bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite Element Simulation of Laser Cladding Layer Crack by Micro-Regulation Forging
Authors: Zhou Ju , Qiu Chang Jun , Tang De Wen
Published: October 2010

Micro-plastic deformation is produced on the surface of the laser cladding layer by micro-forging, and crack makes a change in cladding layer. In this paper, a finite element model with a simplified panel strain model elastic-plastic of stress and strain relationship and adaptive meshing technique was used to simulate laser cladding layer crack by using DEFORM-2D software. Laser cladding process of cracks by micro-regulation forging is simulated. Comparing to the measurement of crack width, the results show that micro-forging can make the surface of laser cladding layer the residual tensile stress to adjust compressive stress, and the micro-forging can significantly reduce or eliminate the laser cladding layer crack. Reasonable and effective regulation of high-frequency micro-forging can improve the surface quality in micro-cladding layer.
Finite Element Analysis of Thermal Stress in Multi-Arc Ion Plated ZrTiN Hard Coatings
Authors: Yan Pei , Deng Jian Xin , Cui Hai Bing , Ai Xing , Zhao Jun
Published: October 2010

The thermal stresses generated in ZrTiN coating deposited on HSS and tungsten carbide substrates are investigated by finite element analysis and calculated by mathematics model. FEM analysis provides detailed information about all stress components. The influence of deposition temperature, substrate materials, coating thickness and interlayers on the generation is analyzed. The thermal stress of coatings has a linear relationship with deposition temperature, and an inverse relationship with the coating thickness. The results of simulated thermal stress are in accordance with the analytical method. The highest shear stress found at the interface between the coating and substrate indicates that the interface is the critical location which is learned from the failure point of view. Results also show that the insertion of TiZr interlayer between the coating and substrate can reduce the stress components especially the shear stress. The interlayer thickness has a great effect on stress reduction.
A Damage Cohesive Model for Simulating 90° Peel Propagation in Anisotropic Conducive Adhesive Bonding
Authors: Zhang Jun , Zhao Zhong Yao , Wei Xin Li
Published: October 2010

A modified cohesive zone interface model that has a damage factor couple with the thermal cycle and humidity aging was proposed. The damage factor not only can change the cohesive zone strength acting but also can effect on the energies of separation. The modified cohesive zone interfacial model is developed and implemented in ABAQUS, as a user element subroutine, to simulate the peeling process for the specimen bonding by anisotropic conducive adhesive film (ACF) under the thermal cycle and humidity tests. Finite element explicit code and the constitutive relation of this element has been defined by the user-defined mechanical material behaviour (VUMAT). The bulk material element selected is a 4-node bilinear plane stress quadrilateral element, and the reduced integration and hourglass control are also adopted. The numerical simulated results accorded well to the experiments to illustrate the validity of the new model.
Corrosion Resistance of Brush Plated Pb/Ni Multilayer Coatings in a Simulated Environment of PEMFC
Authors: Tan Jun , Qian Yao Chuan , Xing Ru Xin , Hu Zhong Xiang
Published: October 2010

Pb/Ni multilayer coatings, with either Pb or Ni as the top layer, were brush plated on ANSI 304 stainless steel to improve its performance as bipolar plates in polymer electrolyte membrane fuel cells (PEMFC). Surface morphology and cross-sectional microstructure of the coatings were characterized with scanning electron microscope (SEM) and optical microscope, respectively. The corrosion resistance of brush plated coatings in a simulated PEMFC environment was investigated using both three-electrode method and immersion of 300 h. Coating surfaces after the immersion were characterized with energy dispersive X-ray spectrometer (EDS). The results show that the multilayer coatings were smooth, dense, and small in grain size with clear layered structure. In the simulated PEMFC environment, the corrosion of multilayer coatings was mainly uniform corrosion. Coatings with different top layers exhibit different corrosion behaviors. Ni layer was corroded preferentially as the anode while the Pb layer was protected.
Effect of Ultrasonic Impact Strengthening Treating on Microstructure and Properties of AZ91D Magnesium Alloy
Authors: He Bo Lin , Yu Ying Xia , Miao Yan Ping
Published: October 2010

Magnesium alloy is one of the most useful structural materials in the future. But the research report about surface strengthening of magnesium alloy is little in home and abroad. Ultrasonic impact strengthening treatment was carried out on AZ91D magnesium alloy, the change characteristics of surface microstructure was studied using SEM. The scratch hardness and wear-resistance were tested for both ultrasonic impact treatment and un-treated specimen using HRA-150 type Rockwell hardness tester and M-2000 model wear tester. The experimental results indicate that after ultrasonic impact, the grain boundary on the surfaces of AZ91D is obviously refined. When the ultrasonic impact time are 20 min, 30 min and 50 min, the scratch hardness on the surface of AZ91D increases 7.2%, 16.96% and 28.90%, respectively. For ultrasonic impact time of 50 min, the wear-resistance of treated specimen could be increased to 39.63% and 37.56% respectively for the wear time for 2 and 5 min. With increasing the ultrasonic impact time, the wear scar on the surface is become narrow. It is an effective method to increase the scratch hardness and wear-resistance of AZ91D magnesium alloy by using ultrasonic impact strengthening treatment.
Analysis and Calculation of Electrodeposition Process of Zn Alloy Coatings
Authors: Fan Yun Ying , Chen Dong Hua , Liu Xiao Jing
Published: October 2010

