bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Various Pretreatment Methods of Inoculum on Biohydrogen Production
Authors: Wang Yuan Yuan , Wang Jian Bo , Hu Cheng Xiao , Zhang Yan Lin
Published: November 2010

Influence of different pretreatment methods applied on anaerobic mixed inoculum was evaluated for selectively enriching the hydrogen (H2) producing mixed culture using glucose as substrate. The cumulative H2 yield and H2 production rate were found to be dependent on the type of pretreatment procedure adopted on the parent inoculum. They could be increased by appropriate pretreatment methods, including use of heat, alkaline or acidic conditions. Along with the processing temperature and time of heat pretreatment and alkaline of alkali pretreatment increasing, the H2 yield increased and then declined, but it declined and then increased as the acidity of acid pretreatment increasing. Among the studied pretreatment methods, the heat pretreatment methods procedure enabled higher H2 yield and the maximum H2 production rate, then were alkali and acid pretreatment methods. When the inoculum was heat-treated at 80°C for 30 min, the highest cumulative H2 yield was obtained at 2152.0 mL, which was 53.20% higher than the control, and the maximum H2 production rate was 178.0 mL h-1, which was 122.0% higher than that of the Ctrl (138.0mL h-1).
A Novel Structure Design of Conductive and Magnetic Electromagnetic Shielding Composites
Authors: Qu Zhao Ming , Wang Qing Guo
Published: November 2010

Regarding to the special requirement of electromagnetic shielding materials, the concept and connotation of conductive and magnetic electromagnetic shielding composites were presented and the requirement causes of this kind of electromagnetic shielding composites applied in military and civil areas were analyzed. A structure design of new-type electromagnetic shielding materials is presented and the feasibility of the design was analyzed by associating with modeling method and optimization method.
Experiment on C40 Machine-Made Sand Concrete with Combined Admixture of Limestone Powder and Substandard Fly Ash
Authors: Xu Guo Qiang , Qiao Lan , Liu Juan Hong , Wang Xiao Lun
Published: November 2010

The combined admixture of limestone powder and substandard fly ash for the preparation of C40 machine-made sand concrete were studied. The results show that the C40 machine-made sand concrete prepared with the combined admixture of limestone powder and substandard fly ash has very good workability, with a 60min slump loss of less than 15mm. The combined admixture of limestone powder and substandard fly ash has very good filling effect and crystal nucleus effect, which makes hardened cement paste structure and interface structure more compact. The chloride ion permeability coefficient of machine-made sand concrete at 28d are less than 182×10-14m2/s, showing that the C40 machine-made sand concrete has good resistance to chloride ion permeation. It can be seen from SEM and energy spectrum technique that the structure of machine-made sand concrete is compact, and the C-S-H gel in the concrete has low calcium-silicate ratio.
Research on the Interface of Infiltration Brazed Tungsten Carbide Composite Cladding
Authors: Yan Jian Wu , Li Pei Pei , Cao Qing , Liu Ying , Lu Quan Guo , Cao Qing Hua
Published: November 2010

WC-Ni-Cr composite cladding is fabricated on the Q235 steel by infiltration brazed in a vacuum furnace. Microstructure of interface and welding specimen's longitudinal section of alloy coating are investigated by CMM-88E metallographic microscope and FEI Quanta200 scanning electron microscope. Element diffusion and distribution along the longitudinal section are tested by the Energy Disperse Spectroscopy (EDS), produced by Oxford Corporation; Influencing factors of the coating's brazed interface are analyzed. The results show that when nickel base coating powders are used for infiltration brazed, the BNi-2 solder is appropriate and the appropriate temperature should be in 1120~1140 °C. The welding interface of vacuum brazing compact very well and the existence of element diffusing forms the metallurgy welding contact surface.
Study of VOC-Free, No-Clean Flux for Lead-Free Soldering in Electronic Packaging
Authors: Xu Dong Xia , Wang Dong Bin , Lei Yong Ping
Published: November 2010

Aiming at issues existed in lead-free electronic packaging, as well as the air pollution induced by volatile organic compounds (VOC) in conventional soldering fluxes, a new VOC-free no-clean flux was formulated specifically for lead-free wave soldering. Spread test and wetting balance test were carried out to evaluate the activity of the newly developed flux with Sn3.8Ag0.7Cu lead-free solder. Besides, influence of flux residues on corrosivity and reliability of printed circuit board (PCB) was investigated by measurement of surface insulation resistance (SIR). The results showed that VOC-free fluxes required a good preheat process to obtain better soldering performance. And, flux residues of new VOC-free 1 had higher corrosivity than VOC and VOC-free 2, so the flux formulations needed to be ameliorated for the future. Due to the benefits of eco-friendly and cost saving, it is promising to successful implementation of VOC-free fluxes if some process modification is done.
Numerical Analysis of the Multi-Point Stretch Forming Process of Aircraft Outer Skin Part
Authors: Wang Shao Hui , Cai Zhong Yi , Li Ming Zhe , Lan Ying Wu
Published: November 2010

