bluuebunny/crossref_metadata_2025 huggingface dataset:
High-Efficient Damage-Free Correction of the Thickness Distribution of Quartz Crystal Wafer Using Open-Air Type Plasma CVM
Authors: Yamamura Kazuya , Morikawa Tetsuya , Ueda Masaki
Published: August 2015

Thickness uniformity of an AT-cut quartz crystal wafer is essential requirement for higher productivity of quartz resonator in the sense of reducing the frequency adjusting process after dicing the wafer. However, commercially available quartz crystal wafers typically have a thickness distribution of ±0.1%, which is induced in conventional mechanical fabrication processes, such as cutting with a wire saw, lapping and polishing. Furthermore, owing to the poor parallelism and the existence of subsurface damage, many spurious peaks, which deteriorate resonance characteristics, are observed in a resonant curve. To resolve these issues, we proposed a new damage-free finishing method to correct the thickness distribution of an AT-cut quartz crystal wafer by the numerically controlled scanning of a localized atmospheric pressure plasma. By applying a new finishing process, the thickness uniformity of a commercially available AT-cut quartz crystal wafer was improved to less than 50 nm level by applying one correcting process without any subsurface damage. Furthermore, applying of the pulse-modulated-plasma drastically decreased the correcting time of the thickness distribution without breaking of the quartz crystal wafer by the thermal stress.
Ultra-Precision Machining of Dies for Microlens Arrays Using a Diamond Cutting Tool
Authors: Yoshikawa Takehisa , Kyoi Masayuki , Maeda Yukio , Ohta Tomohisa , Taya Masato
Published: August 2015

Patterning of numerous microlenses on a surface improves the optical performance of components such as liquid crystal displays. A cutting method using a diamond tool is examined to fabricate a molding die that employs arbitrary array patterns to mold millions of microlenses. The present paper investigates machining of microlenses on the order of 2 kHz, using a piezo-actuated micro cutting unit and a synchronous control system of the cutting unit with an NC controller. Experiments using this system revealed that it is possible to machine a large number of microlenses on a molding die with high precision.
Effect of Potential Function on Molecular Dynamics Simulation of Copper Processing
Authors: Wang Jia Chun , Zhang Ji Min , Li Na , Kou Yun Peng
Published: August 2015

In nanometric cutting process, the actual material removal can take place at atomic level, which makes it difficult or impossible to observe the machining phenomena and measure the cutting parameters in experiments. However, it is crucial to investigate the cutting process in nanoscale. In this study, the molecular dynamics (MD) method is employed to model and simulate the process of cutting monocrystalline copper. The two-body Morse potential and the many-body EAM potential are used for the atoms interaction in the workpiece to study the effect of different potential function on the simulation results. It is found that there are no obvious differences in the chip formation between Morse and EAM potential, but the Morse potential results in higher potential energy and more chips generated in the cutting process.
Ultra Precision Diamond Shaping of an Elliptical Micro-Lens Array
Authors: Chao Choung Lii , Chen Chun Chieh , Chou Wen Chen
Published: August 2015

Micro lens array is widely used in photonics and telecommunication products, including back-light module of flat panel display devices and white-light LED illumination. The ultra precision diamond shaping method together with tool servo technique was studied and developed in this research to generate elliptical micro lens array. Each elliptical micro lens has radii in X and Y direction of 1.0 mm and 1.5 mm respectively. A high filling-factor (100 %) elliptical micro lens array with form accuracy better than 0.15μm and surface roughness around 5nm Ra was successfully fabricated.
Off-Line Feedrate Optimization Based on Simulation of Cutting Forces
Authors: Zhang Chen
Published: August 2015

The strategies of selection of feedrate are studied in the ball-end machining process. The optimization algorithm utilizes the objective requirements of a line of NC program to set constraints relation between cutting force and feedrate and optimizes feedrate by controlling the variety ranges of the instantaneous cutting force specified in the cutting forces simulation. Off-line feedrate optimization software for complex sculptured is developed. For a line of NC program, the developed software calculates instantaneous cutting force and an optimization algorithm is used to acquire desired feedrate. The machining experimental results show that the proposed algorithms are satisfying in reduction of machining time and improvement of machining quality.
Thermal-Mechanical Effect on Temperature/Stress Distribution when Orthogonal Cutting Bearing Steel
Authors: Wang He Ping , Zhang Xue Ping
Published: August 2015

An explicit dynamic coupled thermal-mechanical Arbitrary Lagrangian Eulerian (ALE) model was established to simulate orthogonal cutting AISI 52100 bearing steel, and its temperature and stress distribution. Based on ABAQUS, The ALE approach effectively simulates plastic flow around round edge of the cutting tool without employing chip separation criteria. The calculation results reveal that cutting speed and cutting depth have great impact on chip morphology, stress and temperature distribution in the finished surface and subsurface, the predicted temperature agrees well with experiment data obtained under the similar cutting conditions as well as the change in chip morphology from continuous to sawtooth as the cutting speed increases.
Modelling the Polishing Efficiency of Polycrystalline Diamond Composites by the Dynamic Friction Method
Authors: Chen Yi Qing , Nguyen Thai , Zhang Liang Chi
Published: August 2015

