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.

Mechanical Properties of La2O3-Al2O3 Ceramics Prepared by Microwave Sintering

2012 ◽  
Vol 519 ◽  
pp. 265-268 ◽  
Author(s):  
Yun Long Ai ◽  
Fei He ◽  
Bing Liang Liang ◽  
Wen He ◽  
Wei Hua Chen
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Draw Ratio ◽  
Sintering Temperature ◽  
Microwave Sintering ◽  
Microwave Energy ◽  
Pure Alumina ◽  
Sintering Time ◽  
Microstructure Evaluation ◽  
Columnar Grains

The influence of La2O3 on the phase and microstructure evaluation and mechanical properties of La2O3-Al2O3 ceramics sintered with 2.45 GHz microwave energy was investigated. The results showed that La2O3 could densify the pure alumina with a lower sintering temperature and a short sintering time. La2O3 reacted with Al2O3 to form LaAl11O18 completely and the amount of LaAl11O18 increased with the increasing content of La2O3, distributing at the Al2O3 grain boundaries. The specimen doped with 10 vol.% and 15 vol.% La2O3 sintered at 1500 °C exhibited plenty of columnar grains with draw ratio about 1:4. The existence of columnar grains enhanced the microhardness and fracture toughness of La2O3-Al2O3 ceramics.

scholarly journals Effects of Microwave Sintering Temperature and Holding Time on Mechanical Properties and Microstructure of Si3N4/n-SiC ceramics

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3837 ◽  
Author(s):  
Li Qiao ◽  
Zhenhua Wang ◽  
Taiyi Lu ◽  
Juntang Yuan
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Formation ◽  
Mechanical Performance ◽  
Sintering Temperature ◽  
Microwave Sintering ◽  
Holding Time ◽  
Sic Ceramics ◽  
Si3n4 Ceramics

The n-SiC (nanometer SiC) is added to be the additive in order to improve the mechanical performance of Si3N4 ceramics. A microwave sintered the ceramics at different temperature and holding times. The results shows that the Si3N4/n-SiC ceramics (85 wt% Si3N4 + 5 wt% n-SiC + 5 wt% Al2O3 + 5 wt% Y2O3) have the best mechanical properties at 1600 °C, which is beneficial to the densification and β-Si3N4 phase formation for 10 min: the density, hardness, and fracture toughness were 97.1%, 14.44 GPa, and 7.77 MPa·m1/2, which increased by 2.8%, 7.0%, and 13.1%, respectively, when compared with the ceramics (90 wt% Si3N4 + 5 wt% Al2O3 + 5 wt% Y2O3).

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).

Mechanical Properties of Nb2O5-Al2O3 Ceramics Prepared by Microwave Sintering

2011 ◽  
Vol 338 ◽  
pp. 120-123 ◽  
Author(s):  
Yun Long Ai ◽  
Fei He ◽  
Bing Liang Liang ◽  
Wen He ◽  
Wei Hua Chen
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Draw Ratio ◽  
Sintering Temperature ◽  
Microwave Sintering ◽  
Microwave Energy ◽  
Pure Alumina ◽  
Sintering Time ◽  
Microstructure Evaluation ◽  
Columnar Grains

The influence of Nb2O5 on the phase and microstructure evaluation and mechanical properties of Nb2O5-Al2O3 ceramics sintered with 2.45 GHz microwave energy was investigated. The results showed that Nb2O5 could densify the pure alumina with a lower sintering temperature and a short sintering time. Nb2O5 reacted with Al2O3 to form AlNbO4 completely and the amount of AlNbO4 increased with the increasing content of Nb2O5, distributing at the Al2O3 grain boundaries. The specimen doped with 10 vol.% Nb2O5 sintered at 1500 °C exhibited plenty of columnar grains with draw ratio about 1:3. The existence of columnar grains enhanced the microhardness and fracture toughness of Nb2O5-Al2O3 ceramics.