As a flexible manufacturing technique, Multi-point stretch forming (MPSF) is a suitable method for forming aircraft outer skin part. The traditional solid stretching die is replaced by the discrete multi-point die (MPSD), and the sheet metal is stretch-formed over the MPSD generated by serial adjusting mode or parallel adjusting mode. The MPSF can be used to form the parts of different shape and reduce the cost and leading time of stretching die fabrication for aircraft outer skin part. A series of numerical simulations on typical MPSF processes of aircraft outer skin part were carried out. The thickness of elastic cushion and free length are important factors to influence on the stretch forming results of stretch-formed parts. The numerical simulation results show that the thicker the elastic cushion is, the more valid the dimple will be suppressed .The longer the free length is, the easier the wrinkle will be brought.
Tests on High-Velocity Forming of AZ31 Magnesium Alloy by Explosive-Impulsive Pressure（Part I）
Authors: Ruan Li Qun , Hokamoto Kazuyuki , Marumo Yasuo , Yahiro Ititoku
Published: November 2010

As reported in the previous report, increasing velocity by high-speed impulsive energy could improve the formability of AZ31 magnesium alloy. The improvement of ductility of AZ31 magnesium alloys can be observed, which is difficult to observe in usual cold forging techniques. This paper (Part II) is a coutinuation of the reported work in the previous paper. The forming of the AZ31 casting magnesium alloy was done. The hardness distribution of the test specimen was investigated for each experiment, and the microstructures are analyzed. The microstructural results indicate that adiabatic shear bands are formed and the microstructure is changed by the formation of huge amount of fine grained recrystallized structure. Furthermore, solid state is retained in the materials as well as the surface. [1]
A Novel In Situ Roughness Measurement Based on Spatial Average Analysis of Binary Speckle Image
Authors: Hsu Kuo Chan , Fuh Yiin Kuen
Published: November 2010

This study proposes a novel optical technique and method for in-situ roughness measurement. The speckle image was obtained by illuminating a laser beam and the reflected laser pattern image from a surface was binarizd and examined. The intensity distribution of binary image utilizes the combined effects of speckle and scattering phenomena. A new parameter of intensity distribution of binary image, Sd BD has been proposed and the surface roughness parameter Ra of machined surfaces (ground) were correlated experimentally. Measurement results demonstrate an excellent correlation between the SdBD and Ra with correlation coefficient of 0.9706. The practicality of the proposed method to in-situ roughness measurement was applied to six samples from roughness Ra 0.2 to 6.25μm (0.3 λ and 10 λ, where λ is diode laser wavelength) of steel through grinding process.
Influence of Electron Beam Pulsed Times on the Properties of 40Cr
Authors: Chen Yuan Fang , Peng Xiao Dong , Hu Jian Jun , Xu Hong Bin , Hao Chan
Published: November 2010

Surface modification of 40Cr steel by high current pulsed electron beam has been investigated . The pulsed times of HCPEB was changed from 1 to 25 to prepare different specimens. Surface microstructures and section microstructures after HCPEB irradiation were detected by using metallurgical microscope, SEM and X-ray diffractometer. It is shown that crater defects were found on the surface after the irradiation of HCPEB and the density of craters will decrease with increasing pulses times. When treated by 27Kev accelerating voltage, with increasing pulse times, the particles located in surface layer were obviously refined .The surface roughness, hardness, wear properties and corrosion resistance were analyzed after irradiation of HCPEB. The wear resistance and corrosion resistance were obviously enhanced after 10 pulses treatment.
Cycloidal Rotary Indexing Compound Locus Numerical Control Machining Technology Based on SIMENS840D
Authors: Chen Xin Chun , Li Jia
Published: November 2010

Based on the functional features of SIEMENS840D, a plan to realize the machining technology with cycloidal rotary indexing compound locus is provided. The machining principle with cycloidal rotary indexing compound locus method is stated at first, in which technological requirements for numerical control system are determined. Then, in combination with the functional features of SIEMENS840D, the overall structure of numerical control program produced with cycloidal rotary indexing compound locus, as well as the detailed parts of the program are proposed. Finally, the feasibility of the plan is verified with a machining example.
Effect of Diamond Film's Thickness on Thermal Residual Stress after Considering the Substrate's Plasticity
Authors: Liu Chang Long , Tang Da Pei
Published: November 2010

Thermal residual stress in diamond film deposited onto Mo substrate was simulated and analyzed comprehensively by using the finite element method on condition that the substrate’s plasticity was considered. The contour plots of the stresses were described. Moreover, the effect of the film’s thickness on thermal residual stress was investigated. The results show that every stress component in the film has the remarkable stress concentration at the intersection of the interface and the side of the film. The location of maximum tensile principal stress in the film is at the upward face or side face of the film or the interface. The magnitude of maximum tensile principal stress increases when the film becomes thicker. These conclusions are useful to the proper choice of the film’s thickness and the effective control of the stresses during preparation of diamond film.
Research about Techniques of Chinese Traditional Architectural Stone Carving
Authors: Li Xu Hong
Published: November 2010

