Effects of β-Si3N4 Seeds Addition on Microstructure and Mechanical Properties of Porous Si3N4 Ceramics

2012 ◽  
Vol 724 ◽  
pp. 201-204 ◽  
Author(s):  
Fang Li Yu ◽  
Yu Bai ◽  
Jun Du ◽  
Ping Ping Yu ◽  
Jian Zhi Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Flexural Strength ◽  
Porous Si ◽  
Three Point Bending ◽  
Average Aspect Ratio ◽  
Conventional Sintering ◽  
Porous Microstructure ◽  
Sintering Method ◽  
Scanning Electron

Porous Si3N4 ceramics were prepared by conventional sintering method with the initial Si3N4 powder added different amounts of β-Si3N4 seeds and 5 wt.% Y2O3. The porosity, density and flexural strength were tested by Archimedes and three-point bending methods, respectively. Microstructure of porous Si3N4 ceramics was studied by scanning electron microscopy. The results showed that the fibrous β-Si3N4 grains developed in the bimodal porous microstructure and the average aspect ratio of 6.42 by adjusting the β-Si3N4 seeds content up to 3 wt.%. Under the porosity of about 42%, the flexural strength of the materials could reached 315.98 MPa.

Study on Microstructure and Mechanical Properties of Porous Si3N4 Ceramics

2012 ◽  
Vol 724 ◽  
pp. 241-244 ◽  
Author(s):  
Fang Li Yu ◽  
Yu Bai ◽  
Jun Du ◽  
Ping Ping Yu ◽  
Jian Zhi Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
Flexural Strength ◽  
Porous Si ◽  
Sintering Additives ◽  
Microstructure And Mechanical Properties ◽  
Average Aspect Ratio ◽  
Porous Microstructure ◽  
Porosity Range ◽  
Better Than

Porous Si3N4 ceramics were fabricated by using different species β-Si3N4 as seeds, 5 wt.% Y2O3 and Lu2O3 as sintering additives. Effects of three types of β-Si3N4 seeds and two types of sintering additives on the microstructure and mechanical properties of porous Si3N4 ceramics were investigated. The results showed rod-like β-Si3N4 grains with finer and high aspect ratio developed in the porous microstructure. The microstructure and mechanical properties of specimens added with Lu2O3 and β-Si3N4 seeds were better than which of those added with Y2O3 and β-Si3N4 powder. The flexural strength and average aspect ratio of porous Si3N4 ceramics were in the range of 297349 MPa and 5.757.26 with the porosity range of 41.07%44.40%.

Effect of Sintering Temperature on Microstructure and Mechanical Properties of Al2O3-TiC-ZrO2 Ceramic Composites

2012 ◽  
Vol 476-478 ◽  
pp. 1031-1035
Author(s):  
Wei Min Liu ◽  
Xing Ai ◽  
Jun Zhao ◽  
Yong Hui Zhou
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Relative Density ◽  
Sintering Temperature ◽  
Ceramic Composites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

Al2O3-TiC-ZrO2ceramic composites (ATZ) were fabricated by hot-pressed sintering. The phases and microstructure of the composites were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The relative density and mechanical properties (flexural strength, fracture toughness and Vicker’s hardness) of the composites were tested. The results show that the microstructure of the composites was the gray core-white rim. With the increase of sintering temperature, the relative density and mechanical properties of the composites increased first and then decreased. The composite sintered at 1705°C has the highest synthetical properties, and its relative density, flexural strength, fracture toughness and Vickers hardness are 98.3%,970MPa,6.0 MPa•m1/2and 20.5GPa, respectively.

Effect of BN Short Fiber Content on Mechanical Properties of ZrB2-SiC UHTCs

2012 ◽  
Vol 512-515 ◽  
pp. 706-709 ◽  
Author(s):  
Chang Ling Zhou ◽  
Yan Yan Wang ◽  
Zhi Qiang Cheng ◽  
Chong Hai Wang ◽  
Rui Xiang Liu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Scanning Electron Microscopy ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Ceramic Composites ◽  
Short Fiber ◽  
Hot Pressing Sintering ◽  
Scanning Electron

ZrB2-20%volSiC ceramic composites with different volume of BN short fiber were fabricated by the hot-pressing sintering under 2000°C. The content of BN short fiber changed from 0 to 15vol%. The density, flexural strength, fracture toughness and thermal expansions coefficient were studied. The microstructures of the samples were observed by scanning electron microscopy. The results show that the introducing of BN short fiber into the ZrB2-20%volSiC lead to a serious of change to the mechanical properties of the ceramic. When the content of the BN short fiber is 10vol%, the flexural strength and fracture toughness reach 422.1MPa and 6.15 MPa•m 1/2 respectively. And the mechanism of the increasing toughness was studied.

