Angela Caprì

Corrosion Resistance of Cerium Based Silane-Zeolite Coatings on AA6061 Alloy

In the present work we analyzed the anti-corrosive properties, on AA6061, of sol-gel silane-zeolite hybrid coatings doped with cerium nitrate ions as inhibitor. Three different types of composite coatings were prepared by using cerium doped zeolite and/or silane matrix. For each type, four formulations, varying the zeolite amount (in the range 60-90% wt), were tested. All composite coating evidenced a high homogeneity and good adhesion performances. Cerium addiction in the coating formulation did not compromise the hydrophobic properties of the coating. Furthermore the addition of the cerium ions improved the anti-corrosion properties of the composite films inducing a significant stability of the electrochemical behavior.

Enhancement of the hydrophobic and anti-corrosion properties of a composite zeolite coating on Al6061 substrate by modification of silane matrix

Anti-corrosion properties of a silane–zeolite composite coating applied to aluminium substrates have been investigated. The composite film was prepared with different silane matrix formulations (varying bi-functional and tri-functional silane ratios). The results showed high hydrophobicity of the modified silane–zeolite coatings. Corrosion protection performance, during immersion in 3.5% NaCl solution, was evaluated by means of polarisation and electrochemical impedance spectroscopy tests. The polarisation curves evidenced a good corrosion resistance of all composite coating; though at high content of bi-functional silane, a reduction of corrosion protection performance was observed. At long immersion time (until 150 days), only the composite coating with low amount of bi-functional silane still evidenced good barrier properties.

Assessment of hydrophobic and anticorrosion properties of composite silane–zeolite coatings on aluminum substrate

The effect of matrix compounds on the behavior of silane–zeolite composite coatings on a 6061 aluminum alloy was evaluated by electrochemical test performed at long immersion time in 3.5% NaCl solution. It was observed that silane chains influence the hydrophobic behavior and the electrochemical performances of the zeolite-based composite coating. All composite coatings showed a long-term protection action in 3.5% NaCl solution. The use of silane compounds with long alkyl chain or with bi-hydroxyl groups made it possible to obtain electrochemically stable coating during long immersion time. Best results have been obtained with a multicomponent silane mixture (short and long molecular chains).

Electrochemical Impedance Spectroscopy Behaviour of NdFeB Coated Magnets in Saliva Solution for Orthodontic Applications

In this work the assessment of the corrosion performances in saliva solution of NdFeB magnets coated with silane layers was studied for its application in orthodontic brackets. The silane film, deposited by dip coating technique, has been prepared with varying dipping steps, with the purpose to identify the number of layers able to achieve an optimal protective action. Corrosion protection performance, during immersion in Fusayama synthetic saliva solution, was evaluated by means electrochemical impedance spectroscopy (EIS). The silane coatings evidenced good barrier properties resulting in an improvement of the anti-corrosion performances of the magnets. Better results were observed for samples with at least 15 layers of silane, that evidenced still acceptable protective action after three days of immersion in a Fusayama synthetic saliva solution.

New Functional Composite Silane-Zeolite Coatings for Adsorption Heat Pump Applications

The adsorption heat pumps represent an innovative technology to increase the efficiency of thermal energy. To date, this technology requires in-depth analysis in order to increase the overall performance of the equipment. In this context, it is necessary to increase the overall performance of the equipment. The development of multifunctional adsorbent coatings is an important design solution to improve engineering and technology of adsorption heat pumps. Thanks to the use of adsorbent coatings, the heat exchangers and heat pumps can operate more efficiently. These coatings must not only be effective in terms of energy efficiency (thermodynamic and kinetic adsorption properties) but also in terms of mechanical and electrochemical stability. This chapter shows how this problem could be managed through the use of innovative multifunctional composite silane-zeolite coatings. The method proposed in this chapter is based on the deposition, using a hybrid silane binder, of the adsorbent material based on aluminum zeolite. The chemical-physical-mechanical characterization of the composite materials with the purpose to evaluate its industrial applicability is discussed. In particular, adhesion, hydrophobicity, and durability tests were performed. This chapter also highlights how different types of matrices can affect the performance of the coating. The results obtained showed that the performances of the coating were closely related to the interaction between zeolite filler and silane matrix. Furthermore, the type of matrix was an important variable in order to optimize the properties of the composite coating up to its use in the commercial field.

Corrosion Behaviour of a Silane Protective Coating for NdFeB Magnets in Dentistry

The corrosion behavior of coated and uncoated Ni/Cu/Ni rare earth magnets was assessed at increasing steps with a multilayering silanization procedure. Magnets’ durability was analyzed in Fusayama synthetic saliva solution in order to evaluate their application in dental field. Corrosion performance was evaluated by using polarization and electrochemical impedance spectroscopy in synthetic saliva solution up to 72 hours of continuous immersion. The results show that the addition of silane layers significantly improved anticorrosion properties. The coating and aging effects, in synthetic saliva solution, on magnetic field were evaluated by means of cyclic force-displacement curves.