Oxidation Behavior of Aluminide Coated Ti-Al-Cr-Nb-Zr-Y Alloys at High Temperatures

2015 ◽  
Vol 227 ◽  
pp. 345-348 ◽  
Author(s):  
Eddy Basuki ◽  
Djoko Prajitno ◽  
Pawawoi
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Aluminide Coating ◽  
Diffraction Method ◽  
Complex Oxides ◽  
Intermetallic Alloy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Interdiffusion Process ◽  
Pack Aluminizing

In this study the oxidation behavior of diffusion aluminide coating containing layers of TiAl3 and TiAl2, develop on a substrate of Zr-Y doped α2-Ti3Al/γ-TiAlCrNb intermetallic alloy using pack aluminizing method, was investigated isothermally at 800°C, 900°C, and 1000°C under atmospheric air pressure. The pack cementation was carried out at 850°C for 25 hours in a pack containing 20%-wt Al, 2%-wt NH4Cl, and 78%-wt Al2O3.The phases in the coatings and oxide layers were examined by optical and scanning electron microscopy as well as X-ray diffraction method, while chemical composition of the oxides and phases were examined with EDS attached on the SEM. The experimental results showed that the addition of Zr and Y increases the oxidation resistance of the coating by formation of complex oxides mainly of Al2O3 at the coating surfaces and sub-surface. Combination of oxidation and interdiffusion process cause transformation of TiAl3 layer to TiAl2 that decrease the oxidation resistance through the formation of TiO2 rod crystals on the junction between TiAl2 and Al2O3 in the outer layer.

Oxidation Behavior of Rh-xTi Refractory Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 721-724
Author(s):  
Rabindra Mahapatra ◽  
A.W. Davis
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Complex Oxides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Refractory Alloys ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
Xrd Techniques ◽  
Lower Oxidation

In this paper we report the oxidation behavior of Rh-xTi (x = 15 & 20 atomic percent) alloys isothermally exposed in air between 1000 and 1300 oC up to a period of 312 hours. The weight gain of arc-melted Rh-15Ti and Rh-20Ti alloys as a function of time was monitored. Results indicate that the oxidation resistance of Rh-15Ti and Rh-20Ti alloys at 1000 and 11000 C is similar to that of advanced nickel-base superalloys. However, these alloys show excellent oxidation resistance beyond the operational limit for nickel-base superalloys. Optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD) techniques were used to study the microstructure and morphology of the oxides. These alloys oxidize by forming TiO2 and Rh2O3 complex oxides. The Rh-20Ti alloys displayed lower oxidation resistance than Rh-15Ti alloys.

Effects of SiC on Oxidation Behavior of ZrB2-Based Composites with MoSi2 and SiC Additives

2014 ◽  
Vol 602-603 ◽  
pp. 457-462 ◽  
Author(s):  
Shu Qi Guo
Keyword(s):  
Weight Gain ◽  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Bulk Material ◽  
Sample Surface ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scale Layer ◽  
Exposure Temperature ◽  
Reactive Mixture

In this study, oxidation behavior of ZrB2-MoSi2-SiC composite was investigated in the hot-pressed 5-20 vol% SiC-containing ZrB2-20 vol% MoSi2-based composites which were exposed to dry air between 1100°C and 1500°C up to 10 hours. The effects of SiC additive on the oxidation behavior were assessed. Experimental results showed that the weight gain due to oxidation exposure in air increased with increasing exposure temperature and exposure time. Parabolic oxidation behavior was observed for all the compositions composites. On the other hand, the weight gain decreased with increasing amount of SiC added. The addition of SiC improved the oxidation resistance of the composites, and the improvement was enhanced with increasing amount of SiC added. In addition, X-ray diffraction was used to identify major crystalline phases present in both the as-received and the post-oxidized composites. The oxidized sample surface was characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The microstructure of the post-oxidized composites consisted of two characteristic regions: oxidized reactive region and unreactive bulk material region. Furthermore, the oxidized reactive region divided into an outermost dense silica-rich scale layer and oxidized reactive mixture layer. The improvement of the oxidation resistance due to the addition of SiC is associated with the presence of the thicker dense outermost scale layer which inhibited inward diffusion of oxygen through it.

scholarly journals Isothermal Oxidation Behavior of Novel Al2O3 / NiCrAlY / Ti3Al System at 850�C

2020 ◽  
Vol 71 (5) ◽  
pp. 106-116
Author(s):  
Alexandra Banu ◽  
Alexandru Paraschiv ◽  
Simona Petrescu ◽  
Irina Atkinson ◽  
Elena Maria Anghel ◽  
...  
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Mass Gain ◽  
Isothermal Oxidation ◽  
Thermal Barrier ◽  
The Novel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Aerospace Applications

The novel Al2O3 / NiCrAlY /alfa2-Ti3Al system obtained by APS technique was tested against long (500h) isothermal oxidation at 850�C in air for prospective use in aerospace applications. EDX-SEM, X-ray diffraction (XRD) and Raman investigations were conducted to substantiate structural, textural and mass gain modifications underwent by the Al2O3 / NiCrAlY /alfa2-Ti3Al system in comparison with bare alfa2-Ti3Al and NiCrAlY /alfa2-Ti3Al system. Improved oxidation resistance of the double-coated system is based on moderate oxygen and thermal barrier role played by the mixture of delta - and alfa-Al2O3 present in the top ceramic coat.

