title: Advancement in the pressureless sintering of CP titanium using high-frequency induction heating

authors: Raynova, Stiliana (Stella) Rousseva

subjects: Science & Technology

abstract: High-frequency induction heating is applied as an alternative heating source for pressureless sintering of commercially pure Ti powders, aiming to intensify the sintering process. The effects of the process parameters on the properties of the sintered material are systematically studied. The initial powder compact density is the most influential parameter permitting sintered structures with highly porous to almost fully dense appearance. Short heating time combined with sintering to temperatures just above the β-transus resulted in a strong diffusion bonding between the Ti powder particles, and grain growth is observed at the former boundaries of the neighboring powder particles. The dimpled appearance of the fracture surface at those regions confirmed the strong metallic interparticle bonding. Tensile properties comparable to those of Ti-Grade 3 and Ti-Grade 4 are achieved, which also demonstrates the efficiency of the induction sintering process. A mechanism explaining the fast and efficient sintering is proposed. The process has the added advantage of minimizing the oxygen pickup.

text: Advancement in the pressureless sintering of CP titanium using high-frequency induction heating High-frequency induction heating is applied as an alternative heating source for pressureless sintering of commercially pure Ti powders, aiming to intensify the sintering process. The effects of the process parameters on the properties of the sintered material are systematically studied. The initial powder compact density is the most influential parameter permitting sintered structures with highly porous to almost fully dense appearance. Short heating time combined with sintering to temperatures just above the β-transus resulted in a strong diffusion bonding between the Ti powder particles, and grain growth is observed at the former boundaries of the neighboring powder particles. The dimpled appearance of the fracture surface at those regions confirmed the strong metallic interparticle bonding. Tensile properties comparable to those of Ti-Grade 3 and Ti-Grade 4 are achieved, which also demonstrates the efficiency of the induction sintering process. A mechanism explaining the fast and efficient sintering is proposed. The process has the added advantage of minimizing the oxygen pickup.

year: 2019

title: Effect of milling parameters on microstructure of Ti/Al composite powder produced by discus milling

authors: Raynova, Stiliana (Stella) Rousseva

subjects: TiAl

abstract: The motivation of this research is to develop a process for producing Ti/Al composite powders that enable synthesis of a single-phase TiAl intermetallic bulk material, which is then used as a target for physical vapour deposition (PVD) coating. This study reports the effects of milling time, amount of process control agent (PCA) added as well as the powder-to-medium ratio on the microstructure of the Ti/Al composite powder. Optical microscopy and scanning electron microscopy (SEM) were used to evaluate the level of mixing and the resulting powder particle size. X-ray diffraction analysis and differential thermal analysis were used for determining the phase constituents and the solid state reaction temperature of the as-milled powders.

text: Effect of milling parameters on microstructure of Ti/Al composite powder produced by discus milling The motivation of this research is to develop a process for producing Ti/Al composite powders that enable synthesis of a single-phase TiAl intermetallic bulk material, which is then used as a target for physical vapour deposition (PVD) coating. This study reports the effects of milling time, amount of process control agent (PCA) added as well as the powder-to-medium ratio on the microstructure of the Ti/Al composite powder. Optical microscopy and scanning electron microscopy (SEM) were used to evaluate the level of mixing and the resulting powder particle size. X-ray diffraction analysis and differential thermal analysis were used for determining the phase constituents and the solid state reaction temperature of the as-milled powders.

year: 2006

title: Kotahi anō te tupuna o te tangata Māori, ko Ranginui e tū nei, ko Papatūānuku e takato nei. Colonisation through Christianity

authors: Wallace, Ritane

subjects: Christianity

abstract: This thesis will look at the role that Christianity and the missionaries played in the colonisation of Māori during the 1800s. With discussion about the colonisation of Aotearoa, it is generally felt within the Christian community that the work of the missionaries and the Crown are separate and therefore the universal belief is that the missionaries are pardoned from the critique of their work here in Aotearoa. However, Christianity throughout history has always been a doorway for the British Empire to enter land that was not their own.
  
It is widely accepted from the viewpoint of Christianity that it holds a religious superiority over all Indigenous people and their religions dating back to Pope Alexander VI and the issuing of the Papal Bull “Inter Caetera” in 1493 to justify Christian European explorers’ claims on land and waterways they allegedly discovered. Christian hegemony shaped missionary views of the ‘other’ and justified the assimilation of Indigenous people into European Christianity. The negative effects of Christianity on Māori far outweigh the positives as mission stations up and down Aotearoa contributed heavily to the loss of language, religion, and land, the three foundational pillars of Māori and other Indigenous peoples around the world.
   
The thesis seeks to hold the missionaries and Christianity to account for its contribution to the colonisation and religious assimilation of Māori into a foreign and unrelated belief system.

text: Kotahi anō te tupuna o te tangata Māori, ko Ranginui e tū nei, ko Papatūānuku e takato nei. Colonisation through Christianity This thesis will look at the role that Christianity and the missionaries played in the colonisation of Māori during the 1800s. With discussion about the colonisation of Aotearoa, it is generally felt within the Christian community that the work of the missionaries and the Crown are separate and therefore the universal belief is that the missionaries are pardoned from the critique of their work here in Aotearoa. However, Christianity throughout history has always been a doorway for the British Empire to enter land that was not their own.
  
It is widely accepted from the viewpoint of Christianity that it holds a religious superiority over all Indigenous people and their religions dating back to Pope Alexander VI and the issuing of the Papal Bull “Inter Caetera” in 1493 to justify Christian European explorers’ claims on land and waterways they allegedly discovered. Christian hegemony shaped missionary views of the ‘other’ and justified the assimilation of Indigenous people into European Christianity. The negative effects of Christianity on Māori far outweigh the positives as mission stations up and down Aotearoa contributed heavily to the loss of language, religion, and land, the three foundational pillars of Māori and other Indigenous peoples around the world.
   
The thesis seeks to hold the missionaries and Christianity to account for its contribution to the colonisation and religious assimilation of Māori into a foreign and unrelated belief system.

year: 2021