(Gd0.4Sm0.5Yb0.1)2Zr2O7陶瓷的合成与导热性能研究

以Gd2O3、Sm2O3、Yb2O3和ZrOCl2·8H2O为原料,采用化学共沉淀法合成了一种新型的多元稀土锆酸盐(Gd0.4Sm0.5Yb0.1)2Zr2O7陶瓷粉体,在1600℃无压烧结10h合成了致密的陶瓷块体.用X射线衍射仪(XRD)及场发射扫描电镜(SEM)对粉体和块体的微观结构进行了表征,采用激光闪射法测试了块体的导热性能.结果表明,制备的多元稀土锆酸盐陶瓷粉体具有焦绿石结构,晶粒细小,陶瓷的热导率明显低于一元稀土锆酸盐Sm2Zr2O7的热导率.该研究结果显示(Gd0.4Sm0.5Yb0.1)2Zr2O7多元稀土锆酸盐陶瓷有可能应用于热障涂层陶瓷层材料.     

不同干燥法掺铈超细氧化锆粉体的制备及表征

以ZrOC12·8H2O,Ce(NO3)3·6H2O为起始原料,氨水为沉淀剂,用共沉淀法结合喷雾干燥、真空冷冻干燥和超临界流体干燥技术制备了铈稳定四方氧化锆纳米级超微粉体,用热重-差示扫描量热计(TG-DSC)、X射线衍射分析仪(XRD)、物理吸附仪(Autosorb-MP-1)等仪器就制备方法对粉体的表面、孔径分布、晶粒尺寸和相对结晶度等性能进行了研究,结果表明:3种方法制得的初始粉体的颗粒尺寸分别为6.19,7.05和2.27 nm,比表面积分别为162.88,143.00,444.50 m2/g.从室温到900℃,随着煅烧温度的提高,SPD法和、VFD法制备的试样颗粒度显著粗化,而SCFD法制备的粉体粒度粗化则较慢.粉体材料的晶化温度、堆密度、相对结晶度和孔体积随制备方法的不同而有较大差异.     

（Gd0．4Sm0．5Yb0．1）2Zr2O7陶瓷的合成与导热性能研究

以Gd2O3、Sm2O3、Yb2O3和ZrOCl2·8H2O为原料，采用化学共沉淀法合成了一种新型的多元稀土锆酸盐（Gd0．4Sm0．5Yb0.1）2Zr2O7陶瓷粉体，在1600℃无压烧结10h合成了致密的陶瓷块体。用X射线衍射仪（XRD）／及场发射扫描电镜（SEM）对粉体和块体的微观结构进行了表征，采用激光闪射法测试了块体的导热性能。结果表明，制备的多元稀土锆酸盐陶瓷粉体具有焦绿石结构，晶粒细小，陶瓷的热导率明显低于一元稀土锆酸盐Sm2Zr2O7的热导率。该研究结果显示（Gd0.4Sm0.5Yb0.1）2Zr2O7，多元稀土锆酸盐陶瓷有可能应用于热障涂层陶瓷层材料。     

化学共沉淀法制备Ca_2Co_2O_5粉体

以硝酸钴和硝酸钙为原料,氢氧化钠为沉淀剂,利用化学共沉淀法制备Ca_2Co_2O_5粉体.采用TG-DSC、XRD、SEM和激光粒度分析仪(LPSA)等测试方法对粉体热分解过程,样品的物相、形貌和粒度分布进行表征.结果表明:在pH=13.2时制备的共沉淀粉,在750 ℃煅烧2 h后可获得单相层状的Ca_2Co_2O_5粉体,颗粒尺寸分布均匀,粒度在几百个纳米范围内.     