scholarly journals Growth of sillenite Bi12FeO20 single crystals: structural, thermal, optical, photocatalytic features and first principle calculations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Durga Sankar Vavilapalli ◽  
Ambrose A. Melvin ◽  
F. Bellarmine ◽  
Ramanjaneyulu Mannam ◽  
Srihari Velaga ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Diffraction Method ◽  
Lattice Parameter ◽  
First Principle ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Principle Calculations ◽  
Photodegradation Efficiency

AbstractIdeal sillenite type Bi12FeO20 (BFO) micron sized single crystals have been successfully grown via inexpensive hydrothermal method. The refined single crystal X-ray diffraction data reveals cubic Bi12FeO20 structure with single crystal parameters. Occurrence of rare Fe4+ state is identified via X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The lattice parameter (a) and corresponding molar volume (Vm) of Bi12FeO20 have been measured in the temperature range of 30–700 °C by the X-ray diffraction method. The thermal expansion coefficient (α) 3.93 × 10–5 K−1 was calculated from the measured values of the parameters. Electronic structure and density of states are investigated by first principle calculations. Photoelectrochemical measurements on single crystals with bandgap of 2 eV reveal significant photo response. The photoactivity of as grown crystals were further investigated by degrading organic effluents such as Methylene blue (MB) and Congo red (CR) under natural sunlight. BFO showed photodegradation efficiency about 74.23% and 32.10% for degrading MB and CR respectively. Interesting morphology and microstructure of pointed spearhead like BFO crystals provide a new insight in designing and synthesizing multifunctional single crystals.

scholarly journals Study of Corrosion Resistance and Degradation Mechanisms in LiTiO2-Li2TiO3 Ceramic

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 753
Author(s):  
Dmitriy Shlimas ◽  
Artem L. Kozlovskiy ◽  
Maxim Zdorovets
Keyword(s):  
Degradation Mechanism ◽  
Diffraction Method ◽  
Large Mass ◽  
Time Frame ◽  
X Ray Diffraction ◽  
Acidic Media ◽  
X Ray ◽  
Mass Losses ◽  
The Stability ◽  
Thermal Sintering

The interest in lithium-containing ceramics is due to their huge potential as blanket materials for thermonuclear reactors for the accumulation of tritium. However, an important factor in their use is the preservation of the stability of their strength and structural properties when under the influence of external factors that determine the time frame of their operation. This paper presents the results of a study that investigated the influence of the LiTiO2 phase on the increasing resistance to degradation and corrosion of Li2TiO3 ceramic when exposed to aggressive acidic media. Using the X-ray diffraction method, it was found that an increase in the concentration of LiClO4·3H2O during synthesis leads to the formation of a cubic LiTiO2 phase in the structure as a result of thermal sintering of the samples. During corrosion tests, it was found that the presence of the LiTiO2 phase leads to a decrease in the degradation rate in acidic media by 20–70%, depending on the concentration of the phase. At the same time, and in contrast to the samples of Li2TiO3 ceramics, for which the mechanisms of degradation during a long stay in aggressive media are accompanied by large mass losses, for the samples containing the LiTiO2 phase, the main degradation mechanism is pitting corrosion with the formation of pitting inclusions.

Study of the quality of GaAs thin film on Si substrate by X-ray diffraction method

1990 ◽  
Vol 7 (7) ◽  
pp. 308-311
Author(s):  
Li Chaorong ◽  
Mai Zhenhong ◽  
Cui Shufan ◽  
Zhou Junming ◽  
Yutian Wang
Keyword(s):  
Thin Film ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
Si Substrate ◽  
X Ray

A New X‐Ray Diffraction Method for Studying Imperfections of Crystal Structure in Polycrystalline Specimens

1951 ◽  
Vol 22 (5) ◽  
pp. 665-672 ◽  
Author(s):  
Alfred J. Reis ◽  
Jerome J. Slade ◽  
Sigmund Weissmann
Keyword(s):  
Crystal Structure ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
X Ray

The Research about Oxidation Kinetics of Ti60 Alloy and Ni-Co-Cr-Al-Y-Si Coating on Surface

2011 ◽  
Vol 189-193 ◽  
pp. 743-746
Author(s):  
Jian Feng Li ◽  
Li Zhi Guo ◽  
Guo Qing Li
Keyword(s):  
Oxidation Resistance ◽  
X Ray Diffraction ◽  
Surface Appearance ◽  
X Ray ◽  
Good Oxidation Resistance ◽  
Ion Plating ◽  
Alloy Oxidation ◽  
Resistance Performance ◽  
Kinetics Of ◽  
Electronic Microscope

This article summarized depositing craft of the superficial coatings (Ni-Co-Cr-Al-Y-Si) on the Ti60 alloy (Ti-6.5Al-4.2Sn-4Zr-0.6Si) with arc ion plating technology and the oxidation behavior under 600~750 . The X-ray diffraction (XRD) and the scanning electronic microscope (SEM) were used to analyze the surface appearance, the structure and the ingredient conducts of non-coating Ti60 alloy. The contrast shows that the coatings have good protection to Ti60 alloy. The result indicated that the coating has the good oxidation resistance performance under 600°C , 650°C and 750°C . Coated Ti60 alloy oxidation resistance is markly improved. The circulation oxidation dynamics curve basically conforms to the parabola rule.

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