Effect of Nb2O5/La2O3 Additions on Mechanical Properties of Al2O3 Ceramics Prepared by Microwave Sintering

2013 ◽  
Vol 544 ◽  
pp. 281-285 ◽  
Author(s):  
Yun Long Ai ◽  
Nan Jiang ◽  
Fei He ◽  
Bing Liang Liang ◽  
Wen He
Keyword(s):  
Mechanical Properties ◽  
Draw Ratio ◽  
Sintering Temperature ◽  
Microwave Sintering ◽  
Microwave Energy ◽  
Composite Ceramics ◽  
Pure Alumina ◽  
Sintering Time ◽  
Microstructure Evaluation ◽  
Columnar Grains

The influence of Nb2O5 and La2O3 on the phase and microstructure evaluation and mechanical properties of composite ceramics sintered with 2.45 GHz microwave energy was investigated. The results showed that Nb2O5 could densify the pure alumina with a lower sintering temperature and a short sintering time. Nb2O5 reacted with Al2O3 to form AlNbO4 completely and the amount of AlNbO4 increased with the increasing content of Nb2O5, distributing at the Al2O3 grain boundaries. The specimen doped with 10 Vol.% Nb2O5 sintered at 1500 °C exhibited plenty of columnar grains with draw ratio about 1:3. La2O3 reacted with Al2O3 to form LaAl11O18 completely, the specimen doped with 10 Vol.% and 15 Vol.% La2O3 sintered at 1500 °C exhibited plenty of columnar grains with draw ratio about 1:4. The existence of columnar grains enhanced the microhardness and fracture toughness of composite ceramics.

scholarly journals Microwave Sintering and Microwave Dielectric Properties of (1–x)Ca0.61La0.26TiO3-xNd(Mg0.5Ti0.5)O3 Ceramics

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 438
Author(s):  
Shuwei Yang ◽  
Bingliang Liang ◽  
Changhong Liu ◽  
Jin Liu ◽  
Caisheng Fang ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Mobile Communications ◽  
Sintering Temperature ◽  
Microwave Sintering ◽  
Microwave Dielectric Properties ◽  
Conventional Heating ◽  
Sintering Process ◽  
Microwave Dielectric ◽  
Sintering Time ◽  
Frequency Temperature

The (1–x)Ca0.61La0.26TiO3-xNd(Mg0.5Ti0.5)O3 [(1–x)CLT-xNMT, x = 0.35~0.60] ceramics were prepared via microwave sintering. The effects of sintering temperature and composition on the phase formation, microstructure, and microwave dielectric properties were investigated. The results show that the microwave sintering process requires a lower sintering temperature and shorter sintering time of (1–x)CLT-xNMT ceramics than conventional heating methods. All of the (1–x)CLT-xNMT ceramics possess a single perovskite structure. With the increase of x, the dielectric constant (ε) shows a downward trend; the quality factor (Qf) drops first and then rises significantly; the resonance frequency temperature coefficient (τf) keeps decreasing. With excellent microwave dielectric properties (ε = 51.3, Qf = 13,852 GHz, τf = −1.9 × 10−6/°C), the 0.65CLT-0.35NMT ceramic can be applied to the field of mobile communications.

Effect of TiO2 and MgO on Microstructure of α-Alumina Ceramics and its Sintering Behavior

2015 ◽  
Vol 1112 ◽  
pp. 519-523 ◽  
Author(s):  
Jarot Raharjo ◽  
Sri Rahayu ◽  
Tika Mustika ◽  
Masmui ◽  
Dwi Budiyanto
Keyword(s):  
Mechanical Properties ◽  
Sintering Temperature ◽  
Physical And Mechanical Properties ◽  
Basic Material ◽  
Sintering Behavior ◽  
Pressureless Sintering ◽  
Alumina Ceramics ◽  
Density Measurements ◽  
Technical Alumina ◽  
Platelet Structure

Observation on the effect of adding titanium oxide (TiO2) and magnesium oxide (MgO) on the sintering of α-alumina (Al2O3) has been performed. In this study, technical alumina used as basic material in which the sample is formed by the pressureless sintering/cold press and sintered at 1500°C which is lower than alumina sintering temperature at 1700°C. Elemental analysis, observation of microstructure, hardness, fracture toughness and density measurements were carried out to determine the physical and mechanical properties of alumina. The results indicate a change in the microstructure where the content of the platelet structure are much more than the equilateral structure. At sintering temperature of 1500°C, neck growth occurs at ceramics grain, supported by the results of the density test which indicate perfect compaction has occurred in this process.

