Oxidation Kinetics and Strength Versus Scale Thickness for Hi-Nicalon™ -S SiC Fiber

2010 ◽  
pp. 105-112 ◽  
Author(s):  
R. S. Hay ◽  
G. Fair ◽  
E. Urban ◽  
J. Morrow ◽  
J. Somerson ◽  
...  
Keyword(s):  
Oxidation Kinetics ◽  
Scale Thickness ◽  
Sic Fiber

Effects of Si Content on the Oxidation Behavior of Fe–Si Alloys in Air

2011 ◽  
Vol 696 ◽  
pp. 126-131 ◽  
Author(s):  
Takumi Nishimoto ◽  
Kazuhiko Honda ◽  
Yasumitsu Kondo ◽  
Kenichi Uemura
Keyword(s):  
Oxide Scale ◽  
Cross Sections ◽  
Oxidation Kinetics ◽  
Oxidation Behavior ◽  
Elemental Distribution ◽  
Oxide Scales ◽  
Scale Thickness ◽  
Internal Oxidation Zone ◽  
Diffusion Controlled ◽  
Si Content

The oxidation behavior of Fe–Si alloys at 1073K in air was investigated. The oxidation kinetics described by the parabolic rate law of diffusion controlled oxidation and the oxidation rate decrease with the increasing Si content. Fe-Si alloys were oxidized for different times at 1073K to obtain the same scale thickness of approximately 30μm. Observations of scale cross-sections indicated the structure of oxide scale and elemental distribution in oxide scales strongly depends on Si content. The oxide scale on Fe-Si alloys with low Si content consisted of three layers with an outer Fe2O3, an intermediate Fe3O4 and an inner FeO and some voids were formed in Fe3O4 and FeO layers. The Si-rich oxide layer was formed at the scale/alloy interface of Fe-Si alloys with high Si content. Furthermore, the amount of internal oxidation zone increased with the increasing Si content. Observations of scale cross-sections indicated that the structure of oxide scale and elemental distribution in oxide scale strongly depend on Si content.

Oxidation of Experimental Ti-Si-Al Based Alloys

2016 ◽  
Vol 258 ◽  
pp. 391-394
Author(s):  
Serhii Tkachenko ◽  
Oleg Datskevich ◽  
Zdeněk Spotz ◽  
Karel Dvořák ◽  
Leonid Kulak ◽  
...  
Keyword(s):  
High Temperature ◽  
Titanium Alloys ◽  
Oxide Scale ◽  
Oxidation Kinetics ◽  
High Strength ◽  
X Ray Diffraction ◽  
Scale Thickness ◽  
Alpha Case ◽  
Good Potential ◽  
Experimental Findings

Despite the fact that conventional high temperature titanium alloys possess a good combination of low weight, high strength and good corrosion resistance, their operational temperatures do not exceed 540-600 °C, since at higher temperatures they suffer from extensive oxidation, scaling and formation of a brittle oxygen-reach diffusion layer on their surface, so-called ‘apha-case’. The alloying with silicon was regarded as a promising way to raise the working temperatures of titanium alloys, since silicon is known to improve oxidation resistance, oxide scale adherence and high temperature creep behavior of titanium without noticeable deterioration of its ductility. The present paper was focused on studying of the oxidation kinetics and the formation of oxide scale and alpha-case layers on a series of experimental Ti−Al−Si based alloys, additionally alloyed with zirconium and tin. The oxidation kinetics of the experimental alloys upon exposure in air at 700 °С for up to 240 hours was examined and compared with that of commercially available Ті−6242 alloy. The oxide scale thickness, its phase composition and crystal morphology were characterized using X-ray diffraction and scanning electron microscopy (SEM), while the alpha-case layer was analyzed using SEM and microhardness measurements. According to the experimental findings, the experimental Ti−Al−Si based alloys demonstrated a good potential for their use at high temperatures.

The Effects of Mo Addition on the Structure of Scales Formed in High Si Steel at 1150°C

2012 ◽  
Vol 576 ◽  
pp. 442-445
Author(s):  
Ahmad Zaki Mohd Zainal ◽  
Kazuya Kurokawa
Keyword(s):  
Weight Gain ◽  
Oxidation Kinetics ◽  
Outward Diffusion ◽  
Scale Thickness ◽  
Lower Weight ◽  
Highest Weight ◽  
Internal Oxidation Zone ◽  
Base Steel ◽  
Lower Weight Gain ◽  
Mo Content