This investigation aims to develop a quantitative model to estimate the material removal of polycrystalline diamond composites by dynamic friction polishing. The model accounts for not only the polishing parameters that govern the material removal mechanisms, but also the constitutive properties of the diamond composites subjected to polishing. The model prediction was justified by relevant experimental measurements.
Study on the Effect of Tool Inclination Angle in Machining Process Based on Three-Dimensional Thermo-Elastic-Plastic Model
Authors: Dong Hui Yue , Xue Hui , Huang Pu Jin
Published: August 2015

Based on large deformation theory and virtual work principle, a coupled three-dimensional (3D) thermo-elastic-plastic finite element model (FEM) was constructed to simulate the high speed cutting process of Al7050-T7451. The mechanical properties of workpiece material under conditions of high temperature and high strain rate were defined in the model. A shear friction model was involved at the interfaces of tool-chip, tool-workpiece. Based on the model, different 3D machining FEM with different inclination angles were established, and distributions of stress, strain and temperature were achieved. Further more, the effects of inclination angle on the chip curling direction, chip flow angle, cutting force and cutting temperature were studied.
Study on Micro Drilling — Rotating Bending Fatigue of Micro Carbide Drills
Authors: Ma Bo Xiao , Nomura Mitsuyoshi , Kawashima Takahiro , Shibata Takayuki , Murakami Yoshihiko , Masuda Masami , Horiuchi Osamu
Published: August 2015

In micro drilling, the run-out of drill due to rotational motion error of spindle or eccentric chucking of drill causes machining error and larger radial forces which may break the drill. Furthermore, because the spindle speed is very high, rotating bending fatigue of drill may dominate the tool life. In the previous work, relationship between bending deflection and radial cutting force, and fatigue fracture of drill were investigated theoretically and experimentally. The objective of this paper is to investigate more in detail the relationship between the radial cutting force/deflection of drill and its fatigue life. A series of pseudo rotating bending fatigue tests was performed by using three types of ultrafine grain carbide drill blank with 0.1mm diameter. The main results obtained are as follows, (1) Rotating bending fatigue curve did not depend on cobalt content and tungsten carbide grain size. This differs from the results of conventional cemented carbides. (2) The fatigue fracture surface was dominantly occupied by fast fracture regions.
Study on Machining Error in Ball End Milling of Spherical Surface
Authors: Tanaka Hisataka , Sato Masahiko , Yoshida Hiroshi , Ohta Satoki , Okamura Susumu
Published: August 2015

This paper presents the results of a series of experiments performed to examine the validity of a theoretical analysis for evaluation of machining error in ball end milling of spherical surface. In the analysis, the trochoidal paths of cutting edges are considered in the evaluation of chip geometry. The cutting forces are evaluated based on the theory of oblique cutting. The machining errors resulting from cutting force induced tool deflections are calculated at various parts of the machined surface. The experiments are carried out at various cutting conditions for convex spherical surface, and the influences of cutting mode and milling position angle on machining error are examined.
Material Removal Model of Sapphire Substrate in Double-Side Lapping Process
Authors: Lu Cong Da , Qian Dong Min , Jiang Shao Fei
Published: August 2015

The material removal mechanisms of sapphire substrate in double-side lapping process were studied. The concepts of brittle vs. ductile machining and two-body vs. three-body abrasion were used to classify the processing mechanisms. The material removal models of double-side lapping process in different mechanisms were analyzed and researched. The experiment showed that the material removal model can describe double-side lapping process of sapphire qualitatively.
The Relationship between Dynamic Components of Cutting Force and Adhesion of Tool-Chip Interface
Authors: Tezuka Ryo , Sekiya Katsuhiko , Yamada Keiji , Yamane Yasuo
Published: August 2015

A new method for evaluation of adhesion in cutting is proposed. Adhesion of chip induces fluctuation in chip flow or stick-slip movement of chip, so that dynamic component of cutting forces depends on the cutting conditions and properties of the work materials. In this investigation continuous turning of a medium carbon steel was carried out and dynamic components of cutting forces are measured by piezoelectric dynamometer. Fluctuation in dynamic force on rake face of the tool is considered at a range of cutting speeds under dry condition and oil-mist lubrication. Surface profiles of machined surfaces and sticking of chip on tool face were also investigated. In cutting of medium carbon steel, the dynamic components below 500Hz increased under the condition of build-up edge (BUE) formation, and gradually decreased as increase of cutting speed. Tool-edge geometry well transferred onto the machined surface when the dynamic components were low level. Smoothness of chip flow on rake face is strongly associated with good surface finish.
Application of a Drill Resistance Technique for Rapid Determining Wood Density
Authors: Zhang Hou Jiang , Guo Zhi Ren , Su Juan
Published: August 2015

A study measured the drill resistances of larch and Scotch pine by a drill resistance technique and compared the densities of the same specimens measured with a traditional volumetric method. The drill resistance technique was found to be a good measure of the density profile of wood to reflect tree rings and defects (knots, decay and hollows). The drill resistance technique as applied to pines uses a linear relationship between the wood density and the average drill resistance. This technique has the applicability and possibility as a possible method for the density measurement and the defects detection. The technique is rapid, inexpensive, safe, portable and has the potential to be adopted as an on-line density profile method.
A Feedrate Scheduling Strategy Based on a General Force Model
Authors: Cai Yu Jun , Duan Chun Zheng , Sun Li Jie
Published: August 2015