Mechanical Characterizations of Saxidomus purpuratus Shells

2010 ◽  
Vol 434-435 ◽  
pp. 601-604 ◽  
Author(s):  
W. Yang ◽  
Y. Jiang ◽  
G.P. Zhang ◽  
Y.S. Chao ◽  
Xiao Wu Li
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Bending Strength ◽  
Target Material ◽  
Organic Matrix ◽  
Fatigue Tests ◽  
Bending Fatigue ◽  
Three Point Bending ◽  
Saxidomus Purpuratus ◽  
Scanning Electron

A sort of biological shells (Saxidomus purpuratus), which belongs to Bivalve, was selected as the target material, and hardness and dynamic three point bending fatigue tests were conducted to examine its mechanical properties. Microhardness measurements showed that the inner layer is the hardest. The indentation on the specimen with a lower bending strength was damaged more seriously by the same load. Three point bending fatigue tests demonstrated that this kind of the shells with a special structure comprising mineral and organic matrix can experience the repeated loads instead of immediate breaking. The fatigue results on a single shell investigated here indicated that the fatigue strength is usually less than the static bending strength. Most of the fatigue lives of the specimens are less than 2105 cycles. In addition, fatigue fracture surfaces are observed by scanning electron microscopy.

STUDY OF MECHANICAL PROPERTIES AND FRACTURE MODE OF ALUMINA-SILICON CARBIDE NANOCOMPOSITES

2012 ◽  
Vol 05 ◽  
pp. 551-558 ◽  
Author(s):  
A. RAHIMNEZHAD YAZDI ◽  
H.R. BAHARVANDI ◽  
H. ABDIZADEH ◽  
N. EHSANI
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Silicon Carbide ◽  
Flexural Strength ◽  
Fracture Mode ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sic Particles ◽  
Scanning Electron

In this study Al 2 O 3- SiC nanocomposites have been fabricated by mixing of alumina and silicon carbide nano powders, followed by hot pressing at 1700°C. The mechanical properties and fracture mode of Al 2 O 3- SiC nanocomposites containing different volume fractions (5, 10 and 15%) of nano scale SiC particles were investigated and compared with those of alumina. Al 2 O 3- SiC powders were prepared by planetary milling in isopropanol. Fracture mode of specimens was investigated by means of scanning electron microscopy. Nanocomposites were tougher than alumina when they were hot pressed at the same temperature, and the values of nanocomposite's flexural strength and hardness were higher than those of alumina. Flexural strength, hardness and fracture toughness of the nanocomposites increase by increasing the volume percent of SiC up to 10% and then decrease slightly. The Scanning electron microscopy observations showed that fracture mode changes from intergranular for alumina to transgranular for nanocomposites. Finally X-ray diffraction analysis couldn't detect any chemical reactions between Al 2 O 3 and SiC particles.

Effect of Ti Element on the Mechanical Properties of Cu-Matrix Bonding Diamond Tool Bits

2016 ◽  
Vol 849 ◽  
pp. 865-868
Author(s):  
Chang Jiang Xiao
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Flexural Strength ◽  
Scanning Electron Microscope ◽  
Diamond Tool ◽  
Interface Bonding ◽  
Hot Pressing Sintering ◽  
Sintering Method ◽  
Ti Content ◽  
Scanning Electron

Using the hot-pressing sintering method, Cu-matrix bonding diamond tool bits including 0, 4 and 8 % Ti content (wt.%) were prepared. The effect of Ti content on the mechanical properties of Cu-matrix bonding diamond tool bits was studied. The experimental results showed that the influence of Ti content on the flexural strengths of Cu-matrix bonding bits and diamond tool bits are significant. Furthermore, the morphologies and compositions of fracture surfaces of diamond tool bits were characterized by scanning electron microscope and energy dispersive spectroscopy. The results illustrated that when the Ti content was 4%, the interface bonding between the diamond and the Cu-matrix bonding was the strongest, the flexural strength had the maximum values of the Cu-matrix bonding bits and the diamond tool bits, the values were 644 MPa and 515.8 MPa respectively.

Sintering of Ti3SiC2 Ceramics by Hot Press from Commercial Powders

2015 ◽  
Vol 655 ◽  
pp. 68-71
Author(s):  
Yuan Yuan Zhu ◽  
Jin Jia ◽  
Ai Guo Zhou ◽  
Li Bo Wang ◽  
Qing Feng Zan
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Sintering Temperature ◽  
Hot Press ◽  
X Ray Diffraction ◽  
X Ray ◽  
Three Point Bending ◽  
Ternary Compounds ◽  
Scanning Electron

Layered ternary compounds Ti3SiC2combines attractive properties of both ceramics and metals, and has been suggested for potential engineering applications. Near-fully dense Ti3SiC2bulks were sintered from commercial Ti3SiC2powders by hot press at 1350°C-1600°C for 60-120min under Ar atmosphere in this paper. The phase compositions and morphology of the as-prepared samples were evaluated by X-Ray diffraction (XRD) and scanning electron microscopy (SEM). And the mechanical properties were measured by Three-Point bending method. It was found that the Ti3SiC2had only a little of decomposition at sintering temperature above 1350°C. And effects of sintering temperature and holding time on the morphology of the bulk Ti3SiC2are not obvious. Relative density of 98% and flexural strength of 480MPa were obtained for the Ti3SiC2samples sintered at 30MPa and 1400°C for 90min.

