Abstract No.:
4725

 Scheduled at:
Wednesday, May 11, 2016, Room 3H + 3I + 3J 4:00 PM
Arc Spraying & Laser Spraying


 Title:
Effect of traverse speed on residual stress distribution and cavitation erosion behavior of arc sprayed aluminum bronze coatings

 Authors:
Michél Hauer* / Fraunhofer Institute for Large Structures in Production Engineering IGP, Thermal Joining Engineering, Germany
Sebastian Krebs / Helmut-Schmidt University, University of the Federal Armed Forces, Germany
Werner Krömmer/ Linde AG, Linde Gases Division, Germany
Knuth-Michael Henkel/ Fraunhofer-Application Center for Large Structures in Production Engineering, Germany

 Abstract:
Severe erosion on modern containerships and ferries travelling with higher speeds endangers ship operation. One main factor is cavitation erosion, which is the formation and collapse of vapour bubbles caused by pressure oscillations. Areas exhibiting high material loss by cavitation erosion require expensive repairs by means of build-up welding and additional grinding work. Although thermal spray technologies like arc spraying are promising solutions for fabricating cavitation erosion resistant coatings, even in dry dock, they are not in use in the marine industry yet. One reason is the lack of knowledge concerning the influence of residual stress distribution on mechanical properties and coating adhesion. Those stresses result from complex superposition of quenching, cooling and other stresses generated during the spray process. Previous studies revealed that when residual stresses are accompanied by external stresses or coatings exceed a certain thickness, coating delamination occurs and thus significantly reduces service lives. Cohesive and adhesive properties in combination with residual stresses of arc sprayed coatings are strongly influenced by materials, spray parameters and heat transfer in substrate and coating.
In the work presented, arc spraying was used with different traverse speeds to influence the heat transfer and hence the stress state. The residual stress distribution was measured by modified hole-drilling method using ESPI. Further microstructural, chemical and mechanical analyses were realized to examine adhesive and cohesive properties. The materials used for spray experiments were the highly cavitation erosion resistant propeller alloys CuAl9Ni5Fe4Mn2,5 and CuMn13Al8Fe3Ni2. Finally, analyses of cavitation erosion behavior were carried out to evaluate the suitability for use in marine environments. The results of the study enable a selective adjustment of the spray parameters to a stress state which is suitable to the load.


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