Advanced Materials Research Vols. 452-453

Abstract: This article introduces the design features of original loading mode of MPS coal mill and proposes that using technology of electro-hydraulic proportional to improve the loading mode. The original loading mode exists many defects. The improvement combines the hydraulic loading system with electronic technology so that the deficiencies of original system are solved and the automatic degree of coal mill loading mode is improved.

Abstract: In this paper, non-silicon steel sheets were produced by both twin-roll casting method and conventional process. Orientation characteristics and texture evolution of the sheets during casting, cold rolling and recrystallization annealing were investigated for comparison. It was found that the subsurface of twin-roll casting strips are characterized by weak {100} orientation while the central layer by random orientation. Twin-roll casting process can decrease α fiber (//RD) and increase γ fiber (//ND) during cold rolling process. Consequently, the η fiber (//RD) favorable for magnetic properties of non-silicon steels is enhanced and the detrimental {111} component is suppressed after annealing.

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 TixPy. Vickers hardness of composites increases with increase milling time and addition of CPP contents. Biocompatibility of CPP added Ti-Nb-Mo alloys were improved.

Abstract: By using butyl titanate as the main material, the nano-TiO2/μm-SiC composite particles were prepared in acidic abundant aqueous solution at low temperature. The properties of the composite particles, including surface morphology, the phase composition of the coating layer, were characterized by SEM, XRD and XPS. The results show that the surfaces of composite particles were rougher after nano-TiO2 coating. Compared with uncoated powders as filler, the weight loss of composite coatings decreased by 43%, when the composite particles were filled in wear-resistant coatings based on the silicone modified epoxy resins.

Abstract: For ICT wide fan-beam scanning, there is a geometrical supposition that the object rotation center and the radiation source center intersect the image reconstruction center. In practice, the existing intersection deviation has influence on the image reconstruction precision. The image reconstruction mathematical model for shifted rotation center was established, and the relationship between the deviation error and reconstructed image precision was studied by simulation. As a result, for 512×512 CT reconstructed image, there is no distinctive difference between the reference image and the reconstructed image with eccentricity 0.1 pixels; however, with 0.2 pixels or more, the difference is obvious. So, for 512×512 CT image, the maximum permissible deviation of the rotation center is within 0.1 pixel dimension.

Abstract: In order to figure out whether Gallium works in the superalloy K444, its composition had been modified by adding about 0.003 wt.% and 0.01 wt.% Ga, respectively. Mechanical properties of the modified superalloy K444 were investigated by using scanning electron microscopy (SEM) after standard heat treatment. Gallium had no significant effect on the tensile strength at room temperature and 900 °C. Gallium had a little effect on the tensile plasticity at room temperature and 900 °C. The plasticity is better in the modified K444 alloy containing 0.003wt. % Ga, however, the plasticity became worse in the alloy containing 0.01wt. % Ga. As for plasticity, the optimum Gallium content should be 0.003 wt. % for the superalloy K444.

Abstract: The gelcasting technique was used to fabricate 95 alumina ceramics green bodies. The gel system based on MAM-MBAM was low-toxicity in this study. The green bodies and the sinter obtained with solid content of 55vol% had high strength, density and quality. The influences of the monomers mole ratio (MAM/MBAM) and the monomers content (MAM and MBAM) on the compressive strength of green bodies, the solid content on the density, compressive strength and the shrinkage rate of green bodies were also discussed. The experimental results showed that the best mole ratio of MAM/MBAM was 12/1. Compressive strength increased with the increase of monomers content (MAM and MBAM). The microstructure of the green bodies indicated that the ceramic powders were connected by polymeric networks, and the ceramic powders in the green body distributed homogeneously and compactly.

Abstract: The thickness of thin laser cladding coating is evaluated with surface ultrasonic wave based on denoising with wavelet analysis method. Two surface ultrasonic wave transducers with 5MHz frequency, which are employed as a transmitter and a receiver, are employed to detect surface ultrasonic wave signals, and cross correlation function is used to determine the difference in time between signals. Results show that the velocity of surface ultrasonic wave propagating in laser cladding Fe314 alloy coating decreases as the thickness of coating increasing, the microstructure of coating is the main reason for noise, the signal-to-noise ratio increases after denoising with db4 wavelet, the result of coating thickness and the difference in time is fitted with polynomial, and the fitting formulas are obtained responding to initial signal and denoising signal, respectively. Based on metallographic analysis result, this method is considered to be evaluated the thickness of thin laser cladding Fe314 alloy coating and the accuracy can be improved based on denoising with db4 wavelet.

Abstract: The DZ417G alloy with different proportion of recycling material was fabricated by directional solidification, and its microstructure and mechanical properties were investigated. The results show that the microstructure of the directionally solidified alloy changes little, which indicates the recycling material has little effect of on the alloy. However, the ductility of the directional solidified alloy with different proportion of recycling material changes greatly. With the increase of the recycling materials, the mechanical properties of the alloy decrease firstly and then increase a little and decrease at last. But the strength of the alloy almost has no change. The alloy with 70%recycle material has the relative better mechanical properties.