CoatMat

A protective coating for SiC fiber reinforced borosilicate glass-matrix composites based on zinc borosilicate (ZBS) glass-ceramic was developed. The coating was deposited on the composite surfaces by a simple and cost-effective method, based on slurry dipping followed by a densification and crystallisation stage carried out at optimised temperature and holding time. The coatings were shown to be able to withstand temperatures of up to 700 °C without softening and without exhibiting microcracking.

Premature failure of dies is a critical problem of manufacturers in hot-working processes, e.g. metal die casting, hot extrusion and/or thixoextrusion of aluminium/magnesium or steel. Typically, die material has to be resistant to heat cycling or corrosion environment, to plastic deformation and wear, especially when exposed to high temperature during continuous working cycle. The resistance of dies could be increased by the modification of their surfaces, i.e. by the application of an adequate coating. An improvement of the resistance of H11 steel substrate will be presented and discussed.

A method for the preparation of TiO2 thick films made of anatase nanocrystallites and featuring a mesoporous structure is described. Modification of a typical sol–gel synthesis that uses Titanium (IV) isopropoxide (TTIP) as precursor, through both the incorporation of a non-ionic surfactant (Tween 20) and the optimization of thermal treatments, allows to increase the thickness of each spin-coated layer, and to obtain by successive runs porous, transparent, homogeneous and crackless films with thickness up to 1.2 μm.

UV-cured polysiloxane epoxy coatings containing titanium dioxide were prepared by means of a cationic photopolymerization process. A good distribution of the inorganic filler was achieved within the polymeric network with an average size dimension of around 500 nm. UV-vis analysis performed on organic dye (methylene blue) stained coatings showed a high efficiency of the titania photocatalytic activity: a complete degradation of the dye on the coating surface is reached after 60 min of UV irradiation without affecting the matrix photo-degradation.

Composite and nanocomposite ceramics have achieved special interest in recent years when used for biomedical applications. They have demonstrated, in some cases, increased performance, reliability, and stability in vivo, with respect to pure monolithic ceramics. Current research aims at developing new compositions and architectures to further increase their properties. However, the ability to tailor the microstructure requires the careful control of all steps of manufacturing, from the synthesis of composite nanopowders, to their processing and sintering.

This paper deals with the preparation and characterization of nanocomposite (NC) materials, comparing different technologies for sample fabrication, in view of their possible application as piezoelectric sensors. Those NCs consist on BaTiO3 nanoparticles embedded into a polyvinylidene fluoride matrix, where both the ceramic and the polymeric phases could exhibit ferroelectricity.