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Article
Publication date: 19 July 2019

Bingxue Cheng, Haitao Duan, Yongliang Jin, Lei Wei, Jia Dan, Song Chen and Jian Li

This paper aims to investigate the thermal oxidation characteristics of the unsaturated bonds (C=C) of trimethylolpropane trioleate (TMPTO) and to reveal the high…

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Abstract

Purpose

This paper aims to investigate the thermal oxidation characteristics of the unsaturated bonds (C=C) of trimethylolpropane trioleate (TMPTO) and to reveal the high temperature oxidation decay mechanism of unsaturated esters and the nature of the anti-oxidation properties of the additives.

Design/methodology/approach

Using a DXR laser microscopic Raman spectrometer and Linkam FTIR600 temperature control platform, the isothermal oxidation experiments of TMPTO with or without 1.0 wt. % of different antioxidants were performed.

Findings

The results indicated that the Raman peaks of =C-H, C=C and -CH2- weaken gradually with prolonged oxidation time, and the corresponding Raman intensities drop rapidly at higher temperatures. The aromatic amine antioxidant can decrease the attenuation of peak intensity, as it significantly reduces the rate constant of C=C thermal oxidation. The hindered phenolic antioxidant has a protective effect during the early stages of oxidation (induction period), but it may accelerate the oxidation of C=C afterwards.

Originality/value

Research on the structure changes of synthetic esters during oxidation by Raman spectroscopy will be of great importance in promoting the use of Raman spectroscopy to analyze the oxidation of lubricants.

Details

Industrial Lubrication and Tribology, vol. 71 no. 5
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 January 1971

N.R. Chapman

DISCUSSION The chromium coating thicknesses used in this work were comparable to those used commercially, being between 70 and 170 micrometres approximately. Even after…

Abstract

DISCUSSION The chromium coating thicknesses used in this work were comparable to those used commercially, being between 70 and 170 micrometres approximately. Even after oxidation for the temperatures and times stated the chromium concentrations at the metal‐oxide interface were between 20% and 60%. These concentrations fell steadily to approximately 13% over the approximate depth stated above before reducing sharply to zero at what was the ferrite‐austenite transformation boundary during the coating process. This is contrary to the structure observed in aluminized stainless steels where a complex structure is produced due to the existence of intermetallic phases. Hence during all the oxidation experiments performed the chromium level of the surface offered for oxidation was never below 13% and complete oxidative breakdown therefore did not occur, excluding spalling effects. Many workers have shown that the oxidation rate of iron‐chromium alloys initially drops sharply with increasing chromium but eventually reaches a minimum of about 20% chromium and then rises for more chromium rich alloys. From the graph of oxidation rate in pure oxygen against chromium content given by Mortimer et al., from 13% chromium to 100% chromium the oxidation rate increases by approximately 6 × 10−9 g.cm−2 sec.−1 It is reasonable to assume that for a diffusion coating the oxidation behaviour will be markedly affected by the composition at its outer surface layer and much less by the composition gradient. If oxidation was continued for sufficiently long periods the latter could affect the general availability of chromium ions for the oxidation process. Over the first 5?m the average chromium levels were between 63% and 20% for the chromised and chrome‐aluminized respectively. From the figures given by Mortimer et al the oxidation rate of the 63% chromium coating would be expected to be 0.5 × 10−9 g.cm−2 sec−1 greater than the 20% chromium coating on the chrome‐aluminized specimens at 600°C, on the basis of the chromium content alone. The results obtained here vary in this manner, hence it is reasonable to conclude that the general oxidation behaviour of the coatings will be very similar to that of pure iron‐chromium alloys containing the same chromium content as in the outer few micrometres of the respective coatings. Even though the true surface area is greater with diffusion treated specimens their oxidation rates are lower that for the corresponding pure alloys.

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Anti-Corrosion Methods and Materials, vol. 18 no. 1
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 July 2020

Chunmei Ma, Songting Yang, Yuheng Zhang, Kaikun Wang and Huadong Fu

Due to the special service environment of superalloys, this paper aims to obtain effects of temperature and Ti addition on high temperature oxidation behavior of Co-Al-W-B alloys.

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Abstract

Purpose

Due to the special service environment of superalloys, this paper aims to obtain effects of temperature and Ti addition on high temperature oxidation behavior of Co-Al-W-B alloys.

