Preparation and Property Study of 3D Cf/Si-Ti-C-O Composites Fabricated with Polytitanocarbosilane by PIP Process

2007 ◽  
Vol 336-338 ◽  
pp. 1242-1244
Author(s):  
Qi Kun Wang ◽  
Hai Feng Hu ◽  
Wen Wei Zheng ◽  
Qing Song Ma ◽  
Zhao Hui Chen
Keyword(s):  
Fracture Toughness ◽  
Flexural Strength ◽  
Thermal Shock ◽  
Brittle Failure ◽  
Room Temperature ◽  
Oxidation Treatment ◽  
Fracture Failure ◽  
The Matrix ◽  
Polymer Infiltration ◽  
Strength Retention

In this paper, 3D Cf/Si-Ti-C-O composites were prepared with a polytitanocarbosilane (PTC) via polymer infiltration and pyrolysis (PIP) process, and accordingly the mechanical, oxidation resisting and thermal shock resisting properties were investigated. The composites with density of 1.93g·cm-3 show rather high flexural strength (485.3MPa) and fracture toughness (19.95MPa⋅m1/2), and typical non-brittle fracture failure mode. After oxidation treatment at 1300°C for 10 minutes in air, the flexural strength of the samples is 306.2MPa, with 63% strength retention. After 5 times of thermal shock tests from room temperature to 1300°C, the flexural strength of the samples is 408.9MPa, about 85% strength retention. SEM observation also testifies non-brittle failure because many fibers are pulled out on the fracture surface. After oxidation treatment, the matrix shows no changes from XRD measurement.

Microstructure and Mechanical Properties of SiC Whisker-Reinforced ZrB2 Ultra-High Temperature Ceramic

2008 ◽  
Vol 368-372 ◽  
pp. 1730-1732 ◽  
Author(s):  
Ping Hu ◽  
Xing Hong Zhang ◽  
Jie Cai Han ◽  
Song He Meng ◽  
Bao Lin Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Temperature ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Room Temperature ◽  
Pressing Temperature ◽  
Sintering Time ◽  
Microstructure And Mechanical Properties ◽  
Ultra High Temperature

SiC whisker-reinforced ZrB2 matrix ultra-high temperature ceramic were prepared at 2000°C for 1 h under 30MPa by hot pressing and the effects of whisker on flexural strength and fracture toughness of the composites was examined. The flexural strength and fracture toughness are 510±25MPa and 4.05±0.20MPa⋅m1/2 at room temperature, respectively. Comparing with the SiC particles-reinforced ZrB2 ceramic, no significant increase in both strength and toughness was observed. The microstructure of the composite showed that the SiC whisker was destroyed because the SiC whisker degraded due to rapid atom diffusivity at high temperature. The results suggested that some related parameters such as the lower hot-pressing temperature, a short sintering time should be controlled in order to obtain SiC whiskerreinforced ZrB2 composite with high properties.

Effect of AlF3 Content on Microstructure and Properties of Mullite/Al2O3 Composite Ceramics

2018 ◽  
Vol 922 ◽  
pp. 62-67
Author(s):  
Ke Zheng Sang ◽  
Fan Wang ◽  
De Jun Zeng ◽  
Hong Wei Li
Keyword(s):  
Fracture Toughness ◽  
Flexural Strength ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Diameter Ratio ◽  
Pressureless Sintering ◽  
Composite Ceramics ◽  
Microstructure And Properties ◽  
Shock Resistance ◽  
Mullite Whiskers

To reinforce the mullite/Al2O3 composite ceramics through formation of mullite whiskers, the composite ceramics were prepared by pressureless sintering using different AlF3 content. The microstructure, porosity, fracture toughness and thermal shock resistance of the composite ceramics were investigated. The results show that the addition of AlF3 can promote the mullite whisker formations, and the whiskers with the size of 3～10μm in diameter and a length-diameter ratio of 10～15 are obtained by sintering at 1600°C with the AlF3 content of 5wt%. Fracture toughness and thermal shock resistance of the composite ceramics are improved by the formation of mullite whisker. The fracture toughness of 4.79MPa•m1/2 can be obtained, and the 95.18% flexural strength remained after thermal shock.

The Room Temperature and Elevated Temperature Fracture Toughness Response of Alloy A-286

1978 ◽  
Vol 100 (2) ◽  
pp. 195-199 ◽  
Author(s):  
W. J. Mills
Keyword(s):  
Fracture Toughness ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Second Phase ◽  
Surface Micromorphology ◽  
Second Phase Particles ◽  
The Matrix ◽  
Temperature Fracture ◽  
Increasing Temperature ◽  
Base Superalloy

The elastic-plastic fracture toughness (JIc) response of precipitation strengthened Alloy A-286 has been evaluated by the multi-specimen R-curve technique at room temperature, 700 K (800°F) and 811 K (1000°F). The fracture toughness of this iron-base superalloy was found to decrease with increasing temperature. This phenomenon was attributed to a reduction in the materials’s strength and ductility at elevated temperatures. Electron fractographic examination revealed that the overall fracture surface micromorphology, a duplex dimple structure coupled with stringer troughs, was independent of test temperature. In addition, the fracture resistance of Alloy A-286 was found to be weakened by the presence of a nonuniform distribution of second phase particles throughout the matrix.