Sculpture surface machining is a critical process commonly used in die/mold industries. Since there is a lack of scientiﬁc tools in practical process planning stages, feedrates for CNC machining are set individual constant values all along the toolpath. In this paper, an enhanced mathematical cutting force model is presented and is used for selecting varying and ‘appropriate’ feed values along the tool path in order to decrease the cycle time in sculpture surface machining. The model is tested under various machining conditions and proved to be effective.
Machining of Difficult-to-Cut Materials with a Lubricant Coated Tool
Authors: Isaka Masakazu , Hiroshi Usuki , Sakamoto Satoshi , Kubota Kazuyuki
Published: August 2015

Tools coated with TiBON films of varying boron concentrations were made, and the influence of boron concentration on tool wear was investigated. The TiBON coating film acts as a lubricant at high temperature. Tools coated with such films were applied to the machining of difficult-to-cut materials (Ti-6Al-4V and Inconel 718), where　the cutting temperature increases rapidly and heavy adhesion occurs. In the experiment, turning and interrupted cutting were performed. In cutting of Ti-6Al-4V, the tool coated with a film of high boron concentration showed long tool life. In turning of Inconel 718, the tool coated with a film of a boron concentration of 15% showed the longest tool life-about four times longer than that of a tool coated with TiAlN.
Determination of the Flow Stress of Ti6Al4V Based on Cutting Experiment and Optimization
Authors: Yuan Yue Feng , Chen Wu Yi , Liu Dong
Published: August 2015

A methodology to determine the flow stress of material was presented and Johnson–Cook (JC) constitutive model of titanium alloy Ti6Al4V was obtained based on cutting experiment and optimization. This JC model was verified by comparison between simulations with different JC models respectively and experiment. It showed that the accuracy of simulation of cutting force has an increase and the new model is more suitable for cutting simulations. This simple method could improve the accuracy and reliability of the cutting simulation, and could be used to establish the constitutive model of workpiece with more accuracy.
Dynamic Simulation and Cutting Conditions Optimization of Tee Slot Milling Based on CutPro Software
Authors: Li Zhong Qun
Published: August 2015

. Based on the dynamic simulation module of CutPro, the dynamic cutting forces and chatter limits for tee slot milling were predicated by setting the geometry of a tee slotting cutter. The chatter stability lobes under a given axial depth of cut are obtained by further programming, which is essential for chatter-free tee slot milling. A methodology of cutting conditions optimization for tee slot milling is presented, in which the minimal cutting time is used as the target function and the stability limits are introduced into the constraint conditions to reflect the vibration characteristics of milling operation. This optimization method has been validated by experimental tests.
Effect of Co Content and WC Grain Size on Wear Resistance of Micro Carbide Endmills in High Speed Milling of Graphite
Authors: Zhou Li , Wang Cheng Yong , Li Yu Zhong , Qin Zhe
Published: August 2015

Micro carbide endmills suffer severe abrasive friction and impact wear in high speed milling of graphite. This paper focused on the study of the effect of Co content and WC grain size on the tool wear resistance of micro carbide endmills in high speed milling of graphite. The tool wear morphologies of cutting tools were examined at the initial wear stage and severe wear stage. The results showed that the abrasive resistance of micro carbide endmill increased with the decrease of Co content and WC grain size. The best impact resistance can be obtained with medium Co content and smaller WC grain size. The fine-grained carbide 0.2WC-8%Co is considered as the optimum tool material for high speed milling of graphite.
Effect of Ultrasonic Vibration of Tool on Electrical Discharge Machining of Sintered NdFeB Magnet
Authors: Li Li , Niu Zong Wei , Yuan Guang Ming
Published: August 2015

Sintered NdFeB magnet is widely used in many areas because of its excellent magnet. This paper studies the effect of ultrasonic vibration of tool on electrical discharge machining of it. Experiments were carried out on self-made equipment and material removal rate(MRR) against pulse-on time, MRR versus peak current and machined surface results with and without ultrasonic employment were analyzed. Results show that MRR of the ultrasonic assisted electro-discharge machining would be up to five times higher than MRR of the conventional EDM for small pulse durations and low discharge currents. The machined surface of US/EDM is finer than EDM because of less arcing and short circuit pulses. There are less cracks on the surface.
Analysis on the Instantaneous Stiffness of the 3-RPS Parallel Machine
Authors: Han Xian Guo , Cui Xue Liang , Chen Wu Yi
Published: August 2015

Based on the screw theory, the force analysis of the 3-RPS parallel machine is illuminated. Been equivalent to a 6-chain parallel machine, the deformation harmony equation of the parallel machine under the outside generalized force is interpreted. The instantaneous stiffness model of the parallel machine, which includes the change of the force Jacobian matrix, is established. Considering the deviation of the position and orientation of the moving platform, which is resulted from the distortion of the PRS chains of the parallel machine, the influence of the change of the Jacobian matrix to the instantaneous stiffness model of the 3-RPS parallel machine is analyzed, and furthermore, it is verified with an instance.
The “Effective Region” Characteristic of the Tool Life in Vibration Drilling
Authors: Zhang Peng , Guo Xing Yu , Zhang De Yuan
Published: August 2015

