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The study of ternary carbides formation during SPS consolidation process in the WC-Co-steel system

MACHADO, Izabel Fernanda; GIRARDINI, Luca; LONARDELLI, Ivan; MOLINARI, Alberto
Fonte: ELSEVIER SCI LTD Publicador: ELSEVIER SCI LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.81%
Tungsten carbide has a wide range of applications, mainly cemented carbides made of WC and Co, as wear resistant materials. However, the high cost of WC-Co powders encourages the use of a substrate to manufacture a functionally graded material (FGM) tool made of WC-Co and a tool steel. These materials join the high wear resistance of the cemented carbide and the toughness of the steel. This work deals with the study interaction of the WC-Co and H13 steel to design a functionally graded material by means of spark plasma sintering (SPS). The SPS, a novel sintering technique reaching the consolidation of the powders at relatively low temperatures and short dwell times, is a promising technique in processing materials. In this study, WC, H13 steel, WC-Co, WC-H13 steel and WC-Co-H13 steel bulk samples were investigated using scanning electron microscopy and X-ray diffraction techniques to evaluate the phase transformations involved during SPS consolidation process. The W(2)C and W(3)Fe(3)C precipitation were identified after the SPS consolidation of the WC and WC-H13 steel samples, respectively. The precipitation Of W(4)Co(2)C was also identified in the WC-Co and WC-Co-H13 steel samples. The WC-H 13 steel and WC-Co-H13 steel were also evaluated after heat treatments at 1100 degrees C for 9 h...

Estudo das propriedades mecânicas dos compósitos WC-6Co, WC-10Co, WC-20Co, WC-6Co-6Ni, WC-6Co-12Ni obtidos por metalurgia do pó convencional para aplicação em anéis de selos mecânicos

Martins, Vinicius
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
46.53%
O presente trabalho tem como objetivo o estudo das propriedades mecânicas do metal duro nas composições WC-6Co, WC-10Co, WC-20Co, WC-6Co-6Ni, WC-6Co-12Ni, obtidos por metalurgia do pó convencional para aplicação em anéis de selos mecânicos. Estes compósitos foram obtidos a partir de uma composição comercial de WC-6Co, e adicionado cobalto e níquel para realização do balanço de massa. Determinou-se um procedimento de obtenção das composições, através de cálculos de balanceamento adicionando-se a quantidade de cobalto e níquel necessária para transformar um compósito comercial 94WC-6Co nos metais duros mencionados. Após este procedimento adicionou-se 1,5% de lubrificante, em um misturador em “Y”. Analisou-se no Microscópio eletrônico de varredura a homogeneidade das composições. Determinou-se a densidade aparente, a curva de compressibilidade e compactaram-se as amostras de metal duro obtendo-se as densidades a verde. Realizou-se a pré-sinterização e determinaram-se as densidades das peças présinterizadas, executou-se ensaio de compressão e obtiveram-se parâmetros de usinagem na operação de faceamento e furação dos corpos de prova pré-sinterizados. A sinterização foi realizada em diversas vezes...

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

Martins, Vinicius; Rodrigues, Wilson Correa; Ferrandini, Peterson Luiz; Villarinho, Denis Jardim; Knörnschild, Gerhard Hans; Schaeffer, Lirio
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
Relevância na Pesquisa
56.66%
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.

Influence of HVOF parameters on the corrosion and wear resistance of WC-Co coatings sprayed on AA7050 T7

