Effect of Structure on the Mechanical Properties of PAN-Based Carbon Fibers during Graphitization

2011 ◽  
Vol 686 ◽  
pp. 770-777 ◽  
Author(s):  
Hao Xiao ◽  
Yong Gen Lu ◽  
Xian Ying Qin ◽  
Ya Wen
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Fiber Surface ◽  
Total Porosity ◽  
Interlayer Spacing ◽  
Temperature Treatment ◽  
Treatment Temperature ◽  
High Temperature Treatment ◽  
X Ray Diffraction ◽  
Crystallite Sizes

An investigation was conducted to determine the influence of high temperature treatment from 1600°C to 2800°C under stretching stress of 10MPa on PAN-based carbon fiber structure and physical properties. The tensile strength of fibers decreased from 4.5GPa to 2.97GPa with increasing treatment temperature up to 2800°C，while the modulus of fibers increased from 230GPa to 375GPa The texture in the longitudinal surface of fibers through heat treatment was characterized using a scanning electron microscopy. The contours of fiber surface became accidented with gaps becoming deeper as temperature increased. It has been observed that both the crystallite sizes (La, Lc) and the degree of preferred orientation increasd, while the crystallite interlayer spacing (d002) decreased by X-ray diffraction analysis with increasing heat-treatment temperature. The total porosity of fibers decreased from 21.01% to 15.09% and while the density of fibers increased from 1.720g/cm-3to1.886 g/cm-3with increasing heat-treatment. In addition, the relationship between mechanical properties and structure of variants was also explored in detail.

Precipitate Phases and Mechanical Properties of Heat-Treated ASTM F 90 Co-Cr-W-Ni Alloy

2014 ◽  
Vol 616 ◽  
pp. 258-262 ◽  
Author(s):  
Kosuke Ueki ◽  
Kyosuke Ueda ◽  
Takayuki Narushima
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Biomedical Applications ◽  
Treatment Temperature ◽  
X Ray Diffraction ◽  
Precipitation Behavior ◽  
X Ray ◽  
Phase Precipitate ◽  
Heat Treated ◽  
Ni Alloy

The precipitation behavior during heat treatment and resulting mechanical properties of ASTM F 90 Co-20Cr-15W-10Ni (mass%) alloys were investigated with regards to their biomedical applications. Heat treatment was conducted at temperatures of 873 to 1623 K, for a holding time of 259.2 ks. The precipitates produced were then electrolytically extracted from the alloys and analyzed by X-ray diffraction (XRD). This revealed that the precipitates formed were an M23X6 type and/or η-phase (i.e., an M6X-M12X type). The M23X6-type precipitate was detected across the entire heat-treatment temperature range; however, the η-phase precipitate was only detected at 1073 to 1473 K, becoming dominant at 1173 to 1373 K. The formation of M23X6 type precipitates at 873 K is shown to improve the mechanical properties of this alloy, whereas the domination by the η-phase precipitate at higher temperatures causes deterioration in the ductility.

Experimental Investigation of the Effects of High Temperature Treatment on Quasi-Static Mechanical Characteristics of EMWM Materials

2021 ◽  
Author(s):  
Yanhong Ma ◽  
Tianyu Liang ◽  
Jie Hong
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Loss Factor ◽  
Mechanical Characteristics ◽  
Temperature Treatment ◽  
Treatment Temperature ◽  
Tangent Modulus ◽  
High Temperature Treatment ◽  
Treatment Processes ◽  
Static Mechanical

Abstract This paper investigates the influence of high temperature treatment processes on the mechanical characteristics of entangled metallic wire materials (EMWM) via quasi-static compression tests. The treatment methods including high-temperature treatment and high-temperature with loading treatment were tested. The variation effects of size in molding direction, tangent modulus and loss factor were obtained by contrast results of EMWM specimens via the treatment processes with initial performance. The results indicate that the treatment processes proposed in this study can significantly improve the mechanical properties of EMWM materials and have a wide range of application for EMWM specimens with different structural parameters. After the treatment processes, the size of specimens in molding direction decreased slightly, the tangent modulus increased significantly, and the loss factor decreased slightly. With the increase of treatment temperature, the variation of mechanical parameters intensified. For EMWM specimens with different relative densities and heights, the treatment processes still have a significant improvement effect on quasi-static mechanical properties. Finally, the secondary molding theory is carried out to explain the influence of high temperature treatment process on EMWM’s dimensions and mechanical properties. The effects of treatment temperature and repetition times obtained in this study are relevant to the design of treatment processes for EMWM materials.

