硬脂酸法制备TiO2-SnO2纳米粉

采用硬脂酸法分别制备了SnO2纳米粉体及TiO2-SnO2混合纳米粉,并应用XRD和TEM等分析方法对所得粉体进行了表征.结果显示,采用硬脂酸法制备了粒径约18nm的SnO2纳米粉体和粒径约5-15nm的TiO2-SnO2纳米粉体.     

Si_2N_2O-Al_2O_3-La_2O_3和Si_2N_2O-Al_2O_3-CaO系统的亚固相关系

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     

Ti(acac)2Cl2/AlEt2Cl(或AlEt2Cl-ZnCl2)催化剂催化丙烯腈聚合反应

研究了Ti(acac)2Cl2／AlEt2Cl催化丙烯腈聚合反应,分析了加入第三组分ZnCl2对聚合反应的影响,用^13C—NMR对聚合产物进行了表征,并探讨了聚合反应机理。结果表明,随着聚合温度的提高和聚合反应时间的增加,单体转化率增大,聚丙烯腈的分子量提高。当体系中n(AN)／n(Cat)超过一定量时,则得不到高聚物。体系中加入ZnCl2能明显提高单体转化率和产物分子量,并且产物的三单元规整结构含量明显增加。     

Ti/SnO_2 Sb_2O_3 MnO_2/PbO_2阳极的性能研究

制备了一种非贵金属阳极－Ｔｉ／ＳｎＯ２＋Ｓｂ２Ｏ３＋ＭｎＯ２／ＰｂＯ２,并用ＸＲＤ、ＳＥＭ进行了表征,计算出了电极的分形维数,测定了该电极在硫酸中的使用寿命和动力学参数,把该电极用于处理含酚废水和Ｐｂ电极进行对比．结果表明,节电３３％,转化率达９５％,是一种优良的电化学催化剂．     

NaAlO2含量对ZAISil2Cu2Mgl铝合金Na2SiO3微弧氧化陶瓷膜性能的影响

为了进一步探明添加剂种类及含量对ZAlSil2Cu2Mgl铝合金微弧氧化陶瓷膜性能的影响,在Na2SiO,电解液中,添加不同浓度的NaAlO2进行了微弧氧化,利用能谱仪（EDS）分析了陶瓷膜表面元素含量,用扫描电镜（SEM）观察其表面形貌,以x射线衍射仪（XRD）分析了膜的相组成,并测试了膜的厚度、硬度和极化曲线;研究了NaALO2添加量对微弧氧化陶瓷膜特性的影响。结果表明,随着NaAlO2添加量的增加,陶瓷膜表面微孔尺寸变小,表面Al,O元素含量下降;起弧电压和最终氧化电压下降;陶瓷膜厚度增加,硬度和耐蚀性先提高后下降;陶瓷膜的相组成改变不明显。NaALO2添加量为1g／L时陶瓷膜的综合性能最好。     

Gd2O2S-HoCu2复合磁性蓄冷材料的制备研究

采用粉末冶金方法首次制备了Gd2O2S-HoCu2金属-陶瓷复合性蓄冷材料。结果表明，将Gd2O2S与HoCu2两种磁性蓄冷材料粉末按照一定比例混合，经球磨处理后压制成块，在氩气保护气氛下1100℃保温30min进行真空烧结，可制备成Gd2O2S-HoCu2金属-陶瓷复合磁性蓄冷材料，新型的金属-陶瓷复合磁性蓄冷材料由GOS与HoCu2两相构成，其比热性能良好，作为3～10K温区附近的蓄冷材料使用非常具有实用价值。     

SiCp-WSi2/MoSi2复合材料的室温力学性能

为了提高MoSi2的室温断裂韧性,将Si、Mo、W和C四种粉末混合后通过"原位反应热压"一次热压工艺制备了两种不同体积配比的SiCp-WSi2/MoSi2复合材料试样,测定了复合材料试样和纯MoSi2试样的室温.断裂韧性(KIC)与显微硬度(HV);采用X射线衍射(XRD)、扫描电镜(SEM)等方法研究了该工艺下试样的结构、组织以及断口形貌与断裂韧性问的相互关系.结果表明,SiC的复合化和W元素的合金化能使SiCp-WSi2/MoSi2复合材料晶粒细化,硬度、室温断裂韧性比纯MoSi2明显提高,断裂韧性最高值达5.88 MPa·m1/2.并对复合材料的硬化、韧化机理分别进行了分析.     

