Doctor of Philosophy (PhD) / This thesis aims to establish a sound scientific methodology for the effective and efficient polishing of thermally stable PCD composites (consisting of diamond and SiC) for cutting tools applications. The surface roughness of industrial PCD cutting tools, 0.06 μm Ra is currently achieved by mechanical polishing which is time consuming and costly because it takes about three hours to polish a 12.7 mm diameter PCD surface. An alternative technique, dynamic friction polishing (DFP) which utilizes the thermo-chemical reactions between the PCD surfaces and a catalytic metal disk rotating at high peripheral speed has been comprehensively investigated for highly efficient abrasive-free polishing of PCD composites. A special polishing machine was designed and manufactured in-house to carry out the DFP of PCD composites efficiently and in a controllable manner according to the requirements of DFP. The PCD polishing process and material removal mechanism were comprehensively investigated by using a combination of the various characterization techniques: optical microscopy, SEM and EDX, AFM, XRD, Raman spectroscopy, TEM, STEM and EELS, etc. A theoretical model was developed to predict temperature rise at the interface of the polishing disk and PCD asperities. On-line temperature measurements were carried out to determine subsurface temperatures for a range of polishing conditions. A method was also developed to extrapolate these measured temperatures to the PCD surface, which were compared with the theoretical results. The material removal mechanism was further explored by theoretical study of the interface reactions under these polishing conditions, with particular emphasis on temperature, contact with catalytic metals and polishing environment. Based on the experimental results and theoretical analyses, the material removal mechanism of dynamic friction polishing can be described as follows: conversion of diamond into non-diamond carbon takes place due to the frictional heating and the interaction of diamond with catalyst metal disk; then a part of the transformed material is detached from the PCD surface as it is weakly bonded; another part of the non-diamond carbon oxidizes and escapes as CO or CO2 gas and the rest diffuses into the metal disk. Meanwhile, another component of PCD, SiC also chemically reacted and transformed to amorphous silicon oxide/carbide, which is then mechanically or chemically removed. Finally an attempt was made to optimise the polishing process by investigating the effect of polishing parameters on material removal rate, surface characteristics and cracking /fracture of PCD to achieve the surface roughness requirement. It was found that combining dynamic friction polishing and mechanical abrasive polishing, a very high polishing rate and good quality surface could be obtained. The final surface roughness could be reduced to 50 nm Ra for two types of PCD specimens considered from pre-polishing value of 0.7 or 1.5 μm Ra. The polishing time required was 18 minutes, a ten fold reduction compared with the mechanical abrasive polishing currently used in industry.

Thesis (M.S.)--University of Michigan, 1984.

Thesis (M.S.)--University of Michigan, 1970.

Thesis (M.S.)--University of Toledo, 2009. / Typescript. "Submitted as partial fulfillments of the requirements for The Master of Science Degree in Mechanical Engineering." "A thesis entitled"--at head of title. Bibliography: leaves 104-110.

Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2005. / Steven Danyluk, Committee Chair ; Richard Salant, Committee Member ; Jeffrey Streator, Committee Member ; Michael Sacks, Committee Member ; Dennis Hess, Committee Member ; Leonard Borucki, Committee Member. Includes bibliographical references.

Thesis (M.S.)--University of Michigan, 1970. / eContent provider-neutral record in process. Description based on print version record.

Thesis (M.S.)--University of Michigan, 1984.

Thesis (Ph. D.)--Ohio State University, 2006. / Full text release at OhioLINK's ETD Center delayed at author's request