This paper discusses the artistic processing techniques of Chinese traditional architectural stone carving, and describes the classification of stones, procedures of processing technology, transformations of artistic style in the development of the society, as well as comparisons of the style of the architectural stone carving between central plains and Guangdong Chaozhou and Shantou areas, formations of local characteristics and evolutions of each historical period. This paper also probes into the artistic processing techniques and esthetics of Chinese architectural stone carving, and initiates people to have profound understanding to the artistic values of Chinese traditional architectural stone carving, in order to provide references in modernization strategy, and enable new development of artistic processing of modern architectural stone carving.
Numerical Analysis on Tribological Properties of Mechanical Seals with a Laser-Textured Face
Authors: Yu Xin Qi , Peng Pei Ying , Gao Hui Qin , Yu Jia Hui
Published: November 2010

An analytical model is developed to study the effects of operation conditions and micro-pore geometry parameters on the friction performance of the mechanical seals with a laser-textured micro-pore face. Seal opening forces at various operation conditions and micro-pore geometry parameters are obtained from the solution of the Reynolds equation by the finite difference method. A derivative expression of the friction torque of the mechanical seals with a laser-textured micro-pore face is calculated and contributing factors of the friction torque are analyzed. It is shown that fiction torque increases with increase of the rotating speed. An optimum pore size that corresponds to minimum friction torque is found and is consistent with experimental results.
Influence of Radial Load on PEEK Plastic Bearings Life Cycle
Authors: Koike Hitonobu , Honda Takashi , Kida Katsuyuki , Santos Edson Costa , Kashima Yuji , Kanemasu Kenji
Published: November 2010

Nowadays, due to strict environmental requirements, the automotive industry has been reducing vehicle weight in order to minimize the CO2 emission. This had led to an increase in the demand for plastic car parts as a replacement for formerly metal components. Poly ether-ether-ketone (PEEK) has a high glass transition temperature of 143°C, good friction and heat resistance, and can be easily machined. Due to these characteristics, PEEK is already being widely applied in the production of various car parts, such as seat adjustment parts, transmission parts, oil-pump parts etc. In the present study, PEEK bearings were produced by machining and their rolling contact fatigue (RCF) under non-lubricated conditions was investigated. Under high radial load, seizure in the inner bearing part occurred while under low radial load, there was failure by adhesive wear. Exposed to medium load between 85.6N and 93.1N, however, the bearings achieved relatively long lives of over 1.0x10E6 cycles, as well as a unique feature of self-lubrication that rid the raceway of micro depressions, deposits or smearing.
Effect of Aluminum Addition to Cu-10wt%Sn Bearing on its Pin-on-Disc Wear Behavior
Authors: Chobaomsup Viriyah , Tachai Luangvaranunt
Published: November 2010

The objective of this research was to study effect of sintering time, sintering temperature and aluminum addition on pin-on-disc wear behavior of Cu-10wt%Sn bearing that was produced from powder metallurgy method. It was found that, for the as-sintered samples, the larger addition of aluminum, the greater reduction in density and hardness in all sintering conditions. Density and hardness of samples sintered at 900°C decreased with increasing sintering time. Density and hardness of samples sintered at 830°C increased with increasing sintering time. Maximum hardness was obtained when the samples were sintered at 900°C for 30 min or sintered at 830oC for 60 min. Heat treating the samples by annealing at 750oC for 1 h, and quenching in water improved the hardness of the samples alloyed with aluminum significantly. Hardness of 5wt%Al sample increased by 37% to 69.2 HV. Wear mode of samples without aluminum addition was abrasive with accumulation of α-phase wear debris on worn pin surface. For samples with aluminum addition, wear mode was abrasive-oxidative producing clean worn surface which was preferred for self-lubrication mechanism of this type of bearing.
Parameters' Correlation Analysis Based on Gaussian Process for Injection Molding
Authors: Xia Wei , Zhang Sheng Hua , Liao Xiao Ping , Yan Xue Lian
Published: November 2010

Based on Gaussian process (GP), a new parameters’ correlation analysis method for injection molding is proposed. Referred to the design idea of canonical correlation analysis (CCA), GP is used to extract accurate canonical correlation variables simultaneously from two data sets. And then the canonical correlation variables are used to analyze the correlation between parameters and design objectives. The cross member under windshield of a van is taken for a case. For the weld lines defects produced in injection process, the correlation of process parameters is analyzed to identify which parameters are more related to weld lines. The validity of this method is proved by the optimal result. And this provides strong theory and feasible algorithm for adaptive intelligent optimization and controlling of the parameters in injection process.
Thermal Errors Simulation and Modeling of Motorized Spindle
Authors: Cui Liang Yu , Zhang Da Wei , Gao Wei Guo , Qi Xiang Yang , Shen Yu
Published: November 2010

Thermal errors of motorized spindle are of great importance to affect final machining precision of CNC machine tool. Thermal characteristics simulation analysis of motorized spindle is realized by ANSYS; thermal errors test measurement is completed based on 5-point method; and prediction models of thermal errors are constructed by multiple linear regression (MLR) method, Back Propagation (BP) neural network method and Radial Basis Function (RBF) neural network method respectively. The results of simulation and experiments illustrate that simulation results can represent thermal characteristics of motorized spindle, whose degree of confidence mainly depending on setting of thermal load and boundary conditions properly or not; RBF neural network model has highest prediction precision for thermal errors of motorized spindle based on test data.
Experimental Study on the Reheating Process for A356 Alloy in Thixoforming
Authors: Tang Pei , Yao Zhe He , Zhou Hong Hua , Sun Zhuo Xiong
Published: November 2010

