细晶铈、镁复合稳定PSZ陶瓷的制备及性能研究

以工业ZrO2为主要原料,CeO2,MgO及α－Al2O3作为复合稳定剂及颗粒添加剂,采用机械球磨混合法制备粉料,进而在较低的固溶烧结温度（≤1550℃）下,经1100℃适当时间热处理,制备出具有较好力学性能的细晶PSZ陶瓷材料,其室浊度约655MPa,断裂韧性在15MPa.m^1/2左或,所制备细晶PSZ材料的临界热震温差△Tc在750℃左右,其中微裂纹增韧机制的存在对材料的抗热震性有积极作用,在（180℃,1MPa）水热条件下,采用CeO2作为复合稳定剂的PSZ陶瓷材料具有较好的抗水化性能。     

射频磁控溅射制备 HA(+ZrO2+Y2O3)/Ti6Al4V 复合生物活性涂层

采用射频磁控溅射法制备了HA（＋ZrO2＋Y2O3）／Ti6Al4V生物复合涂层．借助于XRD、SEM、FTIR和AFM等对溅射涂层的相组成、微观形貌和界面结合进行了研究，并以模拟体液试验探讨了涂层的生物活性．实验结果表明：磁控溅射的复合涂层呈非晶态，经过退火处理，可以使其转化为晶态；复合涂层的微观表面凹凸不平，并呈现网状结构和较多的孔隙，其孔隙直径约为0．5-2．0μm，孔隙面积占涂层表面积的30％-40％；HA（＋ZrO2＋Y2O3）／Ti6Al4V复合涂层的界面结合强度随（ZrO2＋Y2O3）复合颗粒含量的增大和溅射功率的提高而增强，最高可达59．6MPa．复合涂层在模拟体液中浸泡一段时间后，表面覆盖一层新生物质—含有CO^2-3的类骨磷灰石，其晶粒非常小，它与自然骨中无机相的结构成分相似，表明复合涂层具有良好的生物活性．     

纳米Ti0.8Cr0.2OxNy粉体的制备与表征

以沉淀法制备的纳米TiO2／Cr2O3复合粉体为原料，采用氨解法在800℃、氮化8h制备了纳米Ti0.8Cr0.2OxNy粉体．对纳米TiO2／Cr2O3复合粉体和合成的氧氮化物粉体用俄歇电子能谱(AES)、氮吸附比表面积(BET)、X射线衍射(XRD)、透射电子显微镜(TEM)、电子探针显微分析(EPMA)等方法进行了表征．结果表明：沉淀法可以制备出组成均匀的纳米TiO2／Cr2O3复合粉体，该复合粉体在800℃氮化8h可得到粒度为20～30nm的纯立方相Ti0.8Cr0.2OxNy纳米粉体，其比表面积达46．74m^2／g．     

Y1.34Gd0.60Eu0.06O3透明陶瓷材料的制备与发光性能

采用复合沉淀法制备了具有良好烧结活性的纳米级Y1．34Gd0．60Eu0．06O3粉体．经850℃／2h煅烧后，得到晶粒尺寸为30-40nm，且基本无团聚的Y1．34Gd0．60Eu0．06O3发光粉体，粉体比表面积为23m^2／g．该粉体经过适当的干压和等静压成型后，于1800℃以上温度烧结6h，可以获得Y1．34Gd0.60Eu0．06O3透明陶瓷．获得的透明陶瓷材料在波长250nm的紫外光激发下发射出较强的红光，发射主峰位于610nm，对应于掺杂Eu^3＋的^5D0-^7F2跃迁．     

TiN-Al2O3纳米复合材料的力学性能和导电性能

以纳米TiN和α-Al2O3粉体为原料,采用球磨混合法制备了纳米TiN-Al2O3复合粉体,通过热压烧结得到致密烧结体.研究了纳米TiN颗粒对Al2O3材料力学性能和导电性能的影响,实验结果表明:在Al2O3基体中加入15vol％TiN纳米颗粒时,Al2O3材料的弯曲强度和断裂韧性分别从370MPa和3.4MPa·m1/2提高到690MPa和5.1MPa·m1/2,随着TiN添加量的增加,复合材料的电阻率逐渐降低,在25vol％TiN时达到最低值(6.5×10-3Ω·cm).     

