carburetor. Suleimanova et al. ( 6 7 0 modified the standard IT9/3 apparatus for the determination of cetane number of liquefied petroleum gases alone and in the presence of diesel fuel and additives that catalyze burning. The method was sufficiently sensitive to composition and was suitable for routine checks as well as research. The CFR cetane rating method has been modified and tested by Burt and Troth (11C). I n their modification, they adjust the compression ratio to give a delay on the rating sample of 10" with a n injection advance on 15' crank angle; then without altering the compression ratio, they bracket the sample by measuring the delays produced by reference fuels. Thouvard (69C) discusses some unique features of a n engine testing center such as the design and application of testing apparatus which accurately controls all the operating parameters, apparatus that performs operations automatically, automation systems, and their use in the development of new petroleum products. Knock intensity is defined by Barton et al. (7C) to be the root-mean-square value of the cylinder rate of pressure change between 1000 cycles/sec and 5000 cycles/sec averaged over a 10-sec time interval. This definition permits objective comparisons of knock for different fuels, engines, and investigators; it allows objective comparisons of exhaust emissions as a function of engine performance and power and of trace and audible knock; and it eliminates the influence of engine structure and mounting. Gartenmann (26C) has made a comprehensive review of the problems concerning high speed knock, low speed knock, spark knock, and surface or preignition characteristics of automobile engine gasolines. The current USSR practice for equating the performance of the standard knock testing units IT9-2 and IT9-6 solely with respect to the determination of the octane number of a 74:26 mixture of toluene and n-heptane has been found inadequate. Danilov (17C) recommends that these two units be compared with regard to octane number, compression pressure, and combustion chamber temperature. The evaluation of their equivalency should be conducted on two control fuels, the octane numbers of which correspond to the ranges of below 90-95 and above 90-95 octane number in engines of the ITQ-2 or ITS-6 type. Danilov and Gorn (2OC) have replaced the carburetor with a special evaporator system with electronic control of the motor fuel dose supplied in each cycle and have transistorized the ignition system. Because of improved accuracy, a single knock meter reading was sufficient instead of the usual three. As a result the sample of motor fuel required for the deter-
mination was only 60-80 ml. Danilov (18C) gives additional information on this modified equipment and (19C) develops an equation for reducing the octane number of a fuel measured a t any pressure to its value a t 760 mm Hg with allowances for the aromatic content and the tetraethyllead content of the fuel. Fenske and Johnston (24C) describe UOP's Monirex Octane Monitor which continuously monitors the octane rating of refinery process and gasoline blender streams by measuring knock-precursor reaction pressure. This instrument replaces both the conventional and the automated knock engines with their artificially damped knockmeter. I n order to reduce the number of tests required for routine quality control, several authors have studied the relationships between the tests to see if the same information could be obtained from some other test. Costa (16C) presents nomographs for the determination of octane number from API gravity and the 10% and 90% ASTM distillation points. Jenkins (332) gives the equation Motor ON = 22.5 0.83 Research ON - 20 sp gr - 0.12 ole0.5 T M L 0.2 T E L which fins enables the Motor octane number to be calculated for commercial gasolines in the Research octane number range 88-102. The equation is applicable to gasoline blending components but there is a bias between calculated and experimental Motor method ratings. Relationships between the Research rating on the total gasoline, the gasoline composition, and various other octane ratings are quoted by Jenkins (35C); these relationships show how distillate octane numbers may be calculated. Thus, all experimental CFR ratings may be eliminated from routine quality control except for Research rating on total gasoline. Hinkamp and Riggs (29C) have made a detailed analysis of data on diesel fuels published by the U.S. Bureau of Nines demonstrating that the Calculated Cetane Index is far superior to the Diesel Index for estimating the ignition quality or cetane number (ASTM D 613) of diesel fuels. The validity and reliability of 12 empirical equations for estimating the temperature a t a 20: 1 vapor-liquid ratio as measured have been evaluated by Ebersole (ZZC). This study showed that the only equation that yields an efficient and unbiased estimate of the measured temperature is one based on the modified Reid vapor pressure method. Jenkins (34C) has developed equations and nomographs which relate the temperature corresponding to several vapor/liquid ratios with ASTM distillation test temperatures and with the Reid vapor pressure. Many of these new equations should be suitable for controlling the front end volatility of motor gasolines and hence vapor lock
