Effect of Heat Treatment on Microstructure and Selective Corrosion of LPBF-AlSi10Mg by Means of SKPFM and Exo-Electron Emission.

The paper deals with the evolution of the microstructure of AlSi10Mg alloy obtained by laser powder bed fusion (LPBF), as a function of the post-processing heat treatment temperature. This was approached by complementary methods including FE-scanning electron microscopy, scanning Kelvin probe force microscopy and exo-electron emission techniques. The fast cooling rate of the LPBF process as compared to traditional casting produces a very fine microstructure with high mechanical properties and corrosion resistance. However, the LPBF-AlSi10Mg alloy can be susceptible to selective corrosion at the edge of the melt pools generated by the laser scan tracks. Post-process thermal treatments of the Al alloy induce a marked modification of the silicon network at melt pool edges, in particular at high temperature such as 400 °C. It was found that this is associated to a more homogeneous distribution of Volta potential. Analysis of exo-electron emission confirms the silicon diffusion during thermal treatment. The modification of the silicon network structure of the LPBF-AlSi10Mg during thermal treatment reduces the susceptibility to selective corrosion.

Evaluación de la filtración marginal de diferentes materiales adhesivos en lesiones cervicales: experiencia "in vitro" / An evaluation of the marginal leakage of different adhesive materials in cervical lesions: an in vitro experience

Este estudio evaluó comparativamente, "in vitro", la capacidad de sellamiento marginal de diferentes materiales restauradores adhesivos en lesiones cervicales. Fueron realizadas restauraciones, según las recomendaciones de los fabricantes, con los siguientes materiales: Chelon Fil/ESPE; Variglass/Dentsply; Vitremer/3M y con el sistema adhesivo Scotchbond Multi-Purpose/3M asociado al composite Z100/3M. Los resultados observados fueron sometidos a un análisis estadístico del test de Kruskal Wallis con nivel de significación del 5 por ciento y por el test de comparacioens múltiples. En la pared de esmalte el Variglass presentó diferencia estadísticametne significativa en la mejor capacidad de sellamiento marginal que el Vitremer y que el Scotchbond Multi-Purpose asociado al composite Z100. En la pared de cemento el Vitremer y el Scotchbond Multi-Purpose asociado al composite Z100 presentaron diferencias estadísticamente significativas en el mejor desempeño de sellamiento marginal que el Chelon Fil