There are different opinions on whether the tool life could be improved by the vibration drilling or not. The factors which affect the drill life during micro hole drilling were analysed, and the vibration drilling has the effective region characteristic for drill life. That is to say, the vibration drilling can extend the tool life significantly within the certain range of the hole depth (or depth-diameter ratio). The stainless micro hole drilling experiments were done, and the results showed that the life advantage for vibration drilling was represented on certain region, that is effective region phenomenon
Effect of Thickening Agent on Water-Based Working Fluid for EDM
Authors: Ji Ren Jie , Liu Yong Hong , Yu Li Li , Chen Ji Ming , Shen Rong , Li Xiao Peng
Published: August 2015

Different thickening agents are added into the prepared water-based working fluid for electrical discharge machining (EDM), and the influence on the process performance is investigated in this paper. The experimental results demonstrate that the proper addition of polyvinyl alcohol (PVA) and coconut diethanol amide (CDEA) can increase the material removal rate of EDM, advance the electrical conductivity of the working fluid and enlarge the discharge gap, but has a little influence on the relative electrode wear ratio. Moreover, the material removal rate can increase 1.1 times and 1.3 times with proper addition of PVA and CDEA respectively in comparison with no thickening agent, and the addition of CDEA promotes better EDM performance
Study on Cavitation Aided Abrasive Machining on Glass
Authors: Ohashi Kazuhito , Tsukamoto Shinya , Nakajima Toshikatsu
Published: August 2015

The purpose of this study is to develop the cavitation aided abrasive machining which makes effective use of cavitation occurring in suction flow of slurry for fine machining. In this paper, a fundamental machining phenomenon of glass using the cavitation suction flow is clarified and machining characteristics are experimentally investigated by the observation of machined surface and surface roughness, stock removal and cavitation impact. Abrasive grains impinge on a workpiece surface to physically remove work material and generate fine surface in the machining. Then it can finish the polished glass surface of 9.3nmRz down to about 5.0nmRz by using abrasives of WA 4000.
A Denoise Method of Electrical Discharge Machining Gaps Signal for Non-Conductive Engineering Ceramics Based on Wavelet MMA
Authors: Shen Rong , Liu Yong Hong , Chen Ji Ming , Zhang Hai Feng , Ji Ren Jie
Published: August 2015

EDM; Gap voltage/current; Wavelet analysis; Modulus maxima algorithm
Abstract: According to the characteristics of Electrical Discharge Machining Gaps Signal for Non-conductive Engineering Ceramics, the wavelet modulus maxima algroithm was uesed to denoise the gaps voltage/current signal. Compaered the differernt denoising result of different wavelet function, Maxihat wavelet, Meyer wavelet, Daubechies wavelet and Gaussian wavelet, the fitting wavelet function, Gaussian wavelet which used to denoising the EDM Gaps voltage/current signal was found out, and the fitting scales space [-5,+1] and the normalized threshold value interval [0.1,0.3] was determined.
Design of a Simultaneous Module Using Burnishing and Electrofinishing on Hole-Wall Surface
Authors: Pa Pai Shan
Published: August 2015

This study discusses a method for increasing the efficiency and speed with which an improvement in surface roughness of a hole-wall surface can be achieved. The surface after traditional machining is discussed as well as a method for finishing the hole-wall surface using a design of finish-tool that includes a nonconductive knothole-form burnishing-tool and a ring electrode to execute simultaneous burnishing and electrofinishing (SBEF). By the dual and synchronous effect of the electrode and the burnishing-tool a superior hole-wall finish is achieved. In the experiment, the use of a small arc rounding radius and a thin finish-tool is advantageous to the finishing effect. A high rotational speed of the finish-tool produces a better finish. A high current and a faster finishing tool feed is also effective in gaining a rapid improvement of the roughness of the hole-wall surface and is recommended from the results of the current study.
Numerical Analysis of Surface Residual Stress of NC Milling 7075-T7451 Aluminum Alloy
Authors: Wang Hong Feng , Zuo Dun Wen , Wang Li Tao , Miao Hong , Wang Hong Jun
Published: August 2015

The mathematic model was established between finished surface residual stress and milling parameters by orthogonal regression testing. The rationality of the model was certified by FEM and test. The simulation hypothesis and process were verified by the model. The test showed that the model and FEM were feasible.
Experimental Research on Wear Resistance of Deep Cryogenic Treated HSS Twist Drill
Authors: Xu Hong Hai , Wang Hong Yan , Li Xin Min
Published: August 2015

On the base of deep cryogenic treatment(DCT) and drilling experiments of W9Mo3Cr4V, W6Mo5Cr4V2 and W4Mo3Cr4VSi HSS twist drills, the influence of deep cryogenic treatment on hardness, wear resistance and microstructure was studied. The experimental results indicated that deep cryogenic treatment induced transformation of retained austenite to martensite and formation of fine carbide particles, so the toughness, wear resistance and hardness values of HSS twist drill were improved. Life of DCT drills was 2 to 4 times more than untreated drills.
Novel Positioning Devices for Ultraprecision Machine Tool
Authors: Mizumoto Hiroshi , Yabuya Makoto
Published: August 2015

