Densification and Mechanical Properties of B4C Based Composites Sintered by Reaction Hot-Pressing

2010 ◽  
Vol 434-435 ◽  
pp. 24-27 ◽  
Author(s):  
Guo Feng Wang ◽  
Ji Hong Zhang ◽  
Chunping Zhang ◽  
Kai Feng Zhang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Residual Stress ◽  
Thermal Properties ◽  
Sintering Temperature ◽  
Crack Deflection ◽  
Sintering Behavior ◽  
Reaction Sintering ◽  
Boron Carbide B4c

Boron carbide (B4C) possesses unique physical and thermal properties. In this paper, B4C based composites toughened by TiB2 were fabricated by in-situ reaction sintering with the original microcrystalline powders B4C, TiO2 and glucose. The influences of sintering temperature and content of TiO2 on the sintering behavior and mechanical properties were investigated. (TiB2, Al2O3)/B4C and (TiB2,SiC)/B4C composites with almost fully dense were fabricated by using additives　of Al2O3 and Si powders and sintering at 1950°C and 1900°C, the fracture toughness of composites reach to 7.09 and 6.35 MPa•m1/2 respectively. The analysis of microstructure shows that the main toughen mechanism is the crack deflection due to the existence of residual stress.

Effect of Iron Additive on the Sintering Behavior of Hot-Pressed ZrC-W Composites

2008 ◽  
Vol 368-372 ◽  
pp. 1764-1766 ◽  
Author(s):  
Yu Jin Wang ◽  
Lei Chen ◽  
Tai Quan Zhang ◽  
Yu Zhou
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Relative Density ◽  
Sintering Temperature ◽  
Sintering Behavior ◽  
Hot Press ◽  
Sintering Additive ◽  
Microstructure And Mechanical Properties ◽  
Hot Press Sintering

The ZrC-W composites with iron as sintering additive were fabricated by hot-press sintering. The densification, microstructure and mechanical properties of the composites were investigated. The incorporation of Fe beneficially promotes the densification of ZrC-W composites. The relative density of the composite sintered at 1900°C can attain 95.3%. W2C phase is also found in the ZrC-W composite sintered at 1700°C. The content of W2C decreases with the increase of sintering temperature. However, W2C phase is not identified in the composite sintered at 1900°C. The flexural strength and fracture toughness of the composites are strongly dependent on sintering temperature. The flexural strength and fracture toughness of ZrC-W composite sintered at optimized temperature of 1800°C are 438 MPa and 3.99 MPa·m1/2, respectively.

Effect of Sintering Temperature on Microstructure and Mechanical Properties of Al2O3/TiAl In-Situ Composites

2011 ◽  
Vol 695 ◽  
pp. 227-230
Author(s):  
Liu Yi Xiang ◽  
Fen Wang ◽  
Jian Feng Zhu ◽  
Xiao Feng Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Hot Press ◽  
Rockwell Hardness ◽  
Dispersion Method ◽  
Powder Mixtures

Al2O3/TiAl composites were successfully fabricated by hot-press-assisted exothermic dispersion method with powder mixtures of Ti, Al, TiO2and Cr2O3as raw materials. The effect of sintering temperature on the microstructures and mechanical properties of Al2O3/TiAl composites has been investigated. The results show that the Rockwell hardness and density of the composites increased with increasing sintering temperature. But the flexural strength and fracture toughness peaked at 825 MPa and 7.29 MPa·m1/2, respectively, when the sintering temperature reached to1300 °C.

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.

Effect of In Situ Formed Spinel Phase on the Mechanical Properties of Zirconia Ceramics

2007 ◽  
Vol 345-346 ◽  
pp. 1573-1576
Author(s):  
Z. X. Yang ◽  
Jeong Bae Yoon ◽  
Kyu Hong Hwang ◽  
J.K. Lee ◽  
B.S. Jun
Keyword(s):  
Mechanical Properties ◽  
Spinel Phase ◽  
Sintering Behavior ◽  
Reaction Sintering ◽  
Stabilized Zirconia ◽  
Homogeneous Microstructure ◽  
Fine Grain ◽  
Firing Shrinkage ◽  
Spinel Mgal2o4

