Mechanical Properties of CaB6 Sintered Body

2005 ◽  
Vol 297-300 ◽  
pp. 2707-2712
Author(s):  
Guang Hui Min ◽  
Li Xia Yang ◽  
Hua Shun Yu ◽  
Jiande Han
Keyword(s):  
Fracture Toughness ◽  
Fracture Surface ◽  
Intergranular Fracture ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Fracture Morphology ◽  
Sintered Body ◽  
Full Density ◽  
Transgranular Fracture ◽  
Sintering Aid

In this paper, CaB6 sintered body was fabricated by hot-pressed sintering with/without nickel as a sintering aid. The microstructure and fracture morphology were observed by means of SEM. CaB6 polycrystalline hot-pressed at 2123K showed insufficient densification. Fracture surface revealed that the existence of pores and the poor grain boundaries made the occurrence of intergranular fracture. When 28wt% nickel was added, nearly full density was obtained, although the sintering temperature is 200K lower. Hardness, Bending strength and fracture toughness of polycrystalline CaB6 were measured. By adding the Ni in CaB6 matrix, the flexural strength and the fracture toughness were enhanced, and the ratio of transgranular to intergranular fracture type was increased notably. The fracture surface showed a transgranular fracture. The crack bridging, micro-cracking and crack deflecting were deemed as the contribution to the improved fracture toughness.

Microstructure and Properties of Al2O3-ZrO2 Ceramics Prepared by Microwave Sintering

2014 ◽  
Vol 633 ◽  
pp. 193-197 ◽  
Author(s):  
Yun Long Ai ◽  
Xiang Hua Xie ◽  
Wen He ◽  
Bing Liang Liang ◽  
Wei Hua Chen
Keyword(s):  
Mechanical Properties ◽  
Intergranular Fracture ◽  
Fracture Mode ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Microwave Sintering ◽  
Transgranular Fracture ◽  
Submicron Scale ◽  
Main Fracture ◽  
Sintering Processes

ZrO2 doped with 7.5% (volume percent) nanoalumina ceramics were prepared by microwave sintering processes. The effects of nanoalumina additions and various sintering temperature on densification, phase composition, microstructure and mechanical properties of Al2O3-ZrO2 ceramics were investigated. The results show that the m-ZrO2 phase transformed into t-ZrO2 during the process of microwave sintering. Relative densities between 95% and 99% were attained in the different conditions. In any cases the grain size was maintained at a submicron scale at a processing microwave sintering. The presence of Al2O3 grains had an effect of hindering grain growth of ZrO2 grains. When the microwave sintering temperature was 1500°C, 7.5Al2O3-ZrO2 composite ceramics presented excellent mechanical properties: HV=12.0 GPa, σf=715.7 Mpa, KIC=11.9 MPa·m1/2. Compared with that of pure ZrO2 ceramic, the bending strength and the fracture toughness were improved 45% and 23% at least, respectively. The fracture mode was associated with sintering temperature: when the sintering temperature was 1350°C~1450°C, the intergranular fracture and transgranular fracture coexisted; when the sintering temperature was 1500°C, intergranular fracture was the main fracture mode.

The Influence of Sintering Temperature on the Mechanical Properties and Microstructure of Carbon Nanotubes/Zirconia/Hydroxyapatite Biocomposites

2013 ◽  
Vol 423-426 ◽  
pp. 38-42
Author(s):  
Ai Min Li ◽  
Kang Ning Sun ◽  
Run Hua Fan
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Fracture Toughness ◽  
Fracture Surface ◽  
Bending Strength ◽  
Electronic Materials ◽  
Sintering Temperature ◽  
Testing Machine ◽  
Materials Testing ◽  
Hot Pressing Sintering

