Non-Isothermal Method for Charactering the Oxidation Resistance Property of SiAlON Materials

2014 ◽  
Vol 1004-1005 ◽  
pp. 438-441
Author(s):  
Xiu Teng Wang ◽  
Pu Xiao ◽  
Bo Wang ◽  
Ling Xu ◽  
Ling Lin ◽  
...  
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Process ◽  
Antioxidant Properties ◽  
Isothermal Oxidation ◽  
Test Method ◽  
National Standard ◽  
Thermo Gravimetric ◽  
Isothermal Method ◽  
Thermo Gravimetric Analyzer ◽  
Oxidation Weight Gain

The oxidation resistance of SiAlONs is one important property. In our work we present a test method to characterize its anti-oxidation property with the non-isothermal oxidation process using Thermo Gravimetric Analyzer (TGA). The oxidation starting temperature (Ts), maximum oxidation rate temperature (Tm) and the value of the oxidation weight gain per unit area (Ga) are three key parameters to describe the antioxidant properties of the material. Experimental results prove this test method is easy and reasonable and it will be developed as the national standard of China.

Properties of Sputtered NiCrAlY Used for Protective Gun Tube Coatings

2011 ◽  
Vol 686 ◽  
pp. 613-617
Author(s):  
Jian Zhang ◽  
Cean Guo ◽  
Gang Zhang ◽  
Chong Rui Wang ◽  
Shi Ming Hao
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Oxidation Process ◽  
Complex Oxide ◽  
Isothermal Oxidation ◽  
Temperature Oxidation ◽  
Steel Balls ◽  
Steel Substrates ◽  
Micro Indentation

NiCrAlY coatings were deposited on CrNi3MoVA steel substrates by means of magnetron sputtering. The coatings were characterized in terms of their microstructure, hardness, friction coefficient, high-temperature oxidation resistance. Micro-indentation and tribometer testers were employed to measure the mechanical properties of NiCrAlY coatings and CrNi3MoVA steel. The results showed that the hardness of the coatings ranged from 5.7 to 5.9 GPa, with a higher value than that of CrNi3MoVA steel(4.1-4.3 GPa). The coefficient of steady-state friction of the coatings against 45-carbon-steel balls ranged from 0.35 to 0.40, with a lower value than that of CrNi3MoVA steel(0.63-0.68). The isothermal oxidation behavior at 850°C of the coatings were studied in comparison with CrNi3MoVA steel substrates. The results indicated that NiCrAlY coatings substantially increase the high-temperature oxidation resistance of CrNi3MoVA steel and the oxidation process was retarded mainly by the presence of outer complex oxide scales and a continuous Al2O3 inner layer on the coating.

Improvement in the Oxidation Resistance of β-SiAlON Ceramics Produced from Mechanically Milled Powders

2012 ◽  
Vol 18-19 ◽  
pp. 281-290
Author(s):  
Onur Eser ◽  
S. Kurama
Keyword(s):  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Isothermal Oxidation ◽  
High Energy ◽  
Particle Sizes ◽  
Temperature Oxidation ◽  
Dry Air ◽  
Milled Powders

In the present study the oxidation behavior of β-SiAlON ceramics, which were produced from conventional and high energy mechanical milled powders, was investigated. High energy mechanically milled powders have lower particle sizes ( 130 nm) than those of conventional powders (216 nm) and fully densified at lower temperatures with less amount of additives. The amount of additive is an important parameter to improve the high temperature oxidation resistance of SiAlON ceramics. The cyclic and isothermal oxidation tests were carried out at 1300 and 1400°C in dry air environment. The weight gain of oxidized samples was measured during the oxidation process. The alteration of oxide layer was analyzed by XRD and SEM. The results indicate that oxidation resistance of the samples produced from mechanically milled powders with less amount of additive is higher than that of conventional one. Therefore, β-SiAlON ceramics which were sintered at 100°C lower temperatures with less amount of additive (3.5 wt. % Y2O3), showed a better oxidation resistance.

scholarly journals Oxidation Behavior of Zr-based Amorphous Alloys at 400˚- 450˚C in Air

