ZrO2纳米颗粒的添加对ZrO2/HA复合陶瓷物相和力学性能的影响

将液相掺杂CeO2和Fe2O3的钇稳定四方ZrO2纳米粉作为着色剂添加到微米ZrO2/HA体系中,1400℃烧结制备了ZrO2/HA纳米复合陶瓷.利用X射线衍射分析了复合陶瓷的物相组成;三点弯曲法、单边切口梁法及压痕法测试了陶瓷的力学性能;讨论了纳米氧化锆的添加对复合陶瓷力学性能及物相组成的影响,分析纳米氧化锆导致复合陶瓷力学性能改变的原因.根据复合陶瓷断裂前后单斜相氧化锆的含量变化,证实氧化锆纳米粉的添加不仅有利于复合陶瓷中四方相氧化锆的稳定存在,而且可以提高基体相变四方相氧化锆的含量,相变增韧作用加强.力学性能测试结果显示:体系中适量纳米氧化锆的存在可以提高材料的抗弯强度和断裂韧性20%以上,密度和硬度少量增加,但由于没有新物相引入,对弹性模量未造成影响.     

铬精矿细粉添加量对铜冶炼炉用铝铬材料性能的影响

为了充分利用铝铬渣资源,并提高铜冶炼炉用铝铬材料的性能,以铝铬渣制备的铬刚玉、铬精矿细粉、部分稳定氧化锆微粉、Cr_2O_3粉和α-Al_2O_3微粉为主要原料,以磷酸二氢铝为结合剂,研究了铬精矿细粉添加量(加入质量分数分别为10%、15%、20%、25%和29%)对试样经1 600℃保温3 h烧后的显微结构、物相组成、常温性能及抗渣性能的影响。结果表明:随着铬精矿细粉加入量的增加,试样的致密度增大,常温力学性能呈现先增加后降低的趋势;铬精矿的加入增加了试样中的铬含量,从而提高了铝铬固溶体的含量,在炉衬和熔渣接触面上生成的高熔点铁铬尖晶石或铁铝尖晶石,黏附在炉衬上形成保护层,提高铬刚玉砖的抗渣性能。加入25%(w)铬精矿时,试样的综合性能最佳。     

非均匀沉淀法制备黑色氧化锆陶瓷

以Y-TZP（氧化钇稳定四方多晶氧化锆）为原料、硝酸锰和硝酸铝为着色剂、PEG2000（聚乙二醇2000）为分散剂,采用非均匀沉淀法制备着色剂/氧化锆复合粉体,经成型、烧结后得到黑色氧化锆陶瓷。采用X射线衍射,扫描电子显微镜、X射线荧光分析和透射电子显微镜等对复合粉体和陶瓷的结构和性能进行表征,结果表明：着色剂/氧化锆...     

以活性炭粉为造孔剂制备多孔YSZ陶瓷

采用氧化锆为基体、活性炭粉为造孔剂及氧化钇作为稳定剂来制备多孔YSZ陶瓷。通过TG-DTA分析制定出多孔YSZ陶瓷的烧结制度,研究了造孔剂的加入量和烧结温度对多孔YSZ陶瓷力学性能的影响。并利用阿基米德排水法、万能试验机、显微硬度仪、XRD及SEM对多孔YSZ陶瓷的气孔率、硬度、弯曲强度、物相组成及微观结构等进行分析。结果表明:试样主要以t-ZrO_2存在,有少许的m-ZrO_2相,说明烧结后的试样基本转化为了稳定的t相二氧化锆;SEM图观察发现,陶瓷孔洞分布均匀且大小接近,孔的数量也比较多;随着造孔剂加入量的逐渐增加,多孔陶瓷试样的气孔率逐渐增加而强度下降,同时烧结温度影响多孔陶瓷的力学性能。     

烧结温度对3Y-TZP陶瓷结构与力学性能的影响

以Y2O3为稳定剂,通过无压烧结制备了3mol%钇稳定氧化锆(3Y-TZP)陶瓷,研究了Y2O3不同加入方式、烧结温度对材料相变、显微结构和力学性能的影响.实验结果表明,Y2O3以化学法加入得到的材料中可相变四方相含量高,随温度升高材料致密化程度不断增加,1500℃烧结所得的材料具有最佳的力学性能.     

