共查询到20条相似文献,搜索用时 15 毫秒
1.
Christiane L. Ojaimi Julieta A. Ferreira Adilson L. Chinelatto Raphael E. P. Salem Adriana S. A. Chinelatto Eliria M. J. A. Pallone 《International Journal of Applied Ceramic Technology》2020,17(4):1619-1628
Composites of Al2O3/ZrO2 (containing 25, 50, and 75 vol% ZrO2) were prepared by mixing Al2O3 and ZrO2 suspensions. The microstructural control via two-step sintering (TSS) was the main objective of this work. For this purpose, different sintering curves were constructed, aiming to achieve the best temperature combination for the sintering steps that provides higher density and finer microstructure. The results were compared with single-step sintering (SSS). Furthermore, microhardness and fracture toughness were measured for the best TSS specimens under each composition. The results showed that the high densities were obtained, and the reduction of grain size was greater than 40% for two-step sintered specimens, compared to SSS ones. Consequently, microhardness values increased. However, fracture toughness values remained unchanged. 相似文献
2.
Mechanical properties of 1 mol% CeO2‐10 mol% Sc2O3 co‐doped and stabilized ZrO2 synthesized through hydro/solve‐thermal method
下载免费PDF全文
![点击此处可从《International Journal of Applied Ceramic Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yuchen Liu Xiaoyu Chen Rui Yao Songyi Liao Weiping Chen Donghong Nie Yueming Wang Feng Zheng 《International Journal of Applied Ceramic Technology》2017,14(3):474-485
Ultra‐fine 1 mol% CeO2‐10 mol% Sc2O3 co‐doped and stabilized ZrO2 (1Ce10ScSZ) powders with average grain size less than 10 nm in diameter were prepared by hydro/solve‐thermal method using either deionized water, ethanol, or methanol as solvent. As‐synthesized powders were characterized in terms of phase structure, particle morphology, and chemical composition by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), high‐resolution transmission electron microscopy (HRTEM), and inductively coupled plasma‐optical emission spectroscopy (ICP‐OES), respectively. Sintering studying was conducted on pellets of 15 mm in diameter and 3 mm in thickness under uniaxial compaction using 25 MPa at either 600, 800, 1000, 1100, 1200, 1400, or 1500°C for 1 hour. Phase transitions and grain morphologies of those sintered samples were characterized by XRD and field emission scanning electron microscopy (FESEM). Mechanical properties were characterized on dense pellets sintered at 1500°C by nanoindentation. Experimental results showed that ethanol was more effective to synthesize agglomerate‐free 1Ce10ScSZ powders as compared with deionized water and methanol. Choice of solvent affected the environment of hydro/solve‐thermal solution, which led to variation of chemical compositions of powders and porosities of sintered pellets, and therefore, influenced their mechanical performance. Our study showed that solvent was important to make dense, thin, and mechanically robust 1Ce10ScSZ electrolyte for potential applications in electrochemical devices. Absolute values of hardness (H) and Young's modulus (E) measured from our samples are much higher and more consistence than those results obtained from commercial vendors reported in literatures. 相似文献
3.
液相沉淀法制备ZrO2/Al2O3纳米复合粉体 总被引:5,自引:0,他引:5
以NH4Al(SO4)2·12H2O,ZrOCl2·8H2O,Y(NO)3为原材料,用NH4HCO3作沉淀剂,控制滴定速度小于5 mL/min,采用液相沉淀法制备了超细3Y-ZrO2/Al2O3前驱体.前驱体为分散的碱式碳酸盐,在1 200℃煅烧得到了分散性良好,平均粒径为20 nm的t-ZrO2和α-Al2O3两相分布均匀的纳米复合粉体.X射线衍射分析显示前驱体在煅烧过程中无中间相γ-Al2O3,θ-Al2O3生成.所制备的粉体具有高的烧结活性.在1 450℃烧结后烧结体相对致密度可达97.4%. 相似文献
4.
