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We present a novel design method of a 6-axis Force/Torque (F/T) sensor with identical stiffness in all directions. In contrast to common F/T sensor designs, the proposed method is an analytical approach to the realization of a desired diagonal stiffness matrix which implies the complete decoupling of the stiffnesses in all directions. The first step of the design is to group the column vectors of a given rank 6 diagonal stiffness matrix into in-plane type and out-of-plane type stiffnesses. Each type of stiffnesses is then synthesized by means of three line vectors and designed as the corresponding serial-chain for a limb of an F/T sensor using only circular hinges. The F/T sensor can be formed by connecting the designed two serial-chains in series. However, for a practical design with minimum structural error and better strength, each of two type stiffnesses is further divided into a set of n separate serial-chains. Finally, the n-sets of serial-chains each consisting of six circular hinges that correspond in-plane and out-of-plane type stiffnesses are connected to the moving platform in parallel to complete the design. The FEM analysis and experiments are conducted to verify the proposed design method.

We report an atomic force microscopy (AFM) based method to characterize the adhesion between metal nanoparticles and carbon support that plays an important role in determining the durability of fuel cells. This adhesion is related to the electrochemical active surface area (ECSA). Force–distance curves measured with a Pt-coated AFM tip on the surface of the support allows us to probe the adhesion between a Pt nanoparticle and the support because an asperity between a Pt-coated AFM tip and carbon support can mimic the nanoscale interface between Pt nanoparticles and carbon. We found that acid-based surface treatment of the carbon support increases the adhesion force by a factor of 4, compared with the as-received carbon support. Meanwhile, surface treatment using acid on the carbon support can lead to a higher ECSA, which is consistent with the higher adhesion force probed with AFM. We attribute the higher adhesion between the Pt probe and the acid-treated carbon to stronger chemical interaction by the C/O functional groups.

Tin has been widely used to solder, tin plated steel, bronze alloy, sputtering target for transparent electrode and chemical additives. It has been widely reported to the recycling technologies for tin scraps because of the scarcity and economic efficiency of the reserve. This study was analyzed by using open/registered patents KR, US, CN, JP and EP related to recycling technologies for processing scrap, sludges, waste fluid for plating process and spent alloy containing tin in between 1970 and 2013. Patents were collected using key-words searching and filtered by filtering criteria. The trends of the patents were analyzed by year, country, appliant and technology.

A single pulse of 0.57–1.1 kJ/0.3 g-spherical Ti -powder in size range of 30–70 μm, using a constant 450 μF capacitor, was applied to produce fully porous Ti - and W -compacts by electro-discharge sintering. Microstructure examination and hardness measurement of the porous Ti -compacts revealed that more stable necks formed with increasing electrical input energy up to 1.1 kJ. On the contrary, W -compacts using rectangular W -powders in size range of 5–15 μm are composed of solid region with micropore and porous layer with weak particle bonding indicating heterogeneous structure. These results suggest that the powder morphology plays a crucial role to control the porous microstructure.

A single pulse of 0.57–1.1 kJ/0.3 g-spherical Ti-powder in size range of 30–70 μm, using a constant 450 μF capacitor, was applied to produce fully porous Ti- and W-compacts by electro-discharge sintering. Microstructure examination and hardness measurement of the porous Ti-compacts revealed that more stable necks formed with increasing electrical input energy up to 1.1 kJ. On the contrary, W-compacts using rectangular W-powders in size range of 5–15 μm are composed of solid region with micropore and porous layer with weak particle bonding indicating heterogeneous structure. These results suggest that the powder morphology plays a crucial role to control the porous microstructure.

최근 글로벌 산업 환경은 원소재 공급의 장기 불안정성과 에너지/환경 분야의 각종 규제가 강화됨에 따라 각 원소별 천연자원, 제련산업, 소재화산업, 전방수요산업 측면에서 자국현황과 국외 현황을 정밀분석하고 급변하는 산업환경에 대응하기 위한 전방위적 전략 구축을 위한 경쟁이 치열하게 전개되고 있다.특히, 자원의 희소성과 소재화 과정에서의 산업기술이 부족한 소재에 대해서 특별히 희유금속(raremetal)으로 규정하고 선진국을 중심으로 자원확보, 산업기술 선진화, 순환산업 활성화 및 인력양성을 위한민간과 정부의 공동 노력이 오랜 기간동안 실행되고있다.우리나라의 경우 그동안 정부주도로 요소기술을 중심으로 한 압축성장 전략을 구사하여 짧은 시간에 전방산업 중심의 급격한 성장을 구현해 냈다. 그러나이러한 성장방식은 근원적으로 국외 원천소재, 원천기술을 도입하는 방식으로 전개되었고 결과적으로 국내 소재산업은 저부가 범용소재 분야로 전락한 반면고부가 원천소재에 대한 국외 의존도가 높아 균형발전에 있어 한계를 가지고 되었다. 따라서, 향후 전방산업분야의 지속적인 성장을 위해서는 소재-부품-제품 산업에서 국내소재산업의 현재 불균형을 개선할필요가 있다.본 기술보고에서는 자원의 희소성과 자원 확보의글로벌 경쟁이 심각한 대표적인 희유금속중 하나인텅스텐에 관하여 텅스텐 자원 현황과 자원보유국 및수요국의 전략과 국내산업 현황 분석을 통해 국내 텅스텐 관련 산업의 문제점을 분석하여 향후 텅스텐 관련 국내산업의 발전 방향에 대하여 기술하고자 한다.

