Abstract: LC4 aluminum alloy samples were treated by micro-arc oxidation (MAO) to produce trace loose layer film to improve the surface properties. The mechanical characteristics, high temperature erosion performance, structure and composition were investigated by strength tester, high flame erosion, scanning electron microscopy and energy-dispersive X-ray spectrometry. Compared to the untreated aluminum alloy, MAO coatings have good mechanical performance with tensile strength bigger than 18MPa and is intact with 20s heat ablation of 1900°C.
Abstract: This article presents a detailed research on pulse electrical parameters for non-cyanide electroplating copper plating on stainless still substrate. The study was made about the effect of the current density, duty ratio and frequency on the surface morphology, thickness and uniformity of the deposited layers. The surface morphology was examined by MIT 300 metallurgical microscope and the thickness of copper coatings was examined by TT260 coating thickness gauge. Current density 0.4A/dm2 is the optimum current at which the best uniform coating can be formed.
Abstract: Copper electroplating films were prepared on 20# steel by four different power modes which are direct current plating, single polar pulse plating, bipolar pulse plating and bipolar pulse plating with magnetic field. The electrochemical performance was investigated in 3.5% NaCl solution by means of potentiodynamic polarization measurement. The morphology and micro structure were characterized by scanning electron microscope and X-ray diffraction. It is proved that the magnetic field is responsible for the improvement of the performance of copper electroplating films.
Abstract: Engineers, biologists and surgeons face a special task when they design procedures, components and systems to replace damaged tissues beyond any limits, caused by disease or trauma. It has been proven that titanium and its alloys have an excellent biocompatibility, that’s why many studies have been made on them, in order to enhance their biomedical applicability. In this paper, the wear behavior of two new titanium alloys, Ti12Mo and Ti25Nb25Ta , have been tested in biological conditions
Abstract: The cyclic oxidation behavior of Co-10Cr-5Al alloys in atmosphere at 700 °C was investigated. The addition of 0.3 at.% Y changed the oxidation behavior from the approximate parabolic rate law to complex mode. The scale grown on the surface of Co-10Cr-5Al cracked seriously, while the oxide scale the Y doped alloy had better adhesive property. Yttrium doped in the sample promoted the forming of continuous Al2O3 layer and decreased the oxidation rate of Co-10Cr-5Al alloys.
Abstract: The 0.5-3.0 mol% Er3+-Ce3+ co-doped TiO2 powders have been prepared by sintering the hybrid materials Er0.5Ce0.5(AA)3phen-doped TiO2/PMMA, which were prepared by sol-gel method, using the modified titanium (IV) n-butoxide [Ti(O-Bu)4-x(AAPhen)x] as precursors which were given by the chelate reaction between Ti(O-Bu)4, AA and Phen at 70°C. The hybrid matrix TiO2/PMMA improved the dispersion of Er3+, which caused an enhancement in the photoluminescence (PL) peak intensity at 1.53 mm of the 1 mol% Er (AA)3phen-doped TiO2/PMMA powders sintered at 700 °C of about 23 times higher than that only had TiO2 as its matrix. When co-doped with Ce3+, the above ratio of the PL peak intensity was raised to 75 times, which illustrated the obvious sensitization and dispersion effects of Ce3+ on Er3+.
Abstract: The main aim of this scientific research is to assess the contribution of surface layers of hardened steel by determining the experimental measurement of cutting forces in the turning technology with the coated carbide cutting insert. This experimental study is a continuation of the solutions of grant VEGA no. 1/9428/02 titled “The technological heredity of the machined surfaces - surface integrity”. The aim of the present article is to focus scientific research on the impact of the various components of cutting forces in turning of 1.4301 steel at the outer longitudinal turning with wiper cutting coated cemented carbide insert. This scientific paper, together with published results is a basis that will enable optimizing the quality of turning process of steel materials used for special applications or automotive parts with their dominant functional areas.
Abstract: The paper aims to study the influence of high temperature processing on the substructure of laser shock processed titanium alloy. The titanium alloy specimens were first treated by laser shock processing (LSP), then treated at 700°C for three hours and air cooled to the room temperature to investigate the influence of the high temperature processing. To evaluate such influence, the hardness and substructure on the surface were investigated by micro hardness tester and transmission electron microscope (TEM), respectively. Results show that after three times LSP, the hardness of TC11 alloy was improved by 30.9%. The cause of such an improvement in hardness is that the crystal grains in the surface layer under the shock wave stress were strongly deformed, causing a dynamic recrystallization. The substructure is mainly twin crystals, highly tangled and dense dislocations. After high temperature processing in vacuum, the average hardness is decreased by 12% compared to that of the specimens after LSP. And the substructures are mainly small dislocation, nanocrystalline.
Abstract: The parameter identification of a new hysteretic nonlinear metal rubber damper system is studied in this paper. Firstly, the advantage of the new metal rubber damper which composed by two components is proved by the static and dynamic test comparing to the damper included only one metal rubber. Secondly, the constitutive of bilinear hysteresis model and parameter identification equation are obtained. Then the parameter of the new damper system is identified by generalized least squares estimation. In the last, the simulation result is compared with the real values, it shows that the method is simple, effective, high precision, and it is also reliable and applicable to the corresponding engineering.