Electrodeposited Zn-Fe alloy coating has good anti-corrosion performance and has been widely applied to protect steel materials from corrosion. In this paper, Zn-Fe alloy coatings were plated from acidic sulphate bath, and the relationship between real concentration of metallic complexes ([ZnL+] and [FeL+]) in the bath, which was calculated through solving nonlinear equations by METLAB software, and components of alloy coatings was studied. When ZnSO4•7H2O added in the bath increases from 10 g/L to 50 g/L, the ratio of ferrous complex to total complex decreases from 81.96% to 46.76%, simultaneously the iron content in Zn-Fe alloy coatings decreases from 26.82% to 6.32%. As FeSO4•7H2O and (NH4)2SO4 added in the bath increases from 40 g/L to 80 g/L respectively, the ratio of ferrous complex to total complex increases from 50.02% to 66.23% and from 58.65% to 60.37% respectively, simultaneously the iron content in coatings increases from 8.26% to 13.77% and from 9.28% to 11.92% respectively. The results show that variation of concentration of metallic complexes in the bath can lead to variation of components of coating proportionally.
Hybrid Finite Element Formulation for Temperature Prediction in Carbon Nanofiber Based Composites
Authors: Wang Hui , Zhao Xin Juan
Published: October 2010

The temperature distribution in nanoscale cylindrical representative volume element (RVE) with centered carbon nanofiber (CNF) was modeled by the developed hybrid finite element approach, which used the axisymmetric Green’s function to approximate the interior field within the element, while the independent element boundary field with conventional shape functions was assumed to keep the continuity of field variables between adjacent elements. As a result, coupling with the constructed hybrid functional to link the independent interior and boundary fields, the solving linear system of equations with boundary integrals only were obtained. Numerical examples were given to show the accuracy of the proposed approach, and results were found in good agreement with those of ABAQUS. Also, it was obvious that the surface temperature of nanofiller almost kept constant during heat transfer, due to the large difference of thermal properties between nanofiller and matrix.
Surface Modification by Electrical Discharge Machining of Sintered NdFeB Magnet
Authors: Li Li , Qi Li Ling , Zhai Xiao Qing , Wang Dong
Published: October 2010

In this study, the electrical discharge machining (EDM) of sintered NdFeB magnet was investigated. The surface characteristics were studied in terms of machining parameters. Correlation between the surface roughness, hardness, recast layer and the machining parameter were analyzed. Results show that an excellent machined finish can be obtained by setting the machine parameters at low pulse energy. Low pulse energy reduces the frequency of bursts of dielectric fluid and melt expulsions.
Study on the Green Remanufacturing of Ultrasonic Vibration Aided Hot-Dip Aluminizing and Micro Arc Oxidation
Authors: Niu Zong Wei , Li Zhi Yong , Wang F.F. , Zhang Jia You , Wang Ai Hong
Published: October 2010

In this paper alumina ceramic layer on worn stainless steel work piece was gotten using ultrasonic vibration aided hot-dip aluminizing and micro arc oxidation to realize green remanufacturing. Aluminum layer was gotten on the surface of stainless steel work piece using ultrasonic vibration aided hot-dip aluminizing method. The action mechanism of the hot-dip aluminizing process and the influence of ultrasonic vibration to hot-dip aluminizing process were studied and the best process parameters were achieved. Alumina ceramic layer of high hardness and wear resistance was achieved using micro arc oxidation method. The influence of current density to the characteristic of ceramic layer was investigated. The technology described in this paper can be used for the remanufacturing of worn stainless steel work piece.
Microstructure and Wear Resistance of the Composite Coatings Fabricated on Titanium Alloys by Laser Cladding
Authors: Zhang You Feng , Li Jun
Published: October 2010

In situ reaction synthesized TiB reinforced titanium matrix composites were fabricated using rapid non-equilibrium synthesis techniques of laser cladding. TiB/Ti composite coating was treated on Ti-6Al-4V surface using Ti and B powder mixture by laser cladding. Microstructure and dry sliding wear behavior of the in situ synthesized TiB/Ti composite coatings were investigated by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), energy-dispersive spectroscopy (EDS), hardness tester and friction and wear tester. The composite coatings consist of Ti, TiB and intermetallic compounds. The TiB reinforcement dispersed homogeneously in the composite coatings. The wear tests show that the friction coefficient and wear weight loss ratio of the coatings is lower than that of the Ti-6Al-4V alloy. The composite coating was reinforced by the in situ synthesized TiB ceramic particles. Based on the SEM observation, effects of scan speed on hardness and wear resistance of the laser cladding coatings were investigated and discussed.
Effect of Current Density on the Microstructure and Mechanical Properties of TiN/TiAlN Duplex Coating Deposited on SKH51 Steel
Authors: Du Ri Sheng , Peng Ji Hua , Liang Xian Wen , Tian Jun
Published: October 2010

In this paper, the TiN/TiAlN duplex coatings were deposited on SKH51 tool steel by means of multi-arc ion plating. By means of SEM, Vickers microhardness tester and scratch tester, the effect of target current levels on the surface morphology and mechanical properties of TiN/TiAlN duplex coatings on SKH51 tool steel was studied. During deposition, the effect of target current on microstructure and mechanical properties is responsible for the number, energy of emission target particles and distribution of target droplets. It was found that the thickness and microhardness of coatings, and the number of droplets with diameter more than 2 m increased with target current increasing. The adhesion force between coating and substrate reaches a peak value of 40.5N at 70A. From application view, it is better to control the Ti-Al target current density at 9.88x10-3 A/mm2.
The Investigation of Hot-Dip Aluminum and Micro-Arc Oxidation Multilayer Coating on 080A15 Steel
Authors: Zhao Zhi Long , Wang Jian Long , Liu Yan
Published: October 2010