等离子喷涂Al_2O_3-TiO_2-ZrO_2涂层及其耐磨损性能

采用液相喷雾造粒法将准微米Al_2O_3,TiO_2,纳米ZrO2颗粒团聚成微米粉体,并用等离子喷涂技术制备了含纳米颗粒的Al_2O_3-TiO_2-ZrO_2陶瓷涂层.在MM200型环块磨损试验机上进行了常温干摩擦试验,比较了含有纳米颗粒的Al_2O_3-TiO_2-ZrO_2涂层和传统Al_2O_3-TiO_2陶瓷涂层的耐磨损性能,并用扫描电镜观察磨损后的磨痕形貌.结果表明,含有纳米颗粒的涂层耐磨损性能明显优于传统的陶瓷涂层.     

MgO-Al2O3-SiO2-TiO2-Y2O3玻璃的弹性模量

根据硬盘基板用材料的要求,制备了MgO-A12Oa-SiO2-TiO2-Y2Oa高弹性模量玻璃(120GPa).玻璃的弹性模量随组成的变化服从Makishima-Mackenzie理论,MgO、A12O3、TiO2、Y2O3等具有较高单位体积离解能的氧化物有利于提高玻璃的弹性模量.但玻璃弹性模量的理论计算值低于测试值.这是因为Makishima-Mackenzie理论没有考虑玻璃内阳离子的具体配位状态,对MgO、Y2O3堆积密度因子的推导存在误差.因此利用Makishima-Mackenzie理论发展高弹性模量玻璃时应对MgO、Y2O3等氧化物的计算进行修正.     

Eu~(2+),Mn~(2+)在CaZn_2(PO_4)_2中的发光及Eu~(2+)→Mn~(2+)能量传递

Mn2+作为激活剂加入一些基质中,发光比较弱。因此常常选择使用合适的敏化剂来提高Mn2+的发光效率,本文的研究目就是验证Eu2+是Mn2+的良好的敏化剂。采用高温固相法合成了Eu2+,Mn2+掺杂激活的CaZn2(PO4)2荧光粉,并对其发光性质进行了研究。单掺杂Eu2+时呈现发射峰位于504nm的带谱,属于Eu2+离子的5d-4f能级跃迁辐射,激发峰位于380nm,属于Eu2+的f-d跃迁特征激发谱带。单掺Mn2+时CaZn2(PO4)2不发光。当Eu2+和Mn2+共掺时,出现Mn2+的673nm发射峰,样品发红光,表明Eu2+对Mn2+的发光有很强的敏化作用。研究了Eu2+和Mn2+掺杂浓度对激发光谱和发射光谱的影响,证明在CaZn2(PO4)2:Eu2+,Mn2+中Eu2+对Mn2+的能量传递属于共振能量传递。     

Elastic and Electronic Properties of Superconducting CaPd 2 As 2 and SrPd 2 As 2 vs. Non-superconducting BaPd 2 As 2

The first-principles calculations were performed to predict the elastic and electronic properties of the superconducting ThCr₂Si₂-type phases CaPd₂As₂ and SrPd₂As₂ in comparison with the non-superconducting CeMg₂Si₂-type phase BaPd₂As₂. Besides, the same properties were compared for CeMg₂Si₂- and ThCr₂Si₂-type polymorphs of BaPd₂As₂. We found that all these phases are mechanically stable and belong to soft materials with low hardness. The near-Fermi region is formed by the valence states of the blocks [Pd₂As₂] with decisive contributions of Pd 4d states. The values of N(E _F) increase in the sequence: CaPd₂As₂ < SrPd₂As₂ < BaPd₂As₂, i.e. in the reverse sequence relative to the transition temperatures T _C. Thus, the change in T _C cannot be explained by the electronic factor, i.e. by the simple correlation T _C～N(E _F). Most likely the decrease in T _C in the sequence CaPd₂As₂ → SrPd₂As₂ and the absence of a superconducting transition in BaPd₂As₂ are related to the structural factors and the peculiarities of the electron–phonon coupling mechanism.     

