PSI - Issue 16

Barbara Nasiłowska et al. / Procedia Structural Integrity 16 (2019) 230 – 236 Barbara Nasiłowska et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Surface topography of glass showed that after GO deposition (Fig. 4) increase in roughness was observed for all above parameters as follows: 20, 157, 40, 107 and 15% for Rq, Rp, Rv, Rzi Ra respectively. Graphene oxide deposition on construction steel S235 occurred in decrease of the roughness parameters for about 10, 22, 19 and 11% for Rq, Rv, Rz and Ra respectively as compared to pure, un-deposited steel. Surface corrosion had major influence on roughness parameters. Substantial increase in analysed parameters was observed as follows: 181, 232, 190, 227 and 174% for Rq, Rp, Rv, Rz and Ra respectively as compared to the steel sample not covered with GO (Fig. 5). 3.2. Wettability of graphene oxide Fig. 6 shows the results of the static sessile drop measurements for water and acrylic resin. The measurements were carried on glass, glass with GO, steel S235, steel with GO and steel with corrosion. The major influence concerning GO deposition was observed on glass surface. Before GO deposition glass surface was showing super hydrophilic properties. Before GO deposition contact angle between glass and water was 12°. This state describes maximal wettability of the surface. After GO deposition contact angle has changed and it was recorded as 64° showing shift of the properties of the GO-glass surface toward hydrophilic ones.

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Fig. 6. (a) contact angle changes before and after GO deposition on glass, (b) contact angle changes measured on the steel S235, steel +GO, steel with initiated surface corrosion.

Experimental results of the contact angle of the acrylic resin on each of the examined surfaces showed similar values. Measured angle values were in a range 70 –77°. Such a narrow range of changes is mostly connected with acrylic resin density and viscosity. Contact angle measurement with water showed more diversified results than with acrylic resin. From the group of steel samples only the surface of steel with GO layer showed features of hydrophobicity. Contact angle above 90° indicate hydrophobic features of the surface. This feature is particularly desired in applications when anticorrosive properties are required. GO layers are tested nowadays as potential anticorrosive layers. As compared to glass GO deposition shifted surface character form super hydrophilic to hydrophobic. 3.3. ATR surface analysis Fig. 7a shows histochemical map of the glass+GO surface with acrylic resin drop deposited on its surface. Fig. 7b shows histochemical map of the steel+GO surface with acrylic resin drop deposited on its surface. For histochemical analysis 1614 cm -1 peak was chosen with assignment of both C=O from carboxylic group or carbonyl group originating form oxidized GO layer (Rattana, 2012).