scholarly journals Study of the Comparative Effect of Sintering Methods and Sintering Additives on the Microstructure and Performance of Si3N4 Ceramic

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2142 ◽  
Author(s):  
Liangliang Yang ◽  
Allah Ditta ◽  
Bo Feng ◽  
Yue Zhang ◽  
Zhipeng Xie
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Relative Density ◽  
Transition Rate ◽  
Bending Strength ◽  
Si3n4 Ceramic ◽  
Sintering Additives ◽  
The Difference ◽  
And Performance

The Si3N4 ceramics were prepared in this study by gas pressure sintering (GPS) and spark plasma sintering (SPS) techniques, using 5 wt.% Yb2O3–2 wt.% Al2O3 and 5 wt.% CeO2–2 wt.% Al2O3 as sintering additives. Based on the difference in sintering methods and sintering additive systems, the relative density, phase composition, phase transition rate, microstructure, mechanical properties, and thermal conductivity were comparatively investigated and analyzed. SPS proved to be more efficient than GPS, producing higher relative density, bending strength, hardness, and thermal conductivity of Si3N4 ceramic with both additive systems; however, the phase transition rate and fracture toughness were lower. Similarly, higher bending strength, hardness, and thermal conductivity were achieved with Yb2O3–Al2O3 than CeO2–Al2O3 in the case of GPS and SPS, and only the relative density, fracture toughness, and phase transition rate were lower.

Effects of Sintering Additives on the Microstructure and Mechanical Properties of Silicon Nitride Ceramics by GPS

2010 ◽  
Vol 105-106 ◽  
pp. 27-30 ◽  
Author(s):  
Wei Ru Zhang ◽  
Feng Sun ◽  
Ting Yan Tian ◽  
Xiang Hong Teng ◽  
Min Chao Ru ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Transformation ◽  
Silicon Nitride ◽  
Porous Silicon ◽  
Flexural Strength ◽  
Relative Density ◽  
Sintering Additives ◽  
Microstructure And Mechanical Properties ◽  
Nitride Ceramics

Silicon nitride ceramics were prepared by gas pressure sintering (GPS) with different sintering additives, including La2O3, Sm2O3 and Al2O3. Effect of sintering additives on the phase-transformation, microstructure and mechanical properties of porous silicon nitride ceramics was investigated. The results show that the reaction of sintering additives each other and with SiO2 had key effects on the phase-transformation, grain growing and grain boundaries. With 9MPa N2 atmosphere pressure, holding 1h at 1850°C, adding 10wt% one of the La2O3, Sm2O3, Al2O3, porous silicon nitride was prepared and the relative density was 78%, 72%, 85% respectively. The flexural strength was less than 500MPa, and the fracture toughness was less than 4.8MPam1/2. Dropping compounds sintering additives, such as La2O3+Al2O3, Sm2O3+Al2O3 effectively improves the sintering and mechanical properties. The relative density was 99.2% and 98.7% with 10wt% compounds sintering additives. The grain ratio of length to diameter was up to 1:8. The flexural strength was more than 900MPa, and the fracture toughness was more than 8.9MPam1/2.

scholarly journals Preparation and Performance of Al2O3/Ti(C,N)-Added ZrO2 Whisker and NanoCoated CaF2@Al(OH)3 Powder

2020 ◽  
Vol 10 (13) ◽  
pp. 4435
Author(s):  
Qi Li ◽  
Guangchun Xiao ◽  
Zhaoqiang Chen ◽  
Runxin Guo ◽  
Mingdong Yi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Transition ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Ceramic Material ◽  
Microstructure And Mechanical Properties ◽  
And Performance