TiCN-Based Cermets Strengthened with SiC Nano-Whiskers by Spark Plasma Sintering

2012 ◽  
Vol 512-515 ◽  
pp. 932-935
Author(s):  
Ying Peng ◽  
Zhi Jian Peng ◽  
Xiao Yong Ren ◽  
Hui Yong Rong ◽  
Cheng Biao Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Flexural Strength ◽  
Spark Plasma Sintering ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Addition Amount ◽  
Scanning Electron

TiCN-based cermets with different amounts of SiC nano-whiskers were prepared by spark plasma sintering. The microstructure and mechanical properties of the as-prepared cermets were investigated. X-ray diffraction revealed that there were no SiC peaks detected, turning out some peaks of new carbide and silicate hard phases. Scanning electron microscopy indicated that there were more and more pores in the cermets with increasing amount of SiC whisker added, and the fracture mechanism of the cermets was mainly inter-granular fracture. With increasing addition amount of nano-SiC whisker, the hardness and flexural strength of the cermets increased first and decreased then, presenting the highest hardness (2170 HV) and flexural strength (750 MPa), respectively, when the addition content of nano-whiskers is 2.5 wt%.

Electrical and Mechanical Properties of ZrB2-Based Composite Ceramic

2012 ◽  
Vol 512-515 ◽  
pp. 744-747 ◽  
Author(s):  
Yan Yan Wang ◽  
Kai Liu ◽  
Chang Ling Zhou ◽  
Chong Hai Wang ◽  
Rui Xiang Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Flexural Strength ◽  
Conduction Mechanism ◽  
Composite Ceramic ◽  
Pressureless Sintering ◽  
Mass Ratio ◽  
Sic Composites ◽  
Scanning Electron

The ZrB2-SiC composite ceramic was prepared using Al2O3 and Y2O3 as additives through pressureless sintering under 1800°C. The electrical and mechanical properties were studied with the different mass ratio of ZrB2 and SiC. The microstructure and phase transformation of the ZrB2-SiC composites ceramic were characterized by scanning electron microscopy. Results show that the densities of the samples are decreased with the decrease of the mass ratio of ZrB2 and SiC while the resistivities are increased. When the mass ratio of ZrB2 and SiC is 4 the resistivity reaches 14μΩ•mm while the density is 4.85g/cm3. When the mass ratio of ZrB2 and SiC is13:7, the flexural strength reaches the max value and toughness reaches the minimum value. The flexural strength reaches 233Mpa and the toughness reaches 4.51 Mpa• m 1/2. The changes of the properties of the ceramic were analyzed through the microstructure and the conduction mechanism was studied.

Multiscale Characterization of Nanocomposites Fabricated by Copulverization of Epoxy Resin and Nanoclay

Materials ◽  
2005 ◽  
Author(s):  
Levent Aktas ◽  
Sudha Dharmavaram ◽  
M. Cengiz Altan
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Flexural Strength ◽  
Epoxy Resin ◽  
Fine Powder ◽  
Bending Test ◽  
Scanning Electron Micrographs ◽  
Nanoclay Content ◽  
Scanning Electron

Effect of nanoclay on the thermo-mechanical properties of BT250E-1 epoxy resin is investigated. Nanocomposite parts containing 0, 2 and 10wt. % of Cloisite® 30B nanoclay are fabricated by copulverization of nanoclay with epoxy resin at −25°C. Desired amounts of solid epoxy resin and nanoclay are placed into a grinder and copulverized for 20 seconds. The resulting fine powder is then cured using an APA2000 rheometer by using the time-temperature profile provided by the resin supplier. Five disk-shaped parts for each nanoclay content are fabricated. Two rectangular samples are cut out from each disk and used for characterization of mechanical properties and microstructure. Glass transition temperature is observed to deteriorate by 5% and 10% with the addition of 2 and 10wt. % nanoclay, respectively. Three-point bending test results indicate up to 28% improvement in flexural stiffness whereas flexural strength is observed to degrade by 57% over the range of nanoclay loading. Scanning electron microscopy indicates extensive nanoclay agglomeration. In order to characterize the nanoclay cluster morphology, several scanning electron micrographs are captured at 500x magnification. Nanoclay clusters and their size distribution are then identified by digital image processing. It is found that the average cluster size is 2-fold higher at nanocomposites containing 10wt.% nanoclay compared to 2wt.%. Transmission electron microscopy indicates several nanovoids trapped in the intra-cluster regions. The existence of these voids is also verified by density measurements of the cured samples of the epoxy with and without nanoclay. The reduction observed in the flexural strength is believed to be due to these nanovoids and nanoclay agglomeration.

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