Magnani, M.; Suegama, P. H.; Espallargas, N.; Dosta, S.; Fugivara, C. S.; Guilemany, J. M.; Benedetti, A. V.
Fonte: Elsevier B.V. Sa Publicador: Elsevier B.V. Sa
Tipo: Artigo de Revista Científica Formato: 4746-4757
ENG
Relevância na Pesquisa
66.47%
Thermal spray WC-based coatings are widely used in the aircraft industry mainly for their resistance to wear, reworking and rebuilding operations and repair of worn components on landing gear, hydraulic cylinders, actuators, propeller hub assemblies, gas turbine engines, and so on. The aircraft industry is also trying to use thermal spray technology to replace electroplating coatings such as hard chromium. In the present work, WC-Co coatings were built up on an AA 7050 aluminum alloy using high velocity oxygen fuel (HVOF) technology and a liquid nitrogen cooling prototype system. The influence of the spray parameters (standard conditions, W19S, increasing the oxygen flux, W19H, and also increasing the carrier gas flux, W19F) on corrosion, friction, and abrasive wear resistance were also studied. The coatings were characterized using optical (OM) and scanning electron (SEM) microscopy, and X-ray diffraction (XRD). The friction and abrasive wear resistance of the coatings were studied using Rubber Wheel and Ball on Disk tests. The electrochemical studies were conducted using open-circuit potential (E(oc)) measurements and electrochemical impedance spectroscopy (EIS). Differences among coated samples were mainly related to the variation of the thermal spray parameters used during the spray process. No significant differences were observed in the wear resistance for the coatings studied...

SAE 1045 steel/WC-Co/Ni-Cu-Ni/SAE 1045 steel joints prepared by dynamic diffusion bonding: Microelectrochemical studies in 0.6 M NaCl solution

Andreatta, Francesco; Matesanz, Laura; Akita, Adriano H.; Paussa, Luca; Fedrizzi, Lorenzo; Fugivara, Cecilio S.; Gomez de Salazar, Jose M.; Benedetti, Assis V.
Fonte: Pergamon-Elsevier B.V. Ltd Publicador: Pergamon-Elsevier B.V. Ltd
Tipo: Artigo de Revista Científica Formato: 551-559
ENG
Relevância na Pesquisa
46.43%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Processo FAPESP: 07/53633-0; Corrosion of SAE 1045 steel/WC-Co/Ni-Cu-Ni/SAE 1045 steel interfaces was investigated in 0.6 M NaCl solution using an electrochemical microcell, which enables local electrochemical characterization at the micrometer scale. Two pieces of steel, one with a WC-Co coating covered with Ni (12 mu m) and Cu (5 mu m) layers, and the other with a Ni (15 mu m) layer,were welded by dynamic diffusion bonding. AWC-Co coating was applied to the steel by the high velocity oxygen-fuel process, and Ni-Cu and Ni layers by electroplating. Polarization curves were recorded using an electrochemical microcell. Different regions of welded samples were investigated, including steel, cermet coating, and steel/cermet and steel/Ni-Cu-Ni/cermet interfaces. Optical and electronic microscopes were employed to study the corroded regions. Potentiodynamic polarization curves obtained using the microcell revealed that the base metal was more susceptible to corrosion than the cermet. In addition, cermet steel/cermet and steel/Ni-Cu-Ni/cermet joints exhibited different breakdown potentials. Steel was strongly corroded in the regions adjacent to the interfaces...

Deposição de revestimentos compositos metal-ceramico WC-Co por fusão a laser : avaliação da resistencia ao desgaste e a corrosão

Maria Aparecida Pinto
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 16/02/2004 PT
Relevância na Pesquisa
46.7%
No presente trabalho o processo de deposição por fusão a laser foi usado para produzir revestimentos com o compósito WC-Co, a partir da mistura dos pós de WC e Co, com frações variadas de WC. O substrato usado foi o aço AISI 1045. Os revestimentos foram produzidos após vários testes para a determinação experimental dos parâmetros de processo. A caracterização dos revestimentos foi feita por microscopia ótica, microscopia eletrônica de varredura, difração de raios-X e microdureza Vickers. Para analisar o comportamento dos revestimentos foram executados ensaios de desgaste abrasivo à escala micro do tipo esfera-sobre-placa e ensaios eletroquímicos para avaliar o comportamento em corrosão. Os revestimentos apresentaram-se sem trincas ou porosidade e com uma microestrutura heterogênea. A estrutura básica é formada por carbonetos WC e Co3 W3C sobre uma matriz, constituída de uma solução sólida de (W, Cr) em cobalto. O carboneto Co3W3C é resultante da dissolução do carboneto WC. O revestimento que apresentou melhor resistência ao desgaste abrasivo foi aquele produzido com a mistura de 20% WC + 80%Co (em peso). No comportamento em corrosão o melhor resultado apresentado foi o do revestimento formado pela mistura 40% WC + 60%Co (em peso); In the present work the laser c1adding process was used to produce WC-Co composite coatings with varied fractions of WC. The AISI 1045 steel was used as substrate. The coatings were produced afier severa! tests...

