32,351 research outputs found
Electrodeposition of nanocrystalline nickel–cobalt binary alloy coatings: a review
No full textThe history of Ni–Co alloy deposits is summarised and recent developments are highlighted. Electrodeposition of nanocrystalline Ni–Co binary alloys and, briefly, Co–Ni–P ternary coatings is considered, including chemical composition, phase composition and crystalline nature. Nanostructure, morphology, physical and mechanical properties (including corrosion resistance) vs bath type and composition (including pH and electrolyte additives) and plating conditions, including current density, temperature and agitation are summarised. Applications range from wear and corrosion resistant coatings, particularly as a hard chromium replacement to speciality hydrogen evolution electrodes in water electrolysis. Following this extensive review, future research needs are briefly listed
Electrodeposition of nanocrystalline nickel and cobalt coatings
No full textThe importance of nanostructured deposits and methods for achieving them are considered. The scope for nickel and cobalt nanocrystalline single metal deposits is summarised and developments in the last decade are highlighted. In each case, chemical composition, phase composition and crystal structure are included. Nanostructure, physical and mechanical properties (including corrosion resistance) v. bath type and composition (including pH and electrolyte additives) together with plating conditions, including current density, temperature and agitation are summarised. While the majority of published studies have featured nickel, the more expensive cobalt has also been considered due to its better corrosion and high temperature oxidation resistance in some environments. An overall comparison between the two metals is made. The major applications of nanocrystalline nickel have been in wear and corrosion resistant coatings, particularly as a hard chromium replacement, but speciality emerging uses include catalytic electrode surfaces in water electrolysis. Future research needs are briefly liste
The electrodeposition and characterisation of low-friction and wear-resistant Co-Ni-P coatings
No full textA new Co-Ni-P coating having superior properties to hard chrome coatings for anti-wear applications has been developed by combining the precipitation hardening of Ni-P alloys with the lubricity of cobalt-rich Co-Ni coatings. The evolution of composition andmicrostructure, hardness, thermal stability and tribological properties have been investigated. The local pH value near the cathode played an important role in the change of the microstructure from nanocrystalline to amorphous along the growth direction as the phosphorous content increased from 7 at.% to 26 at.%. The highest microhardness (980 HV) and the lowest wear rate (one order of magnitude lower than that of hard chrome coatings under the same dry sliding conditions) were achieved by annealing the coatings at 400 °C facilitating precipitation hardening. Furthermore, the coefficients of friction of both the as-deposited Co-Ni-P coating and the heat-treated sampleswere approximately 0.3, only half of that of hard chrome coatings. The wear rates of Co-Ni-P coatings annealed up to 400 °C are 4–7 times lower compared to that of hard chrome. The roll-like debris found on the worn surfaces of the coating annealed at 500 °C were oriented perpendicularly to the sliding direction. Such part might be related to the slightly reduced coefficient of friction in the stable stag
The role of a tribofilm and wear debris in the tribological behaviour of nanocrystalline Ni–Co electrodeposits
No full textThe tribofilm and debris generated from wear tests acting as a third body can make important contributions to a tribo-system. The effect of tribofilm on sliding friction and wear depends strongly on the applied sliding conditions, and it is still lack of understanding due to insufficient experimental studies. In the present research, the electrodeposited nanocrystalline Ni–Co coatings with different cobalt content were prepared. The worn surfaces as well as the wear debris were characterised by surface analysis techniques after dry sliding tests against a stainless steel ball. The tribofilms containing iron from the counterparts were formed on the worn surface of the coatings (less than 60 at.% Co), which exhibited high coefficients of friction and wear rates. No tribofilm or iron transfer from the pin was found on the Co-rich coatings (more than 70 at.% Co) but a dramatic friction reduction of 50% and improved wear resistance were experienced. The wear debris contains a mixture of face-centred cubic (fcc) metallic phase and fcc oxidised phase, irrespective of the coating composition. The oxidised debris cannot form an efficient lubricative film to promote separation of the sliding surfaces
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Effects of additives on microstructure and properties of electrodeposited nanocrystalline Ni–Co alloy coatings of high cobalt content
No full textSaccharin and 2-butin-1,4-diol (BD) were investigated as electrolyte additives to electrodeposit high quality nickel-cobalt alloys (78¡2 at-%Co) as a protective surface coating on steel for tribological applications. The additives facilitated controlled electrodeposition of nanocrystalline coatings. The properties of the coatings investigated included surface morphology, grain size, crystalline texture and hardness. Tribological performance against a steel counterpart was studied via a reciprocating ball on disk. The coating microstrain could be manipulated from tensile to compressive and texture could be modified from (10 -10) for hexagonal close packed (hcp) structure to (0002)hcp/(111) for face centred cubic (fcc) structure. The inhibition effect of absorbed species on electrodeposited nanocrystalline coatings is explained via analysis of grain size and texture. The coating from the bath with an optimised additive content had a high hardness (500 HV) due to its reduced grain size (11¡1 nm) and improved tribological properties due to a high proportion of hcp structur
Exploring Emptiness: An Investigation of MA and MU in My Sonic Composition Practice
No full textThe commentary investigates Japanese aesthetics of space, silence and emptiness - ma and mu - that informed my compositional practice during the research period 2012 - 2015. The portfolio comprises text compositions and sound installations in which forms of micro events and sustained events are employed. Throughout, the emphasis is on my personal engagement with, and manifestation of emptiness that concerns a particular model of listening and perception.
Chapter 1 discusses six primary research areas: ma and mu, material, text, form, listening and perception. Firstly, I introduce ma and mu by examining noh culture and Zeami's teaching of senu hima (where there is no-action) in the context of my personal approaches to music. The following subjects are then used to contextualise my PhD practice by means of examples from various composers and visual artists. Here, these particular and enigmatic concepts are explored through Japanese art as well as Western contemporary works by Alvin Lucier, Eliane Radigue and those of the Wandelweiser collective.
Part 2 provides contextual commentaries on selected compositions from the portfolio that mostly articulate my aesthetics in relation to the topics covered in Chapter 1. koso koso addresses my methodologies to investigate the essence of senu hima, followed by treow that discusses my approach to materials and the importance of space. I move on to grade two and grade two extended in order to examine text scores, and then, look into Espèces d'espaces 03 and 04 as examples of musical forms that I employ.
Finally, listening and perception are investigated through the compositions gnome and con.de.structuring. Throughout, I describe how my works explore emptiness as a result of my particular emphasis on listening over composing
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
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