Abstract
The paper presents the computational studies of microstructure- and topography- related features of suspension plasma sprayed (SPS) coatings of yttria-stabilized zirconia (YSZ). The study mainly covers the porosity assessment, provided by ImageJ software analysis. The influence of boundary conditions, defined by: (i) circularity and (ii) size limits, on the computed values of porosity is also investigated. Additionally, the digital topography evaluation is performed: confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM) operating in Shape from Shading (SFS) mode measure surface roughness of deposited coatings. Computed values of porosity and roughness are referred to the variables of the spraying process, which influence the morphology of coatings and determines the possible fields of their applications.
Highlights
The paper aims at demonstrating the computational methods of image analysis, including porosity, morphology and topography assessment of plasma sprayed coatings.Currently, one of the most extensively studied deposition methods is suspension plasma spraying (SPS)
An innovative approach of this paper is to study the relationships between the mentioned parameters by computational means
When comparing the average pore size, depending on the limited size and applied magnification (Table 3.), it is observed that: (i) in each case, the computed results agree with restricted sizes. (ii) It is not possible to detect and measure the coarse pores (> 10 μm) when using higher magnification (× 8000), so for the assessment of coarse pores, the lower magnification is recommended. (iii) It is recommended to distinguish the range of analysed pores, otherwise the analysis provides more inaccurate results
Summary
One of the most extensively studied deposition methods is suspension plasma spraying (SPS). The method originates from conventional atmospheric plasma spraying (APS). SPS was developed in order to spray fine-grained powders that cannot be deposited by APS. SPS is a very versatile technique (applied amongst others in energy, aerospace, mechanical and petrochemical industries) and provides a variety of coating microstructures [1,2,3]. On the other hand, the final coating’s properties are highly dependent on the deposition parameters. APS spraying is already known to have 50 variables [4], but SPS method is even more complex (for example, the suspension properties highly influence process characteristics) [5,6,7,8]. In this work, two types of SPS coatings with different microstructures (porous and dense) are investigated
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