Mechanical Properties and Microstructure of Li2O-SiO2-P2O5-Al2O3-K2O-CaO Glass-Ceramics

2018 ◽  
Vol 766 ◽  
pp. 164-169
Author(s):  
Manlika Kamnoy ◽  
Uraiwan Intatha ◽  
Anocha Munpakdee ◽  
Sukum Eitssayeam ◽  
Tawee Tunkasiri
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Vickers Hardness ◽  
Glass Ceramics ◽  
Treatment Temperature ◽  
X Ray Diffraction ◽  
Heat Treated ◽  
Prepared Glass ◽  
Optimum Heat ◽  
Hardness Values

In this study, the mechanical properties and microstructure of lithium disilicate glass–ceramics in the Li2O-SiO2-Al2O3-K2O-P2O5-ZrO2-CaO glass system were investigated. The glass-ceramics were prepared from the glass melt by casting into mold on hotplate. After that the glass was heat treated at 650-800 °C for 2 h. The heat treatment temperatures were determined from the differential thermal analysis (DTA). The phase formation and microstructure of the glass–ceramics were characterized by X-ray diffraction (XRD) technique and the scanning electron microscopy (SEM). Moreover, the mechanical properties was investigated by Vickers hardness testing. The results indicated that the samples confirmed the occurrence of Li2SiO3, Li2Si2O5, Li3PO4, and LiAlSi2O6 phases in the prepared glass ceramics. The optimum heat treatment temperature results in the physical properties with a high Vickers hardness values in the range of 5.4-5.8 GPa.

Preparation of Polyacrylonitrile High Modulus Carbon Fibers by Catalytic Graphitization Using Boron

2011 ◽  
Vol 686 ◽  
pp. 778-783 ◽  
Author(s):  
Ya Wen ◽  
Yong Gen Lu ◽  
Xian Ying Qin ◽  
Hao Xiao
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Boric Acid ◽  
Carbon Fibers ◽  
Tensile Modulus ◽  
Interlayer Spacing ◽  
High Modulus ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalytic Graphitization

Catalytic graphitization of polyacrylonitrile-based carbon fiber by doping boric acid was reported in this paper. The microstructure and mechanical properties of polyacrylonitrile-based carbon fibers with and without doping boric acid after heat treatment of 1300°C,1500°C,1800°C, 2100°C,2300°C,2400°Cand 2500°Cwas investigated by X-ray diffraction (XRD) and mechanical testing. The results showed that the tensile modulus of the carbon fibers either boron modified or not, increased obviously with increasing temperatures, and that of the modified carbon fibers was much higher than the unmodified fibers at all temperatures, reaching 404Gpa when the fiber was graphitized at 2500°C. The tensile strength of the modified carbon fibers was lower than the unmodified ones after being graphitized at temperatures below 2300°C, but increased to 2.69 GPa and 2.46 GPa respectively after the fibers were treated at 2300°C and 2500°C, which were higher than that of unmodified fibers treated under the same conditions, indicatinging that the mechanism of boron catalytic graphitization changed at the temperatures higher than 2300°C. It also showed that the interlayer spacing (d002) decreased, while the crystallite size (Lc) and the orientation increased with increasing temperatures.

