“Evaluation and characterization of anticorrosive behavior of some new eco-friendly pigment alternatives in surface coatings”

Abstract

The present thesis is summarized into three main sections as follow; • In the first section, a brief introduction was given on corrosion and the methods of metal protection. Also, this section includes an introduction about coating in general, organic coating in specific and their composition. This part focused on anticorrosive pigments which were prepared by new technique known as core-shell technique. Moreover, core-shell concept, ferrites as shell, (kaolin & silica) as core were explained. • The second section includes materials used in this study, methods of the pigments preparation, evaluation of the prepared pigments and formulation of coatings. Also, methods of the instrumental analysis and the effect of the prepared pigments on the mechanical properties of paints and corrosion inhibition of paint films according to ASTM. • The third section includes results and discussion, and it was divided into three parts. Part I contains the characterization of ferrite and core-shell (Fe/K &Fe/Si) using XRD, TEM, SEM, EDAX, XRF and TGA were used. The results of these analyses proved that the formation of the ferrite shell was according to the ratio 20-15% on core which comprises 80-85% of the pigments chemical structure. These pigments can be considered economically feasible, because their cores which are either natural ore or waste material comprise their major constituent. Part II includes the physical properties of the prepared pigments. Specific gravity, oil absorption, pH, and bulking volume were measured according to ASTM. • Specific gravity of the prepared pigments can be ordered as; ZnFe > CaFe > SrFe K > ZnFe/K > SrFe/K > CaFe/K Si > CaFe/Si > SrFe/Si > ZnFe/Si • Also, oil absorption of ferrite and core-shell (Fe/K & Fe/Si)can be arranged as; CaFe > SrFe = ZnFe CaFe/K > K > SrFe/K > ZnFe/K Si > CaFe/Si > SrFe/Si > ZnFe/Si • pH of the different pigments are as follow; SrFe > CaFe > ZnFe SrFe/K > CaFe/K > ZnFe/K = K SrFe/Si > CaFe/Si = Si > ZnFe/Si

Part III: application of the prepared pigments in two types of resin (e.g. alkyd and epoxy resins) was explained in this part. • Anti-corrosive alkyd based paint formulations were divided into three groups; each has different pigment/binder ratio (P/B), the ratios are as follow; group I has P/B =1.77, group II has P/B = 2.175 and group III has P/B = 3. Also, anticorrosive epoxy based paint formulations were divided into three groups with the same P/B as in case of alkyd-based paints for comparison. a. Study of corrosion protection of alkyd based paint formulations containing the prepared pigments 1. The whole paint formulations containing ferrite pigments have good corrosion protection with good adhesion and low blisters. 2. In Fe/K core-shell pigments, paint formulations of group three was the best and in the three groups CaFe/K > ZnFe/K > SrFe/K > K 3. In Fe/Si core-shell pigments, paint formulations of group two was the best and their corrosion protection can be ordered as; SrFe/Si > CaFe/Si > ZnFe/Si > Si