半化学法制备0.80Pb(Mg1/3Nb2/3)O3-0.20PbTiO3陶瓷的反应机理

采用半化学法制备了纯钙钛矿相的0．80Pb（Mg1/3Nb2/3）O3－0．20PbTiO3（简称为0．80PMN－0．20PT）陶瓷。反应前驱体是以硝酸镁的饱和溶液代替传统氧化物混合法中的氧化镁，与PbO、Nb2O5和TiO2混合球磨得到的。该前驱体的TG－DTG－DSC和XRD分析表明，半化学法的反应机理不同于传统氧化物混合法和二次合成法的反应机理。在煅烧过程中，硝酸镁与氧化铅反应生成铅的活化中间体Pb6O5（NO3）2，由此活化的PbO或Pb3O4可与Nb2O5生成不稳定的、缺B位的焦绿石相Pb3Nb2O8，再与MgO反应生成钙钛矿相PMN－PT。     

Y2O3∶Eu$1纳米晶的尺寸调控与发光性能研究

以尿素为沉淀剂,柠檬酸为表面活性剂,通过水热法得到了非晶态的水合硝酸氧钇前驱体,进一步烧结处理后生成了立方相Y2 O3纳米晶．利用X－射线衍射（ XRD）、扫描电镜（ SEM）、透射电镜（ TEM）、红外光谱（ FTIR）和荧光光谱（ PL）分别对所得样品的相结构、形貌粒度、表面结构以及发光性能进行研究．结果表明：当烧结温度从600℃升高到900℃,Y2 O3∶Eu3＋纳米颗粒的结晶性增强,并实现了粒径调控,由13．0 nm增加至27．9 nm．随着Y2 O3∶Eu3＋纳米颗粒尺寸的增加,比表面积减小会导致发光离子附近的表面晶格缺陷降低,同时纳米晶表面吸附水、硝酸根以及柠檬酸根等杂质离子逐渐被去除,减少了荧光猝灭中心,从而有利于增强荧光发射强度以及延长荧光寿命．     

纳米La2O3／TiO2复合薄膜的制备及光催化性能研究

采用溶胶-凝胶法在陶瓷基体上制备了纳米La2O3／TiO2复合薄膜。利用XRD研究了La2O3不同复合量对纳米TiO2晶型转化的影响，利用SEM研究了Al2O3底膜对La2O3／TiO2复合薄膜形貌的影响，利用亚甲基兰溶液紫外光降解实验研究了La2O3／TiO2复合薄膜的光催化性能．结果表明：复合0．5％（物质的量）La2O3的TiO2干凝胶经850℃煅烧后仍为锐钛矿（64％（质量分数））占主导的混晶结构，平均粒径在10nm左右；当Al2O3底膜和La2O3／TiO2复合薄膜的厚度分别为4层和3层时，经850℃煅烧后，复合薄膜致密且无微裂纹出现，而且具有佳的光催化性能．     

EDTA络合溶胶-凝胶法制备Y2O3:Eu纳米晶

以金属硝酸盐和EDTA为原料，用EDTA络合溶胶-凝胶法制备出Y2O3:Eu纳米晶，并对合成条件进行了优化。分别用TG-DTA、FTIR、XRD、SEM、荧光分光光度计等手段对凝胶的热分解机理、Y2O3:Eu的形成过程以及纳米晶的性质进行了研究。结果表明：硝酸根离子可以加速EDTA凝胶的热分解，仅600℃焙烧即可得到颗粒细小、组分均匀、纯立方相的Y2O3:Eu纳米晶，颗粒基本呈球形，粒径随温度升高逐渐长大，600℃时，约为20nm,1000℃时，约为70nm。     

Al2O3微粉的表面改性及表征

以α—Al2O3微粉为基体，Y(NO3)3溶液为包裹相，采用液相包裹法进行加钇颗粒表面改性。获得了表面均匀包裹Y2O3的α—Al2O3粉体。将此粉体与Al合金复合制备复合材料，复合材料组织更加均匀，对材料进行力学性能测试，结果表明：改性粉体对Al合金增强效果明显增加，抗拉强度提高27．2％，屈服强度提高33．1％，延伸率提高10．3％。     

Annealing process of fine grained co-stabilised (Y,Mg)-PSZ/MgAl2O4 ceramics

Abstract

Co-stabilised (Y,Mg) partially stabilised zirconia (PSZ) ceramics with MgAl₂O₄ spinel additions were produced, with industrial zirconia as the main starting material. Powders were prepared using a mechanical milling–mixing process. The effect of the annealing process on the mechanical properties, phase compositions, and microstructure of fine grained PSZ ceramics was investigated.     

