Abstract
This paper presents the application of the Taguchi experimental design in developing nanostructured yittria stabilized zirconia (YSZ) coatings by plasma spraying process. This paper depicts dependence of adhesion strength of as-sprayed nanostructured YSZ coatings on various process parameters, and effect of those process parameters on performance output has been studied using Taguchi's L16 orthogonal array design. Particle velocities prior to impacting the substrate, stand-off-distance, and particle temperature are found to be the most significant parameter affecting the bond strength. To achieve retention of nanostructure, molten state of nanoagglomerates (temperature and velocity) has been monitored using particle diagnostics tool. Maximum adhesion strength of 40.56 MPa has been experimentally found out by selecting optimum levels of selected factors. The enhanced bond strength of nano-YSZ coating may be attributed to higher interfacial toughness due to cracks being interrupted by adherent nanozones.
Highlights
Increased operating temperatures and improved performance of gas turbines or diesel engines can be realized by using thermal barrier coatings (TBC) [1,2,3,4,5,6]
Plasma sprayed thermal barrier coatings based on yttrium stabilized zirconia (YSZ) have been applied to hot section components
YSZ is the current industrial standard material of TBCs, owing to its low thermal conductivity, phase stability at relatively high temperatures, a relatively high coefficient of thermal expansion (CTE), and chemical inertness in combustion atmospheres as compared to other ceramics [7,8,9,10,11]
Summary
Increased operating temperatures and improved performance of gas turbines or diesel engines can be realized by using thermal barrier coatings (TBC) [1,2,3,4,5,6]. Plasma sprayed thermal barrier coatings based on yttrium stabilized zirconia (YSZ) have been applied to hot section components. Thermal spray coatings obtained from nanostructured powders (as shown in Figure 1) exhibit such outstanding properties. Studies related to identification and quantification of phase transformations in plasma sprayed YSZ coatings have been done [17,18,19]. All process parameters need to be understood, so as to undertake appropriate steps in the design of substrates and coating materials [21]. As the number of such process parameters is too large, statistical techniques could be employed for identification of significant process parameters for optimization In this context, Taguchi experimental design offers an excellent tool for optimizing the total cost without compromising the performance output.
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