Carbon nanotubes/zirconia/hydroxyapatite biocomposites was prepared by hot-pressing sintering under Ar atmosphere. The influence of sintering temperature on the mechanical properties and microstructure of carbon nanotube/zirconia/hydroxyapatite biocomposites was studied. We tested the bending strength and fracture toughness by universal electronic materials testing machine. The component of the composites was tested by XRD. The fracture surface of the composites was observed by SEM. The results indicate that the bending strength and fracture toughness of the composites is lower when the sintering temperature is lower than 1200°C. The difference of bending strength and fracture toughness at 1200°C and 1300°C is little. The number of them has risen markedly than the low temperature which reached to189.2MPa and 1.8MPa·m-1/2 respectively. The composition of the composites is mainly of hydroxyapatite, zirconia, carbon nanotubes, and a small amount of calcium phosphate, which indicated that part of the hydroxyapatite has decomposed. SEM photographs show that the fracture surface of the composites sintered at 1200 °C and 1300 °C is ductile fracture status and has bigger density.

Effects of TiN Content on Mechanical Properties and Microstructure of ATN Materials

2013 ◽  
Vol 589-590 ◽  
pp. 590-593 ◽  
Author(s):  
Min Wang ◽  
Jun Zhao
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Fracture Toughness ◽  
Vickers Hardness ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Ceramic Materials ◽  
Hot Press ◽  
Hot Press Sintering ◽  
Tin Content

In order to investigate the effects of TiN content on Al2O3/TiN ceramic material (ATN), the ATN ceramic materials were prepared of TiN content in 30%, 40%, 50%, 60% in the condition of hot press sintering. The sintering temperature is 1700°C, the sintering press is 32MPa, and the holding time are 5min, 10min, 15min. The effects of TiN content on mechanical properties and microstructure of ATN ceramic materials were investigated by analyzing the bending strength, hardness, fracture toughness. The results show that ATN50 has the best mechanical property, its bending strength is 659.41MPa, vickers hardness is 13.79GPa, fracture toughness is 7.06MPa·m1/2. It is indicated that the TiN content has important effect on microstructure and mechanical properties of ATN ceramic materials.

Microstructure and Mechanical Properties of Spark-Plasma-Sintered SiC-TiC Composites

2005 ◽  
Vol 287 ◽  
pp. 335-339 ◽  
Author(s):  
Kyeong Sik Cho ◽  
Kwang Soon Lee
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Heating Rate ◽  
Spark Plasma Sintering ◽  
Sintering Temperature ◽  
Applied Pressure ◽  
Argon Atmosphere ◽  
Full Density ◽  
Plasma Sintering ◽  
Spark Plasma

Rapid densification of the SiC-10, 20, 30, 40wt% TiC powder with Al, B and C additives was carried out by spark plasma sintering (SPS). In the present SPS process, the heating rate and applied pressure were kept at 100°C/min and at 40 MPa, while the sintering temperature varied from 1600-1800°C in an argon atmosphere. The full density of SiC-TiC composites was achieved at a temperature above 1800°C by spark plasma sintering. The 3C phase of SiC in the composites was transformed to 6H and 4H by increasing the process temperature and the TiC content. By tailoring the microstructure of the spark-plasma-sintered SiC-TiC composites, their toughness could be maintained without a notable reduction in strength. The strength of 720 MPa and the fracture toughness of 6.3 MPa·m1/2 were obtained in the SiC-40wt% TiC composite prepared at 1800°C for 20 min.

Pressureless Sintering and Properties Investigation of Silicon Nitride

2011 ◽  
Vol 194-196 ◽  
pp. 1464-1469
Author(s):  
Bin Li ◽  
Yi Feng ◽  
Hui Qiang Liu ◽  
Yan Fang Zhu ◽  
Dong Bo Yu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Bending Strength ◽  
Fracture Morphology ◽  
Pressureless Sintering ◽  
Sintering Aids ◽  
Α Phase ◽  
Different Grain Size ◽  
Si3n4 Ceramics

Different grain size of starting powder was choosed and different sintering additives were used to fabricate Si3N4 ceramics by pressureless sintering. Samples’ relative density and mechanical properties including Vickers hardness, bending strength and fracture toughness were tested. Then XRD, SEM and EDS were carried out to identify phase and observe microstructure and fracture morphology. The result shows that high purity α phase Si3N4 powder of 5 μm is suitable for sintering and combination of 5 wt.% MgO +5 wt.% Y2O3 is most effective within six kinds of sintering aids.

