Advanced Materials Research Vols. 152-153

Abstract: The Influenceof Rare Earth Element on α—Solidification of A356 Alloy has been discussed in the paper . It is showed by the research, that the condition of interphase is changed by Rare Earth element asymmetry distribution, which influences the process ofαphase growing and facilitates the growth of αphase in sphere, and leads to a optimal Rare Earth quantity for facilitative effect, which is 0.5% in this experimentation, and that αphase grain will be change to small by adding Rare Earth.

Abstract: The Effect of intercritical quencing on microstructure and mechanical properties of ultra low carbon heavy steel plate were studied by utilizing SEM, TEM, tensile and impact tests. The specimens were firstly subjected to an annealing treatment at 930 oC followed by quenching to ambient temperature, then were repeatedly annealing at the temperatures being varied in the range of 600~870 oC, and then repeatedly quenched to ambient temperature in cold water. When the intercritical quenching was just slightly above Ac1, the strength and low temperature toughness were remarkably deteriorated attributing to the massive grain and some twins in the bainite islands. However, the more when the annealing temperature increased higher than Ac1 but still below Ac3, the more regions can be austenized, which cause the average of carbon content in the austenized regions to be relatively low. So it was difficult that these austenite regions changed into twin martensites after interctitical quenched. Then the comprehensive properties including low temperature toughness became good again.

Abstract: The supramolecular interaction of curcumin and RM-β-CD-m was studied by spectrophotometry, and the apparent formation constant for curcumin-RM-β-CD-m complex was determined. The results showed that a 1:1 complex between curcumin and RM-β-CD-m was formed, and the apparent formation constants increase with the increase of reaction temperature. The thermodynamic parameters, standard free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) for complex formation of curcumin with RM-β-CD-m were calculated. ΔG° value indicates that the complex formation is a spontaneous, endothermic process, and the main driving force for complex formation is entropy. The inclusion complex was confirmed by infrared spectrum (IR).

Abstract: The microstructure and mechanical properties of the low carbon steel plates containing Niobium content of 0.038%, 0.063% and 0.082% with intercritical quenching were studied by SEM, TEM, tensile and impact tests. The results showed that the intercritical quenching steel with high Niobium content can gain the fine microstructure , but also easily obtain the martensite, which made the strength very high but low temperature toughness very low, however, the steel with low Niobium content can not reach enough austenitization level, which caused both low temperature and yield ratio high relatively. So in the given rolling and heat treatment process, there was suitable Niobium content can contribute to obtain the optimal austenization level resulting in the good combination of strength, yield ratio, elongation and low temperature toughness after intercritical quenching in the low carbon steel.

Abstract: In the experiment Al-Zr(CO3)2 components were utilized to in situ synthesize the Al2O3, Al3Zr reinforced aluminum matrix composites. Low frequency and high frequency electromagnetic fields were combined and introduced into the fabrication of particulates reinforced aluminum matrix composites. The average size of particulate and grain size of matrix were refined to 0.5~1μm and 20~40μm separately. The particulates distributed uniformly in matrix. The Lorenz force improved the kinetic condition and accelerated the nucleation of endogenetic particulates. At the meniscus of solidifying billet the high frequency electromagnetic field was applied. The surface quality of billet was enhanced obviously.

Abstract: (Ti,Sn)O2 varistors doped with different amount of La2O3 were obtained by ceramic sintering processing at 1250 . The effect of La2O3 on the microstructure and nonlinear electrical behavior of the (Ti,Sn)O2 ceramics were investigated. The ceramics have nonlinear coefficients of α=6.2–8.5. Experimental evidence shows that small quantities of La2O3 improve the nonlinear properties of the samples significantly. It was found that an optimal doping composition of 1.0mol% La2O3 leads to a low breakdown voltage of 18.1V/mm, a high nonlinear coefficient of 8.5, which is consistent with the highest and narrowest grain boundary barriers of the ceramics.In view of these electrical characteristics, the (Ti,Sn)O2 varistors with 1.0mol% La2O3 ceramic is a viable candidate for low voltage varistor devices. The characteristics of the ceramics can be explained by the effect of the substitution of La3+ for Ti4+ or Sn4+.

Abstract: Impact and abrasion properties of the low carbon alloy steel with different chromium content in acid-ironstone slurry were investigated. The test was carried out by a MLD-10 tester with impact energy of 1.2 J. By analysing the morphology of worn surfaces and the metallographs of the subsurface of the specimen, the impact corrosion and abrasion mechanism was investigated. The results show that the percentage of wear mass loss decreases along with the increment of the Cr content. At the impact energy of 1.2 J, the impact corrosion and abrasion mechanism of low carbon alloy steel with 3% Cr content is the deforming fatigue wear,the mechanism of low carbon alloy steel with 6% Cr content is that shallow spallation due to accumulated deformation for a shorter time and removal of surface material due to multiple plastic deformation for a longer time, multiple plastic deformation belongs to the mechanism of low carbon alloy steel with 9% Cr content.

Abstract: Hydroxyapatite(HAP) nanoparticles were synthesized by a mixed hydroxide method using calcium nitrate tetrahydrate[Ca(NO3)24H2O] and phosphoric pentoxide(P2O5) as raw materials. The synthesized nanoparticles were analyzed by x-ray diffraction (XRD), infrared spectroscopy (IR) and transmission electron microscopy (TEM) methods. The effects of reaction temperature, time and concentration of reactants on the microstructure of the nano-particles have been discussed. The results show that the hydroxyapatite particles synthesized have features of uniform morphology, pure phase and well crystallized nano size. The particle size is in the range of 30-200 nm.

Abstract: The lespedeza stalks with steam pretreatment were fermented to lactic acid by simultaneous saccharification and fermentation (SSF) in this study. Orthogonal design methodology was used to evaluate the optimum SSF conditions that give maximum lactic acid yield. We have investigated the following relative factors, such as temperature, loading of cellulase, calcium carbonate and concentration of substrate. The optimum operating conditions were found to be temperature of 43 °C, cellulase loading of 30 FPU/g substrate, calcium carbonate of 3 % and substrate of 6 %. Comparisons of different steam pretreated conditions on lactic acid yield from lespedeza stalks were also made. The results showed that lactic acid yields from lespedeza stalks with 4 min pretreatment at pressure of 1.0, 1.25, 1.5 and 2.0 Mpa were 41.8 %, 42.5 %, 50.6 % and 64.0 % of the theoretical, respectively. The lactic acid yield from steam pretreated lespedeza stalks was much higher than that of lespedeza stalks without pretreatment (23.9 %). It can be concluded that the lactic acid yield was remarkably improved by steam pretreatment. The yield of lactic acid from steam pretreated lespedeza stalks was 1.68 times higher than that of untreated ones. Additionally, the lactic acid yield could be further promoted from 64.0 % to 89.4 % by washing pretreated stalks with water, which suggested that water processing is a promising method to remove inhibitors in broth to improve lactic acid yield.

Abstract: Based on the research of the tribological properties of the Ni60A/MoS2 composite coating, this paper has studied the forming and self-repairing mechanism of MoS2 lubricating film. The study shows that the forming mechanism includes four stages: the friction beginning stage, MoS2 precipitating stage, MoS2 covering stage and MoS2 forming stage. The destroying processes of the composite lubricating film includes the film thickness decreasing, the crack emerging, the crack expansion, the lubricating film flaking. Meanwhile, the hard particles piercing into the lubricating film also results in the abrasion destroying of the lubricating film and greatly shortening the lifespan of the lubricating film.