scholarly journals Effects of directly added or reaction formed TiB2 on the microstructure and mechanical properties of pressureless-sintered B4C–TiB2 composites

2020 ◽  
Author(s):  
Zongjia Li ◽  
Yangwei Wang ◽  
Huanwu Cheng ◽  
Yu Zhu ◽  
Rui An ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Boron Carbide ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Submicron Particles ◽  
Matrix Composites ◽  
Effective Role ◽  
Carbide Matrix ◽  
Sintering Method

Abstract The boron carbide matrix composites containing boron carbide (B 4 C), titanium diboride (TiB 2 ; 20 wt% and 30 wt%) and titanium carbide (TiC) were fabricated at 2130 °C using the pressureless sintering method. Different amounts of TiB 2 and TiC particles were added to B 4 C, and the TiB 2 content was chosen as the main variable to study the effect on the composites. The density, hardness, bending strength and fracture toughness measurements were performed to obtain the physical and mechanical properties of the samples. The obtained results indicate that by adding 30 wt% TiB 2 submicron particles at 2130 °C, the bending strength and fracture toughness of 277.6 MPa and 5.38 MPa·m 1/2 are obtained for the composite. The particle pullout and crack microbridging play an effective role in toughening the composite ceramics. The main toughening mechanisms of the B 4 C-TiB 2 composites are noted to be microcrack and crack deflection toughening owing to the residual stresses resulting from the mismatch of the thermal expansion coefficient between TiB 2 and B 4 C.

Fabrication of Carbon Nanotube Reinforced Boron Carbide Composite by Hot-Pressing Following Extrusion Molding

2014 ◽  
Vol 616 ◽  
pp. 27-31 ◽  
Author(s):  
Tomohiro Kobayashi ◽  
Katsumi Yoshida ◽  
Toyohiko Yano
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Elastic Modulus ◽  
Carbon Nanotube ◽  
Boron Carbide ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Bending Strength ◽  
Extrusion Direction ◽  
Sem Observation

The CNT/B4C composite with Al2O3 additive was fabricated by hot-pressing following extrusion molding of a CNT/B4C paste, and mechanical properties of the obtained composite were investigated. Many CNTs in the composite aligned along the extrusion direction from SEM observation. 3-points bending strength of the composite was slightly lower than that of the monolithic B4C. Elastic modulus and Vickers hardness of the composite drastically decreased with CNT addition. Fracture toughness of the composite was higher than that of the monolithic B4C.

scholarly journals Bending strength and reliability of porcelains used in all-ceramic dental restorations

Cerâmica ◽  
2018 ◽  
Vol 64 (372) ◽  
pp. 491-497
Author(s):  
A. A. de Almeida Junior ◽  
G. L. Adabo ◽  
B. R. Galvão ◽  
D. Longhini ◽  
B. G. Simba ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Weibull Modulus ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Weibull Analysis ◽  
Specific Group ◽  
Dental Restorations ◽  
Residual Amorphous Phase ◽  
All Ceramic

Abstract Four dental porcelains for covering zirconia were sintered (fired) at 910-960 °C and characterized, focusing in analyzing reliability, physical and mechanical properties. Samples with relative density close to 99% presented leucite crystallization apart from residual amorphous phase. Hardness between 491±23 and 575±32 HV was different among all ceramics. Fracture toughness between 1.13±0.11 and 1.42±0.25 MPa.m1/2 was statistically different. Bending strength results were not different for three porcelain groups (73±9 to 75±12 MPa), with the exception of one specific group (62±4 MPa). Weibull analysis indicated bending strength between 73 and 75 MPa, Weibull modulus (m) between 5.7 and 7.1, while the ceramic with strength of 60 MPa presented m=13.6. The use of classical theory of fracture mechanics associated to the results of properties obtained in this work indicated the critical failure size in these ceramics lays between 65 and 90 μm and the theoretical fracture energy of porcelains is approximately from 10.5 to 16.3 J/m. It was concluded that the porcelains had different behavior, and it seems that there is no clear relationship among the studied properties.

