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 Graphene platelets enhanced pressureless- sintered B 4 C ceramics

2018 ◽  
Vol 5 (4) ◽  
pp. 171837 ◽  
Author(s):  
Dezhi Gao ◽  
Jie Jing ◽  
Jincheng Yu ◽  
Xue Guo ◽  
Yubai Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Electrical Resistivity ◽  
Optimal Condition ◽  
Bending Strength ◽  
Extreme Values ◽  
Overall Performance ◽  
Graphene Platelets

B 4 C ceramics with different contents of graphene platelets (GPL) were synthesized by a pressureless process in Ar atmosphere. The influences of GPL on mechanical properties, thermal conductivity and electrical resistivity of the B 4 C ceramics were investigated. Mechanical properties ran up to optimal condition with hardness of 29.1 GPa, bending strength of 383.9 GPa and fracture toughness of 5.72 MPa m 1/2 with 0.8 wt% GPL separately. Thermal conductivity and electrical resistivity reached extreme values of 26.35 W m −1  k −1 and 0.1 Ω cm −1 . Performances of the ceramics were mainly affected by the generation of non-functional-GPL and the result indicated that a large amount of non-functional-GPL could contribute to poorer overall performance. Meanwhile, two particular pullout mechanisms concerning toughness enhancing was discussed in detail.

In Situ Preparation and Mechanical Properties of (ZrB2+ZrC)/Zr3[Al(Si)]4C6 Composites

2014 ◽  
Vol 602-603 ◽  
pp. 438-442
Author(s):  
Lei Yu ◽  
Jian Yang ◽  
Tai Qiu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Bending Strength ◽  
Coefficient Of Thermal Expansion ◽  
Raw Materials ◽  
Linear Increase ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Uniform Microstructure

Fully dense (ZrB2+ZrC)/Zr3[Al (Si)]4C6 composites with ZrB2 content varying from 0 to 15 vol.% and fixed ZrC content of 10 vol.% were successfully prepared by in situ hot-pressing in Ar atmosphere using ZrH2, Al, Si, C and B4C as raw materials. With the increase of ZrB2 content, both the bending strength and fracture toughness of the composites increase and then decrease. The synergistic action of ZrB2 and ZrC as reinforcements shows significant strengthening and toughing effect to the Zr3[Al (Si)]4C6 matrix. The composite with 10 vol.% ZrB2 shows the optimal mechanical properties: 516 MPa for bending strength and 6.52 MPa·m1/2 for fracture toughness. With the increase of ZrB2 content, the Vickers hardness of the composites shows a near-linear increase from 15.3 GPa to 16.7 GPa. The strengthening and toughening effect can be ascribed to the unique mechanical properties of ZrB2 and ZrC reinforcements, the differences in coefficient of thermal expansion and modulus between them and Zr3[Al (Si)]4C6 matrix, fine grain strengthening and uniform microstructure derived by the in situ synthesis reaction.

Effects of TiN Content on Mechanical Properties and Microstructure of ATN Materials

2013 ◽  
Vol 589-590 ◽  
pp. 590-593 ◽  
Author(s):  
Min Wang ◽  
Jun Zhao
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Fracture Toughness ◽  
Vickers Hardness ◽  
Bending Strength ◽  
Sintering Temperature ◽  
Ceramic Materials ◽  
Hot Press ◽  
Hot Press Sintering ◽  
Tin Content

In order to investigate the effects of TiN content on Al2O3/TiN ceramic material (ATN), the ATN ceramic materials were prepared of TiN content in 30%, 40%, 50%, 60% in the condition of hot press sintering. The sintering temperature is 1700°C, the sintering press is 32MPa, and the holding time are 5min, 10min, 15min. The effects of TiN content on mechanical properties and microstructure of ATN ceramic materials were investigated by analyzing the bending strength, hardness, fracture toughness. The results show that ATN50 has the best mechanical property, its bending strength is 659.41MPa, vickers hardness is 13.79GPa, fracture toughness is 7.06MPa·m1/2. It is indicated that the TiN content has important effect on microstructure and mechanical properties of ATN ceramic materials.

