Transmission Electron Microscopy of Boundary-Lubricated Bearing Surfaces. Part II: Mineral Oil Lubricant with Sulfur-and Phosphorus-Containing Gear Oil Additives

Transmission electron microscopy (TEM) was performed on cross-sectional samples of tapered roller bearing cone surfaces that were tested at two levels of local boundary lubrication severity, Λ ～ 1.1 and 0.3. Unlike our previously reported work in which a base mineral oil was used, the bearing tests were conducted in mineral oil with sulfur- and phosphorus-containing gear oil additives. Structural and compositional characterization of undetached antiwear surface layers on the base steel (cone raceway) revealed that the films contained crystalline and amorphous regions. A sharp interface (<～10 nm) that separated the surface layer and base steel was imaged. The surface layer for the cone tested at Λ ～ 1.1 consisted of Fe, O, and P, whereas that for the cone tested at Λ ～ 0.3 consisted of Fe, O, P, C, Ca, and S. Various TEM analytical techniques were used to study the segregation of these elements throughout the antiwear surface layer volume.     

Occurrence and Distribution of Boron-Conitaining Phases in Sintered ş-Silicon Carbide

A variety of optical and analytical instruments have been employed to observe and characterize the mlcrostructure and composition of the B-containing phases which occur in sintered α-SiC as a result of either their use as a nensification aid or that which evolves as a result of annealing well below the sintering temperatures. The former have been identified as B₄C containing a small amount of Si. The latirr occur as ∼20-nm precipitates which have also been tentatively identified as B₄C and are believed to contain trace quantities of Si. No B phase was observed on the SiC grain boundaries; furthermore, the precipitate formation was not enhanced by the application of stress.     

Serine Palmitoyltransferase (scs1/lcb2) Mutants have Elevated Copy Number of the L-A dsRNA Virus

The microsomal fraction isolated from serine palmitoyltransferase (lcb2/scs1) mutants is enriched in a 90 kDa protein. The protein was identified as the major coat (Gag) protein of the L-A dsRNA virus particles by partial sequencing and by its interaction with anti-Gag antibodies. The total amount of Gag in whole-cell lysates of scs1/lcb2 mutant cells is greater than in wild-type lystes indicating that the enrichment of the protein in the microsomal fraction of scs1/lcb2 mutant cells may result from increased copy number of the L-A dsRNA virus. This is supported by the finding that the mutants also have increased levels of L-A dsRNA. Altered sphingolipid synthesis in the scs1 mutant cells appears to increase the copy number of the L-A viral particles. © 1997 John Wiley & Sons, Ltd.     

THERMAL CONDUCTIVITY of CONCENTRATED WHOLE MILK

The information of thermal conductivity of milk is required for the design of heat exchanger equipment in the dairy processing. Thermal conductivity of whole milk was experimentally determined by a steady-state, parallel disk, relative method at various concentrations (from 37 to 72.4% total solids) and temperature range between 40 to 90°C. This thermal property of milk increased with rise in temperature and decreased with increase in total solids content and its values varied from 0.278 to 0.491 W/m K. an expression has been proposed for derivation of milk thermal conductivity from temperature and total solids content.     

Transmission Electron Microscopy of Boundary-Lubricated Bearing Surfaces. Part I: Mineral Oil Lubricant

Transmission electron microscopy (TEM) was performed on the near-surface material (depth <500 nm) of tapered roller bearing inner rings (cones) that were tested at two levels of boundary-lubricated conditions in mineral oil with no additives. Site-specific thinning of cross section cone surface sections for TEM analyses was conducted using the focused ion beam (FIB) milling technique. High-resolution structural and compositional characterization of near-surface material and surface layers was performed on an untested cone as well as cones tested at Λ～1.1 and 0.3. This approach revealed near-surface microstructural distortion and grain size gradients that were attributed to surface finishing operations during manufacture. The characteristics of oxide surface layers and micro-cracks on the tested bearing surfaces were evaluated and found to depend on lubrication conditions.