两步沉淀法合成Bi3.25La0.75Ti3O12(BLT)粉体及其表征

以五水硝酸铋(Bi(NO3)3·5H2O)、水合硝酸镧(La(NO3)3·nH2O)和钛酸四丁酯((C4H9O)4Ti)为原料,氨水为沉淀剂,分两步沉淀Ti离子和Bi、La离子,利用沉淀法合成了Bi3.25La0.75Ti3O12(BLT)粉体.利用差热分析(DTA)和热失重(TG)对两步沉淀法制备的前驱体粉体的热行为进行了分析,用X射线衍射(XRD)研究了其晶相演化过程,利用场发射扫描电子显微镜(FESEM)对BLT粉体粒度和形貌进行了观察.结果显示两步法制备的前驱体粉体经低温煅烧直接转化为单一的铋层状钙钛矿相BLT粉体,在700℃煅烧2 h合成的BLT粉体颗粒不大于100nm,颗粒间结合疏松,具有良好的分散性.     

不同方法制备的Gd2BaCuO5粉体性能比较

采用低温燃烧合成法(LCS)、共沉淀法和固相法合成了超细Gd2BaCuO5(Gd211)粉体,并对3种粉体的形貌、化学纯度、比表面积和粒度进行了比较。结果表明,LCS工艺制备的Gd211粉体粒度最小,团聚最轻。将以上3种粉体作为掺杂剂制备GdBa2Cu3O5(Gd123)超导块材,块材的微观形貌说明微细Gd211粉体的添加能有效减小Gd123块体中Gd211颗粒粒度,临界电流密度的比较表明LCS法所制粉体的添加比另外两种粉体更能有效提高临界电流密度。     

H2O2氧化对铈锆复合氧化物性能的影响研究

以廉价白云石为原料所制备的碳酸氢镁溶液作为沉淀剂合成铈锆复合氧化物,研究沉淀过程中双氧水氧化稀土锆混合料液对铈锆复合氧化物性能的影响。采用XRD、BET、SEM、TPR、O2脉冲化学吸附技术等手段研究了不同氧化时间对铈锆复合氧化物的晶型、比表面积、微观形貌、氧化还原性质和储放氧能力的影响。结果表明:双氧水氧化稀土锆料液不仅可以有效提高铈锆复合氧化物的比表面和高温稳定性,抑制其发生分相,而且可以提高铈锆复合氧化物表面活性氧的数量。随着氧化时间的延长,铈锆复合氧化物的比表面积、老化性能及储氧量增加,氧化时间为30 min时达到最佳效果,其600℃焙烧新鲜比表面积为111.3 m2/g,1000℃老化比表面积为32.9 m2/g,500℃时储氧量为315μmol O2/g;继续延长氧化时间,比表面积、老化性能及储氧量变化不大。     

化学共沉淀法制备BaMgA110O17:Eu2+荧光粉

以Ba(NO3)2,Mg(NO3)2·6H2O,Al(NO3)3·9H2O,Eu2O3和适量表面活性剂为原料,以NH4HCO3为沉淀剂,采用化学共沉淀法一次煅烧工艺,在1200℃下合成单相BaMgA110O17:Eu2+蓝色荧光粉。结果表明,化学共沉淀法的煅烧温度比传统的高温固相法降低了400℃左右,合成的荧光粉体色白、发光强度高、结构松散且无烧结现象,粒度主要分布在190～295nm之间。在254nm的紫外光激发下,BaMgA110O17:Eu2+的发射光谱最强峰在450nm左右;当Eu2+掺杂浓度为14%时,发光强度最大。     

超声雾化共沉淀法制备纳米YAG粉体

采用超声雾化共沉淀法,以Al(NO3).9H2O,Y(NO3).6H2O为原料,以聚乙二醇(PEG2000)作为分散剂,利用超声技术雾化钇铝混合液,形成气溶胶,与沉淀剂(氨水、碳酸氢铵)共沉淀反应制备纳米YAG粉体,制得粉体900、1000℃下煅烧3h,用XRD、SEM进行性能表征。结果表明:粉体均一转相;颗粒细小,平均尺寸为50nm;分散均匀,无明显硬团聚。     

