## 1 Introduction
\[\mathrm{C}_{(s)}+\mathrm{H}_{2}\mathrm{O}\rightleftharpoons\mathrm{C}_{(s)} \mathrm{OH}_{ads}+\mathrm{H}^{+}+\mathrm{e}^{-} \tag{1}\]  
\[\mathrm{C}_{(s)}+\mathrm{OH}^{-}\rightleftharpoons\mathrm{C}_{(s)}\mathrm{OH}_ {ads}+\mathrm{e}^{-} \tag{2}\]  
These radicals immediately react to form hydroxyl, carboxyl, carbonyl or lactone moieties, which are accompanied by an increase in the oxygen content at the carbon surface. The possible functional groups on the graphite surface are shown in Figure 1. Rueffer et al. [8], however, doubt the formation of hydroxyl radicals on the basis of their investigations as an intermediate step and assume a direct incorporation of oxygen into the functionalized groups. The functional groups have different oxidation states and can be further oxidized up to the elimination of carbonates and carbon dioxide [6]. According to Chung [9], these surface oxides have a lower conductivity than non-activated graphitic carbon fibres. Figure 1: Formation of surface oxides in graphite [7]. After activation of the carbon fibre and cleaning of detached carbon fibre fragments, the carbon fibre is always coated in industrial applications [6]. For this, the carbon fibre is passed through a sizing bath filled with a polymer solution or dispersion. However, there are other methods of coating such as electrolytic deposition, electrolytic polymerization and plasma polymerization. As size typically polymer systems are used which have good chemical-physical compatibility for the further use of the carbon fibre. When using epoxy resins, epoxies are used, for example. Other polymer systems include polyhydroxyether, polyphenylene oxides, polysulfones, silanes and cyanamides. The sizing ensures good processability in subsequent processes, good wetting behaviour of the carbon fibre for the impregnation matrix and a strong chemical-physical interaction between these two components for good adhesion. Possible adhesion mechanisms are: mechanical interlocking, secondary bonds, such as London forces and chemical bonds, such as covalent bonds. In the final processing step, the carbon fibres are combined into rovings and impregnated with materials such as epoxy resin matrix or styrene butadiene rubber matrix (SBR). For a good fibre-matrix interaction, a good mixing of the components carbon fibre, sizing and matrix is essential. During the application of the matrix, with \"no release\" of the layer, \"partial release\" or \"complete release\" of the size, there may be three different interphase formations. In the case of complete release, the sizing thoroughly mixes with the matrix, providing the best mechanical properties. The worst mechanical properties are achieved when there is no intermixing between the size and the matrix, that is no detachment. Earlier research [10; 11; 12] has shown that carbon textile is a suitable anode-material for corrosion protection (CP). Various experiments were conducted in order to investigate the behaviour of carbon textiles under anodic polarization. Carbon textiles were tested both in saturated calcium hydroxide solution and in mortar test specimens. It has been found, that the structure of carbon textiles itself is not affected by anodic polarization. However, sizing and impregnation materials suffer considerable destruction in some cases. Asgharzadeh et al. [12] investigated the durability of impregnated carbon textile under permanent anodic polarization while stored in saturated calcium hydroxide solution. Carbon textile was potentiodynamically polarized in saturated calcium hydroxide solution. Starting with the open circuit potential, the applied potential was increased at a constant rate of 2 mV per minute until an overall potential shift of 2200 mV in anodic direction was achieved. Based on the obtained current-density versus (compensated) potential curves, three potentials were selected, which indicate changes in the carbon textiles' electrochemical properties. Potentiostatic tests were performed with the identified potentials.