Preparation and Properties of SiC/Phenolic Resin for the Heat of LED

2016 ◽  
Vol 848 ◽  
pp. 454-459
Author(s):  
Cong Wu ◽  
Kang Zhao ◽  
Yu Fei Tang ◽  
Ji Yuan Ma
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Powder Metallurgy ◽  
Phenolic Resin ◽  
Bending Strength ◽  
Experimental Results ◽  
Low Thermal Conductivity ◽  
Industry Standard ◽  
Insulation Performance

In order to solve the problem that low thermal conductivity of the plastics for the heat of LED, SiC/Phenolic resin for the heat of LED were fabricated combining powder metallurgy. The effects of particles diameters, content and adding nanoparticles on thermal conductivity of the fabricated composites were investigated, the mechanical properties were also characterized. The experimental results showed that the materials were obtained, and the insulation performance of the fabricated SiC/Phenolic resin was higher than the industry standard one, the thermal conductivity reached 4.1W/(m·k)-1. And the bending strength of the fabricated composites was up to 68.11MPa. The problem of low thermal conductivity of the material is expected to be solved. In addition, it is meaningful for improving LED life.

Influence of additive composition on thermal and mechanical properties of β–Si3N4 ceramics

2004 ◽  
Vol 19 (11) ◽  
pp. 3270-3278 ◽  
Author(s):  
Xinwen Zhu ◽  
Hiroyuki Hayashi ◽  
You Zhou ◽  
Kiyoshi Hirao
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Nitrogen Pressure ◽  
High Fracture Toughness ◽  
Oxygen Impurity ◽  
Thermal And Mechanical Properties ◽  
High Fracture ◽  
Doped Materials ◽  
Gas Pressure Sintering

Dense β–Si3N4 ceramics were fabricated from α–Si3N4 raw powder by gas-pressure sintering at 1900 °C for 12 h under a nitrogen pressure of 1 MPa, using four different kinds of additive compositions: Yb2O3–MgO, Yb2O3–MgSiN2, Y2O3–MgO, and Y2O3–MgSiN2. The effects of additive composition on the microstructure and thermal and mechanical properties of β–Si3N4 ceramics were investigated. It was found that the replacement of Yb2O3 by Y2O3 has no significant effect on the thermal conductivity and fracture toughness, but the replacement of MgO by MgSiN2 leads to an increase in thermal conductivity from 97 to 113 Wm-1K-1and fracture toughness from 8 to 10 MPa m1/2, respectively. The enhanced thermal conductivity of the MgSiN2-doped materials is attributed to the purification of β–Si3N4 grain and increase of Si3N4–Si3N4 contiguity, resulting from the enhanced growth of large elongated grains. The improved fracture toughness of the MgSiN2-doped materials is attributed to the increase of grain size and fraction of large elongated grains. However, the same thermal conductivity between the Yb2O3- and Y2O3-doped materials is related to not only their similar microstructures, but also the similar abilities of removing oxygen impurity in Si3N4 lattice between Yb2O3 and Y2O3. The same fracture toughness between the Yb2O3- and Y2O3-doped materials is consistent with their similar microstructures. This work implies that MgSiN2 is an effective sintering aid for developing not only high thermal conductivity (>110 Wm−1K−1) but also high fracture toughness (>10 MPa m1/2) of Si3N4 ceramics.

Fabrication of Carbon Nanotube Reinforced Boron Carbide Composite by Hot-Pressing Following Extrusion Molding

2014 ◽  
Vol 616 ◽  
pp. 27-31 ◽  
Author(s):  
Tomohiro Kobayashi ◽  
Katsumi Yoshida ◽  
Toyohiko Yano
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Elastic Modulus ◽  
Carbon Nanotube ◽  
Boron Carbide ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Bending Strength ◽  
Extrusion Direction ◽  
Sem Observation

The CNT/B4C composite with Al2O3 additive was fabricated by hot-pressing following extrusion molding of a CNT/B4C paste, and mechanical properties of the obtained composite were investigated. Many CNTs in the composite aligned along the extrusion direction from SEM observation. 3-points bending strength of the composite was slightly lower than that of the monolithic B4C. Elastic modulus and Vickers hardness of the composite drastically decreased with CNT addition. Fracture toughness of the composite was higher than that of the monolithic B4C.

scholarly journals Mechanical properties of microwave sintered Si3N4-based ceramics

2002 ◽  
Vol 34 (3) ◽  
pp. 223-229 ◽  
Author(s):  
O.I. Getman ◽  
V.V. Holoptsev ◽  
V.V. Panichkina ◽  
I.V. Plotnikov ◽  
V.K. Soolshenko
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Bending Strength ◽  
Normal Pressure ◽  
Ceramic Materials ◽  
Particle Sizes ◽  
Phase Measurements ◽  
Ceramic Samples ◽  
Mean Size ◽  
The Mean