The Al2O3/Ti(C,N) ceramic material added micron ZrO2 whisker and nano coated CaF2@Al(OH)3 powder was fabricated. The micron ZrO2 whisker was for the toughening and reinforcing phase and the nano coated CaF2@Al(OH)3 powder was the lubricant. For obtaining a ceramic material with optimal comprehensive mechanical properties and friction properties, the influences of different compositions of the ZrO2 whisker and nano coated CaF2@Al(OH)3 powder on the microstructure and mechanical properties were analyzed, respectively. The result demonstrated that as the addition of the ZrO2 whisker was 6 vol% and the addition of the nano coated CaF2@Al(OH)3 powder was 10 vol%, the optimal self-lubricating ceramic material had optimal mechanical properties. The hardness of the ceramic material was 16.72 GPa, the flexural strength was 520 MPa and the fracture toughness reached 7.16 MPa·m1/2. The formation of the intragranular structure, whisker toughening and the phase transition of ZrO2 were the main mechanisms.

Development of a Silicon-Infiltrated Silicon Carbide (SiSiC) Friction Layer by the Doctor-Blade Technique Using a Computer-Optimized Calculation for the Packing Density

2015 ◽  
Vol 825-826 ◽  
pp. 264-270
Author(s):  
Pascal Seffern ◽  
Lee Klein ◽  
Daniel Tischer ◽  
Antje Liersch
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Bending Strength ◽  
Matrix Material ◽  
Particle Packing ◽  
Friction Layer ◽  
Solid Mixture ◽  
Particle Parameter ◽  
Tape Cast

This paper focuses on an iterative algorithm for setting and attaining particle packing densities by means of different concentrations of a matrix material. The mechanical properties of a product, such as fracture toughness, bending strength and thermal conductivity are directly dependent on the amount of matrix material present. A tape cast friction layer was developed, in order to investigate the dependence of the parameters of the RRSB distribution on concentration of matrix material. The results verify the calculation method of a solid mixture and show a linear dependence of the RRSB particle-parameternon the concentration of matrix material (SiC-content).

scholarly journals Effect of particle size of Y2O3-Al2O3 additives on microstructure and mechanical properties of Si3N4 ceramic balls for bearing applications

2021 ◽  
Vol 15 (3) ◽  
pp. 297-305
Author(s):  
Jing Zhang ◽  
Wenxue Wang ◽  
Feng Sun ◽  
Weiru Zhang ◽  
Boheng Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Relative Density ◽  
Si3n4 Ceramic ◽  
Sintering Additives ◽  
Microstructure And Mechanical Properties ◽  
Indentation Fracture Toughness ◽  
Effect Of Particle Size ◽  
Gas Pressure Sintering ◽  
Si3n4 Matrix

Si3N4 ceramic balls were prepared by gas pressure sintering with Y2O3 and Al2O3 as sintering additives. The effects of particle size of Y2O3-Al2O3 additives on densification, microstructure and mechanical properties of Si3N4 ceramic balls were investigated. The reliability of Si3N4 ceramic balls was evaluated through the Weibull modulus. The results showed that Si3N4 ceramic balls containing nanosized Y2O3-Al2O3 additives have a higher relative density and better comprehensivemechanical properties compared with the samples containing microsized additives, with relative density of 98.9 ? 0.2%TD, Vickers hardness of 14.7 ? 0.1GPa, indentation fracture toughness of 6.5 ? 0.1MPa?m1/2 and crushing strength of 254 ? 8.5MPa. The more homogeneous and extensive dispersion of the nanosized sintering additives in the Si3N4 matrix is the main reason for the enhancement in density and mechanical properties of the Si3N4 ceramic balls.

Preparation and Performance of Zirconia Fiber Board

2018 ◽  
Vol 281 ◽  
pp. 912-917
Author(s):  
Liu Shi Tao ◽  
Yu Feng Chen ◽  
Shi Chao Zhang ◽  
Ke Wei Deng ◽  
Hao Ran Sun ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Bending Strength ◽  
Soluble Starch ◽  
Zirconia Powder ◽  
Strength Performance ◽  
Long Time ◽  
Zirconia Fiber ◽  
And Performance ◽  
High Temperature Calcination

Zirconia fiber not only can be used for a long time in 1600°C, but also has low thermal conductivity at high temperature. Due to the excellent insulation performance, it has a broad application prospect in aerospace, aviation, energy and other areas. In the present study, we chose yttrium stabilized zirconia fibers and nanometer zirconia powder as main material and adding soluble starch, zirconium sol as low temperature and high temperature binder. Rigid zirconia fiber board was prepared by material slurry, filter shaping, stripping drying and high temperature calcination. After high temperature calcination of 1600°C for 12h, sample pore are mainly concentrated in 25-75μm, bending strength performance is best when the adding amount of nanometer zirconia powder was 7%, the thermal conductivity is only 0.132 W·m-1·K-1 at 1400°C.