Desempenho de filmes de diamante no desgaste de matrizes de corte em WC-Co

Oliveira, Francisco José Dias
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Dissertação de Mestrado
POR
Relevância na Pesquisa
46.4%
O presente trabalho consistiu fundamentalmente na optimização de ferramentas de corte e de desgaste para telas abrasivas. Para o efeito desenvolveu-se uma ferramenta de corte multi-furo que permitisse cortar e furar simultaneamente dois discos de tela abrasiva. De modo a aumentar o tempo de vida das ferramentas de corte analisouse em detalhe o desempenho de filmes de diamante em matrizes de corte em substrato de WC-Co. Face aos resultados obtidos relativos à adesão do filme de diamante ao substrato e à resistência ao desgaste foi possível produzir um filme em condições reais que permitiu a diminuição significativa do desgaste das matrizes triplicando o seu tempo de vida. ABSTRACT: The present work was fundamentally in the optimization tools for cutting and wear for abrasive sand paper. To this end it has developed a cutting tool that would allow multi-hole cut and drill two sand paper discs simultaneously. In order to increase the life of tools is examined in detail the performance of films, dies in diamond cutting in substrate of WC-Co. Given the results concerning the accession of the film of the diamond substrate and the resistance to wear was possible to produce a film in real conditions that led to the significant decrease the erosion of matrices tripling its lifetime.; Mestrado em Engenharia Mecânica

Diamante nanocristalino CVD sobre graus WC-Co submicrométricos

Pires, Filipe de Sousa
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Dissertação de Mestrado
POR
Relevância na Pesquisa
46.64%
O diamante possui propriedades mecânicas, térmicas e eléctricas excepcionais que o tornam um material de eleição para várias aplicações. A deposição de filmes finos de diamante CVD encontrou uma das suas mais promissoras aplicações na área das ferramentas de corte. Devido à elevada dureza, estes revestimentos são muito interessantes para aplicações tribológicas. O objectivo deste trabalho consistiu no estudo da adesão de revestimentos de diamante obtidos pela técnica de HFCVD em substratos de metal submicrométricos. Estudou-se o efeito de diferentes teores de cobalto e tamanhos de grão de WC. Foram realizados ataques químicos de modo a preparar a superfície de WC-Co para a deposição de diamante, minimizando assim o efeito prejudicial do cobalto e melhorando a ancoragem mecânica do diamante. Produziram-se assim amostras com vários tipos de revestimento, nomeadamente, diamante microcristalino (MCD) e diamante nanocristalino facetado (f-NCD). Através das técnicas de microscopia electrónica de varrimento, espectroscopia de Raman, perfilometria e microscopia de força atómica, foi possível caracterizar os diferentes substratos e filmes de diamante. Foi estudado o comportamento tribológico dos diversos filmes...

The role of the binder phase in the WC-Co sintering

Silva,A.G.P. da; Schubert,W.D.; Lux,B.
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2001 EN
Relevância na Pesquisa
46.66%
The sintering of hardmetal in the solid state is studied. The influence of the WC particle size on the sintering kinetics, the role of the binder phase in the densification process and how sintering depends on the heating conditions are investigated. It is observed that alloys with different WC particle size show quite different structural evolution during sintering, although the densification mechanisms are the same. This is explained by the formation of agglomerates of WC and Co. Hardmetal alloys can sinter very rapidly when high heating rates are used, since rapid heating accelerates the binder spreading and the formation of WC-Co agglomerates. The binder phase (Co) spreads on the WC particles initially as a thin layer. Subsequently, more Co spreads on this layer and WC-Co agglomerates are formed.

