Experimental visualization of microstructure evolution during suspension plasma spraying of thermal barrier coatings

• This paper investigates the evolution of microstructure of thermal barrier coatings (TBCs) produced by suspension plasma spraying (SPS) through a careful experimental study. Understanding the influence of different suspension characteristics such as type of solvent, solid load content and median particle size on the ensuing TBC microstructure, as well as visualizing the early stages of coating build-up leading to formation of a columnar microstructure or otherwise, was of specific interest. Several SPS TBCs with different suspensions were deposited under identical conditions (same substrate, bond coat and plasma spray parameters). The experimental study clearly revealed the important role of suspension characteristics, namely surface tension, density and viscosity, on the final microstructure, with study of its progressive evolution providing invaluable insights. Variations in suspension properties manifest in the form of differences in droplet momentum and trajectory, which are found to be key determinants governing the resulting microstructure (e.g., lamellar/vertically cracked or columnar).

Ämnesord

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

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

Nyckelord

Suspension plasma spraying

Thermal barrier coatings

Droplet momentum

Columnar microstructure

Microstructure evolution

Manufacturing and materials engineering

Produktions- och materialteknik

Production Technology

Produktionsteknik

Publikations- och innehållstyp

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