External Hybrid Deposition: A Novel Method for Thermal Spraying of Thermally Sensitive Materials

• Published in: Journal of thermal spray technology 2024-03, Vol.33 (2-3), p.572-582
• Main Authors: Tesar, Tomas, Musalek, Radek, Lukac, Frantisek, Dudik, Jonas
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion and Coatings; Machines; Manufacturing; Materials Science; Original Research Article; Processes; Surfaces and Interfaces; Thin Films; Tribology
• ISSN: 1059-9630; 1544-1016
• DOI: 10.1007/s11666-023-01695-y

Hybrid plasma spraying has been proved to provide novel coating microstructures as a result of the simultaneous injection of a dry coarse powder and a liquid feedstock into the plasma jet. Such microstructure contains both large splats originating from the conventional dry powder and finely dispersed miniature splats deposited from the liquid. This approach enables preparation of coatings from virtually all materials which are conventionally processed using plasma spraying. However, incorporation of materials susceptible to volatilization or decomposition at high temperatures is still challenging even using this concept due to the high thermal energy transferred toward the feedstocks to be deposited. Hereby, an innovative approach of incorporation of thermally sensitive materials into a coating sprayed using a high-enthalpy plasma torch is proposed using so-called external feeding deposition. As a case study, three coarse-powder-based feedstocks (Al 2 O 3 , YSZ, and Cr 2 O 3 ) were complemented with three suspension-based feedstocks (MoS 2, WS 2 , and ZnS, respectively) deposited using the novel method. In all three coatings, the additional thermally sensitive materials were successfully deposited, retaining their original structure and morphology, which was confirmed using scanning electron microscopy and X-ray diffraction.