Mechanical and Thermal Properties of SiC-SiC Composites Made With CVR SiC Fibers

1995 ◽  
Vol 410 ◽  
Author(s):  
W. Kowbel ◽  
H. T. Tsou ◽  
C. A. Bruce ◽  
J. C. Withers
Keyword(s):  
Low Cost ◽  
Chemical Vapor ◽  
Dimensional Change ◽  
Mechanical And Thermal Properties ◽  
The Matrix ◽  
Sic Composites ◽  
Sic Reinforcement ◽  
Polymer Infiltration ◽  
Strength Retention ◽  
Graphite Fabric

ABSTRACTNicalon fiber is the primary reinforcement in SiC-SiC composites currently produced by a variety of techniques including CVI and polymer infiltration. Low strength retention and dimensional change at high temperatures of the Nicalon fibers limits the choice of manufacturing processes which can be employed to produce low cost SiC-SiC composites. MER has developed a SiC reinforcement based upon the conversion of low cost carbon fabric to SiC via a Chemical Vapor Reaction (CVR) process. These new SiC filaments exhibit excellent creep resistance at temperatures up to 1600°C. SiC-SiC composites were fabricated using different types of graphite fabric converted to SiC fabric utilizing the CVR process combined with a polycarbosilane (PCS) infiltration and CVI densification. In addition, enhancement of the composite through-the-thickness thermal conductivity was accomplished via boron doping of the matrix. A correlation between processing conditions, microstructure and properties of the SiC-SiC composites will be presented.

The Temperature Dependence of Yield Stress and Fracture Toughness in Unstabilized Zirconia Crystals

1986 ◽  
Vol 78 ◽  
Author(s):  
T. W. Coyle ◽  
R. P. Ingel ◽  
P. A. Willging
Keyword(s):  
Fracture Toughness ◽  
Flexural Strength ◽  
Temperature Dependence ◽  
Yield Stress ◽  
Test Temperature ◽  
Room Temperature ◽  
Single Edge ◽  
Melting Technique ◽  
Strength Tests ◽  
Edge Notch

ABSTRACTThe flexural strength and the single edge notch beam fracture toughness of undoped ZrO2 crystals, grown by the skull melting technique, were examined from room temperature to 1400°C. On heating the toughness increased with test temperature to a maximum of 4.0 MPajm at 1225°C then gradually decreased to 2.6 MPa/m. Upon cooling after a 20 minute hold at 1250°C an increase in toughness to 5 MPa/m was observed at 1200°C; upon cooling to lower temperatures Kic gradually diminished. The loaddeflection curves for the flexural strength tests showed marked nonlinearity before failure for samples tested on cooling. The temperature dependence of the apparent yield stress suggests that initial yielding occurs by slip above 1200°C but that from 1200°C to 1050°C the observed yielding is due to stress induced tetragonal to monoclinic transformation.

Large Bulk Al2O3/ZrO2 (Y2O3) Nanocrystalline Composites Prepared by Combustion Synthesis under High Gravity

2010 ◽  
Vol 434-435 ◽  
pp. 9-12 ◽  
Author(s):  
Zhong Min Zhao ◽  
Long Zhang ◽  
Chuan Zeng Pan ◽  
Quan Yang ◽  
Zhen Sheng Qu ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Flexural Strength ◽  
Relative Density ◽  
Combustion Synthesis ◽  
High Gravity ◽  
Gravity Level ◽  
Nanocrystalline Composites ◽  
Large Bulk ◽  
The Matrix ◽  
High Gravity Field

The large bulk Al2O3/ZrO2 (Y2O3) eutectics were achieved by combustion synthesis in high-gravity field. With increasing high-gravity level, the matrix of eutectics transformed the rod-shaped colonies from the cellular ones, and the nanocrystalline microstructures came into existence as the high-gravity level was larger than 200g. The relative density, hardness, flexural strength and fracture toughness increased simultaneously with increasing high-gravity level, and reached the maximum values of 98.6%, 18.6GPa, 1248MPa and 15.6MPa•m1/2 respectively as the high-gravity level was 250g.