Preparation of Porous ZrO2-Al2O3 Composite Ceramic with High Strength and Good Corrosion-Resistance

2011 ◽  
Vol 197-198 ◽  
pp. 1545-1548 ◽  
Author(s):  
Qi Bing Chang ◽  
Xing Qin Liu ◽  
Xia Wang ◽  
Yong Qing Wang ◽  
Jian Er Zhou
Keyword(s):  
Corrosion Resistance ◽  
Bending Strength ◽  
Sintering Temperature ◽  
High Strength ◽  
Composite Ceramic ◽  
Ceramic Membranes ◽  
Porous Ceramics ◽  
Sintering Aid ◽  
Filtration Membrane ◽  
Before And After

In order to develop porous ceramics with high strength and corrosion resistance as the support for the preparation of asymmetric ceramic membranes, porous ZrO2-Al2O3 composite is designed and fabricated by adding Zr(OH)4.as sintering aid. The content of Zr(OH)4, the sintering temperature and the bending strength before and after corrosion of the composite are discussed. The results shows that 10wt% ZrO2-10wt% Zr(OH)4 -80wt%Al2O3 composite bar fabricated by cold press with the porosity of 32% can be fabricated in 1550°C for 4 h. The bending strength of the composite is 111.2MPa. After corrosion, the quality lose and the bending strength lose is no more than 1%. The tubular composite is suit for the preparation of micro-filtration membrane.

Study of the mechanical properties and toughening mechanism of ZrO2 particles toughened Si3N4 ceramics

2020 ◽  
Vol 10 (6) ◽  
pp. 928-933
Author(s):  
Liang Tian ◽  
Qinglin Hou ◽  
Yingxia Wang ◽  
Yihui Hou
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Sintering Temperature ◽  
High Hardness ◽  
Fracture Morphology ◽  
Xrd Analysis ◽  
High Thermal Stability ◽  
Toughening Mechanism ◽  
Temperature Resistance ◽  
Si3n4 Ceramics

Si3N4 ceramic has excellent properties such as high temperature resistance, high hardness, and high thermal stability, but it has the disadvantages of high hardness and brittleness and difficulty in later processing. In this paper, ZrO2 was used as toughening phase, and ZrO2 toughened Si3N4 ceramics was prepared by injection molding. The effects of ZrO2 sintering temperature and content on the mechanical properties and fracture morphology were studied. Experiments show that when the ZrO2 content is 10 wt.% and the sintering temperature reaches 1650 °C, the bending strength and fracture toughness of Si3N4 ceramics reach the maximum at the same time, which are 767 MPa and 8.7 MPa·m1/2, respectively. The density is high. XRD analysis revealed that if the sintering temperature is too high, the ZrO2/Si3N4 system will generate a large number of ZrN impurity phases that cannot be phase-transformed, which ultimately affects the ceramic properties. According to fracture morphology, the toughening mechanism of ZrO2 is stress-induced phase transition.

Mechanical and Wear Properties of Al2O3-15wt%ZrO2 Composites

2007 ◽  
Vol 280-283 ◽  
pp. 1049-1052
Author(s):  
Ping Gen Rao ◽  
Jian Qing Wu ◽  
Jian Dong Ye ◽  
Ying Jun Wang ◽  
Mikio Iwasa
Keyword(s):  
Fracture Toughness ◽  
Wear Resistance ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Precipitation Method ◽  
Alumina Powder ◽  
Wear Properties ◽  
Temperature Range ◽  
Al2o3 Matrix

A commercial a-alumina powder was mixed with Zr(OH)4 gel synthesized by a precipitation method. The mixture was calcined at 600°C for 2h. The Al2O3−15 wt% ZrO2 composites were sintered for 2 h in the temperature range between 1400°C and 1650°C in air. At the sintering temperature of 1550°C the highest density, the best wear resistance, the maximum bending strength of 708 MPa and the highest fracture toughness of 5.8 MPa×m1/2 were achieved, respectively. Improvement of the mechanical and wear properties of the Al2O3 matrix should mainly be attributed to the addition of ZrO2.

