Oxidation Behaviors of DO3 Type Fe3Si Based Intermetallics at 900°C

2010 ◽  
Vol 146-147 ◽  
pp. 1904-1910
Author(s):  
Qi Zhou ◽  
Jian Gang Jia ◽  
Hong Shun Zhao ◽  
Xin Min Zhang
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Product ◽  
Oxidation Reaction ◽  
Protective Oxide ◽  
Kinetics Of Oxidation ◽  
Good Oxidation Resistance ◽  
Arc Melting ◽  
Protective Oxide Film ◽  
Kinetics Of ◽  
Oxidation Behaviors

In the present work, intermetallics Fe3Si and Fe3 (Si1-xAlx) (x=0.33, 0.67, 0.80) produced by arc melting, were evaluated regarding the oxidation at 900°C in air. The test preformed was the isothermal and cyclic oxidation. The microstructures of oxide films were analyzed by XRD, SEM, EDS, EPMA. The result showed that the four kinds of intermetallics had good oxidation resistance at 900°C.The addition of Al element can increase the oxidation resistance of Fe3Si based intermetallics. The oxidation kinetics of the four intermetallics follows the rule of the parabola. The main oxidation product of Fe3Si is SiO2.The kinetics of oxidation reaction is mainly controlled by Si diffusion. The oxidation product of three Al alloying Fe3Si based intermetallics is Al oxide. Al moves outward from the substrate to form a protective oxide film which restrained the diffusion of Si and Fe outward.

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.

The Role of H2O2 and K2S2O8 as Oxidizing Agents for Accelerated Corrosion Testing

CORROSION ◽  
10.5006/3443 ◽  
2020 ◽  
Vol 76 (4) ◽  
pp. 373-384
Author(s):  
Mary E. Parker ◽  
Russell Repasky ◽  
Srishti Shrivastava ◽  
Robert G. Kelly
Keyword(s):  
Immersion Test ◽  
Corrosion Testing ◽  
Solution Ph ◽  
Protective Oxide ◽  
Accelerated Corrosion ◽  
Oxidizing Agents ◽  
Accelerated Corrosion Testing ◽  
Protective Oxide Film ◽  
Kinetics Of

In this work, the application of hydrogen peroxide (H2O2) and potassium persulfate (K2S2O8) in accelerated corrosion testing was considered. H2O2 is already used as an accelerant in the standard immersion test ASTM G110, and K2S2O8 is an oxidizing agent that shows promise for corrosion testing applications. A Koutecky-Levich approach was used to investigate the cathodic kinetics of both oxidizing agents as well as dissolved oxygen (O2). Cathodic kinetics for O2, H2O2, and S2O82− were faster when measured on a platinum electrode than when measured on an AA2060-T3 electrode. This difference was attributed to the additional limit to cathodic kinetics posed by the protective oxide film on aluminum. H2O2 was a more potent accelerant than K2S2O8 at a concentration of 0.1 M due to the faster cathodic kinetics of H2O2 on aluminum. However, K2S2O8 was more convenient to use in a laboratory setting due to its stability during storage. The severity of tests using K2S2O8 was increased by lowering the solution pH to 2.28. At the low solution pH, cathodic kinetics and extent of attack increased.

scholarly journals The Kinetics of Oxidation Reaction of Chromite by NaOH-NaNO3 Molten Salts

1974 ◽  
pp. 54-59 ◽  
Author(s):  
Kohji KASHIWASE ◽  
Gen-ichi SATO ◽  
Ei-ichi NARITA ◽  
Taijiro OKABE
Keyword(s):  
Molten Salts ◽  
Oxidation Reaction ◽  
Kinetics Of Oxidation ◽  
Kinetics Of

Assessment of Corrosion Behavior in Artificial Saliva of Wires for Orthodontic Applications

2018 ◽  
Vol 917 ◽  
pp. 197-201
Author(s):  
Aphinan Phukaoluan ◽  
Anak Khantachawana ◽  
Pongpan Kaewtatip ◽  
Surachai Dechkunakorn
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Artificial Saliva ◽  
Open Circuit ◽  
Vacuum Arc ◽  
Orthodontic Wires ◽  
Protective Oxide ◽  
Arc Melting ◽  
Protective Oxide Film ◽  
Significant Difference

The aim of this study, the corrosion behavior of TiNiCu in artificial saliva (pH5.35) at 37°C was assessed by the use of electrochemical methods. Ti50Ni43Cu7 (at%) used in this study were made from ingots prepared by the vacuum arc melting (VAM) method. The furnace was purged with argon gas during melting. All melted ingots were then homogenized at 800°C for 3.6 ks. Open circuit potential (OCP) was monitored at 3.6 ks followed by potentiodynamic techniques. The results showed that all chemical composition of orthodontic wires by EPMA were Ti, Ni, Cu, Cr, Fe and Mn. Surface roughness was measured in order to ensure that TiNiCu and SS was significant difference which might affect corrosion resistance. It was seen that TiNiCu orthodontic wires, presented a good corrosion resistance, compared to the stainless steel, probably due to the formation of a protective oxide film mainly constituted by titanium oxide.