Properties of amorphous SiC coatings deposited on WC-Co substrates

Costa,A.K.; Camargo Jr,S.S.
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2003 EN
Relevância na Pesquisa
46.22%
In this work, silicon carbide films were deposited onto tungsten carbide from a sintered SiC target on a r.f. magnetron sputtering system. Based on previous results about the influence of r.f. power and argon pressure upon the properties of films deposited on silicon substrates, suitable conditions were chosen to produce high quality films on WC-Co pieces. Deposition parameters were chosen in order to obtain high deposition rates (about 30 nm/min at 400 W rf power) and acceptable residual stresses (1.5 GPa). Argon pressure affects the energy of particles so that films with higher hardness (30 GPa) were obtained at low pressures (0.05 Pa). Wear rates of the coated pieces against a chromium steel ball in a diamond suspension medium were found to be about half of the uncoated ones. Hardness and wear resistance measurements were done also in thermally annealed (200-800 °C) samples revealing the effectiveness of SiC coatings to protect tool material against severe mechanical degradation resulting of high temperature (above 500 °C) oxidation.

Microstructure and mechanical properties of WC-Co reinforced with NbC

Acchar,Wilson; Zollfrank,Cordt; Greil,Peter
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2004 EN
Relevância na Pesquisa
46.66%
Cemented carbides such as tungsten carbide-cobalt WC-Co composites have been widely used as cutting tool materials. Several reports have shown the influence of different factors such as grain size, type and amount of binder phase and the addition of hard particles on the properties of WC-Co. The purpose of this work was to investigate the effect of niobium carbide on the microstructure and mechanical properties of WC-Co. Specimens of WC-Co reinforced with NbC were mixed and subsequently hot-pressed in a inert atmosphere. The WC-Co-NbC composite material exhibited high hardness values (18.9 GPa), flexural strength (2100 MPa) and fracture toughness (11.2 MPa.m½ ). TEM analysis has shown a bimodal grain size distribution of WC.

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

Martins,Vinícius; Rodrigues,Wilson Corrêa; Ferrandini,Peterson Luiz; Villarinho,Denis Jardim; Knörnschild,Gerhard Hans; Schaeffer,Lírio
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
Relevância na Pesquisa
56.69%
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.

Bonding CVD diamond to WC-Co by high pressure : high temperature processing

Balzaretti, Naira Maria; Pereira, Altair Soria; Camerini, Rafael Vieira; Santos, Sérgio Ivan dos; Jornada, João Alziro Herz da
Fonte: Inmetro - Instituto Nacional de Metrologia, Qualidade e Tecnologia Publicador: Inmetro - Instituto Nacional de Metrologia, Qualidade e Tecnologia
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.46%
6 p. : il.; ABSTRACT: In this work we investigate the effect of processing at high pressure-high temperature (HPHT) on the adhesion of CVD diamond coatings on WC-Co substrates. The samples consisted of WC-Co substrates coated with thin diamond films (10 – 40 μm thick) grown by microwave plasma (MWCVD) CVD. The substrates were previously etched in order to remove the Co from the surface region. The adhesion of the film and its wear resistance improved after the HPHT treatment. SEM images of the cross section of the coated substrate revealed that Co infiltrated back to the region where it was previously removed. The results indicate that it is possible to take advantage of the HPHT plants already available around the world to produce, besides PCD’s and diamond powder, high-performance CVD diamond cutting tools with the advantage of requiring less demanding processing conditions.

Simulação computacional de medidas estereológicas em estruturas de metal duro (WC-Co)

Esteves, Ezequias Matos
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Ciência e Engenharia de Materiais; Processamento de Materiais a partir do Pó; Polímeros e Compósitos; Processamento de Materiais a part Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Ciência e Engenharia de Materiais; Processamento de Materiais a partir do Pó; Polímeros e Compósitos; Processamento de Materiais a part
Tipo: Tese de Doutorado Formato: application/pdf
POR
Relevância na Pesquisa
46.52%
This work focuses on the creation and applications of a dynamic simulation software in order to study the hard metal structure (WC-Co). The technological ground used to increase the GPU hardware capacity was Geforce 9600 GT along with the PhysX chip created to make games more realistic. The software simulates the three-dimensional carbide structure to the shape of a cubic box where tungsten carbide (WC) are modeled as triangular prisms and truncated triangular prisms. The program was proven effective regarding checking testes, ranging from calculations of parameter measures such as the capacity to increase the number of particles simulated dynamically. It was possible to make an investigation of both the mean parameters and distributions stereological parameters used to characterize the carbide structure through cutting plans. Grounded on the cutting plans concerning the analyzed structures, we have investigated the linear intercepts, the intercepts to the area, and the perimeter section of the intercepted grains as well as the binder phase to the structure by calculating the mean value and distribution of the free path. As literature shows almost consensually that the distribution of the linear intercepts is lognormal, this suggests that the grain distribution is also lognormal. Thus...