Carbon seal materials with superior mechanical properties and fine-grained structure fabricated by a new process

Carbon seal material was prepared using a new liquid mixing process of the raw materials, which had not only lowered open porosity but also provided excellent mechanical properties, especially higher compressive strength (210 MPa) compared with the material prepared by the conventional method. Scanning electron microscopy (SEM) results show that such material has a fine-grained structure as well as little pore diameter. The influence of the manufacturing procedure of the materials on the performance and microstructure is investigated. In addition, correlations between properties and microstructure are also discussed.     

陶瓷颗粒增强Cr0.5MoNbWTi难熔高熵合金复合材料的制备及其力学性能

难熔高熵合金因其优异的力学性能、高温稳定性和抗氧化性能等,作为高温结构材料具有广阔的应用前景.为了进一步提升材料的力学性能,本研究利用原位反应烧结制备了陶瓷颗粒增强难熔高熵合金复合材料,并探讨了陶瓷增强相的生成机理及其对复合材料力学性能的影响.通过机械合金化制备了含有碳氮氧非金属元素的Cr0.5MoNbWTi过饱和体心...     

Ca3Co4O9 ceramics consolidated by SPS process: Optimisation of mechanical and thermoelectric properties

Ca₃Co₄O₉ (349) thermoelectric (TE) oxide ceramics were successfully prepared by Spark Plasma Sintering process. The effects of the uniaxial pressure (30-100 MPa), the dwell temperature (700-900 °C) and the cooling rate were investigated. Microstructure analyses have revealed strong enhancements of the bulk density as the pressure level and the applied temperature during the SPS process are increased. Mechanical properties were investigated by using instrumented nanoindentation and three point bending tests. Hardness, elastic modulus, strength and fracture toughness were shown to improve drastically and depend on the processing parameters. Thermal expansion measurements reveal a noticeable anisotropy induced by unidirectional hot pressing. The mechanical, thermal and thermoelectric properties were correlated to the microstructure and crystallographic texture of the resulting ceramics.     

Sintering Behavior and Microwave Dielectric Properties of MgTiO3 Ceramics Doped with B2O3 by Sol-Gel Method

The B2O3-doped MgTiO3 powders and ceramics have been prepared by sol-gel method using Mg(NO3)2·6H2O, Ti(C4H9O)4 and H3BO3 as the starting materials. The sintering behavior and microwave dielectric properties of ceramics prepared from powders with different particle sizes were investigated. The gels were calcined at 650, 700, 750, 800, 850 and 900 C and the derived particle sizes of powders were 20-30 nm, 30-40 nm, 40-60 nm, 60-90 nm, 90-120 nm and 120-150 nm, respectively. The nanoparticles with the size of 30-60 nm benefited the sintering process with high surface energy whereas nanoparticles with the size of 20-30 nm damaged the microwave dielectric properties due to the pores in the ceramics. The addition of B2O3 used as a liquid sintering aid reduced the sintering temperature of MgTiO3 ceramic, which was supposed to enter the MgTiO3 lattice and resulted in the formation of (MgTi)2(BO3)O phase. The B2O3-doped MgTiO3 ceramic sintered at 1100 C and prepared from the nanoparticles of 40-60 nm had compact structure and exhibited good microwave dielectric properties: εr=17.63, Q × f=33,768 GHz and τ f= 48×10 6 C 1.     

Preparation, characterization and mechanical performance of dense β-TCP ceramics with/without magnesium substitution

Beta-tricalcium phosphate (beta-TCP) powder was prepared by a two-step process: wet precipitation of apatitic tricalcium phosphate [Ca(9)(HPO(4))(PO(4))(5)(OH)] (beta-TCP 'precursor') and calcination of the precursor at 800 degrees C for 3 h to produce beta-TCP. Magnesium-substituted tricalcium phosphate (beta-TCMP) was produced by adding Mg(NO(3))(2) . 6H(2)O into Ca(NO(3))(2) solution as Mg(2+) source before the precipitation step. The transition temperature from beta-TCP to alpha-TCP increases with the increase of Mg(2+) content in beta-TCMP. beta-TCMP with 3 mol.% Mg(2+) has beta-TCP to alpha-TCP transition temperature above 1,300 degrees C. Dense beta-TCMP (3 mol.% Mg(2+)) ceramics ( approximately 99.4% relative density) were produced by pressing the green bodies at 100 MPa and further sintering at 1,250 degrees C for 2 h. The average compressive strength of dense beta-TCP ceramics sintered at 1,100 degrees C is approximately 540 MPa, while that of beta-TCMP (3 mol.% Mg(2+)) ceramics is approximately 430 MPa.     

