scholarly journals Microstructural evolution of h-BN matrix composite ceramics with La-Al-Si-O glass phase during hot-pressed sintering

2020 ◽  
Author(s):  
Baofu Qiu ◽  
Xiaoming Duan ◽  
Zhuo Zhang ◽  
Chen Zhao ◽  
Bo Niu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Elastic Modulus ◽  
Microstructural Evolution ◽  
Glass Phase ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Sintering Process ◽  
Composite Ceramics ◽  
Phase Precipitation

Abstract BN/La-Al-Si-O composite ceramics were fabricated by hot-pressed sintering using h-BN, La2O3, Al2O3 and amorphous SiO2 as the raw materials. The effects of sintering temperature on the microstructural evolution, bulk density, apparent porosity, and mechanical properties of h-BN composite ceramics were investigated. The results indicated that La-Al-Si-O liquid phase was formed during sintering process, which provided an environment for the growth of h-BN grains. With increasing sintering temperature, the cristobalite phase precipitation and h-BN grain growth occurred at the same time, which had the significant influence on the densification and mechanical properties of h-BN composite ceramics. The best mechanical properties of BN/La-Al-Si-O composite ceramics were obtained under sintering temperature of 1700 °C, and the elastic modulus, flexural strength, and fracture toughness were 80.5 GPa, 266.4 MPa and 3.25 MPa·m1/2, respectively.

scholarly journals Microstructural Evolution of H-BN Matrix Composite Ceramics With Amorphous La2O3-Al2O3-SiO2 Glass Phase During Hot Pressing

2020 ◽  
Author(s):  
Baofu Qiu ◽  
Xiaoming Duan ◽  
Zhuo Zhang ◽  
Chen Zhao ◽  
Bo Niu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Microstructural Evolution ◽  
Glass Phase ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Sintering Process ◽  
Hot Press ◽  
Composite Ceramics ◽  
Phase Precipitation ◽  
Hot Press Sintering

Abstract BN-La2O3-Al2O3-SiO2 composite ceramics were fabricated by hot press sintering using h-BN, La2O3, Al2O3 and amorphous SiO2 as the raw materials. The effects of sintering temperature on the microstructural evolution, bulk density, apparent porosity, and mechanical properties of h-BN composite ceramics were investigated. The results indicated that ternary La2O3-Al2O3-SiO2 liquid phase was formed during sintering process, which provided an environment for the growth of h-BN grains. With increasing sintering temperature, the cristobalite phase precipitation and h-BN grain growth occurred at the same time, which had the significant influence on the densification and mechanical properties of h-BN composite ceramics. The best mechanical properties of BN-La2O3-Al2O3-SiO2 composite ceramics were obtained under sintering temperature of 1700 °C, and the elastic modulus, flexural strength, and fracture toughness were 80.5 GPa, 266.4 MPa and 3.25 MPa·m1/2, respectively.

scholarly journals Microstructural evolution of h-BN matrix composite ceramics with La-Al-Si-O glass phase during hot-pressed sintering

2021 ◽  
Author(s):  
Baofu Qiu ◽  
Xiaoming Duan ◽  
Zhuo Zhang ◽  
Chen Zhao ◽  
Bo Niu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Microstructural Evolution ◽  
Glass Phase ◽  
Lanthanum Oxide ◽  
Sintering Temperature ◽  
Hexagonal Boron Nitride ◽  
Raw Materials ◽  
Sintering Process ◽  
Composite Ceramics ◽  
Phase Precipitation

AbstractBN/La-Al-Si-O composite ceramics were fabricated by hot-pressed sintering using hexagonal boron nitride (h-BN), lanthanum oxide (La2O3), aluminia (Al2O3), and amorphous silica (SiO2) as the raw materials. The effects of sintering temperature on microstructural evolution, bulk density, apparent porosity, and mechanical properties of the h-BN composite ceramics were investigated. The results indicated that La-Al-Si-O liquid phase was formed during sintering process, which provided an environment for the growth of h-BN grains. With increasing sintering temperature, the cristobalite phase precipitation and h-BN grain growth occurred at the same time, which had a significant influence on the densification and mechanical properties of h-BN composite ceramics. The best mechanical properties of BN/La-Al-Si-O composite ceramics were obtained under the sintering temperature of 1700 °C. The elastic modulus, flexural strength, and fracture toughness were 80.5 GPa, 266.4 MPa, and 3.25 MPa·m1/2, respectively.

