CuZn-SiC metal-matrix composite coatings obtained by electrodeposition from alkaline non-cyanide solutions. Mechanical, physical and chemical characterizations.
Ana Paula Rocha de Almeida1; Felipe Delapria Dias dos Santos1; Rafael Leandro Felix1; Zulema Angela Mahmud2; Ivani Aparecida Carlos3; Paulo Cezar Tulio1
1 Universidade Tecnológica Federal do Paraná - câmpus Cornélio Procópio.; 2 Instituto Nacional de Tecnologia Industrial - INTI - Buenos Aires/Argentina; 3 Universidade Federal de São Carlos
doi:10.20906/CPS/COB-2015-1167
Resumo
Corrosion of metals is, in the wide variety of the cases, a natural process which leads to deterioration of their mechanical properties. Failures by corrosion cause economic losses and can have safety impact. Corrosion costs are of the order of 3.5% of gross national product of industrialized countries. Degradation of a metal piece can be accelerated by corrosion associated with mechanical forces. Some examples are: stress-corrosion-cracking (SCC); fretting-corrosion; erosion - corrosion and cavitation. Service in life is shortened when comparing with that due only to corrosion or mechanical causes of failures. Erosion - corrosion and cavitation can be minimized by the application of coatings of high resistance to plastic deformation. In this case, the mechanical force (e.g. impingement of solid particles on the surface of the piece) could be less effective in expose the free-surface of the metal to the aggressive environment. Coatings of metal-matrix-composites (MMCs), where the disperse phase consists of hard particles, can be adequate for protecting metal pieces from erosion - corrosion or cavitation. This is due to the combination of ductility and corrosion resistance of the metal matrix with the hardness of dispersed phase (e.g. abrasive particles of SiC, Al2O3, B4C, etc.). In the present work, they were presented the results for the obtainment by electrodepositon of MMCs coatings consisting of CuZn-SiC and their mechanical, chemical and physical characterization. CuZn (brass) possesses good corrosion resistance and SiC are abrasive hard particles. The mean diameter of SiC particles lies in the micrometric range (9.5 µm). It is shown that these composite coatings were successfully obtained by electrodepositon from alkaline cyanide-free solutions with sorbitol as complexing agent. SiC particles were embedded in the CuZn matrix. The surface morphology of the composites, however, was coarser than pure CuZn and the weight percentage of Cu was increased in the composite coatings. The microhardness of the coatings
Palavras-chave: CuZn-SiC; electrodeposition; alkaline sorbitol solution; mechanical properties; metal-matrix composite coatings