Advanced Materials Research Vols. 399-401

Abstract: The monosaccharide was derived from α-naphthylamine and separated by high performance capillary electrophoresis in the borax buffer solution as carrier. The standard electropherogram of monosaccharide was analyzed. Polysaccharides with different purity from maize pollen were hydrolysised into monosaccharide and treated by the same method. The monosaccharide composition of polysaccharide was obtained.

Abstract: Ti-6Al-4V ELI (Extra Low Interstitial) alloy have been widely used as alternative bone due to its excellent biocompatibility, although it still has many problems such as high elastic modulus and toxic. Therefore, biomaterial with low elastic modulus and nontoxic has to be developed. In this study, the raw materials which are nontoxic elements such as Nb and Mo were mixed and milled in a mixing machine (24h) and a high energy mechanical ball milling machine (1h, 4h and 8h) respectively. Ti-Nb-Mo-CPP composites were fabricated by spark plasma sintering (SPS) at 1000°C under 70MPa using mixed and milled powders. The effects of CPP contents and milling time on biocompatibility and mechanical property have been investigated. By X-ray diffraction (XRD), chemical reaction during the sintering was occurred and revealed new phases, Ti2O, CaO, CaTiO₃, and Ti_xP_y. Vickers hardness of composites increases with increase milling time and addition of HA contents. Biocompatibility of HA added Ti-Nb-Si alloys were improved.

Abstract: The desired phase-transition temperature and enthalpy of phase change materials are different in different application fields. When the composite way is reasonable, the phase-transition temperature and enthalpy of phase change can satisfy the demand of PCMs using in clothes. Based on The theory of eutectic system and the Schroeder Formula, the lowest eutectic point was computed by using MATLAB software in this paper, and then the enthalpy of phase change was also compared in order to get the best proportion of PCMs.

Abstract: The effects of drying methods on thermal-oxidation degradation and ageing behavior of nature rubber (NR) was investigated using Fourier transform infrared/Attenuated total reflection (FTIR-ATR) and thermogravimetric analysis. Examining the samples of thermal-oxidation ageing for 24h by FTIR-ATR spectroscopy allowed appearance of obvious carboxyl absorption of hot-air drying NR at 1723cm-1, decay of methylene stretch and C=C plane stretch during thermal-oxidation ageing process, to be monitored. TG and DTG were used to determine thermal-oxidation degradation temperature in air atmosphere and active energy using Coats-Redfern equation. Showed from the results, the degradation temperature and active energy of microwave drying NR was higher than hot-air drying, thermal-oxidation resistance was more excellent by FTIR analysis, indicating a higher thermal-oxidation stability of microwave drying NR.

Abstract: Zirconia-mullite nanocomoposites were prepared from TiO₂-doped Si-Al-Zr-O amorphous bulks according to a two-step heating treatment between 880 and 1250°C. Effects of TiO₂ amount and heat treatment conditions on the mechanical properties have been investigated. The fracture toughness was much more affected by the heat treatment processing than by amount of TiO₂. With increasing amount of TiO₂ (2.5~10 wt %), the fracture toughness gradually decreases. Nucleating temperature and time and crystallization temperature and time are interrelated. The fracture toughness of the sample with 5 wt% TiO₂ nucleated at 920°Cfor 2.0 h and crystallized 1150°Cfor 4.0 h is 7.48 MPa•m^1/2.

Abstract: The effect of discharging cycle, voltage, capacitance and time on solidified microstructure of semi-solid slurry of AZ91D alloy treated with Low-Voltage Electric Current Pulse(LVECP) was investigated in this paper. The experimental results show that primary grains of AZ91D alloy were refined apparently, the morphology dendrites of α-Mg were changed by electric current pulse and the nondendritic structure of semi-solid slurry of AZ91D alloy could be obtained with appropriate processing parameters. The decrease of discharging cycle and the increase of discharging voltage and time to prepare semisolid slurry by LVECP discharge promotes the formation of fine α-Mg grains. It is proposed that LVECP treatment created a new dynamic factor for nucleation so that the number of nuclei increased, which restrained the formation of large primary α-Mg dendrites and created a base to form spherical crystals of primary α-Mg. The stronger temperature fluctuation in the melt with many rosette primary α-Mg caused by LVECP discharge and the remelting of the secondary arm roots in the same time are the most important reasons for formation of spherical primary α-Mg grains.

