M. Delucchi, S. Turri, A. Barbucci, M. Bassi, S. Novelli, G. Cerisola
Barrier properties of fluoropolyether coatings: relationships between eis measurements and polymer structure
Journal of Polymer Science, Part B-Polymer Physics 40 (2002) 52-64

ABSTRACT
Ten model coatings, selected and obtained from of a family of fluorinated resins synthesized by reacting perfluorother oligomeric diols of different molecular weight with polyisocyanurates of hexamethylenediisocyanate (HDI) and isophoronediisocyanate (IPDI), were characterized through Differential Scanning Calorimetry (DSC), Mechanical Testing and Electrochemical Impedance Spectroscopy (EIS) measurements. The electrochemical and chemico-physical measurements showed that the glass transition temperature of the starting isocyanate trimers highly influences the properties of the final urethane coatings; the IPDI trimer gives harder coatings, with lower water permeabilities than the corresponding HDI based materials. Moreover, considering each class of materials (from IPDI or HDI), the fluorine content plays a relevant role: the higher the fluorine percentage, the lower the water absorption into the coatings. Furthermore, the chain length of the polyols used for the synthesis of the prepolymers is a variable which exhibits great influence on the coating properties: coatings containing shorter PFPE segments show better barrier properties.

C. Bocca, A. Barbucci, M. Delucchi, M. Lechi, G. Cerisola
Determination of the electrochemical characteristics of traditional and innovative antifouling paint systems by impedance measurements
Pitture e Vernici Europe 78 (2002) 7-11

A. Barbucci, R. Bozzo, G. Cerisola and P. Costamagna
Characterisation of composite SOFC cathodes using electrochemical impedance spectroscopy. Analysis of Pt/YSZ and LSM/YSZ electrodes
Electrochimica Acta 13-14 (2002) 2183-2188

ABSTRACT
The performance of composite electrodes as a function of the electrode composition is investigated experimentally through electrochemical impedance spectroscopy (EIS). In particular, two different composite cathodes are analysed, i.e. Pt/YSZ and LSM/YSZ. Typical impedance spectra have been obtained and used to evaluate the overall electrode polarisation resistance Rp. The qualitative features are similar for both cathodes; in particular, in both cases the electrode performance (expressed in terms of Rp-1) shows a dome-shaped curve as a function of the electrode composition. Nevertheless, the quantitative aspects are very different; in particular, the maximum value of Rp-1 is much higher for the LSM/YSZ electrode than for the Pt/YSZ one (22 vs. 1.5 S cm-2). Also, the composition which gives the maximum performance and the experimental values of the percolation thresholds are different. The reasons for the discrepancies are analysed and discussed.

M. Delucchi, S. Turri, A. Barbucci, S. Novelli and G. Cerisola
Investigation on physico-chemical and electrochemical properties of fluoropolyether coating
Progress in Organic Coatings 44 (2002) 227-232

ABSTRACT
A series of model coatings made of perfluoropolyether (PFPE) and different isocyanurate blocks were prepared and investigated through differential scanning calorimetry (DSC), dynamic-mechanical analysis (DMA) and electrochemical impedance spectroscopy (EIS) measurements. Phase transitions, dielectric constants and water permeability were also evaluated. The result was that the molecular weight of PFPE segment as well as the chemical nature of isocyanurate block influence the properties of the final urethane coatings. In general, polyphasic polyurethane networks are formed, but in some cases more homogeneous structures are promoted by the use of low molecular weight PFPE segments. Lower water permeabilities are obtained by the higher Tg and harder IPDI containing coatings. Very efficient barrier behaviour even at long exposure are shown by coatings made with lower molecular weight PFPE macromers.

M. Delucchi, A. Barbucci, T. Temtchenko, T. Poggio and G. Cerisola
Study of the crack-bridging ability of organic coatings for concrete: analysis of the mechanical behaviour of unsupported and supported films
Progress in Organic Coatings 44 (2002) 261-269

ABSTRACT
The interest in using organic coatings to protect concrete structures has increased rapidly in recent years. One of the main parameters requested of these films for protecting structures is that they maintain their integrity even if the underlying concrete cracks. In this paper, a technique to evaluate the crack-bridging ability (CBA) of the coatings is addressed. In addition, the CBA of different organic coatings is analysed on the basis of the mechanical behaviour of the unsupported films during stress¯strain measurements. Experimental results suggest a power law relationship between CBA and the tensile strength of the coating.

P. Costamagna, M. Panizza, G. Cerisola, A. Barbucci
Effect of composition on the performance of cermet electrodes. Experimental and theoretical approach
Electrochimica Acta 47 (2002) 1079-1089

ABSTRACT
This work aims to analyse the behaviour of cermet electrodes as a function of their composition, i.e. the ratio between ionic and electronic conducting particles. This is an important parameter to be considered to obtain maximum performance from this type of electrode, which is currently under study for application in oxygen sensors and solid oxide fuel cells. Experimental results of overall electrode resistance, including both ohmic and activation polarisation effects, have been obtained through electrochem-ical impedance spectroscopy measurements of Pt/YSZ electrodes in air. The results compare favourably with the theoretical predictions for several compositions above the percolation threshold of the electronic conductor. For this reason, the model is a useful tool for the design of optimised cermet electrodes; in particular, the experimental data show that maximum performance is attained for compositions very close to the percolation threshold of the electronic conductor, and this is in very good agreement with the modelling results.

A. Barbucci, G. Cerisola, P.L. Cabot
Effect of Cold Working in the Passive Behavior of 304 Stainless Steel in Sulfate Media
Journal of The Electrochemical Society 149 (2002) B534-B542

ABSTRACT
Extra-low sulfur cold rolled 304 stainless steel samples, annealed and cold worked to different degrees in an industrial plant, together with a ferrite-rich SS, have been studied by electrochemical and microscopical techniques to analyze the effect of cold working on its passive behavior in sulfate media. The techniques employed were potentiostatic and cyclic polarization, optical microscopy, transmission electron microscopy, X-ray diffraction, ex-situ scanning tunneling microscopy, and ex-situ and in-situ atomic force microscopy. The cyclic polarization measurements showed that the passive currents in neutral sulfate+chloride and in sulfuric acid solutions were very similar, and increased with cold work. The pitting susceptibility also increased with cold work, this effect being more evident as the chloride concentration increased. The dependence of the pitting potential on cold work was explained using the bilayer model, the sulfate ingress in the passive film during anodic oxidation forming a coulombic barrier against chloride penetration. The microscopic examination of the samples after long time polarization in 1.0 M sulfuric acid showed that the surface profile of the passive film depended on the metallurgical structure of the metallic substrate. The higher passive currents and the increased susceptibility to pitting corrosion of the work hardened samples were explained by the formation of a much more defective oxide during its anodic oxidation, with easy paths that enhanced sulfate ingress. The growth of such a much more imperfect oxide was related to the formation of defects in the grains and of more defective interfaces in the bulk of the material, both resulting from the accumulation of internal stresses, during cold rolling. Comparison with previous work highlighted the role of such defects in front of the absolute amount of martensite in the material.

M. Delucchi, C. Pagella, G. Cerisola
Laboratory testing of intumescent coatings for steel protection
Protective Coatings Europe 7 (2002) 17-21
Journal of Protective Coatings and Linings 19 (2002) 65-71