Properties and microstructural aspects of TiO2‐doped sintered Alumina‐Zirconia composite ceramics
下载免费PDF全文
![点击此处可从《International Journal of Applied Ceramic Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Amani Khaskhoussi Hazem Bouhamed Luigi Calabrese Edoardo Proverbio Jamel Bouaziz 《International Journal of Applied Ceramic Technology》2018,15(6):1532-1541
The effect of titania content on the densification, the phase transformation, the microstructures, and mechanical properties of 50 wt% Al2O3‐50 wt% ZrO2 (12 mol% CeO2) was evaluated. Ceramic composites with different TiO2 content (0.27, 5, 10 wt%) were prepared by pressureless sintering at low temperature (1400°C) for 2 hours in air. Dense ceramic was obtained by adding 5 wt% of TiO2 loading to improved mechanical properties. The microstructure analysis provided lots of information about solid‐state reactivity in alumina‐zirconia‐titania ternary system. The content of TiO2 strongly affected the phases evolution and the grain growth during sintering. Furthermore, a significant effect on mechanical properties and fracture behavior was also observed. 相似文献
5.
Al2O3-ZrO2陶瓷体系中晶粒生长模型的研究 总被引:9,自引:2,他引:9
研究了Al2O3-ZrO2陶瓷体系中两相晶粒生长,提出了双相体系的晶粒生长模型,并解释了“内晶型”结构是如何形成的。研究发现,两相结构的形成与温度、保温时间及ZrO2等二相的数量有关系,其中温度的影响最为显著。内晶型ZrO2结构的形成是基体晶粒急剧长大的结果,而不是以往研究的以纳米粒子为生长点,基体粒子的成核、长大。有利于基体晶粒急剧生长的条件也有利于内晶的形成;内晶的形成过程可概括为Ostwald生长与基体晶粒的快速长大。但值得注意的是,并不是ZrO2的含量越多,形成的内晶型结构就越多。 相似文献
6.
Giulio Malucelli Paola Palmero Silvia Ronchetti Alessandro Delmastro Laura Montanaro 《Polymer International》2010,59(8):1084-1089
Two different alumina powders were dispersed in low‐density polyethylene (LDPE) to evaluate if any role can be ascribed to the crystalline phase, size and morphology of the alumina filler. In particular a submicrometric α‐alumina and a nanocrystalline transition (γ/δ) alumina were added to the polymer at 5 wt% concentration, using a Brabender mixing unit. Both the neat inorganic fillers showed a good dispersibility in the polyolefin. The thermal and mechanical properties of the composites obtained were evaluated. As expected, a significant increase of the stiffness and abrasion resistance of LDPE was achieved in both cases. Furthermore, the composites showed a higher thermo‐oxidative stability with respect to neat LDPE. Independent of their crystalline phase, size and morphology, both fillers gave a similar enhancement of composite features. Copyright © 2010 Society of Chemical Industry 相似文献
7.
Lei Liu Kensaku Maeda Tetsuhiko Onda Zhong-Chun Chen 《Journal of the European Ceramic Society》2018,38(15):5113-5121
Al2O3/Ba-β-Al2O3/ZrO2 composites were fabricated by solid-state reaction sintering of Al2O3, BaZrO3, and yttria stabilized zirconia (YSZ) powders. The effects of YSZ addition on microstructure and mechanical properties have been investigated. The incorporation of YSZ promoted the densification of the composites and formation of tetragonal ZrO2 phase. The microstructure of the composites was characterized by elongated Ba-β-Al2O3 phase and equiaxed ZrO2 particles including added YSZ and reaction-formed ZrO2. The Al2O3/Ba-β-Al2O3/ZrO2 composites with YSZ addition exhibited improved fracture toughness, as a result of multiple toughening effects including crack deflection, crack bridging, crack branching, and martensitic transformation of ZrO2 formed by the reactions between Al2O3 and BaZrO3. Moreover, owing to the grain refinement of Al2O3 matrix, dispersion strengthening of the added YSZ particles, and an increase in density of the composites, the Vickers hardness and flexural strength of Al2O3/Ba-β-Al2O3/ZrO2 composites were dramatically enhanced in comparison with the composites without YSZ addition. 相似文献
8.
