Materials Science Forum Vols. 620-622

Abstract: An internal lobe pump is suitable for oil hydraulics of machine tools, automotive engines, compressors, constructions and other other applications. In particular, this type of pump is an essential element of an automotive engine to feed lubricant oil. We perform a theoretical analysis of the internal lobe pump whose main components are rotors. Usually, the outer is characterized by a lobe with elliptical and involute shapes, while the inner rotor profile is determined as the conjugate to the other rotor. Our integrated system, which is composed of three main modules, was developed through AutoLISP using AutoCAD. It generates a new lobe profile, and automatically calculates the flow rate and flow rate irregularity according to the lobe profile generated. Results obtained from the analysis enable the designer and manufacturer of oil pumps to be more efficient.

Abstract: The electrochemical properties of LiFePO4 as a cathode of lithium ion batteries considerably depend on a particle size of LiFePO4 and a condition of carbon coating. In this study, LiFePO4 powders were prepared using ultrasonic spray pyrolysis method, and then LiFePO4/C composites were made by infiltrating sucrose solution into LiFePO4 powders, drying, high-energy milling and annealing. The effects of high-energy milling were analyzed by comparing with electrochemical properties of powders synthesized without high-energy milling. It was found that the milling process drastically reduced the particle size of synthesized powders and electrical conductivity, and improved discharge capacity, cycle stability and rate performance.

Abstract: Based on the application of slag splashing for building up a protective coating layer on the refractory lining, a technique for comprehensive maintenance of converter refractory linings has been developed in this paper. The effect of slag properties, slag amount, tapping temperature, and lance height on the splashing was investigated by physical model experiments. The facilities and regimes of 50-ton converter at the Long-steel had been modified. At present, the life of converter lining has already reached to 15,000 heats, the productivity reached 87 %.

Abstract: In the present study, poly(ethylene glycol)(PEG) with different molecular weights were blended with different fatty acids: capric, lauric or stearic acid as a thermal energy storage material. Latent heat thermal energy storages properties of the blends were evaluated by using the differential scanning calorimetry (DSC). The thermal analysis indicated that it is possible to obtain homogeneous PEG/fatty acid blends by mixing in the melt and subsequent solidification. The PEG-fatty acids blends had greater enthalpy and exhibited good thermal stability and can be used as a new kind of phase change material for thermal energy storage material for thermal energy storage and temperature control. The heat of transition for PEG10 000/ stearic acid (1:3 w/w) blend was on extremely high level of 253.2 J.g-1 which is 35% more than for pure PEG 10000

Abstract: High-purity aluminum oxide is potentially an attractive implante material for total hip joint replacement, because its biocompatibility, excellent wear resistance, high strength and corrosion resistance. The main problem of alumina is relatively low fracture toughness. Thus, this study is the introduction of ZrO2 as second ceramic phase homogeneously dispersed wihtin an alumina matix. Al2O3/ZrO2 nanocomposites disk is prepared by spark plasma sintering (SPS) method at 1500°C and 50MPa, in vacuum for 5min. Then, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the microstucture and phases of this nanocomposite. Moreover, frexual sthrength of the nanocomposites was meausured as well as hardness and fracture toughness. When the content of ZrO2 is up to 15wt%, the fracture toughness value (8.4MPam1/2), and strength (527MPa) are achieved. This Al2O3/ZrO2 nanocomposites may be served as a tatal hip joint replacement.

Abstract: In order to investigate the feasibility of spray forming process for production of high Si steel sheets, 4.8~6.4%Si steels were prepared by spray forming process using N2 and Ar gases and their cold workability was compared with that of conventional ingot cast samples. Atomizing gas affected significant effect on deposit features, microstructural characteristics and mechanical properties of the spray formed high Si steels.

Abstract: The consolidation process of ultra fine Si powders, generated as by-product during the decomposition process of silane gases, was systematically investigated for use as economical solar-grade feedstock. Si powder compacts were tried to fabricate by a consolidation process without a binding agent and then their density ratio and strength were evaluated. The Si powders in as-received state were not pure enough to be used alone as solar grade feedstock material. After the adequate chemical treatments, a sufficiently high purity above solar-grade was able to be achieved.

Abstract: Ti foil and Ni foil interlayers were selected for the bonding of tungsten to CuCrZr alloy. The effects of bonding temperature on the microstructures and shear strength of the joints were performed. The interfacial bonding mechanism was studied through microanalysis. The results show that Ti foil was transformed into liquid solution and extruded mostly out of the bonding zone at 980°C, the strength of the joints can reach 136MPa due to the chemical and mechanical interfacial bonding. Ni foil was used for bonding of tungsten to copper alloy, the EDS analyses shows that the solid solution Ni(W) and the intermetallic compound NiW2 form in the diffusion layer at 920°C.

Abstract: Mechanical properties of micro-electro-mechanical systems (MEMS) materials are increasingly important with the wide use of miniaturized systems. This paper deals with development of the strain measurement module for micro materials tests. Vision strain method (VSM) and actuating stroke method (ASM) are adopted in the strain measurement module in order to reduce the discrepancies between the measured deformation and actual one in the specimen. With the developed strain measurement system, a number of tensile tests were concluded for 99.9% nickel thin films with the thickness of 500µm. Specimens with various widths from 1 mm to 2mm and with various lengths from 2mm to 4mm were used in the tests. From the experiment, material properties such as yield strength, tensile strength, fracture strength, fracture strain and young’s modulus are analyzed with stress-strain curves of 99.9% nickel thin film.

Abstract: Poly(ether sulfone)s (PES) containing 25-75 mol % valeric acid were prepared with bisphenol A, bis(4-chlorophenyl)sulfone and 4,4-Bis(4-hydroxylphenyl)valeric acid using potassium carbonate in DMAc (dimethylacetamide) at 160 °C. Copolymers containing carboxylacid group were reduced to hydroxy group by BH3 solution 1M in THF and NaBH4 co-catalyst. Sulfonated poly(ether sulfone)s (S-PES) were obtained by reaction of 1,3-propanesultone and the reduced copolymer (PES-OH) with potassium t-butoxide. A series of copolymers were studied by 1H-NMR spectroscopy, differential scanning calorimetry (DSC), and thermo gravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymers with water and methanol. The S-PES membranes exhibited proton conductivities from 1.20  10-3 to 3.40  10-3 S/cm, water swell from 12.25 to 31.50 %, IEC from 0.43 to 0.72 meq/g and methanol diffusion coefficients from 3.60  10-7 to 4.90  10-7 cm2/S at 25 °C.