2019 ◽  
Vol 6 (1) ◽  
pp. 24
Author(s):  
Triwikantoro Triwikantoro ◽  
Romdhoni Graha Pribadi ◽  
Fatimatul Munawaroh
Keyword(s):  
Crystallization Temperature ◽  
Amorphous Alloys ◽  
Oxidation Behavior ◽  
Intermetallic Phase ◽  
Isothermal Oxidation ◽  
Thermo Gravimetric ◽  
Parabolic Law ◽  
Thermo Gravimetric Analyzer ◽  
Kinetics Of ◽  
Dominant Phase

<em><span lang="EN-US">The study of oxidation behavior of amorphous alloys based on Zirconium with 2 variations in composition was carried out: Zr<sub>64.5</sub>Cu<sub>17</sub>Ni<sub>11</sub>Al<sub>7.5 </sub>and Zr<sub>69.5</sub>Cu<sub>12</sub>Ni<sub>11</sub>Al<sub>7.5 </sub>at temperatures of 400 - 450˚C in air. Amorphous Zr-based alloys were thermally characterized using Differential Scanning Calorimeter (DSC) to determine the crystallization temperature and glass transition temperature. The oxidation characterization was carried out using a Thermo gravimetric Analyzer (TGA) at temperatures of 400, 425, and 450˚C for 4 hours in air. The phase analysis of the oxidation product was identified using X-Ra</span><span>y Diffaction</span><span lang="EN-US"> (XRD). Based on DSC data the crystallization temperature for Zr<sub>64.5</sub>Cu<sub>17</sub>Ni<sub>11</sub>Al<sub>7.5</sub> and Zr<sub>69.5</sub>Cu<sub>12</sub>Ni<sub>11</sub>Al<sub>7.5 </sub>is 426 and 442˚C respectively. The oxidation kinetics of the two alloys follow parabolic law and the oxidation rate increases with the addition of temperature. Oxides formed during isothermal oxidation in the Zr<sub>64.5</sub>Cu<sub>17</sub>Ni<sub>11</sub>Al<sub>7.5 </sub>and Zr<sub>69.5</sub>Cu<sub>12</sub>Ni<sub>11</sub>Al<sub>7.5</sub> alloys are t-ZrO<sub>2</sub> (tetragonal) as the dominant phase and ZrO<sub>2</sub> (monoclinic) and CuO as the minor phase. The intermetallic phase is also formed in both samples, t-Zr<sub>2</sub>Ni and Zr<sub>2</sub>Cu.</span></em>

A New Evaluation Index of Coke High Temperature Properties - Starting Reaction Temperature

2011 ◽  
Vol 194-196 ◽  
pp. 61-66
Author(s):  
Xu Zhang ◽  
Jian Liang Zhang ◽  
Hao Guo
Keyword(s):  
High Temperature ◽  
Standard Test ◽  
Test Method ◽  
National Standard ◽  
Evaluation Index ◽  
Thermo Gravimetric ◽  
High Temperature Properties ◽  
Reaction Index ◽  
Solution Loss Reaction ◽  
The Relationship

The coke reaction index and solution loss reaction starting temperature were tested by the thermo gravimetric test. According to the relationship between the temperature and the index，a new test method, which evaluates coke high temperature properties by the coke solution loss reaction starting temperature, was put forward. The new method has many merits such as expediently operation and reliable results compared with the method and results of the national standard test.

Study on Antioxidant Properties of the Carbon Fibers Coated with Oxide-Alumina-Silica Film

2014 ◽  
Vol 809-810 ◽  
pp. 535-539 ◽  
Author(s):  
Jia Lin Liu ◽  
Wang Xi Zhang ◽  
Jing Xian Han ◽  
Bao Yan Liang ◽  
Guo Rong Ma
Keyword(s):  
Phase Transition ◽  
Oxidation Resistance ◽  
Carbon Fibers ◽  
Sol Gel ◽  
Antioxidant Properties ◽  
Silica Coating ◽  
Isothermal Oxidation ◽  
Silica Film ◽  
Surface Appearance ◽  
Oxidation Experiment

