89 research outputs found
Densification, Microstructure, and Mechanical Properties of ZrC-SiC Ceramics
ZrC-SiC ceramics were fabricated by high-energy ball milling and reactive hot pressing of ZrH2, carbon black, and varying amounts of SiC. The ceramics were composed of nominally pure ZrC containing 0 to 30 vol% SiC particles. The relative density increased as SiC content increased, from 96.8% for nominally pure ZrC to 99.3% for ZrC-30 vol% SiC. As SiC content increased from 0 to 30 vol%, Young\u27s modulus increased from 404 ± 11 to 420 ± 9 GPa and Vickers hardness increased from 18.5 ± 0.7 to 23.0 ± 0.5 GPa due to a combination of the higher relative density of ceramics with higher SiC content and the higher Young\u27s modulus and hardness of SiC compared to ZrC. Flexure strength was 308 ± 11 MPa for pure ZrC, but increased to 576 ± 49 MPa for a SiC content of 30 vol%. Fracture toughness was 2.3 ± 0.2 MPa·m1/2 for pure ZrC and increased to about 3.0 ± 0.1 MPa·m1/2 for compositions containing SiC additions. The combination of high-energy ball milling and reactive hot pressing was able to produce ZrC-SiC ceramics with sub-micron grain sizes and high relative densities with higher strengths than previously reported for similar materials
High temporal resolution monitoring of multiple pollutant responses in drainage from an intensively managed grassland catchment caused by a summer storm
This work presents data on a suite of diffuse pollutants, monitored in a stream
draining an intensively managed grassland on a 30 min time step during a period
of intense rainfall to better understand their sources and pathways. Nitrite (92
mu g l(-1)), particulate phosphorus (107 mu g l(-1)) and soluble phosphorus (74
mu g l(-1)) exceeded environmental limits during base flow. Concentrations of
nitrate and nitrite were decreased during the storm event, whereas all other
pollutants generally increased and exceeded environmental limits where
specified, especially when associated with a small subsidiary hydrograph on the
rising limb of the main hydrograph. Total pollutants loads, when using a 60 min
sampling frequency, would have led to significant over and under-estimations
depending on which 60 min sample set was used. In the worst case, loads of
ammonium could have been under-estimated by 35% or over estimated by 25% with
errors being associated with loads on the rising limb of the hydrograph and more
specifically a small subsidiary hydrograph. This subsidiary hydrograph may have
occurred as a result of runoff from the farm hard standings within the
catchment. Incidental transfer of pollutants associate with this runoff have
masked the overall grassland pollutant response. To better understand these
different source areas and pollutant dynamics, there is a need for novel tracing
techniques to elucidate their relative contribution and pathways
Experimental investigation on micro-electrochemical sinking operation for fabrication of micro-holes
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