Influence of Al2O3 Addition on the Microstructure and Mechanical Properties of Pressureless Sintered Ce-TZP

2005 ◽  
Vol 492-493 ◽  
pp. 783-0 ◽  
Author(s):  
Shui Gen Huang ◽  
Lin Li ◽  
Jef Vleugels ◽  
Pei Ling Wang ◽  
Omer Van der Biest
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Grain Growth ◽  
Vickers Hardness ◽  
Good Combination ◽  
Al2o3 Content ◽  
Pressureless Sintering ◽  
Sintering Time ◽  
Microstructure And Mechanical Properties

Mixtures of 12 mol% CeO2-stabilised ZrO2 with 5 to 20 wt % Al2O3 were prepared and densified through pressureless sintering in air at 1450° C for 1 to 4 h. The influence of the Al2O3 content and sintering time on the phase constitution, microstructure and mechanical properties of the as-sintered composites were investigated. Fully dense Ce-TZP/Al2O3 ceramics with a good combination of hardness and fracture toughness can be obtained by pressureless sintering in air for only 1 h. The addition of Al2O3 to Ce-TZP improves the mechanical properties and suppresses ZrO2 grain growth. The average ZrO2 grain size increases with increasing sintering time and decreasing Al2O3 content. This leads to an increase in toughness. An excellent fracture toughness of 14.3 MPam1/2 in combination with a Vickers hardness of 9.14 GPa was obtained for 12 mol % CeO2-TZP with 5 wt % Al2O3, sintered for 4 h.

Effect of (Ni,Mo) and (W,Ti)C on the Microstructure and Mechanical Properties of TiB2 Ceramic Tool Materials

2012 ◽  
Vol 723 ◽  
pp. 233-237 ◽  
Author(s):  
Tong Chun Yang ◽  
Chuan Zhen Huang ◽  
Han Lian Liu ◽  
Bin Zou ◽  
Hong Tao Zhu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Flexural Strength ◽  
Grain Growth ◽  
Vickers Hardness ◽  
Ceramic Tool ◽  
Tool Materials ◽  
Sintering Additive ◽  
Microstructure And Mechanical Properties

TiB2-(W,Ti)C composites with (Ni,Mo) as sintering additive have been fabricated by hot-pressing technique, and the microstructure and mechanical properties of the composites have been investigated. (Ni,Mo) promotes grain growth of the composites. In the case of 7vol.% (Ni,Mo), the grain size decreases consistently with an increase in the content of (W,Ti)C. When the proper content of (W,Ti)C is added to TiB2 composites, the growth of matrix grains is inhibited and the mechanical properties of the composites are improved. The best mechanical properties of the composites are 1084.13MPa for three-point flexural strength, 7.80MPa•m 1/2 for fracture toughness and 17.92GPa for Vickers hardness.

scholarly journals Microstructure and Properties of Ultrafine Cemented Carbides Prepared by Microwave Sintering of Nanocomposites

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 507
Author(s):  
Yanju Qian ◽  
Zhiwei Zhao
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Vickers Hardness ◽  
Sintering Temperature ◽  
Microwave Sintering ◽  
Raw Material ◽  
Cemented Carbides ◽  
Microstructure And Mechanical Properties ◽  
Average Grain Size

Ultrafine cemented carbides were prepared by microwave sintering, using WC-V8C7-Cr3C2-Co nanocomposites as a raw material. The effects of sintering temperature and holding time on the microstructure and mechanical properties of cemented carbides were studied. The results show that the ultrafine cemented carbides prepared at 1300 °C for 60 min have good mechanical properties and a good microstructure. The relative density, Vickers hardness, and fracture toughness of the specimen reach the maximum values of 99.79%, 1842 kg/mm2 and 12.6 MPa·m1/2, respectively. Tungsten carbide (WC) grains are fine and uniformly distributed, with an average grain size of 300–500 nm. The combination of nanocomposites, secondary pressing, and microwave sintering can significantly reduce the sintering temperature and inhibit the growth of WC grains, thus producing superfine cemented carbides with good microstructure and mechanical properties.

scholarly journals Densification and Mechanical Properties of Alumina Ceramics via Two-Step Sintering With Different Holding Times