Preparation of ZrO2-CeO2 and HfO2-CeO2 nanopowders

We prepared weakly agglomerated powders of ZrO₂-CeO₂ and HfO₂-CeO₂ solid solutions 5–8 nm in particle size, consisting of monoclinic and tetragonal phases. After heat treatment at 1200°C, the crystallite size was 30 and 14 nm, respectively. We also examined the effect of precipitate freeze drying on the crystallization of hafnia-based solid solutions containing up to 20 mol % CeO₂.     

VLE data for CO2-CF2Cl2, N2-CO2, N2-CF2Cl2 and N2-CO2-CF2Cl

Knowledge about vapour-liquid (VLE) is required as a basis of reliable calculations for separation processes. Correlations available for the prediction of T, p, x, y data are less accurate for mixtures at high pressures and mixtures containing supercritical components. The results of VLE experiments are reported and compared with data calculated with equations of state.     

Thermal diffusion in binary mixtures H2-CCl2F2 and H2-CHClF2

Thermal diffusion coefficients were measured in two gaseous mixtures, in which one component was close to the critical temperature, in the pressure range (19.6–127.4)·10⁴ N/m² and at a freon concentration of 0.25–0.8.     

SiO2—TiO2—ZrO2系涂层的制备及其特性

用溶胶－凝胶法（sol-gel method）在不锈钢表面制备了SiO2-TiO2-ZrO2系无机氧化膜（STZ）。用DTA／TG、IR、XRD和SEM等手段研究了涂层制备时由凝胶向玻璃态的转变以及涂层薄膜的显微结构特点，考察了涂层对基体的保护效果。试验结果表明，在溶胶至凝胶最终转变为无机氧化物的过程中形成了无机网络，Si^4 和Zr^4 充当了网络骨架的形成离子。涂层为无定型玻璃态，其间混有石英、锐钛矿或金红石等微晶。     

SiO2-TiO2-ZrO2涂层的制备及其特性

用溶胶-凝胶法(sol-gel method)在不锈钢表面制备了 SiO\-2-TiO\-2-ZrO\-2系无机氧化膜(STZ).用DTA/TG、IR、XRD和SEM等手段研究了涂层制备时由凝胶向玻璃态的转变以及涂层薄膜的显微结构特点,考察了涂层对基体的保护效果. 试验结果表明,在溶胶至凝胶最终转变为无机氧化物的过程中形成了无机网络,Si4+ 和Zr4+充当了网络骨架的形成离子.涂层为无定型玻璃态,其间混有石英、锐钛矿或金红石等微晶.     

晶态骨架介孔CeO2和CeO2-ZrO2的合成与结构表征

以乙酸铈、乙酸锆为无机源,嵌段共聚物P123为模版剂,采用溶胶-凝胶法合成了介孔CeO2及CeO2-ZrO2复合体,用XRD、氮气吸附脱附、TEM、HRTEM、SAED等对材料进行了表征.结果表明,所得介孔CeO2具有规则的晶态孔道结构,孔径约在10nm左右,特别是其孔壁晶粒高度定向排列且平行于孔道方向.原位高温TEM观测表明,该介孔CeO2在800℃仍具有很高的孔道完整性.掺杂ZrO2后发现,在ZrO2摩尔含量低于30%时仍具备高度定向排列结构,高于30%时骨架晶粒取向逐渐趋向无序化.     

Carbon-thermal reduction and nitridation of mixtures of SiO2 and Al2O3 · 2H2O

Sialon powders have been prepared by heating mixtures of SiO₂, Al₂O₃ 2H₂O and carbon in flowing nitrogen at 1470° C. The nitrogen content in the product powder increased with increasing added carbon, and was independent of both the flow rate of nitrogen gas and the surface area of pellet. The amount of SiO lost increased with an increase in the flow rate of nitrogen gas and surface area of the pellet and with a decrease in the amount of added carbon. A major part of the SiO evolved by the carbon reduction was trapped by carbon then consumed by carbon reduction and nitridation to form the sialon powder. The rest of the SiO was carried out of the system by the nitrogen gas. The amount of SiO lost and the nitrogen content can be estimated using the residual carbon content.