For ultraprecision machine tool of the next generation, two novel positioning devices are invented by the authors. The first positioning device of nanometer and sub-nanometer resolution with long stroke is the Twist-roller Friction Drive (TFD). For long stroke with 1nm of positioning resolution, the TFD is driven by a servomotor, and it is driven by a piezoelectric actuator for short stroke with 0.1nm of positioning resolution. The second positioning device of short stroke picometer resolution is an active aerostatic guideway employing the Active Inherent Restrictor (AIR). The stroke of the active aerostatic guideway is in the order of 0.1μm, however, the positioning resolution can be 50pm. These positioning devices are integrated into a tri-mode positioning system and each positioning mode is controlled by a numerical control system.
Study on the Accuracy of 3-RPS Parallel Machine Tools
Authors: Xiong Jun , Han Xian Guo , Chen Wu Yi
Published: August 2015

According to the inverse solutions of 3-RPS parallel machine tools, the mapping relationship between the geometrical errors built on the 3-RPS parallel machine tools and errors of out posture has been created, then the error model of direct solutions including all the geometrical parameter errors has been built, and this model can be directly used to analyse the accuracy of parallel mechanism. On this basis, the algorithm about error compensation has been proposed. Moreover, accuracy synthesis of 3-RPS parallel machine tools was made respectively in probabilistic synthesis method and extreme synthesis method, and at last these two methods were compared.
Determination of Mechanical Adhesion Energy of Thermal Oxide Scales on Steel Produced from Medium and Thin Slabs Using Tensile Test
Authors: Nilsonthi Thanasak
Published: August 2015

The mechanical adhesion of thermal oxide scales formed on industrial hot-rolled steel strips produced through the electric-arc-furnace route was studied. The samples as-received steel were prepared with the specific shape fitting to the micro-tensile machine in the SEM chamber for observation of surface failure during the test. It was found that oxide transverse cracking and scale spallation are observed. This paper also presented a theoretical model for evaluate adhesion energy from strain and stress values at the first spallation. It was found that the oxide scales on the medium slab exhibited high mechanical adhesion energy. This might be due to the existence of oxide contained Si at steel-scale interfaces. It can promote adhesive interactions between steel-scale interfaces.
The Role of Fluorosurfactant on Cu-Sn Electrodeposition from Methanesulfonic Acid
Authors: Pewnim Naray , Roy Sudipta
Published: August 2015

Methanesulfonic acid (MSA) is an environmentally benign supporting electrolyte that is an attractive alternative to traditional copper and tin plating baths based on cyanide or fluoborate. This is mainly due to its low toxicity, volatility, and good biodegradability as well as other desirable characteristics for electrodeposition such as high metal salt solubility and conductivity. The role of fluorosurfactant on Cu-Sn electrodeposition from methanesulfonic acid was explored through the use of an electrochemical quartz crystal nanobalance to monitor surfactant adsorption and desorption from the electrode surface. It was found that the surfactant adsorbs on the surface and inhibits copper deposition by blocking the reduction and oxidation reaction for copper.
Microstructure and Mechanical Properties of Welding Repair of 5083 Aluminum Alloy
Authors: Sukawet Supachai , Muangjunburee Prapas
Published: August 2015

The repair welding of aluminum alloy 5083 was studied using Gas Metal Arc welding (GMAW) process. The effect of heat cycles from welding was investigated in some details. Butt joints of 6 mm and 3 mm thick were welded with 5356 filler metal. Then weld was removed by grinding and repeatedly welded again for 2 times. After each repair weld, the weld was assessed by macrostructure, microstructure and mechanical tests. The results revealed porosities of all weld samples. The repair welds indicated lower tensile strength compared with the new welds. In addition, all tensile strengths were much lower than the base metal. All samples were fractured at the weld metal.
The Decomposition of Zinc Ferrite in Electric Arc Furnace Dust by Carbon
Authors: Polsilapa Sureerat , Intakuean Panupong , Promboobpa Aimamon
Published: August 2015

The objective of this research is to study the mechanism of the decomposition of zinc ferrite to obtain crude zinc oxide (ZnO) and iron oxide by using carbon (activated carbon) powder as the reducing agent. Zinc ferrite could be mostly found in electric arc furnace dust (EAFD). Carbon with a purity of 99.99 percent by weight was ground to be fine powder with an average size of 75 microns. Then the mixer between zinc ferrite with carbon powder and EAFD with carbon at the ratio of 1:1, 1:2 and 1:3 by mole was carried out. The samples were treated in the range of temperatures at 600, 700 and 800 °C in TGA. The treated samples were analyzed by XRD in order to identify the phase transformation of zinc ferrite. It was found that the quantity of zinc ferrite, both either pure zinc ferrite and the zinc ferrite in EAFD were decreased after treating by carbon when using treating time at 120 minutes with the temperatures of 600, 700 and 800 °C, and ratio of zinc ferrite with carbon powder at 1:3 by mole. Moreover about 70% of zinc ferrite was decomposed to be zinc oxide (ZnO) and iron oxides.
Wear Behavior of Hardfacing Deposits on 3.5 % Chromium Cast Steel
Authors: Srikarun Buntoeng , Muangjunburee Prapas
Published: August 2015

