Wilson Corrêa Rodrigues

Comparative studies of WC-Co and WC-Co-Ni composites obtained by conventional powder metallurgy

The present work reports a comparative study of cemented carbides of compositions WC-6Co, WC-10Co, WC-20Co, WC-6Co-6Ni and WC-12Ni-6Co. The purpose was to study the powder metallurgical production process of these compositions starting from a commercial WC-6Co powder, obtaining the desired compositions by mass balance with pure Co and pure Ni powders. During the process steps mixing, milling, compacting and sintering the powders were described by its apparent density, green density, shrinkage and sintered density. Lower densities were observed in composites with higher binder content. The process was monitored by scanning electron microscopy and EDS analysis to evaluate the homogeneity of the powders, to detect contaminations by the process and to characterize the microstructure of the sintered materials. A finer microstructure was found when the binder contained Ni. Potentiodynamic polarization tests in sulfuric acid revealed pseudo-passive behavior for all the tested hard metals.

Design and Development of Compaction Tools for Powder Metallurgy

The aim of this work is to analyse options of different powder metallurgy tools design with upper punch adapted with springs and its benefits with regards green density of the parts compacted in hydraulic press. Crack of the parts also were observed.

Obtaining sintered parts of titanium applied in medical field

The aim of this work is the study of sintered titanium parts for medical applications components, via process of Powder Metallurgy (M/P). This study will be a basis for the manufacture of an orthodontic interpenetrating screw. A study of constituent powders was accomplished and samples were prepared. In sequence, its physical properties were analyzed. For all alloy composition studied, the parameters of production process were respected as: compactation pressure, sintering atmosphere, and sintering time. The porosity determined by Archimedes principle was approximately 11.5%. This result is comparable to that found in the literature. The average density obtained by M/P was 4.03 g/cm3 for sintered titanium, with a density close to theoretical density of titanium, 4.5 g/cm3. Key words: powder metallurgy, sintering, orthodontic screw.

Ring test for evaluation of behavior of the friction coefficient of aluminum alloy

O objetivo deste trabalho e realizar um estudo comparativo sobre a influencia de lubrificantes no coeficiente de atrito da liga de aluminio AA6351. O atrito tem um efeito significativo na deformacao do material, alterando a forca de compressao e o desgaste da matriz e da peca. A escolha de um lubrificante com eficiencia na reducao do atrito da interface peca/matriz aumenta a vida util da ferramenta e, consequentemente, melhora a margem de lucro quando em producao industrial. Para o forjamento de ligas de aluminio, recomendam-se lubrificantes a base de grafite e agua ou grafite e oleo. Neste estudo, tres lubrificantes comerciais foram testados: grafitado ( Aerodag G ), sintetico ( Synd Forg 100-A ) e um a base de oleo ( Dechelub 5562 ). A metodologia adotada: obtencao de corpos de prova, ensaio do anel em prensa hidraulica variando-se os lubrificantes, simulacao em programa computacional para aquisicao das curvas de calibracao e comparacao dos resultados. Comparando os dados experimentais com as curvas obtidas por simulacao foi verificado que, entre os tres lubrificantes testados, o sintetico obteve o melhor desempenho, seguido do lubrificante a base de oleo. O lubrificante a base de grafite obteve um desempenho inferior para essa aplicacao. Palavras-chave: aluminio, atrito, simulacao computacional e lubrificacao.

Effect of addiction of Nb, Mo, Cr and Ti on the microstructure of WC-6Co

Hard metals are a group of materials known as sintered composites involving hard phases (carbides) with a metallic phase, being widely used in applications where you want high hardness and wear resistance combined with high toughness. This article presents the results of adding 1% by weight of the elements Nb, Ti, Cr and Mo on the microstructure of the hard metal from a commercial composite of WC-6Co. In this composite was added 1.5% (by weight) of zinc stearate as lubricant and sintered at a temperature of 1450oC in an atmosphere of argon. Aiming to analyze the product efficiency was held on micro structural characterization through the testing of green density, shrinkage, sintered density, microstructure and microhardness. Key words: hard metal, carbide, balancing mass, powder metallurgy, sintering.

A study of Al-Mo powder processing as a possible way to corrosion resistent aluminum-alloys

Elementary Al and Mo powder mixtures have been processed by high energy ball milling up to milling times of 100 hours. The shift of the pitting potential and the X ray analysis of green milled samples showed that part of the Mo has formed a supersaturated solid solution of Mo in Al. Elementary Mo powder, however, was still present after 100 hours of milling. Sintering led to the formation of the intermetallic Al12Mo phase.

Influence of the bismuth on mechanical properties of high speed steel AISI M2 sintered

A adic ao de bismuto em uma liga de aco AISI M2 produzida por metalurgia do po foi avaliada, buscando melhorar a usinabilidade e as propriedades mecânicas deste material. Para este estudo, foram analisadas as amostras de aco rapido AISI M2 com os seguintes teores de bismuto: 0.1%, 0.3%, 0.5% e 1%. O processo de conformacao do po realizou-se atraves da compactacao uniaxial a 600 MPa e sinterizacao sob atmosfera protetora de 95%N2 + 5%H2. A temperatura de sinterizacao utilizada foi de 1.130°C. As amostras apresentar am um aumento proporcional da porosidade com o acrescimo percentual de bismuto. No ensaio de desgaste e de compressao a amostra de 0,3% de bismuto apresentou menor resistencia mecânica. No ensaio de usinabilidade as amostras de M2 e a M2 com 1% de bismuto The addition of bismuth in an alloy steel AISI M2 produced by powder metallurgy, has been evaluated aiming to improve the machinability and m echanical properties of this material. For this study, were analyzed samples of AISI M2 steel quick with the following levels of bismuth: 0.1%, 0.3%, 0.5% and 1%. The process of shaping the powder was carried out by uniaxial compaction at 600 MPa and sinte ring in protective atmosphere of 95% N2 + 5% H2. The sintering temperature used was 1130 ° C. The samples showed a proportional increase of porosity with increasing percentage of bismuth. In the test of wear and compression of the sample of 0.3% of bismuth showed lower mechanical strength. Machinability testing of the samples of M2 and M2with 1% of bismuth sintered obtained chips shear (in the form of needle) and chip block (as arcs), respectively.