Permanent Mold Casting Practice and Microstructure and Mechanical Properties of Thin-Sectioned ADI Casting

2007 ◽  
Vol 26-28 ◽  
pp. 531-534
Author(s):  
B.M. Moon ◽  
Bong Hwan Kim ◽  
Je Sik Shin ◽  
Sang Mok Lee
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Ductile Cast Iron ◽  
Treatment Temperature ◽  
Chemical Compositions ◽  
Permanent Mold ◽  
Permanent Mold Casting ◽  
Treatment Practice ◽  
Mold Casting ◽  
Si Content

For thin-walled casting development of austempered ductile iron (ADI), permanent mold casting and accompanied heat treatment practice were systematically investigated to suppress and/or remove chill defects of ductile cast iron (DCI) with various thickness of 2 to 9 mm and to ensure mechanical properties of the final ADI casting. Si content was increased up to 3.8% to reduce the chill formation tendency under a high cooling rate. The residual Mg content remarkably affected the nodule count, while the nodule size and spherodization were proven to have weak relationships. Austenitizing process followed by austempering was very sensitive to chemical compositions (Si and Sn) and heat treatment temperature. As a practical application, the steel bar coupler for a structural frame was tried to produce without subsequent machining.

In Situ X-Ray Diffraction Studies of Crystallization Growth Behavior in ZnO-Bi2O3-B2O3 Glass as a Route to Functional Optical Devices

MRS Advances ◽  
2018 ◽  
Vol 3 (11) ◽  
pp. 563-567 ◽  
Author(s):  
Quentin Altemose ◽  
Katrina Raichle ◽  
Brittani Schnable ◽  
Casey Schwarz ◽  
Myungkoo Kang ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Glass Ceramics ◽  
Treatment Temperature ◽  
Crystal Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Xrd ◽  
Dsc Measurements ◽  
Transmission Window

ABSTRACTTransparent optical ZnO–Bi2O3–B2O3 (ZBB) glass-ceramics were created by the melt quenching technique. In this work, a melt of the glass containing stoichiometric ratios of Zn/Bi/B and As was studied. Differential scanning calorimeter (DSC) measurements was used to measure the thermal behavior. VIS/NIR transmission measurements were used to determine the transmission window. X-ray diffraction (XRD) was used to determine crystal phase. In this study, we explore new techniques and report a detailed study of in-situ XRD of the ZBB composition in order to correlate nucleation temperature, heat treatment temperature, and heat treatment duration with induced crystal phase.

scholarly journals Effect of Intercalation Structure of Organo-Modified Montmorillonite/Polylactic Acid on Wheat Straw Fiber/Polylactic Acid Composites

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 896 ◽  
Author(s):  
Qiqi Fan ◽  
Guangping Han ◽  
Wanli Cheng ◽  
Huafeng Tian ◽  
Dong Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermogravimetric Analysis ◽  
Wheat Straw ◽  
Polylactic Acid ◽  
Low Cost ◽  
Interlayer Spacing ◽  
Positive Influence ◽  
X Ray Diffraction ◽  
Ft Ir ◽  
Ir Analysis

In this work, an easy way to prepare the polylactic acid (PLA)/wheat straw fiber (WSF) composite was proposed. The method involved uses either the dopamine-treated WSF or the two-step montmorillonite (MMT)-modified WSF as the filler material. In order to achieve the dispersibility and exfoliation of MMT, it was modified by 12-aminododecanoic acid using a two-step route. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed to characterize the modified MMT and the coated WSF. As for the properties of PLA/WSF composites, some thermal (using Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis) and mechanical properties (flexural, tensile, and impact) were analyzed. The results showed that the dopamine was successfully coated onto the WSF. Furthermore, Na-MMT was successfully transformed to organo-montmorillonite (OMMT) and formed an exfoliated structure. In addition, a better dispersion of MMT was obtained using the two-step treatment. The interlayer spacing of modified MMT was 4.06 nm, which was 123% higher than that of the unmodified MMT. Additionally, FT-IR analysis suggested that OMMT diffused into the PLA matrix. The thermogravimetric analysis (TGA) showed that a higher thermal stability of PLA/WSF composites was obtained for the modified MMT and dopamine. The results also showed that both the dopamine treated WSF and the two-step-treated MMT exhibited a positive influence on the mechanical properties of PLA/WSF composites, especially on the tensile strength, which increased by 367% compared to the unmodified precursors. This route offers researchers a potential scheme to improve the thermal and mechanical properties of PLA/WSF composites in a low-cost way.

