Advanced Materials Research Vols. 239-242

Abstract: In situ reaction synthesized TiB reinforced titanium matrix composites were fabricated using rapid non-equilibrium synthesis techniques of laser cladding. Titanium matrix composite were laser cladding treated on Ti-6Al-4V using Ti and B powder mixture, and the designed weight fractions of B were 10 wt.% in the starting powder mixture. The composite coating mainly consists of α-Ti and TiB. The reinforcement TiB is dispersed homogeneously in the composite coating with pre-placed powder thickness of 0.5mm. The influence of pre-placed powder thickness on microstructure of laser cladding coatings was discussed.

Abstract: In situ prepared zinc disorbate (ZDS) in natural rubber (NR) by the reaction of zinc oxide and sorbic acid was used to reinforce the dicumyl peroxide-cured NR vulcanizate. The changes in mechanical properties of NR vulcanizates after ageing and were determined and the structures and thermal stability of vulcanizates were also analyzed using scanning electron microscope and thermal gravimetric analyzer. The change ratios in tensile strength and elongation at break of NR vulcanizate with theoretic formation of ZDS of 21phr can be increased to -33 from -44 and -27 from -38 after ageing and the initial weight loss temperature of NR vulcanizate can be increased for about 7°C as compared to un-reinforced NR vulcanizate, indicating that the antioxidative behavior and thermal stability of NR can be improved significantly with theoretic formation of ZDS of 21phr.

Abstract: A novel thermoplastic elastomer was applied in the measurement of extravehicular liquid cooling garment and the satisfying result in improving the heat dissipating capacity of liquid cooling garment was achieved. Firstly, five kinds of elastomer were selected, which were ethylene-vinyl acetate copolymer (EVA), high temperature vulcanized silicone rubber (HTV), medical used silicon rubber (MSR), natural rubber latex (NRL) and thermoplastic SBS complex (TPR). To evaluate the synthetic performance of these materials, a series of experiments characterizing material’s mechanical and thermodynamic properties was performed, including tensile and compression test, heat property test and so on. Meanwhile, fuzzy mathematic method was employed to get parameters’ weight distribution, and then fuzzy decision-making method was adopted to perform synthetic evaluation, which showed that TPR had satisfying optimization performance and can be used as simulated skin in thermal manikin. Finally, to verify the function of TPR simulated skin, comparative experiments were performed in climate chamber when thermal manikin covered with TPR simulated skin and did not cover with TPR simulated skin. Results show that TPR simulated skin can effectively improve the heat dissipating capacity of liquid cooling garment.

Abstract: A series of experiments was performed on studying the dynamic heat and moisture transferring procedure and evaluating heat-moisture comfort properties of functional moisture transported and dry-fast fiber in wearing conditions that produce continued sweat. Experiments were performed in two different environmental conditions, which were the most comfortable condition and an extremely uncomfortable condition for humans. The real time changes of temperature and relative humidity in inner and outer surfaces of different fiber fabrics were measured using self-made textile-microclimate measuring instrument. Then, fabric’s comprehensive heat-moisture comfort properties were obtained. Results show that fine denier polypropylene fiber as a newly moisture transported and dry-fast functional fiber has better heat-moisture comfort properties than other conventional fibers, and it is more suitable for sportswear fabric.

Abstract: In order to change the dendritic grain structure of Al-Cu alloy to equaxed grain, the effects of electromagnetic stirring on the microstructure of an Al-Cu alloy were investigated. The results show that the positive and negative stirring has the best stirring effects at the same condition. It is apparent that the morphology of α-Al is closely related with the comprehensive interactions between stirring strength and stirring time.

Abstract: An ECMP slurry screening protocol is proposed based on inhibition efficiency of inhibitor in copper static corrosion test, aiming at enhancing the planarization efficiency of copper ECMP slurries. The elctrochemical properties of copper in electrolytes including H₃PO₄ and BTA with different concentrations are studied basing on Linear Sweep Voltammetry (LSV) and chronoamperometry under static corrosion states. According to analysis of the anodic current, material removal rate (MRR) and inhibition efficiency of BTA, an electrolyte formula of 30 wt% H₃PO₄+0.01M BTA is sort out and the anodic potential on copper should be set below 0.5 V.

Abstract: Conducting polymers poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-ethylenedithiathiophene) (PEDTT) have been synthesized by solid-state polymerization of 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) and 2,5-dibromo-3,4-ethylenedithiathiophene (DBEDTT) respectively in air and under vacuum. Both polymers were completely insoluble in common organic solvents and retained partial crystal structure of monomers as indicated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. Thermoelectric tests showed that PEDTT exhibited Seebeck coefficient about 120 µV K⁻¹ at 170 K, which is higher than PEDOT, while the later exhibited higher electrical conductivity (0.1S cm^-1 at 298 K) and better thermal stability indicated by the thermal analyses. These results showed that replacement of oxygen by sulfur in the monomer structure played an important role on the properties of polymers.

Abstract: Based on cellular automata, a model of simulating grain growth is established to study the effects of the second phase particle’s size distribution on grain growth. The simulation results show that the second phase particles in the matix pin the grain boundary and then inhibit the grain growth. Different size distributions of the second phase particles have different pinning effect on the grain boundary, and the relationship of average grain size for the material with the second phase particles is R_Lognormal＞R_Uniform＞R_Normal. The correlative laws obtained from the simulation is in accordance with the theoretical models.

Abstract: We report a label-free, fast, fluorescence turn on assay for Hg²⁺ detecton by using mercury-specific DNA (MSD), Sybr Green I (SG) and gold nanoparticles (AuNPs). SG efficiently discriminates MSD and MSD/Hg²⁺ complex. The addition of gold nanoparticle decreases the background fluorescence signal further for MSD. The fluorescence intensity of MSD/Hg²⁺ complex keeps constant after addition of AuNPs. This property improves the signal-to-background ratio and decreases the detection limitation further. In addition, the method shows improved selectivity compared with that in the absence of AuNPs. This strategy could be applied to the detection of potassium ions and showed good generality.

Abstract: The principle of NC incremental sheet metal forming process as well as the experiment of cone forming are presented. Because the deformation of sheet metal only occurs around the tool head and the deformed region is subjected to stretch deformation, the deformed region of sheet metal thins, and surface area increases. Sheet metal forming stepwise is to lead to the whole sheet metal deformation. The experiment results show that in the case of the parallel line type tool path, a uniform thickness of the deformed region is maintained and in good accordance with that obtained by the sine law. It is found that success in the forming depends on the forming half-apex angleθof the truncated cone. It can be obtained that NC incremental sheet metal forming process is a plane deform process and conforms to the sine law, i.e.t=t₀ sinQ.