Bernard A. Baldwin

Relationship between Surface Composition and Wear: an X-ray Photoelectron Spectroscopic Study of Surfaces Tested with Organosulfur Compounds

An examination of steel surfaces, after wear-testing in oils containing organosulfur compounds, was conducted to investigate possible reasons for the differences in the efficiency of organosulfur compounds as antiwear additives. The tested surfaces were characterized both qualitatively and quantitatively by x-ray photoelectron spectroscopy. Qualitative analysis showed that wear-testing of several different organosulfur compounds produced metallic sulfide on the external surface. This observation indicates that the differences in efficiency cannot be ascribed to chemically different surface species. From quantitative analysis, a correlation was determined between the relative surface concentration of sulfide and wear; the higher the sulfide concentration at the end of the wear-test, the lower the wear during that test. The sulfide concentration was constant throughout the three-hour test of a given compound, but differed from one compound to another. The addition of amines to the oil formulation decreased ...

Using magnetic resonance imaging to monitor CH4 hydrate formation and spontaneous conversion of CH4 hydrate to CO2 hydrate in porous media

Magnetic resonance imaging was used to monitor and quantify methane hydrate formation and exchange in porous media. Conversion of methane hydrate to carbon dioxide hydrate, when exposed to liquid carbon dioxide at 8.27 MPa and approximately 4 degrees C, was experimentally demonstrated with MRI data and verified by mass balance calculations of consumed volumes of gases and liquids. No detectable dissociation of the hydrate was measured during the exchange process.

Relative antiwear efficiency of boron and sulfur surface species

Abstract The chemical character and surface concentration of boron and sulfur have been determined by X-ray photoelectron spectroscopy after wear testing of boron-sulfur compounds. The surface boron was attributed to a divalent borate while sulfur was present as a sulfide and sometimes as zero-valent sulfur. Regressive techniques and a model relating surface concentration to wear allowed the assignment of relative antiwear efficiencies. For equal concentrations the surface sulfide was found to be approximately 50 times more effective than the surface boron while the zero-valent sulfur was associated with prowear behavior. The antiwear efficiencies indicate that boron is not beneficial enough to warrant its inclusion as an active antiwear element in antiwear additives.

NMR imaging of fluid dynamics in reservoir core

A medical NMR imaging instrument has been modified to image water and oil in reservoir rocks by the construction of a new receiving coil. Both oil and water inside the core produced readily detectable proton NMR signals, while the rock matrix produced no signal. Because of similar T2 NMR relaxation times, the water was doped with a paramagnetic ion, Mn+2, to reduce its T2 relaxation time. This procedure enhanced the separation between the oil and water phases in the resulting images. Sequential measurements, as water imbibed into one end and oil was expelled from the other end of a core plug, produced a series of images which showed the dynamics of the fluids. For water-wet Berea Sandstone a flood front was readily observed, but some of the oil was apparently left behind in small, isolated pockets which were larger than individual pores. After several additional pore volumes of water flowed through the plug the NMR image indicated a homogeneous distribution of oil. The amount of residual oil, as determined from the ratio of NMR intensities, closely approximated the residual oil saturation of fully flooded Berea samples measured by Dean-Stark extraction. A Berea sandstone core treated to make it partially oil-wet, did not show a definitive flood front, but appeared to channel the water around the perimeter of the core plug. The relative ease with which these images were made indicates that NMR imaging can be a useful technique to follow the dynamics of oil and water through a core plug for a variety of production processes.

Wear Mitigation by Antiwear Additives in Simulated Valve Train Wear

Antiwear additives are necessary components of motor oils in order to maintain satisfactory wear rates of automobile engines, particularly in the valve train area. Even though much has been accomplished to minimize wear, the processes by which antiwear additives function to mitigate wear are not completely known. A mechanism is proposed which includes antiwear additive—surface interaction by either adsorption followed by reaction or direct reaction. This mechanism is shown to be consistent with previous experimental data. Evidence is shown indicating that surface sulfide is not the sole species responsible for boundary lubrication with organosulfur compounds. The formation of sulfide rather than the thermodynamically preferred sulfate is indicated to be the result of kinetic limitations which restrict oxygen and produce a “reducing atmosphere” during reaction on the surface. A mechanism for producing wear debris is proposed. This mechanism relies on diffusion and segregation of antiwear additive elements ...