The mechanical properties and microstructure formation processes in Si3N4+3% AI2O3+5% Y2O3(Yb2O3) ceramic compacts sintered under microwave heating (MWH) and under traditional heating (TH) were investigated. The initial ceramic materials were powder blends of silicon nitride with oxides. The mean powder particle sizes were 0.5-1.0 mim. The content of alfa-phase in the Si3N4 powder was more than 95 %. The samples were sintered at 1800BC in nitrogen at normal pressure, the heating rate in all experiments was 60BC/min. The Vickers hardness (HV), fracture toughness (K1C) and bending strength (on) were determined. The microstructures of fracture surfaces of samples were studied by SEM. Quantitative microstructure analysis was carried out. It was shown that the values of HV and Kic of ceramic samples sintered under MWH at 1800BC rose steadily with the sintering time. This caused an increase in density, which reached maximum as fast as after 30 min of the MWH sintering; the mass loss at that time amounted to 3-4 %. The porosity of sintered samples with an addition of yttria was less than 1 %, that of ytterbia was greater, 2.4 %. For similar values of relative density, the hardness and fracture toughness of ceramic samples produced under MWH were higher as compared with those of samples sintered under TH. The microstructure of samples had the form of elongated grains in a matrix of polyhedral grains of the beta-Si3N4 phase. Measurements showed the mean size of grains in samples produced by MWH to be greater that in samples produced by TH. A larger number of elongated grains were formed. It was concluded that for sintering under MWH of Si3N4-based ceramics the growth of elongated beta-Si3N4 grains and formation of a "reinforced" microstructure were promoted and thereby improved the mechanical properties of such ceramics.

Thermal Conductivity of Si₃N₄ Ceramics Fabricated From Carbothermal-reduction-derived Powder

2021 ◽  
Author(s):  
Yuelong Wang ◽  
Xingyu Li ◽  
Haoyang Wu ◽  
Baorui Jia ◽  
Deyin Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Grain Size ◽  
Flexural Strength ◽  
Grain Boundaries ◽  
Carbothermal Reduction ◽  
Secondary Phase ◽  
Gas Pressure ◽  
Gas Pressure Sintering

Abstract Si3N4-based ceramic (Si3N4-5wt%Y2O3-3wt%MgO) was obtained from carbothermal-reduction-derived powder combined with gas pressure sintering. The phase, microstructure, thermal conductivity and mechanical properties of Si3N4 ceramics were comprehensively analyzed. Dense Si3N4 ceramic with uniform grain size was obtained after sintering at 1900°C for 7 h under a N2 pressure of 1.2 MPa. The secondary phase consisted of Y4Si2O7N2 and Y2Si3O3N4 was found to gather around triangular grain boundaries. The thermal conductivity, flexural strength, hardness and fracture toughness of the Si3N4 ceramics were 95.7 W·m-1·k-1, 715 MPa, 17.2 GPa and 7.2 MPa·m1/2, respectively. The results were compared with product derived from commercial powder, the improvement of thermal conductivity (~8.3%) and fracture toughness (~4.3%) demonstrating the superiority of Si3N4 ceramics prepared from carbothermal-reduction-derived powder.

scholarly journals Silicon Nitride-Based Composites with the Addition of CNTs—A Review of Recent Progress, Challenges, and Future Prospects

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2799
Author(s):  
Awais Qadir ◽  
Péter Pinke ◽  
Ján Dusza
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Carbon Nanotube ◽  
Silicon Nitride ◽  
Wear Rate ◽  
Recent Progress ◽  
Bending Strength ◽  
Microstructure Development ◽  
Future Prospects ◽  
Microstructure Characteristics

In this overview, the results published to date concerning the development, processing, microstructure characteristics, and properties of silicon nitride/carbon nanotube (Si3N4 + CNTs) composites are summarized. The influence of the different processing routes on the microstructure development of the Si3N4 + CNTs is discussed. The effects of the CNTs addition on the mechanical properties—hardness, bending strength and fracture toughness—and tribological characteristics—wear rate and coefficient of friction—are summarized. The characteristic defects, fracture origins, toughening and damage mechanisms occurring during the testing are described. The influence of the CNTs’ addition on the thermal and functional properties of the composites is discussed as well. New trends in the development of these composites with significant potential for future applications are outlined.

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.

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