CECÍLIO ALVARES DA CUNHA

CECÍLIO ALVARES DA CUNHA

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Effect of high energy milling parameters on nanostructured Cr3C2-Ni20Cr powder characteristics
2007 - PADIAL, A.; CUNHA, C.A.; AMBROZIO FILHO, F.; BRESSIANI, A.H.A.; MARTINELLI, J.R.; LIMA, N.B. de; RAMANATHAN, L.V.
Structure and properties of thermal sprayed nanostructured Crsub(3)Csub(2)-25(Ni20Cr) coatings
2009 - PADIAL, A.; CUNHA, C.A.; LIMA, N.B.; MARTINELLI, J.R.; CORREA, O.V.; RAMANATHAN, L.V.
Effect of high energy milling parameters on nanostructured Cr3C2-Ni20Cr powder characteristics
2008 - CUNHA, C.A.; PADIAL, A.G.F.; LIMA, N.B. de; MARTINELLI, J.R.; CORREA, O.V.; RAMANATHAN, L.V.
Cr3C2-NiCr coatings have been used for corrosion and wear resistant applications. In the last decade, thermal sprayed coatings using nanostructured feed stock of other materials has exhibited higher hardness, strength and corrosion resistance. Hence, it is anticipated that nanostructured Cr3C2-NiCr coatings will also exhibit these properties and therefore posses improved performance characteristics. Preparation of nanostructured feed stock powders is the first step in the synthesis of nanostructured coatings and mechanical milling is an effective process to obtain the powders. Preliminary studies in which commercial Cr 3C2-NiCr powders were milled in hexane and gaseous nitrogen revealed that particle and crystallite size were significantly smaller in powders milled in nitrogen. This paper presents the effect of hexane content and milling parameters on Cr3C2-Ni20Cr powder characteristics. Use of just sufficient hexane as the milling media reduced significantly the particle and crystallite sizes.
Microstructure and mechanical properties of thermal sprayed nanostructured Cr3C2-Ni20Cr coatings
2008 - CUNHA, CECILIO A. da; LIMA, NELSON B. de; MARTINELLI, JOSE R.; BRESSIANI, ANA H.A.; PADIAL, ARMANDO G.F.; RAMANATHAN, LALGUDI V.
Cr3C2-Ni20Cr coatings have been used for corrosion and wear resistant applications. However, one of the shortcomings of these coatings is its low hardness, and consequent low wear resistance, for long term high temperature applications. Nanostructured coatings of many materials have exhibited higher hardness and strength compared with conventional coatings of the same material. Consequently, nanostructured coatings of other materials, including Cr3C2-Ni20Cr have been attempted to enhance overall performance. In this study the effects of high energy milling parameters on Cr3C2- 25(Ni20Cr) powder characteristics as well as the microstructure and mechanical properties of nanostructured Cr3C2-25 (Ni20Cr) coatings formed by high velocity oxygen fuel (HVOF) spraying have been evaluated. The average particle size and crystallite size of milled Cr3C2-25 (Ni20Cr) powders decreased with increase in milling time and this decrease was more pronounced in nitrogen compared to that in hexane. This difference has been attributed to a cushioning effect in the latter medium. The coatings prepared with milled Cr3C2-25 (Ni20Cr) powders had a more uniform microstructure, were harder and had higher relative fracture toughness compared with coatings prepared with as-received powders.