scholarly journals The Effect of Excess Carbon on the Crystallographic, Microstructural, and Mechanical Properties of CVD Silicon Carbide Fibers

2006 ◽  
Vol 982 ◽  
Author(s):  
James V Marzik ◽  
William J. Croft ◽  
Richard J. Staples ◽  
Warren J. MoberlyChan
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Silicon Carbide ◽  
Elastic Modulus ◽  
Chemical Vapor ◽  
High Strength ◽  
Excess Carbon ◽  
X Ray ◽  
Silicon Carbide Fibers ◽  
Sic Fiber

ABSTRACTSilicon carbide (SiC) fibers made by chemical vapor deposition (CVD) are of interest for organic, ceramic, and metal matrix composite materials due their high strength, high elastic modulus, and retention of mechanical properties at elevated processing and operating temperatures. The properties of SCS-6™ silicon carbide fibers, which are made by a commercial process and consist largely of stoichiometric SiC, were compared with an experimental carbon-rich CVD SiC fiber, to which excess carbon was added during the CVD process. The concentration, homogeneity, and distribution of carbon were measured using energy dispersive x-ray spectroscopy (SEM/EDS). The effect of excess carbon on the tensile strength, elastic modulus, and the crystallographic and microstructural properties of CVD silicon carbide fibers was investigated using tensile testing, x-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

TEM of grain growth and phase transformations during creep of SCS-6 silicon carbide fibers

1995 ◽  
Vol 53 ◽  
pp. 350-351
Author(s):  
L. A. Giannuzzi ◽  
C. A. Lewinsohn ◽  
C. E. Bakis ◽  
R. E. Tressler
Keyword(s):  
Silicon Carbide ◽  
Creep Rate ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Primary Creep ◽  
Excess Carbon ◽  
Silicon Carbide Fibers ◽  
Sic Fiber ◽  
Carbon Core ◽  
Grain Width

The SCS-6 SiC fiber is a 142 μm diameter fiber consisting of four distinct regions of βSiC. These SiC regions vary in excess carbon content ranging from 10 a/o down to 5 a/o in the SiC1 through SiC3 region. The SiC4 region is stoichiometric. The SiC sub-grains in all regions grow radially outward from the carbon core of the fiber during the chemical vapor deposition processing of these fibers. In general, the sub-grain width changes from 50nm to 250nm while maintaining an aspect ratio of ~10:1 from the SiC1 through the SiC4 regions. In addition, the SiC shows a <110> texture, i.e., the {111} planes lie ±15° along the fiber axes. Previous has shown that the SCS-6 fiber (as well as the SCS-9 and the developmental SCS-50 μm fiber) undergoes primary creep (i.e., the creep rate constantly decreases as a function of time) throughout the lifetime of the creep test.

Application of chemical vapor deposited yttria for the protection of silicon carbide fibers in a SiC/Ni3Al composite

1990 ◽  
Vol 5 (11) ◽  
pp. 2706-2717 ◽  
Author(s):  
D. J. Larkin ◽  
L. V. Interrante ◽  
A. Bose
Keyword(s):  
Silicon Carbide ◽  
Nickel Aluminide ◽  
Chemical Vapor ◽  
Degradation Process ◽  
Auger Spectroscopy ◽  
Silicon Carbide Fibers ◽  
Sic Fiber ◽  
Chemical Vapor Deposited ◽  
Volatile Products ◽  
Before And After

A CVD process has been developed for coating Textron-Avco SCS-6 SiC fiber with yttria. Both Y(fod)3·H2O and Y(thd)3 (fod = 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedionato; thd = 2,2,6,6-tetramethyl-3,5-heptanedionato) were examined as potential Y2O3 CVD precursors. Analysis of the deposits by Auger spectroscopy indicated significant F and C'incorporation in the case of Y(fod)3 · H2O whereas, under appropriate conditions, Y(thd)3 gave a deposit which was essentially free of C and other impurities. GCFTIR analysis of the volatile products of the CVD process indicated isobutylene, tetrafluoroethylene, 1,1-difluoroethylene, fluoroform, and fluoroethylene for Y(fod)3 · H2O and mainly isobutylene and propylene for Y(thd)3. The precursor Y(thd)3 was chosen to deposit 1–2 μm of yttria on short lengths of silicon carbide fibers. The coated fibers were then incorporated into a nickel aluminide (Ni3Al) matrix by reactive sintering, with yttria affording protection from the known SiC + 2Ni ⇉ Ni2Si + C degradation process. The SiC/Ni3Al composites, before and after annealing at 1000 °C for up to 100 h, were studied by using SEM and EMPA to determine the extent of reaction. With the exception of certain portions of the fibers that were inadequately coated with yttria, complete protection of the fibers was indicated.

