title: Effects of lubrication on the powder metallurgy processing of titanium

authors: Lou, Jia

subjects: Compaction

abstract: The role of lubrication on the consolidation behaviour of titanium powder, density increase and change in microstructure on subsequent sintering was investigated. HDH titanium powder mixed with 0-2wt% stearic acid or magnesium stearate was cold compacted. It was found that 0.3-0.6wt% of internal lubricant significantly improves the compressibility. However, more than 0.6wt% of lubricant aids the densification in the low-pressure region but limits the maximum density at high pressure. Moreover, 0.3-0.6wt% of lubricant offers a more uniform density distribution to the powder compact, while greater than 0.6wt% of lubricant leads to a segregation of lubricant in the surface region. The shape retention, ejection behaviour, de-lubrication behaviour and sintered properties were also studied in this work.

text: Effects of lubrication on the powder metallurgy processing of titanium The role of lubrication on the consolidation behaviour of titanium powder, density increase and change in microstructure on subsequent sintering was investigated. HDH titanium powder mixed with 0-2wt% stearic acid or magnesium stearate was cold compacted. It was found that 0.3-0.6wt% of internal lubricant significantly improves the compressibility. However, more than 0.6wt% of lubricant aids the densification in the low-pressure region but limits the maximum density at high pressure. Moreover, 0.3-0.6wt% of lubricant offers a more uniform density distribution to the powder compact, while greater than 0.6wt% of lubricant leads to a segregation of lubricant in the surface region. The shape retention, ejection behaviour, de-lubrication behaviour and sintered properties were also studied in this work.

year: 2012

title: Lagrangian measurements of turbulent dissipation over a shallow tidal ﬂat from pulse coherent Acoustic Doppler Profilers

authors: Mullarney, Julia C.

subjects: drifters

abstract: We present high resolution (25 mm spatial, 8 Hz temporal) profiles of velocity measured over a shallow tidal flat using pulse-coherent Acoustic Doppler Profilers mounted on surface drifters. The use of Lagrangian measurements mitigated the problem of resolving velocity ambiguities, a problem which often limits the application of high-resolution pulse-coherent profilers. Turbulent dissipation rates were estimated from second-order structure functions of measured velocity. Drifters were advected towards, and subsequently trapped on, a convergent surface front which marked the edge of a freshwater plume. Measured dissipation rates increased as a drifter deployed within the plume approached the front. A drifter then propagated with and along the front as the fresh plume spread across the tidal flats. Near-surface turbulent dissipation measured at the front roughly matched a theoretical mean-shear-cubed relationship, whereas dissipation measured in the stratified plume behind the front was suppressed. After removal of estimates affected by surface waves, near-bed dissipation matched the velocity cubed relationship, although scatter was substantial. Dissipation rates appeared to be enhanced when the drifter propagated across small subtidal channels.

text: Lagrangian measurements of turbulent dissipation over a shallow tidal ﬂat from pulse coherent Acoustic Doppler Profilers We present high resolution (25 mm spatial, 8 Hz temporal) profiles of velocity measured over a shallow tidal flat using pulse-coherent Acoustic Doppler Profilers mounted on surface drifters. The use of Lagrangian measurements mitigated the problem of resolving velocity ambiguities, a problem which often limits the application of high-resolution pulse-coherent profilers. Turbulent dissipation rates were estimated from second-order structure functions of measured velocity. Drifters were advected towards, and subsequently trapped on, a convergent surface front which marked the edge of a freshwater plume. Measured dissipation rates increased as a drifter deployed within the plume approached the front. A drifter then propagated with and along the front as the fresh plume spread across the tidal flats. Near-surface turbulent dissipation measured at the front roughly matched a theoretical mean-shear-cubed relationship, whereas dissipation measured in the stratified plume behind the front was suppressed. After removal of estimates affected by surface waves, near-bed dissipation matched the velocity cubed relationship, although scatter was substantial. Dissipation rates appeared to be enhanced when the drifter propagated across small subtidal channels.

year: 2012

title: Te Ahi Kā

authors: Temara, Pou

subjects: Ahi kā

abstract: Ko te urutaumatua o tēnei tuhinga, ko te matapaki i te ahi kā. He aha tēnei tikanga? I pēhea i ara ake ai? He aha ōna mātāpono, ōna taipitopito? Koia te tūāpapa mō te tuhinga nei. Tuarua, ko te wānanga i te tikanga Māori me ōna rerenga pērā i te whakapapa. Ko te pātai ka puta i tēnei wāhanga o te wānanga ko tēnei nā, he aha te wāhi o te whakapapa ki te ahi kā? Ko te ngako o tēnei tuhinga ko te wetewete i te tikanga ahi kā kia whai tikanga ai te whakataukī nei, ‘ko te ahi kā te mana o te hapū ki te whenua’.

text: Te Ahi Kā Ko te urutaumatua o tēnei tuhinga, ko te matapaki i te ahi kā. He aha tēnei tikanga? I pēhea i ara ake ai? He aha ōna mātāpono, ōna taipitopito? Koia te tūāpapa mō te tuhinga nei. Tuarua, ko te wānanga i te tikanga Māori me ōna rerenga pērā i te whakapapa. Ko te pātai ka puta i tēnei wāhanga o te wānanga ko tēnei nā, he aha te wāhi o te whakapapa ki te ahi kā? Ko te ngako o tēnei tuhinga ko te wetewete i te tikanga ahi kā kia whai tikanga ai te whakataukī nei, ‘ko te ahi kā te mana o te hapū ki te whenua’.

year: 2012-05