Design/methodology/approach

Isothermal oxidation experiment of Co-Al-W-based alloys were carried out at 800°C, 900°C and 1000°C for different times (3, 5, 10, 20, 50 and 100 h) referring to the method of HB5258-2000. Oxidation weight gain curves and oxidation products were detected.

Findings

The results showed that the average oxidation rates of Co-Al-W-B alloy at 800 °C and 900 °C were 0.489 g·m−2·h−1 and 0.888 g·m−2·h−1, respectively, which belonged to an antioxidant grade. However, the average oxidation rate at 1000 °C was 2.068 g m−2·h−1, belonging to the secondary oxidation resistance class. In the alloy with Ti addition, dense Ti oxides film were formed at the early oxidation stage and then gradually diffused later, which can increase the oxidation resistance of the alloys to some extent. By analyzing the oxidation products of Co-Al-W-B alloy, it was found that a dense Al2O3 layer could be formed when the alloy was oxidized at 800°C. The continuous Al2O3 layer would prevent the oxygen from further spreading and make the alloy into the stable oxidation stage. However, only a non-dense Al2O3 layer were observed with 900°C oxidation.

Originality/value

It can provide references for the composition design, preparation process optimization and protective coating selection of the γ′ phase strengthened cobalt-base superalloys.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 5
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 10 August 2020

Wen Zhan, Shengpeng Zhan, HaiTao Duan, Xinxiang Li, Jian Li, Bingxue Cheng and Chengqing Yuan

This paper aims to study the thermal oxidation performance of antioxidant additives in ester base oils deeply.

Abstract

Purpose

This paper aims to study the thermal oxidation performance of antioxidant additives in ester base oils deeply.

Design/methodology/approach

ReaxFF molecular dynamics was used to simulate the thermal oxidation process of butyl octyl diphenylamine and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propanoate as two antioxidant additives act on the Trimethylolpropane trioleate (TMPTO) base oil. Meanwhile, combining with the infrared spectroscopy characterization results of the thermal oxidation test, this paper provides theoretical support for the development of high-performance synthetic lubricants and their antioxidant additives.

Findings

The results show that butyl octyldiphenylamine easily removes the hydrogen atom on the secondary amine, which promotes the formation of more long carbon chain diene radicals or polyene hydroperoxides from TMPTO. Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propanoate could easily decompose into octadecyl hydroperoxide and 2,6-di-tert-butyl 4-propionylphenol, which could convert into 2-tert-butyl-4-peroxyethyl-6-hydroperoxy-tert-butylphenol in the middle of the thermal oxidation reaction, prompting TMPTO to form more short-chain alkenyl and olefin hydroperoxide or other oxide.

Originality/value

The main change characteristics of base oil molecules are the first thermal decomposition to form oleic acid groups and ethane cyclopropane methyl oleate. Under the action of butyl octyldiphenylamine and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propanoate, the deep oxidation and decomposition reaction are slowed down.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0037/

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Article
Publication date: 19 May 2020

Jialin Yang, Yunting Guo, Wei Zai, Siyuan Ma, Liang Dong and Guangyu Li

This paper aims to find a way to improve the surface insulation, corrosion resistance and mechanical properties of Fe-Cr-Al electrothermal alloy, exploring the best…

Abstract

Purpose

This paper aims to find a way to improve the surface insulation, corrosion resistance and mechanical properties of Fe-Cr-Al electrothermal alloy, exploring the best oxidation condition and analyzing the oxidation mechanism.

Design/methodology/approach

Electrochemical workstation was used for anodic oxidation, and the effect of current density, ethylene glycol concentration and oxidation time on properties of the film were investigated by resistivity test, scanning electron microscope, electrochemical tests (potentiodynamic polarization and electrochemical impedance spectroscopy) and mechanical tests, and the oxidation process was analyzed by X-ray photoelectron spectroscopy (XPS).

Findings

According to the potential-time curves of anodic oxidation and the analysis of XPS, the whole oxidation process can be divided into four stages. When the current density is 0.8 A/dm2, the ethylene glycol concentration is 10%, and the oxidation time is 60 min, the film has the best corrosion protection, mechanical properties and surface morphology. The resistivity of the samples is about 13 orders magnitude than that of the matrix.

