scholarly journals The effect of various Co contents on the microstructure and properties of Ti(C,N)-TiB2-Co cermets prepared in situ via reactive hot pressing

2020 ◽  
Vol 12 (5) ◽  
pp. 168781402092571
Author(s):  
Xianrui Zhao ◽  
Ze Yu ◽  
Dunwen Zuo ◽  
Qintao Li ◽  
Mengxian Zhang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Relative Density ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Hardness Test ◽  
Reactive Hot Pressing ◽  
Compacting Pressure ◽  
Vickers Hardness Test ◽  
Scanning Electron

Ti(C,N)-TiB2-Co cermets were in situ synthesized, via reactive hot pressing from the Co-Ti-C-BN system, with a Co content ranging from 6 to 22 wt%. The microstructure, relative density, hardness, and fracture toughness of the sintered compacts was investigated by light microscopy, scanning electron microscopy, ceramic densitometry, and Vickers hardness test. The investigations indicate that during hot pressing (compacting pressure = 30 MPa), when the Co content is 14–22 wt%, the metal binder is extruded. Co and Ti are included in the extrudate, breaking the original ratio and deteriorating the properties of the sintered products. As the Co content increases from 6 wt% to 12 wt%, the porosity increases, and the relative density increases from 97.2% to 99.5%. The fracture toughness increases from 6.1 to 6.8 MPa m1/2. The Vickers hardness first increases from 1897 HV10 to the maximum 1960 HV10 and then decreases slightly to 1945 HV10.

Effect of TiC Content on the Microstructure and Mechanical Properties of Ti3AlC2/Al2O3 In Situ Composites Synthesized by Hot Pressing

2012 ◽  
Vol 724 ◽  
pp. 278-281 ◽  
Author(s):  
Lan Ye ◽  
Jian Feng Zhu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Composition ◽  
Flexural Strength ◽  
High Temperatures ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Microstructure And Mechanical Properties ◽  
Reactive Hot Pressing

The Ti3AlC2/Al2O3 in situ composites were successfully synthesized from the system of Ti-TiC-Al-TiO2 by reactive hot pressing at 1350 °C. The effect of TiC content on the phase composition, microstructure and mechanical properties were investigated in detail. The results indicate that the fabricated products possess the highest purity as the TiC contents reduce to 90 % of its theoretical content. This deviation is mainly attributed to the decomposition of Ti3AlC2 and vaporization of Al at high temperatures. The effect of TiC content on the fracture toughness, flexural strength, Vickers hardness of Ti3AlC2/Al2O3 composites was also discussed in detail.

Microstructure and Mechanical Properties of TiC/Ti3AlC2 In Situ Composites Prepared by Hot Pressing Method

2015 ◽  
Vol 816 ◽  
pp. 200-204 ◽  
Author(s):  
Miao Miao Ruan ◽  
Xiao Ming Feng ◽  
Tao Tao Ai ◽  
Ning Yu ◽  
Kui Hua
Keyword(s):  
Fracture Toughness ◽  
Flexural Strength ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Sintering Temperature ◽  
Powder Mixtures ◽  
Pressing Method ◽  
Hot Pressing Sintering ◽  
Sintering Method

TiC/Ti3AlC2 composites were successfully prepared by hot-pressing sintering method from the elemental powder mixtures of Ti, Al and TiC. A possible reaction mechanism was investigated by XRD. The density, Vickers hardness, flexural strength, and fracture toughness of the TiC/Ti3AlC2 composites were also measured. At 660 °C, Al melted and reacted with Ti to form TiAl3. At 900 °C, TiAl3 reacted with TiC and Ti to form Ti2AlC. At 1100 °C, Ti2AlC reacted with TiC to form Ti3AlC2. Increasing the sintering temperature, the content of Ti3AlC2 increased. The TiC/Ti3AlC2 composites had excellent performance after sintered at 1100 °C, the density, Vickers hardness, flexural strength and fracture toughness of the composite were 4.35 g/cm3, 4.72 GPa, 566 MPa and 6.18 MPa·m1/2, respectively.

scholarly journals Микротвердость и трещиностойкость оксида галлия

2019 ◽  
Vol 45 (21) ◽  
pp. 51
Author(s):  
В.И. Николаев ◽  
А.В. Чикиряка ◽  
Л.И. Гузилова ◽  
А.И. Печников
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Temperature ◽  
Vickers Hardness ◽  
Gallium Oxide ◽  
Hardness Test ◽  
Test Method ◽  
Vickers Hardness Test

The microhardness and the fracture toughness of two main polytypes of gallium oxide (a metastable α-Ga2O3 and thermodynamically stable high-temperature β-Ga2O3 phase) have been investigated. The measurements were carried out by the Vickers hardness test method. This is the first attempt to compare the mechanical properties of various polytypes of gallium oxide.