Made available in DSpace on 2014-06-11T19:28:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-02-27Bitstream added on 2014-06-13T20:58:46Z : No. of bitstreams: 1 ticianeli_mg_me_arafo.pdf: 1350387 bytes, checksum: ea0f36454c6c9f5c29da9a1476668be1 (MD5) / Este estudo avaliou a eficiência de diferentes técnicas de acabamento e polimento sobre duas cerâmicas odontológicas (Duceram Plus e Duceram LFC), em relação à rugosidade média superficial (Ra). Foram preparados quarenta discos com 8 mm de diâmetro e 4 mm de espessura para cada uma das cerâmicas utilizadas, seguindo-se as recomendações do fabricante. Previamente ao glazeamento, todos os corpos-de-prova foram regularizados com o auxílio de lixas d'água de diferentes granulações (240,360 e 600, nesta ordem), recebendo, em seguida, uma camada de glaze. Os 40 corpos-de-prova de cada cerâmica foram divididos em 8 grupos com 5 representantes em cada um, recebendo diferentes tratamentos de superfície: T1- glaze; T2- desgaste com ponta diamantada fina e ultrafina; T3- T2 + sistema de acabamento e polimento dental Sof-Lex (3 M); T4- T3 + pasta diamantada; T5- T2 + kit de polimento Super-Snap (Shofu); T6- T5 + pasta diamantada; T7- T2 mais borrachas abrasivas Viking (KG Sorensen); T8- T7 + pasta diamantada. Foram realizadas cinco mensurações de rugosidade média (Ra, em æm) em cada corpo-de-prova, utilizando-se um rugosímetro ajustado com cut-off de 0,25 mm, extensão de tracejamento de 1,25 mm e velocidade de medição de 0,10 mm/s. Os resultados foram analisados estatisticamente pelos testes ANOVA e Tukey, com nível de significância de 5%. Os melhores tratamentos para ambas as cerâmicas avaliadas foram T3, T4, T5 e T6, apresentando semelhança estatística entre si; O glazeamento (T1) foi similar estatisticamente aos tratamentos T3, T4, T5 e T6 para a cerâmica Duceram LFC, em relação ao fator Ra; O tratamento T1 apresentou-se com diferença estatisticamente significante e mais rugoso que o tratamento T3, T4 e T6 para a cerâmica Duceram Plus, em relação ao fator Ra; As duas cerâmicas odontológicas avaliadas apresentaram... / This study assessed the efficacy of different current porcelain finishing and polishing procedures on two different dental ceramic (Duceram Plus and Duceram LFC) quantitatively with a profilometer. Forty disks (8 mm in diameter and 4 mm thick) were prepared for each dental ceramic according to the manufacturer's directions. Prior to glazing, all specimens' surfaces were abraded using a 240, 360 and 600-grit wet sandpaper. Then, all samples were glazed. The forty samples of each dental ceramic were divided into 8 groups of five specimens each, according to the surface treatment: T1- glaze; T2- abraded with fine and ultra fine diamond burs (KG Sorensen); T3- T2 following Sof-Lex (3M) polishing system; T4- T3 following diamond paste; T5- T2 following Super-Snap polishing kit (Shofu); T6- T5 following diamond paste; T7- Viking rubber wheels (KG Sorensen); T8- T7 following diamond paste. Five roughness measurements (Ra, æm) were performed on each disc using a profilometer with cut-off value of 0.25 mm and a tracing length of 1.25 mm and a speed of 0.1 mm per second. These values were tested using a two-way analysis of variance and Tukey test at 5% significance level. The result showed (to Ra factor) that T3, T4, T5 and T6 were the best surface treatment for both dental ceramic materials and were statistically equals; the glazed treatment (T1) was similar statistically to the polishing treatment T3, T4, T5 and T6 for Duceram LFC ceramic; the glazed treatment (T1) was different statistically and rougher than the polishing treatment T3, T4 e T6 for Duceram Plus ceramic; the two different dental ceramic had similar behavior when received the same surface treatment; and the diamond-abraded group (T2) had the rougher surface in both dental ceramic studied.

Orientador: Eduardo Carlos Bianchi / Banca: Luiz Eduardo de Angelo Sanchez / Banca: Leonardo Roberto da Silva / Resumo: O processo de retificação é um processo de acabamento, e, portanto, possui características como bom acabamento superficial e alta precisão dimensional e geométrica. As peças usinadas por este processo possuem um alto valor agregado, pois as mesmas já passaram por outros processos de usinagem e/ou tratamentos térmicos e revenimento. Um fator limitador do processo de retificação é a quantidade de calor gerada durante o mesmo, energia esta que é minimizada pela aplicação de fluidos de corte durante a retificação. Porém os fluidos utilizados, na maior parte dos casos são poluentes e contém substâncias prejudiciais à saúde, além de possuir um alto custo de compra, manutenção e descarte. Visando reduzir a quantidade de fluido utilizada durante o processo de retificação o presente trabalho foi proposto, com o objetivo de melhorar a técnica da mínima quantidade de lubrificação através da aplicação combinada com ar comprimido à baixa temperatura a fim de melhorar o efeito de refrigeração e assim minimizar a geração de calor na região de corte. Para avaliar a eficácia da técnica foram escolhidas as variáveis de acabamento como a rugosidade e a circularidade, e de eficiência do processo como o desgaste do rebolo e potência consumida durante a usinagem. Estes valores foram medidos para três métodos distintos de aplicação de fluidos de corte durante o processo de retificação, a fim de compará-los, o método proposto para o presente trabalho, CAMQL (técnica de mínima quantidade de fluido co... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Grinding is a finishing process, and therefore has characteristics such as good surface finish, high dimensional and geometric precision. Because it is this kind of manufacture process, the parts machined by this have a high added value, since they have already undergone other machining processes and/or heat treatments and tempering. A limiting factor of grinding process is the amount of heat generated during it; which energy is minimized by application of cutting fluids. But these fluids, in most cases are pollutants and could contain substances that are harmful to health, in addition to having a high cost of purchase, maintenance and disposal. In order to reduce the amount of fluid used during the grinding process, the present research has been proposed with the aim of improving the technique of minimum quantity of lubrication by the combined application with compressed air at low temperature in order to improve the cooling effect ant thus minimize the heat in cutting zone. To evaluate the effectiveness of this technique, the finishing variables such as roughness and roundness, and process efficiency, such as grinding wheel wear and power consumed during machining, were chosen. These values were measured for three different methods of cutting fluids application during the grinding process, in order to compare them, the proposed method, CAMQL (cold air minimum quantity of lubrication) as compared to conventional fluid application (flood) and the minimum quantity lubrication with air in room temperature. For all parameters, the proposed cutting fluid reduction reached, in general, positives results, proving its... (Complete abstract electronica acess below) / Mestre