The induction heating of the billets is a critical step in the thixoforming process. To improve the quality of thixoforming, the induction heating strategy should be investigated. In this study, by using an induction heating system of 50 kHz, multi-step reheating schemes were adopted to reheat the nondendritic A356 alloy to the temperature between the solidus and liquidus line. To obtain uniform temperature distribution and fine globular microstructure, the effects of the reheating parameters, such as reheating time, reheating temperature, holding time and holding temperature, were investigated. Then the analysis of the final temperature difference and the optical microstructure of the reheated billets were conducted, the results showed that two-step reheating process is suitable for A356 alloy with the size of 45 mm × 25 mm, and the suitable time for the final holding process is 2 min.
Analysis of a Tool System with a Four Axes Flexible Fixture
Authors: Huang Hung Ying , Fuh Kuang Hua , Wu Jung Shu
Published: November 2010

This study is to develop a tool system, which is formed by a series of procedures, modifications, and assemblies, and to learn how processing characteristics are affected and what various processing parameters are. According to the cutting tool compressibility and clamping devices of rigidity and flexibility, three distinct combinations are as follows, that is (1) rigid clamping devices with hard cutting tools, (2) flexibile clamping devices with hard cutting tools, and (3) rigid clamping devices with soft cutting tools. The first are generally cutting processes, while the second are polishing processes and the third produce milling wipe or grinding and polishing compound processes. The cutting part is quite different and may cause different accuracy and removing rate. The mixture processes, such as turn-burnishing, milling-burnishing and grind-polishing, are existed. If certain flexible clamping devices with hard cutting tools are formed, the most suited to this process will be practical benefits. Considering the flexible cutting tools of clamping devices are less systematically designed, this study would mainly focus on the establishment of a systematic design, and actual cutting to explore its applications. In order to take into account the characteristics of flexibility and reduction of the retardation when connected, meanwhile, to meet not only the fixture complexity and availability (being easy) to manufacturing, but also to fit the strength and processing requirements, the systematic design is to create a tool system. After some cutting experiments have been conducted, the results proved that different degrees of flexibility on the workpiece surface would lead to different degrees of accuracy.
Study on the Friction and Wear Properties of Yttrium-Stabilized Zirconia Based Nanocomposite Ceramic Tool and Die Materials
Authors: Xu Chong Hai , Wu Guang Yong , Zhang Yong Lian , Zhang Rong Bo
Published: November 2010

Based on the requirements for ceramic materials of cutting tool and die and the aim of improving comprehensive mechanical properties of ceramic tool and die materials, nanocomposite ceramic tool and die materials with high mechanical properties were fabricated successfully with nanometer composite method. Friction and wear properties of the developed ZrO2/Ti(C7N3) nanocomposite ceramic tool and die materials were experimentally studied in detail. Morphologies of the worn surfaces were observed and analyzed by ESEM. Wear mechanisms of nanocomposite ceramic tool and die materials were discussed with comparison with that of single-phase ZrO2 ceramics. It indicates that wear mechanisms of ZrO2/Ti(C7N3) nanocomposite ceramic tool and die materials are mechanical cold welding, abrasive wear and adhesive wear.
Microstructure and Properties of Ni-Base Coatings Obtained by Micro-Plasma Arc Cladding Processes
Authors: Xia Dan , Xu Bin Shi , Lv Yao Hui , Jiang Yi , Liu Cun Long
Published: November 2010

Microstructure and properties of Ni-base coatings obtained by micro-plasma arc cladding was investigated. A uniform clad coating was obtained after optimizing the cladding parameters by using NiCrBSi powder. Microstructure of the coatings observed by optical and scanning electron microscopy (SEM) indicated a homogenized microstructure. It has no evident heat-affected zone and no porosity. The phase of the coating was formed by γ-N solid solution, nickel boride Ni3B, carbide Cr21.34Fe1.66C6 and Cr2B3 type chromium boride. Although it likes the laser cladding coatings, micro-plasma coatings has its own characteristic. In addition, the average microhardness and nanohardness of coatings which were much higher than the substrate were observed, and the distribution of the microhardness was drawn.
Research and Application Status of Arc Welding Heat Source Model for T-Joint Numerical Simulation
Authors: Jia Li , Zou Yong , Zou Zeng Da , Zhao Yong Sheng , Yao Qu Shi
Published: November 2010

During numerical simulation of welding process, the temperature field simulation is fundamental for simulating other issues of welding process, and establishing the heat source model is the most basic work for temperature filed simulation. Based on the analysis and induction of arc welding heat source model used in T-joint welding simulation, points out the existing problems and future development direction of heat source model for T-joint, provides a reference for further research and practical application.
Effect of Chromium Nitride on Microstructure and Properties of Fe-Based Coating by Laser Cladding
Authors: Li Gui Hua , Zou Yong , Zou Zeng Da , Li Xiao Nan
Published: November 2010

