Advanced Materials Research Vols. 146-147

Abstract: Titanium alloys are commonly used in biomedical application in hard tissues replacement especially for knee and hip implants. Surface modifications are required prior to diamond coating process for improving the tribological and wear properties of the titanium alloy. In this study, experiments were carried out to investigate the effects of different pickling times as well as temperature on the adhesion strength of oxide layer formed on the Titanium alloy after oxidation process. The aqueous acid solution of HF and HNO3 was used as a pickling solution. The chemical pretreatment was carried out at 4 levels by varying the pickling time as well as temperature. All treated samples were thermally oxidized in a fixed parameters at 900 °C for 25 hours. Surface morphology, oxide layer thickness and adhesion strength were measured after each step using FESEM and Blast Wear Tester (BWT). It was revealed that the thickness of oxide layer increases with pickling time but the adhesion strengths become weaker. It was also found that the adhesion strength of oxide layer formed on Ti substrate surface increases with the increase of temperature while the thickness of the oxide layer decreased within 40oC pickling temperature.

Abstract: In this article, the sludge-based activated carbon was prepared by the sewage sludge from the municipal wastewater treatment plants with ZnCl2 as the activator. The concentration of the activator was 30% and the pyrolysis temperature and duration were 500°C and 1 hour, respectively. The yield of sludge-based activated carbon was 30.14% with 4.66% ash. Under the best preparation condition, carbon content would be highest and the pore structure would be clear. The sludge-based activated carbon was mainly composed of mesopores. The main adsorption peaks of the sludge-based activated carbon were C-O-C (1078.3 cm-1), C=C（1568.7 cm-1）and –OH（3190.9 cm-1）groups.

Abstract: To improve the wear resistance of Titanium alloy, TiAl intermetallic claddings were fabricated on TC4 substrate using laser melting deposition technology. Optical microscope, scan electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction meter were applied to investigate the deposited TiAl layer and their interface with substrate. Using hardness tester and M-2000 wear testing machine, hardness, frictional coefficient and wear resistance of the TiAl layers and TC4 alloy were tested. It was indicated that the deposited TiAl layers were well integrated with TC4 substrate, γ-TiAl and Ti3Al dual phase microstructure was formed in the deposited layer. With higher hardness and lower friction coefficient, the deposited TiAl layer improved the wear resistance obviously comparing to TC4 titanium alloy substrate.

Abstract: Based on the cooling parameters of the mold copper plate for slab continuous casting in a steelmaking plant, the three-dimensional calculating model of the copper plate was established, and three-dimensional distributions of temperature, thermal stress and strain were simulated numerically by using finite element method (FEM). The maximum deformation of the mold copper plate, the highest temperature and thermal stress were obtained. This research is useful for the structure design of the mold.

Abstract: Effect of cryogenic treatments on mechanical properties of 2A11 aluminum alloy were studied. Cryogenic box with program control and electrical resistance furnace were employed to perform cryogenic treatment processes as well as heat treatment processes. Impact tester, tensile tester, three-coordinates measuring machine, high precision caliper and standard metallography were used to carry out tests. The influences of different process parameters on mechanical properties of 2A11 aluminum alloy were compared, and the results showed that cryogenic treatment could improve mechanical properties of 2A11 aluminum alloy. The dimensional stability increases after cryogenic treatment once, and increases further after cryogenic treatment again.

Abstract: In this paper, the sound absorption properties of aluminum sponges manufactured by infiltration process have been studied. The results show that the sound absorption factor α changes in function of pore size. Additionally, the sound absorption factor α was sensitive to the frequency range measured and it was depending of the thickness sample. It was found that the interconnected porosity plays an important role increasing the sound absorption properties of the aluminum sponges studied.

Abstract: In aluminum alloy chemical plating process, temperature is one of the most important factors which directly affect the coating speed and quality. With the change of temperature with speed, so temperature is an important factor which affect the deposition speed. Therefore, to measure and study the influence on temperature to the quality of coating and plating speed is of important theoretical and practical significance. Using scanning electron observe the surface morphology of coating. Spectrum analyzer detects the surface content of Ni- P; then corrosion resistance of coating is detected, and thus the optimum temperature is determined.

Abstract: By means of the thermodynamics analysis of inclusion modification in the process of calcium treatment, and the advantage area chart of calcium, aluminum, sulfur, oxygen activity in inclusion midification, this paper analyzes the effects of molten steel temperature, aluminum activity, sulfur activity and other factors on inclusion modification. After calcium treatment, inclusions in high-quality carbon steel S48 will become massive or globular calcium aluminate, MnS inclusion and the composite inclusions of MgO·Al2O3 in kernel and CaO·Al2O3 in shell.

Abstract: The aging hardening behaviors of Al-8Si-3%Cu (wt%) and Al-3Cu (wt%) alloys have been investigated. Samples were solution treated at 500 for 24 h followed by water quenching before aging. Hardness has been measured for quenched samples aging at 150°C. Strong age hardening occurs for Al-3Cu alloy and hardness increases by about 60% after peak aging. There is a hardness decrease in the early aging stage of Al-8Si-3Cu alloy and hardness increases by about 15% after peak aging. The age precipitation behaviors have been analyzed using DSC and TEM. Effects of microstructure characteristics on age precipitation and age hardening response of Al-8Si-3Cu alloy have been discussed.

Abstract: Ti-6Al-Mo-Fe alloys were prepared by blended elemental powder metallurgy process. In this paper, the mechanical properties and microstructure of Ti-6Al-Mo-Fe alloys sintered from the powders ball-milled for various periods of time were investigated by means of contrition behavior testing, X-ray diffraction, scanning electron microscopy. With an increase in ball milling time form 1h to 10h, the microstructure evolved into a fine β phase within the α matrix. For the Ti-6Al-Mo-Fe alloy, the yield strength and elongation increase as the milling time is prolonged. It was found that the bulk alloys made from the powders ball milled for 6 h exhibited relatively high elongation of 17.8% and high yield strength of 914 MPa.