title: Tribological properties of thermally sprayed TiAl-Al₂O₃ composite coating

authors: Salman, Asma Siddiq

subjects: engineering

abstract: The use of thermal spray coatings provides protection to the surfaces operating in severe environments. The main goal of the current work is to investigate the possibility of using a high velocity oxy fuel (HVOF) thermally sprayed wear resistant TiAl/Al2O3 coating on tool steel (H13) which is used for making dies for aluminium high pressure die casting. A feedstock of TiAl/Al2O3 composite powder was produced from a mixture of Al and TiO2 powders by high energy mechanical milling, followed by a thermal reaction process. The feedstock was then thermally sprayed using a high velocity oxy-fuel (HVOF) technique onto H13 steel substrates to produce a composite coating. The present study describes and compares the tribological properties such as friction and sliding wear rate of the coating both at room and high temperature (700°C). The results showed that the composite coating has lower wear rate at high temperature (700°C) than the uncoated H13 sample. At Room temperature without using lubricant there is no much significant difference between the wear rate of the coated and uncoated samples. The experimental results showed that the composite coating has great potential for high temperature application due to its lower wear rate at high temperature in comparison with the uncoated sample at the same temperature. The composite coating was characterized using scanning electron microscopy (SEM), optical microscopy and X-ray diffractometry (XRD). This paper reports the experimental observations and discusses the wear resistance performance of the coatings at room and high temperatures.

text: Tribological properties of thermally sprayed TiAl-Al₂O₃ composite coating The use of thermal spray coatings provides protection to the surfaces operating in severe environments. The main goal of the current work is to investigate the possibility of using a high velocity oxy fuel (HVOF) thermally sprayed wear resistant TiAl/Al2O3 coating on tool steel (H13) which is used for making dies for aluminium high pressure die casting. A feedstock of TiAl/Al2O3 composite powder was produced from a mixture of Al and TiO2 powders by high energy mechanical milling, followed by a thermal reaction process. The feedstock was then thermally sprayed using a high velocity oxy-fuel (HVOF) technique onto H13 steel substrates to produce a composite coating. The present study describes and compares the tribological properties such as friction and sliding wear rate of the coating both at room and high temperature (700°C). The results showed that the composite coating has lower wear rate at high temperature (700°C) than the uncoated H13 sample. At Room temperature without using lubricant there is no much significant difference between the wear rate of the coated and uncoated samples. The experimental results showed that the composite coating has great potential for high temperature application due to its lower wear rate at high temperature in comparison with the uncoated sample at the same temperature. The composite coating was characterized using scanning electron microscopy (SEM), optical microscopy and X-ray diffractometry (XRD). This paper reports the experimental observations and discusses the wear resistance performance of the coatings at room and high temperatures.

year: 2009

title: How can we know what we think until we see what we said? A citation and citation context analysis of Karl Wieck's , 'The Social Psychology of Organizing'

authors: Anderson, Marc Howard

subjects: Karl Weick

abstract: A substantial portion of Karl Weick’s influence on organization studies is based upon his classic book The Social Psychology of Organizing (abbreviated as Organizing). A citation analysis shows the magnitude of this influence compared to five other organization studies classics, and reveals that Organizing continues to be highly cited. A citation context analysis (i.e. content analysis) of all citations to Weick (1979) in three top organization studies journals (Academy of Management Review, Administrative Science Quarterly, and Organization Studies) shows that 12 concepts account for 67.6% of citations to Organizing, but that the book is cited for a remarkable diversity of additional content as well. Furthermore, a consideration of differences between the concepts cited in the US journals versus Organization Studies reveals several regional differences. Finally, very few citations are critical of Organizing or involve empirical tests. These results hold a variety of implications for future research.

text: How can we know what we think until we see what we said? A citation and citation context analysis of Karl Wieck's , 'The Social Psychology of Organizing' A substantial portion of Karl Weick’s influence on organization studies is based upon his classic book The Social Psychology of Organizing (abbreviated as Organizing). A citation analysis shows the magnitude of this influence compared to five other organization studies classics, and reveals that Organizing continues to be highly cited. A citation context analysis (i.e. content analysis) of all citations to Weick (1979) in three top organization studies journals (Academy of Management Review, Administrative Science Quarterly, and Organization Studies) shows that 12 concepts account for 67.6% of citations to Organizing, but that the book is cited for a remarkable diversity of additional content as well. Furthermore, a consideration of differences between the concepts cited in the US journals versus Organization Studies reveals several regional differences. Finally, very few citations are critical of Organizing or involve empirical tests. These results hold a variety of implications for future research.

year: 2006

title: Prototype theory and the concept of taonga: Implications for Treaty-related issues such as the display and conservation of taonga Māori

authors: Hedley, Rangiiria

subjects: Taonga Māori

abstract: This paper examines, in the context of prototype theory, issues and problems associated with the concept of taonga, the specific aim being to provide an approach that could assist those who are concerned with the interpretation of Article 2 of the Treaty of Waitangi and Treaty-related issues such as the appropriate display and conservation of taonga Māori.

text: Prototype theory and the concept of taonga: Implications for Treaty-related issues such as the display and conservation of taonga Māori This paper examines, in the context of prototype theory, issues and problems associated with the concept of taonga, the specific aim being to provide an approach that could assist those who are concerned with the interpretation of Article 2 of the Treaty of Waitangi and Treaty-related issues such as the appropriate display and conservation of taonga Māori.

year: 2004-02