(ZrO2)0.96(Y2O3)0.03(Al2O3)0.01陶瓷的制备及性能研究

采用化学共沉淀法制备（ZrO2）0.96（Y2O3）0.03（Al2O3）0.01的粉末, 在不同的升温速率、不同的烧结时间和不同的烧结温度等烧结工艺下制备出（ZrO2）0.96（Y2O3）0.03（Al2O3）0.01三相体系复合陶瓷. 经研究发现, 在升温速率和降温速率均为5 ℃·min^-1 的烧结制度下, 1550 ℃烧结时, 可以得到抗弯强度达998 MPa, 抗热震次数达33次, 相对密度达96%和电性能较好的烧结体.     

Acid dissolution of willemite (Zn,Mn)2 SiO4) and hemimorphite (Zn4Si2O7(OH)2 H2O)

The influence of temperature, pH, acid type, and surface area on the kinetics of the acid dissolution of natural and synthetic willemites and natural hemimorphites has been investigated. Specific rate constants, based upon areas determined by krypton adsorption measurements, were estimated from the experimental data obtained. For both willemite and hemimorphite, the rates of dissolution in different acids are shown to be related to the relative strengths of zinc-acid anion complexes. The reactivity of willemite toward acids increases with increasing replacement of zinc by manganese. Mixed chemical/diffusion control is responsible for the observed rates of willemite dissolution under the conditions studied (HNO₃, HCl, HClO₄, H₃PO₄, H₂SO₄, pH 0.31 to 3.00,T 21 to 94 °C). Estimates of the relative contributions of chemical and diffusional resistances to the overall rate have been made for the dissolution of manganese-free willemite in sulfuric acid solutions. The experimentally measured rates have been demonstrated to be in reasonable agreement with predicted overall dissolution rates. Proposals are made regarding the nature of the diffusion and chemical steps involved in the dissolution process. Hemimorphite was found to be considerably more reactive than willemite and its dissolution is primarily diffusion controlled under the conditions studied (T 20 to 76 °C, pH 2 to 3.5). Formerly a Postgraduate Research Student, Department of Metallurgy and Materials Science, Royal School of Mines, Imperial College, London     

Activities of FexO in CaO‐(Na2O)0.1875(K2O)0.0625(Al2O3)0.25(SiO2)0.5‐FexO Pseudo‐Ternary Slags

Activities of Fe_xO in CaO‐(Na₂O)_0.1875(K₂O)_0.0625(Al₂O₃)_0.25(SiO₂)_0.5‐Fe_xO pseudo‐ternary slags were determined at 1673K by using a solid‐oxide galvanic cell; The substitution of (Na₂O)_0.1875(K₂O)_0.0625(Al₂O₃)_0.25(SiO₂)_0.5 for CaO has an effect of raising the Fe_xO activities.     

Measuring and Modeling Viscosity of CaO-Al2O3-SiO2(-K2O) Melt

The effect of K₂O on viscosity in CaO-SiO₂-Al₂O₃ melt has been measured by a rotating spindle viscometer. It is indicated from the experimental results that viscosity first increases then decreases with the increasing content of K₂O; the maximum viscosity occurs in the field of K₂O/Al₂O₃?>?1. After gradually adding K₂O, the transformation of bridging oxygen (from being bonded with Al³⁺ ion charge compensated by Ca²⁺ ion to that compensated by K⁺?ion, for the higher priority of K⁺ ion relative to Ca²⁺ ion) increases the viscosity, whereas the increase of content of nonbridging oxygen decreases viscosity. The two factors lead to the complicate variation behavior of viscosity. The viscosity model proposed in our previous papers describes this phenomenon well.     

Syntheses and Structures of Two Heteronuclear Complexes with Glycine {[CuEr(Gly)_5(H_2O)_2](ClO_4)_5·H_2O}_n and {[Cu_2Gd_2(Gly)_10 (H_2O)_4](ClO_4)_10·4H_2O}_n

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Investigation on pumping oxygen characteristics of (Bi2O3)0.73(Y2O3)0.27 solid electrolyte

(Bi2O3)0.73(Y2O3)0.27 fine powders prepared by wet chemical precipitation method were cold isostatically pressed to form solid electrolyte tubes, and sintered at 900 ℃ for 10 h in the air. Their pumping oxygen characteristics in non-dehydrated Ar gas were investigated, where a ZrO2 (Y2O3 stabilized) oxygen sensor was used to measure the oxygen partial pressure Po2. The results showed that the Po2 value reached magnitudes of 1×10-20-1×10-10 Pa at the applied pumping oxygen voltage of 0.5 V, 1×10-37-1×10-27 Pa at 1.0 V and 1×10-53-1×10-47 Pa at 2.0 V within the temperature range from 550 to 650 ℃. Moreover, no cracks were found in the tested solid electrolyte tubes. Thus, the Bi2O3-Y2O3 system might be used in solid electrolyte oxygen pump for purifying gases.     

