Thesis (M.E.)--University of Canterbury, 2005. / Typescript (photocopy). "August 2005." Includes bibliographical references (p. 107-115). Also available via the World Wide Web.

The present thesis focuses on characterisation of microstructure and the resulting mechanical and tribological properties of CVD and PVD coatings used in metal cutting applications. These thin and hard coatings are designed to improve the tribological performance of cutting tools which in metal cutting operations may result in improved cutting performance, lower energy consumption, lower production costs and lower impact on the environment.  In order to increase the understanding of the tribological behaviour of the coating systems a number of friction and wear tests have been performed and evaluated by post-test microscopy and surface analysis. Much of the work has focused on coating cohesive and adhesive strength, surface fatigue resistance, abrasive wear resistance and friction and wear behaviour under sliding contact and metal cutting conditions. The results show that the CVD deposition of accurate crystallographic phases, e.g. α-Al2O3 rather than κ-Al2O3, textures and multilayer structures can increase the wear resistance of Al2O3. However, the characteristics of the interfaces, e.g. topography as well as interfacial porosity, have a strong impact on coating adhesion and consequently on the resulting properties.  Through the deposition of well designed bonding and template layer structures the above problems may be eliminated. Also, the presence of macro-particles in PVD coatings may have a significant impact on the interfacial adhesive strength, increasing the tendency to coating spalling and lowering the surface fatigue resistance, as well as increasing the friction in sliding contacts. Finally, the CVD-Al2O3 coating topography influences the contact conditions in sliding as well as in metal cutting. In summary, the work illuminates the importance of understanding the relationships between deposition process parameters, composition and microstructure, resulting properties and tribological performance of CVD and PVD coatings and how this knowledge can be used to develop the coating materials of tomorrow.

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Weapons of the late Shang (c.1200-1050 B.C.), characterised by their frequent discovery and various forms and materials, have often been dogmatically deciphered as either symbolic signifiers or representing military equipment. Adopting an object biographical approach, the main objective of this thesis is to employ the corpus of weapons to explore the martial facet of Shang society. Multiple strands of evidence have been compiled for the investigation: two datasets composed of over 200 complete tombs with their assemblages from the Anyang site of the late Shang, finds from non-burial contexts, the British Museum bronze weaponry collection, and contemporaneous texts. Using for the first time both statistical tools and metalwork wear analysis, this thesis challenges our understanding of the weapons of the Shang from their classification in archaeological reports to their functions and roles in society. The diverse types and materials of weapons and their multifaceted functions also shed light on interactions between objects and human beings.

The purpose of this study is to explore gender-issues by the means of extreme contrasts in functionality. The motivation behind the work comes from the structural objectification of women that is maintained through fashion and social media, and how this is an issue that mainly regards women. By morphing extreme contrasts in dress, by the means of male coded work wear, and female coded shape wear, this work explores gender related norms, ideals and statuses. Through this work, shape was decided through try-outs with garments and/or their components, with a research that was based on today’s ideals, and social media trends. Lines in garments became increasingly more important during the process, and the components of garments in the different categories too. In the result the importance of colour, material and shape regarding gender-issues in dress is highlighted, since they often convey a gender coded expression. To disrupt this inherit gender, the result demonstrates how these components can be mixed. Breaking down status in gender attributes could be used to create a more equal sphere in fashion.

In sliding bearing wear is a very common problem and can be affected by several factors. The wear in a bearing can lead to total failure of the component and lower the lifetime. In a sliding bearing used in a machine in the pulp and paper industry large wear has been detected, but no clear evidence of what the wear depends on. The environment in the machine is strong alkaline (pH 14), a solution of white liquor and lime mud. The penetration of this solution into the bearing might lead to increased wear. A wear study and test were done to see if a better material choice could reduce the wear. In this project an investigation of the wear for seven different bearing materials was done. Two cobalt-based alloy Stellite 6 and Stellite 12, two different precipitation hardened martensitic stainless steel with different number of alloying elements, 17-4PH and Endotec 04. The different metals were welded on the pin with a minimum of 3mm. The other material was three different PEEK polymer composites. PEEK HPV reinforced with carbon fiber, PTFE and graphite. PEEK CA30 with carbon fibers and PEEK GF30 with glass fiber. The method used for the wear test was grinding machine that was reconstructed to a pin-on-disc tribology test. The tests were executed in room temperature with sliding speed of 150rpm and duration of 20 minutes. The metals were tested with the solution of white liquor mixed with lime mud, at two different loading conditions of 300N and 550N. The polymer composites were tested at the load of 300N but with different solution present, white liquor mixed with lime mud and with water. All the pins were sliding against a disc of austenitic stainless steel. Equipment used to investigate the wear mechanisms was a scanning electron microscope. The wear rate was measured by weighing of the pin before and after each test. How the material was affecting the roughness of the austenitic steel countersurface was done with the profilometer. The results of this work showed that both Stellite 6 and Stellite 12 was almost wear resistance in the condition similar to the bearing. Endotec 04 also showed low wear and 17-4PH had the highest of the metals. The dominant wear mechanism seemed to be different severity of adhesive wear. The polymer composite showed all higher wear than the metals, the reason to the high wear rate was harder to decide. It might be a combination between adhesive wear, pulverization of fibers, adsorption of calcium carbonate and matrix/fiber interfacial removal. The alkaline liquid was also believed to increase the wear of the polymer and adhere to some of the metals. The metals seemed to increase the roughness of the countersurface, but the polymers seemed to have more of a polishing effect.