The reaction-sintered zirconia-alumina and zirconia-spinel ceramics having low firing shrinkage were prepared from ZrO2(Ca-PSZ)/Al and ZrO2(Baddellyite)/MgAl powder mixtures via the attrition milling and the effect of the characteristics of used raw powders was investigated. Flaky Al powders mixed with coarse Ca-PSZ powders was not effectively comminuted due to lower hardness of zirconia powders. So by using the alumina ball media or coarse Al2O3 powders rather than Al, the milling efficiency could be much more increased. When fused Ca-PSZ powder was reaction-sintered with Al at 1550 for 3 hours, the reaction-sintering and densification were somewhat difficult because the Ca-PSZ/Al powder mixture was not effectively comminuted. And the Ca ion in Ca-PSZ grains diffused into alumina grains during sintering so that the unstabilization of Ca-PSZ body was occurred which gave the cracks in the specimens. But when MgAl alloy powder was added to monoclinic zirconia, Mg and Al became to oxide at first and subsequently converted to spinel(MgAl2O4) during heating and finally unreacted MgO seemed to stabilize the zirconia. The oxides which formed at the oxidation process would have very fine grain size so that the reaction sintering was more effective to densification and homogeneous microstructure. The mechanical properties of reaction-sintered stabilized zirconia/spinel composite were better than only MgO stabilized zirconia. Sintering behavior in reaction and mechanical properties of sintered body were examined, with emphasis on the relations between spinel formation and mechanical properties.

Study on Mechanical Properties and Toughening Mechanism of MWCNTs/Ti(C, N) Cermets-Based Composites

2013 ◽  
Vol 544 ◽  
pp. 291-294
Author(s):  
Shuo Qi Liu ◽  
Wei Liang Liu
Keyword(s):  
Crystal Structure ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Residual Stress ◽  
Vickers Hardness ◽  
Bending Strength ◽  
Crack Deflection ◽  
Toughening Mechanism ◽  
Hot Pressing Sintering ◽  
Sintering Method

MWCNTs/Ti(C, N) cermets-based composites were prepared by vacuum hot-pressing sintering method. The mechanical properties of samples were examined. XRD and SEM were used to investigate the crystal structure of the composites and microstructure of fractures surface, respectively. The toughening mechanism of composites was discussed particularly. The experimental results showed that the optimum comprehensive mechanical properties of samples were obtained by adding 1wt% MWCNTs in the composites. The bending strength, Vickers hardness and fracture toughness of the composites were 1275.14MPa, 22.75GPa and 10.60MPa•m1/2, respectively, which were improved by 16.89%, 17.15% and 25.59%, respectively, compared to the Ti(C, N)-based cermets without MWCNTs. Bridging and pulling out of MWCNTs, crack deflection, residual stress toughening and micro-voids toughening were attributed to the toughening mechanism of the composites.

Mechanical Properties and Microstructure of Al2O3/(W, Ti)C Nanocomposite

2008 ◽  
Vol 368-372 ◽  
pp. 717-720 ◽  
Author(s):  
Yong Hui Zhou ◽  
Xing Ai ◽  
Jun Zhao ◽  
Xun Liang Yuan ◽  
Qiang Xue
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Sintering Temperature ◽  
Crack Deflection ◽  
Nano Particles ◽  
Nano Scale ◽  
Sintering Time ◽  
Properties Of Materials ◽  
Al2o3 Matrix ◽  
Skeleton Structure

The Al2O3/(W, Ti)C nanocomposite was fabricated by hot pressing technique at 1650-1700°C under 30MPa for 10min. The fracture toughness remarkably increased by adding nano-scale Al2O3 (11vol %) particles into Al2O3 matrix. The flexural strength, fracture toughness and Vickers hardness are 840 MPa, 6.55 MPa•m1/ 2 and 20.1 GPa, respectively. The microstructure of the nanocomposite is homogenous skeleton structure. Nano particles could refine matrix grains and lead to the crack deflection as well as branching and bridging. The coexistence of nano-scale Al2O3, micro-scale Al2O3 and (W, Ti)C can reduce the sintering temperature and sintering time as well as the grain size, and improve the densification and mechanical properties of materials.

Mechanical Properties and Microstructure of Reaction Sintering B4C/SiC Ceramics

2011 ◽  
Vol 66-68 ◽  
pp. 510-515
Author(s):  
Wen Song Lin ◽  
Ning Xiang Fang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Carbon Content ◽  
Sintering Temperature ◽  
Reaction Sintering ◽  
Sic Ceramics ◽  
Compact Pressure ◽  
Optimal Value ◽  
Major Factors

Reaction sintering B4C/SiC ceramics with high density were manufactured. The effect of the carbon content in green bodies on the microstructure and mechanical properties of the ceramics has been studied. Results showed that the carbon content and the value of carbon relative density (ρCRD) in the green bodies were the major factors affected the composition, that is, the free silicon and carbon contents and mechanical behaviors of sintered specimens. The optimal value of ρCRD was gotten at 0.85 g/cm3. The fracture toughness, flexural strength, and hardness of the composites increased with increasing carbon content up to 20 wt.%. The maximum values of fracture toughness of 3.8 MPa∙m1/2, flexural strength of 475 MPa, and hardness of 32.0 GPa were obtained under the following process parameters: value of ρCRD in the green bodies was about 0.85 g/cm3; carbon, B4C and SiC contents in green bodies were 20 wt.%, 30 wt.% and 50 wt.%, respectively; compact pressure was 75 MPa and sintering temperature was 1600°C.