scholarly journals Comparison of Mechanical Behavior and Acoustic Emission Characteristics of Three Thermally-Damaged Rocks

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2350 ◽  
Author(s):  
Jun Peng ◽  
Sheng-Qi Yang
Keyword(s):  
Mechanical Properties ◽  
Acoustic Emission ◽  
Mechanical Behavior ◽  
Thermal Damage ◽  
Strain Curve ◽  
Treatment Temperature ◽  
P Wave ◽  
High Temperature Treatment ◽  
High Porosity ◽  
Compression Tests

High temperature treatment has a significant influence on the mechanical behavior and the associated microcracking characteristic of rocks. A good understanding of the thermal damage effects on rock behavior is helpful for design and stability evaluation of engineering structures in the geothermal field. This paper studies the mechanical behavior and the acoustic emission (AE) characteristic of three typical rocks (i.e., sedimentary, metamorphic, and igneous), with an emphasis on how the difference in rock type (i.e., porosity and mineralogical composition) affects the rock behavior in response to thermal damage. Compression tests are carried out on rock specimens which are thermally damaged and AE monitoring is conducted during the compression tests. The mechanical properties including P-wave velocity, compressive strength, and Young’s modulus for the three rocks are found to generally show a decreasing trend as the temperature applied to the rock increases. However, these mechanical properties for quartz sandstone first increase to a certain extent and then decrease as the treatment temperature increases, which is mainly attributed to the high porosity of quartz sandstone. The results obtained from stress–strain curve, failure mode, and AE characteristic also show that the failure of quartz-rich rock (i.e., quartz sandstone and granite) is more brittle when compared with that of calcite-rich rock (i.e., marble). However, the ductility is enhanced to some extent as the treatment temperature increases for all the three examined rocks. Due to high brittleness of quartz sandstone and granite, more AE activities can be detected during loading and the recorded AE activities mostly accumulate when the stress approaches the peak strength, which is quite different from the results of marble.

scholarly journals Nanocrystalline composites in TiO2 and SnO2 system for ammonia resistance sensors

2018 ◽  
Vol 12 (3) ◽  
pp. 240-247
Author(s):  
Anna Szczygielska ◽  
Zbigniew Pędzich ◽  
Wojciech Maziarz
Keyword(s):  
Phase Composition ◽  
Sol Gel ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Medium Size ◽  
X Ray Diffraction ◽  
Nanocrystalline Tio2 ◽  
Tio2 Anatase ◽  
Transmission Electron ◽  
Sorption Method

This work describes the production of nanocrystalline TiO2 and SnO2 oxides, as well as their nanocomposites (containing 26.9, 58.7 and 79.0wt.% of SnO2) with two-stage sol-gel method combined with high temperature treatment. The phase composition and medium size crystallites were determined using X-ray diffraction analysis (XRD) and revealed that the nanocomposites crystallize in tetragonal structures of TiO2 - anatase and SnO2 - cassiterite. Specific surface area of the nanopowders, measured using sorption method (BET), changed from 42.1 to 160.8m2/g. The morphology of the nanopowders was observed using transmission electron microscope (TEM). As indicated by TEM images, the manufactured nanopowders were well crystallized and consisted of small, spherical grains. The obtained nanopowders were also tested for NH3 gas detection application. The presented method of nanopowders synthesis enables to obtain nanocrystalline TiO2 and SnO2 oxides, as well as composites from TiO2-SnO2 of known and controlled chemical and phase composition. It also enables to obtain composites used for gas sensors. The sensor made of composite containing 58.7wt.% of SnO2 exhibited the best NH3 sensing features.

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