An oxide-alumina-silicacoating which would to improve the oxidation resistance of carbon fibers was prepared by sol-gel method. XRD and SEM were used to characterize the surface appearance and phase transition about the carbon fibers with oxide-alumina-silica coating. The oxidation resistance of carbon fibers was also analyzed with the DSC-TG and the isothermal oxidation experiment. It was shown that the antioxidant properties of the carbon fibers with oxide-alumina-silica coating improved significantly. The concentration of precursor sol had an influence on the coating of carbon fibers and the antioxidant properties of the carbon fibers with oxide alumina silica coating increased 300°C compared to uncoated ones.

SiC/SiO2 Coating on Matrix Graphite Spheres of HTR Fuel Element Produced by a Two-Step Pack Cementation/High-Temperature Oxidation Process

2016 ◽  
Vol 852 ◽  
pp. 952-958 ◽  
Author(s):  
Ping Zhou ◽  
Zi Qiang Li ◽  
Hong Sheng Zhao ◽  
Kai Hong Zhang ◽  
Xiao Xue Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Oxidation Process ◽  
Reactor Core ◽  
Isothermal Oxidation ◽  
Pack Cementation ◽  
Temperature Oxidation ◽  
Matrix Graphite ◽  
Fuel Elements

Graphite is one of the most important material for the reactor core and fuel elements of high temperature gas-cooled reactor (HTR). Improving the oxidation resistance of graphite is very essential for the research of new fuel elements and the development of HTR. In this study, a gradient SiC layer of 500~700 μm was prepared on matrix graphite spheres by a two-step pack cementation, and the outer SiO2 layer prepared by the high-temperature oxidation process. The phases, microstructure, bonding strength and oxidation resistance of SiC/SiO2 coated matrix graphite spheres were investigated. The SiC/SiO2 coated matrix graphite spheres were carried on rapid thermal shocking tests from 1773 K to room temperature for 50 times without any cracks. The SiC/SiO2 coated matrix graphite spheres exhibits excellent anti-oxidation properties. No obvious weight loss was found after isothermal oxidation in air at 1273 K for 50 h and the weight gain was less than 1% at 1773 K in air for 50 h due to the oxidation of SiC layer.

Adsorption Characteristics of Modified MiL-101(Cr) for Gas (Mainly CH4) Storage Applications

2015 ◽  
Author(s):  
How Wei Benjamin Teo ◽  
Anutosh Chakraborty ◽  
Kim Tiow Ooi
Keyword(s):  
Natural Gas ◽  
X Ray Diffraction ◽  
Uptake Capacity ◽  
N2 Adsorption ◽  
Thermo Gravimetric ◽  
X Ray ◽  
Thermo Gravimetric Analyzer ◽  
Metal Organic ◽  
Ch4 Uptake

As promising material for gas storage applications, MIL-101(Cr) can further be modified by doping with alkali metal (Li+, Na+, K+) ions. However, the doping concentration should be optimized below 10% to improve the methane adsorption. This article presents (i) the synthesis of MIL-101 (Cr) Metal Organic Frameworks, (ii) the characterization of the proposed doped adsorbent materials by X-ray Diffraction, Scanning Electron Microscopy, N2 Adsorption, Thermo-Gravimetric Analyzer, and (iii) the measurements of methane uptakes for the temperatures ranging from 125 K to 303 K and pressures up to 10 bar. It is found that the Na+ doped MIL-101(Cr) exhibits CH4 uptake capacity of (i) 295 cm3/cm3 at 10 bar and 160 K and (ii) 95 cm3/cm3 at 10 bar at 298 K. This information is important to design adsorbed natural gas (ANG) storage tank under ANG-LNG (liquefied natural gas) coupling conditions.