Thermal Shock Resistance of Al2 O3/ZrO2 (Y2O3) Composites

ZrO₂ containing 2% (mol fraction) Y₂O₃ and 3% (mol fraction) Y₂O₃ were added into Al₂O₃ matrix, compositing composites with 15% volume fraction of addictives mentioned above. The testing of property and analysis of SEM presented that, after vacuum sintering at 1550 °C, thermal shock resistance of two composites was superior to Al₂O₃ ceramic. The experiment showed that the properties of Al₂O₃ composites was higher than Al₂O₃ ceramic, and Al₂O₃/ZrO₂(3Y) was higher than Al₂O₃/ZrO₂(2Y) in thermal shock resistance. Improvement of thermal shock resistance of composites was attributed to many toughness machanisms of ZrO₂(Y₂O₃). By calculation, the fracture energy of Al₂O₃, Al₂O₃/ZrO₂ (2Y) and Al₂O₃/ZrO₂(3Y) was 38100.8 and 126.2 J·m⁻², respectively. Cracks initiation resistance (R') of Al₂O₃/ZrO₂(3Y) and Al₂O₃/ZrO₂(2Y) was higher than Al₂O₃ ceramic by 1.57 and 1.41 time, respectively, and cracks propagation resistance (R″″) was higher than Al₂O₃ ceramic by 1.46 and 1.38 time, respectively, which was corresponding to the results of residual strength.     

β-Cristobalite stabilization in (Na2O+Al2O3)-added silica

The metastable retention of β-cristobalite in sintered colloidal gel-derived silica powder with (Na₂O + Al₂O₃) addition has been confirmed by both X-ray diffractometry (XRD) and transmission electron microscopy (TEM). Selected-area electron diffraction patterns (SADP) for the chemically stabilized β-cristobalite revealed diffuse electron scattering intensities (DSIs) along 〈111〉 _{β(-cristobalite)}, 〈110〉 _β , and 〈100〉 _β , respectively, representing a disordered structure probably of dynamic nature. However, only 〈011〉 _{α(-cristobalite)} streaks are retained in α-cristobalite, which is characterized by the lamellar twins and formed after the β → α-cristobalite phase transformation. The mottled contrast in the crystalline and amorphous phase mixture of the sintered samples, as revealed by TEM, may be interpreted as the diagnostic feature for the existence of β-cristobalite. Microchemical analysis of the sintered samples, containing a mixture of α- and β-cristobalite in a glass matrix, suggests that the chemically stabilized β-cristobalite has a composition of Na₂O:Al₂O₃:SiO₂=7:16:77, which is higher in Al₂O₃-content than the starting powder. The stabilization mechanism of β-cristobalite in (Na₂O + Al₂O₃)-added silica is discussed in view of possible defect reactions. It is proposed that the stabilization involves the substitutional defect of Al′_si and the interstitial cations of Na_i and Al_i in the SiO₄ network.     

Infrarotspektroskopischer (IR) Nachweis von gelöstem Wasser in abgeschreckten Schlacken (Modellsysteme Na2O · P2O5 und Na2O · 2 B2O3)

Inf rarotspektroskopie von Wasser in Schlacken. Chemischer Bindungszustand von Wasser in Schlacken, Abhängigkeit der integralen Extinktion der OH-Banden vom Wasserdampfpartialdruck. Wasserstoff beim ESU-Verfahren.     

Al2O3/ZrO2(Y2O3)共晶复合陶瓷晶体生长机理

基于国外定向凝固氧化物/氧化物共晶复合陶瓷的晶体生长动力学行为的研究成果,阐述其动力学机制,分析动力学因素对微观结构形态的影响,探讨晶体生长热力学、动力学行为与微观结构形态之间的关系,同时结合以燃烧合成、快速凝固技术制备的新型高强韧Al2O3/ZrO2(Y2O3)共晶复合陶瓷,探讨共晶复合陶瓷在快速凝固条件下的晶体生长动力学行为.结合定向凝固与快速凝固两种晶体生长机制,得知过冷度、凝固界面前沿的温度梯度是影响晶体生长方式的重要因素,且受二者决定的凝固速率(即晶体生长速率)则决定材料的最终微观结构与形态.     

