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包覆型ZrO2(3Y)粉体研制 总被引:13,自引:3,他引:10
用微波法制备单分散、纳米水合二氧化锆,利用异相成核工艺在水合二氧化锆粒子表面均匀包覆一层Y(OH)3,制备出包覆型ZrO2(3Y)粉体先驱体.最后对煅烧ZrO2(3Y)粉体进行相结构分析,发现在室温下包覆型ZrO2(3Y)粉体中无m-ZrO2存在.结果表明;利用包覆的方法能将Y2O3均匀地加入到ZrO2中,提高ZrO2(3Y)粉体中亚稳定t-ZrO2的含量. 相似文献
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聚合物分散剂对纳米TiO_2水悬浮液分散稳定性的影响 总被引:9,自引:0,他引:9
纳米TiO2复合乳胶漆的制备一般要求预先分散纳米TiO2并制成水悬浮液。为了制备稳定分散的纳米TiO2水悬浮液,研究了乳胶漆中常用的分散剂SN5040和PEG对纳米TiO2在水溶液中分散稳定性的影响,并分析了分散剂的作用机理。实验结果表明:SN5040能有效分散纳米TiO2,按照先SN5040后PEG的方式添加一定比例的混合分散剂,PEG能在SN5040吸附层上嵌入式吸附,显著提高了纳米TiO2的Zeta电位值,更有利于纳米TiO2水悬浮液的分散稳定性。红外光谱分析(FT-IR)表明:SN5040主要是通过与表面裸露的Ti4+形成配位键而吸附到纳米TiO2粒子表面上的。 相似文献
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本文通过在纳米SiC颗粒表面包覆一层Al2O3,使包覆型SiC与Al2O3具有相似的表面化学性质,从而包覆型SiC-Al2O3混合粉悬浮液具有相似于单相Al2O3悬浮液的流变性质。研究了分散剂、颗粒匹配及温度对包覆型SiC-Al2O3混合粉悬浮液流变性质的影响。结果表明,对于亚微米粉,尤其纳米粉,高聚物电解质分散剂不能改善其流变性;合适的颗粒匹配及温度可以改善悬浮液的流动性。,The surface chemical property of SiC was similar to that of Al2O3 by coating SiC with Al2O3,so that the rheological behavior of coated SiC-Al2O3 suspension was like to that of single phase Al2O3 suspension.The effect of dispersant,size distribution and temperature on rheological behavior of coated SiC-Al2O3 suspension were studied.Results indicated that polyelectrolyte did not improve rheological behavior for fine powder suspension,especially for nanosized powder suspension,but proper size distribution and temperature could. 相似文献
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K. A. Gillis 《International Journal of Thermophysics》1997,18(1):73-135
Measurements of the speed of sound in seven halogenated hydrocarbons are presented. The compounds in this study are 1-chloro-1,2,2,2-tetrafluoroethane
(CHClFCF3 or HCFC-124), pentafluoroethane (CHF2 CF3 or HFC-125), 1,1,1-trifluoroethane (CF3CH3 or HFC-143a), 1,1-difluoroethane (CHF2CH3 or HFC-152a), 1,1,1,2,3,3-hexafluoropropane (CF3CHFCHF2 or HFC-236ea), 1,1,1,3,3,3-hexafluoropropane (CF3CH2CF3 or HFC-236fa), and 1,1,2,2,3-pentafluoropropane (CHF2CF2CH2F or HFC-245ca). The measurements were performed with a cylindrical resonator at temperatures between 240 and 400 K and at
pressures up to 1.0 MPa. Ideal-gas heat capacities and acoustic virial coefficients were directly deduced from the data. The
ideal-gas heat capacity of HFC-125 from this work differs from spectroscopic calculations by less than 0.2% over the measurement
range. The coefficients for virial equations of state were obtained from the acoustic data and hard-core square-well intermolecular
potentials. Gas densities that were calculated from the virial equations of state for HCFC-124 and HFC-125 differ from independent
density measurements by at most 0.15%, for the ranges of temperature and pressure over which both acoustic and Burnett data
exist. The uncertainties in the derived properties for the other five compounds are comparable to those for HCFC-124 and HFC-125. 相似文献
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Weiwei Zhu Jichun Chen Chuanyong Hao Jinsong Zhang 《材料科学技术学报》2014,30(9):944-948
