiC4
Authors: Li Liang , Wang Shi Feng , Chen Shi Bing
Published: June 2011

Oxidation of carbon is the main problem in magnesia-carbon refractory bricks. Al4SiC4 powder is an excellent antioxidant which has obvious practical significance. It was prepared by vacuum sintering at 1700°C in vacuum sintering furnace. The effect of Al4SiC4 on the oxidation resistance of magnesia-carbon bricks were investigated at 1500°C. The thickness of decarburized layer of bricks was measured and the oxidized situation of the bricks was examined by XRD, SEM and EDAS. The decarburization layer became thin with adding Al4SiC4 powder. Magnesium alumina spinel (MgAl2O4) was determined to be present by characterization studies on Al4SiC4 added specimens and phase evolution of MgAl2O4 spinel formation were investigated by XRD. The optical microscope and EDAS indicated that the spinel diminished the open pores owing to its volume expansion and formed a protective layer on the surface. The results suggested that the spinel had an excellent effect on the oxidation resistance of bricks. In addition, compared with adding other aluminum-containing antioxidants, the specimens added Al4SiC4 had better stability from high temperature to room temperature.
Effect of Initial Microstructure on Deformation Mechanisms of AZ31 Magnesium Alloy
Authors: Mo J.P. , Cheng Xiao Nong , Ru J.M. , Xu Xiao Jing
Published: June 2011

Three kinds of magnesium alloy (AZ31) with different initial microstructure were subjected to tensile deformation. The microstructure before and after tensile deformation were examined. It was found that the deformation mechanisms of the three kinds of magnesium alloy were considerably different. Mg alloy with the coarse grains (about 50mm) along with little dislocation inside deformed by twining and dislocation mechanisms, accompanied with an enormous change of crystal orientation as well as a great increase of hardness. Mg alloy with the fine grains/twins (about 3mm) together with high density of dislocations inside deformed by dislocation mechanisms, accompanied with little change of crystal orientation and hardness. The magnesium alloy with the initial microstructure of fine grains (about 3mm) together with little dislocations inside deformed by dislocation and grain boundary sliding mechanisms, accompanied with little change of crystal orientation, but a large increase of hardness.
Thermal Corrosion Behavior of NiCoCrAlY Coatings Prepared by Different Thermal Spraying Methods
Authors: Sun Jie , Zhao Dan , Zhang Li Li , Tan Yong
Published: June 2011

The protection of thermal parts has become one of the most important techniques with the development of high capability and high thrust-weight ratio for advanced aeroengine. In this paper, using the nickel base superalloy as the substrate, the thermal corrosion performances of NiCoCrAlY coatings using different thermal spraying methods, which consisted of high velocity oxy-fuel (HVOF), detonation spraying (DS), atmospheric plasma praying (APS) and low pressure plasma spraying (LPPS), were studied. The thermal oxidation experiments, which consisted of isothermal oxidation and cycling oxidation experiments were performed to character the thermal performances. From the results, it was shown that the NiCoCrAlY coatings prepared by high velocity oxy-fuel method were slight for 100 hours at 1100°C. The surface of the NiCoCrAlY coatings prepared by HVOF had a dense, continued Al2O3 oxide layer. Among all the methods to prepare NiCoCrAlY coatings, the method of high velocity oxy-fuel showed excellent performance.