Mechanochemical Effects in Ln_2O_3-Ln(OH)_3-(H_2O)(Ln=La,Nd) System

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[Nd(PW11O39)(H2O)3](H2bpy)2·4H2O的水热合成及晶体结构

采用水热法合成稀土无机有机杂化化合物[Nd(PW11O39)(H2O)3 ](H2bpy)2·4H2O.采用NdCl3·6H2O,(NH4)3PW12O40·3H2O, 4,4'-联吡啶(bpy),和去离子水(摩尔比为4∶1∶4∶3900, pH=6)在130℃下进行水热反应3天,得到标题化合物的紫红色块状晶体,并进行了红外光谱分析,元素分析.用单晶X射线衍射法测得晶体结构,属三斜晶系,空间群为P-1,晶胞参数为a=1.18824(9) nm,b =1.35707(10)nm,c=1.77691(13)nm,α=71.551(2)°,β=82.478(2)°,γ=80.568(2)°.该晶体由无机的共价链∞1[Nd(PW11O39)(H2O)3]4- 和有机的二质子化的4,4'-联吡啶(H2bpy)2 及结晶水分子堆积而成的, 是一个新的稀土磷钨酸盐无机有机杂化化合物.     

Peripheral O2 diffusion does not affect V(O2)on-kinetics in isolated insitu canine muscle

To test the hypothesis that muscle O2 uptake (V(O2)) on-kinetics is limited, at least in part, by peripheral O2 diffusion, we determined the V(O2) on-kinetics in 1) normoxia (Control); 2) hyperoxic gas breathing (Hyperoxia); and 3) hyperoxia and the administration of a drug (RSR-13, Allos Therapeutics), which right-shifts the Hb-O2 dissociation curve (Hyperoxia+RSR-13). The study was conducted in isolated canine gastrocnemius muscles (n = 5) during transitions from rest to 3 min of electrically stimulated isometric tetanic contractions (200-ms trains, 50 Hz; 1 contraction/2 s; 60-70% peak V(O2)). In all conditions, before and during contractions, muscle was pump perfused with constantly elevated blood flow (Q), at a level measured at steady state during contractions in preliminary trials with spontaneous Q x Adenosine was infused intra-arterially to prevent inordinate pressure increases with the elevated Q x Q was measured continuously, arterial and popliteal venous O2 concentrations were determined at rest and at 5- to 7-s intervals during contractions, and V(O2) was calculated as Q x arteriovenous O2 content difference. PO2 at 50% HbO2 saturation (P50) was calculated. Mean capillary PO2 (Pc(O2)) was estimated by numerical integration. P50 was higher in Hyperoxia+RSR-13 [40 +/- 1 (SE) Torr] than in Control and in Hyperoxia (31 +/- 1 Torr). After 15 s of contractions, Pc(O2) was higher in Hyperoxia (97 +/- 9 Torr) vs. Control (53 +/- 3 Torr) and in Hyperoxia+RSR-13 (197 +/- 39 Torr) vs. Hyperoxia. The time to reach 63% of the difference between baseline and steady-state V(O2) during contractions was 24.7 +/- 2.7 s in Control, 26.3 +/- 0.8 s in Hyperoxia, and 24.7 +/- 1.1 s in Hyperoxia+RSR-13 (not significant). Enhancement of peripheral O2 diffusion (obtained by increased PcO2 at constant O2 delivery) during the rest-to-contraction (60-70% of peak V(O2)) transition did not affect muscle V(O2) on- kinetics.     

添加Y2O3的ZrO2增韧Al2O3陶瓷抗钢液腐蚀性能的研究

采用工业ZrO2和AlO3为原料,以Y2O3作为稳定剂,通过适当工艺制备出ZrO2增韧Al2O3(ZTA)陶瓷.主要研究了ZrO2和Y2O3稳定剂对ZTA陶瓷烧结性和抗钢液腐蚀性能的影响.实验结果表明:机械混合法引入的Y2O3在改善ZTA陶瓷的烧结性的同时,可以提高材料的抗钢液腐蚀性能;随ZrO2含量的增加,ZTA陶瓷的抗钢液腐蚀性能增强;材料中大量微裂纹的存在可以提高材料的韧性,但抗钢液腐蚀性能有所下降.