氧化铈（CeO2）在增韧陶瓷材料中的应用

本研究以氧化铈作稳定剂，采用粉末冶金冷压烧结工艺制备氧化铈部分稳定化氧化锆增韧氧化铝陶瓷复合材料（Ｃｅ－ＺＴＡ），分析了材质的力学性能和显微结构。结果表明，ＣｅＯ２对四方相氧化锆具有稳定作用，当ＣｅＯ２含量为１０￣１２ｍｏｌ％时，如果晶粒尺寸达４￣５ｕｍ，则Ｃｅ－ＺＴＡ复合材料的韧性和强度均能最大程度地提高。     

烧结工艺对β-氮化硅陶瓷的影响

以β-Si3N4粉末为原料,以YAG（钇铝石榴石）为烧结助剂,通过气氛压力烧结（GPS）制备出致密的β-氮化硅陶瓷材料,形成大小均匀的柱状颗粒和小球状颗粒复合显微结构,研究了烧结助剂质量分数、烧结温度以及保温时间对β-氮化硅陶瓷致密化程度及力学性能的影响.     

Al2O3在莫来石中固溶对ZTM/Al2O3陶瓷结构与性能的影响

研究了加入氧化铝对ZTM陶瓷结构和性能的影响.发现在烧结过程,氧化铝可固溶于莫来石颗粒形成富铝型柱状莫来石,并因其产生的体积膨胀增强了基质对氧化锆颗粒的约束,使材料中的四方氧化锆相对含量增加,其强韧化效果进一步发挥,明显改善了材料的力学性能.     

ZrB_2-YAG陶瓷的烧结致密化

通过共沉淀法获得包覆式Al2O3-Y2O3/ZrB2复合粉体,对其进行放电等离子烧结以提高ZxB2陶瓷的烧结致密度.用扫描电镜观察试样的显微结构,用X射线衍射仪对试样进行物相分析.结果表明:包覆犁粉体在700～1 000℃时出现1次大的收缩,然后出现1个不收缩的平台,当温度达到1 100℃之后出现第2次收缩.适宜制备高致密的ZrB2-钇铝石榴石(yttrium aluminium garnet,YAG)陶瓷的工艺条件为;烧结温度为1 700℃,烧结压力为20MPa,保温时间为4min,YAG的添加量为30%(质量分数),所制备的ZrB2-YAG陶瓷相对密度大于95%.     

添加TiO_2、ZrO_2对烧结铝铬渣材料性能的影响

为了进一步提高酸洗后铝铬渣烧结块的性能尤其是其抗热震性,取粒度≤0.045 mm的铝铬渣,在浓盐酸中煮沸20 min后,过滤,洗净,干燥,制成酸洗铝铬渣。在酸洗铝铬渣中分别加入4%(w)的钛白粉、锆英石粉或钛白粉-锆英石粉复合粉(钛白粉与锆英石粉的质量比为1 1),经混练、成型、干燥后,在1 500℃保温2 h热处理制成烧结铝铬渣试样,然后检测其体积密度、显气孔率、常温耐压强度、常温抗折强度和抗热震性,并分析其显微结构。结果表明:在酸洗铝铬渣中分别添加钛白粉、锆英石粉或复合添加钛白粉-锆英石粉均可提高烧结铝铬渣试样的致密度、常温强度和抗热震性,其中,添加钛白粉-锆英石粉试样的综合性能提高幅度最大。     

Microstructure and mechanical properties of ZrO2-2 mol% Y2O3 ceramics

The microstructure and mechanical properties of ZrO₂-2 mol% Y₂O₃ ceramics were studied on samples prepared by cold isostatic pressing and pressureless sintering. It was shown that the density of the alloy increases with increasing sintering temperature. The Vickers hardness decreases with the appearance of the monoclinic phase and increasing its content. Compared with the single tetragonal phase, the (t + m) dual-phase structure with microcracks has a much higher fracture toughness (16·5 MPa√m) because of a complex mechanism of toughening (transformation, microcracks and residual stresses).     

Effects of added aluminum chromium slag on the structure and mechanical properties of colored zirconia ceramics

Colored zirconia ceramic samples were prepared via pressureless sintering with yttria-stabilized zirconia as a raw material and aluminum chromium slag (ACS) as an additive. Then, the effects of added ACS (0-15.0 wt%) on the microstructure, phase composition, and mechanical properties of the ceramic were investigated. The addition of ACS changed the apparent color of zirconia ceramics from white to pink, and the color deepened as the ACS content increased. In addition, more pores appeared in the sintered ceramic substrate as the content of ACS increased, and the relative density of samples declined from 97.7% to 91.1% with an increase in ACS content. However, the microhardness and bending strength each reached their maximum values (1887.2 HV and 433.5 MPa, respectively) when the content of ACS was 5.0 wt%. Fracture surface analysis of the samples showed that intergranular fractures were the main features of sintered samples with no added ACS, whereas numerous transgranular fractures occurred in sintered samples to which ACS had been added. The XRD results revealed that the prepared mainly composite ceramics were composed of t-ZrO₂, m-ZrO₂, and chromium-corundum, and the content of the t-ZrO₂ gradually increased as the ACS content increased.     