No description available.

Historical keyboard instruments have for many years been a valuable source of information regarding historical building techniques and performance practices. However, almost no attention has been paid to the evidence of wear present on these instruments. This physical trace documents the form in which an instrument has been used throughout time. Of particular interest is the evidence of wear found on the surface of the keys. An analysis of this physical trace might provide insight into a number of aspects which have defined the manner in which performers have approached their instruments. A survey of historical keyboard playing practices will help to visualise in a broader form the mechanical reasons behind the impact of the fingers on the surface of the key. However, it is important to consider that while the process behind the appearance of a trace of wear is primarily of a mechanical nature, the fact that both instrument and the performer‘s body are cultural objects calls for an examination of a number of issues which seem to influence the form in which the mechanical action is applied. Two important routes are thus taken in this study before the trace of wear is examined. First, a number of uses of the hand and the fingers seem to have originated in the interaction between the performer and the earliest keyboard designs that the medieval organ displayed. An analysis of these uses served as a starting point for the study here of a number of playing practices which remained in currency for long periods. Second, the forms in which the instrument is built and the body operates at it are the result of the socio-cultural and historico-geographical conditions in which both are submerged. Particular attention is thus given here to the potential effect the performer‘s socio-cultural background had on the mechanical action he or she was to use when performing. An experimental clavichord, whose tops were designed to reveal patterns of abrasion more rapidly than those commonly used to cover the keys, was used to aid in an examination of the particular effect of the fingers on the surface of the key. In this form, specific information concerning the various stages of the abrasion caused by the finger‘s contact with the surface of the keys could be gathered. The worn keys of this instrument also provided a much needed reference point to which historical traces of wear could be compared. This helped to establish a number of potential finger actions that might have been responsible for the traces of wear on some historical instruments. A reconstruction of J.S. Bach‘s playing approach was adopted for playing on the experimental clavichord. At the same time, a number of socio-cultural aspects which might have defined Bach‘s approach to the instrument were explored. In this form, a broader picture could be offered which is not limited to an understanding of the most likely mechanical causes behind the origin of the trace of wear.

Orientador: Vicente Afonso Ventrella / Resumo: Dentre os diversos aços ferramenta disponíveis atualmente, encontra-se o aço VP 100, aço ferramenta de estrutura bainítica empregado no setor de fabricação de moldes e matrizes. A literatura traz diversos estudos acerca desse aço frente à processos de usinagem. Entretanto, poucos estudos tratam do comportamento desse aço frente a utilização, direta ou indireta, de processos de soldagem. Desse modo, esse trabalho analisou a influência na estrutura e, nas propriedades mecânicas (dureza e taxa de desgaste) superficiais, do aço VP 100 quando submetido a um processo de tratamento térmico superficial. O processo de tratamento térmico superficial foi realizado através da execução de sucessivos cordões de solda, autógenos, na superfície do material, por meio de um sistema de laser de estado sólido Nd:YAG na condição pulsado. O aço VP 100 foi inicialmente investigado quanto a presença de isotropia em sua estrutura, visando excluir a direção adotada para tratamento térmico como fator influenciador nos resultados. Com uma estrutura visualmente semelhante em todas as direções e, com valores de dureza médios muito próximos entre direções, a direção adotada foi excluída como fator de influência no processo. Em seguida, realizou-se cordões de solda, autógenos, em seis condições distintas (SG, AR, N, N1, N2 e N3), analisados posteriormente através de ensaios de microdureza Vickers, para determinação da melhor condição para execução do tratamento térmico. As condições N1, N2 e N3 (todas com u... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Among the steels currently available, is steel VP 100, a tool steel used in the mold and matrix manufacturing sector. There are many research on the machining process forward in this steel. However, few studies deal with work from this steel versus a direct or indirect use of welding processes. In this way, this work analyzed the influence on the structure and, under the mechanical conditions (hardness and wear rate), of the VP 100 steel when subjected to a superficial thermal treatment process. The surface heat treatment process was performed through the execution of successive weld beads, autogenous, on the surface of the material by means of a Nd: YAG solid state laser system in pulsed condition. The VP 100 steel was first investigated for the presence of isotropy in its structure, aiming the analysis if the direction took adopted for the heat treatment as an influencing factor in the results. With a visually similar structure in all directions and, with the average hardness values very close between the directions, the adopted direction was excluded as a factor of influence in the process. In the next step, weld beads, autogenous, were produced in six different condition (SG, AR, N1, N2 and N3), posterior analyzed by means of Vickers microhardness tests to determine the best condition for heat treatment. The N1, N2 and N3 conditions (all using nitrogen gas) presented the best hardness results (superficially and in the depth range of 0.30 mm), being chosen for the executio... (Complete abstract click electronic access below) / Doutor