High Si steels (base steel and with addition of 0.1, 0.3, 0.5mass% Mo) were oxidized in a N2-3%O2-20%H2O atmosphere at 1150oC for 0.3-10.8ks. The oxidation kinetics showed that base steel has the highest weight gain. In contrast, 0.5Mo has the lowest weight gain. From SEM results, the scale thickness decreased as Mo content increased. Distribution of alloying elements showed that Mo is enriched in internal oxidation zone (IOZ) and played a role in slowing the outward diffusion of Fe, thus, producing a thinner Fe oxide scale and lower weight gain.

scholarly journals Examining oxidation in β-NiAl and β-NiAl+Hf alloys by stochastic cellular automata simulations

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Indranil Roy ◽  
Pratik K. Ray ◽  
Ganesh Balasubramanian
Keyword(s):  
Cellular Automata ◽  
Grain Boundaries ◽  
Oxide Scale ◽  
Oxidation Kinetics ◽  
Basic Principles ◽  
Stochastic Cellular Automata ◽  
Scale Thickness ◽  
Alloy Oxidation ◽  
Ca Model ◽  
Kinetics Of

AbstractWe present results from a stochastic cellular automata (CA) model developed and employed for examining the oxidation kinetics of NiAl and NiAl+Hf alloys. The rules of the CA model are grounded in diffusion probabilities and basic principles of alloy oxidation. Using this approach, we can model the oxide scale thickness and morphology, specific mass change and oxidation kinetics as well as an approximate estimate of the stress and strains in the oxide scale. Furthermore, we also incorporate Hf in the grain boundaries and observe the “reactive element effect”, where doping with Hf results in a drastic reduction in the oxidation kinetics concomitant with the formation of thin, planar oxide scales. Interestingly, although we find that grain boundaries result in rapid oxidation of the undoped NiAl, they result in a slower-growing oxide and a planar oxide/metal interface when doped with Hf.

scholarly journals Oxidation of SiC Fiber-Reinforced SiC Matrix Composites with a BN Interphase

2011 ◽  
Vol 696 ◽  
pp. 342-347 ◽  
Author(s):  
Elizabeth J. Opila ◽  
Meredith K. Boyd
Keyword(s):  
Oxidation Kinetics ◽  
Thermal Protection ◽  
Microstructural Characterization ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Sic Fiber ◽  
Silica Scale ◽  
Partial Pressures ◽  
Oxygen Ingress ◽  
Kinetics Of

The oxidation kinetics of SiC fiber-reinforced SiC matrix composites with a BN interphase (SiC/BN/SiC) and the constituent fibers was characterized by thermogravimetric analysis and microstructural characterization at temperatures (816-1538°C) and oxygen partial pressures (0.1% to 5% O2) relevant to the hypersonic flight and re-entry environments. TGA of the SiC fibers showed that oxidation of the thin BN surface layer led to initially rapid oxidation kinetics and formation of a relatively thick silica scale at very short times under most test conditions. At longer times the fiber oxidation kinetics were representative of silica formation on pure SiC. Oxidation of the composites was conducted on coupons with the SiC seal coat removed on one edge to simulate damage to the composite, allowing ingress of oxygen to the fiber tows. Microscopy was conducted to determine the distance of oxygen ingress into the coupon. At the lower temperatures and oxygen partial pressures the exposed edge did not seal off by silica formation, yet the BN interphase areas were only minimally oxidized. At the intermediate temperatures silica formed at the exposed surface limiting further oxidation of the exposed fibers and BN interphase areas. Finally at the highest temperature and lowest oxygen partial pressure, active oxidation of SiC occurred for both the fibers and coupons resulting in irregular material attack. Implications for use of SiC/BN/SiC materials for hypersonic vehicle thermal protection systems are summarized.

Oxidation Behavior of a Disk Powder Metallurgy Superalloy

2017 ◽  
Vol 898 ◽  
pp. 467-475
Author(s):  
Kai Xin Dong ◽  
Chao Yuan ◽  
Shuang Gao ◽  
Jian Ting Guo
Keyword(s):  
Oxidation Kinetics ◽  
Oxidation Behavior ◽  
Isothermal Oxidation ◽  
Spray Forming ◽  
X Ray Diffraction ◽  
Temperature Range ◽  
Scale Thickness ◽  
Aluminum Ions ◽  
Gain Measurement ◽  
Oxidation Behaviors

Oxidation behaviors of a spray-forming disk superalloy LSHR were investigated in the temperature range of 750-900°C. The composition and morphology of oxidation scales were investigated by X-ray diffraction (XRD), scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS), and electron probe microanalysis (EPMA). Oxidation kinetics was studied by the means of isothermal oxidation testing in air and weight gain measurement. The oxide scales were composed of Cr2O3, TiO2, Al2O3 and a small amount of NiCr2O4. The experiment results showed that oxidation kinetics and oxide layers followed a square power law as time extended from 750 to 900°C. With the oxidation temperature increasing, external scale thickness, and internal oxidation zone increased. The oxidation behavior was controlled by the diffusion of oxygen, chromium, titanium, and aluminum ions, as chromium, titanium, and aluminum ions diffused outward and oxygen diffused inward. Based on the standard HB5258-2000 spray-forming LSHR exhibited an excellent oxidation resistance in the whole test temperature range.