scholarly journals Kinetics and Mechanism of Oxidation ofL-Cystine by Hexacyanoferrate(III) in Alkaline Medium

2009 ◽  
Vol 6 (1) ◽  
pp. 93-98 ◽  
Author(s):  
Annapurna Nowduri ◽  
Kalyan Kumar Adari ◽  
Nageswara Rao Gollapalli ◽  
Vani Parvataneni
Keyword(s):  
Alkaline Medium ◽  
Oxidation Product ◽  
Experimental Results ◽  
Cysteic Acid ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Order Dependence ◽  
Plausible Mechanism ◽  
Mechanism Of Oxidation ◽  
Kinetics Of

Kinetics of oxidation ofL-cystine by hexacyanoferrate(III) was studied in alkaline medium at 30 °C. The reaction was followed spectrophotometrically at λmax = 420 nm. The reaction was found to be first order dependence each on [HCF(III)] and [cystine]. It was found that the rate of the reaction increases with increase in [OH-]. The oxidation product of the reaction was found to be cysteic acid. A plausible mechanism has been proposed to account for the experimental results.

scholarly journals Microstructures and Oxidation Behaviors of Silicide Coated Nb Alloys by Halide Activated Pack Cementation Process

2020 ◽  
Vol 58 (8) ◽  
pp. 507-514
Author(s):  
Wonchul Yang ◽  
Choong-Heui Chung ◽  
Sangyeob Lee ◽  
Kyeong Ho Baek ◽  
Youngmoo Kim ◽  
...  
Keyword(s):  
Oxidation Resistance ◽  
Coating Layer ◽  
Pack Cementation ◽  
Powder Mixtures ◽  
Arc Melting ◽  
Static Oxidation ◽  
Coating Layers ◽  
Pack Cementation Process ◽  
Coating Layer Thickness ◽  
Oxidation Behaviors

In this study, we tried to improve the oxidation resistance of Nb-12Si (wt%) alloys at 1200 °C or higher through pack cementation coatings. Nb-12Si (wt%) alloys were prepared by arc-melting under Ar atmosphere. When the alloys were coated using pack powder mixtures composed of Si, Al2O3 and NaF, two silicide layers composed of NbSi2 and Nb5Si3 phases were successfully produced on the substrate. The Si-pack coatings were performed with various heat treatment temperatures and time conditions. The microstructures and thickness changes of the coating layers were analyzed to determine the growth behaviors of the coating layer. The growth constant of 8.4 10–9 cm2/sec was obtained with a diffusion growth mode. In addition, in order to examine the resistance of the Si-pack coated alloys, isothermal static oxidation tests were performed at 1200 °C and higher temperatures. As a result, the oxidation resistance of the alloys was determined by protecting the surface of the alloys with silicide oxide layers formed by the silicide coatings. The uncoated specimens exhibited an abnormal weight increase due to the formation of Nb oxide. The coated specimen showed excellent oxidation resistance at 1200 °C for up to 12 hrs, while the previous reports on the same alloy verified oxidation resistance only up to 1100 °C. It appears that the excellent oxidation resistance is closely related to the NbSi2 coating layer thickness. The oxidation behaviors of the coating layers after the oxidation tests were discussed in terms of microstructural and phase analyses.

High Temperature Cyclic Oxidation of Coatings on Ni-Based Superalloys

2015 ◽  
Vol 226 ◽  
pp. 137-142
Author(s):  
Marta Kianicová ◽  
Jaroslav Trník
Keyword(s):  
Oxidation Resistance ◽  
Cyclic Oxidation ◽  
Oxidation Products ◽  
Thermo Gravimetric ◽  
Good Oxidation Resistance ◽  
Heating And Cooling ◽  
University Of Technology ◽  
Al Coating ◽  
Kinetics Of ◽  
Cylindrical Samples

The cyclic oxidation behavior of diffusion protective Al and SiAl coatings used on Ni-superalloy namely MAR-M247 at 1100°C for 38 cycles in the air under cyclic heating and cooling conditions has been investigated in the present work. Cyclic oxidation test was carried out in laboratories of Silesian University of Technology in Katowice, Poland. Cylindrical samples were casted from mentioned alloy in factory PBS Velká Bíteš, a.s., Czech Republic. The oxidation kinetics of coated and uncoated superalloys was analyzed by thermo-gravimetric technique. It was observed that all the coated and bare superalloys obey a parabolic rate law of oxidation. SEM/EDX techniques were used to analyses the oxidation products of all samples. MAR-M247 with Al coating showed good oxidation resistance due to the formation of a compact and adhesive thin Al2O3 scale on the surface of the coating during oxidation. SiAl coating showed equally good oxidation resistance. The oxidation progress of uncoated alloy MAR-M247 was very fast.

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