The objective of this research is to develop the welding procedure for multilayer hardfacing of 3.5 %chromium cast steel and study wear behavior of hardfacing deposits. Austenitic stainless steel and martensitic hardfacing electrodes were selected as buffer and hardfacing, respectively. Four types of welding procedures were investigated, using shielded metal arc welding (SMAW) process. Three different preheatings were applied in this study. Characteristic of the macro, microstructure and worn surface deposits was investigated by optical microscope. The hardfacing deposits were also determined by the dry sand rubber wheel machine according to procedure A of the ASTM G65 standard. The results indicated that the multilayer hardfacing with and without preheating revealed no crack or defect in the Heat Affected Zone (HAZ) and other regions. The wear resistance of hardfacing presented a little difference. The best abrasive wear resistance was obtained from sample without preheating. This was due to the full martensitic microstructure of the hardfacing.
Wear Behavior of Hardfacing Deposits on Hadfield Steel
Authors: Dumrudkarn Chanin , Muangjunburee Prapas
Published: August 2015

The objective of this research was to develop the welding procedure for multilayer hardfacing of 13% Mn cast steel and study behavior of hardfacing deposits after impact applied. Austenitic stainless steel and martensitic hardfacing electrode were selected as buffer and hardfacing, respectively. Two different atmospheric conditions were compared which the first was controlling cooling rate on specimen by water during welding and another was un-controlling (by air), using shielded metal arc welding (SMAW) process. Macrostructure and microstructure were investigated by optical microscope. The hardfacing deposits were also determined by the dry sand rubber wheel machine according to procedure A of the ASTM G65 standard. The results indicated that the hardfacing layers revealed martensitic type microstructure in both controlled and uncontrolled cooling rate but their grain shapes were a little difference. For buffer layer showed austenitic type microstructure. And base metal layer presented amount of carbide in controlled cooling rate is less than in another one. The best wear resistance was obtained from controlled cooling rate condition.
Effects of Ageing Periods on Compositions and Sizes of Titanium Dioxide Particles Synthesized by Sol-Gel Technique
Authors: Jongprateep Oratai , Puranasamriddhi Rachata
Published: August 2015

Titanium dioxide has attracted worldwide attention due to its prominent photocatalytic activity. It is generally accepted that nanoparticulate titanium dioxide with pure anatase structure exhibits high reactivity. Sol-gel is a simple and cost-effective technique capable of synthesizing anatase-phase titanium dioxide with particle sizes in nanometer range. This research aimed at examining effects of ageing periods on compositions and sizes of titanium dioxide synthesized by sol-gel technique. Experimental results revealed that prolonged ageing period demoted formation of anatase phase. Pure anatase phase was observed at ageing period of 1 day, while both anatase and rutile phases were observed at ageing periods of 4 and 7 days. The results also indicated that particle sizes decreased as the ageing periods increased. Nanoparticulate titanium dioxides with average sizes of 71.5, 50.4, and 29.7 nanometer were observed at ageing periods of 1, 4, and 7 days, respectively.
Effect of Thermal Exposure on Long-Term Heated Microstructures at 900°C of Nickel Base Superalloy Turbine Blade, Grade Inconel 738
Authors: Wangyao Panyawat , Polsilapa Sureerat , Singmaneesakulchai Surang , Promboopha Aimamorn
Published: August 2015

The objectives of this research are to search for the most appropriate heat treatment condition for rejuvenating microstructure of cast nickel base superalloy, grade IN-738, turbine blades after using to prolong its life time service again. The turbine blades that had been used for long term service under load and high temperatures resulted in small gamma prime particles connecting to each other and thus forming into larger particles. This effect generally reduces creep resistance and increases the failure. In this research, 5 IN-738 superalloy samples were reheat-treated under simulation of 2 working conditions. First, they were heated at 900oC. At every 400 hours from the beginning of heat treatment until time reaching 1600 hours, these samples were collected and examined the microstructures, size and area fraction of gamma prime particles. Another heating program, they received an over thermal exposure heating at 1125oC for 1 hour after long-term heated at 900oC after every 400 hours-heating. Then the results were analyzed from working conditions. It was found that the sample passed solutioning at 1125oC for 4 hours and aging at 845oC for 24 hours with the over thermal exposure showed the most stable phase stability with γ’ phase increasing after long-term simulated working conditions .
Determination of Stress-Strain Curve of Dual Phase Steel by Nanoindentation Technique
Authors: Punyamueang Suttirat , Uthaisangsuk Vitoon
Published: August 2015

The advanced high strength (AHS) steels, for example, dual phase (DP) steels, transformation induced plasticity (TRIP) steels and complex (CP) steels principally exhibit multiphase microstructure features. Thus, mechanical behavior of the constituent phases significantly affects the resulting overall properties of such AHS steels. Novel material characterization techniques on micro- and nano-scale have become greatly more important. In this work, stress-strain response of the DP steel grade 1000 was determined by using the Nanoindentation testing. The DP steel showed the microstructure containing finely distributed martensite islands of about 50% phase fraction in the ferritic matrix. The nano-hardness measurements were firstly performed on each individual phase of the examined steel. In parallel, finite element (FE) simulations of the corresponding nano-indentation tests were carried out. Flow curves of the single ferritic and martensitic phases were defined according to a dislocation based theory. Afterwards, the load and penetration depth curves resulted from the experiments and simulations were compared. By this manner, the proper stress-strain responses of both phases were identified and verified. Finally, the effective stress-strain curve of the investigated DP steel could be determined by using 2D representative volume element (RVE) model.
Effects of Isothermal Aging on Microstructure Evolution of Biomedical Co-Cr-Mo Alloy
Authors: Khaimanee Pitak , Choungthong Paiboon , Uthaisangsuk Vitoon
Published: August 2015