Abstract: In the present paper, hot uniaxial compression at elevated temperatures on the samples which had been hot isostatically pressed to 70%-100% relative densities was carried out to investigate the deformation behaviours of porous Ti-6Al-4V alloy. The results show that the flow stress and densification of Ti-6Al-4V alloy have a greater sensitivity on the deformation temperature and strain rate. The flow stress will increase as strain rate increases at the same temperature and the increasing of deformation temperature can lead to a decline in the flow stress at a specific rate. As the deformation temperature rises or the strain rate decreases, the relative density of compressed samples are higher. Moreover, the initial density affects the thermal deformation of powder compact to a certain extent. At the same strain, the greater the initial relative density of Ti-6Al-4V alloy is, the greater the flow stress will be. The flow stress sensitivity to relative density is much less than that to the temperature and strain rate. In addition, the higher the deformation temperature is, the more sufficient the process of alloy spheroidization will be. As the deformation rate decrease, the lamellar organization in the titanium alloy will convert into the equiaxed grains. The lower the deformation rate is, the more obvious the phenomenon of alloy globalization will be. There is not significant transition of the widmanstatten structure in the sample compressed for 2mm. When the sample was compressed for 5.6mm, a few equiaxed grains occurred. When the sample was compressed for 7mm, a large number of equiaxed grain occurred.

Abstract: It commences that optimize and design the billet of the medium slab, analyzes various factors that influence plate yield, and proposes the method of the reasonable billet design. Then it anticipates each shift team production plans according to each reasonable combination of the different billet. It is based on the spot production experience of plate, and guarantees the safety of equipments, with attainment of high yield, to optimize design of plate deformation. It imitates calculation the microstructure organization of the medium plate after rolling and cooling by means of researching on the rule of austenite recrystallization. The calculation of the rolling power adopts to consider the variety of the recrystallization in austenite the correction function, improve the accuracy forecast of power and energy. The simulation and calculated results will be showed by means of tabular form or graphic formats.

Abstract: Powder metallurgy (PM) nickel-based superalloy is regarded as one of the most important aerospace industry materials, which has been widely used for engine components. As the demands of the service performance increase, the surface characteristics are becoming more and more important. However, the machined surface of PM nickel-based superalloy is easily damaged due to its poor machinability. A series of milling experiments in a wide range of speeds were carried out to investigate the effects of dry milling parameters on the surface characteristics of PM nickel-based superalloy. The machined surface is evaluated in terms of surface roughness and work hardening. The results show that, milled surface characteristics of PM nickel-based superalloy are sensitivity to the cutting speeds. The machined surface roughness increases with increase of the cutting speed, but with further increase of cutting speed between 70 to 90 m/min and 150 to 170 m/min two decreases in surface roughness appear. For work hardening, it can be seen that the machined workpiece surface hardens seriously.

Abstract: As an important Solid Free Form Fabrication (SFF) technology, three-dimensional printing (3DP) has become popular in applications due to its properties of rapid prototyping, no pollution, and high productivity. Based on the experiment platform of ZP310, this paper investigates that powder layer thickness and blinder saturation level for different location of parts placement have effect on the part surface topography and forming accuracy, the location of parts placement includes right, middle and left, respectively, which represents the different face contact to the bottom of manufacturing box. The experiments show that: when the left of part is placed to contact to the bottom of manufacturing box, the powder layer thickness is 0.1 mm and the binder saturation level is 70%, the best surface topography can be obtained.