稀土La对导电陶瓷BaPbO3组织和电性能的影响

采用化学液相共沉淀法制备了掺稀土La的BaPbO3导电陶瓷；用XRD及SEM对粉末的结构和组织进行了研究，从而确定了液相共沉淀法制取Ba1-xLaxPbO3的合成温度：同时讨论了稀土La对BaPbO3粉末合成过程及其电性能的影响。结果表明：采用液相共沉淀法能明显降低BamLaxPbO3粉末的合成温度，提高粉体的合成率，其合成温度大约在650℃左右：添加稀土La对BaPbO3的电阻率的影响呈“W”形状变化，当x=10％mol时Ba1-xLaxPbO3的焙烧温度、组织、电阻率均达到最佳。     

Fe-15Ce合金在H2-CO2、H2-H2S及H2-H2S-CO2气氛下的腐蚀

研究了600℃时Fe-15Ce合金在H2-CO2、H2-H2S及H2-H2S-CO2 3种气氛中的腐蚀行为，Fe-15Ce合金腐蚀后发生了Ce的内氧化或形成了复杂的腐蚀产物膜，而未出现Ce的选择性氧化或硫化，这主要是合金中存在着两相及Ce在Fe中极低的溶解度的结果。Fe-15Ce合金在本实验条件下的氧化-硫化腐蚀速度低于相同温度、压力下的纯硫化。     

用氢-氧取代氧-乙炔作焊接切割的必要性及可行性

阐述了用氢代乙炔的必要性．通过时HGQU2000／315火焰电孤焊割机的考察和试用证实了用氢代乙炔的可行性，比较了两种气体的性质并提出了使用特性差异和注意事项．提出了进一步探索的问题。     

Thermodynamics and phase diagrams in the binary systems Na2O-SiO2, Na2O-GeO2, Na2O-B2O3, Li2O-B2O3, CaO-B2O3, SrO-B2O3, and BaO-B2O3

We applied our model to the enthalpy of mixing data of the binary systems Na₂O-SiO₂, Na₂O-GeO₂, Na₂O-B₂O₃, Li₂O-B₂O₃, CaO-B₂O₃, SrO-B₂O₃, and BaO-B₂O₃. The most stable composition in the liquid, that is where the enthalpy of mixing is most negative, is with a metal-oxygen ratio of 4 to 3, for monovalent metals (Na and Li) and 3 to 4 for divalent metals (Ba and Ca) in liquid silicates or borates. The same applies to the CaO-SiO₂, CaO-Al₂O₃, PbO-B₂O₃, PbO-SiO₂, ZnO-B₂O₃, and ZnO-SiO₂ systems. The oxygen to metal ratio, its constant value in various types of systems, reflects and describes the structure of the liquid. Using the analyzed enthalpies of mixing data and the available phase diagrams, we calculated the enthalpies of formation of the various binary compounds. The results are in excellent agreement with data in the literature that were obtained from direct solid-solid calorimetry.     

IrO2-MnO2中间层Ti/RuO2-TiO2-SnO2电极制备及性能

通过热分解法制备了含IrO2-MnO2中间层Ti/RuO2-TiO2-SnO2电极,采用SEM、EDX、XRD、CV等检测方法对中间层进行表征,同时采用强化加速寿命试验对电极电化学稳定性进行表征。结果表明:450℃时前躯体完全氧化并形成固溶体,制备的中间层晶粒细小,表面结构致密,电化学孔隙率小。添加中间层使Ti/RuO2-TiO2-SnO2电极强化寿命由未加中间层的7.5h提高到995.8h,远高于国家标准20h。     

ACTIVITY OF La_2O_3 IN LIQUID La_2O_3-CaF_2 AND La_2O_3-CaF_2-CaO-SiO_2 SLAGS

用石墨为还原剂,将渣中La_2O_3还原入液态Sn,以测定1500℃下La_2O_3-CaF_2和La_2O_3-CaF_2-CaO-SiO_2渣中La_2O_3的活度.对La_2O_3-CaF_2系,并用Gibbs-Duhem积分法求得CaF_2的活度. 根据液态渣的离子结构模型,对上述二渣系中La_2O_3的活度数据进行了简单的讨论.     

