Thermal Oxidative Stability of Vegetable Oils as Metal Heat Treatment Quenchants

Abstract

The potential use of vegetable oil derived industrial oils continues to be of great interest because vegetable oils are relatively non-toxic, biodegradable, and a sustainably produced basestock alternative to petroleum oil, a non-renewable basestock. For the conservation of the environment, bio-mass materials, such as vegetable oils, are desirable as substitutes for petroleum oil in heat treatment. Therefore, it is expected that these basestock materials will continue to be of increasing interest in the heat treatment industry. However, the fatty ester components containing conjugated double bonds of the triglyceride structure of vegetable oils typically produce considerably poorer thermal oxidative stability than that achievable with petroleum basestocks under typical use conditions. This is especially true when a vegetable oil is held in an open tank with agitation and exposure to air at elevated temperatures for extended periods of time (months or years). Furthermore, when used as quenchants, furnace loads of hot steel (850 °C) are typically rapidly immersed and cooled to approximately 50 °C to 60 °C bath temperatures for steel hardening applications. Clearly, for this application, reasonable thermal-oxidative stability is essential. This paper reviews the work completed thus far in screening various vegetable oils as potential steel quenchants both with and without antioxidants. Particular focus is placed, where possible, on comparing pressure differential scanning calorimetry as a potential screening method with the more commonly used (for this application) modified Indiana Stirring Oxidation Test. In addition, the general impact of oxidation on the quenching performance of the better vegetable oil candidates is shown.

Synthesis of Biolubricant Trimethylolpropane Trioleate and Its Lubricant Base Oil Properties

“…Besides, OA is economical and easier to store than linoleic and linolenic acids; therefore, OA has better development value. 10 Trimethylolpropane trioleate (TMPTO) is a chemically modified product of triglyceride. In comparison to vegetable oil, it has better oxidative stability and better low-temperature properties and could be used as a green lubricant.…”

“…A previous study has documented that the oxidative stability potential of vegetable oils could be improved with the increase of the oleic acid (OA) component and the decrease of both the linolenic and linoleic acid components. Besides, OA is economical and easier to store than linoleic and linolenic acids; therefore, OA has better development value …”

Heat Transfer Characteristics and Cooling Performance of Treated Kitchen Coconut Oil

“…The only drawback with vegetable oils is that they have inferior thermal and oxidative stabilities. Vegetable oils degrade faster than mineral oil and hence, have limited application as a quench medium [3][4][5].…”

“…Investigations have been carried out on various edible oils such as canola oil, coconut oil, cottonseed oil, groundnut oil, olive oil, palm oil, rapeseed oil, soybean oil, sunflower oil, etc. However, consumption of edible oils for industrial purposes may affect the food chain supply [5][6][7][8][9]. In this present work, the waste coconut cooking oil is used as an alternative quench medium for industrial heat treatment by subjecting it to chemical treatment.…”

Assessment of Cooling and Heat Transfer Properties of Quenchants with MATLAB

“…Recently, Carvalho et al [5,6]; Belinato, Canale, and Totten [7]; and others have similarly examined the quenching behavior of vegetable oils using cooling time and rates. These cooling curve data parameters were also compared to typical petroleum oil quenchants, and the results similarly indicated very short, if observable, film-boiling regions for vegetable oils in general when compared to petroleum oil quenchants.…”