Preparation of the Al2O3/3Y-TZP Ceramics by Microwave Sintering under Low Temperature

2013 ◽  
Vol 477-478 ◽  
pp. 1238-1241
Author(s):  
Jun Ming Luo ◽  
Ji Lin Xu ◽  
Hong Yan Zuo ◽  
Jun Huang
Keyword(s):  
Fracture Toughness ◽  
Low Temperature ◽  
Relative Density ◽  
Bending Strength ◽  
Microwave Sintering ◽  
Spherical Particles ◽  
Ceramic Samples ◽  
Coprecipitation Process

Nanometer Al2O3/3Y-TZP powders were prepared by coprecipitation process and the Al2O3/3Y-TZP ceramics were prepared by microwave sintering under relatively low temperature. The relative density, bending strength and fracture toughness of the Al2O3/3Y-TZP ceramic samples were studied. The results showed that the Al2O3/3Y-TZP powders exhibited fine and homogeneous near-spherical particles with the size of 40-60 nm. With increasing the sintering temperatures, all of the relative density, bending strength and fracture toughness of the ceramic samples increased firstly, reaching the maximum values of 99.1%, 1236 MPa and 10.89 MPa·m1/2at 1250 °C respectively, and then decreased.

Fabrication and Performance of Al-NaI Radioactive Transmutation Targets

2010 ◽  
Vol 150-151 ◽  
pp. 580-587
Author(s):  
Hui Qiang Liu ◽  
Yi Feng ◽  
Xue Bin Zhang ◽  
Bin Li ◽  
Yan Fang Zhu ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Powder Metallurgy ◽  
Energy Spectrum ◽  
Relative Density ◽  
Spectrum Analysis ◽  
Bending Strength ◽  
Aluminum Matrix ◽  
Energy Spectrum Analysis ◽  
And Performance

Al-NaI radioactive transmutation target was prepared by powder metallurgy. The existing way of the phase of target was analyzed by the application of XRD and its microstructure and morphology was observed by SEM. Then EDS was used for micro-area energy spectrum analysis and the property of target with different NaI was measured and compared. The results show that NaI is uniformly distributed within the aluminum matrix. The relative density and bending strength of transmutation targets decrease with the increasing content of NaI. The hardness and electrical resistivity of transmutation targets increase with the increasing content of NaI.

Spark Plasma Sintering of α-Si3N4 Ceramics with MgO-Al2O3 as Sintering Additives

2007 ◽  
Vol 351 ◽  
pp. 176-179 ◽  
Author(s):  
Fa Qiang Yan ◽  
Fei Chen ◽  
Qiang Shen ◽  
Lian Meng Zhang
Keyword(s):  
Relative Density ◽  
Spark Plasma Sintering ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Close Correlation ◽  
Liquid Phase Sintering ◽  
Sintering Additives ◽  
Sintering Mechanism ◽  
Plasma Sintering ◽  
Spark Plasma

In the present study, α-Si3N4 is prepared by using MgO and Al2O3 as the sintering additives and spark plasma sintering (SPS) technique. The SPS sintering mechanism is discussed. The relationship between the content of sintering additives, sintering temperature and relative densities of the samples is analyzed. The results suggest that when the sintering temperature is 1300-1500°C, the content of sintering additives is 6wt.%-10wt.%, the relative density of sintered samples is 64%-96%. When the sintering temperature reaches 1400°C, the content of sintering additives is 10%, the samples can be fully dense sintered and the relative density can be up to 95%. The sintering mechanism is liquid phase sintering. The bending strength of the sintered samples is 50-403MPa and has a close correlation with the relative density.

