Al2O3/ZrO2/ZrSiO4复合材料的研究

在Al2O3颗粒补强锆英石陶瓷的研究基础上,探讨了Al2O3与ZrO2共同对锆英石陶瓷的协同补强增韧行为.制备的锆英石基复合材料的室温抗弯强度和断裂韧性分别可达383.31MPa、4.39 MPa·m12.采用XRD分析了复合材料的相组成,采用SEM观察复合材料的断面形貌.结果显示:ZrSiO4为主要晶相,另外还有少量Al2O3和ZrO2存在;第二种增强体ZrO2的最佳引入量为20％(质量分数);确定复合材料的强韧化是由Al2O3和ZrO2颗粒引起的裂纹偏转、微裂纹增韧与ZrO2颗粒引起的相变增韧共同作用而实现的,断裂方式主要为穿晶断裂.     

超重力下燃烧合成大体积凝固态Al2O3/ZrO2（4Y）研究

通过在铝热剂中引入ZrO2(4Y)混合粉末,以超重力下燃烧合成方式,制备出Al2O3/ZrO2(4Y)自生复合陶瓷板材,并研究了复合陶瓷微观结构、生长机理与力学性能.XRD、SEM与EDS结果显示,Al2O3/32%ZrO2(4Y)复合陶瓷基体为亚微米t-ZrO2纤维成三角对称分布其上、取向各异的棒状共晶团,而Al2O3/37%ZrO2(4Y)复合陶瓷则以分布均匀的微米级t-ZrO2球晶为基体.Al2O3/32%ZrO2(4Y)复合陶瓷的强化归因于小尺寸共晶团边界及残余压应力增韧、相变增韧机制引发的高断裂韧性所致;同时,细小t-ZrO2球晶所具有的小尺寸缺陷及相变增韧与微裂纹增韧机制所引发的高断裂韧性也使Al2O3/37%ZrO2(4Y)复合陶瓷得以强化.     

3Y-TZP/mullite-Alumina复合陶瓷的韧性及增韧机制

为了研究3Y TZP为基体的3Y TZP/mullite Alumina复合陶瓷的断裂韧性及其增韧机制,将3Y TZP、mullite、Alumina3种粉料球磨混合,经干压、等静压成型,在1480℃,4h无压烧结,通过改变Alumina/mullite体积比,得到了不同断裂韧性的陶瓷复合材料,利用XRD与SEM技术分析了复合材料的成分及微观结构.研究结果表明:Al2O3/mullite体积比影响复合材料中四方氧化锆(t ZrO2)向单斜氧化锆(m ZrO2)转变的相变量、复合材料的微观结构和t ZrO2晶面间距,进而影响材料的断裂韧性;用单边切口梁法测试复合材料断裂韧性(KIC)为9 26～10 4MPa·m1/2;此系统中存在ZrO2相变增韧、非相变第二相颗粒增韧等机制.     

烧结温度对20%ZrO_2(3Y)/Al_2O_3复相陶瓷力学性能和微观结构的影响

20%纳米ZrO2(3Y)粉末加入到高纯亚微米Al2O3粉中,采用高压干压成型方法和恒速升温多阶段短保温烧结方法制备出不同烧结温度下的复相陶瓷。研究烧结温度对复相陶瓷力学性能的影响,通过XRD,EDS和SEM对复相陶瓷进行元素组成和微观结构分析。结果表明:烧结温度在很大程度上影响着复相陶瓷的力学性能和微观结构,常压烧结1600℃保温8h时,相对密度、维氏硬度和断裂韧性达到最大,分别为98.6%,18.54GPa和9.3MPa·m1/2,而基体晶粒尺寸为1.4~8.1μm,ZrO2相变量为34.6%。1600℃下复相陶瓷具有优质的微观结构,断裂方式为沿晶-穿晶混合断裂模式。ZrO2(3Y)粉体的加入,从相变增韧、内晶型颗粒增韧和裂纹偏转等多个方面提高了复相陶瓷的断裂韧性。     

细晶(Y/Ce,Mg)-PSZ/MgAl2O4陶瓷制备工艺及性能的研究

在化学共沉淀法制备细晶PSZ陶瓷的基础上，用工业ZrO2作原料，以MgO、Y2O3、CeO2及α-Al2O3作为复合稳定剂及添加剂，采用机械球磨混合法，并在制备过程中部分用去离子水代替乙醇作为球磨介质，探讨了水磨混合法制备粉料的可行性．实验结果表明：在较低的固溶烧结温度（1550℃）下，经1100℃适当时间热处理，亦可制备出具有较好力学性能的细晶PSZ陶瓷材料，其室温强度约700MPa，断裂韧性在15MPa·m1／2左右；在（180℃，1MPa）水热条件下，采用CeO2作复合稳定剂的PSZ陶瓷材料要比Y2O3复合稳定的PSZ材料更具良好的抗水化性．     