In Vitro Bond strength of base-coated (Y, Fe)-TZPs (yttria and iron co-doped tetragonal zirconia polycrystals) were investigated to evaluate the feasibility for the ceramic bracket applications. Pre-sintered (Y,Fe)-TZP brackets were machined, abraded and spray-coated with granule slurries containing 10~50 wt% of flux. Better adhesion to the base surface of the brackets was observed by raising the amount of flux in the slurries. It may be because of the fusion and the collapse of the granules as a result of the high amount of flux. The one-way analysis of variance indicated that there were significant differences in bond strength measurements between the experimental groups except 30% and 50% flux content groups. The Weibull distribution revealed that 50% flux content group is the best with a high characteristic strength value. Mean ARI values exhibited large differences and ranged from 1.6 for 50% flux content group to 3.0 for non-coated group. Adhesive remnant of adhesive resin was decreased by increasing the flux up to 50%. Reduction in adhesive remnant is likely due to the higher bonding of adhesive resin to granules. No teeth and bracket damages were found in any teeth de-bonded by shear force. The base-coated brackets with higher strength (11.5 MPa) and no adhesive remnant were newly proposed for the orthodontics applications.

The proper control of total impurities and oxygen contents of oxygen-free high conductivity (OFHC) copper prepared by vacuum high-frequency melting technique was studied using Mahalanobis-Distance (MD) outlier detection method as functions of raw material purities, vacuum pressure, melting temperature and holding time. The properties of vacuum-melted OFHC copper was examined by thermo-gravimetric analysis, differential scanning calorimetry, hardness test, macro and optical microstructure analyses and ultimate tensile test. In multivariate systems, the existence of outlier makes it difficult to analyze the system and oultier detection belongs to the most important tasks in experimental data analysis. Mahalanobis Distance is most commonly used as a diagnosis of existance of outlier in multivariate system. The relationship between experiment conditions and total impurities and oxygen contents can be defined with the regression analysis results. At this research, our desirable manufacturing conditions is to obtain the total impurities under 40 ppm and oxygen contents under 5 ppm. After this statistical approach, the suggested minimum maufacturing conditions are the purity of raw material was 4N, vacuum pressure was 10-1 torr, melting temperature was 1150°C and melt holding time was 20 minutes.

In order to enhance understandings of the coating formation in the plasma spraying, an empirical method known as the spot spraying bead formation, was designed. This study is focused on the applicability of the proposed empirical method to explain the microstructural inhomogeneity during the process. Based on the in-flight particle diagnostics using DPV-2000, two different plasma gas compositions were chosen to evaluate the plasma gas effect on the microstructural evolution of Al2O3-TiO2 composite feedstock. A blended NiCr-Cr2O3-Ag-Ca/BaF2 feedstock was sprayed in order to examine the effects of particle parameters on the particle trajectory and the coating microstructures. Through the empirical approach, impacting particle properties and particle trajectory depending on process parameters could be directly shown and coating microstructures could be deduced from the characteristics of the spot spraying bead.

Fine and coarse alumina-titania composite particles were overlaid by allowing the particles to be deposited for a short time without moving a plasmatron [spot spraying bead]. Both the deposition efficiency and maximum deposition rate were measured at the different plasma gas composition. Considering the normalized maximum deposition rate [(maximum deposition rate)x(deposition efficiency)-1], effects of particle size and plasma gas composition on the particle segregation within a cross-section of mass flux could be estimated. Also, particle melting state according to the position within a mass flux at the moment of impact could be also estimated through the investigations of microstructure and phase composition of the spot spraying bead.