Análise do efeito do tempo da moagem de alta energia no tamanho de cristalito e microdeformação da rede cristalina do WC-Co

Pinto, Gislâine Bezerra
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Engenharia Mecânica; Tecnologia de Materiais; Projetos Mecânicos; Termociências Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Engenharia Mecânica; Tecnologia de Materiais; Projetos Mecânicos; Termociências
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
66.85%
Hard metals are the composite developed in 1923 by Karl Schröter, with wide application because high hardness, wear resistance and toughness. It is compound by a brittle phase WC and a ductile phase Co. Mechanical properties of hardmetals are strongly dependent on the microstructure of the WC Co, and additionally affected by the microstructure of WC powders before sintering. An important feature is that the toughness and the hardness increase simultaneously with the refining of WC. Therefore, development of nanostructured WC Co hardmetal has been extensively studied. There are many methods to manufacture WC-Co hard metals, including spraying conversion process, co-precipitation, displacement reaction process, mechanochemical synthesis and high energy ball milling. High energy ball milling is a simple and efficient way of manufacturing the fine powder with nanostructure. In this process, the continuous impacts on the powders promote pronounced changes and the brittle phase is refined until nanometric scale, bring into ductile matrix, and this ductile phase is deformed, re-welded and hardened. The goal of this work was investigate the effects of highenergy milling time in the micro structural changes in the WC-Co particulate composite...

Fatigue behavior of a structural steel coated with a WC–10Co–4Cr/Colmonoy 88 deposit by HVOF thermal spraying

LA BARBERA-SOSA, J.-G.; SANTANA, Y.Y.; VILLALOBOS-GUTIERREZB, C.; CHICOT, D.; LESAGE, J.; DECOOPMAN, X.; IOST, Alain; STAIA, M.H.; PUCHI-CABRERA, E.S.
Fonte: Elsevier Publicador: Elsevier
Relevância na Pesquisa
46.23%
The fatigue behavior of a SAE 4340 steel, coated with a 50% WC–10Co–4Cr/50% Colmonoy 88 deposit, by high velocity oxygen fuel (HVOF) thermal spray, has been investigated. The change in the maximum alternating stress with the number of cycles to fracture has been described by means of the relationship advanced by Stromeyer. A fractographic analysis has been carried out on some representative fracture surfaces, by means of scanning electron microscopy (SEM) techniques. The mechanical properties of the coating were characterized by means of nanoindentation tests. The results indicate that the coating is highly heterogeneous. Its deposition gives rise to a decrease in the fatigue strength of the substrate of ∼ 30%, in comparison with the uncoated substrate. The decrease in fatigue strength is due to the presence of stress concentrators at the substrate–coating interface, as well as the intrinsic characteristics of the coating.

Effect of nanostructuring and Al alloying on friction and wear behaviour of thermal sprayed WC-Co coatings

Basak, Animesh Kumar; Celis, J.-P.; Vardavoulias, M; Matteazzi, P
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.4%
Nanostructured WC-Co and WC-Co-Al coatings, with about 300-μm as-deposited coating thickness, were deposited by high velocity oxy-fuel (HVOF) spraying. Agglomerated nanostructured cermet powders produced by the Mechanomade ® process was used for HVOF sp

Desarrollo de moldes de prensado con recubrimientos antidesgaste; Pressing dyes development with wear resistant coatings

