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排序方式: 共有3853条查询结果,搜索用时 31 毫秒
31.
《Inorganic chemistry communications》2007,10(10):1181-1184
Two novel 3d–4f polymers [La(H2O)4][M2TTHA(SCN)2] · H3O+ (M = Ni(1), Cu(2), H6 TTHA = triethylenetetraaminehexaacetic acid) were synthesized and characterized by X-ray single-crystal diffraction, elemental analysis, IR and magnetic properties. Two complexes show 3D framework, comprising an unusual infinite 1D chain based on heterometallic La2M2 rings (M = Ni(1), Cu(2)). 相似文献
32.
《Reactive and Functional Polymers》2007,67(11):1218-1224
A series of organic–inorganic hybrid consisting of polyimide (PI) prepared from pyromellitic dianhydride (PMDA) and 4,4′-oxydianiline (ODA), organically modified montmorillonite (OMMT) and polydimethylsiloxane (PDMS) were successfully prepared by in situ sol–gel process. OMMT was prepared by surface treatment of montmorillonite (MMT) with hexadecyltrimethylammonium bromide. X-ray diffraction (XRD) analysis showed that the OMMT layers were exfoliated into the polymer matrix at 2% of OMMT content. The PI–OMMT–PDMS hybrids at 2% of OMMT content were transparent when PDMS content was less than 5%. The PI–OMMT–PDMS hybrid showed better tensile modulus, strength and elongation at break than that of pristine PI due to the reinforcement effect of OMMT and toughening effect of PDMS. The thermal stability of hybrids such as the decomposition temperature and weight residue at 800 °C also increased with the increase of PDMS content as evidenced by thermogravimetric analysis (TGA). 相似文献
33.
《Journal of the European Ceramic Society》2006,26(9):1701-1706
In present study, dense CaSiO3 (CS) ceramics have been fabricated through spark plasma sintering (SPS) technique using β-CS powder prepared by chemical precipitation method. The β-CS ceramic sintered at 950 °C has a relative density of about 95% and shows a fine microstructure with an average grain size of 0.6 μm, thus expresses good bending strength of about 294 MPa. The simulated body fluid (SBF) immersion tests show that the dense β-CS ceramic has a high hydroxyapatite (HAp) formation rate on its surface. The HAp layer formed on the CS ceramic surface has a granular structure consisting of silkworm-like HAp grains, and the thickness of HAp and Si-rich layer are 70 and 120 μm, respectively. 相似文献
34.
Akhtar Farid GUO Shi-ju 《中国有色金属学会会刊》2006,16(3):629-632
Pressureless infiltration process to synthesize Si3N4/Al composite was investigated. Al-2%Mg alloy was infiltrated into Si3N4 and Si3N4 containing 10% Al2O3 preforms in the atmosphere of nitrogen. It is possible to infiltrate Al-2%Mg alloy in Si3N4 and Si3N4 containing 10% Al2O3 preforms. The growth of the dense composite of useful thickness was facilitated by the presence of magnesium powder at the interface and by flowing nitrogen. During infiltration Si3N4 reacted with aluminium to form Si and AIN, the growth of composite was found to proceed in two ways, depending on the Al2O3 content in the initial preform. Firstly, preform without Al2O3 content gives rise to AIN, Al3.27Si0.47 and Al type phases after infiltration. Secondly, perform with 10% Al2O3 content gives rise to AIN-Al2O3 solid solution phase (AION), MgAl2O4, Al and Si type phases. AlON phase was only present in composite, containing 10% Al2O3 in the Si3N4 preforms before infiltration. 相似文献
35.
A technique based on viscous polymer processing (VPP) was described, which can produce high ceramic content green fibers. PZT-5 ceramic powders were ball milled to get high dispersibility. The slurry prepared for VPP was a composition of PZT-5 powder, PVA binder and glycerin. High ceramic content PZT-5 fibers were extruded with the slurry. The results show that the ceramic powders have fine mean particle size of 0.54 pan, high specific surface area of 3.55 m^2/g and zeta potential of 8.81 mV after 16 h milling. The fibers sintered at 1 280 ℃ for 4 h have pure perovskite structure and grains of 2-5 μm in size, with little pores or cracks. The ultimate tensile strength of sintered fibers is up to 13.84 MPa compared with 2.88 MPa of green fibers. The remnant polarization (Pr) and coercive field (Ec) of the fibers are 50.65 μC/cm^2 and 2.45 kV/mm, respectively. This fiber can withstand an electric field of 9 kV/mm higher than the ceramic (5 kV/mm), which shows high directional and compact qualities. 相似文献
36.
《Synthetic Metals》2006,156(18-20):1187-1193
Miscible blend of conductive polyaniline/polyurethane (PANI/PU) showed preferable electrical property at low percolation threshold compared to immiscible blend of PANI/polystyrene-isoprene-copolymer (PANI/SIS) and carbon black/PU composite (CB/PU). The time dependence of the electrical conductivity was investigated with these samples aged under different humidity and temperatures. The electrical conductivity of PANI/PU (11.5/88.5, v/v) decreased with aging time and the morphology changed with time in the coexistence of high moisture and high temperature. After the aging treatment, the film of the miscible blend was re-dissolved and re-cast. The morphology and electrical conductivity were found to recover to the same state as the original film. In addition, the recovery mechanism of the morphology and the conductivity was also proposed here. 相似文献
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