By the combined process of hot-dip aluminum and micro-arc oxidation, multilayer ceramic coatings were obtained on the surface of commercial 080A15 steel plates. The microstructures and chemical elements of the coatings were investigated by means of scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS), respectively. The results show that the conversion coating on the surface of 080A15 steel plate is mainly composed of three layers, they are the outer layer of alumina ceramic coating, the middle layer of pure aluminum, and the inner layer of FeAl intermetallic compound. The FeAl intermetallic compound layer appears as branch-like to grow into the steel substrate. The alumina ceramic layer is a porous structure attached on the pure aluminum layer. The distribution of composition elements on the interface between the each layer is gradient transition, which is one of metallurgical adhesive characteristics.
Investigation of Deposition Mechanism and Characteristics of Electroless Sn Plating
Authors: Xu Rui Dong
Published: October 2010

A method for tin (Sn) film prepared by electroless plating on the surface of Cu substrate was realized, the silvery-white and semi-bright film has been obtained. The deposition mechanism is discussed and summed up period of replacement reaction, co-deposition period of Cu and Sn, and period of self-catalyzed deposition of Sn. The deposition process takes place because of the change of Cu and Sn potential when thiourea is added into the bath. That the film thickness increases linearly with the rise of plating times proves that the continuous self-catalyzed deposition of Sn has been realized, and the possibility of immersion plating is also excluded. The diffraction peak of Cu phase in the film becomes weaker and weaker, and that of Sn phase becomes stronger and stronger with increasing plating times. Additives B and C can play a role of grain refinement.
Study on Tribology Performance and Wear Controlling of 9Cr2Mo Steel
Authors: Jia Xiao Ming , Chai Jin Rong
Published: October 2010

9Cr2Mo steel is widely used as measuring and cutting tool steel. The friction and wear behavior of 9Cr2Mo steel was investigated under dry friction and solid lubricant by wear tester. The experiment results show that the friction coefficient of 9Cr2Mo steel is 0.34~0.58 under dry friction and 0.035~0.06 under solid lubricant. With the increase of load , the friction coefficient decreases and the wearing capacity increases under two kinds of conditions. The wearing capacity of 9Cr2Mo steel under solid lubricant is great lower than it under dry friction. The friction process is smooth under solid lubricant. It indicated that the solid lubricant took effect in antifriction and antiwear of 9Cr2Mo steel.
Liquid Film Performance Analysis of the Mechanical Seals with a Laser-Textured Micro-Pore Face
Authors: Yu Xin Qi , Liu Qing Gang , Gao Hui Qin , Yu Jia Hui
Published: October 2010

A theoretical model has been developed for the mechanical seals with a laser-textured porous seal face. By means of variable dimensionless steps, parametric analysis has been performed to obtain dimensionless liquid film pressure by the finite difference method. Liquid film pressure profiles over the pore column have be achieved by the computer program MATLAB. It is found from calculating results that average liquid film pressure increases with increase of the rotational speed, liquid viscosity and reduction of liquid film thickness. Hydrodynamic effect produced by micro-pores decreases with increase of fluid pressure. In addition, the effect of the pore area density and depth over diameter ratio on the liquid film pressure is very significant. Optimum values of these parameters can maximize the average liquid film pressure.
Microstructure and Properties of Laser Cladding Stellite 12/TiC/CaF2 Composite Coating on Copper Substrate
Authors: Wang Wen Yan , Dong Xiao Ming , Yan Hua , Xie Jing Pei , Wang Ai Hua
Published: October 2010

Stellite 12/TiC/CaF2 composite coating has been successfully fabricated on copper substrate by a pulsed Nd:YAG laser system with preplacment powder bed to improve the absorbance of copper substrate to laser energy. Microstructures, phases and wear properties were studied by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), dry sliding wear tester. The results showed that the existence phases of Co-based solid solution, Cr4Ni15W, TiC, Cr23C6, CaF2 and Ti8C5. The morphology of titanium carbide is mainly spherical and exists in two forms, one is TiC and the other is Ti8C5. The microhardness of the layers reveals a gradient variation along the cross section of the LSA layers. The friction coefficient of the coating is oscillating around approximately 0.17 because CaF2 is a solid lubricant because of the lamellar structure and softness and Titanium carbide is hard. The dry sliding wear testing shows the wear resistance of as-receive copper is significantly improved by laser cladding Stellite 12/TiC/CaF2 composite coating.
Experiment and Simulation of Laser Shock Processing on Fatigue Crack Growth of TC4 Alloy
Authors: Hua Yin Qun , Cai Zheng Rong , Chen Rui Fang , Chen Yu Xiao , Jiang Hui
Published: October 2010

