Axial Plasma Spraying of Mixed Suspensions : A Case Study on Processing, Characteristics, and Tribological Behavior of Al2O3-YSZ Coatings

• Thermal spraying deploying liquid feedstock offers an exciting opportunity to obtain coatings with characteristics vastly different from those produced using conventional spray-grade powders. The most extensively investigated variant of this technique is Suspension Plasma Spraying (SPS), which utilizes a suspension of fine powders in an appropriate medium. The relatively recent advent of axial feed capable plasma spray systems can enable higher throughputs during SPS, provides the possibility for spraying with longer stand-off distances, and also permit the use of suspensions with higher solid loading. The present work investigates axial plasma sprayed coatings produced using a mixed suspension of fine (submicron or nano-sized) powders of Al(2)O(3)and YSZ as a case study. Deposition of the mixed suspension using axial injection plasma spraying, comprehensive evaluation of characteristics of the resulting coatings, and assessment of their tribological behavior were of particular interest. Evaluation of surface morphology, microstructure, and hardness of the coatings reveals that axial SPS of mixed suspensions provides an exciting pathway to realize finely structured multi-constituent coatings using suspensions with as high as 40 wt.% solid loading. The study of scratch, dry sliding wear, and erosion behavior also specifically shows that the addition of YSZ in the Al(2)O(3)matrix can improve the tribological properties of the coating.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Bearbetnings-, yt- och fogningsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Manufacturing, Surface and Joining Technology (hsv//eng)

Nyckelord

SPS

mixed suspension

axial injection

alumina

YSZ

microstructure

tribological properties

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