Self-reinforced Y-α-sialon ceramics with barium.aluminosilicate as an additive

2003 ◽  
Vol 18 (10) ◽  
pp. 2446-2450 ◽  
Author(s):  
Feng Ye ◽  
Mikio Iwasa ◽  
Caili Su ◽  
Sheng Chen
Keyword(s):  
Heat Treatment ◽  
Liquid Phase ◽  
Flexural Strength ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Liquid Phase Sintering ◽  
Post Heat Treatment ◽  
Sintering Aid ◽  
Barium Aluminosilicate

Y-α-sialons (Y0.333Si10Al2ON15) were prepared by hot pressing using 5 wt.% BaAl2Si2O8 as an additive. The results showed that barium aluminosilicate not only.served as a liquid-phase sintering aid to promote densification, but also facilitated the.development of elongated α-sialon grains. The obtained self-toughened α-sialon was.both hard and tough. The Vickers hardness, flexural strength, and fracture toughness.are 18.9 GPa, 802 MPa, and 6.0 Mpam1/2, respectively. Post heat treatment could.promote the growth of elongated α-sialon grains, hence further increasing its.toughness.

Strength Degradation Flaws in the Liquid-Phase-Sintered SiC Based Ceramics

2009 ◽  
Vol 409 ◽  
pp. 350-353
Author(s):  
Alexandra Kovalčíková ◽  
Ján Dusza ◽  
Pavol Šajgalík
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
Liquid Phase ◽  
Flexural Strength ◽  
Crack Deflection ◽  
Liquid Phase Sintering ◽  
Crack Branching ◽  
Mechanical Interlocking ◽  
Heat Treated

The effect of the heat treatment on the fracture toughness and flexural strength of the silicon carbide – silicon nitride composites prepared by liquid-phase-sintering was investigated. The results were compared to those obtained for a reference silicon carbide material, prepared by the same fabrication route. The fracture toughness increased from 3.19 to 5.15 MPa.m1/2 due to the toughening mechanisms (crack deflection, mechanical interlocking, crack branching) occurring in the heat treated materials during the crack propagation. However, the flexural strength decreased after the heat treatment of the experimental materials. The strength of the investigated materials was degraded by the presence of processing flaws mainly in the form of pores, clusters of pores, and SiC agglomerates.

The Effect of TiC on the Liquid Phase Sintering of SiC Ceramics with Al2O3 and Y2O3 Additives

2014 ◽  
Vol 602-603 ◽  
pp. 197-201 ◽  
Author(s):  
Han Qin Liang ◽  
Xiu Min Yao ◽  
Hui Zhang ◽  
Xue Jian Liu ◽  
Zheng Ren Huang
Keyword(s):  
Solid Solution ◽  
Fracture Toughness ◽  
Liquid Phase ◽  
Flexural Strength ◽  
Uniform Distribution ◽  
Vickers Hardness ◽  
Liquid Phase Sintering ◽  
Homogeneous Microstructure ◽  
Ceramic Phase ◽  
Sic Ceramics

Low fracture toughness of SiC ceramics limits their applications for the low reliability. Inclusion of second ceramic phase improves the toughness of SiC ceramics. In this presentation, SiC ceramics with 5wt% TiC was pressureless liquid phase sintered (LPS) with the additives of Al2O3 and Y2O3 to ~98% theoretical density at the temperature of 1920 °C for 1 hour. The TiC grains were well distributed and good for the uniform distribution of the liquid phase YAG in the SiC matrix, which resulted in the homogeneous microstructure with fine SiC grains. The existence of TiC benefited the formation of elongated α-SiC, which favored the bridging and deflection of cracks so that the fracture toughness was improved to some extent. Because the amount of TiC was so small that the inherent properties of SiC was not degraded. The flexural strength and Vickers hardness maintained similar with the LPS SiC without TiC. The phase compositions detected in the sample were SiC, YAG and TiC. And no solid-solution of SiC and TiC was revealed by the mapping of EDS.

scholarly journals Nano-(Ta, Zr)C Precipitates at Multigrain Conjunctions in TaC Ceramic with 10 mol% ZrC and 5 mol% Cu as Sintering Aid

2018 ◽  
Vol 2018 ◽  
pp. 1-5
Author(s):  
Lianbing Zhong ◽  
Guihong Geng ◽  
Yujin Wang ◽  
Feng Ye ◽  
Limeng Liu
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Glassy Matrix ◽  
Sintering Aid ◽  
Uniform Dispersion ◽  
New Type