Si3N4/BN Composite Ceramics with Nd2O3-Al2O3-Y2O3 Ternary Additives by Pressureless Sintering

2010 ◽  
Vol 434-435 ◽  
pp. 106-108
Author(s):  
Ping Liu ◽  
Yong Feng Li ◽  
Xiang Dong Wang ◽  
Hai Yun Jin ◽  
Guan Jun Qiao
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Transformation ◽  
Flexural Strength ◽  
Pressureless Sintering ◽  
Sintering Process ◽  
Composite Ceramics ◽  
Fracture Toughness Testing ◽  
Β Phase ◽  
Toughness Testing

Si3N4/BN composite ceramics with 25vol% h-BN were prepared by pressure-less sintering process with Nd2O3/Al2O3/Y2O3 as sintering additives. The effects of these ternary additives on the densification behaviors and mechanical properties were investigated. XRD and FESEM were used to investigate the α-β phase transformation and microstructure. The XRD results showed that α-Si3N4 has transformed to β-Si3N4 completely in all the samples during the pressureless sintering process. The line shrinkage increased with the Nd2O3 contents increasing, and the highest line shrinkage (7.75%) was observed when 4wt% Nd2O3 was added, then decreased. The same trends were observed in flexural strength and fracture toughness testing. The ternary additives of Y2O3-Al2O3-Nd2O3 could improve the density, strength and fracture toughness of the material effectively.

Study on Mechanical Property of Al2O3-Based Composite Ceramics Liner of Heavy-Medium Cyclone

2011 ◽  
Vol 295-297 ◽  
pp. 581-584
Author(s):  
Li Qiang Zhang ◽  
Ping Huo ◽  
Yong Huang ◽  
Peng Li ◽  
Rong Yang
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Mechanical Property ◽  
Scanning Electron Microscopy ◽  
Particle Size ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Composite Ceramics ◽  
Heavy Medium ◽  
Scanning Electron

In laboratory condition, industrial zirconia and alumina were used as raw materials, whose particle size was controlled by ultrafine treatment of mechanical milling. The effects of different firing temperatures and soaking times on mechanical properties of Al2O3-based composite ceramics liner were researched. And the microstructure of samples was studied by scanning electron microscopy (SEM). The results indicate that mechanical properties of samples kept 3 h at sintering temperature of 1600°C with adding 30 wt% zirconia are the best.

scholarly journals Microstructural evolution and mechanical properties of in situ nano Ta4HfC5 reinforced SiBCN composite ceramics

2020 ◽  
Vol 9 (6) ◽  
pp. 739-748
Author(s):  
Bingzhu Wang ◽  
Daxin Li ◽  
Zhihua Yang ◽  
Dechang Jia ◽  
Jingyi Guan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Microstructural Evolution ◽  
Hot Pressing ◽  
Raw Materials ◽  
Hybrid Structure ◽  
Second Step ◽  
Composite Ceramics ◽  
Hot Pressing Sintering ◽  
Reactive Hot Pressing

AbstractThe in situ nano Ta4HfC5 reinforced SiBCN-Ta4HfC5 composite ceramics were prepared by a combination of two-step mechanical alloying and reactive hot-pressing sintering. The microstructural evolution and mechanical properties of the resulting SiBCN-Ta4HfC5 were studied. After the first-step milling of 30 h, the raw materials of TaC and HfC underwent crushing, cold sintering, and short-range interdiffusion to finally obtain the high pure nano Ta4HfC5. A hybrid structure of amorphous SiBCN and nano Ta4HfC5 was obtained by adopting a second-step ball-milling. After reactive hot-pressing sintering, amorphous SiBCN has crystallized to 3C-SiC, 6H-SiC, and turbostratic BN(C) phases and Ta4HfC5 retained the form of the nanostructure. With the in situ generations of 2.5 wt% Ta4HfC5, Ta4HfC5 is preferentially distributed within the turbostratic BN(C); however, as Ta4HfC5 content further raised to 10 wt%, it mainly distributed in the grain-boundary of BN(C) and SiC. The introduction of Ta4HfC5 nanocrystals can effectively improve the flexural strength and fracture toughness of SiBCN ceramics, reaching to 344.1 MPa and 4.52 MPa·m1/2, respectively. This work has solved the problems of uneven distribution of ultra-high temperature phases in the ceramic matrix, which is beneficial to the real applications of SiBCN ceramics.

