Adhesion of selected thermally sprayed coatings on additive manufactured maraging steel

Abstract

Additive manufacturing (AM) technology is increasingly expanding into different types of industries. Still, many potential applications are restricted due to the limited choice of materials used in AM. A suitable solution could be a combination of AM and thermal spraying of functional parts of the surface to achieve superior surface properties. This work aims to study the possibility to prepare the surface with AM technology to direct application of coating by thermal spraying without any additional surface preparation. To verify this possibility, the parameters of the 3D printing technology were adjusted to achieve suitable surface structures for the following thermal spraying. Several variants of modifications with different surface properties were selected. The samples were printed from maraging steel using the DMLS technology. The coatings chosen for testing were WC – CoCr and Stellite 6 sprayed by HVOF and further NiAl and Al2O3-TiO2 sprayed by APS. The adhesion of the coating was tested by an adhesion test performed under the ASTM C633-79 standard. The bonding of the coating on the surface was studied by metallographic analysis. The achieved results indicate that the adhesion of HVOF sprayed WC-CoCr coating on 3D printed surfaces is excellent for most surface modifications. The Stellite 6 exhibits good adhesion on several surface modifications. The APS sprayed coating shows significantly lower adhesion, the NiAl and Al2O3-TiO2 coatings can be successfully sprayed only on selected surface modifications.