Effects of MgO and Y2O3 on the Microstructure and Mechanical Properties of Al2O3 Ceramics

2013 ◽  
Vol 589-590 ◽  
pp. 572-577 ◽  
Author(s):  
Hua He Liu ◽  
Han Lian Liu ◽  
Chuan Zhen Huang ◽  
Bin Zou ◽  
Ya Cong Chai
Keyword(s):  
Mechanical Properties ◽  
Sintering Temperature ◽  
Hot Press ◽  
Composite Ceramics ◽  
Microstructure And Mechanical Properties ◽  
Suitable Amount ◽  
Hot Press Sintering ◽  
Grains Refinement ◽  
Better Than

Al2O3-MgO, Al2O3-Y2O3 and Al2O3-MgO-Y2O3 composite ceramics were fabricated respectively by hot-press sintering technique. With the analysis of the mechanical properties and microstructure, it was found that single additive MgO could be more favorable to the grains’ refinement and densification than Y2O3; the composite additive including both MgO and Y2O3 was better than single additive MgO or Y2O3, because their interactions could improve the mechanical properties of the Al2O3 ceramics; The sintering temperature could be reduced by adding the suitable amount of composite additives.

scholarly journals Synthesis of "in situ" reinforced silicon nitride composites

2004 ◽  
Vol 69 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Aleksandra Vuckovic ◽  
Snezana Boskovic ◽  
Ljiljana Zivkovic
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Nitride ◽  
Pressureless Sintering ◽  
Sintering Additives ◽  
Sintering Time

The objective of this work was to investigate the effect of two different sintering additives (CeO2 and Y2O3 + Al2O3), sintering time and amount of ?-Si3N4 seeds on the densification, mechanical properties and microstructure of self-reinforced Si3N4 based composites obtained by pressureless sintering. Preparation of ?-Si3N4 seeds, also obtained by a pressureless sintering procedure, is described. Samples without seeds were prepared for comparison. The results imply that self-reinforced silicon nitride based composites with densities close to the theoretical values and with fracture toughness of 9.3MPa m1/2 can be obtained using a presureless sintering procedure.

Effects of Sintering Process on the Properties of Ti3SiC2/Cu Composite

2012 ◽  
Vol 512-515 ◽  
pp. 377-381 ◽  
Author(s):  
Jin Rong Lu ◽  
Yang Zhou ◽  
Yong Zheng ◽  
Shi Bo Li ◽  
Zhen Ying Huang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Sintering Temperature ◽  
Sintering Process ◽  
Vacuum Sintering ◽  
New Type ◽  
Sintering Conditions ◽  
The Relationship ◽  
Better Than

In this paper, a new type of Ti3SiC2/Cu composites with the volume fractions of 30% Ti3SiC2 particle was prepared by hot pressing and vacuum sintering respectively. The effects of sintering temperature and holding time on the density, resistance and Vickers hardness of Cu-30vol%Ti3SiC2 composite were investigated. The results show that the mechanical properties of the composites prepared by hot pressing are better than that prepared by vacuum sintering. The relative densities of Cu-30vol% Ti3SiC2 composites are rather high in suitable sintering conditions. It achieved 100% for the composites prepared by hot pressing at 930°C for 2h, and 98.4% for the composites prepared by vacuum sintering at 1250°C for 1h. At the same time, the maximum Vickers hardness reached 1735MPa at 900°C by hot pressing. The resistance and Vickers hardness of the composites decreased with an increase in sintering temperature, whereas the density increased. Scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) were used to observe the microstructure of the composites. The relationship between microstructure and mechanical properties was discussed.

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