The residual stress induced by Laser shock processing (LSP) can improve properties of fatigue crack growth. In this paper, the CT models of LSP and fatigue crack growth have been built. We experimented the TC4 alloy treated by LSP and fatigue crack growth and then simulated the fatigue crack growth. The results show that the values of simulations are conform to experiments. With the increment of peak pressures and overlapping rates, the fatigue lives have been increased, the fatigue crack growth rates have been descent. The fatigue lives have been 1.46-3.03 times compared with untreated by LSP, the fatigue crack growth rates have been 0.127-0.95 time compared with untreated by LSP, but to overlapping rates, it is not obvious with the improvement compared with peak pressures.
Effects of Immersion Time on the Electrochemical Impedance Spectroscopy Model of Epoxy Coating Modified by Nano-Sized Titanium
Authors: Zhang Xiu Zhi , Du Yuan Long
Published: October 2010

In this paper, the effects of immersion time on the electrochemical impedance spectroscopy model of nano-sized titanium modified epoxy coating immersed in 3.5(wt.%) sodilum chloride solution has been studied using electrochemical impedance spectroscopy(EIS). Through the analysis of the spectra of the coating at different immersion times, the results showed that the spectrum was different at the different immersion times. Therefore, the equivalent electrical circuit was varied with the increasing immersion time and there were the characteristics of the powder in the equivalent electrical circuits (electrochemical impedance spectroscopy model). By the study on the evlolution of impedance model in the given system, it was found that the nano-sized powder played an important part during the electrolyte diffusing to the surface of the substrate and the electrolyte reacting with the substrate
Effect of Laser Shock Processing on Fatigue Performance of 7075-T651 Aluminum Alloy
Authors: Chen Rui Fang , Jiang Hui , Hua Yin Qun , Chen Yu Xiao , Cai Zhen Grong
Published: October 2010

The effect of laser shock processing (LSP) on bending fatigue performance of 7075-T651 aluminum alloy was studied. LSP was performed on fatigue testing specimens with optimized parameters. Stress-life fatigue data were generated for both shocked and as-machined conditions. The fatigue improvements of LSP were discussed accounting for the effect of residual stress. The results show that shocked specimens exhibited significantly improved fatigue performance, with as-machined specimens having a factor of 1.6-4.4 improvement in fatigue life (depending on fatigue stress level). The stability of the residual stress induced by LSP under cyclic load was particularly investigated by means of X-ray diffraction measurements. Residual stress relaxation was observed. And the higher the cyclic load, the higher the relaxation rate. Due to the cyclic creep effect, the residual stress decreases linearly with the logarithm of the number of cycles.
Investigation on RE Ion Nitro-Carbonizing Technology Used for 4Cr5MoSiVl Casting Mold
Authors: Kuang Jian Xin , Wang Xin Heng , Liu An Min , Zhao Hu Jun
Published: October 2010

. In order to improve the high temperature stability of casting mold, we carried out the RE Ion nitro-carbonizing technology test on the 4Cr5MoSiVl steel. This test was done by using high-power pulsed supply for the 4Cr5MoSiVl steel casting mold surface treatment under different temperatures, time period, atmospheric pressure, and RE contents. The optimization of these parameters makes the layer structure dense, toughness increased, specifically the surface hardness, wear resistance, high temperature oxidation resistance, and thermal fatigue properties of the treated layer significantly improved. A test with the use of this technology has been done for the 4Cr5MoSiVl steel automotive lamp aluminum casting mold. The mold service life of each mold time increased from 30,000 to 100,000. The experimental results show that by using 4%RE 520oC×2h, and 1.05KPa atmospheric pressure, the treated layer has optimal qualities, which can meet the requirements in practice.
Friction and Wear Properties of Ti-6Al-4V Surface Modified by Nitriding-Mo Plating-Sulfurizing Composite Treatment
Authors: Wang Li Jie , Yang Jun Sheng , Xing Ya Zhe
Published: October 2010

A composite layer was prepared on the Ti-6Al-4V alloy surface by ion nitriding, magnetron sputtering Mo and ion sulfurizing composite treatment technique. The phase structure, morphology, and cross-sectional element distribution of composite layer were analyzed. Friction and wear properties of composite layer were tested by MM-200 laboratory tester. XRD analysis showed that the composite layer was mainly comprised of Ti, Mo, MoS2, TiN, and transition layer. This composite layer is perfect wear-resistant surface due to existence of self-lubricating MoS2 on hard Mo and TiN layers with good anti-friction ability. Thereby, the results of friction and wear test showed that anti-wear performance of Ti-6Al-4V alloy after composite treatment was remarkably improved under dry and sliding conditions. Both the friction coefficient and the wear loss of the nitriding-Mo plating-sulfurizing layers were lower than that of the nitriding layer due to the formation of the MoS2 layer on Mo and TiN layers.
Study on the Combined Anticorrosion Method of Thermal Spraying and Coating of Carbon Steel in Deposit Water of Storage Tank
Authors: Zhou Yong Zhang , Yang Chun Yan , Zeng Jian Min , Ni Xin , Chen Dong Sheng , Wei Wu Ji , Gu Bo Qin
Published: October 2010

Storage tank was protected from corrosion with the combined method of thermal spraying and coating, and corrosion resistance of the coating was studied through on-the-spot static weight loss method, potentiodynamic polarization curve and electrochemical AC impedance test. The result showed that the hanging slices with thermal sprayed aluminum powder, glass flake and epoxy resin coating had least weight loss and best corrosion resistance after 10 months of corrosion with on-the-spot weight loss experiment. In the polarization curve experiment, the anodic polarization curve of the hanging slices with thermal sprayed aluminum powder and glass flake had passivation characteristics, strong polarization area shifted left, weak corrosion current and greater polarization resistance. In the AC impedance spectra, hanging slices with thermal sprayed aluminum powder and glass flake had greater capacitive reactance arc and better corrosion resistance.
Study on Fretting Wear Behavior of 40CrNiMoA Steel
Authors: Li Zhu Jun
Published: October 2010

