Processing and Mechanical Properties of SiC-Metal Interpenetrating Composites

1995 ◽  
Vol 410 ◽  
Author(s):  
Leszek Hozer ◽  
Yet-Ming Chiang ◽  
Svetlana Ivanova ◽  
Isa Bar-On
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
Fracture Strength ◽  
Exchange Process ◽  
Secondary Phase ◽  
Single Edge ◽  
Ductile Metal ◽  
Silicon Carbides ◽  
Beam Technique

ABSTRACTIn this paper we demonstrate a liquid exchange process to introduce a ductile metal reinforcement phase in the amount of 10–30 vol. % into reaction-bonded silicon carbides (RBSCs). Immersion of RBSC in pure Al or Al-Si melts enables diffusional replacement of secondary phase silicon with metal. The Al and Al-Si exchanged composites show improvement in fracture toughness (single edge precracked beam technique) to 6–7 MPa·m1/2 as compared to 3–4 MPa·m1/2 in otherwise similar siliconized silicon carbide. Increased fracture strength (four point flexure) was also observed after the liquid exchange process.

Liquid-exchange processing and properties of SiC–Al composites

1997 ◽  
Vol 12 (7) ◽  
pp. 1785-1789 ◽  
Author(s):  
Leszek Hozer ◽  
Yet-Ming Chiang ◽  
Svetlana Ivanova ◽  
Isa Bar-On
Keyword(s):  
Thermal Conductivity ◽  
Fracture Toughness ◽  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Exchange Process ◽  
Secondary Phase ◽  
Single Edge ◽  
Silicon Phase ◽  
Silicon Carbides ◽  
Beam Technique

In this paper we demonstrate a novel liquid-exchange process to replace a secondary silicon phase in reaction-bonded siliconized silicon carbides (RBSC's) with a ductile metal reinforcement phase. When RBSC is exchanged with pure Al or Al–Si liquid, secondary phase silicon is dissolved and is substituted by Al or Al–Si alloy. The resulting composites show improvements in fracture toughness (single-edge precracked beam technique), with KIC value up to 8.6 Mpa · m1/2, compared to 3–4 MPa · m1/2 in otherwise similar siliconized silicon carbide. Increased fracture strength (four point flexure) was also observed after the liquid exchange process. The processing furthermore allows the coefficient of thermal expansion to be adjusted, and the thermal conductivity increased, for electronic packaging applications.

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.

Microwave Sintering of Alumina-Silicon Carbide Nanocomposites

2007 ◽  
Vol 336-338 ◽  
pp. 1072-1075 ◽  
Author(s):  
Kaleem Ahmad ◽  
Wei Pan ◽  
Wen Jie Si
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
Microwave Sintering ◽  
Thermal Runaway ◽  
Surface Heating ◽  
Densification Behavior

Densification behavior, microstructural developments and mechanical properties of 5 wt% SiC nano particulate toughened Al2O3 composites were prepared by using microwave sintering at different sintering temperatures. Densities of up to 97.5% of the theoretical value were achieved at temperature as low as 1380°C. Improvements in fracture toughness and bending strengths are of the order of 99% theoretical dense conventionally sintered composites. Surface heating was observed at the final stages of densification. No thermal runaway was observed in the nanocomposites due to presence of SiC spheroids.

Microstructure Development and Mechanical Properties of Ce-TZP/La- β-Alumina Composites

1992 ◽  
Vol 274 ◽  
Author(s):  
Takashi Fujii ◽  
Hironobu Muragaki ◽  
Hiraku Hatano ◽  
Shin-Ichi Hirano
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Hydrothermal Treatment ◽  
Fracture Strength ◽  
Sintered Body ◽  
Microstructure Development ◽  
Lanthanum Aluminate ◽  
Alumina Composites ◽  
In Situ Formation

ABSTRACTSimultaneous additions of lanthanum aluminate(LAL) and Al2O3 to Ce-TZP (12mol% CeO2-ZrO2) lead to the in-situ formation of lanthanum- β-alumina(LBA) platelets (∼1.0.μ m in width and 5 ∼10 μ m in length) in the Ce-TZP matrix during sintering. The composites showed a fracture toughness(SEPB method) of 9.5 MPa · m0.5 and fracture strength of 960 MPa. which are remarkably improved from Ce-TZP sintered body (8.5 MPa · m0.5 and 560 MPa).The composites also exhibit the no degradation by hydrothermal treatment.

On the Role of Grain-Boundary Films in Optimizing the Mechanical Properties of Silicon Carbide Ceramics

2004 ◽  
Vol 818 ◽  
Author(s):  
R. O. Ritchie ◽  
X.-F. Zhang ◽  
L. C. De Jonghe
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
Grain Boundary ◽  
Elevated Temperatures ◽  
Boundary Structure ◽  
Intergranular Films ◽  
Grain Boundary Structure ◽  
Silicon Carbide Ceramics

AbstractThrough control of the grain-boundary structure, principally in the nature of the nanoscale intergranular films, a silicon carbide with a fracture toughness as high as 9.1 MPa.m1/2 has been developed by hot pressing β-SiC powder with aluminum, boron, and carbon additions (ABC-SiC). Central in this material development has been systematic transmission electron microscopy (TEM) and mechanical characterizations. In particular, atomic-resolution electron microscopy and nanoprobe composition quantification were combined in analyzing grain boundary structure and nanoscale structural features. Elongated SiC grains with 1 nm-wide amorphous intergranular films were believed to be responsible for the in situ toughening of this material, specifically by mechanisms of crack deflection and grain bridging. Two methods were found to be effective in modifying microstructure and optimizing mechanical performance. First, prescribed post-annealing treatments at temperatures between 1100 and 1500°C were seen to cause full crystallization of the amorphous intergranular films and to introduce uniformly dispersed nanoprecipitates within SiC matrix grains; in addition, lattice diffusion of aluminum at elevated temperatures was seen to alter grain-boundary composition. Second, adjusting the nominal content of sintering additives was also observed to change the grain morphology, the grain-boundary structure, and the phase composition of the ABC-SiC. In this regard, the roles of individual additives in developing boundary microstructures were identified; this was demonstrated to be critical in optimizing the mechanical properties, including fracture toughness and fatigue resistance at ambient and elevated temperatures, flexural strength, wear resistance, and creep resistance.

