Applied Mechanics and Materials Vols. 446-447

Abstract: A well adherent copper deposit on the Mg alloy (AZ31) can be obtained with a pretreatment with galvanostatic etching then followed by copper electrodeposition in an alkaline copper-sulfate plating bath. Experimental results show that the effect of galvanostatic etching on copper electrodeposition depends strongly on potential variation during anodic etching period. Oxygen-rich Cu and Mg layers were observed in the initial stage of galvanostatic etching. However, increasing the gavanostatic etching period to the potential plateau of its anodic polarization curve, the oxygen-rich Cu and Mg layers were almost removed and an activated surface of AZ31 can be achieved, which is suitable for Cu electrodeposition in the alkaline Cu-sulfate plating bath. The above-mentioned results were evidenced from the microstructure study with scanning transmission electron microscope.

Abstract: The effect of specific absorbed energy on pultruded profile and thin-walled aluminum composite square cross-section tubes were studied via experimentally. The type of strand mat E-glass reinforced polyester resin was conducted in this study. The specimens of square pultruded and thin-walled wrapped strand mat E-glass composite were compressed under quasi-static of obliquely loadings from the top moving plat platen. For each specimen of composite tubes, triggering mechanism was applied on frontal end top of the tube to obtain the progressive failure throughout the crash event. The pultruded profile tube wall-thicknesses of 2.1 mm and thin-walled aluminum 1.9 mm thickness wrapped 3 layer woven fabric were examined, and the effects of crushing behaviors and failure modes were discussed. Results showed that the tubes energy absorption capability was affected significantly by different type of composite made in term of internal energy.

Abstract: This paper present on discusses the effect of crashworthiness parameters on pultrusion and hybrid laminated composite square tubes via experimentally. The wall-thicknesses of 2.1 for pultrusion and 1.6 mm aluminum wrap 1 layered were examined at the material fiber type of E-glass reinforced polyester resin of square cross-section subjected to axial quasi-static loading. Comparison has been made for both of type of composite material. During experimental observation, some of crushing modes on stages were identified as initial peak load stage, progressive crushing stage and compaction zone stage. The effects of crushing parameters and failure modes were analyzed and discussed. Results showed that the tubes energy absorption capability was affected significantly by varying of different type of composite in terms of composite fabrication and variable aspect of cross-section. It is also found that different type of fabrication on different manufacturing process of composite reveal in terms of internal energy during crushed events.

Abstract: The dynamic recrystallization behavior of TC21 alloy during hot compression deformation was investigated at 870~990 °C and strain rate of 0.001~10 s^-1 on a Gleeble-3500 thermo-simulation machine. The results show that dynamic recovery and dynamic recrystallization occurs during hot deformation. As the deformation temperature increases and strain rate decreases, the softening caused by dynamic recrystallization is more obvious. According to the relevance of flow stress, strain rate and deformation temperature, the dynamic recrystallization activation energy is obtained. The constitutive equation and dynamic recrystallization kinetics motel are set up through analyzing and calculating the data of thermo-simulation.

Abstract: Cast aluminium alloy 354 finds extensive applications in the automobile and aerospace industry due to its attractive combination of mechanical properties and excellent castability. A high fatigue strength value is desirable for these applications. The present study explores the possibility of improving the fatigue life of cast aluminium alloy by subjecting it to Hot Isostatic Pressing (commonly known as Hipping). A three parameter Weibull analysis of the fatigue test results was carried out for both Hipped and Non-Hipped samples. The Hipped samples showed an improved fatigue life compared to the Non-Hipped samples.

Abstract: Wear by slurry abrasion is very expansive problem that must be taken into consideration while selecting the material for the transportation of slurry through pipeline. Abrasive wear generally occurs when abrasive slurries come in contact with the industrial engineering components or slurry transporting pipes. The abrasive particles carried by slurries eventually remove the material from the encountering surfaces which results in the early failure of the component in service. In present investigation an attempt is made to study the effect of load, slurry concentration, sliding distance on the abrasive wear behaviour of mild steel. The slurry abrasion experiments were carried out using slurry abrasion test apparatus with silica sand slurry. The findings of the present investigation indicate that slurry abrasion volume increased with slurry concentration, load and sliding distance, although the magnitude of increase was different in each case. The SEM observation of worn out surfaces revealed micro ploughing and micro cutting as wear mechanisms.