Poyatos, A.; Tur, F.; Pérez, J. A.; Rodríguez Barbero, Miguel Ángel
Fonte: Sociedad Española de Cerámica y Vidrio Publicador: Sociedad Española de Cerámica y Vidrio
Tipo: Artículo Formato: 319477 bytes; application/pdf
SPA
Relevância na Pesquisa
46.51%
[ES] El objetivo del presente trabajo ha sido el desarrollo de una nueva concepción de moldes de prensado para la industria del pavimento y revestimiento cerámicos. El empleo de recubrimientos con materiales compuestos metal-cerámica ha permitido, además de multiplicar la vida útil de los moldes por un factor entre 2 y 3 (1.000.000 – 1.500.000 ciclos de prensado), emplear aceros más económicos en la producción del molde, su reutilización, eliminar etapas de alto consumo energético, como el templado, que además provocan gran número de rechazos en el proceso, todo ello sin un incremento desmesurado en los costes directos respecto a los del procedimiento tradicional. Como método para la obtención del recubrimiento se ha empleado la proyección a alta velocidad, conocida por sus siglas en ingles HVOF (Hiper Velocity Oxi-Fuel spraying). Esta técnica combina las temperaturas relativamente elevadas de la llama de Hidrógeno o Acetileno con la energía cinética muy elevada que proporcionan las velocidades supersónicas de proyección (700 – 1100 m/s). Como material de recubrimiento se ha empleado un compuesto WC-Co en relación 80-20 (% en peso). Estas características han permitido obtener recubrimientos con porosidad casi nula...

Microestructura y propiedades mecánicas de carburos cementados de wc-nbc-co

Centeno,Oscarly; Sáez,Adolfredo; Piñero,María A; Castro,Gustavo; Barrios,Estebán; Arenas,Freddy J
Fonte: Universidad Simón Bolívar; ; Publicador: Universidad Simón Bolívar; ;
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2008 ES
Relevância na Pesquisa
46.41%
Se evaluó la densificación, fases constituyentes y cambios microestructurales, dureza y tenacidad de una serie de sólidos de WC-NbC-10%Co, con porcentajes nominales en peso de NbC variable entre 0 y 20%. Los sólidos estudiados fueron manufacturados mediante técnicas convencionales de pulvimetalurgia. La caracterización microestructural de los compactos sinterizados fue realizada utilizando Difracción de Rayos X (DRX), Microscopia Electrónica de Barrido (MEB) y Análisis Químico de Rayos X por Dispersión de Energía (EDX). La tenacidad fue determinada por la medida de longitud de grieta generada en la indentación tipo Vickers. La densificación y dureza del material aumenta con la adición de NbC a la composición base de WC-10%Co. La microestructura reveló granos de (W,Nb,)C morfología irregular y tamaño heterogéneo.

Desgaste de recubrimientos WC-Co-NiCrBSi tratados térmicamente

Rodríguez,María de los A; Gil,Linda; Pérez,Rafael; Ferrara,Salvador
Fonte: Universidad Simón Bolívar; ; Publicador: Universidad Simón Bolívar; ;
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2009 ES
Relevância na Pesquisa
66.51%
Los recubrimientos WC-Co depositados por rociado térmico son utilizados comúnmente en aplicaciones industriales en las cuales alta resistencia al desgaste es requerida. Sin embargo, los recubrimientos obtenidos por estas técnicas son susceptibles de presentar ciertos problemas como lo son: partículas no fundidas o semi-fundidas, pobre adhesión al substrato, baja cohesión entre partículas y otros defectos que pueden afectar el comportamiento del recubrimiento. Este trabajo tiene como propósito investigar el efecto del tratamiento posterior mediante el uso de una llama oxiacetilénica, sobre la resistencia al desgaste de un recubrimiento WC-Co-NiCrBSi depositado, mediante la técnica de alta velocidad oxígeno-combustible (HVOF), sobre un substrato de acero AISI 1020. La resistencia al desgaste de los recubrimientos con y sin tratamiento térmico posterior fue evaluada a través de ensayos de erosión, abrasión y deslizamiento con arreglo bola sobre disco. Se determinó que la resistencia a la abrasión del recubrimiento tratado térmicamente aumentó en un 67% comparado con la muestra sin tratamiento, lo cual puede ser atribuido a una menor porosidad, endurecimiento de la matriz y mejor cohesión entre las partículas, otorgadas por el tratamiento térmico. Sin embargo...