Structures and Properties of Laser-Assisted Cold-Sprayed Aluminum Coatings

Abstract

In the cold spray process, solid particles impact on a surface with high kinetic energy, deform plastically and form a coating. This enables the formation of pure and dense coating structures. Even more, coating performance and deposition efficiency can be improved by assisting the process with a laser. Laser-assisted cold spraying (LACS) has shown its potential to improve coating properties compared with traditional cold spraying. In this study, coating quality improvement was obtained by using a co-axial laser spray (COLA) process which offers a new, cost-effective laser-assisted cold spray technique, for high-quality deposition and repair. In the COLA process, the sprayed surface is laser heated while particles hit the surface. This assists the better bonding between particles and substrate and leads to the formation of tight coating structures. This study focuses on the evaluation of the microstructural characteristics and mechanical properties (e.g., hardness and bond strength) of LACS metallic coatings.

Cold-Sprayed Al6061 Coatings: Online Spray Monitoring and Influence of Process Parameters on Coating Properties

“…Substrate material together with the process parameters influenced on the bonding. Earlier, it was noticed that coating adhesion was higher on soft metal substrate compared to harder substrate material [2,38]. Similarly here, adhesion strength of the cold-sprayed Al6061 coatings were higher on the Al substrate (~35 MPa) compared to those on the low carbon steel substrate (~20 MPa), Figure 10.…”

“…In our study, the coating hardnesses were at a similar level as they were in the previous study, where the coatings were sprayed with laser-assisted cold spraying. This indicates possible recovering already during the spraying with the higher process temperature [2]. The coating hardness was ~106 HV0.3, which was slightly higher than the hardness in this study.…”

“…For example, corrosion resistance, electrical conductivity, wear resistance, functional properties, and repairing possibilities are application fields for cold-sprayed coatings. Especially, for corrosion protection and repairing possibilities, Al and Al-based alloy coatings have received a lot of interest due to their good material properties and high suitability for cold spraying as the feedstock materials [1][2][3][4][5]. In cold spraying, low melting point materials such as Al alloys can be sprayed without oxidation.…”

“…Al6061 is a precipitation-hardened Al-based alloy, which has Mg and Si as major alloying elements [30]. Earlier, we achieved improvements in coating quality and properties by using laser-assisted cold spraying compared to traditional medium-pressure cold spraying [2]. Structure was denser and adhesion was higher together with higher deposition efficiency.…”

Hot Corrosion Resistance of Laser-Sealed Thermal-Sprayed Cermet Coatings

“…Laser technology has become the object of increasing interest as a viable, affordable, and reliable sealing and densification post-treatment process, in thermal spray coatings, for improving the performance of the coatings [26][27][28][29][30][31][32][33][34][35].…”