9.
Muhammad Waqas Khalid SangCheol Park InYeong Kim Javid Hussain Amjad Hussain Ammad Ali Bum Sung Kim Bin Lee 《Journal of the American Ceramic Society》2023,106(12):7288-7302
In this study, microwave hybrid sintering and conventional sintering of Al2O3- and Al2O3/ZrO2-laminated structures fabricated via aqueous tape casting were investigated. A combination of process temperature control rings and thermocouples was used to measure the sample surface temperatures more accurately. Microwave hybrid sintering caused higher densification and resulted in higher hardness in Al2O3 and Al2O3/ZrO2 than in their conventionally sintered counterparts. The flexural strength of microwave-hybrid-sintered Al2O3/ZrO2 was 70.9% higher than that of the conventionally sintered composite, despite a lower sintering temperature. The fracture toughness of the microwave-hybrid-sintered Al2O3 increased remarkably by 107.8% despite a decrease in the relative density when only 3 wt.% t-ZrO2 was added. The fracture toughness of the microwave-hybrid-sintered Al2O3/ZrO2 was significantly higher (247.7%) than that of the conventionally sintered composite. A higher particle coordination and voids elimination due to the tape casting and the lamination processes, the microwave effect, the stress-induced martensitic phase transformation, and the grain refinement phenomenon are regarded as the main reasons for the mentioned outcomes. 相似文献
10.
Jonathan D. French Helcn M. Chan Martin P. Harmer Gary A. Miller 《Journal of the American Ceramic Society》1992,75(2):418-423
Composites of Al2 O3 (A) and cubic ZrO2 (Z) (8 mol% Y2 O3 ) (with c -ZrO2 volume fractions ranging from O to 1) were fabricated by pressureless sintering of mechanically mixed powders. The microstructures of the AZ composites were duplex, with the grains of both phases exhibiting similar size. Room-temperature mechanical properties including Young's modulus (determined from elastic wave velocity measurements), strength and toughness (by indentation-strength-in-bending), and Vickers microhardness were evaluated for the full range of compositions. All properties exhibited a linear decrease with increasing c -ZrO2 content, and no R -curve behavior was seen in any of the composite compositions. Fracture morphology, observed from cracks emanating from microhardness indentations, changed from essentially intergranular for the tougher Al2 O3 to transgranular for c -ZrO2 , with AZ composites exhibiting mixed morphology. 相似文献
11.
Shengfang Shi Sunghun Cho Tomoyo Goto Tohru Sekino 《Journal of the American Ceramic Society》2018,101(7):3181-3190
Al2O3/Ti composites containing 0‐30 vol% dispersed fine Ti particles were fabricated using a hot‐press sintering method at 1500°C from mixtures of Al2O3 and TiH2 powders. During sintering, TiH2 decomposed to form metallic Ti. The effects of the Ti content on the mechanical and electrical properties of the composites were then investigated. No Ti‐Al intermetallic compounds were detected by X‐ray diffraction, and energy‐dispersive X‐ray spectroscopy indicated the presence of Al‐Ti‐O solid solution and Ti‐O phases. The composites showed enhanced densification; the measured densities were higher than the calculated theoretical values. Microstructural observation revealed homogeneously distributed fine Ti particles dispersed in the Al2O3 matrix. The Ti particle size ranged from submicrometer to a few micrometers depending on the Ti content. The fracture mode of the composites was primarily transgranular, in contrast to the intergranular fracture mode of monolithic Al2O3. Although the flexural strength was decreased with increase in Ti content, the composite containing 20 vol% Ti displayed the maximum fracture toughness of 4.3 MPa·cm1/2, which was 37% greater than that of monolithic Al2O3. The composites containing more than 15 vol% Ti exhibited drastic decreases in resistivity (~10?1 Ωcm), which were attributed to the formation of interconnected Ti networks at these Ti contents. The percolation threshold volume for electrical conduction in the present system was calculated to be 13.8 vol%. The results indicate that dispersing fine Ti particles into Al2O3 increased the fracture toughness and improved the conductivity of Al2O3. 相似文献
12.