Originality/value

In this paper, a protective electrically insulating film was prepared by anodic oxidation in an alkaline electrolyte solution. The oxidation conditions were optimized and the oxidation mechanism was analyzed.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 4
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 26 August 2020

Zhaowei Su, Rui Mu, Yonghui Cui, Hongda Zhu, Xuetian Li and Zhongcai Shao

The purpose of this paper is to prepare composite micro-arc oxide coatings with better wear resistance and corrosion resistance.

Abstract

Purpose

The purpose of this paper is to prepare composite micro-arc oxide coatings with better wear resistance and corrosion resistance.

Design/methodology/approach

A nickel powder composite micro-arc oxide film was prepared on the surface of the magnesium alloy by the method of organically combining ultra-fine Ni powder with micro arc oxidation film layer. In this experiment, the changes in the corrosion resistance and microstructure of the composite film layer after adding Ni powder were studied, and the effect of the addition of glycerin on the corrosion resistance of the film layer was analyzed.

Findings

The results show that the ultra-fine nickel powder was successfully prepared by the liquid phase reduction method, and the micro-arc oxidation process was modified under the optimal addition amount. The surface of the micro-arc oxide film made of ultra-fine nickel powder was found by SEM to have smooth surfaces and few holes. According to X-ray diffraction analysis, the phase composition of the micro-arc oxide film layer was Mg, Ni, NiSiO4, MgNi (SiO4) and Mg2SiO4. According to the results of electrochemical tests, the corrosion resistance of the micro-arc oxidation composite film layer was improved after the addition of ultra-fine Ni powder, the corrosion current was greatly reduced and the impedance has been improved. And after adding glycerin, the surface of the film layer becomes denser, and the corrosion resistance of the micro-arc oxide film is significantly improved.

Originality/value

Through this experimental research, a micro-arc oxide coating of powder composite magnesium alloy was successfully prepared. The corrosion resistance of the micro-arc oxidation film layer has been improved, and certain functions had been given to the micro-arc oxidation composite film, which has increased the application field of magnesium alloys.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 5
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 September 2006

H. Singh, D. Puri, S. Prakash and M. Srinivas

To characterise the high temperature oxide scales for some plasma sprayed NiCrAlY coated Ni‐ and Fe‐based superalloys.

Abstract

Purpose

To characterise the high temperature oxide scales for some plasma sprayed NiCrAlY coated Ni‐ and Fe‐based superalloys.

Design/methodology/approach

Ni‐22Cr‐10Al‐1Y metallic coatings were deposited on two Ni‐based superalloys; Superni 601 and Superni 718 and one Fe‐based superalloy; Superfer 800H by the shrouded plasma spray process. Oxidation studies were conducted on uncoated as well as plasma spray coated superalloys in air at 900°C under cyclic conditions for 50 cycles. Each cycle consisted of 1 h heating followed by 20 min of cooling in air. The thermogravimetric technique was used to approximate the kinetics of oxidation. X‐ray diffraction, SEM/EDAX and EPMA techniques were used to analyse the oxide scales.

Findings

All of the coated, as well as the uncoated, superalloys followed an alnost‐parabolic rate of oxidation. The NiCrAlY coating was found to be successful in maintaining its continuous contact with the superalloy substrates in all the cases. The oxide scales formed on the exposed NiCrAlY coated superalloys were found to be intact and spallation‐free. The main phases analysed for the coated superalloys were oxides of nickel, chromium and aluminium and spinel of nickel and chromium, which are expected to be useful for developing oxidation resistance at high temperatures.

Practical implications

The coated superalloys showed remarkable cyclic oxidation resistance under simulated laboratory conditions. However, it is suggested that these coated superalloys also should be tested in actual industrial environments of boilers and gas turbines, etc. so as to obtain more practical and reliable oxidation data.

Originality/value

The knowledge of the reaction kinetics and the nature of the surface oxide scales formed during oxidation is important for evaluating the alloys for their use and degradation characteristics in high temperature applications such as steam boilers, furnace equipment, heat exchangers and piping in chemical industry, reformer, baffle plates/tubes in fertilizer plants, jet engines, pump bodies and parts.

Details

Anti-Corrosion Methods and Materials, vol. 53 no. 5
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 27 September 2018

Fupeng Cheng, Jinglong Cui, Shuai Xu, Song Li, Pengchao Zhang and Juncai Sun

The purpose of this study is to improve the performance of AISI 430 stainless steel (430 SS) in increasing its oxidation resistance, suppressing coating spalling and…

Abstract

Purpose

The purpose of this study is to improve the performance of AISI 430 stainless steel (430 SS) in increasing its oxidation resistance, suppressing coating spalling and cracking, sustaining appropriate conductivity and blocking Cr evaporation as an interconnect material for intermediate temperature solid oxide fuel cells; a protective co-contained coating is formed onto stainless steel via the surface alloying process and followed by thermal oxidation.

