Multivariate analysis of the process parameters’ influence on suspension plasma sprayed coatings

Suspension plasma spray (SPS) is by far more complicated than conventional plasma spray and requires a deep knowledge about the influence of process parameters and their correlations. In this study, YSZ coatings were manufactured by SPS with different process parameters. Afterwards, the porosity, pore size and mechanical behavior of as-prepared coatings were investigated. The corresponding experimental database includes a wide panel of tests from which it is difficult to extract the key parameters and their correlations. For overcoming this problem, a promising method is reducing the dimension of the large SPS parameter set containing interrelated variables into a more concise set that just retains main variations. Multivariate analyses on the collected experimental data were particularly carried out by employing principal component analysis and factor analysis. Results showed that:

1) Spraying distance is the main factor corresponding to the coating average porosity,

2) The content of small pores (size < 2μm) has a significant negative correlation with the original powder size and suspension mass load and a positive correlation with the substrate roughness,

3) Higher coating porosity results in higher friction coefficient and lower wear resistance,

4) Increasing the small pore content contributes to enhance the wear resistance of the coating.