Microstructure and Mechanical Properties of ZrB2-Based UHTC via Reactive Hot Pressing

2008 ◽  
Vol 368-372 ◽  
pp. 1737-1739
Author(s):  
Qiang Qu ◽  
Wen Bo Han ◽  
Song He Meng ◽  
Xing Hong Zhang ◽  
Jie Cai Han
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Fracture Toughness ◽  
High Temperature ◽  
Hot Pressing ◽  
Sintering Temperature ◽  
Volume Ratio ◽  
Ultra High Temperature Ceramics ◽  
Reactive Hot Pressing

ZrB2-based ultra-high temperature ceramics (UHTCs) were prepared from a mixture powder of Zr/B4C/Si with different ratio via reactive hot pressing. The experimental results showed that the sintering temperature above 1800°C was necessary for enhancing the activity of the powders and thus improving the densification of the product. The sinterability and densification properties of ZrB2-based UHTCs meliorated with the amount of Si increasing. However, many large ZrB2 agglomerates formed when the amount of synthesized SiC in the product reached 25vol%, which led to decrease the mechanical property. The composite had highest mechanical properties when the volume ratio of ZrB2: SiC: ZrC was 73.86:20:6.14, and its flexual strength and the fracture toughness were 645.8MPa and 5.66MPa·m1/2 respectively. The microstructure investigation showed the in-situ formed SiC and ZrC were located in the triple point of ZrB2 grains with a size less than 3μm.

The Influence of Holmium on the Microstructure and Hardness of Mg-Nd-Gd-Zn-Zr Alloys

2017 ◽  
Vol 740 ◽  
pp. 48-53 ◽  
Author(s):  
Rosli Ahmad ◽  
N.R. Shahizan ◽  
M.B.A. Asmael ◽  
Ashraf M.M. Elaswad
Keyword(s):  
Grain Size ◽  
Rare Earth ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Vickers Hardness ◽  
Volume Fraction ◽  
Hardness Test ◽  
Vickers Hardness Test ◽  
Scanning Electron ◽  
Zr Alloys

The influence of holmium on the microstructure and hardness of Mg-Nd-Gd-Zn-Zr alloys were investigated. Conventional casting methods are used to produce the alloys. All the results were characterized by optical microscopy, scanning electron microscope (SEM) and the Vickers hardness test to highlight the influence of holmium addition. The addition of 2.0 wt.% holmium leads to the combination of rare earth elements which formed Mg-Zn-Nd-Ho phase. The results have shown the addition of Ho improved the microstructure and hardness of Mg-Nd-Gd-Zn-Zr alloys. By adding grain size of 2.0 wt.% holmium had reduced by 18.43%, while the volume fraction increased by 7.34%. The Vickers hardness value improved 6.18% due to the grain refine and volume fraction precipitates. The 2.0 wt.% holmium addition showed a positive result in microstructure and hardness value.

scholarly journals Fabrication and mechanical properties of self-toughening ZrB2–SiC composites from in-situ reaction

2019 ◽  
Vol 8 (4) ◽  
pp. 527-536 ◽  
Author(s):  
Zhaofu Zhang ◽  
Jianjun Sha ◽  
Yufei Zu ◽  
Jixiang Dai ◽  
Yingjun Liu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Hot Pressing ◽  
High Fracture Toughness ◽  
High Fracture ◽  
Microstructure Observation ◽  
Pull Out ◽  
Sic Composites ◽  
Reactive Hot Pressing

AbstractSelf-toughening ZrB2–SiC based composites are fabricated by in-situ reactive hot pressing. The effect of sintering additive content on the microstructure and mechanical properties of the composites is investigated. Microstructure observation found that the in-situ reactive hot pressing could promote the anisotropic growth of ZrB2 grains and the formation of interlocking microstructure. Such microstructure could improve the mechanical properties, especially, for the fracture toughness. The improved mechanical properties could be attributed to the self-toughening structure related to the ZrB2 platelets and the formed interlocking microstructure, which could trigger various toughening mechanisms such as grain pull-out, crack bridging, crack deflection, and crack branching, providing the main contribution to the high fracture toughness.