Mechanical Properties and Microstructure of Boron Carbide-Cerium Boride Composite

2012 ◽  
Vol 482-484 ◽  
pp. 1551-1555
Author(s):  
Ke Wu Peng ◽  
Nian Wen Pu ◽  
He Li Ma ◽  
Ren Chen ◽  
Yan Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Boron Carbide ◽  
Fracture Mode ◽  
Main Fracture ◽  
Sintering Method

The mechanical properties of B4C-CeB6 composite prepared by hot pressed sintering method were tested. The study shows: the hardness of B4C-CeB6 composite increases with the content of cerium boride. When the content of the cerium boride is 4wt%, the hardness reaches its supreme value of 31.98Gpa，its hardness is improved nearly 21.09% compared to monolithic boron carbide. The content of the cerium boride does not affect greatly on flexibility strength. However，it gives much effect on fracture toughness. When the content of the cerium boride is 4wt%, the fracture toughness reaches its supreme value of 5.06MPa.m1/2, which is improved nearly 37.5% compared to monolithic boron carbide materials. The main fracture way of B4C-CeB6 composite is intercrystalline rupture, while the transcrystalline rupture is minor. It appears that this change of fracture mode gives rise to the improvement of the fracture toughness.

scholarly journals Effect of Ti Addition on the Microstructure and Mechanical Properties of SiC Matrix Composites Infiltrated by Al–Si (10 wt.%)–xTi Alloy

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 318
Author(s):  
Yajun Yu ◽  
An Du ◽  
Xue Zhao ◽  
Yongzhe Fan ◽  
Ruina Ma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Intermetallic Compounds ◽  
Bending Strength ◽  
Al Alloys ◽  
Al Alloy ◽  
Matrix Composites ◽  
Sic Ceramics ◽  
Microstructure And Mechanical Properties ◽  
Ti Addition

This paper proposes a simple reactive melt infiltration process to improve the mechanical properties of silicon carbide (SiC) ceramics. SiC matrix composites were infiltrated by Al–Si (10 wt.%)–xTi melts at 900 °C for 4 h. The effects of Ti addition on the microstructure and mechanical properties of the composites were investigated. The results showed that the three-point bending strength, fracture toughness (by single-edge notched beam test), and fracture toughness (by Vickers indentation method) of the SiC ceramics increased most by 34.3%, 48.5%, and 128.5%, respectively, following an infiltration with the Al–Si (10 wt.%)–Ti (15 wt.%) melt. A distinct white reaction layer mainly containing a Ti3Si(Al)C2 phase was formed on the surface of the composites infiltrated by Al alloys containing Ti. Ti–Al intermetallic compounds were scattered in the inner regions of the composites. With the increase in the Ti content (from 0 to 15 wt.%) in the Al alloy, the relative contents of Ti3Si(Al)C2 and Ti–Al intermetallic compounds increased. Compared with the fabricated composite infiltrated by an Al alloy without Ti, the fabricated composites infiltrated by Al alloys containing Ti showed improved overall mechanical properties owing to formation of higher relative content Ti3Si(Al)C2 phase and small amounts of Ti–Al intermetallic compounds.

Effect of Microstructure and Sintering Temperature on Fabrication of NITE-SiCf/SiC Composite

2007 ◽  
Vol 345-346 ◽  
pp. 1229-1232 ◽  
Author(s):  
Young Ju Lee ◽  
Han Ki Yoon
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
High Performance ◽  
Composite System ◽  
Matrix Composites ◽  
Practical Applications ◽  
Sic Fiber ◽  
Carbide Matrix ◽  
Sic Composites

Silicon carbide fiber-reinforced silicon carbide matrix composites (SiCf/SiC composites) are attractive materials for use in the blankets and divertors of fusion reactors due to their excellent thermo-mechanical properties and inherently low induced radioactivation. However, the brittle characteristics of SiC such as low fracture toughness and low strain-to fracture impose a severe limitation on the practical applications of SiC materials. SiCf/SiC composites can be considered as a promising candidate in various structural materials, because of their good fracture toughness. In this composite system, the direction of SiC fiber will give an effect to the mechanical properties such as fracture toughness and tensile strength. Therefore, it is important to control a proper direction of SiC fiber for the fabrication of high performance SiCf/SiC composites. .

Effects of CeO2 Addition on Mechanical Properties of LaB6/B4C Composites

2014 ◽  
Vol 887-888 ◽  
pp. 17-20
Author(s):  
Jia Meng Guo ◽  
Lei Yi ◽  
Ke Wu Peng ◽  
He Li Ma ◽  
Ren Chen
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Composite Material ◽  
Boron Carbide ◽  
Sintering Aid ◽  
Main Fracture ◽  
Sintering Method

The properties of CeO2-LaB6/B4C composite material prepared by hot pressed sintering method was tested, CeO2as a sintering aid for boron carbide is investigated in this paper. The study shows: the hardness of CeO2-LaB6/B4C composite increases with the content of CeO2. The density, hardness, flexibility strength and the fracture toughness of LaB6/B4C composites is greatly improved compared by CeO2additive. When the content of the CeO2is 1wt%, LaB6/B4C composite has its the best mechanical properties. The density reaches its supreme value of 2.676 g/cm3, the hardness reaches its supreme value of 39.19 GPa, the flexibility strength reaches its supreme value of 354.15 MPa and the fracture toughness reaches its supreme value of 5.15 MPa.m1/2. In conclusion, the density, hardness and flexibility strength of LaB6/B4C composite is improved by CeO2additive. However,it gives little effect on fracture toughness of LaB6/B4C composite. The main fracture way of CeO2-LaB6/B4C composite material is intercrystalline rupture, while the transcrystalline rupture is minor.

