Abstract: This paper presents the synthesis of a Cu-0.5wt%Nb alloy via mechanical alloying (MA) and subsequent hot pressing. The evolutions of the density, microstructure, microhardness and electrical conductivity of the alloy as a function of the sintering temperatures were investigated. The results show that the microhardness of the alloy decreases with increasing consolidation temperatures, while the density and the conductivity improve. The alloy, subjected to vacuum hot-pressing sintering under 25 MPa pressure and 800 °C for 2h, has a microhardness of 102 HV and an electrical conductivity of 98% IACS. The as processed alloy is characterized by Nb nanoparticles distributed in the submicron sized Cu grains. The microhardness and electrical conductivity of the alloy are closely related with the microstructure, i.e. Cu grain size, as well as the presence and distribution of Nb nanoparticles.
Abstract: Use of correct values of material properties is important in structural analysis. When incorrect values are used in the analysis, engineers may end up with misleading conclusions. The magnitudes of elastic modulus and strength are usually measured from experiments at room temperature. When these values are used in the thermal stress analysis of structures, the results may not be reliable because the magnitudes of elastic modulus and strength depend on temperature. The temperature distribution of HVAC (Heating, Ventilation and Air Conditioning) system was analyzed. The material properties were measured using MTS810 material test system and MTS 651 environmental chamber at different levels of temperature. They were used in the thermal stress analysis of HVAC system. It was found that the results of thermal stress analysis were significantly different from the results using material properties which were measured from experiments at room temperature.
Abstract: NiTi shape memory alloy is an intelligent drive and awareness materials which develop very rapidly and is used in many fields in recent years, whose mechanical properties are not only related to chemical composition, but also closely related to the temperature. This article aims to study the NiTi shape memory alloy wire’s constitutive behavior coupled thermal and mechanical properties at different temperatures. By analyzing the results, the relationship of NiTi shape memory alloy between deformation and the restoring force at elevated temperature is obtained, thus providing a basis for the engineering design and simulation process of NiTi intelligent material.
Abstract: The phase change energy storage aggregate was prepared with the eutectic mixture of capric acid (CA) and stearic acid (SA) as phase change energy storage material (PCM) and waste autoclaved aerated concrete as skeleton. The results showed that the appropriate mass ratio of CA to SA is 9:1, with melting temperature 26.8°Cand latent heat of 96.4 J/g. The optimal load of PCM on waste autoclaved aerated concrete was 55%. In order to reduce leakage and increase strength of the aggregate, slag-water glass-gypsum binder was used for encapsulation, which also helped increase the compatibility with the main building materials. The simulation test showed that the phase change energy storage aggregate possesses good temperature control and energy storage performance.
Abstract: SUZ-4 zeolite was synthesized by the sol-gel technique, followed by hydrothermal process. The effect of the molar ratio of rice husk ash based silicon dioxide to silica solution was investigated. The synthesized zeolite was characterized by XRD, SEM, N2 adsorption and temperature programmed desorption. The results show that the SUZ-4 zeolite was formed for all investigated conditions. However, the formation of MER zeolite occurred as an impurity for the content of rice husk ash higher than 75%. A needle shape crystal with mainly microporous structure is the feature of synthesized SUZ-4 zeolite. The result of temperature programmed desorption indicated that the chemical surface property of obtained SUZ-4 zeolite was weak acid sites.
Abstract: Q345 is a material which is applied widely in wheel loader boom. The loader boom is manufactured by flame cutting process, while the flame cutting is a special process which will change the material mechanic properties. So it is necessary to consider the effect of the flame cutting on the static and fatigue properties of Q345. In this paper, a test about the static characteristics and fatigue properties of Q345 was launched, and the effect of the flame cutting was considered, as the result, the law affected by the flame cutting on the fatigue properties of Q345 was obtained.
Abstract: Wet recycling method was utilized for recycling manganese from waste Zn-Mn batteries to obtain MnCO3. It was indicated that soaking time, the concentration and volume of acid all have great effects on the yield of MnCO3. The productivity of MnCO3 can reach 64.65%, when the concentration of HCl acid is 5mol/L, and with a volume of 40ml, under 180min soaking time. The productivity of MnCO3 can also reach 63.36%, when the concentration of HNO3 is 6mol/L, with 60ml volume by soaking for 80min. Furthermore, LiMn2O4 was synthesized in air atmosphere with the recycled MnCO3 and Li2CO3 under different calcination temperatures. The electrochemical performances of prepared LiMn2O4 were studied and the results present preferable electrochemical properties.
Abstract: AlMg5Si1-xRE (x=0%, 0.9%) alloys were prepared by resistance melting method, and the phases of alloy were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The effects of RE (rare earth) on the corrosion resistance of AlMg5Si1 alloy immersed in seawater in different time were investigated by potential measurements and electrochemical impedance spectroscopy. The results showed that the strengthening phase β (Mg2Si) was short rod like and dispersing distributed in α (Al) in the AlMg5Si1 alloy after adding 0.9% RE. Under the conditions of seawater immersion, the corrosion rate of the AlMg5Si1RE0.9 alloy was less than that of AlMg5Si1 alloy, and the corrosion rate of AlMg5Si1RE0.9 immersed 12h in seawater was the slowest, 5.7 uA·cm-2. The improved corrosion resistance is due to the changes in microstructure and corrosion products.
Abstract: Ti-35Nb-2Zr-0.3O (wt.%) alloy was melted under high-purity argon atmosphere in an electric arc furnace, followed by cold rolling. The effects of deformation process on microstructures and thermal expansion behaviors were investigated by OM, XRD and TMA. Results showed that the stress-induced α" martensitic transformation occurs after cold rolling. The solution treated sample exhibits normal thermal expansion along the rolling direction, and the thermal expansion rate increases with the increase of temperature. After cold rolling, thermal expansion behavior is polarized (negative thermal expansion occurs along rolling direction and normal thermal expansion higher than solution treated sample occurs along transverse direction). The thermal expansion rate along rolling direction decreases with the increase of reduction. The 40% cold deformed sample along rolling direction possesses Invar effect in a temperature range from 25°C to 350°C. The anomalous thermal expansion behaviors of cold rolled samples possibly relate to stress-induced α" martensitic transformation and β <110> texture evolution.