scholarly journals Synthesis and Properties of Orthorhombic MoAlB Coatings

Coatings ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 510 ◽  
Author(s):  
Achenbach ◽  
Sahu ◽  
Völker ◽  
Hans ◽  
Primetzhofer ◽  
...  
Keyword(s):  
Oxidation Kinetics ◽  
Alumina Scale ◽  
Scanning Transmission Electron Microscope ◽  
Potential Candidate ◽  
X Ray ◽  
Scale Thickness ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The One ◽  
Kinetics Of

MoAlB is a potential candidate for high-temperature application since a dense, adherent alumina scale is formed. While, based on X-ray diffraction investigations, the formation of phase pure orthorhombic MoAlB coatings is observed, energy dispersive X-ray spectroscopy carried out in a scanning transmission electron microscope reveals the presence of Al-rich and O-rich regions within the MoAlB matrix. The oxidation kinetics of coatings and bulk is similar to the scale thickness formed on the MoAlB coating after oxidation at 1200 °C for 30 min is similar to the one extrapolated for bulk MoAlB. Furthermore, the oxidation kinetics of MoAlB coatings is significantly lower than the one reported for bulk Ti2AlC. Finally, the elastic properties measured for the as-deposited coatings are consistent ab initio predictions.

TEM characterization of reaction zone in a SiC fiber-reinforced titanium alloy

1988 ◽  
Vol 46 ◽  
pp. 738-739
Author(s):  
G. Das ◽  
R. E. Omlor
Keyword(s):  
Titanium Alloys ◽  
Reaction Zone ◽  
Carbon Layer ◽  
Fiber Reinforced ◽  
Reaction Products ◽  
Sic Fibers ◽  
Sic Fiber ◽  
The Matrix ◽  
Immense Potential

Fiber reinforced titanium alloys hold immense potential for applications in the aerospace industry. However, chemical reaction between the fibers and the titanium alloys at fabrication temperatures leads to the formation of brittle reaction products which limits their development. In the present study, coated SiC fibers have been used to evaluate the effects of surface coating on the reaction zone in the SiC/IMI829 system.IMI829 (Ti-5.5A1-3.5Sn-3.0Zr-0.3Mo-1Nb-0.3Si), a near alpha alloy, in the form of PREP powder (-35 mesh), was used a茸 the matrix. CVD grown AVCO SCS-6 SiC fibers were used as discontinuous reinforcements. These fibers of 142μm diameter contained an overlayer with high Si/C ratio on top of an amorphous carbon layer, the thickness of the coating being ∽ 1μm. SCS-6 fibers, broken into ∽ 2mm lengths, were mixed with IMI829 powder (representing < 0.1vol%) and the mixture was consolidated by HIP'ing at 871°C/0. 28GPa/4h.

Deformation at interfaces of Ti-6Al-4V/SiC fiber composites

1992 ◽  
Vol 50 (1) ◽  
pp. 158-159
Author(s):  
Warren J. Moberly ◽  
Daniel B. Miracle ◽  
S. Krishnamurthy
Keyword(s):  
Thermal Stresses ◽  
Load Transfer ◽  
Coefficient Of Thermal Expansion ◽  
Hot Isostatic Pressing ◽  
Matrix Composites ◽  
Ongoing Research ◽  
Aerospace Applications ◽  
Sic Fiber ◽  
The Matrix ◽  
Intermetallic Matrix Composites

Titanium-aluminum alloy metal matrix composites (MMC) and Ti-Al intermetallic matrix composites (IMC), reinforced with continuous SCS6 SiC fibers are leading candidates for high temperature aerospace applications such as the National Aerospace Plane (NASP). The nature of deformation at fiber / matrix interfaces is characterized in this ongoing research. One major concern is the mismatch in coefficient of thermal expansion (CTE) between the Ti-based matrix and the SiC fiber. This can lead to thermal stresses upon cooling down from the temperature incurred during hot isostatic pressing (HIP), which are sufficient to cause yielding in the matrix, and/or lead to fatigue from the thermal cycling that will be incurred during application, A second concern is the load transfer, from fiber to matrix, that is required if/when fiber fracture occurs. In both cases the stresses in the matrix are most severe at the interlace.

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