13.
Shengfang Shi Sunghun Cho Tomoyo Goto Tohru Sekino 《International Journal of Applied Ceramic Technology》2021,18(1):170-181
This work discusses the reinforcement effect of elongated CeAl11O18 phase on multifunctional Al2O3/Ti composites by adding CeO2 to inhibit interfacial reaction and strengthen interface for inducing optimized performances. For this purpose, Al2O3/Ti composite with different contents of CeO2 was fabricated and the microstructure, mechanical and electrical properties were studied. Results indicated that after CeO2 was added, elongated CeAl11O18 phase was formed within these composites. Owing to inhibited interfacial reaction between Al2O3 and Ti, Ti content was increased and compositions of composites were calculated using Rietveld method based on X-ray diffraction patterns. Attributed to the strengthening and toughening effects of CeAl11O18 phase, 2 mol% CeO2 added composite showed the highest flexural strength and fracture toughness of 576 MPa and 5.15 MPa·m1/2, which increased by 21% and 20% compared to Al2O3/Ti composite without CeO2 addition. In this case, crack bridging by both Ti and CeAl11O18 particles was the major toughening mechanism and the additional fracture toughness caused by CeAl11O18 toughening effect reached a maximum. The role (crack bridging or particle pull-out mechanism) of CeAl11O18 in toughening Al2O3/Ti composites depended on the aspect ratio of these elongated particles, which was directly related to CeO2 content. Because of the inhibition of interfacial reaction and the increase in Ti content, excellent electrical resistivity of composites after CeO2 addition was maintained in spite of the formation of insulated CeAl11O18 phase. All samples showed relatively low electrical resistivity of ~10−3 Ωcm. 相似文献
14.
Yoshihiko Takano Masaru Yoshinaka Ken Hirota Osamu Yamaguchi 《Journal of the American Ceramic Society》2001,84(10):2445-2447
Intermetallic CoAl powder has been prepared via self-propagating high-temperature synthesis (SHS). Dense CoAl materials (99.6% of theoretical) with the combined additions of ZrO2 (3Y) and Al2 O3 have been fabricated via spark plasma sintering (SPS) for 10 min at 1300°C and 30 MPa. The microstructures are such that tetragonal ZrO2 (0.3 μm) and Al2 O3 (0.5 μm) particles are located at the grain boundaries of the CoAl (8.5 μm) matrix. Improved mechanical properties are obtained; especially the fracture toughness and the bending strength of the materials with ZrO2 (3Y)/Al2 O3 = 16/4 mol% are 3.87 MPa·m1/2 and 1080 MPa, respectively, and high strength (>600 MPa) can be retained up to 1000°C. 相似文献
15.
本研究以耐磨结构陶瓷的应用为目标,研究了Al2O3-ZrO2复相陶瓷中加入不同的ZrO2陶瓷材料对微观结构及其力学性能的影响,分析了ZrO2在复相陶瓷中所起的作用.结果表明:随ZrO2含量的增加,在相同烧结温度下,晶粒变小,材料的力学性能提高.当ZrO2加入量为55%时,复相材料的抗折强度503MPa,断裂韧性12.80 MPa·m1/2,密度4.88 g·cm-3,硬度(HV)为1432 kg ·mm-2.探讨了Al2O3/ZrO2复相陶瓷的增韧机理. 相似文献
16.
