Ivan Stojanović

Coating Distribution Depending on Surface Microgeometry

Abstract This paper investigates the effects of surface microgeometry on coating thickness, both theoretically and experimentally. In the theoretical part of the paper, surface roughness parameters are analyzed and basic definitions and general requirements on coating quality defined. The experimental part of the paper gives a calculation for the coating quantity required in order to fill “dead volume” depending on surface roughness. Coating distribution is analyzed using scanning electronic microscopy (SEM). The paper also evaluates quality of a measuring system using magnetic method for measuring coating thickness.

Dependence of steel workpiece corrosion rate on the emulsion concentration for machining

Abstract In todays manufacturing, the emulsions for cooling and lubricating are an extremely important and necessary factor for the performance of machining processes. Depending on their composition, properties and production, emulsions in metal cutting operations have various technology functions such as lubricating the surfaces of the tools, facilitating the process of deformation of the cut layer, improving the quality of machined surface as well as cooling the tool and workpiece by removing the part of the heat created by deformation and friction. Corrosion protection of workpieces and tools during and after treatment is also one of the important functions of technological emulsions for cooling and lubricating. In this paper the effects of different concentrations of three emulsions on the corrosion rate of steel workpieces is reported. The results indicate that a higher concentration of emulsion does not provide better protection against corrosion.Abstract In todays manufacturing, the emulsions for cooling and lubricating are an extremely important and necessary factor for the performance of machining processes. Depending on their composition, properties and production, emulsions in metal cutting operations have various technology functions such as lubricating the surfaces of the tools, facilitating the process of deformation of the cut layer, improving the quality of machined surface as well as cooling the tool and workpiece by removing the part of the heat created by deformation and friction. Corrosion protection of workpieces and tools during and after treatment is also one of the important functions of technological emulsions for cooling and lubricating. In this paper the effects of different concentrations of three emulsions on the corrosion rate of steel workpieces is reported. The results indicate that a higher concentration of emulsion does not provide better protection against corrosion.

Crevice corrosion resistance of high alloyed materials in 3.5 % NaCl solution

Abstract The effects of applied torque on the corrosion behaviour of W.-Nr. 1.4404 and 1.4462 stainless steels and W.-Nr. 2.4605 and 2.4858 nickel alloys with crevices were investigated using the cyclic potentiodynamic polarization method. Crevice corrosion (material-to-polytetrafluoroethylene) was tested in 3.5 % NaCl solution at 22 °C. The corroded surface was examined using scanning electron microscopy. The results indicate similar trends in susceptibility to crevice corrosion with increasing torque. Among the four specimens, the W.-Nr. 1.4404 is the most susceptible to crevice corrosion.

Properties of aluminium coatings produced using manual and robotized flame spraying processes

Abstract Aluminium coatings applied using arc or flame spraying processes are frequently employed for protection of steel structures in maritime applications. Results of comparative testing of aluminium coatings produced by manual and robotized flame spraying on steel substrate are reported in the contribution. Particular attention during the investigation of coating properties has been given to the uniformity of coating thickness, adhesion and corrosion resistance. Analysis of the results yielded conclusions on the quality, adhesion and corrosion resistance of the aluminium coating when the coating is applied to the flat steel plate.

Experimental study of imidazoline as an inhibitor of carbon steel in acid media

Abstract The electrochemical behaviour of a carbon steel in deaerated acid media with concentrations of 20 ppm, 50 ppm, 100 ppm and 200 ppm imidazoline at different temperatures and with different stirring rates has been evaluated by using anodic and cathodic polarization curves (Tafel) and electrochemical impedance spectroscopy (EIS) to compare the corrosion inhibition efficiency. The experimental results suggest that imidazoline is a good corrosion inhibitor at 50 ppm concentration.