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in cars. Jenkins and White ( 3 7 0 have used statistically derived relationships to calculate Reid vapor pressure of light distillates, components, and products from distillation data. The agreement between the calculated and experimental data depends on the precision of the testing in the laboratory. Graphs and tables have been developed by Jenkins and Walsh (36C) for calculating the luminometer number, smoke point, aromatics content, and hydrogen content of kerosine-type aviation fuels from aniline point and specific gravity. The Journal of the Institute of Petroleum (41C) has reported results from an interlaboratory survey showing the agreement between calculated and experimental smoke point values, luminometer values and aromatics content. These values were calculated from aniline point and specific gravity. Gilyazetdinov (27C) has prepared nomographs for calculating the type composition of hydrocarbon fuels and oils. These nomographs are based on a previously published method involving the use of the additive functions G and L expressed in terms of molecular weight, density, and refractive index. The data obtained by capillary gas chromatography, which are used to determine the individual Ca-12 hydrocarbons in full range motor gasolines, have been used by Maynard and Sanders (49C) in a computer program to calculate the hydrocarbon composition of the vapor in equilibrium with a gasoline a t 100 O F as well as the equilibrium vapor pressure of the gasoline a t t h a t temperature. Calculated total vapor pressures agree well with experimental Reid vapor pressures obtained for typical premium grade gasolines. Jenkins (32C) analyzes light straight run gasoline, catalytic reformates, motor benzene, and isomerizates by chromatography and calculates Research and Motor octane numbers, Reid vapor pressure, and specific gravity from regression curves.
Lubricants, Oils, and Greases F. M. Roberts Texaco Inc., Beacon, N. Y.
Oils. Improved methods for determining neutralization numbers of lubricating oils containing additives were discussed in several reports during the period of this review. Abbott and Farley (ID)reported that perchloric acid in glacial acetic acid was the best titrant for determining base numbers of unused marine diesel cylinder oils. Perchloric acid is unsatisfactory for the titration of used oils. Uchinuma et al. (890, 3 0 0 ) modified the perchloric acid method by back titration of the
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perchloric acid-neutralized glacial acetic acid solution with sodium acetate and found a sharp inflection with used oils. Przybylski and Kotowski ( 6 7 0 ) determined the base number of engine oil dissolved in toluene-isopropyl alcohol by potentiometric titration. Luneva ( 5 1 0 ) determined alkalinity of thiophosphate and sulfonate additives, and lubricating oils containing them by potentiometric titration with calomel or glass electrodes. Titration to p H 2 gave best results. A method in which a diesel oil sample in ethanol-benzene was stirred before titration under a stream of 5-7y0 COz in air until pH 6.9 was reached has been described by Adamenko (20). The potentiometric titration curve of an oil containing barium alkylphenate and zinc dialkyldithiophosphate gave two titration steps and permitted calculation of the total amount of barium. A variety of techniques have been described for separating, identifying, and determining lubricant additives. Kinder and Nee1 ( 4 2 0 ) reported ultraviolet and mass spectrometric methods for the identification and determination of oxidation inhibitors in synthetic lubricating oils. The inhibitors studied were phenothiazine, N-phenyl-anaphthylamine, N-phenyl-@-naphthylamine, and p,p’-dioctyldiphenylamine. The analysis and characterization of lubricant additives by infrared spectrometry, elution chromatography, and dialysis were discussed by Leutner (490). Infrared spectrometric studies of the structure of high molecular weight succinimides and their initial components were reported by Pliev et al. (660). Przybylski et al. (680) separated lubricating oil additives by silica gel chromatography and identified them by infrared spectrometry. Vipper and Tarasov ( 9 5 0 ) applied infrared spectrometry