High catalytic efficiency in liquid‐phase oxidation of 1,4‐dioxane using a Pt/CeO2‐ZrO2‐SnO2/SBA‐16 catalyst
下载免费PDF全文
![点击此处可从《International Journal of Applied Ceramic Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Pil‐Gyu Choi Naoyoshi Nunotani Nobuhito Imanaka 《International Journal of Applied Ceramic Technology》2017,14(1):9-15
A Pt/CeO2–ZrO2–SnO2/SBA‐16 (SBA‐16: Santa Barbara Amorphous No. 16) catalyst was developed for the efficient removal of 1,4‐dioxane. Because the catalyst showed synergistic action between the high catalytic activity of Pt and the high oxygen release and storage abilities of CeO2–ZrO2–SnO2, high catalytic efficiency in the liquid phase was obtained in an air atmosphere without the supply of any strongly oxidizing additives or photoirradiation. After reaction at 80°C for 4 h, the residual percentage of 1,4‐dioxane reached 31%. Furthermore, the Pt/CeO2–ZrO2–SnO2/SBA‐16 catalyst exhibited high reusability and durability and the rate of net decrease in 1,4‐dioxane reached 44% at 80°C. 相似文献
17.
Xiang Yang Zhang Wen Chen Kun Li Yong-kang Peng Zhi-hang Sun Chen-cheng Wu Wen-jun Cao Jian-hui 《International Journal of Applied Ceramic Technology》2022,19(6):3267-3278
Continuous alumina fiber–reinforced alumina matrix composites (Al2O3f/Al2O3 composites) were produced via sol–gel process, then the high-temperature mechanical property and thermal shock resistance of Al2O3f/Al2O3 composites were investigated. The results showed that the composites exhibited excellent high-temperature properties. The mechanical property of the composites was affected by heat treatment (prepared at 1100°C exhibited the most desirable mechanical property). The tensile strength of the composites abruptly decreased at higher temperatures. Although the mechanical property of the composites deteriorated after the thermal shock test was conducted at high temperatures, they exhibited excellent thermal shock resistance. After 50 thermal shock tests conducted at 1300 and 1500°C, the flexural strength of the composites was found to be 124.34 and 93.04 MPa, thus showing a decrease in strength with the increasing temperature. 相似文献
18.
19.
针对5Y-ZrO2/Al2O3复相陶瓷出现的晶粒异常长大和晶粒开裂问题展开研究。以ZrO2和Al2O3为主要原料,采用常压烧结工艺制备陶瓷样品,利用SEM观察显微组织。分析表明:MgO对抑制Al2O3晶粒异常长大有重要影响,MgO的加入量应随着Al2O3加入量的变化而改变;烧结温度的改变将导致异常长大的Al2O3晶粒细化。当烧结温度较低时,Al2O3晶粒将在短轴方向逐渐断开成段;当温度较高时,则沿着长轴方向逐渐开裂成条状。ZrO2晶粒的断裂主要与烧结温度有关:在1630℃以上烧结时,出现裂纹并贯穿晶粒;晶粒开裂的原因是:烧结温度较高时,陶瓷中形成了t-ZrO2,在降温过程中大颗粒的t相发生t→m相变,而小颗粒t相则无法变成m相,引起局部体积变化不均匀,从而产生相变应力导致晶粒穿晶断裂。 相似文献
20.
Fei Zuo Fan Meng Dong-Tao Lin Jun-Jie Yu Hong-Jian Wang Shen Xu Wei-Ming Guo Carmen Cerecedo Víctor Valcárcel Hua-Tay Lin 《Journal of the European Ceramic Society》2018,38(4):1796-1801
A novel composite of 12 mol% CeO2-stablized tetragonal ZrO2 reinforced with Al2O3 whiskers (designated as Ce-TZP/Aw) has been prepared and studied in this work. The objective of this investigation was to systematically study the influence of whisker-aspect-ratio on the densification behaviors, microstructure evolution, and mechanical properties of Ce-TZP/Aw composite. Results showed that the sintered density of composite increased and the grain growth tended to diminish with the decrease in whisker aspect radio. Both the fracture toughness and flexural strength reached maximum values of 475 ± 12 MPa and 11.4 ± 0.2 MPa m1/2, respectively at a whisker aspect ratio of about 12. It was also observed that the fracture toughness, flexural strength and tetragonal to monoclinic ZrO2 transformation of the dual-phase composite exhibited similar variation trend as a function of the whisker-aspect-ratio, which suggested that the stress-induced phase transformation should be the main toughening and strengthening mechanism in the Ce-TZP/Aw composite. 相似文献