This study deals with fretting wear behavior of 40CrNiMoA steel on a SRVⅣoscillating friction and wear tester. The results indicate that with the frequency and load increasing, both the friction coefficient and fretting wear volume increase. With the amplitude increasing, the fretting wear volume increased too, but the effect of amplitude on friction coefficient was not simple positive correlation according to the experimental results. Meanwhile, the fretting wear mechanism is directly related to test frequency, load and amplitude. When they are small, the main fretting wear mechanism is abrasive wear, with these test parameters increasing, the main fretting wear mechanism turns to a combination of abrasive wear and adhesion wear. Based on the experimental results, the anti-fretting wear measures of steel worm gear pairs used in mechanical tracked regulator of tracked vehicle are discussed.
The Influences of Anticipated Heat Treatment on the Electroless Nickel Plating on Magnesium Alloys
Authors: Zhang Xiu Zhi , Li Ying Jie , Duan Xing Wang , Shao Ya Wei , Xiong Jun Bo , Liu Jian Sheng
Published: October 2010

In this paper, effects of anticipated heat treatment on the electroless nickel plating coated on magnesium alloys AZ91D were investigated by using heat treatments of solution (T4) and solution + aging (T6) before electroless nickel plating. The influence of anticipated heat treatment on the structure, composition and anti-corrosion property of electroless coating were studied by using Scanning Electrical Microscope (SEM), EDS and Corrodkote corrosion test. It is shown that compared with the as-casted magnesium alloys and samples treated with T4, the deposition rate of Ni, the P contained in the coating and the anti-corrosion property of samples treated with T6 are the highest for the given system studied, and T6 treatment can promote the anti-corrosion property of the coating effectively.
Numerical Analysis of Thermal Residual Stress in Diamond Film Deposited on Molybdenum Substrate
Authors: Liu Chang Long , Tang Da Pei
Published: October 2010

In order to solve the problem of diamond film crack when deposited on molybdenum substrate to improve the preparation quality of diamond film and the rate of finished products , the distributions of thermal residual stress components in diamond film and at interface between the film and molybdenum substrate were simulated by finite element method in the case of whether to consider the plastic deformation of molybdenum substrate or not, moreover, the influence of thermal residual stress upon the failure of film was analyzed. Results show that thermal residual stress is more coincidental with experimental data when the plastic deformation of molybdenum substrate is considered. There are large tensile radial stress and tensile axial stress in the vicinity of upper surface of the film, which is the primary cause for the film to crack.
Preparation and Process Optimization of Ni-Tl-B Coating with Fretting Damage Resistance
Authors: Song Dan Lu , Li Yan , Yang Ling Ling
Published: October 2010

Electroless plating technology used to alleviate fretting damage of titanium alloy was studied, Ni-Tl-B coatings were prepared, process optimization was worked out by the orthogonal table, deposition rate and solution consumption per hour and the initial friction coefficient and the bearing cycles under a low friction coefficient were chose as the index to calculate the range according to the economical efficiency and the application of coating under the surface morphology analysis and the fretting friction coefficient test, optimum process was finally worked out. Surface morphology was analyzed by TM-1000 scanning electron microscope and the fretting friction coefficient was tested by the DELTALAB-NENE fretting wear tester. The results shows that the surface morphology of the Ni-Tl-B coating are all typical cell structure which will be slightly different when the process changes and the optimum Ni-Tl-B coating has outstanding fretting damage resistance.
Research on Nano-Coating Absorption Application in Laser Processing
Authors: Yang Yang , Zhang Yang , He Tian
Published: October 2010

As more and more special refractory materials apply to laser processing technology, many processing problems have highlighted, this article studies on how to improve the laser absorption rate in the processing of work piece, and proposes the method of nanometers particles attached to improve absorption efficiency of laser materials before the laser processes smooth surface work piece materials, to analysis and forecast the theoretical effects[1]. Through the laser processing energy loss analysis and research, we can identify the major loss of laser processing means. Combined with the most commonly used laser processing smooth work piece surface pretreatment method deficiencies and some characteristics of nano-coating, nano-coating will focus on the process of laser processing to further improve the efficiency of heat absorption to provide a new way of settlement[2].
Effect of Rare Earth on Microstructure and Properties of the Self-Propagating Spraying Coating
Authors: Yue Li Xin , Hao Zhi Yong
Published: October 2010

The self-propagating spraying coating was prepared by Self-propagating High-temperature Synthesis(SHS). The effects of the rare earth(RE) on microstructure and the abrasive resistence of self-propagating spraying coating was investigated. The obve1rvations and analysis of the microscopic appearances of the worn surfaces of the coating were conducted by the use of SEM. The results showed: the RE can impove the properities of the self-propagating spraying coating, the suitable small amount(0.2%) of RE can refine the self-propagating spraying coating and improve the hardness and the wear resistence efficiently. When the excessive RE(0.5%) was added into the self-fluxing alloy power, the properties of the self-propagating spraying coating became worse.
Studies on the Growth Mechanism of Onion-Like Fullerenes by Arc Discharge in Liquid Benzene
Authors: Liu Wen , Meng Qing Sen
Published: October 2010