Mechanical Properties of Diamond Fibres

1995 ◽  
Vol 383 ◽  
Author(s):  
N. M. Everitt ◽  
R. A. Shatwell ◽  
E. Kalaugher ◽  
E. Nicholson
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Grain Size ◽  
Fracture Strength ◽  
Coating Thickness ◽  
Tensile Testing ◽  
Volume Fraction ◽  
Thick Films ◽  
Diamond Coating ◽  
Bending Tests

ABSTRACTTungsten and silicon carbide fibres have been coated with diamond using the HFCVD technique. The diamond volume fraction varied between 26% and 73%. Resonance in bending tests gave a Young's modulus of 880 GPa for the diamond coating. Tensile testing indicated that the diamond fracture strength was between 600 MPa and 2000 MPa, depending on the coating thickness, and thus the grain size, of the diamond. The strain to failure of the diamond coating in bending was approximately 0.15% for 25 μm thick films.

Correlation between microstructure and mechanical properties in silicon carbide with alumina addition

1993 ◽  
Vol 8 (7) ◽  
pp. 1635-1643 ◽  
Author(s):  
S.S. Shinozaki ◽  
J. Hangas ◽  
K.R. Carduner ◽  
M.J. Rokosz ◽  
K. Suzuki ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
Analytical Electron Microscopy ◽  
High Strength ◽  
High Fracture Toughness ◽  
Sintered Body ◽  
High Fracture ◽  
High Fatigue ◽  
Alumina Addition

The microstructure of pressureless sintered silicon carbide (SiC) materials with alumina (Al2O3) addition was investigated using analytical electron microscopy and nuclear magnetic resonance. A sintered body with a density of higher than 99% theoretical was obtained with an addition of 5 wt.% Al2O3. The sintered body (SiC–Al2O3) has high strength, high fracture toughness, and high fatigue resistance. Its fracture toughness is approximately 5 MPa-m1/2, which is twice as high as that of pressureless sintered SiC materials with boron and carbon additions (SiC–B–C). The correlation between the microstructure and the mechanical properties is presented here. The starting β–SiC powder is mostly transformed to α–SiC with various polytype distributions during the sintering process. The microstructure has homogeneously distributed, fine, plate-like interlocking gains with a high aspect ratio. Well-developed basal planes form parallel and elongated boundaries, and the crystal structure is mostly the 6H polytype (56%) mixed with thin lamellar 4H.

High Strength and Toughness Al2O3 Composite Materials for the Improvement of Ceramic Channel in SRL Hot Dipping System

2010 ◽  
Vol 658 ◽  
pp. 416-419 ◽  
Author(s):  
Hyun Hwi Lee ◽  
Seung Ho Kim ◽  
Bhupendra Joshi ◽  
Sung Hun Cho ◽  
Soo Wohn Lee
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Composite Materials ◽  
Flexural Strength ◽  
Fracture Strength ◽  
Hot Pressing ◽  
High Strength ◽  
Economic Feasibility ◽  
Different Content ◽  
Strength And Toughness

The ceramic channel is very important in SRL hot dipping system. High strength and fracture toughness of ceramic channel materials can improve the quality, productivity and economic feasibility of zinc plated steel. The purpose of this research was to find out the most suitable conditions of the ceramic channel that have best fracture strength and fracture toughness. The hot pressed composite materials was carried out by hot pressing Al2O3 with different content of ZrO2. The composite contained from 0-20 wt.% ZrO2. Hot pressed composite materials were observed for mechanical properties (density, hardness, fracture toughness and flexural strength) and microstructure.

Mechanical Properties of Transparent Polycrystalline Silicon Nitride

2006 ◽  
Vol 317-318 ◽  
pp. 305-308 ◽  
Author(s):  
Rak Joo Sung ◽  
Takafumi Kusunose ◽  
Tadachika Nakayama ◽  
Yoon Ho Kim ◽  
Tohru Sekino ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Nitride ◽  
Young’S Modulus ◽  
Fracture Strength ◽  
Polycrystalline Silicon ◽  
Volume Fraction ◽  
Young's Modulus ◽  
Β Phase ◽  
Α Phase

A novel transparent polycrystalline silicon nitride was fabricated by hot-press sintering with MgO and AlN as additives. The mixed powder with 3 wt.% MgO and 9 wt.% AlN was sintered at 1900oC for 1 hour under 30 MPa pressure in a nitrogen gas atmosphere. Transparent polycrystalline silicon nitride was successfully fabricated. The mechanical properties such as density, hardness, young’s modulus, fracture strength and fracture toughness were evaluated. The effect of α/β phase on the mechanical properties of transparent polycrystalline silicon nitride was investigated. The properties were changed depending on the amount of α/β phase. The hardness and Young's modulus increased with increasing the volume fraction of α-phase fraction as a reflection of the higher hardness of α-phase Si3N4. The fracture toughness and fracture strength decreased with decreasing the volume fraction of β-phase Si3N4.

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