Effects of CeO2-Rich Mixed Rare Earth on the Mechanical Properties of Al2O3-Mullite Based Foam Ceramics

2010 ◽  
Vol 150-151 ◽  
pp. 815-820
Author(s):  
Shu Jun Ji ◽  
Xue Yi Guo ◽  
Jian Xiong Dong ◽  
Peng Su
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Rare Earth ◽  
Flexural Strength ◽  
Room Temperature ◽  
Strengthening Mechanism ◽  
Mechanism Analysis ◽  
Rare Earth Addition ◽  
The Matrix ◽  
Ceramic Microstructure

Using corundum, quartz, kaoline, etc, as base components and CeO2-rich mixed rare earth as modifier, foam ceramics were fabricated adopting the organic foam impregnation process. The mixed rare earth addition had much improving effects on the matrix mechanical properties owing to much glass phase and acerate mullite growing. While 3wt% was considered to be the optimal addition, in this case, homogeneous and compact ceramic microstructure with maximal glass condensation and minimal porosity formed, with the matrix compressive strength and the flexural strength at room temperature reached 0.87MPa and 0.66MPa respectively, which were 52.6% and 73.7% higher than the original samples respectively. As the mixed rare earth addition exceeded further, the compressive strength increased slowly and the flexural strength descended gradually. XRD and SEM were used to structure strengthening mechanism analysis.

scholarly journals Evaluasi Pembuatan Prototype Package Tray Biokomposit Serat Tebu- Polypropylene untuk Kebutuhan Interior Mobil

2020 ◽  
Vol 17 (2) ◽  
pp. 42-47
Author(s):  
Patrik Permana Putra Wijaya ◽  
Juliana Anggono
Keyword(s):  
Mechanical Property ◽  
Flexural Strength ◽  
Sugarcane Bagasse ◽  
Room Temperature ◽  
Natural Fibers ◽  
Interfacial Region ◽  
Flexural Test ◽  
The Matrix ◽  
Naoh Solution ◽  
Strong Material

Natural fibers used in the fabrication of biocomposite product can support the need of the industries for lightweight yet strong material. Sugarcane bagasse is one of the available natural fibers in Indonesia. There have been some research done on these bagasse fibers as reinforcement materials for plastics and their incorporation to the matrix has improved its strength. This research aimed to evaluate the fabrication of a car package tray prototype. The composition and the bagasse were prepared in accordance with the previous research in which the bagasse were alkali treated using NaOH solution of 8 wt% for one hour at room temperature. The hotpressed prototype was evaluated by its physical outlook and the mechanical property of its preform. The flexural test shows a low flexural strength of the prototype (7.4 MPa) compared to the required strength of the current material (woodboard) used by the industry (35.58 MPa). The evaluation shows the clustering of bagasse fibers, uneven distribution of sugarcane/PP in the structure and low adhesion at the interfacial region between bagasse fibers and PP.

Investigation of NiAl–TiB2in situcomposites

1997 ◽  
Vol 12 (4) ◽  
pp. 1083-1090 ◽  
Author(s):  
J. T. Guo ◽  
Z. P. Xing
Keyword(s):  
Fracture Toughness ◽  
Yield Strength ◽  
Hot Pressing ◽  
Room Temperature ◽  
Tensile Yield Strength ◽  
Matrix Composites ◽  
Orientation Relationships ◽  
The Matrix ◽  
Atomically Flat ◽  
Nial Matrix

A hot-pressing aided exothermic synthesis (HPES) technique to fabricate NiAl matrix composites containing 0 and 20 vol.% TiB2 particles was developed. The conversion of mixtures of elements to the product was complete after processing, and TiB2 particles in the matrix were uniformly dispersed. The microstructure and interfaces were very thermally stable. The interfaces between NiAl and TiB2 were atomically flat, sharp, and generally free from interfacial phases. In some cases, however, thin amorphous layers existed at NiAl/TiB2 interfaces. At least three kinds of orientation relationships between TiB2 and NiAl were observed. The compressive yield strengths at room temperature and at 1000 °C of the composite were approximately three times as strong as those of the unreinforced NiAl. The tensile yield strength at 980 °C of the composite was about three times stronger than that of NiAl. The ambient fracture toughness of the composite was slightly greater than that of the monolithic NiAl.

Processing and Properties of 2D Cf/Si-O-C Composites Using Silicone Resin

2007 ◽  
Vol 336-338 ◽  
pp. 1251-1253
Author(s):  
Ke Jian ◽  
Zhao Hui Chen ◽  
Qing Song Ma ◽  
Hai Feng Hu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Carbon Fiber ◽  
Flexural Strength ◽  
Thermal Shock ◽  
Silicon Oxycarbide ◽  
Silicone Resin ◽  
Carbon Fiber Cloth ◽  
Thermal Shock Behavior ◽  
First Time

SR-249, a kind of polysiloxane (PSO), was used as the precursor for the first time to fabricate carbon fiber cloth reinforced silicon oxycarbide (2D Cf/Si-O-C) composites. The cure and pyrolysis of the SR-249 as well as the mechanical properties, oxidation and thermal shock behavior of the composites were investigated in the paper. The flexural strength and fracture toughness of the composites reached 217.6 MPa and 12.5 MPa·m1/2, respectively. After soaked at 1300°C under the static air for 10 min, the composites retained 58.5% flexural strength and 64.5% fracture toughness. The thermal shock behavior of the composites was studied by water quenched method. The composites retained 49.3% flexural strength and 47.4% fracture toughness after 10 times of quenching from 1200 to 20°C.

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