Advanced Materials Research Vols. 239-242

Abstract: In order to reduce the emission of volatile organic compounds (VOCs) and save the non-renewable resource, a novel interior wall coating with high bond strength based on metakaolin and modified starch was developed. The process on researches includes three steps. Firstly, cassava starch was reformed including etherification, oxidation, conjugate crosslinking and drying to gain natural polymer glue powder which can be used as forming agent, and a dispensation in producing environment friendly paint for interior wall coating was preliminarily obtained. The dispensation consists of forming agent, calcium carbonate, French chalk, chitosan and mildew preventive. Secondly, the process on metakaolin was studied. Metakaolin shows hydration Characteristics and can make interior wall coating have bond strength and resistance to water. At last, the dispensations and processes in obtaining starch glue, metakaolin and paint powder were decided respectively, and the data in gauging bonding force, resistance to water and the performance of interior wall coating were gained. The research on forming agent was as following: the mixture of cassava starch and NaOH was stirred, and pulverized to be sieved by100 mesh. After reacted stirringly with chloroacetic acid for 1.5h at room temperature, the mixture was oxidized by oxidant for 2h and crosslinked by crosslinking agent for 1h respectively to obtain forming agent. The mass fraction of NaOH, chloroacetic acid, oxidant and crosslinking agent to cassava starch were 6%, 5%, 6% and 0.8%, respectively. The Kaolin selected must contain high percents of Al₂O₃ and SiO₂ , and was calcined at 700°C for 5h to have metakaolin as additive for interior wall coating to improve bond strength and resistance to water. The composition of interior wall coating optimized by orthogonal test is about: 4% of starch glue, 6% of metakaolin, 80% of calcium carbonate, 9.7% of French chalk, 0.1% of chitosan and 0.2% of mildew preventive. The interior wall coating is environmental benign material in building industry.

Abstract: The principle of NC incremental sheet metal forming as well as the process planning, experiment of sphere forming are presented. Because the deformation of sheet metal only occurs around the tool head and the deformed region is subjected to shear deformation and thins, and surface area increases. Sheet metal forming stepwise is to lead to the whole sheet metal deformation. According to sine law, a sphere can’t be formed by NC incremental sheet metal forming process in a single process, rather, it must be formed in multi processes. Thus, the two time path process method is presented to form the sphere, and the experiment is made to verify it. A sphere can be formed from a sheet metal in NC incremental forming process by choosing appropriate tool-path planning. The fracture in the forming component can be avoided by these methods. A sphere of uniform wall-thickness can be formed from the truncated cone by NC incremental forming process.

Abstract: A facile electrochemical approach was developed for controllable synthesis of ytterbium hexacyanoferrate(II) (YbHCF(II)) carambolalike microparticles. The prepared samples were characterized by XRD, EDS and SEM techniques. The composition of YbHCF(II) sample could be assigned to be KYb[Fe(CN)₆]∙xH₂O. By controlling the synthetic conditions, such as applied potential and deposition time, the size and surface morphology of the synthesized materials could be well controlled. The modified Au electrode by YbHCF(II) carambolalike microparticles possesses prominent electrocatalytic activity toward the reduction of hydrogen peroxide.

Abstract: Pure TiO₂, Sm³⁺ and Gd³⁺ co-doping TiO₂ have been prepared by sol-gel method and characterized by the techniques such as XRD and SEM. The photocatalytic degradation of methylene blue (MB) in aqueous solution was used as a probe reaction to evaluate Pure TiO₂, Sm³⁺ and Gd³⁺ co-doping TiO₂ photocatalytic activity. The matrix distortion of TiO₂ increases after co-doping of Sm³⁺ and Gd³⁺ are clearly observed. The results show that co-doping of Sm³⁺ and Gd³⁺ inhibits the phase transformation of TiO₂ from anatase to rutile, decreases the diameter of TiO₂ nano-particles and significantly enhance the photocatalytic activity of TiO₂. When the co-doped amounts for Sm³⁺ and Gd³⁺ are 0.1% and 0.2%, its degradation rate reaches 99%.