to study structural changes of additives in new and used lubricating oils containing antioxidant, detergent, and multifunctional additives. Infrared spectrometry was used by Berthold and Drescher ( 1 1 0 ) for determining 2,6-di-tert-butyl-p-cresolin turbine oils, and Tooke and Wilde ( 8 7 0 ) studied the effect of base oil composition in this analysis. Markeeva and Shestakova ( 5 3 0 ) reported a rapid oxygen flask method for determining phosphorus and sulfur in additives and heavy petroleum products. Chromatographic methods for the analysis of lubricating oils were the subject of a number of reports. Kolombo et al. ( 4 3 0 ) used thin-layer chromatography for determining 2,6-ditert-butyl-p-cresol in turbine oils. The plates were eluted with carbon tetrachloride, dried, sprayed with 2,6-dichloroquinone-4-chloroimide, and the area of the spots compared with knowns. Thin-layer chromatography was used by 168R
Amos (40) to separate and identify antioxidants, phenates, sulfonates, zinc dialkyldithiophosphates, and polymeric additives in lubricating oils. Berthold (100) used liquid-solid chromatography in the analysis of additives in petroleum-base oils. The separation sequence for twenty classes of monofunctional compounds was determined. Inhibitors in transformer oils were determined by Stoll and Vuillemier (810) using a silica gel column to concentrate the additive, followed by a gas chromatographic determination. Shimizu ( 7 6 0 ) reported that dialkyl selenide, an antioxidant for turbine oils, can be detected by partition chromatography on glass fiber paper. Additives which form metal complexes can be separated on cation-exchange resins with transition metal counterions. Webster et al. ( 9 5 0 ) reported the use of this technique to separate hindered alkyl phenols, secondary aromatic amines, alkenylated succinic acid, and phenol/alkylene oxide condensates. Simon ( 7 7 0 ) determined the molecular weight distribution of polymethacrylates by fractionating on a silica gel column and determining molecular weights of the fractions from viscosity measurements. Quigley et al. ( 6 9 0 ) compared molecular distillation, precipitation, gel filtration, and dialysis for the separation of ashless additives. Molecular distillation was reported to be a good method for these separations. Slobodin and Malysheva ( 7 8 0 ) used dialysis for the separation of alkylphenol additives from oils. The composition of petroleum oil was investigated by LePera ( 4 7 0 ) using carbon-type analysis and infrared spectrometry. An absorbance ratio of aromaticity-paraffinicity was developed for rapid assignment of the relative hydrocarbon composition of petroleum oil samples. Miglierini and Kelloe ( 5 7 0 )studied the structure and physicochemical properties of extracts from selective refining of mineral oils, using a variety of physical and chemical techniques. A discussion of used engine oil analysis was presented by Texaco Inc. ( 8 4 0 ) . Included were discussions of conditions limiting oil life, and of engine problems disclosed by oil test data. Stavinoha and Wright (800) reported on the application of a wide variety of physical, chemical, and spectrometric techniques to the analysis of used oils. Descriptions and evaluations of the methods were discussed. Esposito and Jamison ( 2 4 0 ) developed a gas chromatographic method for determining ethylene glycol in used oils. An emission spectrographic method for determining the oil consumption of diesel engines was reported by Fofanov (270). The gases formed by the decomposition of transformer oil were analyzed by gas chroma-
ANALYTICAL CHEMISTRY, VOL. 43, NO. 5, APRIL 1971
tography in a method developed by Schermann (740). The relation between composition and oxidation stability was studied by Vesely (920). Constituents were separated by elution chromatography, and oxidation stability was measured from kinetic oxygen absorption curves. An evaluation of the Coordinating Research Council Inc. oxidation test for aircraft gas turbine engine lubricants by four laboratories in a round-robin program was reported by Murphy (62D). Bondarchuk and Barannik ( 1 4 0 ) devised a closed system maintained under constant pressure for testing oxidation stability of oils. Mechanisms for the autoxidation of hydrocarbons, and the analytical methods for determining the products formed were reported by Nambu (630). Elliott et al. (230) evaluated a modification of the IP 229/ 68T oxygen absorption method for screening antioxidants for crankcase oils. A micro technique for thermooxidative stability of fluids was developed by Butler et al. (160). Capillary tubes containing 2 to 3 mg of sample in an atmosphere of air were heated and the residual gas was analyzed by gas chromatography. Korcek et al. ( 4 4 0 ) presented a review of the