Cobalt based alloys have been widely used in orthopedic implants. These alloys are an allotropic metal, which commonly exhibits two crystal structures, namely, FCC and HCP lattice. In this work, developed microstructure and hardness of a Co-Cr-Mo alloy after isothermal aging treatment were investigated. The applied aging procedure included soaking at the temperature of 850°C for five different holding times of 1, 3, 6, 9 and 12 h with subsequent water quenching. Microstructure examination, X-ray diffraction analysis and micro-hardness test were carried out for both as-received and heat-treated cobalt based alloys. The results showed that the FCC to HCP phase transformation occurred during the isothermal aging. It was observed that phase fraction of the identified HCP phase increased with longer aging time. Microstructure of the samples aged for 12 h showed very fine lamellae morphologies similar to a pearlitic structure with different orientations within each FCC grain. Apparently, these occurred lamellae structures could be well correlated with the formation of the HCP martensite. Additionally, it was found that in the Co-Cr-Mo alloy sigma phase precipitated early at the grain boundaries and further grew along these boundaries by increasing aging time. The hardness value of the examined alloy slightly increased with larger HCP phase fraction. The increased aging time certainly led to higher amount of the HCP martensite and consequently increased hardness and possible wear resistance properties.
Effect of Copper and Zinc on Microstructures, Melting Points and Corrosion Resistance of Sn-Zn-Cu-Bi Soldering Alloys
Authors: Terdthaichairat Weerawat , Senthongkaew Payoon , Techapiesancharoenkij Ratchatee
Published: August 2015

Sn-Zn alloy is one of the Pb-free systems that are promising because of its relatively low melting temperature and low cost. However, Zn exhibits poor corrosion and oxidation resistance that hinders its soldering applications. The objective of this research is to study the effect of Zn and Cu alloying contents on the Sn-Zn performance. Four compositions of Sn-Zn alloys were studied in this research including: Sn-7Zn, Sn-9Zn, Sn-9Zn-2Cu-Bi, and Sn-9Zn-4Cu-Bi. The microstructures were studied using Optical Microscope (OM) and Scanning Electron Microscope (SEM). The melting temperatures and corrosion resistance of the alloys were evaluated by Differential Scanning Calorimeter (DSC) and Potentiodynamic Polarization technique, respectively. The results showed that an increase in the Cu-to-Zn ratio led to better corrosion resistance. The selective corrosion of the Zn-rich phase could be visibly observed, with OM, on the post-corrosion samples. With the Cu alloying, the Cu and Zn formed an intermetallic compound resulting in a higher value of Ecorr. However, the higher Cu content caused a significant increase in the liquidus temperature due to the Cu-Zn intermetallic compound, of which the melting temperature is higher than 400 °C, resulting in an incomplete melting at low temperature.
Effects of Cooling Rate and Carbon Content on Mechanical Property of Sintered Fe-Cr-Mo Alloys
Authors: Kiatdherarat Wasita , Mungsantisuk Pinai , Tongsri Ruangdaj , Mahathanabodee Sithipong , Sirivedin Kumpanat , Krataitong Rungtip , Morakotjinda Monnapas , Yotkaew Thanyaporn , Tosangthum Nattaya
Published: August 2015

Advanced high strength steel (AHSS) was prepared using the conventional ‘press and sinter’ process.The compacts of ultralow carbon Fe-Cr-Mo powder with carbon additions (base metal powder admixed with 0.1,0.2 and 0.3 wt.% graphite) and without carbon addition (plain base powder) were sintered in a vacuum furnace at pressure of 1.28 x 10-5MPa at 1280 °C for 45 min. After sintering, the sintered specimens were continuously cooled with different nitrogen gas pressures of 0, 2500 and 5000 mbars (or 0, 0.25, 0.5 MPa). Mechanical properties of the sintered alloys were strongly controlled by carbon contents and cooling rates after sintering. The sintered specimens, with 0.3 wt.% carbon and cooled by nitrogen of 5000 mbars, showing superior tensile strengths and good ductility, had microstructures dominated by carbide-free bainitic structures and some retained austenite. The sintered specimens with lower carbon contents and cooled under slower cooling rates, having lower tensile strengths but slightly higher ductility, had microstructures with lower bainite volume fractions and even without bainitic structures. The dominant phase in the sintered specimens with low strength but high ductility was ferrite.
Effects of Destabilisation Heat Treatment on Microstructure, Hardness and Corrosion Behaviour of 18wt.%Cr and 25wt.%Cr Cast Irons
Authors: Wiengmoon Amporn , Chairuangsri Torranin , Pearce John T.H.
Published: August 2015

