Ashless antioxidants, copper deactivators and corrosion inhibitors: Their use in lubricating oils

Hamblin, P. C.; Kristen, U.; Chasan, David E.

doi:10.1002/ls.3010020403

Cited by 32 publications

(13 citation statements)

References 10 publications

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“…It is well documented in literature that benzotriazole is a good corrosion inhibitor for the protection of copper in aqueous environments, so an OBT was chosen for study to see if the same was true in oil‐based media. Dimercaptothiadiazole was chosen as it is a common corrosion inhibitor used in lubricating fluids …”

Section: Methodsmentioning

confidence: 99%

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Automatic transmission fluid corrosion inhibitor interactions with copper

Warren

Hunt²,

Bryant

et al. 2018

Lubrication Science

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In this paper, a new method, measuring the change in resistance of a thin copper wire, has been applied to provide a way to monitor a corrosion reaction in situ. Two different corrosion inhibitors used in commercial automatic transmission fluids have been studied at 110 °C, 120 °C, 130°C, and 150 °C using this new test method coupled with a more traditional coupon test to allow surface analysis to be carried out. Both inhibitors were found to be equally as effective up to temperatures of 130°C; however, the evidence provided shows that at 150°C, the thiadiazole inhibitor is breaking down leading to severe pitting on the surface. Corrosion performance therefore, cannot be assumed to be effective at all temperatures, and the current method provides a convenient quantitative screening method for inhibitor evaluation.

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Section: Methodsmentioning

confidence: 99%

“…Dimercaptothiadiazole was chosen as it is a common corrosion inhibitor used in lubricating fluids. [9][10][11][12][13] Copper coupons of 99.95% purity, provided by Metaspec, USA, were precut into approximately 1-cm lengths. Each test used 1 copper coupon per beaker.…”

Section: Methodsmentioning

confidence: 99%

Automatic transmission fluid corrosion inhibitor interactions with copper

Warren

Hunt²,

Bryant

et al. 2018

Lubrication Science

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“…Although it has been reported that the degradation is caused by an autocatalytic reaction, the degradation mechanism of turbine oil is very complicated [25][26][27]. Air and water combined with localized high temperatures or static electricity are the main causes of oil oxidation and degradation [28].…”

Section: Degradation Mechanismmentioning

confidence: 99%

Composition and degradation of turbine oil sludge

Liu¹,

Wang²,

Zhang

et al. 2016

J Therm Anal Calorim

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Sludge is an inevitable by-product of turbine oil during the operation of lubricating turbines. However, there are few reports of the detailed analytical results of the sludge. In addition, no global specification exists to evaluate the sludge formation from turbine oils. Hence, it is critical to analyze the contents of the sludge. In this study, we investigate both fresh and in-service (contains sludge) turbine oil based on ASTM standards. In-service turbine oil was first washed by petroleum ether to obtain the sludge and then characterized by FTIR, SEM, TG and EDAX. We found that the main compositions of sludge were C, O and N, while metals were \4 mass %. The analytical results show that antioxidant, defoamer, antirust and demulsifier are possible origins for the formation of sludge, which would be beneficial to decrease the sludge for the formulation of turbine oil.

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“…The mechanism of auto-oxidation of hydrocarbon lubricating oils is a well-researched and established subject (Hamblin et al 1989, Mayo 1968. It is generally accepted that it follows the mechanism for low molecular weight saturated hydrocarbons in the liquid phase, i.e., it is a free radical chain mechanism consisting of the following steps:…”

Section: Free Radicalsmentioning

confidence: 99%

“…The mechanisms of initiation and chain propagation (Hamblin et al 1989) for the auto-oxidation of lubricating oils are assumed to be very similar, for both hydrocarbon-based and polyol esterbased lubricating oils: As was mentioned before reaction (7) is stress induced, aided by catalysts and gets the chain reaction started, while (8) is the oxygen absorbing step, which results in the formation and accumulation of the hydro peroxides ROOH (9) and perhaps their accumulation. Reaction (8) is faster than reaction (7).…”

Section: Initiation Chain Propagation Chain Branching Chain Terminationmentioning

confidence: 99%

Using Acid Number as a Leading Indicator of Refrigeration and Air Conditioning System Performance

Cartlidge¹,

Schellhase²

2003

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EXECUTIVE SUMMARYAir conditioning and refrigeration equipment needs to provide long-term reliable use. However, over long periods of time, stress induced deterioration of the refrigerant and/or lubricant will occur which can cause changes in the system chemistry resulting in decreased operating efficiency and potentially can lead to a failure of the system. A number of degradation processes contribute to the deterioration and are reflected by changes in parameters such as acidity, moisture content, viscosity, dissolved metal content, etc., which are all related to the formation of increasing amounts of acids over time. Total acid number (TAN), which includes both mineral acids and organic acids, is therefore a useful indicator which can be used to monitor the condition of the system in order to perform remedial maintenance, when required, to prevent system failure. A literature review was performed to assess the acidity characteristics of the older mineral oil and newer polyolester (POE) refrigeration systems as well as to evaluate acid measuring techniques used in other non-aqueous systems which may be applicable for refrigeration systems.Failure in the older chlorofluorocarbon/hydrochlorofluorocarbon (CFC/HCFC) / mineral oil systems was primarily due to thermal degradation of the refrigerant which resulted in the formation of hydrochloric and hydrofluoric acids. These are strong mineral acids, which can, over time, severely corrode the system metals and lead to the formation of copper plating on iron surfaces. The oil lubricants used in the older systems were relatively stable and were not prone to hydrolytic degradation due to the low solubility of water in oil.The refrigerants in the newer hydrofluorocarbon (HFC)/POE systems are much more thermally stable than the older CFC/HCFC refrigerants and mineral acid formation is negligible. However, acidity is produced in the new systems by hydrolytic decomposition of the POE lubricants with water to produce the parent organic acids and alcohols used to prepare the POE. The individual acids can therefore vary but they are generally C 5 to C 9 carboxylic acids. Organic acids are much weaker and far less corrosive to metals than the mineral acids from the older systems but they can, over long time periods, react with metals to form carboxylic metal salts. The salts tend to accumulate in narrow areas such as capillary tubes, particularly if residual hydrocarbon processing chemicals are present in the system, which can lead to plugging.The rate of acid production from POEs varies on a number of factors including chemical structure, moisture levels, temperature, acid concentration and metals. The hydrolysis rate of reaction can be reduced by using driers to reduce the free water concentration and by using scavenging chemicals which react with the system acids.The critical TAN value is the acid level at which remedial action should be taken to prevent the onset of rapid acid formation which can result in system failure. The level of 0.05 mg KOH/g of oil was established fo...

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Ashless antioxidants, copper deactivators and corrosion inhibitors: Their use in lubricating oils

Cited by 32 publications

References 10 publications

Automatic transmission fluid corrosion inhibitor interactions with copper

Automatic transmission fluid corrosion inhibitor interactions with copper

Composition and degradation of turbine oil sludge

Using Acid Number as a Leading Indicator of Refrigeration and Air Conditioning System Performance

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