Advanced Materials Research Vols. 295-297

Abstract: Taking ultraprecision grinding of silicon nitride ceramic as an example, this paper mostly introduces some influences of diamond wheel’s specialties on the grinding process and surface quality during ELID (electrolytic in-process dressing) grinding of hard and brittle materials. Research indicates that grain size and concentration of abrasive material should be reasonably selected based on the surface roughness. And Inhomogeneity of concentration distribution along wheel circumference will result in heterogeneity of insulator layer state, which will bring difference in the number of abrasive grain in the grinding area, thereby changing the actual cutting depth of every abrasive grain. Dynamic balancing of grinding wheel should be accurately adopted to reduce eccentric mass, furtherly to avoid generating waveness on the workpiece surface. For the purpose of reflecting rightly compositive effect from eccentricity of wheel shape, roundness of the wheel and periodical vibration derived from eccentric mass, actual radial runout of grinding wheel should be well and truly measured and controlled based on the wheel’s surface profile during wheel is rotating at working speed.

Abstract: Soft-contact electromagnetic continuous casting is one of innovative technologies for the development of steel industry. In this paper, the present situation was reviewed from five aspects: the soft-contact mold material and structure parameter design, the electromagnetic field distribution, the meniscus shape and movement behavior, casting slab surface quality improvement mechanism and the method of magnetic fields imposed. The main questions of the technology were analysed, and the remarhable in the process of industrialization were pointed out.

Abstract: The multihollow and elastomeric beads from polyurethane acrylate (PUA), ethyl methacrylate (EMA) and styrene (St) are prepared by suspension polymerization using n-heptane as porogen and 1,2-divinylbenzene (DVB) as crosslinking agent. The SEM results show that the beads of PUA-EMA-St crosslinked copolymers have many and large hollows on their surfaces and interiors, and the hollow sizes are dependence of the copolymer composition and the dosages of porogen. Average hollow diameters decrease as the dosages of the contents of PUA and porogen decrease.

Abstract: Hemicellulose isolated from DmM was converted to novel functional biopolymers by maleylation using maleic anhydride as reactant and LiOH as catalyst. The reaction was performed under various temperatures, times, and the amounts of catalyst and maleic anhydride on the degree substitution (DS) of products were discussed. Comparison of the reaction in different media was discussed in detail. The product had the maximum degree of substitution (DS) of 0.75. Novel functional polymers containing with carbon-carbon double bond and carboxyl groups could be confirmed by ¹³C NMR spectroscopy. The behavior of novel hemicellulosic derivatives was monitored by means of thermogravimetry (TG) and differential thermal analysis (DTA). It was found that the products with a high DS had a lower thermal stability than the native hemicelluloses.

Abstract: Composites of copper–tin (Cu_xSn_1-x) nanoclusters were synthesized using the magnetron dc sputtering gas–condensation technique. Targets with controlled ratios of Sn to Cu were used to produce Cu_xSn_1-x with different compositions. The effects on the nanocluster size and yield of the sputtering discharge power, inert gas flow rate, and aggregation length were investigated using a quadrupole mass filter. The sputtering discharge power was optimized to maximize the nanocluster yield. The results show that as the inert gas flow rate increases the nanocluster size increases and then decreases. These dependences could be understood in terms of the dominant nanocluster production mechanisms. This work demonstrates the ability of controlling the Cu_xSn_1-x nanoclusters’ size and composition by optimizing the source operation conditions.

Abstract: A new photochromic compound 1-(2-ethyl-3-benzothienyl)-2- (2-n-hexyl-5-formyl-3-thienyl) perfluorocyclopentene (1a) was synthesized, its photochromic properties were examined, the result indicated that the color of the compound 1a changed from colorless to a blue one upon irradiation with 297 nm UV light, a new absorption maxima were observed at 583 and 594 nm in hexane and PMMA film, respectively. The new photochromic compound also exhibited remarkable holographic optical recording character.

Abstract: Based on the research for the structure of the ceramic nanocomposites’ intragranular for Al₂O₃/ZrO_2(n)，we did the test by the workpiece two-dimensional vibration grinding(WTDUVG), and focus on analyzing the characteristic and the effect element of the two-dimensional ultrasonic vibration grinding ceramic surface residual stress by the XRD diffraction. The result show that ceramic dimensional ultrasonic vibration grinding surface tensile stress is less than the same conventional grinding (CG) surface under tensile stress; two-dimensional ultrasonic vibration grinding surface residual compressive stress than conventional ground surface residual stress under the same grinding. Material removal mechanism of the grinding nature of the surface residual stress, when the material removaled by ductile deformation, grinding surface equal residual stress; when the material removaled by brittle- ductile mixed mode, the grinding surface tensile stress reduced, because the fracture of the ground surface, tensile stress released. As a results, the grit size of grinding wheel, Grinding depth and workpiece mechanical properties are the main technology factors affected the nature and size of the residual stress of ground surface.

Abstract: A new mechanism for latex migration during coating consolidation was proposed, which suggested that Brownian motion induced particle diffusion, as described by the classic Stokes-Einistein Equation for dilute suspensions, was the main force driving latex particles to migrate to the coating surface. Series of latex clay coating colors were prepared and apllied on impervious substrate. By measuring carbon content at coating surface dried under different conditions, the new mechanism was validated.

Abstract: The inherent odor of teak wood has repellent, and has an obvious effects on animals and human. In this work, the weight loss of volatile substances of different provenances teak including India, Nigeria and Thailand has been studied by TGA. The emmision of volatile substances starts at 30°C and ends at 100°C, lossing weight of the all samples are very less in the range of 100-200°C. When the temperature is in the range of 200-250°C, the hemi-cellulose and cellulose is pyrolyzed and the char starts to form. The results all the curves of TGA for the teak samples is similar, the sapwood losing weight is clearly higher than the heartwood for the same provenance teak. The volatile substances of sapwood are ranked as follows:V₃₀₇₁> V₃₀₇₀> V₃₀₇₂> V₈₀₂₄> V₃₀₇₄> V₁₀₀₉> V₃₀₇₈> V₁₀₀₇, and the heartwood: V₃₀₇₄> V₃₀₇₀> V₁₀₀₉> V₈₀₂₄> V₃₀₇₂> V₃₀₇₁> V₃₀₇₈> V₁₀₀₇.

Abstract: In order to transform the diamagnetism of expanded graphite (EG) to ferrimagnetism and improve its electromagnetic interferential capability, nano γ-Fe₂O₃/EG magnetic composite materials was prepared by sol-gel and low temperature self-combustion technique. The as prepared samples were characterized by SEM, XRD and Magnetic hysteresis cycle test. The results indicated that the composite materials had ferrimagnetism property after the embedding of γ-Fe₂O₃, but the average conductivity of the composites decreases gradually with the increase of γ-Fe₂O₃. Different mixing ratio of ferrite gel and graphite intercalation compounds produced ferric oxide with different crystal form and shape. When the content of ferrite sol was low, spherical γ-Fe₂O₃ with the mean size of 31.69nm was formed, and spread unevenly on the surface and interformational micelles of EG. High content of ferrite sol (83wt%) produced more perfect crystal γ-Fe₂O₃ of pentahedron shape with the mean size of 44.68nm, and a few of α-Fe₂O₃ occurred which lead to the decline of the magnetic property of the composite materials.