2021 ◽  
Vol 6 (4) ◽  
pp. 299-304
Author(s):  
Anis Syufina Mohammad Saufi ◽  
Ramesh Singh ◽  
K. Y. Sara Lee ◽  
Tao Wu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Relative Density ◽  
Grain Growth ◽  
Vickers Hardness ◽  
Holding Time ◽  
Alumina Ceramics ◽  
Conventional Sintering ◽  
Viable Approach

The densification and mechanical properties of alumina ceramics were investigated via two-step sintering (TSS) with different holding time. The alumina ceramics were sintered at 1450 °C for 1 min during the first stage, followed by sintering at 1350 °C with different holding times (2-24h). Conventional sintering (CS) was also performed on the alumina ceramics at 1450 °C for 2 h for comparison purpose. It was found that dense alumina with a relative density above 98% could be attained when TSS with a holding time of more than 12 h. The samples exhibited Vickers hardness between 5-8 GPa and fracture toughness of about 6 MPa.m1/2. In contrast, conventional sintered alumina yielded low relative density (85%), large grain size (2 μm), low Vickers hardness (4.23 GPa) and fracture toughness (4.73 MPa.m1/2). This study revealed that TSS is a viable approach in aiding densification, suppressing grain growth, and improving the mechanical properties of alumina ceramics.

scholarly journals Synthesis of "in situ" reinforced silicon nitride composites

2004 ◽  
Vol 69 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Aleksandra Vuckovic ◽  
Snezana Boskovic ◽  
Ljiljana Zivkovic
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Nitride ◽  
Pressureless Sintering ◽  
Sintering Additives ◽  
Sintering Time

The objective of this work was to investigate the effect of two different sintering additives (CeO2 and Y2O3 + Al2O3), sintering time and amount of ?-Si3N4 seeds on the densification, mechanical properties and microstructure of self-reinforced Si3N4 based composites obtained by pressureless sintering. Preparation of ?-Si3N4 seeds, also obtained by a pressureless sintering procedure, is described. Samples without seeds were prepared for comparison. The results imply that self-reinforced silicon nitride based composites with densities close to the theoretical values and with fracture toughness of 9.3MPa m1/2 can be obtained using a presureless sintering procedure.

scholarly journals Study on Microstructure and Mechanical Properties of WC-10Ni3Al Cemented Carbide Prepared by Different Ball-Milling Suspension

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2224 ◽  
Author(s):  
Minai Zhang ◽  
Zhun Cheng ◽  
Jingmao Li ◽  
Shengguan Qu ◽  
Xiaoqiang Li
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Ball Milling ◽  
Grain Growth ◽  
Organic Solvents ◽  
Crack Deflection ◽  
Cemented Carbides ◽  
Powder Metallurgy Method ◽  
Microstructure And Mechanical Properties ◽  
Α Al2o3

In this paper, WC-10Ni3Al cemented carbides were prepared by the powder metallurgy method, and the effects of ball-milling powders with two different organic solvents on the microstructure and mechanical properties of cemented carbides were studied. We show that the oxygen in the organic solvent can be absorbed into the mixed powders by ball-milling when ethanol (CH3CH2OH) is used as a ball-milling suspension. This oxygen leads to the formation of α-Al2O3 during sintering, which improves the fracture toughness, due to crack deflection and bridging, while the formation of η-phase (Ni3W3C) inhibits the grain growth and increases the hardness. Alternatively, samples milled using cyclohexane (C6H12) showed grain growth during processing, which led to a decrease in hardness. Therefore, the increase of oxygen content from using organic solvents during milling improves the properties of WC-Ni3Al composites. The growth of WC grains can be inhibited and the hardness can be improved without loss of toughness by self-generating α-Al2O3 and η-phase (Ni3W3C).

Microstructure and Mechanical Properties of SiC Whisker-Reinforced ZrB2 Ultra-High Temperature Ceramic

2008 ◽  
Vol 368-372 ◽  
pp. 1730-1732 ◽  
Author(s):  
Ping Hu ◽  
Xing Hong Zhang ◽  
Jie Cai Han ◽  
Song He Meng ◽  
Bao Lin Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Temperature ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Room Temperature ◽  
Pressing Temperature ◽  
Sintering Time ◽  
Microstructure And Mechanical Properties ◽  
Ultra High Temperature

