Advanced Materials Research Vols. 430-432

Abstract: The cosine solution of the Fick-2 Law, which was considered as the mathematical model of homogenization of dendritic segregation, has always been used to analyze high temperature diffusion. Cosine solution can not exactly describe the actual distribution of alloying elements in dendrite, as the slope of cosine curve is quite gentle. Based on segregation ratio SR, a new mathematical model was established by using Gauss solution of the Fick-2 Law. The new model could describe the evolution of homogenization of alloying elements during the process of high temperature, which was proved by some specific examples.

Abstract: As basis of the big diameter crystal development, the single crystal automatic growth is the most important technique for system standardization and mass production. In this article, author introduced a new useful way for the single crystal automatic growth of float zone. By setting the growth interval and controlling parameter, PLC controller could automatically control the single crystal growth when the single crystal’s diameter is greater than 50mm. This method applied to the machine system can greatly reduce the fault of manual operation as well as labor intensity. Also it improved the single crystal quality which increases the ability to develop big diameter single crystal in the future.

Abstract: Alloy steel 9SiCr is quenched by a certain proportion of mixture gas of nitrogen and spray water at atmosphere, and the continual cooling curve during quenching is determined, the rigidity of quenched workpiece is measured and the metallographic map is captured. The results show that it can improve the cooling effect of quenching medium on the one hand; on the other hand, it can decrease the deformation and residual stress of workpieces. The results show that the rigidity of quenched workpiece is about 62 (HRC), which is corresponding with the rigidity after oil quenching. Martensite phase transformation occurs at the end of quenching that can be seen from the metallographic map.

Abstract: New bulk nanostructure-dendrite Ti₄₄Cu₄₆Co₄Zr₆ composite with excellent mechanical properties has been fabricated by using copper molder casting through systematic alloy design from binary Ti₅₀Cu₅₀. The results showed that the micro-scaled β-Ti (M) solid solution embedding on the nanostructured matrix, which resulted in the excellent mechanical properties: high fracture strength (σ_f=2278 MPa) and good ductility (ε_p=9.01%) under quasi-static compression.

Abstract: To protect carbon/carbon (C/C) composite against oxidation, a SiC/Si/MoSi₂ anti-oxidation coating was preparated on C/C composite by embedding with the powder mixture of Si, C and MoSi₂ at 1600°C in argon atmosphere. In order to investigate the effection of SiC whisker on formation and oxidation resistance of coating, SiC whisker was introduced to coatings by pyrolysis of hydrogen silicone oil (H-PSO) at 1600°C before embedding treatment. Oxidation experiment was carried out in the static air at 1400°C for 2h, and thermal cycling between 1400°C and room temperature for 5 times. Morphology and phase structure of the coating were analyzed by XRD and SEM with EDS. The anti-oxidative mechanism of coating was investigated by comparing the diversity of morphology and phase structure before and after oxidation. The research indicates that the introduction of SiC whiskers improves the performance of the coating effectively. It can effectively decrease the cracking of the coating in the oxidation process, and avoid the excessive penetration of silicon to protect the matrix from being excessively corrosion.

Abstract: The carbon fiber (CF) reinforced pantograph sliding plates were fabricated by hot pressing with modified phenolic resin as bonder, and the continuous carbon fiber, copper and graphite respectively were reinforcing phase, electric conductive phase and lubricating phase, respectively. The impact toughness, electric resistance and wear resistance of the slide plate were tested. The structural characteristics of the pantograph sliding plates were investigated by scanning electron microscopy (SEM). The results show that the addition of CF mass fraction can increase impact strength and density; while resistivity has a lower trend; the volume abrasion loss and friction coefficient are decreased then increased dramatically. The fiber and resin interface adhesion is good for specimen impact cross section smooth. In addition, adhesive wear and abrasive wear are the main wear form of pantograph slide plates.

Abstract: Based on the study of the mechanics features of pneumatic artificial muscle including the nonlinearities in material, geometry, and with the method of nonlinear finite element analysis, the three-dimensional finite element model of a pneumatic artificial muscle was established. The analytical results were confirmed by the experiment with the use of a pneumatic artificial muscle test bench.

Abstract: as the gear tooth wideth is very wide, involute gear drum mixer would have a great impaction and vibration to the entire system when the involute gear meshed in and out.we propose a new type of drum mixer which is pin gear drum mixer and we analysised the dynamics of pin gear drum mixer and involute gear drum mixer.

Abstract: Raman spectra of the magnetic geometric frustration material – the botallackite-structure α-Cu2(OH)3Cl polycrystalline sample were measured down to liquid N2 temperature. It is found that the hydroxyl stretching bands shift abnormally according to the lattice thermal expansion effect of normal materials, i.e., they redshift with decreasing the sample temperature (negative thermal expansion) using liquid N2 cooling while other bands blueshift. This abnormality was also confirmed by observing the band-shifting caused by local laser heating effect using different laser powers, and can be qualitatively explained by checking the local hydroxyl environment with a trimeric hydrogen bond.

Abstract: The optimal conditions of by the culture of Bacillus sp.were examined, using beer wastewater to replace glucose as carbon source and energy source in the culture medium. Results showed that the COD concentration in beer wastewater favorable for the growth of the Bacillus sp.was 5000 mg•L^-1, and inoculum size of 5%(v/v), 30^◦C, initial pH 7.0 and shaking speed of 150 r•min^-1, under the optimal culture conditions, the Bacillus sp. biomass was effective in flocculating some soluble reactive dyes in aqueous solution, reactive Light-Yellow K-4G and reactive Turquoise Blue KN-G with a decolorization efficiency of 93.8 and 95.5%, respectively, using 20 mL of the culture medium in 500 mL of 100 mg•L^-1 dye solution.