## 4 Conclusions  
In this study, EB-PVD TBC coatings were successfully deposited on bond coats subjected to various roughness treatments. The main conclusion is that the roughness of the bond coat affects the roughness of the 7 YSZ top coat deposited by the EB-PVD method. The lower the roughness of the bond coat, the lower the overall roughness of the ceramic coating. In addition, the columnar structure is correlated with the surface roughness of the bond coat. EB-PVD TBCs prepared on smoother bond coats exhibit a more uniform columnar structure. Therefore, to improve the quality of TBC coatings, the bond coat should be polished before applying the 7 YSZ top coat in the EB-PVD process. However, it was not determined whether the surface roughness of the bond coat affects the adhesion of the 7 YSZ top coat. Nevertheless, it was found that the adhesion strength of thermal barrier coatings produced by the EB-PVD surely exceeds 90 MPa. With the properly treated bond coat, the adhesion of the EB-PVD TBC coating may exceed the 105 MPa obtained in this study. These preliminary results form the basis for ongoing research aimed at evaluating TBC coatings with different current-voltage parameters to verify the impact of bond coat preparation on the functional properties of TBC layers, including the cyclic oxidation resistance. Initial findings indicate that the preparation of the bond coat significantly influences the microstructure of the ceramic top coat, which, in turn, affects its performance characteristics. For instance, smoother bond coats lead to more uniform columnar structures, which can enhance the thermal barrier properties of the coating. This is particularly important for applications in high-temperature environments, such as jet engines and gas turbines, where TBCs are critical for protecting components from thermal degradation. Improved TBC coatings can lead to a longer lifetime and better efficiency of these engines, reducing maintenance costs and improving overall performance. Moreover, understanding the relationship between bond coat roughness and top coat adhesion is crucial for the development of more durable coatings. Although current adhesives used in tensile adhesion tests limit the measurable adhesion strength to 105 MPa, ongoing research aims to develop new testing methods or adhesives that can provide more accurate measurements. This will help to optimise coating processes to achieve the best possible adhesion and durability. Future work will also focus on assessing the impact of bond coat roughness on other properties of the TBC, such as thermal conductivity, resistance to thermal shock, and overall durability. These studies are essential for advancing the technology and ensuring that coatings meet the rigorous demands of industrial applications. In summary, the findings of this study are significant for manufacturers, particularly in the aerospace and energy sectors, where the quality and performance of TBCs can have a profound impact on the reliability and efficiency of the product. By optimising the surface preparation of bond coats, manufacturers can produce superior TBCs that offer enhanced protection and performance, ultimately leading to more efficient and durable engines and turbines. Conceptualisation, G.M. and A.N. ; methodology, G.M. ; software, A.N. ; validation, G.M. and A.N. ; formal analysis, A.N. ; investigation, A.N. ; resources, A.N. ; data curation, A.N. ; writing--original draft preparation, G.M. ; writing--review and editing, A.N. ; visualisation, A.N. ; supervision, A.N. ; project administration, A.N. ; funding acquisition, A.N. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. Data Availability StatementData are contained within the article. The data presented in this study are available in the form of the final report, which pertains to a project associated with an industrial doctorate conducted at Rzeszow University of Technology by [PERSON] under the supervision of [PERSON].