Abstract

The use of a scanning electron microscope in low vacuum mode (or reduced pressure) permits to obtain secondary electron images of specimens that are non-conductive or specimens which have not been coated with a conductive material such as gold or carbon. This technique is advantageous for the observation of specimens like biological samples, moist samples, liquids, polymers and ceramics among others [1]. Unlike high vacuum mode (HighVac), the regime pressure of the low vacuum mode (LowVac) stands in the range of 10 to 130 Pa which assist to eliminate the effects of charge accumulation onto the surface and preserve fragile structures (biological samples) as well. The use of this mode of observation to the study of glass-ceramic spherical materials has been evaluated. Also this material was observed applying the HighVac mode in order to compare viewing conditions between both observation modes. The spherical material is obtained from crystalline blast furnace slags (BFS) generated by steelmaking industry [2]. The process involves a natural gas/oxygen thermal projection process and conversion of the BFS precursors into glass-ceramic spheres. The study and characterization of the new glass-ceramic spherical particles is required because their chemical properties depend on the morphology, finally these materials can be incorporated into specific cementing slurries formulation as lightweight aggregates and is expected that they will improve the thermal and acoustic isolation properties of the final concrete and/or cement systems. This study has demonstrated that the use of the LowVac mode is adequate to study the morphology of these structures over the HighVac mode, besides allowed to set operating parameters in order to obtain images with free-charge accumulation.