Preparation of Pigmented Glass for Infiltration and Investigation of its Physical and Mechanical Properties

2012 ◽  
Vol 512-515 ◽  
pp. 1802-1806
Author(s):  
Huai Xiu Lu ◽  
Yuan Fu Yi ◽  
Bin Deng ◽  
Long Quan Shao ◽  
Li Sheng Zhao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
Bending Strength ◽  
Porous Alumina ◽  
Physical And Mechanical Properties ◽  
Alumina Crucible ◽  
Three Point Bending ◽  
Scanning Electron

Aim To explore pigmented glass for infiltration and investigate its physical and mechanical properties. Methods The pigmented glass was prepared by melting glass components in an alumina crucible at 1400°C for 2h. The thermal properties were tested using a Setaram-TGDTA 92 analyzer; three point bending strength and fracture toughness were also tested; the microstructure of the glass was studied using a scanning electron microscope. Results The thermal expansion coefficient over the range 20–600 °C was 6.2 × 10-6 °C -1, Tg was about 690 °C, the density, bending strength, fracture toughness and Vickers hardness were 2.23 g/cm3, 118 MPa, 1.22 MPam1/2, and 7.4 GPa respectively. Conclusion The pigments have no detrimental effects on the physical and mechanical properties; thus the pigmented glass for infiltration has favorable physical and mechanical properties and also good compatibility with presintered porous alumina.

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.

Effect of Pressure on TiB2-Cu Composite via In-Situ Reaction Synthesis

2007 ◽  
Vol 280-283 ◽  
pp. 1437-1440
Author(s):  
Yue Feng Sun ◽  
Qiang Xu ◽  
Xing Hong Zhang ◽  
Jie Cai Han ◽  
Jin Huai Liu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Bending Strength ◽  
Exothermic Reaction ◽  
Applied Pressure ◽  
Reaction Synthesis ◽  
Matrix Composites ◽  
Copper Powders ◽  
Fine Microstructure

TiB2-Cu matrix composites from titanium, boron and copper powders were in-situ fabricated by exothermic reaction. The effect of the applied pressure on the mechanical properties of the composite was investigated. The results showed that when the applied pressure increasing, the relative density, bending strength, fracture toughness and hardness of the composites were on the increase due to the formation of fine microstructure and the improvement of densification with the pressure increasing. The high pressure is beneficial to the better mechanical properties.

Mechanical Properties of Nanostructured Zirconia

2010 ◽  
Vol 660-661 ◽  
pp. 757-761 ◽  
Author(s):  
C.P. Silva ◽  
C. Santos ◽  
Cosme Roberto Moreira Silva
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Bending Strength ◽  
Tetragonal Zirconia ◽  
Physical And Mechanical Properties ◽  
Volumetric Fraction ◽  
Reliability Improvement ◽  
Four Point Bending ◽  
Dental Applications

In this work itria stabilized ZrO2 based ceramics for dental applications has been sintered and characterized in terms of physical and mechanical properties. Nanostructured blocks were sintered at 1400 0C and microstrutured blocks sintered at 1600 0C. Both nanostructured and microstructured materials were characterized in terms of densification, crystalline phases, mechanical properties and microstructure. Fracture toughness and four point bending strength were evaluated and compared. For the nanostructured zirconia, the reduced grain size allowed the increase of its toughening capacity, generated from maximization of volumetric fraction of retained tetragonal zirconia particles. For this material higher bending flexural strength is related to induced nucleation of microcracks, increase of energy absorption during crack propagation and developed compressive surface stress. The fracture toughness obtained at nanostructured samples sintered at 1400 0C is approximately 20% higher when compared to microstrucutured samples. These results represent the toughening ability of nanostructured zirconia, originated from higher amount of retained tetragonal phase and grain boundary microcracks. The higher Weibull moduli in this case are indicative of material reliability improvement and these results are correlated to grain size and its influence at mechanical strength.

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