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2761 |
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Thursday, September 29, 2011, Saal C2.1 2:00 PM Corrosion Protection 2 |
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Corrosion and wear resistance of molybdenum containing arc spray composite coatings |
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Jussi Laurila* / Tampere University, Finland Juha Vajala / Andritz Oy, Finland Kari Niemi/ Tampere University of Technology, Finland Petri Vuoristo/ Tampere University of Technology, Finland |
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In arc spraying process it is possible to use feedstock wires of two different compositions at the same time. As a result of such a procedure composite coatings with modified physical properties can be prepared. In the present study nickel and cobalt based alloy materials were arc sprayed with a pure molybdenum wire to modify the corrosion and wear resistance of these materials. Coatings for these tests were sprayed using two different arc spray processes. Microstructures of the coating materials were studied and analyzed from cross-sectional specimens by using scanning electron microscopy and EDX analysis. Volume fraction of pure molybdenum in the coating matrices was evaluated with a simple line method from the cross-sectional specimens. Wear resistance was measured with rubber wheel sand abrasion wear test. Corrosion resistance was studied at low pH values and a chlorine containing electrolyte using the ASTM G48 corrosion testing standard. Corrosion testing was carried out at the room temperature and at the temperature of 50ºC. According to the results, volume fraction of molybdenum was higher than 50% in all of these composite coatings. Molybdenum addition was found to improve the abrasion wear resistance of the studied coating systems. At the room temperature also the corrosion resistance was improved with a molybdenum addition, but in higher temperatures no differences was found between the plain and molybdenum containing coatings. |