In this paper, the Fe-based cladding layer was prepared on 42CrMo substrate by laser cladding mixture containing chromium nitride. The effects of chromium nitride on microstructure and property of cladding layer were studied. The experimental results indicate the chromium nitride is unstable during the process of laser cladding. It is very difficult to obtain chromium nitride in the laser cladding layer. However, the addition of chromium nitride in cladding powders could promote the formation of austenite phase, and increase the microhardness of cladding layer. The reason about increasing the microhardness of cladding layer is the formation of little carbide and solution strengthening of nitrogen, not the strengthening from chromium nitride.
Comparable Study on Water Cavitation Peening and Traditional Shot Peening of Almen Strips
Authors: Zhao Xiu Juan , Wang Jun Wen , Chen Chun Huan , Sun Yuan , Ren Rui Ming , Ju Dong Ying
Published: November 2010

Comparing with conventional mechanical shot peening (SP) technique, water cavitation peening (WCP) experiments of Almen strips were carried out on a self-manufactured equipment. The results show that WCP demonstrates a wide range of standoff distance (SD) that from the nozzle to the surface of the object. By measuring the colour changes of the Fuji pressure sensing film, over 110 MPa impacting pressure was detected, which is resulted from the bubbles blasting on the sample surface when the SD is from 65 to 100 mm under 40 MPa of operating pressure. 600 MPa compressive residual stress achieved on the suface of the Almen strips after WCPed for 32 min. The depth of the zone affected by the compressive residual stress is about 100 µm. The highest residual stress appears in the top surface layer, while in case of SP it appears in the subsurface. Compared to SP, WCP is capable to get rather smoother surface and cause less deformation of the testing sheet, simultaneously.
Influences of Variable Friction Coefficient on the Hot Formability of Ultra High Strength Steel Sheet
Authors: Yu Hai Yan , Bao Li , Deng You Zhi , Cao Wei
Published: November 2010

Friction coefficient is an important parameter in sheet metal forming especially in hot forming. Friction condition not only influences material flow but also affects the thermal conductivity between blank and tools. In this study, varied friction coefficient is introduced to the hot forming simulation of B-pillar made of ultra high strength steel sheet 22MnB5. Three curves of friction coefficient vs. temperature are investigated. All of the heat transferred by conductivity, radiation and convection are considered in the simulation. And the temperature-dependent material and process parameters are supplied. It is demonstrated that the coupling effect among the strength and hardness of the metals, the properties of the oxide film covering blank surface and viscosity of the lubrication oil leads to the fact that the friction coefficient changes with temperature instead of constant during hot forming. The friction coefficient curve characterized by increasing first then decreasing gives the best simulation results and then is followed by the one which is characterized by decreasing first then increasing. The constant friction coefficient is the last.
Numerical and Experimental Investigation of Pulsed Laser Welding of Hastelloy C-276 Alloy Sheets
Authors: Guo Yu Quan , Guo Dong Ming , Ma Guang Yi , Wu Dong Jiang
Published: November 2010

In this paper, a three-dimensional finite element model is developed to compute thermal phenomena of 0.5 mm thick Hastelloy C-276 alloy sheets during pulsed laser beam welding (PLBW). Temperature-dependent thermal properties of Hastelloy C-276 alloy, effect of latent heat of fusion, and the convective and radiative boundary conditions are taken into account in the model. The space-time temperature distributions in a butt-joint weld produced by the PLBW process are predicted from the beginning of welding to the final cooling. The heat input to the model is assumed to be a double ellipsoid heat source. The finite element calculations are performed by using ANSYS code with the parametric design capabilities. Experiments were carried out to determine the temperature evolution during welding and to measure the cross section profile of the weld bead. By comparing the simulation results with the corresponding experimental findings, it is found that they are in a good agreement. The validity and applicability of the numerical simulation model are confirmed.
Effect of Scanning Path on Microstructure and Microhardness of Laser Cladding Ti-6Al-4V Alloy
Authors: Wu Dong Jiang , Li Qian , Liang Xiao Kang , Chen Yun Xiao
Published: November 2010

Ti-6Al-4V laser cladding layers were performed on the Ti substrate respectively based on four different laser scanning ways by laser cladding with coaxial powder feeding. The results showed that the morphology of cladding layers in heat overlapping was much smoother than cold overlapping. The possibility of appearance of concave-convex would be increased in the laser cladding performed with reverse scanning direction. However with same direction scanning the possibility of distortion of the substrate would increase. The microstructure of cladding layers in four scanning ways all exhibit epitaxial growth huge columnar β grains in which fine acicular α and Widmanstaten α lath are distributed. The columnar β grains and fine acicular α formed during cold overlapping were denser than during heat overlapping. Also the microhardness of laser cladding zone was improved compared to the substrate no matter in which scanning way while the microhardness in cold overlapping was higher than that in heat overlapping in the same position of cladding zone.
High Speed Twin-Roll Casting of Al-Mg Alloys
Authors: Komeda Kosuke , Nakamura Ryoji , Kumai Shinji
Published: November 2010

