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5480 |
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Wednesday, June 07, 2017, Hall 27 3:00 PM Suspension Spraying I |
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Suspension plasma spray with ethanol and water based suspensions |
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Francesco Bozza / Turbocoating S.p.a., Italy Nelso Antolotti / Turbocoating S.p.a., Italy Luca Tagliaferri/ Turbocoating S.p.a., Italy Simone Bursich/ Turbocoating S.p.a., Italy Enea Ghidini/ Turbocoating S.p.a., Italy Omar Ligabue*/ Turbocoating S.p.a., Italy |
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Suspension Plasma Spray (SPS) is a more recent development of traditional Air Plasma Spray (APS) technologies. Conventional APS utilizes a powder feedstock material that has an average size in the tens to hundreds of microns. The conventional powder based thermal spray processes are limited in that powders finer than 5 micron in size which cannot be reliably processed. SPS differs in that the powder feedstock is suspended within a solvent such as water or ethanol. The solvent acts as a carrier medium, enabling fine powder to be transported and injected into the plasma stream for processing. Powders used can range in size from tens of nanometers to several microns in size. The fine scale of the powder particles used in SPS allows for a greater range of coating microstructures to be produced than is possible with conventional thermal spray techniques. Of particular interest is the possibility to generate columnar microstructures using SPS technology, especially in the field of Industrial Gas Turbine (IGT) application that can imitate those produced by the established processes. Recent works demonstrated the higher thermal shock resistance of SPS TBCs than conventional coatings. The best performing suspension type (water based or alcohol based suspensions) is however under discussion. The aim of the present work was to test and compare different type of microstructures applied by SPS with both Water and Alchol based media in order to identify the main differences of the final coatings in terms of thermal shock resistance and high temperature behaviour. Moreover, the best performing coating was applied over real components, optimizing the parameters from the lab scale to real parts. Optical microscopy and scanning emission microscopy were used to evaluate the microstructure of the coating across the entire component |