theory and application of infrared spectrometry for the determination of oxidation products in oils. The Motor Vehicle, Fuel, Lubricant, and Equipment Research Committee of the Coordinating Research Council, Inc. (610) reported a revised version of the L-38 test for oxidation characteristics of crankcase oil. Bacovsky and Pospisil ( 7 0 ) suggested the introduction of antioxidant and detergent efficiency coefficients for evaluating lubricant additives. The thermal degradation of additives for lubricants and fuels was studied by thermogravimetric analysis and reported by Masek (650). A chemiluminescent method was applied by Suleimanova et al. (850) to the study of the thermal stability of motor oils with additives. Vajta et al. ( 9 2 0 ) reported the evaluation of the thermal stability of lubricating oil additives based on the determination of kinetic factors such as the order of reactions, activation energies, and the temperature dependence of the logarithm of the rate constant. The high-temperature stability of quenching oils was studied by Wisken et al. ( 9 7 0 ) using a n electrically heated wire immersed in the sample. Kaegler and Morel1 (580) used the silver ball method to test quenching oils. A review presented by Texaco Inc. ( 8 5 0 ) covered lubricant specifications and specification engine tests issued by automobile manufacturers and by the military. Shields et al. ( 7 5 0 ) reported experience with computer automated engine stands for ASTM &IS Sequence VB. Measurement and control of test
conditions improved, and manual operating routines were reduced. Improvement in repeatability was less than expected. A similar lack of improvement in repeatability was reported by Griffin ( 3 3 0 ) in a series of 60-hour tests at Caterpillar l G test conditions. Hall et al. ( 3 4 0 ) gave a discussion of the standardization of small scale engine tests by the Institute of Petroleum. The DEF-2101-D Petter A.V. 1 evaluation method for checking detergency of diesel lubricating oils was described by Freund et al. (SOD). Forbes and Wood (280) developed a bench detergency test for automotive oils which correlated very well with MS Sequence V engine test data. A test method was reported by Bohlmann et al. ( 1 3 0 ) for evaluating 2-stroke motor oils by examining rusting and cold corrosion in an air-cooled 123 cc Otto engine with an aluminum housing. Bartz and Schultze ( 8 0 ) gave a critical review of lubricant test procedures in common use, and their relation to road tests. Bley (120) discussed the requirements and test methods for European automatic transmissions and fluid requirements. Francis and Presland (290) developed a modified four-ball machine in which each of the three fixed balls makes it own wear track on the rotating ball. This modification reduces track wear, and should accelerate the approach to steadystate sliding. An analysis of the results obtained by determining the antiwear properties of lubricants on a four-ball machine was reported by Kichkin et al. (410). Mikheev et al. (590) proposed a combination method for testing lubricants on the four-ball friction machine which is based on the “equality of friction conditions” principle. These authors (600) also developed an “Index of Lubricating Capacity” for use in four-ball machine evaluations. A fourball machine on which all operations are performed automatically, and load is preselected by turning a dial was described by Rozenberg et al. (710). The four-ball machine was used by Fujikawa and Asami (320) to evaluate cutting fluids. Smith (790) described a novel way of measuring wear which uses oscillating chambers containing 1200 0.025-inch diameter steel balls. Benedict ( 9 0 ) developed correlations between disk machines and gear tests which permit the use of disk machines rather than precision test gears for lubricant screening tests. A bench test for evaluating silver-steel lubrication properties of railroad diesel oils which involves the measurement of wear of a silver pin rubbing on a polished steel disk a t 7500 psi, and a rubbing speed of 20 ft/min was reported by Turnquest et al. (880). Reynolds ( 7 0 0 ) described the evaluation of a bearing test for determining the relative deposit and degradation characteristics of synthetic
