Microstructure and properties of pressureless sintered ZrC-based materials

2008 ◽  
Vol 23 (7) ◽  
pp. 1882-1889 ◽  
Author(s):  
Laura Silvestroni ◽  
Diletta Sciti
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Flexural Strength ◽  
Room Temperature ◽  
Pressureless Sintering ◽  
Secondary Phases ◽  
Sintering Aid ◽  
Mean Particle Size ◽  
Dense Bodies ◽  
Similar Materials

ZrC-based composites were produced by pressureless sintering thanks to the addition of MoSi2 as sintering aid. After preliminary tests, a baseline ZrC material and two mixed ZrC–HfC and ZrC–ZrB2 composites with 20 vol% MoSi2 were densified at 1900 to 1950 °C reaching final relative densities of 96%–98%. Mean particle size of the dense bodies ranged from 5 to 9 μm. Secondary phases were found to form during sintering, such as SiC and Zr–Mo–Si-based compounds. Room-temperature mechanical properties were in the range of the values reported in the literature for similar materials densified by pressure-assisted techniques. The flexural strength was tested at room temperature, 1200 and 1500 °C.

scholarly journals Sintering Behavior, Microstructure, and Mechanical Properties: A Comparison among Pressureless Sintered Ultra-Refractory Carbides

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
Laura Silvestroni ◽  
Diletta Sciti
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Standard Procedure ◽  
Sintering Behavior ◽  
High Temperature Strength ◽  
Pressureless Sintering ◽  
Secondary Phases ◽  
Sintering Aid ◽  
Final Density ◽  
Room Temperature Strength

Nearly fully dense carbides of zirconium, hafnium, and tantalum were obtained by pressureless sintering at 1950°C with the addition of 5–20 vol% of MoSi2. Increasing the amount of sintering aid, the final density increased too, thanks to the formation of small amounts of liquid phase constituted by M-Mo-Si-O-C, where M is either Zr, Hf, or Ta. The matrices of the composites obtained with the standard procedure showed faceted squared grains; when an ultrasonication step was introduced in the powder treatment, the grains were more rounded and no exaggerated grains growth occurred. Other secondary phases observed in the microstructure were SiC and mixed silicides of the transition metals. Among the three carbides prepared by pressurless sintering, TaC-based composites had the highest mechanical properties at room temperature (strength 590 MPa, Young's modulus 480 GPa, toughness 3.8 MPa·m1/2). HfC-based materials showed the highest sinterability (in terms of final density versus amount of sintering aid) and the highest high-temperature strength (300 MPa at 1500  °C).

Microstructure and Mechanical Properties of Hot-Pressed and Pressureless Sintered WC-Al2O3 Ceramic Composites

1993 ◽  
Vol 327 ◽  
Author(s):  
Hidehiro Endo ◽  
Masanori Ueki
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Composite System ◽  
Ceramic Composites ◽  
Pressureless Sintering ◽  
Sintering Aid ◽  
Al2o3 Ceramic ◽  
Remarkable Improvement

AbstractFully densified WC-A12O3 composites were successfully consolidated by both hot-pressing and pressureless sintering. The optimum hot-pressing condition for the composites was 1700°C for 2h under a pressure of 40MPa. A remarkable improvement in mechanical properties was achieved in the composite system, especially in WC-30 and -70vol%A12O3, compared to the monolithic WC and A12O3 ceramics. The addition of MgO as a sintering aid had a great effect on the properties of the composites. WC-30vol%A12O3 composite with 1.Owt% MgO addition exhibited flexural strength higher than 1000MPa up to 1200°C, fracture toughness; KIC≥7MPa√m, and hardness; HV ≥2450. In pressureless sintering with the addition of MgO as a sintering aid and subsequent HIP treatment, the WC-30vol%A12O3 composite exhibited the flexural strength higher than 900MPa up to 1200°C.