The growth mechanism of Onion-like fullerenes (OLFs) synthesized by arc discharge in liquid benzene was discussed. HRTEM was employed to characterize the morphologies and microstructures of the products. Results showed that the typical OLFs were highly crystallized with uniform diameter of 10-30nm. The growth of OLFs depended on the appropriate temperature gradient and quenching zone provided by the bubbles. The aromatic debris could act as graphite fragments composed of hexagonal carbon rings. The reducing of dangling bonds on the edges of graphite fragments would lower the energy of the system, resulting in formation of a close-caged structure at suitable temperature gradient by the auto-curling of graphite fragments. Based on the impact of the innermost core shape, such as C60 shape, quasi-spherical or polyhedral hollow concentric OLFs was formed. Adding ferrocene, ferrocene directly influenced the morphology and yield of OLFs.
Camouflage Coatings Design and Optimization of Construction Machinery
Authors: Shen Yue Guo , Dai Liang Liang , Zhang Nai Yan , Wei Guo Wei
Published: October 2010

Camouflage coatings method and its features are described. Concrete way of camouflage for construction machinery is presented. Aiming at the actual situation and in association with practical experiences, concrete methods to design and optimize camouflage for construction machinery are suggested.
Inline Rolling of 5182 Aluminum Alloy Strip Cast by a Vertical Type High Speed Twin Roll Caster
Authors: Nakamura Ryoji , Hanada Shuya , Kumai Shinji , Watari Hisaki
Published: October 2010

An inline hot rolling was operated on 5182 aluminum alloy strip cast using a vertical type high speed caster (VHSTRC) at the speed of 60 m/min. A porosity existing at center line of the thickness and a ripple mark on the surface, these are typical defects of the strip cast by the VHSTRC, could be improved by the inline rolling. The rolling speed was as same as the roll-casting-speed of 60m/min. The temperature of the strip, when the inline rolling was operated, was 450oC. The reduction of the strip of the inline rolling was 35%.
Roll Casting of Al-SiCp Composite Strip
Authors: Nakamura Ryoji , Nakamura Teppei , Nakamura Ryoji , Harada Hideto , Kumai Shinji , Watari Hisaki
Published: October 2010

Roll casting of Al-SiCp composite alloy strip was tried using a vertical type high speed twin roll caster equipped with mild steel rolls. The Al-20vol% SiCp and Al-30vol%SiCp alloy could be roll-cast to the strip. The casting speed was 30m/min. The thickness of as-cast strip was thinner than 2.5mm. The SiCp powder was dispersed uniformly at the thickness direction. The as-cast strip could be thin down to 1mm by the hot rolling and the cold rolling without broken.
Compaction Experiment on the Newly Designed Warm High Velocity Compaction Equipment
Authors: Tang Cui Yong , Xiao Zhi Yu , Chen Jin , Li Chao Jie , Ngai Tung Wai Leo
Published: October 2010

In order to develop high density powder metallurgy forming technology, a new concept combining high velocity compaction and warm compaction called warm high velocity compaction (WHVC) was presented. A new warm high velocity compaction forming equipment which adopts gravitational potential energy instead of hydraulic cylinder as hammer driver was designed. By means of the newly developed equipment, a preliminary study on warm high velocity compaction was performed. 316L stainless powder compacts with green density of 7.47 g/cm3 were obtained; the density is much higher than those prepared by conventional high velocity compaction. These results demonstrate that the newly designed equipment can basically meet the demand of warm high velocity compaction and the new forming method is superior to the conventional high velocity compaction. In addition, Densification mechanism of WHVC was also discussed.
Numerical Simulation of Forming Force in Tube Multi-Point Forming
Authors: Liu Qi Qian , Fu Wen Zhi , Li Ming Zhe , Chen Zhi Hong , Gong Xue Peng
Published: October 2010

Based on the finite element theory of dynamic explicit, the technology of multi-point forming was applied to tube forming. The process of tube multi-point forming was simulated by ABAQUS software. It is used to study the behavior of forming force under different wall thicknesses and materials for manufacturing tube. It has been found that when the curvature radius is set at 1.0m, the forming force gradually becomes larger as the wall thickness of the tube increases. The careful selection of materials is beneficial to controlling forming force. Due to the technology of mass scaling, the ultimate forming force is not the maximum forming force in the process of simulation forming. However, the ultimate forming force can be used to select the multi-point forming equipment.
Glass Forming Ability and Non-Isothermal Crystallization Kinetics of Zr64Al10.1Cu11.7Ni14.2 Metallic Glass
Authors: An Wei Ke , Cai An Hui , Luo Yun , Li Tie Lin , Li Xiao Song
Published: October 2010

The glass forming ability, thermal stability and non-isothermal crystallization kinetics of Zr64Al10.1Cu11.7Ni14.2 glass forming alloy were investigated. Its maximum glass forming dimension is up to 5mm and its critical cooling rate is less than 40Ks-1. The apparent activation energies derived from the Kissinger for Eg, Ex, Ep1 and Ep2 are 244.97±12.90, 264.63±10.18, 268.75±40.10 and 222.34±24.12 KJmol-1, respectively. The fragility parameter m is about 20.27, indicating its better thermal stability and glass forming ability.
Corrosion Behavior of Cu60Zr30Ti10 Amorphous Alloy
Authors: Cai An Hui , An Wei Ke , Luo Yun , Li Tie Lin , Li Xiao Song
Published: October 2010