Effects of destabilisation heat treatment on microstructure, hardness and corrosion resistance of 18wt.%Cr and 25wt.%Cr irons have been investigated. The as-cast samples were heat-treated by destabilisation at 1000°C for 4 hour and then air cooling. The microstructure was investigated by light microscopy and scanning electron microscopy. The results show that the as-cast microstructure in 18wt.%Cr iron consists of pearlite, formed by decomposition of primary dendritic austenite, plus eutectic structure. In the 25wt.%Cr iron with lower hardness, the microstructure consists of primary dendritic austenite plus eutectic structure. The austenite had partly transformed to martensite, especially at areas adjacent to eutectic carbides. After destabilisation, the microstructure of both irons consists of eutectic and secondary carbides in a martensite matrix giving increased hardness. It was found that corrosion resistance of the irons was improved after destabilisation. The 25wt.%Cr showed superior corrosion resistance than the 18wt.%Cr iron due to greater residual Cr in the matrix to encourage passivity.
Flow Curves Prediction of Heat Treated Boron Alloy Steels for Hot Stamping Process
Authors: Srithananan Prapatsorn , Kaewtatip Pongpan , Uthaisangsuk Vitoon
Published: August 2015

Automotive parts made of ultra-high strength steels (UHSS) have been increasingly produced by hot stamping or press hardening of boron alloy steel. In case of novel hot formed components with tailored properties, different heating cycles needed to be applied for different zones, in which varying microstructure characteristics were generated. Mechanical properties of these parts were thus precisely controlled by the microstructure constituents. In this work, stress-strain behaviors of a boron alloy steel undergoing different heat treatment conditions with respect to that modified hot stamping procedure were predicted. Firstly, boron alloy steel sheet specimens were heated up to the austenitization temperature. Afterwards, they were abruptly cooled down to the bainitic temperature range, held for different holding times and finally cooled to room temperature. The microstructures obtained from each condition were characterized by optical microscope (OM) using color tint etching. The stress-strain responses of all generated microstructures were determined by tensile test. By the modeling, flow curves of the individual single phases were described taking into account a dislocation theory based model and their chemical composition. Subsequently, effective flow curves of the heat treated boron alloy steels were calculated by means of the isostrain and non-isostrain method and were finally compared with the experimentally determined curves.
Influence of Flux-Core Arc Welding Parameters on Erosion Resistance of Stellite 12
Authors: Lertvijitpun Pisak , Promdirek Piyorose
Published: August 2015

Due to high wear resistance, Cobalt-based alloys, such as Stellite12 (52Co30Cr8.5W), have presently been used as materials for hardfacing in several applications. Thermowell, a protecting part for thermocouple in petrochemical production, is also coated by Stellite12. Because of high deposition rate, the flux-core arc welding (FCAW) method was selected to be hardfacing process in the research. However, their welding parameters should be exactly controlled in order to obtain desired properties, depending on the microstructure of this material. The objective of this experiment is to study the influence of the FCAW parameters on the erosion resistance of AISI 304 (Fe-18Cr-8Ni-0.06C) welded by the cobalt base alloy filler, Stellite12 (Co-30Cr-8.5W-1.5C) as the hardfacing layer. The studied parameters were welding speed in the range of 2.1-8.5 mm s-1, and wire feed speed in the range of 42.3-67.7 mm s-1, leading to different heat inputs and cooling rates. The erosion resistance was investigated by using solid particle erosion test rig at ambient temperature. Surface characterization was then carried out by SEM equipped EDX and XRD. The results showed the relationship between erosion resistance and microstructure in welding and HAZ zone. The erosion resistance was depended on the formation of interdendritic phase in the welding zone. According to the surface examination, it was found that the formation of interdendritic, including size and shape played an important role on the erosion resistance. The heat input and cooling rate concerned with welding parameters was further discussed with the erosion behavior in this research.Keywords Stellite12, Cobalt base alloys, Flux-core arc welding, FCAW, Erosion-resistance
New Generation Devices for Lubricant Consistency Testing
Authors: Molenda Jarosław
Published: August 2015

Plastic lubricants represent a large group of lubricants that are widely used. Structurally, they are complex colloidal systems and are included among non-Newtonian fluids. They consist of oil basestock, a selected thickener, and a set of improvers. A significant role in the spatial structure of lubricants is played by the intermolecular van der Waals forces between the major components, namely between the basestock and the thickener. However, the spatial structure of the thickener is largely maintained by intermolecular forces other than van der Waals forces, in particular: dipole-dipole force (Kesson effect), dipole-induced dipole attraction (Debye effect), and momentary dipole-induced dipole force (London effect). The result of these types of forces is an adequate lubricant structure, which is responsible for rheological properties and texture [1-3].
Analysis Method for Finding the Sources of Failures in Circuits with a Frequency Converter
Authors: Mroczkowski Paweł , Neska Mirosław
Published: August 2015

The dynamic development of devices that use electrical and electronic components makes it necessary to eliminate sources of interference occurring in circuits with systems of this type. These disturbances adversely affect the correct functioning other systems that work together as a network, as well as equipment located in neighbouring systems. The article presents a method of the analysis of the sources of faults occurring in electrical circuits, using a frequency converter. The discussed principle of the operation of the frequency converter and the impact of disturbances generated by these installations are presented in this article. The evaluation methodology of the installation is presented using the requirements of the Harmonized Standards and the authors’ own solutions. The verification of the method was conducted by applying it to a real electrical circuit. The potential sources of electrical faults were identified that were caused by the frequency converters and its circuit. The developed and presented analysis method of the faults sources can be used for evaluating other circuits of this type in which one of subsystems is a frequency converter circuit.