title: The performance of thermally sprayed titanium based composite coatings in molten aluminium

authors: Salman, Asma Siddiq

subjects: mechanical milling

abstract: The service life of die and tool steels in contact with molten aluminium is important in the aluminium processing industry. This article describes an investigation of the efficiency of thermally sprayed Ti(Al,O)/Al₂O₃ and TiAl(O)/Al₂O₃ composite coatings in resisting aluminium soldering on H13 tool steel. The powder feedstocks for making the composite coatings were produced by high energy mechanical milling of a mixture of Al and TiO₂ powders using different molar ratios followed by a thermal reaction process. The feedstocks were then thermally sprayed using a high velocity oxygen fuel (HVOF) technique onto an H13 steel substrate to produce composite coatings. The performance of the coatings was assessed in terms of Al soldering and liquid metal corrosion resistance after immersing in molten aluminium at a temperature of 700 ± 10 °C. The results of this study showed that composite coatings have a potential to act as a physical barrier to prevent aluminium attack on H13 tool steel. The nature of Al attack on H13 tool steel changed from generalised to more localised attack with the thermally sprayed coating. A Ti(Al,O)/Al₂O₃ composite coating was not attacked by molten aluminium, however localised attack on a H13 tool steel substrate was found to be caused by molten metal penetration through defects in the coating. Composite coating TiAl(O)/Al₂O₃ was attacked by molten aluminium resulting in dissolution of the coating. Composite coatings showed significantly lower dissolution in molten aluminium compared with the uncoated H13 steel. A Ti(Al,O)/Al₂O₃ composite coating was found to be a more effective protective coating than a TiAl(O)/Al₂O₃ composite coating due its greater resistance to molten aluminium attack.

text: The performance of thermally sprayed titanium based composite coatings in molten aluminium The service life of die and tool steels in contact with molten aluminium is important in the aluminium processing industry. This article describes an investigation of the efficiency of thermally sprayed Ti(Al,O)/Al₂O₃ and TiAl(O)/Al₂O₃ composite coatings in resisting aluminium soldering on H13 tool steel. The powder feedstocks for making the composite coatings were produced by high energy mechanical milling of a mixture of Al and TiO₂ powders using different molar ratios followed by a thermal reaction process. The feedstocks were then thermally sprayed using a high velocity oxygen fuel (HVOF) technique onto an H13 steel substrate to produce composite coatings. The performance of the coatings was assessed in terms of Al soldering and liquid metal corrosion resistance after immersing in molten aluminium at a temperature of 700 ± 10 °C. The results of this study showed that composite coatings have a potential to act as a physical barrier to prevent aluminium attack on H13 tool steel. The nature of Al attack on H13 tool steel changed from generalised to more localised attack with the thermally sprayed coating. A Ti(Al,O)/Al₂O₃ composite coating was not attacked by molten aluminium, however localised attack on a H13 tool steel substrate was found to be caused by molten metal penetration through defects in the coating. Composite coating TiAl(O)/Al₂O₃ was attacked by molten aluminium resulting in dissolution of the coating. Composite coatings showed significantly lower dissolution in molten aluminium compared with the uncoated H13 steel. A Ti(Al,O)/Al₂O₃ composite coating was found to be a more effective protective coating than a TiAl(O)/Al₂O₃ composite coating due its greater resistance to molten aluminium attack.

year: 2011

title: Cross-Needle analog meter to monitor charge time for Lithium-Ion single cell

authors: Mohri, Hiroshi

subjects: Cross-Needle Meter

abstract: The Cross-Needle panel meter is an analog Standing wave ratio meter with a modified panel. It consists of two meters which are mirrored horizontally and 38mm apart. One needle indicates the forward travelling wave on a trans-mission line, while the other needle indicates reverse travelling wave. A third scale, occupying the area swept by both needles, shows Standing Wave Ratio (SWR), essentially reflection coefficient, typically of an antenna connected to a radio transmitter. This thesis reports on an adaption of this idea. The first needle shows current into a battery, the second needle indicates the voltage of the battery. There is also a third scale using contour lines which show the amount of time left until the battery is fully charged.
The contour lines are calculated and drawn using analytic geometry by predetermining the rotation of the two needles. Hence the amount of time left for the battery to fully charge can be read by simply looking at where the the two needles cross and estimating from the closest contour line that displays charge time. The input current scale is expanded logarithmically with a wide range from 1mA to 10A. This scale also evenly spreads the contour lines from 10 minutes to 1 week as opposed to a linear current scale, which causes the contour lines beyond 6 hours to cluster making it difficult to observe the charge time at low charge current inputs. The battery voltage scale is offset to suit the battery voltage range.
The meter has been implemented using an embedded microprocessor on a PCB that mounts at the rear of the meter housing. The prototype has been calibrated for a single 18650 Lithium-Ion battery which is a popular scenario for portable equipment. This project provides a manufacturing solution for a low cost, low power, portable Lithium-ion battery monitor which can be easily replicated.

