The effects of polyvinylpyrrolidone (PVP) on the formation of iron oxide nanoparticles during polyol synthesis are described. The addition of PVP during synthesis changes the particle morphology from compact to porous with chains of small iron oxide nanocrystals at the surface of the particles due to the steric repulsion of PVP ligands. The addition of PVP also reduces average particle size from 857 nm to 225 nm by preventing agglomeration. In addition, the presence of PVP restricts crystal growth of iron oxide and limits oxidation. The high-surface areas achieved for the powders can be useful for catalytic applications. (C) 2017 Elsevier B.V. All rights reserved.

11:15 JSAE20159149 / SAE2015-01-1870 Investigation of Lubricating Oil Properties Effect on Low Speed Pre-Ignition Koji Morikawa, Yasuo Moriyoshi, Tatsuya Kuboyama, Toshio Yamada, Chiba University / Masatoshi Suzuki, Sustainable Engine Research Center Co., Ltd. 11:45 JSAE20159071 / SAE2015-01-2027 Engine Oil Formulation Technology to Prevent Pre-ignition in Turbocharged Direct Injection Spark Ignition Engines Ko Onodera, Tomohiro Kato, Satoshi Ogano, TonenGeneral Sekiyu K.K. / Kosuke Fujimoto, Katsuyoshi Kato, Toyoharu Kaneko, Toyota Motor Corporation

This work investigates the effect of compression and sliding on diesel soot in a confined space. Experiments were conducted in a high-resolution transmission electron microscope equipped with an in situ nanoindenter mounted with a truncated diamond tip to manipulate single soot particles and agglomerates. It was shown that both, agglomerates and single particles, were quite resistant to load. Agglomerates did not break during the compression tests; instead, partially reversible compaction of the particles to fill the free space was witnessed, proving that strong cohesive forces exist between the soot particles. The primary particles exhibited good elastic behavior under compression, and the agglomerates mirrored this behavior. Sliding tests have shown the ability of both the agglomerates and single primary particles to roll in the contact zone. This work showed that diesel soot is highly resilient to stress.

We present an analysis of reverse micelle stability in four model systems. The first two systems, composed of unstable microemulsions of isooctane, water, and Na-AOT with additions of either iron sulfate or yttrium nitrate, were used for the synthesis of iron oxide or yttrium oxide powders. These oxide powders were of nanocrystalline character, but with some level of agglomeration that was dependent on calcination temperature and cleaning procedures. Results show that even though the reverse micellar solutions were unstable, nanocrystalline powders with very low levels of agglomeration could be obtained. This effect can be attributed to the protective action of the surfactant on the surfaces of the powders that prevents neck formation until after all the surfactant has volatilized. A striking feature of the IR spectra collected on the iron oxide powders is the absence of peaks in the similar to 1715 cm(-1) to 1750 cm(-1) region, where absorption due to the symmetric C=O (carbonyl) stretching occurs. The lack of such peaks strongly suggests the carbonyl group is no longer free, but is actively participating in the surfactant-precipitate interaction. The final two microemulsion systems, containing CfAB as the surfactant, showed that loss of control of the reverse micelle synthesis process can easily occur when the amount of salt in the water domains exceeds a critical concentration. Both model systems eventually resulted in agglomerated powders of broad size distributions or particles that were large compared to the sizes of the reverse micelles, consistent with the notion that the microemulsions were not stable and the powders were precipitated in an uncontrolled fashion. This has implications for the synthesis of nanopowders by reverse micelle synthesis and provides a benchmark for process control if powders of the highest quality are desired. (C) 2013 Elsevier Inc. All rights reserved.