Al2O3-ZrO2(3Y)-SiC纳米复合材料的制备及性能

本文研究了非均相沉淀法制备Al2O3－ZrO2（3Y）－SiC复合粉体的工艺过程,认为粉体的理烧温度是至关重要的,热压烧结得到了致密的Al2O3－ZrO2（3Y）－SiC纳米复合材料,ZrO2的加入对烧结温度的影响不大．通过TEM观察,SiC颗粒均匀分散于材料中,大的ZrO2颗粒位于Al2O3晶粒间,小的圆形ZrO2颗粒位于Al2O3晶粒内,一部分Al2O3晶粒呈非等轴状．80Wt％Al2O3－15wt％ZrO2－5Wt％SiC纳米复合材料的抗弯强度可达555MPa,韧性为3.8MPa．m1／2.     

预烧结温度对注浆成型3Y-TZP齿科陶瓷可加工性的影响

基于注浆成型技术采用两次烧结法(预烧结—加工—最终烧结)制备3Y-TZP(3%(摩尔分数)Y2O3稳定ZrO2)齿科陶瓷材料,研究了预烧结温度对其收缩率、维氏硬度、断裂韧性和磨损量的影响,结合脆性指数和磨损量对其可加工性进行评价,并表征了最终烧结后3Y-TZP微观形貌和力学性能。结果表明,随着预烧结温度的提高,3Y-TZP的收缩率、维氏硬度和 断裂韧性均 增加,而单 位面积磨损 量下降;1250℃预烧结的3Y-TZP脆性指数为244.6,高速涡轮牙钻钻孔后边缘清晰、无崩裂现象;1500℃完全烧结后晶粒尺寸增大,维氏硬度为(9339.4±823.2)MPa,断裂韧性为(3.66±0.41)MPa·m1/2,可以满足齿科材料对力学性能的要求。     

超重力下燃烧合成Al2O3-ZrO2(Y2O3)共晶陶瓷组织性能演化

采用超重力下燃烧合成工艺进行Al2O3-ZrO2 (4Y)共品陶瓷的制备,研究了Al2O3-ZrO2(4Y)共晶陶瓷的凝固行为、组织演化与力学性能的关系.XRD、SEM与EDS分析显示陶瓷基体组织是由表层的微纳米晶组织和心部的ZrO2四方相微米球品组织组成.陶瓷表层微纳米品组织的形成是因Al2O3高熵相率先形核和Al2O3各向异性生长,诱发Al2O3-ZrO2(4Y)小平面-小平面共晶生长所致;处于陶瓷心部的ZrO2四方相微米球晶组织则是因ZrO2高温立方相快速生长,导致Al2O3和ZrO2独立长大所致.力学性能测试结果表明因陶瓷凝固行为引起的显微组织演化,使其表层具有最大的维氏硬度(20.2GPa),而其心部则具有最高的断裂韧性(18.5±1.6MPa·m1/2),陶瓷弯曲强度达至1268±112MPa.     

用包裹纳米复合粉体制备ZTA陶瓷

用非均匀成核法和液相共沉淀法相结合的方法制得ZrO2(3Y)包裹Al2O3纳米复合粉体,经干压成型,常压烧结制备ZTA复相陶瓷.通过XRD、TEM对粉料的物相组成和显微形貌进行表征,研究了包裹粉体中煅烧温度和ZrO2含量对烧结体的烧结性能和力学性能的影响.结果表明:随着前驱体粉料煅烧温度的升高,包裹后的Al2O3-ZrO2(3Y)复合陶瓷粉体比表面积降低,粒径变大;ZrO2含量为20wt.%的Al2O3-ZrO2(3Y)复合陶瓷粉体,经过1000℃锻烧后,干压成型制备的烧结样品的抗弯强度和断裂韧性分别高达454.9MPa和11.6MPa·m1/2,SEM观察结果表明烧结体结构致密.     