Multiple Teeth Fractures in Dentinogenesis Imperfecta: A Case Report

2014 ◽  
Vol 38 (4) ◽  
pp. 362-365 ◽  
Author(s):  
B Min ◽  
J S Song ◽  
J H Lee ◽  
B J Choi ◽  
K M Kim ◽  
...  
Keyword(s):  
Vickers Hardness ◽  
Fracture Resistance ◽  
Surface Hardness ◽  
Hardness Test ◽  
Dentinogenesis Imperfecta ◽  
Enamel Microstructure ◽  
Multiple Fractures ◽  
Hereditary Defect ◽  
Vickers Hardness Test ◽  
Scanning Electron

Dentinogenesis imperfecta (DGI) is a hereditary defect consisting of opalescent teeth composed of irregularly formed and hypomineralized dentin. This paper presents the multiple fractures of DGI-affected teeth and suggests the reason of low fracture resistance by observing the dentin microstructures directly using scanning electron microscope (SEM) and by measuring its surface hardness using the Vickers hardness test. .SEM revealed that while the enamel microstructure was similar in the DGI-affected and normal teeth, the microstructure of the DGI-affected dentin was poorly woven and more loosely packed than that of the normal dentin. The Vickers hardness of the DGI-affected dentin was 4.89 times softer than the normal dentin. The low fracture resistance of DGI-affected teeth can be attributed to the poorly woven microstructure of their dentin, which leads to a reduction in hardness.

PECULIARITIES OF THE SYNTHESIS OF HIGH-TEMPERATURE CERAMICS TASI2–SIC, REINFORCED IN SITU BY DISCRETE SILICON CARBIDE NANOFIBERS

2018 ◽  
pp. 72-76
Author(s):  
S. Vorotilo ◽  
E. D. Polozova ◽  
E. A. Levashov
Keyword(s):  
Fracture Toughness ◽  
Silicon Carbide ◽  
High Temperature ◽  
Relative Density ◽  
Hot Pressing ◽  
Temperature Synthesis ◽  
Similar Composition ◽  
High Temperature Synthesis ◽  
Sic Ceramic

The possibility of the increase of the properties of ceramics in the TaSi2–SiC system via the reinforcement by the SiC nanofibers formed in situ in the combustion wave has been studied. For the formation of nanofibers as well as for increase of the exothermicity of the reaction mixtures, energetic additive PTFE (C2F4) was used. Using the method of self-propagating high-temperature synthesis of the mechanically activated mixtures, 70%TaSi2+30%SiC ceramic was produced, with SiC present as the round-shaped grains and as nanofibers. Ceramic specimens sintered by hot pressing were characterized by relative density up to 98 %, hardness 19,0–19,2 GPa and fracture toughness 7,5–7,8 MPa·m1/2, which is noticeably above the fracture toughness of the ceramic with similar composition produced without the PTFE additions.

scholarly journals Microstructure and mechanical properties of Ti3(Al,Ga)C2/Al2O3 composites prepared by in situ reactive hot pressing

2020 ◽  
Vol 9 (6) ◽  
pp. 782-790
Author(s):  
Yuan Fang ◽  
Xiaohua Liu ◽  
Yuxia Feng ◽  
Jianfeng Zhu ◽  
Wei Jiang
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Raw Materials ◽  
Second Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reactive Hot Pressing

AbstractIn this study, Ti3(Al,Ga)C2/Al2O3 composites were successfully synthesized by in situ hot pressing at 1350 °C for 2 h using Ti, Al, TiC, and Ga2O3 as raw materials. X-ray diffraction and scanning electron microscopy were used for characterizing the phase identities and microstructures of the sintered composites. The dependence of the Vickers hardness and flexural strength on the Al2O3 content was found to be in single-peak type. Ti3(Al0.6,Ga0.4)C2/10.3vol%Al2O3 composite exhibited significantly improved mechanical properties. Vickers hardness and flexural strength of the composite reached 6.58 GPa and 527.11 MPa, which were 40% and 74% higher than those of Ti3AlC2, respectively. Formation of solid solution and incorporation of second phase of Al2O3 resulted in the opposite influence on the fracture toughness. Finally, the hardening and strengthening mechanisms were discussed in detail.

Mechanical Properties and Oxidation Resistance of Hot Pressed B4C Ceramics Material

2011 ◽  
Vol 233-235 ◽  
pp. 2272-2275
Author(s):  
Xin Yan Yue ◽  
Bi Shuang Chen ◽  
Jing Zhao ◽  
Hong Qiang Ru ◽  
Wei Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Relative Density ◽  
Oxidation Resistance ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Experimental Results ◽  
Pressing Method

B4C ceramics were obtained using hot-pressing method. The effect of different sintering temperatures on the microstructures and mechanical properties of B4C ceramics were investigated. Oxidation resistances were studied over the range 600-850°C. The experimental results showed that the relative density, bending strength and fracture toughness all increased first and then decreased with increasing the sintering temperature. The Vickers-hardness increased as the sintering temperature increasing. When the sintering temperature was 1950°C, the B4C ceramics showed the optimized properties. The values of its relative density, Vickers-hardness, bending strength and fracture toughness were 99.1%, 34.0 GPa, 524.6 MPa and 6.56 MPa·m1/2, respectively.

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