Effect of Electrochemical Treatment on the Surface Structure and Tensile Strength of Carben Coated CVD SiC Fiber

2007 ◽  
Vol 546-549 ◽  
pp. 1571-1574
Author(s):  
L. Ji ◽  
N.L. Shi ◽  
Rui Yang
Keyword(s):  
Tensile Strength ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Temperature Stability ◽  
High Strength ◽  
Electrochemical Treatment ◽  
X Ray ◽  
Sic Fiber ◽  
Carbon Coated ◽  
Anodic Oxidation Method

CVD (chemical vapor deposition) SiC continuous fiber is used as reinforcement of metal matrix composites because of its high strength, high stiffness and elevated temperature stability. In this work, anodic oxidation method was used to treat the surface of carbon coated SiC fiber. Then the surface of treated fiber was compared with untreated one by scan electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). SiC was detected on the surface of untreated carbon-rich coating. It is proved by XPS that SiC was transformed into SiO2 after treatment. About 100~200nm thick oxidation layer was detected on the surface of carbon-rich coating and the structure of double coatings formed. Because the surface of fiber became smooth and the tensile stress on it was relaxed after treatment, the tensile strength of fiber was improved by 8%~20% average and the dispersing ratio of it was reduced.

STUDY OF MECHANICAL PROPERTIES AND FRACTURE MODE OF ALUMINA-SILICON CARBIDE NANOCOMPOSITES

2012 ◽  
Vol 05 ◽  
pp. 551-558 ◽  
Author(s):  
A. RAHIMNEZHAD YAZDI ◽  
H.R. BAHARVANDI ◽  
H. ABDIZADEH ◽  
N. EHSANI
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Silicon Carbide ◽  
Flexural Strength ◽  
Fracture Mode ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sic Particles ◽  
Scanning Electron

In this study Al 2 O 3- SiC nanocomposites have been fabricated by mixing of alumina and silicon carbide nano powders, followed by hot pressing at 1700°C. The mechanical properties and fracture mode of Al 2 O 3- SiC nanocomposites containing different volume fractions (5, 10 and 15%) of nano scale SiC particles were investigated and compared with those of alumina. Al 2 O 3- SiC powders were prepared by planetary milling in isopropanol. Fracture mode of specimens was investigated by means of scanning electron microscopy. Nanocomposites were tougher than alumina when they were hot pressed at the same temperature, and the values of nanocomposite's flexural strength and hardness were higher than those of alumina. Flexural strength, hardness and fracture toughness of the nanocomposites increase by increasing the volume percent of SiC up to 10% and then decrease slightly. The Scanning electron microscopy observations showed that fracture mode changes from intergranular for alumina to transgranular for nanocomposites. Finally X-ray diffraction analysis couldn't detect any chemical reactions between Al 2 O 3 and SiC particles.

Effects of Hot Isostatic Pressing (HIP) on Microstructure and Mechanical Properties of K403 Nickel-Based Superalloy

2016 ◽  
Vol 35 (5) ◽  
pp. 463-471 ◽  
Author(s):  
Haocheng Zhang ◽  
Anqiang Wang ◽  
Zhixun Wen ◽  
Zhufeng Yue ◽  
Chengjiang Zhang
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Elastic Modulus ◽  
Volume Fraction ◽  
Cast Alloy ◽  
Hot Isostatic Pressing ◽  
X Ray ◽  
Nickel Based Superalloy ◽  
Nanoindentation Experiment ◽  
Scanning Electron