Ni和Ti的添加对Al2O3-Ti（C,N）复合材料性能的影响

研究了Ni和Ti的添加对真空热压烧结方法制备的Al2O3-Ti(C,N)陶瓷基复合材料的显微组织和力学性能的影响.发现添加Ni和Ti的复合材料主要由Al2O3、Ti(C,N)和Ni组成,没有发现存在金属Ti.Ti由于非常活泼,在热压烧结过程中可能与石墨模具产生的含C气氛反应生成TiC,或与高温下Ti(C,N)的少量分解产生的N2气氛反应生成TiN,这有利于减少复合材料中的气孔.适量添加Ni可通过液相烧结促进复合材料的致密化,提高复合材料的相对密度,并能通过产生裂纹偏转和裂纹桥联提高复合材料的断裂韧性.热压温度为1550℃、等摩尔比的Ni和Ti混合粉末添加量为5vol%时,Al2O3-Ti(C,N)-Ni-Ti复合材料的相对密度为99.6%,硬度为21GPa,抗弯强度为818MPa,断裂韧性为8.1 MPa.m1/2.     

Liquid-vapor equilibria in the binary systems AsCl3-1,1,1-C2H3Cl3, AsCl3-1,1,2-C2H3Cl3, and AsCl3-C2HCl3O

Experimental data are presented on the liquid-vapor equilibria in the binary systems AsCl₃-1,1,1-trichloroethane, AsCl₃-1,1,2-trichloroethane, and AsCl₃-dichloroacetyl chloride.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 4, 2005, pp. 503–507.Original Russian Text Copyright © 2005 by Potolokov, Nikolashin, Menshchikova, Fedorov.     

Synthesis and characterization of Mg3Cr2Si3O12-Fe3Cr2Si3O12 garnet solid solutions

Homogeneous garnet Fe₃Cr₂Si₃O₁₂ and its solid solutions with garnet Mg₃Cr₂Si₃O₁₂ (four intermediate samples) were synthesized at high pressure. Garnet Mg₃Cr₂Si₃O₁₂ was not synthesized in pure form. The sample contained traces of the two phases, MgSiO₃ and Cr₂O₃. The products were investigated by means of X-ray powder diffraction and differential scanning calorimetry. Molar volumes of the solid solutions as a function of composition fit linear regression with an accuracy of 0.2%. No difference in heat capacity within the limits of experimental error was detected. In thermodynamic evaluations, the garnet solid solutions Fe₃Cr₂Si₃O₁₂-Mg₃Cr₂Si₃O₁₂ may be treated as ideal solid solutions.     

Varistor properties of ZnO-Pr6O11-CoO-Cr2O3-Y2O3-In2O3 ceramics

The varistor properties of the ZnO-Pr₆O₁₁-CoO-Cr₂O₃-Y₂O₃-In₂O₃ ceramics were investigated for different concentrations of In₂O₃. The increase of In₂O₃ concentration slightly increased the sintered density (5.60-5.63 g/cm³) and slightly decreased the average grain size (3.4-2.9 μm). The breakdown field increased from 6023 to 14822 V/cm with increasing concentration of In₂O₃. The nonlinear coefficient increased from 17.6 to 44.6 for up to 0.005 mol%, whereas the further doping caused it to decrease to 36.8. In₂O₃ acted as an acceptor due to the donor concentration, which decreases in the range of 1.02 × 10¹⁷ to 0.24 × 10¹⁷/cm³ with increasing concentration of In₂O₃.     

PbSbBiS4-Sb2S3 and PbSbBiS4-Bi2S3 joins in the PbS-Sb2S3-Bi2S3 system

Phase equilibria along the PbSbBiS₄-Sb₂S₃ and PbSbBiS₄-Bi₂S₃ joins of the PbS-Sb₂S₃-Bi₂S₃ system have been studied for the first time using differential thermal analysis, X-ray diffraction, microstructural analysis, microhardness tests, and density measurements, and the phase diagrams of the joins have been mapped out. The joins are shown to be pseudobinary with limited series of terminal solid solutions. The solid solutions are p-type semiconductors.     

Phase developments in the Pb(Zn1/2W1/2)O3-Pb(Zn1/3Ta2/3)O3-Pb(Zn1/3Nb2/3)O3 pseudo-ternary system

The phase stability ranges in the B-site precursor (Zn_1/2W_1/2)O₂-(Zn_1/3Ta_2/3)O₂-(Zn_1/3Nb_2/3)O₂ were determined by X-ray diffraction (XRD), where wolframite, tri-αPbO₂, and columbite phases were identified. Next attempts were carried out (with the addition of PbO) for the system Pb(Zn_1/2W_1/2)O₃-Pb(Zn_1/3Ta_2/3)O₃-Pb(Zn_1/3Nb_2/3)O₃, where the perovskite phase did not develop in the entire compositions investigated. Instead, only the Pb₂WO₅ and pyrochlore phases (along with ZnO) resulted.     