Preparation and Mechanical Properties of ReAl11O18 Ceramics

2014 ◽  
Vol 602-603 ◽  
pp. 345-348
Author(s):  
Jun Dong Zhang ◽  
Ming Hao Fang ◽  
Zhao Hui Huang ◽  
Yan Gai Liu ◽  
Xin Min ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Bulk Density ◽  
Room Temperature ◽  
Pressureless Sintering ◽  
Optimal Temperature ◽  
Flexure Strength ◽  
The Real

In this paper, plate-like ReAl11O18 (Re = La, Pr, Nd) toughened ceramics were prepared by pressureless sintering at 1650 °C for 5 h in air. The bulk densities of the sintered samples were between 4.7 to 5.3g/cm3. The mechanical properties of the ReAl11O18 ceramics were studied systematically at room temperature. The flexure strength and fracture toughness of ReAl11O18 ceramics were 97.5 to 102.7 Mpa and 3.8 to 4.2Mpa.m1/2. The results show that: The optimal temperature to synthesis ReAl11O18 ceramics was 1650 °C; The flexural strength and fracture toughness of the ReAl11O18 ceramics increase with the increasing of its bulk density.

Characterization of Hot-Pressed Silicon Nitride Ceramics with Alkoxide-Derived Oxide Mixtures As the Sintering Aid

1992 ◽  
Vol 287 ◽  
Author(s):  
Y. Sato ◽  
C. Sakurai ◽  
M. Ueki ◽  
K. Sugita
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Weight Ratio ◽  
Sintering Aids ◽  
Sintering Aid ◽  
Oxide Powders ◽  
Nitride Ceramics ◽  
Final Weight ◽  
Alkoxide Method

ABSTRACTA homogeneous mixture of Y2O3, CeO2 and MgO with a final weight ratio of 3:1: 2 was prepared by the alkoxide method. The powder mixture was then added into Si3N4 powder in amounts ranging from 4 to 12 wt%, andconsolidated by hot-pressing. Microstructure and mechanical properties of the sintered bodies were determined and compared to those of materials prepared by the conventional route of mixing the oxide powders as sintering aids individually in essentially same composition. The β-fraction (modification ratio) in same composition was higher in thesintered bodies made through the alkoxide method than those made through the conventional one. The room temperature flexural strength was maximized with 6wt% addition of the alkoxide derived oxide, whereas, 12wt% addition of the total oxide was required to maximize the strength by conventional processing.

Preparation of Nanocrystalline Fe2O3 Powder by Cryomilling with Liquid Nitrogen and its Magnetic Property

2020 ◽  
Vol 993 ◽  
pp. 806-810
Author(s):  
Zhi Wei Zhang ◽  
Bing Wei Luo ◽  
Hai Tao Zhou ◽  
Fen Wang
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Magnetic Property ◽  
Liquid Nitrogen ◽  
Room Temperature ◽  
Single Phase ◽  
Rapid Preparation ◽  
Mean Particle Size ◽  
Milling Temperature ◽  
The Mean

Rapid preparation of nanocrystalline γ-Fe2O3 powder with superparamagnetism was realized by cryomilling commercial Fe2O3 powder using liquid nitrogen. The effects of milling temperature and duration on the grain size, phase and microstructure of the nanocrystalline Fe2O3 powder were analyzed. Magnetic property of the nanocrystalline γ-Fe2O3 powder was also tested by magnetometer at room temperature. The results demonstrate that nanocrystalline γ-Fe2O3 powder with single phase can be prepared rapidly by cryomilling with liquid nitrogen. The mean particle size of γ-Fe2O3 powder can be reduced from 300 nm to 13 nm by cryomilling at −130 °C within 3 hours. The nanocrystalline γ-Fe2O3 powder shows superparamagnetism at room temperature.

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.

Microwave Sintering of Si3N4 Ceramics

1992 ◽  
Vol 269 ◽  
Author(s):  
Jinsong Zhang ◽  
Lihua Cao ◽  
Fei Xia
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Microwave Sintering ◽  
Pressureless Sintering ◽  
Transformation Rate ◽  
Sintering Time ◽  
Si3n4 Ceramics ◽  
Room Temperature Strength ◽  
Better Than

ABSTRACTThe Si3N4 ceramics(91wt%Si3N4+5wt%Y2O3+4wt%Al2O3) of room temperature strength 620--760 MPa and fracture toughness 7 MPa-m½ were prepared by microwave sintering and their microstructure and mechanical properties were studied.The experiment results show that the higher N2 pressure (>4atm) is very necessary for microwave sintering of Si3N4 ceramics; microwave sintering can greatly decrease the sintering temperature to 1500* C, and increase the transformation rate of α to β-Si3N4,and reduce the total sintering time to about 1 hour. The mechanical properties of the Si3N4 ceramics sintered by microwave are better than that by conventional pressureless sintering.

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