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Metaliza??o mec?nica com Ti de placas de Al2O3 utilizando m?quina ferramenta computadorizada para brasagem metal/cer?micaVieira, Jo?o Dantas Paiva 22 August 2015 (has links)
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Previous issue date: 2015-08-22 / Neste trabalho empregou-se a t?cnica de metaliza??o mec?nica para produzir um revestimento de metal ativo, no caso o tit?nio (Ti), no substrato cer?mico de alumina (Al2O3), a fim de favorecer o molhamento com ligas de adi??o convencionais. Utilizou-se um processo autom?tico com o emprego de uma m?quina ferramenta de controle num?rico computadorizado (CNC) sem a interven??o do operador. Posteriormente, a cer?mica metalizada foi brasada, com tubo met?lico de inox 304, por t?cnica indireta em forno de alto v?cuo, utilizando liga de adi??o convencional Ag-28Cu. A interface resultante foi caracterizada por t?cnica de an?lise micro estrutural em microsc?pio eletr?nico de varredura (MEV) acoplado com sistema de microan?lise qu?mica por energia dispersiva (EDS) e o desempenho mec?nico, por ensaio de cisalhamento, realizado em uma m?quina universal de ensaios mec?nicos, que apresentou baixos valores da tens?o de cisalhamento. A metaliza??o com tit?nio mostrou resultado satisfat?rio com pode ser observado pelas an?lises microsc?picas, enquanto a brasagem apresentou diferen?as significativas, a menor, nos resultados de resist?ncia das amostras analisadas, quando comparadas a outros trabalhos, na mesma ?rea. / In this work employed the mechanical metallization technique to produce a thin film of
titanium in the ceramic substrate of alumina (Al2O3), in order to favor wetting with
conventional adding alloys. Was used an automated process with employment a
machine tool computer numerical control (CNC) without operator intervention.
Subsequently, the metallized ceramic was brazed with metallic stainless steel tube 304,
by indirect technique in high-vacuum oven, using conventional alloying addition Ag-
28Cu. The resulting interface was characterized by technique of micro structural
analysis using scanning electron microscopy (SEM) coupled with energy dispersive
spectroscopy (EDS) for chemical microanalysis and mechanical performance, shear test,
carried out on a universal testing machine. The titanium metallization film was observed
by electron microscopy showing an interface with good interaction between the
elements of the materials involved, and the thickness of the layer of titanium fairly
regular, consistent with results in the same work area. While brazing interface presented
some defects, mainly due to the furnace atmosphere and vacuum pressure, which has
not reached the specified value, identified in other studies, which influenced, to some
extent, the mechanical results.
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Estudo da influ?ncia da temperatura de brasagem nas uni?es zirc?nia/a?o inox 304 utilizando metaliza??o mec?nica / Study on the influence of brazing temperature in the joint zirconia/steel using mechanical metallizationCarneiro, Jaciane Mora?sa 30 July 2014 (has links)
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Previous issue date: 2014-07-30 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Metal-Ceramic (M/C) Zirconia-stainless steel interfaces have been processed through brazing techniques due to the excellent combination of properties such as high temperature stability, high corrosion resistance and good mechanical properties. However, some M/C interfaces show some defects, like porosity and cracks results in the degradation of the interfaces, leading even to its total rupture. Most of time, those defects are associated with an improper brazing parameters selection to the M/C system. In this work, ZrO2 Y-TZP and ZrO2 Mg - PSZ were joint with the stainless steel grade 304 by brazing using a eutectic silver-copper (Ag28Cu) interlayer alloy with different thermal cycles. Ceramic surfaces were previous mechanically metallized with titanium to improve adhesion of the system. The effect of temperature on the M/C interface was studied. SEM-EDS and 3 point flexural bend test were performed to evaluate morphology, chemical composition and mechanical resistance of the M/C interfaces. Lower thermal cycle temperatures produced better results of mechanical resistance, and more regular/ homogeneous reaction layers