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RESUMOCarbonado é a denominação de um diamante policristalino opaco e de cor escura, naturalmente encontrado no Brasil e na República Central Africana. Artificialmente é possível produzir-se um diamante sintético policristalino do tipo carbonado. Devido a sua microestrutura constituída de muitos grãos, este diamante é mais duro e mais tenaz que os comuns. Assim, pode ser usado com vantagens em brocas para perfuração de petróleo e outras ferramentas resistentes à abrasão. O objetivo deste trabalho foi, pela primeira vez, produzir o carbonado no Brasil e apresentar suas características microestruturais. Este carbonado foi sintetizado a altas pressões e temperaturas utilizando grafite brasileiro no setor de Materiais Superduros da UENF. As características avaliadas o colocam como um material compatível para utilização em ferramentas de corte e perfuração.Palavras chaves: Diamante policristalino sintético, carbonado, microestrutura, resistência à abrasão, materiais superduros. Microstructural characteristics of brazilian graphite produced carbonado diamond ABSTRACTCarbonado is the name given to a polycrystalline, opaque and dark color diamond, which is naturally found in Brazil and in the Central Republic of Africa. Artificially, it is possible to produce a carbonado type synthetic polycrystalline diamond. Owing to its microstructure, which is constituted by many grains, this diamond is harder and tougher than the common ones. Therefore, it can be used with advantage in petroleum perforation drill and other wear resistant tools. The objective of this work was, for the first time, to produce a synthetic carbonado in Brazil and to present its microstructural characteristics. This carbonado was synthesized at high pressure and high temperature, using Brazilian graphite, at the sector of Superhard Materials of the State University of the Northern Rio de Janeiro, UENF. The evaluated characteristics indicated that this carbonado is a proper material for cutting and drilling tools.

One way to develop a new composite material or to improve its performance is to reinforce the matrix with a stronger dispersive phase. In principal, nanodiamonds can be used as reinforcement of composites owing to high surface energy, which allows an effective structure interaction with most utilized matrices. In this work, polycrystalline metallic–based composites and polymeric-based composites were investigated for the effect caused by addition of nanodiamonds. These composites were obtained at high compression pressures and combine with temperatures for certain short processing times. It was found that even small additions of nanodiamonds increase the wear resistance of the investigated composites.