Synthesis of new materials by laser pyrolysis: ZrO2, Y2O3:Ce and TiC(x)N(y) nanoparticles

New developments concerning the synthesis of oxide and non oxide nanoparticles by laser pyrolysis are reported here. In order to be able to study the relations between the host and the guest in doped nanostructured luminescent oxide matrix, tetragonal ZrO2 nanoparticles were synthesized with sizes as low as 3 nm in weighable amounts. Y2O3 nanoparticles doped with Ce were also prepared with grains in the 10-20 nm size range. Concerning the non-oxide materials, TiC, TiN, and TiC(x)N(y) nanopowders were obtained from simple annealing treatments performed on TiO2/C nanocomposites grown by laser pyrolysis. The final crystalline phase was controlled by the initial C content and the annealing atmosphere. Once sintered, these materials will allow the study of the mechanical properties of nanostructured carbonitride ceramics.     

Effect of High‐Energy Ball Milling on Mechanical Properties of the Mg–Nb Composites Fabricated through Powder Metallurgy Process

New biocompatible and biodegradable Mg–Nb composites used as bone implant materials are fabricated through powder metallurgy process. Mg–Nb mixture powders are prepared through mechanical milling and manual mixing. Then, the Mg–Nb composites are fabricated through cold press and sintering processes. The effect of mechanical milling and Nb particles as reinforcements on the microstructures and mechanical properties of Mg–Nb composites are investigated. The mechanical milling process is found to be effective in reducing the size of Mg and Nb particles, distributing the Nb particles uniformly in the Mg matrix and obtaining Mg–Nb composite particles. The Mg–Nb composite particles can be bound together firmly during the sintering process, result in Mg–Nb composite structures with no intermetallic formation, lower porosity, and higher mechanical properties compared to composites prepared through manual mixing. Interestingly, the mechanical properties of manually mixed Mg–Nb composites appear to be even lower than that of pure Mg.

     

热等静压烧结制备细晶粒Ce,Y:SrHfO3闪烁陶瓷

Ce:SrHfO₃陶瓷因具有高密度和高有效原子序数, 对高能射线具有很强的阻止能力。同时, Ce:SrHfO₃陶瓷还具有快衰减和高能量分辨率等优异的闪烁性能, 引起了研究人员的广泛关注。由于传统的烧结方法难以实现非立方结构Ce:SrHfO₃陶瓷的透明化, 本研究采用真空长时烧结和短时真空预烧结合热等静压烧结(Hot Isostatic Pressing, HIP)方法制备Ce,Y:SrHfO₃陶瓷。以金属氧化物和碳酸盐为原料, 1200 ℃下煅烧8 h可以获得平均粒径为152 nm的纯相Ce,Y:SrHfO₃粉体。1800 ℃真空烧结20 h获得平均晶粒尺寸为28.6 μm的不透明的Ce,Y:SrHfO₃陶瓷, 而两步烧结法可以制备光学透过率良好的Ce,Y:SrHfO₃陶瓷。本研究详细分析了陶瓷致密化过程中微结构的演变, 探究了预烧结温度对Ce,Y:SrHfO₃陶瓷密度、显微结构和光学透过率的影响。真空预烧(1500 ℃×2 h)结合HIP后处理(1800 ℃×3 h, 200 MPa Ar)所获得的Ce,Y:SrHfO₃陶瓷在800 nm处的最高直线透过率为21.6%, 平均晶粒尺寸仅为3.4 μm。在X射线激发下, Ce,Y:SrHfO₃陶瓷在400 nm处产生Ce³⁺ 5d-4f发射峰, 其XEL积分强度比商用锗酸铋(BGO)晶体高3.3倍, Ce,Y:SrHfO₃陶瓷在1 μs门宽下的光产额约为3700 ph/MeV。良好的光学和闪烁性能可以拓宽Ce,Y:SrHfO₃陶瓷在闪烁探测领域的应用。