ZnO-Al2O3-B2O3-SiO2 (ZABS) glass powder was used as interlayer to join alumina ceramics. The effect of joining temperature on the microstructure and strength of joints was investigated. The results showed that the ZABS glass can react with alumina substrate to form a layer of ZnAl2O4 at Al2O3/glass interface. Bending test exhibited that low joining temperature (1150℃) led to low joint strength due to the formation of pores in the interlayer, originated by high viscosity of the glass. High joining temperature (1250 ℃) also resulted in low joint strength, because of large CTE (coefficient of thermal expansion) mismatch between amorphous interlayer and alumina substrate. Therefore, only when the joining temperature was appropriate (1200℃), defect-free interface and high joint strength can be obtained. The optimum joint strength reached 285 MPa, which was the same as the base material strength. 相似文献
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Calculation of the Quasiternary Systems:Si_3N_4-Y_2O_3-SiO_2,Y_2O_3-SiO_2-BeO and Y_2O_3-Al_2O_3-BeO
Based on the thermodynamic model of Kaufman for the calculation of quasibinary and quasiternary system, numerical method for the calculation of stable equilibrium is developed and thermodynamic data of undefined phases are discussed in this work for several ceramic systems.The calculated isothermal sections in Si3N4-Y2O3-SiO2 system meet well with other previous calculated phase diagrams and experimental results. The diagrams in Y2O3-SiO2-BeO and Y2O3-Al2O3-BeO systems are calculated for the approach of prediction. 相似文献
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A microstructural study has been carried out of plasma-sprayed Al2O3 and mixed and sintered Al2O3Y2O3. In order to ascertain the degree of metastability achieved by plasma spraying, these results are compared with a similar experiment utilizing a CO2 laser for melting and the hammer-and-anvil technique for quenching of the same materials. X-ray diffraction methods were used to determine the obtained phases and crystal structures. In addition, transmission electron microscopy was used to confirm the phases present and to study their morpology. The porosity was studied with both mercury intrusion porosimetry and small angle neutron scattering. The addition of Y2O3 is shown to decrease the porosity from 15% to 7.5%. Adhesion is likewise related to the addition of Y2O3 and it is seen that adhesion of the mixture is measurably improved over that of pure Al2O3. The implication of these results is discussed. 相似文献
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本文给出了 Si_2N_2O-Al_2O_3-La_2O_3和 Si_2N_2O-Al_2O_3-CaO 系统的亚固相图。实验结果表明:在 Si_2N_2O-Al_2O_3-CaO 系统中有一个未知结构的新化合物 CaO·Si_2N_2O,在3CaO·Si_2N_2O 和3CaO·Al_2O_3两化合物之间形成连续立方固溶体。而 Si_2N_2O-Al_2O_3-La_2O_3系统中则没有发现新化合物。在两个系统的富 Si_2N_2O区,过量的 Si_2N_2O 与 La_2O_3和 CaO 分别反应形成 Si_3N_4与 La_(10)[SiO_4]_(?)N_2(H-相)(和 CaSiO_3。所研究的这两个三元系统中,分别形成了如下几个四元相容性区。在 Si_2N_2O-Al_2O_3-La_2O_3系统内有:H-Si_3N_4-La_2O_3·Si_2N_2O-La_2O_3·Al_2O_3;H-Si_3N_4-La_2O_3·Al_2O_3-La_2O_3·11 Al_2O_3;H-Si_3N_4-La_2O_3·11 Al_2O_3-Al_2O_3;H-Si_3N_4-Al_2O_3-O′s.s;H-Si_3N_4-O′s.s-Si_2N_2O在 Si_2N_2O-Al_2O_3-CaO 系统内有:Si_3N_4-CaSiO_3-CaO·Si_2N_2O-3CaO·Al_2O_3;Si_3N_3-CaSiO_3-3CaO·Al_2O_3-2CaO·Al_2O_3·SiO_(?);Si_(?)N_(?)-CaSiO_3-2CaO·Al_2O_3·SiO_2-Al_2O_3;Si_3N_4-CaSiO_3-Al_2O_(?)-O′s.s;Si_3N_4-CaSiO_3-O′s.s-Si_(?)N_(?)O 相似文献
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In the temperature range 1600 to 1900° C, the system A2O3-Cr2O3-ZrO2 is characterized by the coexistence of ZrO2 (unstablilized) and an (Al, Cr)2O3 solid solution series. In the systems MgO-Cr2O3-ZrO2 and MgO-Al2O3-ZrO2 a nearly stoichiometric spinel coexists with both stabilized and unstabilized ZrO2. At temperatures above 1600°C a new ternary Mg-Al-Zr oxide becomes stable in the MgO-rich part of the MgO-Al2O3-ZrO2 system. 相似文献