Reaction sintering and mechanical properties of B4C with addition of ZrO2

2000 ◽  
Vol 15 (11) ◽  
pp. 2431-2436 ◽  
Author(s):  
Hae-Won Kim ◽  
Young-Hag Koh ◽  
Hyoun-Ee Kim
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Elevated Temperatures ◽  
Applied Pressure ◽  
Sintering Behavior ◽  
Reaction Sintering ◽  
Densification Behavior ◽  
High Relative Density ◽  
Full Densification

The effect of ZrO2 addition on sintering behavior and mechanical properties of both hot-pressed and pressureless-sintered B4C was investigated. The addition of ZrO2 improved the densification behavior of B4C remarkably via a reaction with the B4C to form ZrB2 at elevated temperatures. When B4C was densified at 2000 °C by hot pressing, only a small amount (approximately 2.5 vol%) of ZrO2 was necessary to achieve a full densification. Excellent mechanical properties (hardness, elastic modulus, flexural strength, and fracture toughness) were observed in those specimens. As the amount of ZrO2 was increased further, the mechanical properties were reduced, except for the fracture toughness, apparently due to the formation of too much ZrB2 in the specimen. Without the applied pressure, larger amounts of ZrO2 should be added to obtain a body with high relative density. When the B4C was sintered at 2175 °C with addition of 10 vol% ZrO2, the specimen has a density higher than 95% of the theoretical, and hardness and flexural strength of 25 GPa and 400 MPa, respectively.

scholarly journals Effect of in situ VSi2 and SiC phases on the sintering behavior and the mechanical properties of HfB2-based composites

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Soheil Ghadami ◽  
Ehsan Taheri-Nassaj ◽  
Hamid Reza Baharvandi ◽  
Farzin Ghadami
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Vickers Hardness ◽  
Thermodynamic Calculations ◽  
Sintering Behavior ◽  
Pressureless Sintering ◽  
Vacuum Atmosphere ◽  
Second Phases ◽  
Microstructural Studies

Abstract In situ HfB2–SiC–VSi2 composite was fabricated by reactive pressureless sintering at the temperature of 2150 °C for 4 h under a vacuum atmosphere. In situ SiC and VSi2 reinforcements were formed using VC and Si powders as starting materials according to the following reaction: VC + 3Si = SiC + VSi2. Microstructural studies and thermodynamic calculations revealed that in situ VSi2 and SiC phases were mostly formed and homogeneously distributed in HfB2 skeleton. The results showed that the density of in situ HfB2–SiC–VSi2 composite was 98%. Besides, the mechanical properties of the composite were effectively enhanced by the formation of in situ second phases. The Vickers hardness and the fracture toughness of the composite reached 20.1 GPa and 5.8 MPa m−1/2, respectively.

Microstructures and Mechanical Properties of Ti3SiC2/Al2O3 and Ti3SiC2-TiC/Al2O3 Composite Ceramics by Modifying Al2O3 Content Via in-situ Synthesized

2020 ◽  
Author(s):  
Jun Ji ◽  
Xuye Wang ◽  
Jinman Yu ◽  
Qinggang Li ◽  
Zhi Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Raw Materials ◽  
Crack Deflection ◽  
Al2o3 Content ◽  
Composite Ceramics ◽  
Volume Percentage ◽  
Al2o3 Composite ◽  
Microcrack Propagation

Abstract Ti3SiC2/Al2O3 and Ti3SiC2-TiC/Al2O3 composite ceramics with various Al2O3 fractions were prepared by Ti, Si, Al, TiC and Al2O3 powers via in-situ reaction. Al2O3 contents in raw materials could influence the reaction process of Ti3SiC2 generated. It would lead to react completely when the Al2O3 volume percentage between 50% to 70%, otherwise TiC as an impurity would be found. Finally the Ti3SiC2/Al2O3 composites with 54.4 wt% Ti3SiC2, and Ti3SiC2-TiC/Al2O3 composites with 54.7 wt% Ti3SiC2 and 9.2 wt% TiC were fabricated successfully. There were two types of TiC existed in composites, called intragranular and intergranular particles. The Ti3SiC2-TiC/Al2O3 composite ceramics with 9.2 wt% TiC showed the higher mechanical properties than Ti3SiC2/Al2O3 composite. From the analyzing of microcrack propagation paths, the dispersed TiC particles as reinforcement agents would cause significant crack deflection, improving the flexural strength and fracture toughness up to 492 MPa and 7.8 MPa.m1/2 respectively.

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