The disadvantages of the conventional twin-roll caster for aluminum alloy are low casting speeds and limited choices of alloys that are castable by this processing. It is known that strip casting of aluminum alloy 5182 is very difficult because of their wider freezing zones. The vertical-type high-speed twin-roll caster used in the present study was devised to overcome these disadvantages. Features of the high speed twin roll casters are as below. Mild steel rolls were used in order to increase the casting speed and to be made at a lower equipment cost. Roll coating is produced in casting of Al-Mg alloy. Therefore lubricant, that resists heat transfer, was not used in the present study. Heat transfer between melt and the roll was improved by hydrostatic pressure of the melt. Low superheat casting was carried out in order to improve microstructure of the strip. In the present study, effectiveness of a high-speed twin roll caster for recycling aluminum alloy was investigated. The effects of the high-speed twin roll caster on alleviating the deterioration of mechanical properties by impurities were investigated. Properties of the cast strip were investigated by metalography, a tension test, and a deep drawing test.
Comparative Study and Mathematical Modeling of Machining Parameters in Ultrasonic-Assisted EDM of AISI H13 Tool Steel by the Application of Workpiece Vibration
Authors: Shabgard Mohammad Reza , Sadizadeh Babak , Amini Keivan , Pourziaie Hamid
Published: November 2010

The correct selection of the machining parameters is one of the most significant issues to take into consideration in Ultrasonic-assisted Electrical Discharge Machining (US-EDM) and EDM processes. In the present work, a study has been made to develop and extract statistical models to show the relationship between important machining performance data (material removal rate (MRR), tool wear ratio (TWR) and surface roughness Ra) and the input machining parameters (pulse current, and pulse-on time) in the EDM and US-EDM of AISI H13. The models obtained were used to analyze the effects of input parameters on machining performance. In addition, a comparative study was carried out to investigate the effect of ultrasonic vibration of the workpiece on machining performance. The results show that Ultrasonic vibration of the workpiece can significantly reduce the inactive pulses and improves the stability of process. Also US-EDM is effective in attaining a high material removal rate (MRR) in finishing regime in comparison with conventional EDM. The results of Analysis of Variance (ANOVA) indicate that the proposed mathematical models can adequately explain the performance within the limits of the factors being studied.
Influence of High-Frequency Micro-Forging on the Surface Microstructure and Cracking Behavior of Laser Cladding
Authors: Qiu Chang Jun , Zhou Ju , Fan Xiang Fang , He Bin
Published: November 2010

This paper utilized self-made high-frequency micro-forging machine to treat NiCrBSi alloy cladded by laser, Optical Microscopy(OM) to study geometric characteristic of plastic deformation, OM and SEM to observe influence on surface microstructure and cracking behavior of the laser cladding layer under micro-forging. The results have shown that: Regularly dendrite microstructure, which is peculiar of laser cladding layer, was broken into pieces. Cracking behavior of laser cladding layer improved greatly.
Microstructure and Phase Selection of Undercooled Single-Phase Fe-Co Alloy
Authors: Liu Ning , Yang Gen Cang , Liu Feng
Published: November 2010

Fe-Co single-phase alloy melts with different Co contents were undercooled using fluxing method. The maximum undercooling DT = 457K (relative undercooling DT/Tm=0.259) was achieved in this work. At low undercooling (DT), single-phased microstructure was observed, but metastable bcc phase emerged in the as-solidified microstructure once DT exceeded a critical value, DTcrit. In the presence of classical nucleation theory, phase selection in the undercooled Fe-Co melt was investigated, and the theoretical calculation was coincided with the experimental result.
Study of Machining Microchannels on Quartz by the Laser-Induced Plasma
Authors: Huang Zheng , Feng Cai Ling
Published: November 2010

In order to fabricate high-quality microchannels in a fused silica, the fundamental frequency laser with the wavelength of 1064nm of a Q-switched Nd:YAG laser and the mixing laser composed of 70 percent second harmonic laser and 30 percent fundamental frequency laser are used to irradiate a fused silica substrate respectively to induce the plasma, by which microchannels in a fused silica substrate were fabricated.The result show that the interior wall of the microchannels processed by mixing laser are smoother and the drilling rate is faster than ones processed by fundamental frequency. Furthermore, the depth of the microchannels processed by the mixing laser is up to 8mm, longer than the depth of 4mm reported at present. The reasons of causing to the differences between two kinds of processing are analyzed.
Research on the Effects of Ultrasonic Frequencies on the Grinding Surface Quality of Nano-Composite Ceramics
Authors: Ma Hui , Zhao Bo
Published: November 2010