Immobilization of K7PW11O39 on ZrO2 Nanofiber: Ultra-deep Desulfurization Based in Extraction Catalytic Oxidation Desulfurization System

2021 ◽  
Vol 72 (3) ◽  
pp. 89-101
Author(s):  
Guowei Zeng ◽  
Guihong Wu ◽  
Zhihui Wang ◽  
Xiaonan Li ◽  
Jie Yang ◽  
...  
Keyword(s):  
Catalytic Oxidation ◽  
Catalytic Mechanism ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Thermo Gravimetric ◽  
Transmission Electron ◽  
Deep Desulfurization ◽  
Thermo Gravimetric Analyzer ◽  
Ft Ir ◽  
Model Oil

In this work, K7PW11O39 (abbreviated as PW11) was immobilized on ZrO2 nanofibers and used as an efficient recyclable catalyst in extraction catalytic oxidation desulfurization system (ECODS).The 500 ppm DBT model oil(5mL) can desulphurize completely within 20 min with the catalytic conditions of 50��, 0.010 g 50 wt%- CTAB�C PW11�CZrO2 nanofibers and O/S molar ratio H2O2/DBT molar ratio�� was 2:1. The synthesized catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and thermo gravimetric analyzer (TGA). The results indicated the PW11�CZrO2 nanofibers were synthesized successfully and the possible catalytic mechanism is also revealed.

Effect of Hf Content on Oxidation Resistance of Single Crystal Superalloy at 1000°C

2014 ◽  
Vol 915-916 ◽  
pp. 562-566 ◽  
Author(s):  
Z.X. Shi ◽  
Shi Zhong Liu ◽  
M. Han ◽  
J.R. Li
Keyword(s):  
Grain Size ◽  
Single Crystal ◽  
Oxide Scale ◽  
Oxide Layer ◽  
Oxidation Resistance ◽  
Isothermal Oxidation ◽  
Single Crystal Superalloy ◽  
Ambient Atmosphere ◽  
Directionally Solidified ◽  
Better Than

The specimens of single crystal superalloy DD6 with 0.10% Hf and 0.47% Hf were prepared in the directionally solidified furnace. The effect of Hf content on the isothermal oxidation resistance of the second generation single crystal superalloy DD6 was studied at 1000°Cin ambient atmosphere. Morphology of oxides was examined by SEM, and their composition was analyzed by XRD and EDS. The experimental results show that the oxidation resistance of DD6 alloy with 0.47% Hf is better than that of the alloy with 0.10% Hf. The alloy with different Hf content all obeys parabolic rate law during oxidation for 100h at 1000°C. The increase of Hf content can promote the Al2O3 formation and decreases the proportion of NiO. The oxide grain size and the thickness of the oxide layer all reduce with increasing of Hf content. The oxide scale of the alloy with different Hf content is made up of an outer NiO layer with a small amount of Co3O4, inner Al2O3 and Cr2O3 layer with a small amount of TaO2.

Preparation and Characterization of Silicate Wood Adhesive Modified with Ammonium Stearate

2014 ◽  
Vol 1033-1034 ◽  
pp. 1048-1053 ◽  
Author(s):  
Xin Li Zhang ◽  
Hong Hui Zhang ◽  
Yi Qiang Wu ◽  
Yun Chu Hu
Keyword(s):  
Bonding Strength ◽  
Water Resistance ◽  
Wood Adhesive ◽  
National Standard ◽  
Adhesion Properties ◽  
Good Thermal Stability ◽  
Thermo Gravimetric Analyzer ◽  
Infrared Spectrometer ◽  
Grade Ii

In order to improve the water resistance of silicate wood adhesive, a kind of silicate adhesive was prepared from water glass with silica as curing agent, and ammonium stearate as modifier. The chemical structure, surface morphology and thermal properties of the silicate adhesive were characterized by Fourier transform infrared spectrometer, scanning electron microscope, and thermo-gravimetric analyzer. As the two main measures of adhesion properties, the bonding strength and water resistance were also determined. The results showed that ammonium stearate was successfully introduced into the molecule structure of silicate, the silicate adhesive have good thermal stability in the range of 30~800 °C and the modified silicate adhesive had more smooth cured morphology. The bonding strength and 24h water absorption rate of poplar plywood glued by the silicate adhesive was 0.71 MPa and 22.81%, respectively, reaching the grade II of plywood performance's national standard.

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