The surface of commercial carbon black was modified by pyrolysis of acetonitrile in attempt to obtain the graphitic carbon coating layer. It was confirmed that the surface of carbon black was partially graphitized, having 0.23 of graphitization index and 1.87 nm of mean stack height. From the electrochemical oxidation test of carbon, the carbon-coated carbon black showed higher corrosion resistance than the untreated carbon black although the core of the carbon black support still remained untreated. When it was applied to the support for platinum electrocatalyst, the enhanced stability was observed. From those corrosion tests as well as XPS results, it can be suggested that the partially crystalline graphitic carbon surface facilitates the relatively more reduced surface of platinum.

The environmentally friendly manufacturing process, continuous casting process with small cross sections, is the near net-shaped manufacturing technology used to fabricate copper alloy wires and plates with the required final tolerance and sound quality. Furthermore, the process consumes less energy and discharges less environmental loads because the process can eliminate the need for hot extrusion, hot rolling and heat treatment for production copper alloy wires and plate. In the present study, the effects of a continuous casting speed on the mechanical properties and the microstructure of the nickel-silver (Cu-Ni-Zn) alloy were studied and energy requirements, atmospheric CO2 emission and yield for the production of the Cu-Ni-Zn alloy was investigated quantitatively with respect to continuous casting with small cross sections and conventional material processing including casting, extrusion and heat treatment. The yield for production of Cu-Ni-Zn alloy can be improved above 30% with the application of continuous casting with small cross sections when the productivity is similar. Twice the amount of energy required and CO2 were consumed and emitted in the conventional manufacturing process when the yield of the processes was considered.

The effects of Nd-Fe-B magnet scrap size on extraction behavior were investigated by liquid metal extraction using molten Mg. The magnet scraps with Mg were placed into a stainless steel crucible and then heated to 1,073K for 10 to 50min. The amount of ex-tracted Nd after liquid metal extraction process was increased with an increasing with holding time and scrap size, and the maximum con-tents of Nd in Mg were observed to be about 24.2 wt.% in the conditions of the 5mm sized scrap heated for 50min. It was revealed that Nd oxides existing in the magnet scraps prevent the dissolution of Nd into Mg. Keywords: Extrusion rate, liquid metal extraction, magnesium, Nd-Fe-B magnet, neodymium,. INTRODUCTION Neodymium (Nd)-based magnet materials have emerged as leaders in high-field permanent magnet applications. Since the de-velopment of the iron–neodymium–boron (Nd-Fe-B) permanent magnet in 1980, the production volume of Nd metal has increased dramatically. On the other hand, large amounts of scrap from the Nd-Fe-B magnets are being stockpiled due to the lack of a cost-effective recycling process. Thus, it is crucial to develop a recycling process for the Nd-Fe-B magnets [1-4]. Among the reported, the best separation of rare-earths from the Nd-Fe-B magnets is obtained by sulfuric acid dissolution followed by precipitation of recyclable rare-earth salts [5-7]. However, this process produces large amounts of wastewater including dangerous solutions. Recently, Xu

This study was conducted to observe the influence of oxygen to fuel ratio[O2/H2ratio] of HVOF(High Velocity Oxygen Fuel) process on the amorphous formation and coating properties of NiTiZrSiSn bulk amorphous alloy. The bulk amorphous feedstock was prepared by inert gas atomization. Amorphous contents were followed by differential scanning calorimetry(DSC). Microstructural characterization was done by scanning electron microscope(SEM) and x-ray diffraction(XRD). Mechanical properties were obtained by Vickers microhardness testing and pin on disk wear testing. A maximum 72% amorphous phase could be obtained with an optimum O2/H2ratio. High amorphous content resulted in a low friction coefficient and weight loss than high oxide content coating and fully crystallized coating.

A blended NiCr-Cr2O3-Ag-BaF2/CaF2 feedstock was sprayed using an atmospheric plasma spraying process. Due to the differences in physical and thermophysical properties of each constituent, coating microstructures and resulting coating properties were largely dependent on the interactions between each constituent phase and plasma jet in view of the physics of thermal spraying. Thus, hydrogen gas flow rate was changed to affect the plasma jet characteristics such as gas enthalpy and gas thermal conductivity in this study. According to it, evolutions of chemical composition and microstructures of the as-sprayed coatings were observed. As the hydrogen gas flow rate was increased, Cr2O3 weight fraction was increased with the decrease of Ag and porosity. Vickers microhardness and bond strength of the coatings showed consistent behaviors to the phase composition and microstructures. Friction coefficient and weight loss during a pin-on-disc dry sliding wear test were measured from room temperature to 500°C at the interval of 100°C. Finally, the effects of phase fraction and coating properties on the friction and wear were investigated.

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