text: Cross-Needle analog meter to monitor charge time for Lithium-Ion single cell The Cross-Needle panel meter is an analog Standing wave ratio meter with a modified panel. It consists of two meters which are mirrored horizontally and 38mm apart. One needle indicates the forward travelling wave on a trans-mission line, while the other needle indicates reverse travelling wave. A third scale, occupying the area swept by both needles, shows Standing Wave Ratio (SWR), essentially reflection coefficient, typically of an antenna connected to a radio transmitter. This thesis reports on an adaption of this idea. The first needle shows current into a battery, the second needle indicates the voltage of the battery. There is also a third scale using contour lines which show the amount of time left until the battery is fully charged.
The contour lines are calculated and drawn using analytic geometry by predetermining the rotation of the two needles. Hence the amount of time left for the battery to fully charge can be read by simply looking at where the the two needles cross and estimating from the closest contour line that displays charge time. The input current scale is expanded logarithmically with a wide range from 1mA to 10A. This scale also evenly spreads the contour lines from 10 minutes to 1 week as opposed to a linear current scale, which causes the contour lines beyond 6 hours to cluster making it difficult to observe the charge time at low charge current inputs. The battery voltage scale is offset to suit the battery voltage range.
The meter has been implemented using an embedded microprocessor on a PCB that mounts at the rear of the meter housing. The prototype has been calibrated for a single 18650 Lithium-Ion battery which is a popular scenario for portable equipment. This project provides a manufacturing solution for a low cost, low power, portable Lithium-ion battery monitor which can be easily replicated.

year: 2018

title: Environmentalism for the environment's sake: Towards an understanding of the influence of the Māori worldview on Western environmental management perspectives in Aotearoa New Zealand through a lens of nature connectivity

authors: Jones, Haley

subjects: Nature connectedness

abstract: Individual perceptions of the natural world may be influenced by place, culture, and value systems. In exploring these perceptions through measures of environmental connectedness, this study considers the uniqueness of the socio-cultural systems of Aotearoa New Zealand in shaping individual environmental engagement. This research examines the implications of the inclusion of Māori values in environmental management policies dominated by Western environmental conceptualisations. Through semi-structured interviews of five participants who work in environmental fields in the Hamilton, Waikato Region of Aotearoa New Zealand, this research explores conceptualisations of identity and environmental discourses, interpretations of the Māori concept of kaitiakitanga and the Western concept of stewardship, career connectedness, and place attachment to Aotearoa New Zealand. Additionally, results from an online survey questionnaire of twelve respondents compare measures of connectedness to nature of respondents from California, United States of America, with those from the Waikato Region, Aotearoa New Zealand. Key findings highlight how anthropogenic worldviews can be unconscious, how understandings of cultural values may be a key factor of a strengthened environmental commitment, how expressions of Indigeneity are of value in the sciences, and how there is importance in the link between conservation values and the Māori worldview. This study exposes the importance of the implementation of improved training about, and inclusion of, Indigenous knowledge within environmental organisations in order to develop conscious awareness of how Indigenous information is being translated, applied, and respected.

text: Environmentalism for the environment's sake: Towards an understanding of the influence of the Māori worldview on Western environmental management perspectives in Aotearoa New Zealand through a lens of nature connectivity Individual perceptions of the natural world may be influenced by place, culture, and value systems. In exploring these perceptions through measures of environmental connectedness, this study considers the uniqueness of the socio-cultural systems of Aotearoa New Zealand in shaping individual environmental engagement. This research examines the implications of the inclusion of Māori values in environmental management policies dominated by Western environmental conceptualisations. Through semi-structured interviews of five participants who work in environmental fields in the Hamilton, Waikato Region of Aotearoa New Zealand, this research explores conceptualisations of identity and environmental discourses, interpretations of the Māori concept of kaitiakitanga and the Western concept of stewardship, career connectedness, and place attachment to Aotearoa New Zealand. Additionally, results from an online survey questionnaire of twelve respondents compare measures of connectedness to nature of respondents from California, United States of America, with those from the Waikato Region, Aotearoa New Zealand. Key findings highlight how anthropogenic worldviews can be unconscious, how understandings of cultural values may be a key factor of a strengthened environmental commitment, how expressions of Indigeneity are of value in the sciences, and how there is importance in the link between conservation values and the Māori worldview. This study exposes the importance of the implementation of improved training about, and inclusion of, Indigenous knowledge within environmental organisations in order to develop conscious awareness of how Indigenous information is being translated, applied, and respected.

year: 2022