Evaluation of lubricants

The next chapter is a review of current practice in lubrication of internal combustion engines and lubricant design. The role of individual lubricant components and their use in mineral and synthetic formulations is covered. This is followed by a discussion of the tribochemical effects of additive interactions. The heart of the manuscript is chapters, "Tribochemical nature of antiwear film , "Surface tribochemistry and activated processes", and "Analytical techniques in lubricating practices". Topics covered include tribofilm formation, organomolybdenum compounds in surface protection, catalytic activity of rubbing surfaces, introduction of some techniques for evaluation of tribofilms composition and analytical techniques for evaluation of lubricant degradation. Examples of the application of basic concepts are introduced, eg., acidity and basicity in the process of lubricant deterioration. 

Materials commonly used as lubricants are listed in Table 5.2. An evaluation of lubricants in various applications has been given in Table 2.4 along with information on a number of binders used in tableting. 

Another important use of ejection force transducer is the evaluation of lubricants (either different chemically, or similar lubricants coming from different vendors). 

Suren G. Evaluation of lubricants in the development of tablet formula. Dansk Tidsskr Farm 1971 45 331-338. 

The Japanese produced FT product at the Miike Synthetic Oil Company located in Omuta and were in the process of constructing an adjoining a lubricating oil facihty that was not completed before the end of the war. Laboratory evaluation of lubricants prepared from FT oils were performed in the laboratory. Although the U. S. Naval Technical Mission Reports provide data derived from these evaluations, the data are sparse and obviously incomplete likely due to the fact that the technical files of the Japanese Research Institute were destroyed in August 1945. The available data show that for the FT derived lubricating oils the best antioxidant was a combination of triphenylphosphite and chromium oleate. 

G.W. Roper, J.C. Bell, Review and evaluation of lubricated wear in simulated valve train contact conditions (SAE 952473), in Recent Snapshots and Insights into Lubricant Tribology SP-1116, Society of Automotive Engineers, Warrendale, PA, 1995, pp. 67-83. 

Foord, C.A. Hamman, W.C. and Cameron, A. "Evaluation of Lubricants Using Optical Elastohydrodynaralcs" ASLE Trans 1968 11 p... 

MURAKAMI, T., OHTSUKI, N. and MATSUI, H. The evaluation of lubricating film formation in knee prostheses in a knee joint simulator, Trans. JSME, (to be published in Japanese). 

Wood, J.C., Surette, B.A., Aitchison, I., Clendening, W.R., 1980. Pellet cladding interaction evaluation of lubrication by graphite. Journal of Nuclear Materials 88 (1), 81—94. 

A method of evaluation of lubricating-oil stocks involving precipitation of asphaltenes with petroleum ether, a fuller s earth petroleum ether fractionation to isolate resins, dewaxing with methyl ethyl ketone and benzene to separate wax, and an adsorption fractionation to provide cuts for determining the Viscosity Index-yield relationship has been developed by N. W. Furby. The results of such a study have been successfully correlated with plant performance. 

Although distillation and elemental analysis of the fractions provide a good evaluation of the qualities of a crude oil, they are nevertheless insufficient. Indeed, the numerous uses of petroleum demand a detailed molecular analysis. This is true for all distillation fractions, certain crude oils being valued essentially for their light fractions used in motor fuels, others because they make quality lubricating oils and still others because they make excellent base stocks for paving asphalt. 

Much confusion exists as to the best choice of lubricant additives for a given situation. Evaluation both in the laboratory and in the field is difficult because of the dynamic nature of the drilling fluid and the wide range of factors that influence drill string torque and drag. Liquid lubricants are used at concentrations of 0.25—4 vol %, soHd materials at ca 6—29 kg/m (2—10 Ib/bbl). 

Operating experience has proven that unless a continuous program of required lubrication is followed, even the most well-designed units are sure to fail. A proper lubrication management program must incorporate a monthly lubrication schedule, an evaluation of new lubrication products, and supervision to ensure the prescribed procedures are carried out by maintenance personnel. 

The performance characteristics of a lubricating oil depend on its origin and on the refining processes employed, and in order to ensure consistent properties these are varied as little as possible. Some aero-engine builders insist on a complete re-evaluation of a lubricant, costing many thousands of pounds, whenever there is a change of source (crude) or refining process. 

Most hydraulic fluid preparations start as chemical mixtures. For instance, there is a considerable area of overlap in the specific petroleum hydrocarbon chemicals contained in the mineral oil and polyalphaolefin hydraulic fluids. For all classes of hydraulic fluids, there may be similarities with other original products intended for use as lubricants. The complications involved in documenting the environmental fate of mixtures increase under conditions encountered at many NPL sites, where it may be hard to determine the precise original product associated with chemicals identified at an area in need of remediation. In most instances, available peer-reviewed literature, supplemented with data obtained from manufacturers of particular formulations and information in trade magazines, can supply information about the original hydraulic fluid preparations. At NPL sites, site-specific evaluations of specific chemicals may be the only feasible way to address concerns over environmental fate and potential exposure risks. 