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No. of bitstreams: 1 crespo_gs_dr_ilha.pdf: 4967768 bytes, checksum: c8e5785db6eaf0a8ac2b750452764960 (MD5) Previous issue date: 2018-08-03 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Dentre os diversos aços ferramenta disponíveis atualmente, encontra-se o aço VP 100, aço ferramenta de estrutura bainítica empregado no setor de fabricação de moldes e matrizes. A literatura traz diversos estudos acerca desse aço frente à processos de usinagem. Entretanto, poucos estudos tratam do comportamento desse aço frente a utilização, direta ou indireta, de processos de soldagem. Desse modo, esse trabalho analisou a influência na estrutura e, nas propriedades mecânicas (dureza e taxa de desgaste) superficiais, do aço VP 100 quando submetido a um processo de tratamento térmico superficial. O processo de tratamento térmico superficial foi realizado através da execução de sucessivos cordões de solda, autógenos, na superfície do material, por meio de um sistema de laser de estado sólido Nd:YAG na condição pulsado. O aço VP 100 foi inicialmente investigado quanto a presença de isotropia em sua estrutura, visando excluir a direção adotada para tratamento térmico como fator influenciador nos resultados. Com uma estrutura visualmente semelhante em todas as direções e, com valores de dureza médios muito próximos entre direções, a direção adotada foi excluída como fator de influência no processo. Em seguida, realizou-se cordões de solda, autógenos, em seis condições distintas (SG, AR, N, N1, N2 e N3), analisados posteriormente através de ensaios de microdureza Vickers, para determinação da melhor condição para execução do tratamento térmico. As condições N1, N2 e N3 (todas com utilização de gás nitrogênio), apresentaram os melhores resultados de dureza (superficialmente e na faixa de profundidade de 0,30 mm), sendo escolhidas para a execução do tratamento térmico. Os corpos de prova tratados termicamente foram analisados através de difratogramas de raios-x e réplica por extração de carbono. Em nenhuma das duas análises houve a detecção da formação de nitretos no metal pós-tratamento. Ainda acerca dos difratogramas de raios-x, os dados obtidos mostraram a mudança da estrutura do material, de bainítica para martensítica, e a redução do tamanho dos cristalitos nas três condições. Os ensaios de taxa de desgaste mostraram melhores resultados para as condições de maior dureza, com melhores resultados na condição N3. Por fim, a condição N3 foi estipulada como a melhor condição, dentre as analisadas, para realização de tratamento térmico superficial no aço VP 100, apresentando além de uma elevação na dureza, uma baixa taxa de desgaste, fatores atribuídos à formação de uma estrutura martensítica, redução do tamanho dos cristalitos e intersticialização de nitrogênio no metal pós-tratamento térmico. / Among the steels currently available, is steel VP 100, a tool steel used in the mold and matrix manufacturing sector. There are many research on the machining process forward in this steel. However, few studies deal with work from this steel versus a direct or indirect use of welding processes. In this way, this work analyzed the influence on the structure and, under the mechanical conditions (hardness and wear rate), of the VP 100 steel when subjected to a superficial thermal treatment process. The surface heat treatment process was performed through the execution of successive weld beads, autogenous, on the surface of the material by means of a Nd: YAG solid state laser system in pulsed condition. The VP 100 steel was first investigated for the presence of isotropy in its structure, aiming the analysis if the direction took adopted for the heat treatment as an influencing factor in the results. With a visually similar structure in all directions and, with the average hardness values very close between the directions, the adopted direction was excluded as a factor of influence in the process. In the next step, weld beads, autogenous, were produced in six different condition (SG, AR, N1, N2 and N3), posterior analyzed by means of Vickers microhardness tests to determine the best condition for heat treatment. The N1, N2 and N3 conditions (all using nitrogen gas) presented the best hardness results (superficially and in the depth range of 0.30 mm), being chosen for the execution of the thermal treatment. The thermally treated specimens were analyzed by x-ray diffraction and replication by carbon extraction. In none of the two analyzes was the detection of nitride formation in the metal after treatment. Still about the x-ray diffractograms, the data obtained showed the change in the structure of the material, from bainitic to martensitic, and the reduction of the size of the crystallites in the three conditions. The wear rate tests showed better results for the best hardness conditions, with better results in the N3 condition. Finally, the condition N3 was stipulated as the best parameters, among the analyzed ones, for the accomplishment of superficial thermal treatment in the steel VP 100, presenting a rise in the hardness besides a low rate of wear, factors attributed to the formation of a martensitic structure, crystallite size reduction and nitrogen interstitialization in the post-heat treatment metal. / CAPES:DS 1517021