Design/methodology/approach

In this work, oxidation behavior of coated specimen is studied during isothermal and cyclic oxidation measurements. Moreover, the conductivity is also investigated by area specific resistance (ASR) measurement.

Findings

Co-contained spinel layer shows an outstanding performance in preventing oxidation and improving conductivity compared with uncoated specimens. The protective spinel coating also reduces the ASR for coated specimen (0.0576O cm2) as compared to the uncoated specimen (1.87296O cm2) after isothermal oxidation.

Originality/value

The probable mechanism of co-contained alloy converting into spinel and the spinel transfer electron is presented.

Details

Anti-Corrosion Methods and Materials, vol. 65 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 14 June 2018

Omar Alejandro Valdés-Saucedo, Liliana Judith Vázquez-Rodríguez, Brenda López-Zárate, Lorena Garza-Tovar, Nora Aleyda García-Gómez, Alfredo Artigas, Alberto Monsalve, Javier H. Humberto Ramírez-Ramírez, Francisco Aurelio Pérez-González, Rafael Colás and Nelson Federico Garza-Montes-de-Oca

This paper aims to analyse the surface evolution of pure recycled titanium subjected to isothermal and cyclic oxidation conditions using dry air as oxidant gas. It is…

Abstract

Purpose

This paper aims to analyse the surface evolution of pure recycled titanium subjected to isothermal and cyclic oxidation conditions using dry air as oxidant gas. It is important to mention that the cyclic oxidation behaviour of pure titanium is a process that has been barely studied.

Design/methodology/approach

An isothermal and cyclic oxidation reactor was built for these purposes. This installation allows the oxidation of material under the action of any atmosphere and for temperatures up to 1,200°C. For this study, the oxidation behaviour of the material was studied at 850°C and 950°C.

Findings

Oxide growth under isothermal oxidation conditions in air follows a parabolic behaviour with an activation energy of 118 kJ/mol, and the oxide phase formed on the surface of the metal was rutile. The cyclic oxidation of the material indicates that oxide is spalled from the surface following linear behaviours; this phenomenon is controlled by the thermal stresses experienced by the samples during heating and cooling cycles.

Originality/value

The material is obtained from the production of electrolytic copper, and during its reprocessing practices at high temperature, it was thought that it could experience some abnormal oxidation. In addition, given that pure titanium is currently used for biomedical application, some surface degree can be given by means of oxidation and subsequent spallation process situation that is found during the cyclic oxidation experiments, which could be a low-cost method to engineer a surface for these purposes.

Details

Anti-Corrosion Methods and Materials, vol. 65 no. 4
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 8 April 2014

Gaiqing Zhao, Qin Zhao, Xiaobo Wang and Weimin Liu

The purpose of this paper is to study a novel Mannich adduct of benztriazole-containing diphenylamine (coded as BD) and its anti-oxidation properties as an additive in two…

Abstract

Purpose

The purpose of this paper is to study a novel Mannich adduct of benztriazole-containing diphenylamine (coded as BD) and its anti-oxidation properties as an additive in two typical synthetic ester-based oils.

Design/methodology/approach

The anti-oxidation properties in two typical synthetic ester-based oils were evaluated in detail, using rotating pressure vessel oxidation test. The tribological properties of BD in synthetic ester-based oil (A51) were also tested with Optimal SRV-I oscillating friction and wear tester at atmosphere.

Findings

The results of tests demonstrated that the novel BD compound is, indeed, a high-performance anti-oxidation additive that was able to remarkably improve the oxidation stability of synthetic ester-based oils, when it was added at only 0.5 per cent concentration and compared with the base oils containing 0.5 per cent of the commercial available antioxidant additives such as 2, 6-di-tert-butyl-4-methylphenol and octyl-butyl diphenylamine. A plausible mechanism of exceptional synergistic anti-oxidation was proposed.

Originality/value

This paper first investigated the anti-oxidation properties and mechanisms of the compound with the structure of BD, which can be very useful and would promote the application of BD antioxidant in the lubricant industry.

Details

Industrial Lubrication and Tribology, vol. 66 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

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