title: Effects of PZT Reinforcement on the Properties of Fe-Based Composites Fabricated by Powder Metallurgy

authors: Alshammari, Yousef

abstract: Fe composites are highly valued for their unique mechanical and magnetic properties, making them essential in various industrial applications. This study represents the first reported attempt to combine PZT into an Fe matrix, aiming to develop novel Fe-PZT composites. The primary objective was to assess how the concentration of PZT influences the properties of these composites. The results show that increasing the PZT content in Fe-xPZT composites (where x = 1, 5, and 10 wt.%) reduces the relative sintered density. Microstructural analysis reveals that the composites with higher PZT levels contained numerous large, irregularly shaped pores due to a pronounced Kirkendall effect and limited densification. Furthermore, the evaporation of the volatile PbO compound was observed to affect the thermal stability of the PZT system, leading to reduced composite homogeneity. SEM analysis showed the formation of intermetallic compounds corresponding to Fe<inf>2</inf>Ti, FeTi, and FeZr<inf>2</inf>. Finally, an increase in PZT content tends to degrade the tensile and mechanical properties of the Fe-xPZT composites, though they still do not fail catastrophically. These preliminary findings prove the concept of the feasibility of producing Fe-PZT composites and set the basis for the optimization of their manufacturing process. This should eventually unlock the possibility of producing multifunctional materials.

text: Effects of PZT Reinforcement on the Properties of Fe-Based Composites Fabricated by Powder Metallurgy Fe composites are highly valued for their unique mechanical and magnetic properties, making them essential in various industrial applications. This study represents the first reported attempt to combine PZT into an Fe matrix, aiming to develop novel Fe-PZT composites. The primary objective was to assess how the concentration of PZT influences the properties of these composites. The results show that increasing the PZT content in Fe-xPZT composites (where x = 1, 5, and 10 wt.%) reduces the relative sintered density. Microstructural analysis reveals that the composites with higher PZT levels contained numerous large, irregularly shaped pores due to a pronounced Kirkendall effect and limited densification. Furthermore, the evaporation of the volatile PbO compound was observed to affect the thermal stability of the PZT system, leading to reduced composite homogeneity. SEM analysis showed the formation of intermetallic compounds corresponding to Fe<inf>2</inf>Ti, FeTi, and FeZr<inf>2</inf>. Finally, an increase in PZT content tends to degrade the tensile and mechanical properties of the Fe-xPZT composites, though they still do not fail catastrophically. These preliminary findings prove the concept of the feasibility of producing Fe-PZT composites and set the basis for the optimization of their manufacturing process. This should eventually unlock the possibility of producing multifunctional materials.

year: 2026-02-05

title: Supercapacitor assisted low dropout regulators (SCALDO) with reduced switches: A new approach to high efficiency VRM designs

authors: Kularatna, Nihal

subjects: VRM

abstract: Supercapacitor assisted low dropout (SCALDO) regulator is a new approach to develop high efficiency DC-DC converters with supercapacitors used for energy recovery. One limitation in these topologies is that in some configurations a large number of low-speed switches are required. If the SCALDO technique is adapted to build voltage regulator modules (VRM), it is necessary to reduce number of switches combined with a high current capable LDO. A new topology-variation with less number of switches can be achieved by reconfiguring the original SCALDO and adding an extra LDO to the circuit. The paper presents a summary of some preliminary work, and experimental results for a 2.5V proof of concept-prototype.

text: Supercapacitor assisted low dropout regulators (SCALDO) with reduced switches: A new approach to high efficiency VRM designs Supercapacitor assisted low dropout (SCALDO) regulator is a new approach to develop high efficiency DC-DC converters with supercapacitors used for energy recovery. One limitation in these topologies is that in some configurations a large number of low-speed switches are required. If the SCALDO technique is adapted to build voltage regulator modules (VRM), it is necessary to reduce number of switches combined with a high current capable LDO. A new topology-variation with less number of switches can be achieved by reconfiguring the original SCALDO and adding an extra LDO to the circuit. The paper presents a summary of some preliminary work, and experimental results for a 2.5V proof of concept-prototype.

year: 2013

title: 'Waitangi and indigenous rights: Revolution, law and legitimacy' by F.M. Brookfield

authors: Melbourne, Hirini

subjects: indigenous rights

abstract: 'Waitangi and Indigenous Rights: Revolution, Law and Legitimacy' book review by Hirini Melbourne.

text: 'Waitangi and indigenous rights: Revolution, law and legitimacy' by F.M. Brookfield 'Waitangi and Indigenous Rights: Revolution, Law and Legitimacy' book review by Hirini Melbourne.

year: 2000-10