Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains vii, 64 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 62-64).

Thesis (Ph. D.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xix, 233 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 223-233).

No description available.

Thesis (M.S.)--University of Michigan, 1982.

Th. doct.-ing.--Sci des matér.--Nancy--I.N.P.L., 1984.

No description available.

Ventaneiras são componentes críticos para a operação de altos fornos, soprando ar quente para o interior dos mesmos. São peças de cobre refrigeradas a água para resistir ao ambiente de trabalho com temperaturas extremamente elevadas e geralmente apresentam revestimentos superficiais para aumento de resistência contra abrasão/corrosão. O presente trabalho tem como objetivo estudar o processo de revestimento de cobre e de liga à base de níquel por alumínio via PCDC a fim de entender os efeitos das variáveis de processo nas características do revestimento formado e obter camadas de revestimento equivalentes ao que vem sendo utilizado recentemente com bons resultados em operação na indústria. Uma série de ensaios são preparados utilizando-se os substratos de cobre e liga Inconel 625 e são variados alguns parâmetros de processo como a liga máster utilizada (Al e/ou liga Fe-Al), o sal haleto ativador do processo (NH4Cl ou NaF), condição in ou out of pack, proporção entre alumina e liga máster, temperatura e tempo de processo. É realizada a caracterização dos substratos previamente e após passar pelo processo de aluminização. Também é feita uma análise de amostra tomada como referência revestida por empresa externa especializada em aluminização via PCDC, além da caracterização de todas as amostras ensaiadas. A caracterização das amostras consiste na análise microestrutural identificando as fases presentes nos revestimentos formados, morfologia das camadas, espessuras, e propriedade de dureza. As análises são realizadas através de microscópio ótico, MEV, técnicas de EDS e difração de raios X e microdurômetro. Ao final das análises, é possível identificar conjuntos de parâmetros de processo que conduzem à formação de revestimento similar ao que está sendo utilizado na indústria. Além disso, é possível entender o efeito das variáveis de processo nas características das camadas formadas sobre os substratos. / Tuyeres are critical components for blast furnace operation, blowing hot air to the interior of the furnace. They are made of copper and are water cooled in order to resist extremely high operation temperatures. Aiming to improve reliability and lifetime of the tuyeres, different types of coatings (metallic hard facings, ceramic and diffusion coatings) have been developed over the years to enhance surface resistance of the pieces. The objective of the present work is to study the process of coating copper and nickel alloy by aluminum via pack cementation diffusion coating (PCDC) in order to understand the effect of each process parameter in the features of the coating formed and to obtain coating layers similar to what has been used with good results in the industry. Several experiments are prepared for coating the substrates made of copper and Inconel 625 and some parameters are varied such as the master alloy (Al and/or Fe-Al), the activator salt (NH4Cl or NaF), the condition in or out of pack, the alumina/master alloy ratio, temperature and time of the process. It is performed analysis of the substrates previous and after the aluminization process. A sample coated in an external company specialized in aluminization process is also analyzed and taken as a reference. In addition, all the experiment samples with different process conditions are studied. The analysis consist in microstructural evaluation identifying phases formed, thickness of the coating layers and hardness measurements and are performed with the use of optical microscope, SEM, EDS techniques, X-ray diffraction technique and micro durometer. At the end of the analysis, it is possible to identify sets of process parameters that can lead to the formation of coating layers similar to what has been used with success in the industry. Furthermore, it is possible to understand the effect of the process variables in the features of the coating layers.

Thesis (M.S.)--Ohio University, March, 1994. / Title from PDF t.p.

Two aerospace superalloys, Inconel 718 and IMI 318, were machined with different grades of PVD (KC730 and KC732) and CVD (KC950) coated tools in order to evaluate their performance under various cutting conditions and to further investigate the effect of the machining conditions on surface finish and surface integrity of the work materials. A self-propelled rotary tool was also developed and used for machining under the finishing conditions. Tool wear, component forces and surface roughness were recorded and analysed during the machining trials. Study of the surface integrity involved physical as well as metallographic examination and analysis of the machined surfaces. The results of the machining trials show that the multi-layer (TiN/TiCN/TiN) PVD coated KC732 tools gave the best overall performance when machining both Inconel 718 and IMI 318, especially at lower feed conditions. Flank wear, excessive chipping, flaking of tool materials close to the cutting edge or on the rake face were the dominant failure modes when machining with the PVD coated tools while flank wear and notching were dominant when cutting with the CVD coated tools. These failure modes are associated with attrition, abrasion, diffusion and plastic deformation wear mechanisms acting individually or in combination during machining. The statistical regression analysis of the tool life data shows that wear of the PVD and CVD coated tools used for machining Inconel 718 was mainly affected by cutting speeds employed while cutting speed and feed rate exhibited similar influence on tool performance when machining IMI 318 with PVD coated tools. Tool life equations for each of the three coated grades when machining both superalloys under the cutting conditions investigated were derived. Severe plastic deformation and hardening of the machined surfaces occurred after machining both materials due to a combined action of increased component forces, thus increased stresses, and high temperature. Softening of the top surface layer when machining IMI 318 can be attributed to overaging of the titanium as a result of highly localised surface heating during machining. Tearing of the machined surfaces occurred when machining IMI 318 with the PVD coated tools, particularly with KC732 tools as a result of irregular flank wear and excessive chipping of KC732 tools. The self-propelled rotary tool (SPRT) incorporating K68 straight grade carbide exhibited superior wear-resistance when machining IMI 318 due to the absence of thermally related wear mechanisms caused by reduced temperature and the use of the entire edge of a round insert during rotary cutting. The minimal subsurface alterations (such as plastic deformation and hardness) when machining Inconel 718 and IMI 318 with the SPRT can also be attributed to lower cutting temperature with rotary action.

No description available.