Mechanoluminescence in BaSi2O2N2:Eu

Mechanoluminescence (ML), a general term for the phenomenon in which light emission occurs during any mechanical action on a solid, can be divided roughly into two classes: destructive ML and non-destructive ML. For practical use in high-end applications (e.g. pressure sensors), materials with non-destructive ML properties are preferred. This paper reports on the strong non-destructive ML in BaSi₂O₂N₂:Eu. When irradiated in advance with ultraviolet or blue light, this phosphor shows intense blue-green light emission upon mechanical stimulation such as friction or pressure. The ML has an emission band peaking at 498 nm, which is ～4 nm red-shifted compared to the steady-state photoluminescence. The origin of the ML is discussed and related to the persistent luminescence of BaSi₂O₂N₂:Eu. The same traps are responsible for both phenomena. Based on the occurrence of ML in this phosphor, we were able to show that the predominant crystallographic structure of BaSi₂O₂N₂:Eu belongs to space group Cmc2₁.     

氢分子在贮氢材料Li2MgN2H2表面的吸附与解离

采用第一性原理计算方法研究了Li-Mg-N-H体系贮氢材料的放氢产物Li2MgN2H2的吸氢反应过程中的过渡态、表面电子态密度和表面能。结果表明:氢分子在Li2MgN2H2低指数表面中最低能量(100)表面的Mg-Mg-Li穴位吸附位置能够形成最稳定的吸附结构并发生解离,氢分子吸附能为-0.1898eV,解离能约为0.84eV(81kJ/mol),表明该反应所需的反应活化能仍较高,吸氢反应速度缓慢。     

Thermodynamic evaluation of phase equilibria in the CaCl2-MgCl2-CaF2-MgF2 system

The phase diagram of the CaCl₂-CaF₂-MgCl₂-MgF₂ reciprocal ternary system was calculated thermodynamically from available data on the common-ion binary subsystems and from available data on the CaCl₂-MgF₂ join. This join is very nearly quasibinary and divides the system into two quasiternary systems: the CaCl₂-MgF₂-CaF₂ system with a ternary eutectic calculated at 724 +-5 °C and the CaC₂-MgF₂-MgCl₂ system with a ternary eutectic calculated at 561 +-5 °C.     

High temperature corrosion of Fe-Cr-Mn-alloys in H2-H2S and H2-H2O-H2S gas mixtures

The sulfidation of Fe-20% Cr-30% Mn, Fe-25%Cr-20%Mn and Fe-25% Cr was studied at 700°C in H₂-H₂S and the oxidation and sulfidation in H₂-H₂O-H₂S after preoxidation in H₂-H₂O. The sulfidation rate is strongly increased for the Mn-containing alloys, layers of (Mn,Cr)S and (Mn,Fe)Cr₂S₄ are formed. Also the oxidation rate is enhanced compared to Fe-25% Cr by formation of MnCr₂O₄ instead of Cr₂O₃. The sulfidation after preoxidation leads to internal and external sulfidation of the Mn-containing alloys. With increasing oxygen pressure p(O₂) = 10^?26…10^?22 atm. of the H₂-H₂O-H₂S mixtures the sulfidation is suppressed, for the higher oxygen pressure 10^?23 and 10^?22 atm. fast oxidation prevails under formation of MnCr₂O₄. Manganese cannot increase the sulfidation resistance of alloys, in spite of the stability and low degree of disorder of its sulfide, since the mixed sulfide (Mn,Cr)S is formed which has a high degree of disorder, high diffusivities and high growth rate according to the doping effect of trivalent Cr³⁺.     

The Quasi-Ternary System Cu2Se-Ga2Se3-GeSe2

The quasi-ternary system Cu₂Se-Ga₂Se₃-GeSe₂ was investigated using the methods of differential thermal and x-ray analysis. An isothermal section at 770 K and a liquidus surface projection of the phase diagram were constructed. The existence of the quaternary phase CuGaGeSe₄, the boundaries of solid solutions ranges of the system compounds were established.