It was recognized quite some time ago that DTA analysis could be used to deduce the compatibility between a drug substance and its excipients in a formulation. The effect of lubricants on performance was as problematic then as it is now, and DTA proved to be a powerful method in the evaluation of possible incompatibilities. Jacobson and Reier used DTA to study the interaction between various penicillins and stearic acid [17]. For instance, the addition of 5% stearic acid to sodium oxacillin monohydrate completely obliterated the thermal events associated with the antibiotic. Since that time, many workers employed DTA analysis in the study of drug-excipient interactions, although the DTA method has been largely replaced by differential scanning calorimetry technology. 

A.S. El-Hagrasy, S-Y. Chang and S. Kiang, Evaluation of risk and benefit in the implementation of near-infrared spectroscopy for monitoring of lubricant mixing, Pharm. Dev. Technol, 11, 303-312 (2006). 

One example of the effect of such factors is UV inks used in printing, which were the snbject of a scandal early on, the positive evaluation of aqueous systems and bio paints , which were evaluated veiy positively despite their not unproblematic content of vegetable-based solvents. In addition, the comparatively speedy snbstitntion of chlorinated solvents in cleaning processes and formaldehyde separators in cooling lubricants can only in fact be explained by the pubhc-ity-effective scandals relating to chlorinated chemicals or formaldehyde. 

Analytical techniques to evaluate potential lubricating oil stocks are essential to a refiner s planning program. When sulfuric acid was the sole chemical used to refine burning oils and lubricants, it was a simple matter to carry out acid-treating experiments on a small scale in the laboratory, and results so obtained were quite reliable. With the advent of solvent treating, analytical techniques were developed which consisted of single or multiple-batch laboratory extractions in conjunction with correlations based on plant experience (17). 

The only real test to determine that the scale-up batch will run well on the selected tablet press in production is a use test i.e., the batch must be run. Although there is no completely accurate prediction of compaction behavior during scale-up, there are many excellent test methods that can provide an evaluation of specific material properties (flow, lubrication, etc.) and provide an understanding of the material properties of one s formulation. If proper science is applied, these measurements and approaches can provide assurance that scale-up can occur with a minimum of problems. 

Table 2.7. Performance of synthetic and mineral lubricant oils. Relative evaluation of viscosity, stability (thermal, oxidation, hydrolytic, volatility), lubricity (wear protection and fatigue) and environmental impact...

The abrasivity of surfaces is related to the shape of surface profiles and can be described numerically. The morphology of wear particles, in terms of their shape, size, and surface texture, reflects the complex nature of the wear process involved in particle formation (Stachowiak, 1998 and 2000 Stachowiak and Podsiadlo, 1999 and 2001). The cumulative evaluation of turbine lubricating oil system, using techniques such as automatic particle counters, ferrography, ICP-AES spectroscopy, and scanning electron microscopy indicated the involvement of very small iron particles in the size range of 1-10 microns or less, and abrasive wear silica particles in the size range of 10-40 microns (Korycki and Wislicki, 1991). 

The case study 2. Evaluation of ZDDP (primary, secondary) with R-group chain structure (long, medium, short) in oil formulation was done during the field tests. The various aspects of valve train wear performance of lubricating oils through field testing in a passenger car vehicle were compared with laboratory data (Smolenski and Kabel, 1983). 

The ZDDP deterioration By reference to Table 6.10 and the case study 2 Evaluation of ZDDPs , in field tests of 56 passenger car vehicles (taxi cabs) and laboratory analysis of lubricating data were included viscosity, TBN, TAN, ZDDP (active), dispersants, oil consumption rate, engine deposits, camshaft and valve lifter wear. Which of the major ZDDPs and ZDDPs mixtures provide the best antiwear and antioxidant performance ... 

Due to the different fate of lubricants during their use, e.g. contamination by fuel and combustion products of engine oils, the toxicity of used lubricants may be significantly different than that of fresh oils. Fluids which are considered environmentally friendly must not only be biodegradable, but also relatively nontoxic, in both their initial form and degradation products. Their effects on flora and fauna must be minimal. There are two common tests to evaluate toxicity the Microtox and the Rainbow Trout bioassay. Considerable environmental toxicity testing has been carried out on esters fluids. Esters cause minimal acute toxicity by ingestion and skin absorption. 

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