A fully dense TaC ceramic was prepared by hot pressing using 10 mol% ZrC plus 5 mol% Cu as a sintering aid. Formation of (Ta, Zr)C solid solution (ss) by reaction between TaC and ZrC facilitated densification. Addition of Cu refined the microstructure and consequently improved flexural strength of the TaC ceramics. TEM investigation found ubiquitous precipitation of nanocrystallites at multigrain conjunctions. The nanocrystallites were (Ta, Zr)C solid solution with uniform dispersion in an oxygen-rich glassy matrix. Although formation of nanoprecipitates may not much affect the mechanical properties of the TaC ceramic, the structure suggested a new type of nanoceramic worth further research.

scholarly journals Impact of Morphology and Microstructure on the Mechanical Properties of Ge-As-Pb-Se Glass Ceramics

2020 ◽  
Vol 10 (8) ◽  
pp. 2836 ◽  
Author(s):  
Rashi Sharma ◽  
Rebecca Welch ◽  
Myungkoo Kang ◽  
Claudia Goncalves ◽  
Cesar Blanco ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Vickers Hardness ◽  
Glass Ceramic ◽  
Volume Fraction ◽  
Glass Ceramics ◽  
Post Heat Treatment ◽  
Base Glass ◽  
Parent Glass ◽  
Crystal Phases

The impact of base glass morphology and post heat-treatment protocol on the mechanical properties (Vickers hardness and Young’s modulus) of a multi-component glass-ceramic was examined. Two parent chalcogenide glasses with identical composition but varying morphology (homogeneous and phase separated) were evaluated for their mechanical properties following identical thermal processing to induce crystallization. The nucleation and growth rates of the starting materials were compared for the two glasses, and the resulting crystal phases and phase fractions formed through heat treatment were quantified and related to measured mechanical properties of the glass ceramics. The presence of a Pb-rich amorphous phase with a higher crystal formation tendency in the phase-separated parent glass significantly impacted the volume fraction of the crystal phases formed after heat-treatment. Pb-rich cubic crystal phases were found to be dominant in the resulting glass ceramic, yielding a minor enhancement of the material’s mechanical properties. This was found to be less than a more moderate enhancement of mechanical properties due to the formation of the dominant needle-like As2Se3 crystallites resulting from heat treatment of the homogeneous, commercially melted parent glass. The greater enhancement of both Vickers hardness and modulus in this glass ceramic attributable to the high-volume fraction of anisotropic As2Se3 crystallites in the post heat-treated commercial melt highlights the important role base glass morphology can play on post heat-treatment microstructure.

Microstructure and Properties of Hot-Pressing Sintered Tungsten Carbide Composites by Adding Cubic Boron Nitride

2015 ◽  
Vol 655 ◽  
pp. 45-48
Author(s):  
Kun Li ◽  
Hai Yan Chen ◽  
Qiu Shuang He ◽  
Li Hua Dong
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Flexural Strength ◽  
Tungsten Carbide ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Cubic Boron Nitride ◽  
Microstructure And Mechanical Properties ◽  
Hot Pressing Sintering ◽  
Sintering Method

(0, 5, 10, 15, 20) vol% CBN-WC/Co composites were consolidated by ball milling and the following hot-pressing sintering method. WC, Co and CBN powders were used as the starting materials. The effects of the CBN content on the density, microstructure and mechanical properties of CBN-WC/Co composites were investigated. The results showed that the CBN content had remarkable influence on the microstructure and mechanical properties of CBN-WC/Co Composites. With the increasing content of CBN, the density decrease, while Vickers hardness and flexural strength increased initially to the maximum values and then decreased at CBN 10 vol%. When 10 vol% CBN-WC/Co powders were hot-pressing sintered at 1350°C and 20MPa for 90 min, an excellent Vickers hardness of 19.8GPa was achieved, combining a flexural strength of 682MPa.

