A pilot Study was conducted from August 1999 through August 2000 to estimate the loading of selected pollutants from the atmosphere to the San Francisco Estuary. Particulate in the ambient air and precipitation samples were collected at three locations. Dry deposition flux of copper, nickel, cadmium, and chromium was approximately 1100?73, 600?35, 22?15, and 1300?90 μg/m/year, respectively. The...

Thermal stability of the dislocation cellular structure and precipitation behavior chromium carbide (M23C6), silicide (Mo3Si), σ phase in austenitic 316L stainless steel (SS) fabricated by laser powder bed fusion (L-PBF) additive manufacturing (AM) were studied at 500–800 ℃. The hardness remained stable 500 ℃ 600 for up to 400 h. However, regional coarsening resulted a slight reduction after 10...

The remediation of chromium-contaminated sites requires knowledge of the processes that control the migration and transformation of chromium. Advection, dispersion, and diffusion are physical processes affecting the rate at which contaminants can migrate in the subsurface. Heterogeneity is an important factor that affects the contribution of each of these mechanisms to the migration of chromium...

Spark plasma sintering has been used for the first time to prepare the ASTM F75 cobalt-chromium-molybdenum (Co-Cr-Mo) orthopaedic alloy composition using nanopowders. In the preliminary work presented in this report, the effect of processing variables on the structural features of the alloy (phases present, grain size and microstructure) has been investigated. Specimens of greater than 99.5 per...

Composite powders of tungsten carbide with variable coating contents of Fe/Ni/Cr based alloys (1–15 wt.%) were prepared by sputtering. The coated powders have revealed a good performance to shape-forming and sintering. However, the presence of nanocrystalline coatings could enhance the formation of a brittle phase during sintering, named g-phase, (M,W)6C. To investigate this effect, the powders...

The microstructure, electronic structure and chemical bonding of chromium carbide thin films with different carbon contents have been investigated with high-resolution transmission electron microscopy, electron energy loss spectroscopy and soft x-ray absorption-emission spectroscopies. Most of the films can be described as amorphous nanocomposites with non-crystalline CrC(x) in an amorphous car...

Atmospheric samples of precipitation and ambient air were collected at a single site in Washington, DC, for 7 months (for ambient air samples) and 1 year (for wet deposition samples) and analyzed for arsenic, cadmium, chromium and lead. The ranges of heavy metal concentrations for 6-day wet deposition samples collected over the 1-year period were 0.20-1.3 microg/l, 0.060-5.1 microg/l, 0.062-4.6...