Yb2O3 and Y2O3 co-doped zirconia ceramics

A suspension stabilizer-coating technique was employed to prepare x mol% Yb₂O₃ (x = 1.0, 2.0, 3.0 and 4.0) and 1.0 mol% Y₂O₃ co-doped ZrO₂ powder. A systematic study was conducted on the sintering behaviour, phase assemblage, microstructural development and mechanical properties of Yb₂O₃ and Y₂O₃ co-doped zirconia ceramics. Fully dense ZrO₂ ceramics were obtained by means of pressureless sintering in air for 1 h at 1450 °C. The phase composition of the ceramics could be controlled by tuning the Yb₂O₃ content and the sintering parameters. Polycrystalline tetragonal ZrO₂ (TZP) and fully stabilised cubic ZrO₂ (FSZ) were achieved in the 1.0 mol% Y₂O₃ stabilised ceramic, co-doped with 1.0 mol% Yb₂O₃ and 4.0 mol% Yb₂O₃, respectively. The amount of stabilizer needed to form cubic ZrO₂ phase in the Yb₂O₃ and Y₂O₃ co-doped ZrO₂ ceramics was lower than that of single phase Y₂O₃-doped materials. The indentation fracture toughness could be tailored up to 8.5 MPa m^1/2 in combination with a hardness of 12 GPa by sintering a 1.0 mol% Yb₂O₃ and 1.0 mol% Y₂O₃ ceramic at 1450 °C for 1 h.     

氧化锆对低品位菱镁矿制备镁橄榄石的影响

以低品位菱镁矿与天然硅石为原料,以氧化锆为添加剂,通过固相反应烧结制备镁橄榄石。研究讨论了氧化锆对镁橄榄石材料相组成、晶胞参数、微观结构及常温性能的影响。用X射线衍射（XRD）和扫描电镜（SEM）对烧后试样的相组成和显微结构进行研究。利用X′ Pert plus软件对试样中镁橄榄石相的晶胞参数进行计算。结果表明：加入适量氧化锆可以促进低品位菱镁矿轻烧氧化镁粉与天然硅石通过固相反应烧结合成制备镁橄榄石。锆离子的置换作用导致镁橄榄石相的晶胞参数和晶胞体积减小。氧化锆加入质量分数为1.2%时,镁橄榄石综合性能最好,其密度为1.87 g/cm³,显气孔率为35.1%,吸水率为18.7 %,常温耐压强度为17.9 MPa。     

热处理温度对ZrO2纤维复合ZrO2-C材料性能的影响

浸入式水口是钢铁连铸工序中关键的功能耐火材料,其中以渣线部位的工作环境最为恶劣。目前,最适合的渣线材料是ZrO₂-C材料。为了提高浸入式水口的性能,本文以氧化锆与鳞片石墨为主要原料,添加增强材料氧化锆纤维及金属硅粉等,以酚醛树脂为结合剂制备ZrO₂-C复合材料。比较了1 000 ℃、1 200 ℃和1 500 ℃三种热处理温度对ZrO₂-C材料的性能及显微结构的影响,结果表明,在热处理温度高于1 200 ℃时,ZrO₂-C材料中的硅粉与石墨发生反应生成碳化硅,大量晶须状碳化硅与ZrO₂纤维交错在一起形成网络结构,提高了材料的力学性能和抗热震性。     

Thermal evolution and crystallisation of polydimethylsiloxane–zirconia nanocomposites prepared by the sol–gel method