Method for determining properties of liquid-containing porous media using nuclear magnetic resonance imaging

A method is provided of determining saturation values corresponding to particular locations in a sample of a porous media, whereby such saturation values can be used in conjunction with corresponding capillary pressures to derive a capillary pressure curve. The method of the invention involves the use of nuclear magnetic resonance (NMR) imaging to obtain NMR intensity values corresponding to the locations of interest. Intensity is related to saturation by an appropriate function which is employed to determine the saturation values from the intensity values.

Magnetic Resonance Imaging of Methane - Carbon Dioxide Hydrate Reactions in Sandstone Pores

Formation and growth of methane hydrates in porous sandstone was monitored using Magnetic Resonance Imaging (MRI). A series of 3-D MRI images collected during these experiments illustrated patterns of hydrate growth. Calibrated MRI intensity changes that occured during the hydrate growth correlated with methane gas consumption and gave dynamic and quantitative in-situ information on hydrate formation rate and spatial distribution of the hydrate formed. Gas permeability was measured at various hydrate saturations and during hydrate growth. Experimentally it was verified that methane hydrate in porous sandstone spontaneously converted to CO2 hydrate when exposed to liquid CO2 at high pressure and low temperature. It has experimentally been determined that without heating, an exchange process between CO2 and methane occured allowing the injected CO2 to be stored as hydrate resulting in spontaneous production of methane, with no associated water production. The MRI images provided quantitative information on the methane production rates and amounts of methane released during the CH4-CO2 hydrate exchange reaction. Thermodynamic simulations based on Phase Field theory supported the measured results and predicted similar methane production rates observed in several reproduced experiments.

Study of NickelCarbon bonding by x-ray photoelectron spectroscopy[1]

Abstract X-ray photoelectron spectroscopy (XPS) nickel 2p 3 2 binding have been measured for a series of trans square-planar Ni(X)(Y)(PEt3)2 complexes and correlated with a calculated ‘charge parameter’ for the nickel atoms. A reasonbly good correlation exists when X or Y is chloro, alkyl, vinyl, acyl, or phenyl, but not when both X and Y are acetylide. The deviation of ther diacetylide complex from the correlation is attributed to a substantial π character in the nickelcarbon bonds. The agreement of the aryl, vinyl, and acyl complexes with the correlartion indicates that any π character in these nickelcarbon bonds is small.

The Effect of Adsorption and Molecular Structure of Antiwear Additives on Wear Mitigation

The mechanisms by which antiwear additives mitigate wear in lubricated contacts are not unequivocally known. This study examined the effects of adsorption, sulfur, and steric hinderance on the wear mitigation properties for a series of model antiwear additives. A direct relationship was found between the amount of additive adsorbed and the wear-mitigating properties of that additive. The presence of sulfur, even in a nonreactive form, had a profound effect on reducing microscopic galling and improving surface appearance. Steric hindrance significantly reduced the wear-mitigating properties of the best antiwear additive tested in this study. The results are consistent with a previously proposed model which consists of micro-EHD, antiwear films, and local EP properties in the overall mitigation of wear by antiwear additives in lubricated contacts. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference in San Diego, California, October 22–24, 1984

The Effect of Base Oil Viscosity on Simulated Valve Train Wear

Current emphasis on fuel economy has evoked the desire to reduce lubricant viscosity both to improve fuel mileage and make starting easier with lighter starter systems. The present study was conducted to determine the effect of viscosity on wear under conditions associated with boundary lubrication. Measurements were obtained in a laboratory test designed to simulate the camshaft-lifter contact in an automobile or light truck engine. Viscosity reduction was shown to have a profound effect on wear once a critical viscosity had been reached. In the simulated camshaft-lifter contact, wear prevention appears to be due to a mixture of localized elastohydrodynamic lubrication and surface films formed from the antiwear additive. Loss of either results in excessive wear. The break in the wear-viscosity relationship occurred at 4–5 cSt @ 100 °C. Since this viscosity corresponds to the low end of the SAE 10 grade, it is possible that a 7-1/2W or 5W oil could result in excessive wear. These results suggest that any ...