Synthesis of Al2O3/TiCN-0.2%Y2O3 Composite by Hot Pressing

Al2O3/TiCN composites were synthesized by hot pressing.The influences of components and HP temperature on mechanical properties,such as bending strength,breaking tenacity and Vickers hardness were investigated.The results showed that the mechanical properties of Al2O3/TiCN composite increased with temperature when hot pressing temperature is below 1650 ℃.The mechanical properties reached their maximums when the composites were sintered at 1650 ℃ for 30 min under hot pressing pressure of 35 MPa,the value of bending strength,breaking tenacity and Vickers hardness was 1015 MPa,6.89 MPa·m1/2,and 20.82 MPa,respectively.When hot pressing temperature was above 1650 ℃,density decreased because of decomposition with increased temperature,and mechanical properties dropped because of rapid growth of grains in size at high temperature.Microstructure analysis showed that the addition of Y2O3 led to the formation of YAG phase so as to inhibit the growth of crystals.This helped to improve breaking tenacity of the composites.TiCN particles with diameters of 1 μm dispersed at Al2O3 grain boundaries,inhibited grain growth and enhanced mechanical properties of the composites.SEM study of the propagation of indentation cracks showed that the bridge linking behavior between matrix and strengthening phase might lead to the formation of the coexisted field of crack deflection,branching and bridge linking.The mechanism of this phenomenon was that the addition of Y2O3 improved the dispersion of TiCN particles so as to enhance the tenacity of the composites.The breaking tenacity was changed from 5.94 to 6.89 MPa·m1/2.     

丙烯酸镧对聚丙烯塑料改性作用的研究

将氧化镧与丙烯酸反应得到的丙烯酸镧与聚丙烯接枝共聚,探讨了丙烯酸镧与聚丙烯接枝共聚的方法和原理,通过电子显微镜对产物进行了定性表征,并用电子拉力试验机、冲击实验机对产物力学性能进行了测定.实验结果表明,经丙烯酸镧接枝共聚后的聚丙烯,拉伸强度随丙烯酸镧引入量的增加有所下降,其冲击强度在接枝共聚后得到了明显的提高.     

Preparation and Mechanical Performance of Rare Earth- Containing Composite Elastomer

Ｌａｎｔｈａｎｉｄｅｃｏｍｐｏｕｎｄｓｂｅｇａｎｔｏｂｅｕｓｅｄａｓｐｌａｓｔｉｃｓｔａｂｉｌｉｚｅｒｉｎｔｈｅ 1 980ｓ[1] .Ｓｉｎｃｅｔｈｅｎ ,ｒａｒｅｅａｒｔｈ (ＲＥ)ｃｏｍｐｏｕｎｄｓｈａｖｅｂｅｅｎｌａｒｇｅｌｙａｐｐｌｉｅｄｉｎＲＥ ｃｏｎｔａｉｎｉｎｇｐｏｌｙｍｅｒｂａｓｅｄｃｏｍｐｏｓｉｔｅ .Ａｎｕｍｂｅｒｏｆｐｌａｓｔｉｃａｎｄｒｕｂｂｅｒｉｔｅｍｓｗｉｔｈｂｅｔｔｅｒｍｅｃｈａｎｉｃａｌｐｒｏｐｅｒｔｉｅｓｗｅｒｅｄｅｖｅｌｏｐｅｄ ,ａｓｗｅｌｌａｓｎｅｗｔｙｐｅｓｏｆｐｏｌｙｍ…     

ER Effect of PMMA Wrapped Alumina-Siloxane Gel Doped with Rare Earths

PMMA wrapped alumina-siloxane gel was obtained by using poly (methyl methacrylate) (PMMA) to wrap alumina-siloxane sol which was made from water glass, aluminum nitrate and a-methacrylic acid. Meanwhile, rare earth ions were used to dope in the course of reaction, and stable suspensions was produced by putting PMMA wrapped microcapsule powder doped with rare earths into methy-silicon oil. It is found that its electrorheologlcal (ER) effect improves strikingly after loading electric field. At a certain concentration, the immediate viscosity increases from 95 to 178 Pa‘s compared to the system without doping.     

氧化物玻璃态结构——络氧离子群

时至今日,对氧化物玻璃态结构尚没有一个完整、确切的理论,本文是继本人对“无机化合物玻璃态结构”的看法之后,提出对无机氧化物玻璃态结构的看法:氧离子和某些中心阳离子以离子——共价混合键形成络氧负离子,络氧负离子以氧为公共顶点相互联结而构成络氧离子群;络氧离子群尚能和很多种络合阳离子形成可变组成、介稳、巨大的络氧化合物,无机氧化物玻璃的化学式为:A_tB_*C_xD_yE_zO_(t/2+ω+3/2x+2y+5/2z)·M~(p+)·N~(q+)。     

玻璃分相

长期以来,人们都认为玻璃是均匀的单相物质。虽然早在二、三十年代就已利用钠硼硅酸盐玻璃的分相来制造高硅氧玻璃,但玻璃分相理论的形成还只是近三十年来的事。着分析技术的发展,超高压透射电镜和X射线小角衍射等方法对玻璃结构的研究,积累了愈来愈多的关于玻璃内部不均匀性的资料。目前已发现在许多玻璃系统中都存在相     

Synthesis and luminescence property of Sr3SiO5:Eu2+ phosphors for white LED

Sr3SiO5:Eu2+ yellow phosphors for white LEDs were synthesized by high temperature solid state reaction method under a reductive atmosphere. The crystalline phases were examined with X-ray diffraction (XRD). Luminescence properties were studied, and effects of various fluxing agents BaCl2, MgF2, CaF2 and BaF2 on the emission spectra were also studied. The optimal Eu2+ concentration and flux were determined. Sr3SiO5: Eu2+ was obtained by firing the sample on optimal composition and fabrication process. The sa...     

玻璃科学技术进展——1986年新德里第14届国际玻璃学术会议

本文扼要介绍了国际玻璃协会组织和第14届国际玻璃学术会议的概况。较全面地论述了玻璃科学、技术和工业的进展,并概括地指出了科研、教学和生产的发展方向。     

稀土发光材料的合成方法

综述了目前国内外稀土发光材料的几种合成方法 ,包括传统的高温固相反应法、几种软化学法 (溶胶-凝胶法、低温燃烧法、水热合成法、缓冲溶液沉淀法 )和物理合成法 (微波辐射合成法 ,CO2 激光加热气相沉积合成法 )。总结了每种合成方法的优缺点 ,并对稀土发光材料新的合成方法进行了展望