Polydimethylsiloxane–zirconia nanocomposites have been prepared by hydrolysis of diethoxydimethylsilane and zirconium n-propoxide in different molar ratios. Transparent, homogeneous and non-porous xerogels have been obtained up to 70 mol% ZrO₂ content. The starting xerogels have been pyrolyzed under argon atmosphere up to 1400°C and the structural evolution of samples treated at different temperatures has been followed by X-ray diffraction, transmission electron microscopy, infrared and ²⁹Si solid state nuclear magnetic resonance spectroscopies, thermal analyses and N₂ sorption measurements. The polymer-to-ceramic conversion leads to the structural rearrangement of the siloxane component with the production at 600°C of high surface area materials with pore sizes below 3 nm. Samples are amorphous up to 800°C. At 1000°C, the structural evolution of the silicon moiety produces an amorphous oxycarbide phase whereas the primary crystallisation of tetragonal zirconia takes place, with crystallinity and crystallite sizes depending on the ZrO₂ content. At 1400°C, the silicon oxycarbide phase generates a mixture of amorphous silica and crystalline silicon carbide polymorphs. In this matrix, tetragonal and monoclinic ZrO₂ phases are present with ZrO₂ average crystallite dimensions never exceeding 20 nm, for ZrO₂ content ≤50 mol%. The tetragonal/monoclinic ratio as well as the crystallite sizes appear strictly related to the chemical composition. ©     

Y2O3-CeO2-doped ZrO2 ceramics from coprecipitated oxalate precursors

Y₂O₃-CeO₂-doped ZrO₂ ceramics were prepared from coprecipitated oxalate precursor material. The thermal decomposition behaviour of the oxalates was studied to find proper conditions for conversion to the oxides. The properties of the calcined oxide powders were measured and sintering conditions to prepare ceramic specimen were investigated. The mechanical properties of the sintered bodies are reported and their relations to composition and sintering conditions will be discussed.     

Ce-Y(Ca)-TZP陶瓷及Ce-TZP/Al2O3复相陶瓷的研究与应用进展

氧化铈稳定的四方氧化锆多晶陶瓷(Ce-TZP)具有良好的抗低温老化性和很高的断裂韧性(K_IC>20 MPa·m^1/2),但是弯曲强度较低(500 MPa左右)。如何在保留Ce-TZP陶瓷的抗低温老化性和高断裂韧性的同时,提高其强度,是本领域研究人员共同关心的问题。大量研究表明,通过添加其他固溶离子(如Y³⁺)达到共稳定效果和引入第二相(如Al₂O₃)获得细晶Ce-TZP基的复相陶瓷,可以显著提高材料的断裂强度,综合改善其力学性能。本文对CeO₂与其他氧化物共稳定的ZrO₂陶瓷及Ce-TZP/Al₂O₃复相陶瓷的研究进展进行了综述,并以义齿种植和增材制造为例介绍了其应用现状。     

Microstructural development of sintered ZrO2---CeO2 ceramics

Microstructural development associated with diffusionless phase transformation was investigated in sintered ZrO₂-10–60 mol% CeO₂ ceramics cooled rapidly from a high temperature, using TEM and XRD techniques. The results show that (112) reflections appeared and a domain structure was found in ZrO₂-20–40 mol% CeO₂ samples, which is a result of c-t′ diffusionless transition, while the structure of the ZrO₂-60 mol% CeO₂ sample was fully stabilized zirconia, in which no forbidden reflections of c-ZrO₂ appeared. Finally, plate martensite and lath martensite structure were found in the ZrO₂-10 mol% CeO₂ sample; the former is the tetragonal phase with internal twins and the latter is the twinned monoclinic phase.     

Low-Temperature Processing and Mechanical Properties of Zirconia and Zirconia–Alumina Nanoceramics

The 1.5- to 3-mol%-Y₂O₃-stabilized tetragonal ZrO₂ (Y-TZP) and Al₂O₃/Y-TZP nanocomposite ceramics with 1 to 5 wt% of alumina were produced by a colloidal technique and low-temperature sintering. The influence of the ceramic processing conditions, resulting density, microstructure, and the alumina content on the hardness and toughness were determined. The densification of the zirconia (Y-TZP) ceramic at low temperatures was possible only when a highly uniform packing of the nanoaggregates was achieved in the green compacts. The bulk nanostructured 3-mol%-yttria-stabilized zirconia ceramic with an average grain size of 112 nm was shown to reach a hardness of 12.2 GPa and a fracture toughness of 9.3 MPa·m^1/2. The addition of alumina allowed the sintering process to be intensified. A nanograined bulk alumina/zirconia composite ceramic with an average grain size of 94 nm was obtained, and the hardness increased to 16.2 GPa. Nanograined tetragonal zirconia ceramics with a reduced yttria-stabilizer content were shown to reach fracture toughnesses between 12.6–14.8 MPa·m^1/2 (2Y-TZP) and 11.9–13.9 MPa·m^1/2 (1.5Y-TZP).