Charactering and Sintering of BaZrO3 Doped with TiO2

2011 ◽  
Vol 492 ◽  
pp. 312-315
Author(s):  
Cheng Zhang ◽  
Na Zhang ◽  
Dan Yu Jiang ◽  
Ling Cong Fan
Keyword(s):  
Solid State ◽  
Single Phase ◽  
Sintering Temperature ◽  
Full Density ◽  
Solid State Chemistry ◽  
Sintered Ceramic ◽  
Sintering Aid ◽  
Ceramic Block ◽  
Pure Phase ◽  
Low Levels

The high sintering temperatures required for solid-state derived powders is a significant obstacle inhibiting more widespread use of single pure phase BaZrO3with high density. The aim of this research was to reduce the sintering temperature whilst maintaining pure single phase BaZrO3. By using of sintering aid, such as TiO2additive, the pure perovskite BaZrO3powder have been fabricated with the solid state chemistry at 1250°C. Low levels of TiO2(3%) produced the pure BaZrO3particles with the smallest size, and the corresponding sintered ceramic has the density of 95% theoretical using sintering temperature as low as 1550°C. The microstructure of the particular ceramic with full density confirmed that the particle grain in ceramic block have shaped with the less pore and connected thickly.

Fatigue Life Properties and Anomalous Macroscopic Fatigue Fracture Surfaces of Low Carbon Steel JIS-SM490B in High-Pressure Hydrogen Gas Environment

2016 ◽  
Author(s):  
Yuhei Ogawa ◽  
Hisao Matsunaga ◽  
Michio Yoshikawa ◽  
Junichiro Yamabe ◽  
Saburo Matsuoka
Keyword(s):  
Fracture Toughness ◽  
Fatigue Life ◽  
Fracture Surface ◽  
Crack Growth ◽  
Fracture Process ◽  
Fracture Morphology ◽  
Hydrogen Gas ◽  
Stage Iii ◽  
Fracture Surfaces ◽  
Stage Stage

Tension-compression fatigue tests using smooth specimens of low carbon steel JIS-SM490B were carried out in air and hydrogen gas environment under the pressure of 0.7 and 115 MPa at room temperature. In 0.7 MPa hydrogen gas, fatigue life curve was nearly equivalent to that in air. On the other hand, in 115 MPa hydrogen gas, fatigue life was significantly degraded in the relatively short fatigue life regime (e.g. Nf < 105). To clarify the effect of hydrogen environment on fracture process, fracture surfaces of these specimens were observed. In general, fatigue fracture process of steels with low or moderate strength is macroscopically divided into 3 stages. In the first stage (stage I), fatigue cracks initiate in some crystalline grains. In the second stage (stage II), the cracks propagate stably on a cycle-by-cycle basis. In the final stage (stage III), a tilted fracture surface, shear-lip, is formed by ductile tearing. In SM490B steel, this general fracture process was confirmed in air and 0.7 MPa hydrogen gas. In contrast, in 115 MPa hydrogen gas, there was no tilted portion in the stage III region, and the fracture surface was totally flat. Observation with scanning electron microscope revealed that dimples were formed by ductile tearing in the tilted fracture region in air and 0.7 MPa hydrogen gas. On the other hand, only a quasi-cleavage fracture surface existed in the final fracture region in 115 MPa hydrogen gas. To understand the cause of this peculiar fracture morphology, we conducted elasto-plastic fracture toughness tests in each environment, and investigated the fracture morphology. As a result of fracture toughness tests, crack growth rate in air and 0.7 MPa hydrogen gas was approximately equal to each other, and both the fracture surfaces were covered by dimples. This fracture morphology was in accordance with that of stage III morphology in fatigue specimen tested in air and 0.7 MPa hydrogen gas. However, in 115 MPa hydrogen gas, the crack growth was significantly accelerated, and the whole fracture surface was covered by quasi-cleavage. In this paper, firstly, the similarity of fracture surface between two test methods, i.e. fatigue test and fracture toughness test, is investigated. And then, the formation mechanism of the flat fracture surface is discussed by paying attention to the crack-growth acceleration in high-pressure hydrogen gas.

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