The ribbon samples for Cu60Zr30Ti10 (at. %) with a thickness of 50 μm and a width of 13 μm were prepared by melt spinning at the wheel speed of 30 m/s. The glassy structure was confirmed by X-ray diffraction (XRD) using Cu Kα radiation. The corrosion property and corrosion mechanism in 1 M HCl, 1 M NaCl, and 0.5 M H2SO4 solutions were investigated by electrochemical polarization measurement. The corrosion mechanisms are dominated by the pitting corrosion in H2SO4 solution and the pitting and uniform corrosion in HCl and NaCl solutions. In addition, the corrosion resistance in H2SO4 solution is better than that in HCl and NaCl solutions. Cu60Zr30Ti10 glassy alloy in H2SO4 solution is nobler than in HCl and NaCl solutions.
Experimental Research on Strain Distribution Characteristics of Thin-Walled Rectangular Tube in Rotary-Draw Bending
Authors: Tian Shan , Liu Yu Li , Zhao Gang Yao , Yang He
Published: October 2010

The rotary-draw bending process of thin-walled rectangular tube is a complex process with large deformation, large displacement and finite strain which makes the defects, such as wrinkling, distortion and crack be easily produced. To study the complex plastic deformation characteristics of thin-walled rectangular 3A21 aluminum tube during rotary-draw bending, the distributions of tangential, circumferential and normal strain have been studied by experiment using grid method. The results show that the maximum value of three-direction strain appears in the ridges of rectangular tube and tangential strain is the maximum principal strain. The value of maximum tangential tensile strain is lager than the maximum tangential compressive strain; it is the reason why crake is prone to occur during rotary-draw bending. The strain distribution curve along bending direction is not completely symmetrical with middle cross-section. With the increase of bending angle, three-direction strain of tube also increases and circumferential strain increases relatively smaller.
Study on Pressurizing Velocity and Model of Vacuum Counter-Pressure Filling Process
Authors: Yan Qing Song , Yu Huan , Xu Zhi Feng , Xiong Bo Wen , Cai Chang Chun
Published: October 2010

During filling process of vacuum counter-pressure casting, the pressurizing velocity is one of the most important parameters, and it affects whole filling process of molten metal and the quality of castings, the pressurizing velocity must be reasonably controlled and chosen. Through analyzing the pressurizing velocity of vacuum counter-pressure casting filling process, the results show that pressurizing velocity is related with absolute temperature of down kettle gas, radius of rising tube, initial volume of down kettle, height from original position of molten metal to top of rising tube and gas flux. When other conditions are same during filling process of vacuum counter-pressure casting, pressurizing velocity is proportional to gas flux, and it is linear. Meanwhile, through experimental verification for relationship of pressurizing velocity with gas flux, their actual relationships and mathematical models are obtained, and correction coefficient is determined at the range from 0.95 to 0.98.
A Self-Assembly Approach to Fabricate Bi2S3 Nanorods
Authors: Huang Yang Feng , Cai Ye Bin , Liu Hao
Published: October 2010

Bismuth sulfide (Bi2S3) nanorods were successfully fabricated by sonochemical aqueous solution. The morphology, crystallinity and composition of samples at various growth stages were investigated by transmission electron microscopy (TEM), selected area electron diffraction (SAED) and X-ray diffraction (XRD). The results showed that the Bi2S3 nuclei had an obvious tendency to arrange themselves in rod-like arrays over extended length scales under soft template. Moreover the crystallinity would be reinforced with the elongation of the aging periods. The growth mode of particle−to−particle by self-assembly under soft template was proposed. The band gap energy of Bi2S3 nanorods was estimated at about 1.36 eV by UV-Vis absorption spectroscopy.
Application of Ductile Fracture Criterion in Hot Forging Damage of Mn18Cr18N Steel
Authors: Duan Xing Wang , Zhang Xiu Zhi , Wei Xin Peng , Liu Jian Sheng , He Wen Wu , Tian Ji Hong
Published: October 2010

In this paper, the hot forging behavior of Mn18Cr18N steel is studied based on the viewpoint of meso-damage. According to high temperature tensile stress - strain curve of Mn18Cr18N steel under different temperatures, the relationships of void initiation strain and fracture strain with deformation temperature are obtained. The temperature dependence of damage threshold is obtained at 950°C~1200°C for Mn18Cr18N steel by Cockcroft & Latham criterion, That is, Ci,f value increases monotonously with temperature increasing. The corresponding deformation amounts of void initiation and fracture appearing are predicted accurately by combining Cockcroft & Latham criterion with finite element analysis during hot forging of Mn18Cr18N steel, which is in good agreement with the actual production. Under these experimental conditions, once upsetting deformation amount should be controlled in 50% based on hot upsetting test and finite element simulation. These provide theoretical instruction for preventing forging cracking of Mn18Cr18N steel.
Hot Deformation Behavior of 316LN Stainless Steel
Authors: He Wen Wu , Liu Jian Sheng , Chen Hui Qin , Guo Hui Guang
Published: October 2010