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.

scholarly journals Microstructural evolution and mechanical properties of in situ nano Ta4HfC5 reinforced SiBCN composite ceramics

2020 ◽  
Author(s):  
Bingzhu Wang ◽  
Li Daxin ◽  
Zhihua Yang ◽  
Dechang Jia ◽  
Jingyi Guan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Microstructural Evolution ◽  
Hot Pressing ◽  
Raw Materials ◽  
Hybrid Structure ◽  
Composite Ceramics ◽  
Nano Structure ◽  
Hot Pressing Sintering ◽  
Reactive Hot Pressing

Abstract In this paper, the in situ nano Ta 4 HfC 5 reinforced SiBCN-Ta 4 HfC 5 composite ceramics were prepared by a combination of two-step mechanical alloying and reactive hot-pressing sintering. The microstructural evolution and mechanical properties of the SiBCN-Ha 4 HfC 5 were studied. After the first-step milling of 30 h, the raw materials of TaC and HfC undergone crushing, cold sintering and short-range interdiffusion to finally obtain the high pure nano Ta 4 HfC 5 . A hybrid structure of amorphous SiBCN and nano Ta 4 HfC 5 was obtained by adopting a second-step ball-milling. After reactive hot-pressing sintering, amorphous SiBCN has crystallized to nano SiC and turbostratic BN(C) phases while Ta 4 HfC 5 retained the form of nano structure. With the in situ generation of 2.5 wt% Ta 4 HfC 5 , Ta 4 HfC 5 is preferentially distributed within the turbostratic BN(C); however, as Ta 4 HfC 5 content further raised to 10 wt%, it mainly distributed in the grain-boundary of BN(C) and SiC. The introduction of Ta 4 HfC 5 nanocrystals can effectively improve the flexural strength and fracture toughness of SiBCN ceramics, reaching to 344.1 MPa and 4.52 MPa•m 1/2 , respectively.

Effect of Sintering Pressure on Mechanical Properties of BN-Si3N4 Ceramic Composites Prepared by Spark Plasma Sintering

2016 ◽  
Vol 697 ◽  
pp. 188-192
Author(s):  
Jia Xin An ◽  
Wen Dong Xue ◽  
Feng Rui Zhai ◽  
Ruo Meng Xu ◽  
Jia Lin Sun
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Relative Density ◽  
Spark Plasma Sintering ◽  
Bending Strength ◽  
Raw Materials ◽  
Ceramic Composites ◽  
Composite Ceramics ◽  
Plasma Sintering ◽  
Spark Plasma

BN-Si3N4 composite ceramic wave-transparent materials with excellent mechanical properties were prepared by spark plasma sintering (SPS) using h-BN and α-Si3N4 powders as raw materials, Al2O3 and Y2O3 as sintering aids. The influence of sintering pressure on density and mechanical properties of BN-Si3N4 composite ceramics were studied. The phases were observed by X-ray diffraction (XRD), and the microstructures were identified by scanning electron microscopy (SEM). The results showed that with the sintering pressure increases, the relative density, bending strength and fracture toughness of the composite ceramics were significantly increased, and the porosity decreased rapidly. The effects of pressure on the properties of the composite ceramics was not significant at >40MPa, so 40MPa is optimal for the composite ceramics to gain good overall performance, i.e. the relative density was 89.1%, the porosity was 2.3%, the bending strength reached 215.4 MPa, and the fracture toughness was 3.1/MPa·m1/2.

Effect of Particle Size and Vacuum Sintering Temperature on Phase Composition and Mechanical Properties of WC-12 wt% Co Hardmetals

2012 ◽  
Vol 531-532 ◽  
pp. 3-7
Author(s):  
Shih Hsien Chang ◽  
Chung Wei Lee ◽  
Kuo Tsung Huang ◽  
Ming Wei Wu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Particle Size ◽  
Relative Density ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
Sintering Process ◽  
Vacuum Sintering ◽  
Brittle Phase ◽  
Effect Of Particle Size

The experimental results indicated that the WC-12wt% Co specimens showed excellent mechanical properties and microstructure by the optimal sintering process. The G5 specimen sintered at 1400°C/1 h achieved a relative density of 98% and a hardness of HRA 88.5. Meanwhile, the TRS increased to 2400 MPa. F12 specimens that sintered at 1350°C/1 h achieved a relative density of 99% and a hardness of HRA 92.5. The TRS was also enhanced to 2170 MPa. In this study, the η phase (Co3W3C) precipitated at a high sintering temperature. The precipitations generated by liquid phase sintering gathered in some specific regions of the specimens and reacted with the WC particles. In addition, Co3W3C was a hard and brittle phase that resulted in a low TRS for the specimens; and a large amount of η phases were detrimental to the fracture toughness of the specimens.

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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