ABSTRACTIn recent years, due to their high specific mechanical properties, the polymer matrix composites have been widely used. In particular, carbon nanotubes (CNTs) have been used as reinforcement due to its exceptional mechanical and electrical properties. In this work the mechanical behavior of polyvinyl alcohol (PVA) reinforced with different percentages of mechanically oriented CNTs was studied. The composite material was made starting with a solution of PVA+ distilled water, and then the CNTs were added to the solution and dispersed by magnetic stirring and ultrasonic agitation. During this step, a surfactant was added to help with the CNTs dispersion. This mixture was poured into a container and dried using a heat source to accelerate its polymerization and curing. The layers obtained were subjected to mechanical stretching at controlled temperature to align the CNTs in the loading direction. The mechanical properties were measured by tensile testing and nanoindentation. The results show a large increase in modulus and hardness compared with non-reinforced polymeric material, it was also found a significant increase in the tensile strength. The composite with the best properties was subjected to thermal stabilization by ethanol, obtaining an increase in the degradation temperature of about 100°C approximately, although in this case the mechanical stiffness and hardness were decreased compared to unstabilized material, the usefulness of this material is enhanced.

Los recubrimientos de aluminio depositados sobre el acero inoxidable austenítico AISI 317 por Deposición Química de Vapor en Lecho Fluidizado (CVD-FBR) presentan a altas temperaturas una reducción de la velocidad de corrosión de más de 80 veces. Se realizó la caracterización mecánica de los recubrimientos por medio de microdureza, nanoindentación, para conocer cómo se vieron afectas las propiedades mecánicas (en especial la dureza y el módulo de Young) del recubrimiento y del sustrato luego de ser sometidos a la oxidación a alta temperatura. También se hicieron análisis por medio de Microscopia Electrónica de Barrido (MEB), para observar los cambios microestructurales, y de Microscopia de Fuerza Atómica (MFA), para observar cómo varía la topografía y el gradiente de rugosidad en función de la distancia recorrida por la punta del cantiléver durante los barridos.

The aluminum coatings deposited by Chemical Vapour Deposition Fluidisation (FBR-CVD) on the austenitic stainless steel AISI 317, show a more than 80 times corrosion rate reduction at high temperatures. The coatings mechanical characterization was conducted by means of microhardness, nano indentation, in order to konow how were affected the coating and the substrate’s mechanical properties (particularly the hardness and the Young’s modulus) after being subjected to oxidation at high temperature. Some analyses were also made by means of SEM, to observe the micro structural changes and to see how is the AFM topography and rugosity gradient variation, related to the distance traveled by the tip of the cantilever during the sweeps.

Os recobrimentos de alumínio depositados sobre o aço inoxidável austenítico AISI 317 por Deposição Química de Vapor em Leito Fluidizado (CVD-FBR) apresentam a altas temperaturas uma redução da velocidade de corrosão de mais de 80 vezes. Realizou-se a caracterização mecânica dos recobrimentos por meio de microdureza, nanoindentação, para conhecer como foram afetadas as propriedades mecânicas (em especial a dureza e o módulo de Young) do recobrimento e do substrato após serem submetidos à oxidação a alta temperatura. Também foi feita a análise por meio de Microscopia Eletrônica de Varredura (MEB), para observar as mudanças microestruturais, e de Microscopia de Força Atômica (MFA), para observar como varia a topografia e o gradiente de rugosidade em função da distância recorrida pela ponta do cantiléver durante a varredura.