The effects of multiple ultrasonic frequencies on grinding surface quality of Al2O3-ZrO2 nano-composite ceramics are researched to provide optimization laws for ultrasonic grinding parameters. Some SEM photographs of ultrasonic grinding surface with different frequencies are provided to research the surface quality. The enhanced surface quality of ceramics with ultrasonic grinding is explained as the transition of single abrasive particle removal mode from brittle to ductile, which is resulted from the reduction of equivalent rigidity on surface under ultrasonic vibration. And this phenomenon becomes more evident as frequency increases. Through the XRD experiment, the phase transition from tetragonal phase t-ZrO2 to monoclinic phase m-ZrO2 becomes increasingly obvious by the action of ultrasonic vibration. The compressive stress generated during this phase transition can suppress the initiation and expansion of microcracks on the processing surface. The research shows that, the grinding surface quality with ultrasonic vibration is superior to that without ultrasonic vibration, and increasing ultrasonic frequency can contribute to the improvement of the surface quality.
A New MEMS Assembly Unit for Hybrid Self Micropositioning and Forced Microclamping of Submilimeter Parts
Authors: Hamedi Mohsen , Vismeh Milad , Salimi Parisa
Published: November 2010

In this paper we have presented an assembly unit equipped with electrothermally actuated microclamps (MCs), piezoelectric pad and rotary table to provide an environment for micropositioning and microclamping of submilimeter parts. The structural material of the system is considered to be <100> oriented Si with 20 µm thickness. Activating MCs, two approaches performed in the simulation procedure and results showed that utilizing 140 nm deposited Chromium thin layer on the U-shape structure as active material, reduces the overall input voltage and temperature in comparison with direct applying of potential difference to Si structure. To obtain more realistic results, both of these methods are simulated using finite element software in line with considering temperature-dependent thermophysical properties for structural and active material due to high operating temperatures. Design strategies and other advantages of using thin layer of chromium as active material are highlighted in the text.
Influence of Tool pin Profile on the Microstructure and Mechanical Behavior of Cu/SiC Metal Matrix Composites Produced by Friction Stir Processing
Authors: Barmouz Mohsen , Givi M.K. Besharati , Jafari Jalal
Published: November 2010

Friction stir processing (FSP) is a metal-working technique that causes microstructural modification and change in the upper surface of metal components. In this work the effects of tool pin profile on the microstructure and mechanical behavior of reinforced SiC particles metal matrix composites (MMCs) produced by friction stir processing were studied. Optical microscopy (OM) and Scanning electron microscopy (SEM) was employed to carry out the microstructural observations. Vickers Microhardness Machine used for microhardness evaluation. Results show that, tool pin profile play a major role in improvement of the surface quality, SiC particles dispersion in pure copper matrix, hardness behavior and wear resistance. Two different tool pin profile (straight cylindrical and square) were used to perform the process. It was found that, straight cylindrical tool pin profile led to finer grains, uniform dispersion of SiC particles, higher microhardness and wear resistance values.
Inflluence of Tool Wear on Center Defects of the Workpiece during Cross Wedge Rolling Process
Authors: Liu Gui Hua , Jiang Zhi , Bian Yi , Ren Guang Sheng , Xu Chun Guo
Published: November 2010

Cross wedge rolling (CWR) technology, which is a new metal forming process to produce stepped shaft in forging industry, has developed rapidly in the last decades. Tool wear is a key factor to influence products’ quality during CWR process in practice. Basing on the analysis of characteristic of the tool wear, the similar outline dimension of the worn tool in service is obtained by blocking up the end of the tool. A series of experiments are completed to research the influence of the tool wear on the center defects of the workpiece, and the available method to repair the worn tools is brought forward.
Dynamic Wettability of Rice Straw
Authors: Liu Bing , Wang Feng Hu , Jiao An Ying , Sun Jian Ping , Zhen Meng Ying
Published: November 2010

With JC2000A Contact Angle Measuring Apparatus and established model of rice straw surface wetting, to improve the surface wetting properties of Rice Straw, effects of four kinds of alkali spray on Rice Straw at room temperature on contact angle was studied. The result shows that after alkali treatment the surface wettability of Rice Straw obtained significant improvement, contact angle decreases with the treatment time extended. The contact angle change rate reached the largest within 10min with the decreasing gradient of 20.64% when rice straw was dealt with NaNH2 at the mass fraction of 1%. Under the same conditions, rice straw processing with CaH2 has the minimum gradient contact angle change rate of 3.6%, A large number of Ca(OH)2 formation made The contact angle did not change significantly with time extended. Effect of NaOH treatment changed significantly over time, the optimum conditions of processing technology were obtained through orthogonal test: concentration of NaOH is 0.6%,solvent ratio 1:3.5 and reaction time 12h.
Warm Stamping of Cell-Phone Cases with AZ31 Magnesium-Alloy Sheets
Authors: Chen Fuh Kuo , Chang Chih Kun
Published: November 2010

The stamping process for manufacturing cell phone cases with magnesium alloy AZ31 sheets was studied using both the experimental approach and the finite element analysis. The formability of AZ31 magnesium-alloy sheet at elevated temperatures was studied first. The experimental results reveal that the forming of AZ31 sheets becomes possible as long as the sheet is heated to an elevated temperature and 200oC is an optimum forming temperature to start with. An optimum stamping process, including die geometry, forming temperature, and blank dimension, for manufacturing the cell phone cases was examined by the finite element analysis. The finite element analyses performed for the cell phone were validated by the good agreement between the simulation results and the experimental data. It also confirms that the cell phone cases can be produced with AZ31 magnesium-alloy sheets at elevated temperature by the stamping process. It provides an alternative to the electronics industry in the application of magnesium alloys.
Study on the High-Temperature Coating in Preventing Oxidation and Decarburization
Authors: Lin Sheng Yao , Tang Lu Wen , Zeng Jian Min
Published: November 2010

