Sealing porous anodic layers on AA2024-T3 with a low viscosity benzoxazine resin for corrosion protection in aeronautical applications.

In this paper, a 4-ethylphenol--phenylenediamine (4EP-PDA) benzoxazine has been applied and cured on previously anodized AA2024-T3 substrates. The porous surface oxide layers obtained from sulfo-tartaric anodizing appeared to be highly impregnated by the benzoxazine resin, sealing the anodic films. Through rheological, morphological and chemical characterization, the curing process has been identified to be the key step for the impregnation to occur, related to the low viscosity of the 4EP-PDA benzoxazine attained during thermal curing.

Optical Fibre NO₂ Sensor Based on Lutetium Bisphthalocyanine in a Mesoporous Silica Matrix.

In this article, we describe a NO₂ sensor consisting of a coating based on lutetium bisphthalocyanine (LuPc₂) in mesoporous silica. The sensor exploits the absorption spectrum change of this material which strongly and reversibly decreases in contact with NO₂. NO₂ is measured by following the amplitude change in the reflected spectrum of the coating deposited on the tip of a silica fibre.

High-refractive-index transparent coatings enhance the optical fiber cladding modes refractometric sensitivity.

The high order cladding modes of standard single mode optical fiber appear in quasi-degenerate pairs corresponding to mostly radially or mostly azimuthally polarized light. In this work, we demonstrate that, in the presence of a high-refractive-index coating surrounding the fiber outer surface, the wavelength spacing between the orthogonally polarized cladding modes families can be drastically enhanced. This behavior can be advantageously exploited for refractometric sensing purposes.