Preparation and Performance of Neutron Absorbing Dysprosium Oxide Ceramic

2016 ◽  
Vol 697 ◽  
pp. 404-408
Author(s):  
Yu Bai Zhang ◽  
Yu Jun Zhang ◽  
Jia Xing Zhao
Keyword(s):  
Fracture Toughness ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Pressureless Sintering ◽  
Oxide Ceramic ◽  
Absorption Property ◽  
Neutron Absorption ◽  
Dysprosium Oxide ◽  
And Performance ◽  
Increasing Temperature

Dysprosium is a kind of potential neutron absorption material with the thermal neutron absorption cross area of 950 Barn. In this paper, dysprosium oxide (Dy2O3) ceramic was prepared by pressureless sintering. The density, bending strength, fracture toughness and hardness of Dy2O3 ceramics under different sintering schedule were analyzed. The density of Dy2O3 ceramics was enhanced accompanied with the increase in sintering temperature, and it was close to the theoretical value when heated at 1630 °C. Bending strength reached a maximum of 117 MPa when sintering temperature was 1570 °C. However, fracture toughness was inversely proportional to the hardness approximately. As a consequence, the optimum sintering temperature for mechanical property of Dy2O3 ceramics was 1570 °C. The morphology of fracture surface was examined by SEM. The results showed that the porosity of Dy2O3 ceramics decreased with increasing temperature. Meanwhile, the Monte-Carlo software was used to simulate the neutron absorption property. The absorbtivity was about 99.13% when the neutron source was uniform energy spectrum of 10-11 Mev~10-5 Mev and the thickness of Dy2O3 was of 20 mm.

The Influence of Sintering Temperature on Properties and Microstructure of TiN/Si3N4 Composite

2012 ◽  
Vol 512-515 ◽  
pp. 878-882
Author(s):  
Lan Er Wu ◽  
Yong Jiang
Keyword(s):  
Fracture Toughness ◽  
Vickers Hardness ◽  
Bending Strength ◽  
Fine Particles ◽  
Electrical Discharge Machining ◽  
Sintering Temperature ◽  
Sintered Sample ◽  
Β Phase ◽  
Fine Grain ◽  
The Difference

Electrical discharge machining can be used easily for the materials which has good conductivity. In order to improve conductivity of Si3N4 based ceramics, TiN/Si3N4 composite was sintered by adding TiN into Si3N4 powder. In the present research, influence of sintering temperature (1535-1925°C, 8 temperatures) on properties and microstructure of the TiN/Si3N4 composite were investigated with La2O3, AlN as sintering additives, liquid phase pressure less sintering used. Densities of the sintered sample were measured. Bending strength, hardness, fracture toughness and electrical resistively of the sample were tested. Phase composition and microstructure of the samples were analyzed by XRD, SEM and EDX. The results showed that the density and fracture toughness of the sintered bodies reached maximum at temperature of 1760°C (relative density of 97.9%; fracture toughness of 8.5 MPa•m1/2) in the sintering temperature range of 1535~1925°C. With increasing of temperature, the bending strength and hardness of the samples kept raising, reached maximum at temperature of 1925°C (bending strength of 634MPa and Vickers hardness of 1869). But the weight lost at the highest temperature was the severe. Microstructure and EDX showed that crystals of the Si3N4 transferred into complete β phase from α + β both phases. The grain of Si3N4 grew up into long columnar from equiaxial fine particles. The fine grain of TiN grew up also. The comprehensive performances of the samples are better at sintering temperature of 1760°C. The long columnar β-Si3N4 grains interweaved with conductive TiN particles, formed conductive nets through sintering. At this sintering temperature, the bending strength of TiN/Si3N4 sintered body was 560MPa，Vickers hardness 1708MPa. The conductivity of the sintered bodies was irregular with the difference of temperature. The minimum of the conductivity is 20Ω.

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