Hot-compression experiments of 316LN stainless steel have been conducted on a Gleeble-1500D thermal-mechanical simulator. We have analyzed the flow stress-strain curve and acquired the constitutive equation of 316LN steel by calculating stress exponent, activation energy and Zemer-Hollomon parameter. Then, based on the material model theories and Prasad instability criterion, the iso-efficiency map at strain 0.6 of 316LN steel has been developed. The larger power dissipation rate is emerging at 1050~1200°C and lower strain rate. In addition, we have also analyzed the hot deformation microstructure mechanism of 316LN steel is discontinuous dynamic recrystallization by the observation of deformation microstructure. These results have been of great significance to understand microstructure evolution and to determine the optimum hot-working conditions in the production.
Deformation Behaviors of AZ31B Magnesium Alloy Sheets in Hydraulic Deep Drawing
Authors: Yang Lian Fa , Yi Liang , Mao Xian Chang , Chen Guo
Published: October 2010

Magnesium alloy sheets have poor formability at room temperature, and the hydraulic forming may be a choice to improve its formability. Experiments were conducted to investigate the deformation behaviors of AZ31B magnesium alloy sheet in radial pressure deep drawing, one of the hydraulic forming technologies. The influence of hydraulic pressure, die dimension, blank dimension on the limit drawing height (LDH) of the drawn workpieces is investigated, and the location, evolvement and pattern of the fractures are also analyzed. The research results show that the obtained LDH increases with the hydraulic pressure when the punch corner radius is large enough, the formability can be improved only under a proper moderate hydraulic pressure when the punch corner radius is small; moreover, the location of the fractures may be around the corner, on the flange and the sidewall of the drawn workpieces, which appears different evolvement directions and patterns through cross-section.
Study on the Technological Adaptability of the Reclaimed Sand Applied in the Chemical Bonded Sand
Authors: Sun Qing Zhou , Xu Rong Fu , Zhao Zhong Kui , Zhang Pu Qing , Liu Wei
Published: October 2010

The technological adaptability of the reclaimed sand applied in the chemical bonded sand was studied in this paper. The reclaimed sand can be obtained by the process of high-temperature baking followed by mechanical reclamation and separation of micro-powder. The reclaimed green sand which containing different types of chemical bonded core sand were applied in corresponding system of chemical bonded sand process, such as the process of cold-box sand, hot-box sand, precoated sand, sodium silicate sand and self-hardening sand. Through technological experiments, it can be found that the tensile strength value of the precoated sand and sodium silicate sand which were prepared using reclaimed sand can be equal or slightly higher than that of prepared using the base sand, the tensile strength value of the cold-box sand, the hot-box sand and the self-hardening sand which was prepared using the reclaimed sand are lower than that of prepared using the base sand. Compared with the chemical bonded sand requirements in the foundry practice, the cold-box sand, the hot-box sand, the precoated sand which was prepared using the reclaimed sand can still meet the casting process needs, but the self-hardening sand which was prepared using the reclaimed sand cannot meet the casting process needs.
Effect of Different Processing on Properties of Silica Sand
Authors: Sun Qing Zhou , Xu Rong Fu , Zhao Zhong Kui , Zhang Pu Qing , Liu Wei
Published: October 2010

This paper will cover some processing routes along with grading and physical/chemical attributes of silica sand. The silica sand in this experiment was divided into four lots, and each of them was processed by the methods of calcining, scrubbing, mulling or rubbing respectively. The test results show that the sand grains which processed by different processing methods are irregular, the acid demand value of sand is lower than that of the base sand, and the grain size distribution of sand is similar to that of the base sand. However, the SiO2 content of processed sand is increased, the impurities content has a downward trend. Compared with the base sand, it can be found that the tensile strength value of molding sand prepared using the processed sands is higher and the bench life is almost no change.
Study on Accuracy Improvement of Vehicle Crash Simulation Considering Stamping Effects
Authors: Du Han Bin , Ye Ping , Wang Da Zhi , Tang Xiao Dong
Published: October 2010

It is general preferable to consider stamping effects of sheet metal forming for vehicle crash simulation nowadays. However, the present approaches for stamping simulation and coupling forming results to crash finite element model require massive pre-works. To overcome these difficulties, an inverse method for rapid and simple stamping simulation using HYCRASH is introduced, where crashworthiness analysis of front side rail under frontal crash was used as an example in this study. A detailed stamping simulation by AUTOFORM is used for comparison, also accompanied with the one without stamping effects. Through comparison of stamping results and frontal crashworthiness performance, it is concluded that effective plastic strain makes more contribution on simulation accuracy than thickness reduction, and HYCRASH shows an attractive approach for stamping analysis than AUTOFORM coupled in crash simulation in the context of computational cost.
Experimental Study on Influencing Factors to Drive Line of Box-Shaped Part with Curved Bottom
Authors: Hu Xiu Li , Yang Nan , Xing Zhong Wen
Published: October 2010

Drive line is the surface defect on the automotive panel. In order to investigate the causes and control methods of the drive line, the box-shaped part with curved bottom was designed based on the shape characteristics of automobile panel. Then this part was taken as an experimental model to analyze the causes and forming process of the drive line on its surface. Finally, influencing laws on the drive line from the draw bead, the important forming process parameter, were obtained by the experiments. The results showed that the draw bead has great impact on the drive line. Different setting ways of the draw beads can make good control for the formation, displacement and its direction of the drive line. Besides, it is an important way for setting the draw beads properly to prevent the stamping parts from the formation of the drive line.