The friction and wear characteristics of thin diamond-like carbon (DLC) coatings have been investigated extensively in recent years mostly in laboratory bench tests. These coatings are known to provide significant friction reduction in the absence of lubricants. In the presence of lubricants, the friction benefits of these coatings are not clearly demonstrated. The current investigation is focused on exploring the friction reduction potential of a DLC coating obtained from a supplier in laboratory bench tests and in a motored valve train test. The DLC coating was deposited on the bucket tappet. In laboratory bench tests, results showed significant friction reduction in the absence of any lubricant but not in the presence of engine oil. In motored valve train tests a significant reduction in friction torque was observed when compared against a slightly rougher uncoated bucket, but no reduction was observed when compared against uncoated bucket tappet with comparable surface finish. Under boundary lubrication conditions, no lubricant-derived surface films were present on the DLC-coated surface. However, under mixed lubrication conditions, evidence of patchy antiwear surface films could be observed on DLC-coated buckets. The antiwear film appears to be primarily composed of calcium phosphate.

This paper is first in a series of papers designed to investigate wear processes in modern heavy duty diesel engines. The objective of the series is to discuss the effects that engine drive cycle, lubricant formulations and in-service ageing of lubricants have on wear of critical engine components.In this paper, the Radioactive Tracer Technology technique was used to study the steady state wear behavior of a number of contacting surfaces in a Caterpillar 1P engine, as a function of the drive cycle. A test protocol consisting of 7 modes or stages was used to simulate a variety of drive cycles. The results from this work provide useful insights into the wear behavior of these surfaces under a variety of speed and load conditions.

Tungsten nanopowders were synthesized by a low-temperature technique and then heat treated in a gaseous reductive atmosphere in order to study the phase evolution, crystallite size, and particle size of the powders as the heat treatment temperature was modified. Synthesis of the powders was carried out in aqueous media using NaBH4 as a reducing agent using careful control of the pH of the solutions. The XRD patterns of the as-synthesized powders showed an amorphous phase. After washing, energy dispersive spectroscopy showed that the powders had peaks for oxygen and tungsten. In order to promote crystallization and eliminate the oxygen, the powders were heat treated at 773 K, 923 K, and 1073 K (500 °C, 650 °C, and 800 °C) in a H2/CH4 reducing atmosphere for 2 hours. XRD after heat treatment showed α-W peaks for the powders treated at 1073 K and 923 K (800 °C and 650 °C) and a mixture of β-W and α-W for the powders treated at 773 K (500 °C). The crystallite sizes determined from X-ray peak broadening were 12, 16, and 20 nm, whereas the average particle sizes from dynamic light scattering were 260, 450, and 750 nm, for heat treatment temperatures of 773 K, 923 K, and 1073 K (500 °C, 650 °C, and 800 °C), respectively. The average crystallite size and particle sizes increased proportionally with the treatment temperature, in contrast to what has been found for some ceramics, in which as the heat treatment temperature is increased, the crystallite size increases, but the particle size stays constant.

Nanofluids consist of nanoparticles dispersed in heat transfer carrier fluid and are typically used for enhancing thermal conductivity in devices and systems. This study investigated the synthesis of iron and copper nanoparticle-based thermal fluids prepared using a two-step process. Chemical precipitation was used for the synthesis of the powders, and ultrasonic irradiation was used to disperse the nanoparticles in the carrier fluid (ethylene glycol). The size distributions of the nanopowders in the carrier fluid were determined using dynamic light scattering resulting in average particle sizes of around 500 nm. The crystallite sizes of the powders were below 20 nm. Thus, both types of nanofluids are comparable with regard to crystallite size, particle size, and morphology resulting in a direct comparison of material properties and their effect on thermal conductivity of the nanofluids. A guarded hot parallel-plate method and dynamic tests were used to compare the thermal conductivities of the nanofluids. It was shown that thermal conductivity can be enhanced by up to 70% for copper nanofluids. It was also demonstrated that for a given particle concentration, copper nanofluids are superior in thermal conductivity compared to iron nanofluids.