Influence of BaZrO3, MnCO3 additives on dielectric properties and microstructure of Ba(Zn1/3Nb2/3)O3 ceramics and Ba(Zn1/3Nb2/3)O3-Sr(Zn1/3Nb2/3)O3 solid solutions

The effect of BaZrO₃, MnCO₃ additives on the dielectric properties, sintering temperature and microstructure of Ba(Zn_1/3Nb_2/3)O₃ (BZN) and Ba(Zn_1/3Nb_2/3)O₃-Sr(Zn_1/3Nb_2/3)O₃ (BSZN) ceramics was studied in this paper. It indicates that both BaZrO₃ and MnCO₃ can lower the sintering temperature of the ceramics and accelerate the crystallization of BZN and BSZN. The dielectric constant ɛ _r increases after MnCO₃ added, but decreases when BaZrO₃ added alone. The existence of MnCO₃ can modulate the temperature coefficient of capacitance τ _c toward positive, while BaZrO₃, can make c more negative. MnCO₃ and BaZrO₃ can restrain the appearance of the second phase; while BaZrO₃, can prevent the appearance of the superstructure. In the BSZN system, when 1 mass % MnCO₃ added, sintering temperature(t _s ) is lowered to 1240°C. In this study, the best sample that has the excellent properties is sample 5 with dielectric properties of ɛ _r = 43.6, τ _c = −8 × 10⁻⁶ °C⁻¹ and tan δ = 0.6 × 10⁻⁴ (1 MHz). The sintering temperature of BZN and BSZN system can be lowered to less than 1300°C.     

Elastic modulus and hardness of CaTiO3, CaCu3Ti4O12 and CaTiO3/CaCu3Ti4O12 mixture

Three ceramic systems, CaTiO₃ (CTO), CaCu₃Ti₄O₁₂ (CCTO) and intermediate nonstoichiometric CaTiO₃/CaCu₃Ti₄O₁₂ mixtures (CTO.CCTO), were investigated and characterized. The ceramics were sintered at 1100 °C for 180 min. The surface morphology and structures were investigated by XRD and SEM. Elastic modulus and hardness of the surfaces were studied by instrumented indentation. It was observed that CCTO presented the higher mechanical properties (E = 256 GPa, hardness = 10.6 GPa), while CTO/CCTO mixture showed intermediate properties between CTO and CCTO.     

(La2/3Ca1/3)(Mn(3-x)/3Fex/3)O3体系磁电阻行为的研究

通过系统地测量(La     

(La2/3Ca1/3)(Mn(3-x)/3)Fex/3)O3体系磁电阻行为的研究

通过系统地测量（La2/3Ca1/3）（Mn（3-x）／3Fex／3）O3（x＝0、0.1、0．2、0．3的体系样品的电阻率-温度关系以及一定温度下磁电阻率与磁场的关系,发现随x的变化其磁电阻率峰和电阻率峰均发生位移,磁电阻率峰值增大,并伴生磁电阻率峰展宽效应．作者认为由于Fe的替代,引起体系中Mn3 ／Mn4 比率及磁矩的变化,加之外场对磁有序结构的调制作用,从而影响了Mn3 －O－Mn4 的双交换作用,最终导致磁电阻行为发生变化．     

Microstructures of YBa2Cu3O7/La0.7Ca0.3MnO3 and La0.7Ca0.3MnO3/YBa2Cu3O7 bi-layers grown on (001)LaAlO3

Epitaxial YBa₂Cu₃O₇/La_0.7Ca_0.3MnO₃ (YBCO/LCMO) bi-layers and La_0.7Ca_0.3MnO₃/YBa₂Cu₃O₇ (LCMO/YBCO) bi-layers were grown on (001)LaAlO₃ by pulsed laser deposition, and their microstructures were compared by transmission electron microscopy investigation. In the YBCO(100 nm)/LCMO(150 nm) bi-layers, the LCMO layer consists of columnar grains of ~ 17 nm in diameter and contains mixed orientation domains of [100]_c, [010]_c and [001]_c. The YBCO layer is totally c-axis oriented and the YBCO lattices are tilted − 2.5° to + 2.5° as they grew on the rough surfaces of LCMO columnar grains. For the LCMO(140 nm)/YBCO(140 nm) bi-layers, the LCMO/YBCO interface is sharp and flat. The initial 12-nm thickness of the YBCO layer is composed of c-axis oriented domains, and the upper part of YBCO layer is [100] oriented. The LCMO layer was predominantly [001]_c oriented while [100]_c-oriented domains were occasionally observed.