SiC whisker-reinforced ZrB2 matrix ultra-high temperature ceramic were prepared at 2000°C for 1 h under 30MPa by hot pressing and the effects of whisker on flexural strength and fracture toughness of the composites was examined. The flexural strength and fracture toughness are 510±25MPa and 4.05±0.20MPa⋅m1/2 at room temperature, respectively. Comparing with the SiC particles-reinforced ZrB2 ceramic, no significant increase in both strength and toughness was observed. The microstructure of the composite showed that the SiC whisker was destroyed because the SiC whisker degraded due to rapid atom diffusivity at high temperature. The results suggested that some related parameters such as the lower hot-pressing temperature, a short sintering time should be controlled in order to obtain SiC whiskerreinforced ZrB2 composite with high properties.

scholarly journals Influence of Vacuum Heat Treatments on Microstructure and Mechanical Properties of M35 High Speed Steel

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 643
Author(s):  
Chiara Soffritti ◽  
Annalisa Fortini ◽  
Ramona Sola ◽  
Elettra Fabbri ◽  
Mattia Merlin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Vickers Hardness ◽  
High Speed ◽  
High Speed Steel ◽  
Plane Strain Fracture Toughness ◽  
Secondary Carbides ◽  
Heat Treated ◽  
Strain Fracture

Towards the end of the last century, vacuum heat treatment of high speed steels was increasingly used in the fabrication of precision cutting tools. This study investigates the influence of vacuum heat treatments at different pressures of quenching gas on the microstructure and mechanical properties of taps made of M35 high speed steel. Taps were characterized by optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, X-ray diffraction, apparent grain size and Vickers hardness measurements, and scratch tests. Failure analysis after tapping tests was also performed to determine the main fracture mechanisms. For all taps, the results showed that microstructures and the values of characteristics of secondary carbides, retained austenite, apparent grain size and Vickers hardness were comparable to previously reported ones for vacuum heat treated high speed steels. For taps vacuum heat treated at six bar, the highest plane strain fracture toughness was due to a higher content of finer small secondary carbides. In contrast, the lowest plane strain fracture toughness of taps vacuum heat treated at eight bar may be due to an excessive amount of finer small secondary carbides, which may provide a preferential path for crack propagation. Finally, the predominant fracture mechanism of taps was quasi-cleavage.

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.

Microstructure and Mechanical Properties of Hot Pressed ZrC-SiC-ZrB2 Composites

2010 ◽  
Vol 434-435 ◽  
pp. 173-177 ◽  
Author(s):  
Bao Xia Ma ◽  
Wen Bo Han ◽  
Xing Hong Zhang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Ceramic Composites ◽  
Strong Function ◽  
Slight Tendency ◽  
Microstructure And Mechanical Properties

Ternary ZrC-SiC-ZrB2 ceramic composites were prepared by hot pressing at 1900 °C for 60 min under a pressure of 30 MPa in argon. The influence of ZrB2 content on the microstructure and mechanical properties of ZrC-SiC-ZrB2 composites was investigated. Examination of SEM showed that the microstructure of the composites consisted of the equiaxed ZrB2, ZrC and SiC grains, and there was a slight tendency of reduction for grain size in ZrC with increasing ZrB2 content. The hardness increased considerably from 23.3 GPa for the ZS material to 26.4 GPa for the ZS20B material. Flexural strength was a strong function of ZrB2 content, increasing from 407 MPa without ZrB2 addition to 627 MPa when the ZrB2 content was 20vol.%. However, the addition of ZrB2 has little influence on the fracture toughness, ranging between 5.5 and 5.7 MPam1/2.

Effect of MgO-Y2O3 Additions on Microstructure and Mechanical Properties of Al2O3-TiCN Composites

2014 ◽  
Vol 1058 ◽  
pp. 176-179
Author(s):  
Zhi Lin Zhang ◽  
Wei Ming Guo ◽  
Shang Hua Wu ◽  
Yang You
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Growth ◽  
Abnormal Grain Growth ◽  
Microstructure And Mechanical Properties

The effect of MgO-Y2O3 additives on densification, microstructure and mechanical properties of hot-pressed Al2O3-TiCN composites was studied. The MgO-Y2O3 additions had little influence on densification of Al2O3-TiCN composites. The Al2O3-TiCN composites without additives had coarsening microstructure, whereas that containing 0.25wt%MgO-0.5wt%Y2O3 had a noticeable finer microstructure and good mechanical properties. The increase of fracture toughness were attributed to the addition of MgO and Y2O3 together with the TiCN particles to inhibit the abnormal grain growth of Al2O3.

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