A novel, integrated, fast, and inexpensive process for the preparation of dense Ba (1− x ) Eu x Al 2 Si 2 O 8 thin ceramic specimens for damage sensor applications is reported. The processing approach involves a combination of combustion synthesis for the preparation of the powders and spark plasma sintering (SPS) for the consolidation of the specimens to densities close to 100% of relative density. The synthesis of the porous powders by combustion resulted in particle (agglomerate) sizes that were on average 421 nm, as determined from dynamic light scattering, and in the almost complete reduction of the initial Eu 3+ activators to Eu 2+ . The powders densified to grain sizes of around 250 nm due to a collapse of the porous powder structure and minimal grain growth during SPS. Thermal treatment of the powders and sintered specimens improved the intensity of the emissions at 373 and 745 nm and diminished the emission at 485 nm. The luminescence phenomena from the specimens were a result of two mechanisms: (1) the removal of strain in the lattice due to thermal treatment, and (2) a charge transfer mechanism between Eu 2+ and Eu 3+ .

Interest in amorphous metal alloys has grown dramatically in the last few years. Recently, a novel composition known as structurally amorphous metal 7 (SAM7) with a composition of Fe48Mo14Cr15Y2C15B6 was developed. Determination of its density and sintering behavior, with and without Y2O3 nanoparticle additions, was undertaken in this study using spark plasma sintering. It was found that the pure SAW material has a theoretical density of 7.75 g/cm(3) and can be sintered to full density (rho(experimental)=7.76 g/cm(3)) at 600 degrees C for 10 min without loss of amorphous character. The SAM7 powder with the addition of similar to 2.5 wt.% of Y2O3 nanoparticles has a theoretical density of 7.67 g/cm(3) and can be sintered to full density (rho(experimental)=7.30 g/cm(3)) at the same temperature and time as for pure SAM7. (C) 2008 Elsevier B.V. All rights reserved.

Iron nanoparticles dispersed in hydraulic oil were prepared by mixing two microemulsions containing iron (II) sulfate and sodium borohydride at a temperature of 60°C. Six values of ω 0 = [water]/[surfactant] were used, namely 5, 10, 15, 20, 25, and 30. Dynamic light scattering measurements of the hydrodynamic radius of the reverse micelles showed that the average size, surfactant shell thickness and water core radius, increased with ω0. The micelle size distribution for ω0 values of 5, 10, and 15, was in the nanometer regime, while for ω0 values of 20, 25, and 30 it was in the micrometer regime. Scanning electron microscopy showed that the nanoparticle diameters were around 30 nm for the powders prepared using an ω 0 = 10. In addition, a comparison between the particle size distribution of the iron nanoparticles dispersed in isopropyl alcohol and the iron nanoparticles in the reverse micellar solution was made. It was shown that once the particles are cleaned and separated from the micellar solution, they agglomerate into particles that are about 1 μm in size.

This paper describes the growth of barium chromate (BaCrO4) nanocrystallites within thermally evaporated thin films of stearic acid (StA) and sodium bis‐2‐ethylhexyl‐sulfosuccinate by a process of Ba2+ ion entrapment followed by in situ reaction with CrO42− ions. Dense spherical assemblies of BaCrO4 nanocrystallites of very uniform size (∼50 nm) were obtained within the two different host matrices. The spherical assemblies were composed of smaller (ca. 5–10 nm size) BaCrO4 crystals indicating that efficient size control over crystal size may be exercised by the matrix. Contact angle measurements of the BaCrO4–StA and BaCrO4–sodium bis‐2‐ethylhexyl‐sulfosuccinate films indicated that they were hydrophobic, thus pointing to the possible role of hydrophobic interaction between the StA and sodium bis‐2‐ethylhexyl‐sulfosuccinate monolayer‐covered BaCrO4 crystals in the assembly process.

The crystallization of calcite in the form of spheroaggregates in aqueous foam stabilized by the surfactant sodium bis-2-ethylhexyl-sulfosuccinate (aerosol OT, AOT) by a method of ion entrapment is described. Reaction of Na2CO3 with Ca2+ ions electrostatically entrapped in the foam results in the formation of flat, platelike calcite crystals, possibly in the plateau border regions of the foam. Hydrodynamic flow patterns in the foam are believed to transport the calcite platelets from the plateau border regions into the larger plateau junctions where they assemble into spherical structures by hydrophobic association. The large interfacial area of the liquid lamellae in the foam provides an attractive and versatile template for the large-scale synthesis of not only minerals but also other nanoscale materials.