between braze alloy and metal-ceramic surfaces. Also was proved the AgCu braze alloy activation in situ by titanium / Interfaces metal/cer?mica zirc?nia/a?o inox processadas via brasagem v?m sendo utilizadas devido a sua combina??o de propriedades tais como: estabilidade em altas temperaturas, elevada resist?ncia ? corros?o e boas propriedades mec?nicas. Contudo, alguns pares apresentam problemas a n?vel da interface, como trincas, fissuras e porosidades, contribuindo assim para a deteriora??o do par metal/cer?mica, podendo at? conduzir ? ruptura total da interface. Esses defeitos na interface podem estar associados a uma sele??o menos criteriosa dos par?metros de brasagem para cada sistema. No presente trabalho utilizou-se a uni?o entre zirc?nia (Y-TZP e Mg PSZ) com a?o inox 304. Essas jun??es foram metalizadas mecanicamente com Ti e brasadas em diferentes ciclos t?rmicos utilizando liga de adi??o Ag-Cu. Microscopia Eletr?nica de Varredura (MEV) com microan?lise por espectroscopia de Energia Dispersiva (EDS) e teste de flex?o em 3 pontos foram empregadas para investigar as propriedades da uni?o zirc?nia/a?o. Os resultados revelaram que para menores temperaturas de brasagem houve uma melhor resist?ncia a flex?o e camadas de rea??o mais homog?neas entre a liga de adi??o e os pares metal/cer?mica. Ficou tamb?m comprovado a ativa??o in situ da liga de adi??o AgCu
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Metaliza??o mec?nica de ZrO2 com Ti para brasagem ZrO2/A?o com ligas de adi??o sem metal ativoSilva, Jo?o Moreno Vilas Boas de Souza 21 December 2011 (has links)
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Previous issue date: 2011-12-21 / Metal/ceramic interfaces using zirconia have dominated the industrial
applications in the last decade, due to the high mechanical strength and fracture
toughness of zirconia, especially at temperatures below 300 ?C. Also noteworthy is the
good ionic conductivity in high temperatures of this component. In this work joining
between ZrO2 Y-TZP and ZrO2 Mg-PSZ with austenitic stainless steel was studied.
These joints were brazed at high-vacuum after mechanical metallization with Ti using
filler alloys composed by Ag-Cu and Ag-Cu-Ni. The influence of the metallization, and
the affinity between the different groups (ceramic / filler alloys) was evaluated, in order
to achieve strong metal/ceramic joints. Evaluation of joints and interfaces, also the
characterization of base materials was implemented using various techniques, such as:
x-ray diffraction, leak test, three-point flexural test and scanning electron microscopy
with chemical analysis. The microstructural analysis revealed physical and chemical
bonds in the metal/ceramic interfaces, providing superior leak proof joints and stress
cracking, in order to a good joint in all brazed samples. Precipitation zones and reaction
layers with eutetic characteristics were observed between the steel and the filler metal / As interfaces metal/cer?micas utilizando zirc?nia t?m dominado as
aplica??es industriais na ?ltima d?cada, em virtude da alta resist?ncia
mec?nica e tenacidade ? fratura da zirc?nia, especialmente em temperaturas
abaixo de 300 ?C. Destaca-se tamb?m a boa condutividade i?nica em
temperaturas elevadas deste componente. No presente trabalho, estudou-se as uni?es
entre ZrO2 Y-TZP e ZrO2 Mg-PSZ com o a?o inox austen?tico 304. Estas jun??es foram
produzidas por brasagem a alto-v?cuo ap?s a metaliza??o mec?nica com Ti utilizandose
ligas de adi??o compostas por Ag-Cu e Ag-Cu-Ni. Avaliou-se a influ?ncia da
metaliza??o, bem como a afinidade entre os diversos grupos (cer?mica / liga de adi??o)
com o intuito de se conseguir a melhor uni?o metal/cer?mica. A avalia??o das uni?es e
interfaces, bem como a caracteriza??o dos materiais de base foi feita com recurso de
diversas t?cnicas, tais como: difra??o de raios-x, ensaios de estanqueidade, flex?o em 3-
pontos e microscopia eletr?nica de varredura com microan?lise por espectroscopia de
energia dispersiva de raios-x. A an?lise microestrutural revelou liga??es f?sicas e
qu?micas na interface metal/cer?mica, proporcionando boa estanqueidade e tens?o de
ruptura e, consequentemente, uma boa uni?o em todas as amostras brasadas. Foram
observadas zonas de precipita??o e camadas de rea??o com caracter?sticas eut?ticas
entre o a?o e o metal de adi??o
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