Abstract: The world is moving towards miniaturization of all systems to conserve space and energy. In this experimental investigation, small holes of 0.5 mm diameter were drilled in Ti-6Al-4V plates of thickness 0.4 mm. L18 orthogonal array, the signal to noise (S/N) ratio, and the analysis of variation (ANOVA) were employed to analyze the effect and contribution of process parameters, namely, spindle speed, feed rate, and the use of different lubricants. Drilling experiments were performed in dry, air cooled and wet lubrication (palm oil). Tool wear and hole circularity were evaluated for each machine setting using a Scanning Electron Microscope (SEM). Optimization was performed using Taguchi method and Grey relational analysis. The outcome of this study showed that palm oil can be used as an effective lubricant in order to minimize tool wear and circularity error. Multi performance optimization revealed that feed rate and lubrication were the most significant parameters in controlling circularity and tool wear.

Abstract: Wurtzite type Zn_1-xNi_xO (x=0-0.10) nanoparticles were synthesized by a chemical method via an amorphous polymer precursor. The precursors were derived by a novel process involving a reaction between aqueous solutions of metal ions (Zn²⁺and Ni²⁺) and a freshly prepared solution of poly-vinyl alcohol (PVA)-sucrose under constant stirring at 60-65°C. Structural and magnetic properties of the recrystallized Ni-doped ZnO nanoparticles, obtained after heat treating the corresponding precursors at selected temperatures, were studied in detail. X-ray diffraction (XRD) reveals an increment in the lattice parameters and lattice volume in the doped ZnO samples, confirming the incorporation of Ni²⁺ ions in the ZnO host lattice. All doped samples showed room-temperature ferromagnetism (RTFM) with an increasing saturation magnetization with the increase in Ni doping in the otherwise non-magnetic ZnO. The studies reveals that the observed ferromagnetism is purely intrinsic in nature and it occurs due to the hybridized p-d exchange interaction between magnetic polarons via vacancy mediated defect states inside the crystal lattice.

Abstract: Present work is devoted to phase composition research, structure and microhardness of structural steel 34CrNi1Mo after electrolytic-plasma processing in a cathode heating mode. Technology of electrolyte-plasma hardening provides reliable quality and the required mechanical properties of the products which are often subjected to wear and temperature-force actions. Results of microscopic researches and X-ray structure analysis are presented in this work. It is established that microstructure of steel detail modified layer being processed in electrolytic plasma at a temperature of 850 °C during 5 minutes, is generally represented by martensite quenching. The phase composition of steel 34CrNi1Mo after electrolytic-plasma carburization is presented by structure of α-Fе phase and carbide phases Fe₂C, Fe₃C. Surface microhardness increases more than by 2.5 times in comparison with a reference value.

Abstract: For the 6063 aluminum alloy spray quenching process, respectively establish finite element model of upper, lower nozzle jet impact and water area and meshing in the Gambit. Import into fluent software for cooling numerical simulation, getting the upper and lower nozzle’s pressure contours , velocity contours , heat transfer coefficient curve and water area’s velocity contours and heat transfer coefficient curves. Analysis the various contours and the heat transfer coefficient along the aluminum plate surface radial distribution: upper nozzle’s heat transfer intensity is not in stationary point and near its both sides; Lower nozzle’s contours and heat transfer coefficient has a certain similarity with the upper nozzle, but the maximum heat transfer intensity is at stagnation point; Water area‘s heat transfer coefficient fall faster at the entrance and maintained at a constant value finally. Put heat transfer coefficient as a boundary condition into the ansys software to simulate the three dimensional temperature field of quenching process and analysis the temperature field contours in different time: the biggest speed is 36°C/s during the process of quenching, appearing in the high temperature range, namely deformation sensitive areas, therefore it most likely to occur deformation at the beginning of the quenching profiles.