AbstractThe microstructure of as-cast and as-HIPed (hot isostatic pressed) K403 superalloy was investigated using a scanning electron microscopy (SEM), as component analysis was conducted by energy dispersive x-ray spectrometer (EDS). It was found that the microstructure of the alloy was improved significantly through HIP. Firstly, the microporosity and micropores in as-cast alloy were ameliorated effectively and the morphology of grains tended to be uniform. Moreover, the morphology of carbides at grain boundaries transformed from thread-like to granular. Uppermost, the size, shape and volume fraction of γ′ phase were significantly optimized and γ′ precipitates in two different sizes were generated in matrix. Nanoindentation experiment was then carried out to obtain the nanohardness and elastic modulus of as-cast and as-HIPed K403 superalloy. The results revealed an obvious increase in both nanohardness and elastic modulus after HIP. Conclusions could be drawn from the research that HIP could improve the microstructure of as-cast K403 superalloy, which could enhance the mechanical properties of the alloy positively.

Synthesis of Silicon Carbide Nanotubes by Chemical Vapor Deposition

2007 ◽  
Vol 7 (2) ◽  
pp. 647-652 ◽  
Author(s):  
Zhengfang Xie ◽  
Deliang Tao ◽  
Jiqing Wang
Keyword(s):  
Electron Microscopy ◽  
Silicon Carbide ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Wall Structure ◽  
Outer Diameter ◽  
X Ray ◽  
Silicon Carbide Nanotubes ◽  
Gaseous Source

Silicon carbide nanotubes (SiCNTs) were directly synthesized by chemical vapor deposition (CVD) in the paper. Methyltrichlorosilane (MTS) was selected as the SiC gaseous source and, ferrocence and thiophene as the catalyst and the cocatalyst, respectively. The influences of reaction temperature, contents of catalyst and cocatalyst, and content of gaseous source on the morphologies of the products were investigated, respectively. The products were identified by high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray (EDX), respectively. The synthesis of SiCNTs by CVD suggested a condition-dependent process. Novel SiCNTs, with 20∼80 nm in outer diameter and 15∼35 nm in inner diameter, respectively, were observed. The wall structure similar to that of carbon nanotubes was not found for the SiCNTs.

Analytical Electron Microscopy of a Polymer Blend

1985 ◽  
Vol 43 ◽  
pp. 80-81
Author(s):  
T. Haddock ◽  
S.J. Krause ◽  
S. Kumar ◽  
W.W. Adams
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Polymer Blend ◽  
Analytical Electron Microscopy ◽  
High Strength ◽  
X Ray ◽  
Analytical Electron ◽  
Flexible Coil ◽  
Electron Energy Loss ◽  
Beam Damage

A polymer blend which is composed of poly-p-phenylene benzobisthiazole (PBT) and poly-2,5(6)benzimidazole (ABPBI) has been processed into both a phase-separated material and a “molecular composite”. In the molecular composite, the PBT and ABPBI components are dispersed at a scale finer than 3 nm. This results in high mechanical properties as the rod-like, high strength PBT reinforces the flexible-coil ABPBI matrix. In the phase- separated blend, micron-sized aggregates form within a more ductile matrix. This study qualitatively examines the structure and composition of the phase- separated 20% PBT / 80% ABPBI blend using the analytical electron microscopy (AEM) techniques of energy dispersive x-ray spectroscopy (EDS), electron energy loss spectroscopy (EELS), and microdiffraction. Beam damage of the components is also considered.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

scholarly journals Features of the hydration process of the modified blended cement for fiber cement panels

2018 ◽  
Vol 170 ◽  
pp. 03030 ◽  
Author(s):  
Rustem Mukhametrakhimov ◽  
Liliya Lukmanova
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Blended Cement ◽  
Physical And Mechanical Properties ◽  
Hydration Process ◽  
Cement Matrix ◽  
X Ray Diffraction ◽  
Structure Form ◽  
Silicate Phase ◽  
X Ray

The paper studies features of the hydration process of the modified blended cement for fiber cement panels (FCP) using differential thermal analysis, X-ray diffraction analysis, electron microscopy and infrared spectroscopy. It is found that deeper hydration process in silicate phase, denser and finer crystalline structure form in fiber cement matrix based on the modified blended cement. Generalization of this result to the case of fiber cement panels makes it possible to achieve formation of a denser and homogeneous structure with increased physical and mechanical properties.

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