Synthesis and Characterization of Ti3(Al1-n Gen)C2 by a Reactive Hot Pressing of TiCx, Al, and Ge Powder Mixture

2007 ◽  
Vol 124-126 ◽  
pp. 751-754 ◽  
Author(s):  
Jae Ho Han ◽  
Kyung Don Nam ◽  
Sang Whan Park ◽  
Young Do Kim
Keyword(s):  
Flexural Strength ◽  
Powder Mixture ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Indentation Load ◽  
Synthesis And Characterization ◽  
Solid Reaction ◽  
Ternary Carbide ◽  
Reactive Hot Pressing

Bulk Ti3(Al1-nGen)C2 (n=0, 0.3, 0.5, 0.7, 1.0)were synthesized by a reactive hot pressing of TiCX (x=0.6), Al and Ge powder mixture at 1400 °C for 1 h under 25 MPa. A series of Ti3(Al1-nGen)C2 was successfully synthesised by a hot pressing through a direct liquid-solid reaction between Al-Ge melt and TiCx, and simultaneous densification. Synthesized bulk Ti3(Al1-nGen)C2 was maintained a typical layered structure as shown in other ternary carbide such as Ti3AlC2 and Ti3GeC2. With increasing Al or Ge contents in Ti3(Al1-nGen)C2, both of Vickers hardness and flexural strength of Ti3(Al1-nGen)C2 were increased compared to those of pure Ti3AlC2 and Ti3GeC2 . The maximum flexural strength of Ti3(Al1-nGen)C2 (n=0.3) was about 600 MPa, which was about 3 times higher than that of pure Ti3GeC2. The Vickers hardnesses of Ti3(Al1-nGen)C2 and Ti3AlC2 were slightly decreased with increasing an indentation load.

Use of Vanadium Oxide as a Liquid Phase Sintering Aid for Barium Hexaferrite

2018 ◽  
Vol 23 (3) ◽  
pp. 409-415 ◽  
Author(s):  
John G. Fisher ◽  
Phan Gia Le ◽  
Hak-Sang Han ◽  
Su-Min Jeong ◽  
Naomi Karina Cabral de Leon ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Vanadium Oxide ◽  
Barium Hexaferrite ◽  
Liquid Phase Sintering ◽  
Sintering Aid

Semiconducting BaTiO3 ceramic prepared by low temperature liquid phase sintering

1998 ◽  
Vol 13 (3) ◽  
pp. 660-664 ◽  
Author(s):  
I. Zajc ◽  
M. Drofenik
Keyword(s):  
Liquid Phase ◽  
Grain Boundary ◽  
Sintering Temperature ◽  
Positive Temperature Coefficient ◽  
Liquid Phase Sintering ◽  
Positive Temperature ◽  
Sintering Aid ◽  
Ptcr Effect ◽  
Temperature Coefficient Of Resistivity ◽  
Temperature Liquid

Donor-doped BaTiO3 ceramics were prepared by adding PbO B2O3 SiO2 as a sintering aid. Semiconducting BaTiO3 was obtained at a sintering temperature of 1100 °C. The sintered samples exhibit the Positive Temperature Coefficient of Resistivity (PTCR) effect, which depends on the amount of liquid phase, the concentration of the donor-dopant, and the sintering temperature. The cold resistivity of the samples decreases when the sintering temperature increases. The increase of the grain boundary resistivity and hence of the cold resistivity at lower sintering temperatures was explained by applying the diffusion grain boundary layer model.

Low-Temperature Sintering and Microwave Dielectric Properties of CaWO4-Mg2SiO4 Ceramics

2014 ◽  
Vol 933 ◽  
pp. 12-16 ◽  
Author(s):  
Chung Long Pan ◽  
Ping Cheng Chen ◽  
Tsu Chung Tan ◽  
Wei Cheng Lin ◽  
Chun Hsu Shen ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Solid State ◽  
Liquid Phase ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Liquid Phase Sintering ◽  
Low Temperature Sintering ◽  
Sintering Aids ◽  
Sintering Aid ◽  
Microwave Dielectric

The effect of V2O5addition on the microstructures and the microwave dielectric properties of 0.9CaWO4-0.1Mg2SiO4(9CWMS) ceramics prepared by conventional solid-state routes have been investigated. The V2O5were selected as liquid phase sintering aids to lower the sintering temperature of 9CWMS ceramics. A small amount of V2O5(0.25~1 wt%) were used for sintering aid and led to high densification at 1050°C. The dielectric properties of 9CWMS ceramics with V2O5additions are strongly dependent on the densification, the microstructure. As the amount of V2O5additives increased from 0.25 to 1.0 wt%, the dielectric constantsεrdecreased following the trend with density. The quality valuesQdecreased with the increase of V2O5amount for all sintering temperatures. The 0.25 wt% V2O5-doped 0.9CaWO4-0.1Mg2SiO4ceramicssintered at 1080°C for 2 h had the optimum dielectric properties: εr= 5.7;Q×f= 73000 (at 14 GHz).

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