gas turbine oils. A miniature oil circuit for the IAE 3.25-inch centres gearlubricant testing machine was described by Henshaw (860). Koved ( 4 5 0 ) made a comparison of fatigue test techniques for gas turbine oils and concluded these rigs should only be used for gross ranking. Faville and Faville (260) discussed the application of Falex test results to the evaluation of lubricant quality in service. A survey of the design, operating of, and test results for various wear testing machines was presented by Azzam ( 6 0 ) . Carroll (180) constructed charts to show the contact stress as a function of applied load for various wear test machines. Harris ( 3 5 0 ) reported an analytical method to determine effect of misalignment on the fatigue life of cylindrical roller bearings having crowned rolling members. Hopkins and Schroeder ( 3 7 0 ) discussed the stress variations with wear in the pinon-disk apparatus. Perin and Sedykin (640) used neutron activation analysis to measure the wear of test gears. Shear stress stability of multigrade engine oils is defined by a laboratory technique developed by LePera and Pigliacampi (480). Wislicki and Karpinski (980) used an ultrasonic technique to measure shear stress stability of oils. Dromgold and Rodman (210) studied the effects of rolling lubricant viscosity on the reduction of aluminum during cold rolling. Bondy et al. (150) incorporated compounds of dysprosium, hafnium, and indium in lubricants as tracers for detecting leaks in adjoining lubricant systems. The application of electron-probe microanalysis to the study of the load-carrying mechanism of sulfur compounds was described by Allum and Forbes ( 3 0 ) . DeLuca (200) incorporated radioisotopes in a method for determining lubricant adhesiveness. Winney (960) used a magnetic reluctance technique to measure thickness of thin fluid films. The determination of carbon in thin films on steel surfaces was accomplished by heating the specimens in a combustion furnace, passing the gases through another furnace containing silver vanadate and platinized copper oxide, and measuring the resultant carbon dioxide by thermal conductivity. This method was developed by Lee and Lewis (460). Kalaszi and Rezek (390) described a new method of evaluating cutting fluids by means of KobayashiThomsen’s cutting force equation for a low cutting speed range. A liquidphase micropanel coker capable of operation a t hot-spot temperatures up to 1000 O F with samples less than 75 cc was developed by Cuellar and Ku (190) for the evaluation of aircraft turbine lubricants. Thoenes and Bauer (860) developed a new method for measuring deaeration of oils. After aeration of the sample under standardized conditions,
the time required for removal of all but 0.2% by volume of the air is determined from density measurements made with a Mohr-Westphal balance a t regular intervals. Walker (940) found no correlation between ASTM D877 and D1816 methods for determining dielectric strength of insulating oils, and therefore conversion factors to convert values from one test to the other are not possible. Greases. Methods for determining composition or identifying grea,qes were discussed in several papers which appeared during the period of this review. Two of the methods were presented by Sat0 (720, 7 3 0 ) . The first described the results of an infrared spectrometry study of metallic stearates leading to qualitative determinations of calcium, aluminum, and lithium greases. I n the second method, oil and soap components were separated and determined by rubber membrane dialysis. Buttlar and Cantley ( 1 7 0 ) determined lithium soap in grease by infrared spectrometry after a carefully controlled heating and cooling cycle. Dunken et al. (220) applied infrared spectrometry and differential thermal analysis to analytical studies of lubricating greases. The effects of corrosion inhibitors on the rheological properties of lithium soap greases were correlated with structural changes observed by differential thermal analysis, infrared, and electron microscopy in a paper by Friberg et al. (310). Matsumoto (660) converted the fatty acids in grease to the methyl esters and analyzed for them by gas chromatography. hlanoliu et al. ( 5 2 0 ) described a n electron microscope technique for the study of greases, and Kempe (400) reviewed available methods for electron microscopy of soap-containing lubricating greases. An electron microscopic study of crystalline aggregates in lubricating greases was reported by Pie Contijoch and Cortes Rubio (650). Armstrong et al. ( 5 0 ) described a laboratory wheel-bearing test apparatus for automotive greases. Lieser and West (500) used a commercial roller bearing for railway journals with a vibration tester to simulate, in the laboratory, the softening of railroad journal greases in service. The efficiency of greases was studied by Mikheev and Klimov (580) using a five-ball machine. Strong ( 8 2 0 ) developed correlations that relate penetration more exactly to apparent viscosity and to starting torque. Marvillet and DuParquet (540) reported the development of a sliding plate microviscometer for the study of greases in bearings. Ewbank and Waring ( 2 5 0 ) described the development of a method for determining the leakage characteristics of lubricating greases.
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