DESENVOLVIMENTO DE METAIS DUROS WC-Ni-Si PARA APLICAÇÕES DE ENGENHARIA
DEVELOPMENT OF CEMENTED CARBIDES WC-Ni-Si FOR ENGINEERING APPLICATIONS
Santos, Júlio Navarro; Klein, Aloisio Nelmo; Correa, Edmilson Otoni
http://dx.doi.org/10.4322/tmm.00603008
Tecnol. Metal. Mater. Min., vol.6, n3, p.162-166, 2010
Resumo
O objetivo deste trabalho é caracterizar mecânica e microestruturalmente compósitos WC-10(Ni-4,1%Si), conhecidos como metais duros, processados por metalurgia do pó. Observações microestruturais das amostras sinterizadas indicam a presença de uma porosidade muito baixa, bem como um livre caminho médio estreito e relativamente constante entre as partículas da fase dura. Além disso, a despeito da presença de silício e carbono na composição da liga, não se observa a presença de pequenas frações de carbonetos de silício não dissolvidos ou de grafita livre na microestrutura. Ensaios de dureza e de resistência à flexão indicam que o metal duro utilizando a liga de níquel endurecido com 4,1%Si, como ligante, apresenta dureza semelhante à dos metais duros WC-Co, porém, resistência à flexão e tenacidade à fratura superiores.
Palavras-chave
Metal duro, Caracterização microestrutural, Metalurgia do pó
Abstract
The aim of this work is to make a mechanical and micro structural characterization of a cemented carbide with silicon hardened nickel binder WC-10(Ni-4,1 % Si) processed by powder metallurgy techniques. Micro structural examinations of the specimens indicate the presence of a very low porosity as well as a narrow and relatively constant free mean path between the WC particles. Furthermore, despite the presence of silicon and carbon in the composition, it is not observed the presence of small fractions of non-dissolved SiC and/or free graphite in the microstructure. Vickers hardness and bending tests indicate that the cemented carbide with Ni-4,1% Si binder presented bulk hardness similar to the conventional WC-Co cemented carbides and superior bending resistance and fracture toughness.
Keywords
Cemented carbide, Microstructural characterization, Powder metallurgy
Referências
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5 OHRINER, E. K, et al. The chemistry and structure of wear-resistant iron-base hardfacing alloys. Metallurgical Transactions A, v. 22A, n. 5, p. 983-91, May 1991.
6 NASSAJ, E. T.; MIRHOSSEINI, S. H. An in situ WC-Ni composite fabricated by the SHS method. Journal of Materials Processing Technology, v. 42, n. 2, p. 422-426, Nov. 2003.
7 SCHATT, W. Powder metallurgy: sintered and composite materials (Pulvermetallurgie. Sinter-und Verbundwerstaffe). Leipzig: VEB Deutscher Verlag fur Grundstoffindustrie, 1979.
8 CHICOT, D., et al. New development for fracture toughness determination by Vickers Indentation. Materials Science and Technology, v. 20, n. 7, p. 877-83, July 2004.
9 SHETTY, D. K., et al. Indentation fracture of WC-Co cermets. Journal of Materials Science, v. 20, n. 5, p. 1873-82, May 1985.
10 RODRIGUES, M. F., et al. Sinterização da liga WC-10Co por altas pressões. Revista Matéria, v. 11, n.3, p.174-80, 2006.
11 GRATHWOHL, G.; WARREN, R. Effect of cobalt content on microstructure of liquid-phase sintered TaC-Co alloys. Materials Science and Engineering A, v. 14, n. 1, p. 55-65, Apr. 1974.
2 KIM, H. C., et al. Fabrication of ultrafine binderless WC and WC-Ni hard materials by a pulsed current activated sintering method. Journal of Ceramic Processing Research, v. 7 n. 3, p. 224-9, 2006.
3 FERNANDES, C. M., et al. Mechanical characterization of composites prepared fom WC powdes coated with Ni rich binders. International Journal of Refractory Metals and Hard Metals, v. 26, n. 5, p. 491-8, Sept. 2008.
4 JIANG, G.; ZHUANG, H.; LI, W. Parameters investigation during simultaneous synthesis and densification WC-Ni composites by field-activated combustion. Materials Science and Engineering A, v. 360, n. 1-2, p. 377-384, Nov. 2003.
5 OHRINER, E. K, et al. The chemistry and structure of wear-resistant iron-base hardfacing alloys. Metallurgical Transactions A, v. 22A, n. 5, p. 983-91, May 1991.
6 NASSAJ, E. T.; MIRHOSSEINI, S. H. An in situ WC-Ni composite fabricated by the SHS method. Journal of Materials Processing Technology, v. 42, n. 2, p. 422-426, Nov. 2003.
7 SCHATT, W. Powder metallurgy: sintered and composite materials (Pulvermetallurgie. Sinter-und Verbundwerstaffe). Leipzig: VEB Deutscher Verlag fur Grundstoffindustrie, 1979.
8 CHICOT, D., et al. New development for fracture toughness determination by Vickers Indentation. Materials Science and Technology, v. 20, n. 7, p. 877-83, July 2004.
9 SHETTY, D. K., et al. Indentation fracture of WC-Co cermets. Journal of Materials Science, v. 20, n. 5, p. 1873-82, May 1985.
10 RODRIGUES, M. F., et al. Sinterização da liga WC-10Co por altas pressões. Revista Matéria, v. 11, n.3, p.174-80, 2006.
11 GRATHWOHL, G.; WARREN, R. Effect of cobalt content on microstructure of liquid-phase sintered TaC-Co alloys. Materials Science and Engineering A, v. 14, n. 1, p. 55-65, Apr. 1974.
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