In order to reduce the oxidation and decarburization caused by high temperature in the course of the heat treatment of metal materials, an environment-friendly coating consisting of glass powder and red mud as the main raw materials is applied. It is brushed on the workpiece surface, heated in the box-type resistance furnace.The high temperature oxidation weight gain and the depth of decarburization between naked steel and coating steel are studied using weight gain method and metallographic method. The impact of the coating to reduce oxidation loss and the main properties of coating are analyzed. The result shows that processing properties of the glass-based coating are excellent:it has no crack at high temperature, distributes uniformly on the workpiece surface and can be self-spalling after quenching. It effectively prevents the workpiece from oxidation and decarburization at 800-1100 . The coating is of low cost and easy to use.
Effect of the Sulfurizing Layer on Tribological Properties of Netted Laser-Quenching Surface
Authors: Zhao Yu Qiang , Che Xin Yuan , Qiao Yu Lin , Zang Yan
Published: November 2010

The sulfurizing layer with a thickness of 8μm was prepared on the netted laser quenching surface of CrMoCu alloy cast iron by means of low temperature ion sulphuration process. The tribological properties of the sulfurizing layer under the condition of dry sliding were investigated by type MFT-R4000 reciprocating friction-wear tester. The morphologies and compositions of the original and worn surface of the duplex coating were analyzed by a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer attachment (EDX). X-ray Diffraction (XRD) was employed to analyze the surface phase structures. The experimental results revealed that sulfurizing layer was loose and porous, and the phase structure of which was mainly FeS. Furthermore, the sulfide on laser treated area was more compact and the grains more exiguous. Under the same experimental conditions, duplex coating possessed a remarkable friction-reducing effect and improved the wear resistance to a certain extent. And that sulfurizing layer could abate the worn-step effect availably.
Corrosion Evaluation for Aluminum Alloy (6262) in Aerated 3.5% NaCl Solutions under Hydrodynamic Conditions
Authors: Musa Ahmed Y. , Kadhum Abdul Amir H. , Mohamad Abu Bakar , Takriff Mohd Sobri
Published: November 2010

The corrosion of aluminum alloy (6262) in artificial sea water under flow condition was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic methods. The flow condition experiments were simulated using rotating cylinder electrode (RCE). Results showed that the increasing of the flow velocity enhances the corrosion kinetic of the system and changes the corrosion mechanism. Limiting current density was increased with increasing in the flow velocity. This behavior was due to the presence of a mixed control on the corrosion process related with the formation and stabilization of corrosion product layers on the electrode surface.
Process and Properties on the Precision Forming of Spline Cold Rolling
Authors: Liu Zhi Qi , Song Jian Li , Li Yong Tang , Li Xu Dong , Wang Ming Fu
Published: November 2010

Cold rolling precision forming process of spline is one of the high-efficiency, precision and non-chip forming advanced manufacturing technologies. It has the characteristics such as high forming efficiency, energy-saving, low material consumption and better forming properties of components. The principle and the force of involute spline cold rolling precision forming process were analyzed. Forming experiments of involute spline cold rolling were carried out, and the microhardness map of the tooth outline was gained. The rule of the metal flow in the deforming area and the forming mechanics of the microstructure were analyzed. The influence of plastic deformation on the forming properties was also conducted. Experimental results showed that dramatic plastic deformation has taken place on the upper surface of the workpiece during the cold rolling process of spline, while the influence on the inner materials were very small. The grains were distributed as a flow line pattern along the tooth profile, and the grains in the plastic deformation zone presented a fine and long fibrous state. The hardness on the section of the tooth outline is regularly distributed. Compared with the spline components obtained from conventional cutting method, the hardness of the spline was greatly increased, therefore, comprehensive mechanical property such as wear resistance and impact resistance were largely improved. Precision measuring and hardness testing of the tooth outline section showed that the components obtained by the experiments were free of defects, and the application requirement can be satisfied.
Theoretical Analysis of Serrated Chip Formation Based on Ideal Models in High Speed Cutting
Authors: Gao Chong Yang , Fang Bin , Gu Yuan Tong
Published: November 2010

In this paper, two ideal formation models of serrated chips, the symmetric formation model and the unilateral right-angle formation model, have been established for the first time. Based on the ideal models and related adiabatic shear theory of serrated chip formation, the theoretical relationship among average tooth pitch, average tooth height and chip thickness are obtained. Further, the theoretical relation of the passivation coefficient of chip’s sawtooth and the chip thickness compression ratio is deduced as well. The comparison between these theoretical prediction curves and experimental data shows good agreement, which well validates the robustness of the ideal chip formation models and the correctness of the theoretical deducing analysis. The proposed ideal models may have provided a simple but effective theoretical basis for succeeding research on serrated chip morphology. Finally, the influences of most principal cutting factors on serrated chip formation are discussed on the basis of a series of finite element simulation results for practical advices of controlling serrated chips in engineering application.