Abstract: HA/316L powder asymmetrical functionally gradient biomaterial (FGM) with varying 316L content at 100vol%, 80vol%, 60vol%, 40vol%, 20vol%, 0vol% throughout the thickness of the samples was successfully fabricated by hot pressing(HP) technique. The stress relaxation behavior indicates that gradient structure of the asymmetrical HA/316L FGM has prominent relaxation effect of thermal residual stress. The largest stress in the FGM is 246.13 MPa, which is belonging to tensile stress and at 316L-80vol%HA/ 316L interface. The surfaces of HA/316L FGM are covered with a layer of bone-like apatite after soaking in dynamic SBF, and the apatite increases with the increase of HA content. It reveals that HA/316L FGM with good bioactivity can be obtained with reasonable component design of gradient layers.

Abstract: Solid-state Al−Li/NaBH₄ mixtures with salts have been fabricated for hydrogen evolution through a milling process, providing uniform dispersion of metals Al, Li and salts among pulverized NaBH₄ particles, in order to increase the contacts of NaBH4 with active catalytic sites. The results show that the mixture has good hydrolysis properties, especially that Al−Li−CoCl₂/NaBH₄ mixture has hydrogen yield of 1482 mL g^-1 in 40−minute hydrolysis in pure water, with 100% conversion efficiency. The catalytic effect comes from Al(OH)₃ and Ni₂B or Co₂B, which were fabricated in the hydrolysis process.

Abstract: By using of hot pressing(HP) technique, HA/316L powder asymmetrical functionally gradient biomaterial (FGM) with 316L’s content changing as 100vol%→80vol%→60vol%→40vol%→20vol%→0vol% was prepared successfully. The results show obvious macroscopic gradient changes in the FGM. While the components change continuously in microcosmic, the interfaces among all gradient layers integrate tightly. The addition of 316L powder changes the fracture modes of the composites and improves their mechanical properties. HA contents in HA/316L biological FGM change regularly with different gradient layer, which is responding to the components design. Combining circumstance of phase interface is considerably well and both phase bite into each other at the interface. The two phases of HA and 316L powder dissolve into each other in some degree during hot pressing and the combining mechanism is dissolving behavior.

Abstract: Cu-filled isotropically conductive adhesive/SiO₂ composites were prepared by direct-blending modified SiO₂ into Cu-filled ICAs. The effects of different contents of SiO₂ on the mechanical property were sdudied in this paper. The infrared spectra of the cured product between epoxy resin and imidazole was obtained with FT-IR. The surface morphology of the composite and its fractured surface after tensil test were observed by scanning electron microscope(SEM). In addition, energy dispersive spectrometry(EDS) was applied to analyze the distribution of Si in the adhesive layer. Experimental results showed that a small amount of SiO₂ powders could evenly distribute in the Cu-filled ICAs, and as a reslut the mechanical property of Cu-filled ICA/SiO₂ increased dramatically with the addition of SiO₂. The best shear strength of the composite could reach up to 16.1MPa and 36.4% higher than the ICAs without addition SiO₂ when the content of SiO₂ was 3%.

Abstract: Ni/TiC composites have been produced using laser induced self-propagating high-temperature synthesis. The chemical composition and microstructure were investigated by means of X-ray diffraction and scanning electron microscope. The sintered density and mechanical properties such as bending strength and micro-hardness were also measured. The results showed that the synthesized products were consisted of TiC and Ni phases, which indicated that the TiC was synthesized by the in-situ reaction. Moreover, the results revealed that the sintered density increased and the micro-hardness and bending strength of the synthesized products gradually decreased with the increasing of Ni contents.

Abstract: The ablation properties of C/C-ZrC-SiC composites prepared by precursor infiltration and pyrolysis processes were studied by the H₂-O₂ ablation method. The results indicate that the ablation rate of C/C-ZrC-SiC composites decreases with increasing density of the composites. The linear ablation rate and mass ablation rate of the C/C-ZrC-SiC composites (ρ=1.69g·cm^-3) were 0.00211mm·s^-1 and 0.5179mg·s^-1, only 20.6% and 31.6% of those of C/C composites (ρ=1.78g·cm^-3) respectively. The introduction of ZrC-SiC into the matrix greatly enhanced the anti-oxidative and ablation property of the C/C composite. The ablation mechanisms of the C/C-ZrC-SiC composites were supposed to be the synergistic effects of thermo-chemistry ablation (oxidation and sublimation) and mechanical erosion.