Tribological Properties and Corrosion Resistance of Cold-Sprayed Coatings

Dear Colleagues,

Cold gas dynamic spraying, or simply cold spraying (CS), is a solid-state coating technology that has been gaining more and more popularity since it was patented at the end of last century, not only among people working in the thermal spray industry for coating and repairing purposes, but also as an additive manufacturing process that allows building up bulk metal parts layer by layer.

Despite first being investigated for ideally low melting point and ductile metallic materials, as they have a low yield strength and exhibit significant softening at elevated temperatures, this never avoided spreading the challenge to deposit higher strength materials, even ceramics and cermets.

Primarily based on the plastic deformation of depositing powder particles at high velocity onto the substrate, CS avoids any unwanted phase transformation or oxidation occurring in conventional thermal spraying processes, where the thermal energy input leads to full or partial melting of feedstock. Powder characteristics, geometric variables, and processing parameters can result in different microstructures and, consequently, changes on the mechanical, tribological and corrosion properties of the deposit. In order to improve the quality of the coatings, several studies have been performed using post-deposition treatments, i.e., laser irradiation, to enhance coating adhesion and to reduce interconnected porosity. Additionally, heat treatment has been explored with the aim to release plastic strain and make the microstructure more uniform. These topics are of current relevance and make the industries consider the technology an interesting alternative to other processes, leading to potential investment.

The scope of the present Special Issue focuses on recent studies exploring different aspects that may affect either deposits so that the surface properties of less wear- or corrosion-resistant substrates are improved, or to bulk additively manufactured components produced by means of CS. Wear studies may include sliding friction, abrasion, erosion, cavitation, and fatigue performance. Studies on corrosion may include wet corrosion and high-temperature corrosion/oxidation. The following concepts affecting such properties are revised:

• Single or multiphase materials deposited by means of cold spray;
• Influence of different deposition parameters as well as spraying gun systems. Deposition can be produced either by high-or low-pressure cold spraying;
• Influence of different powder morphologies;
• Analysis of residual stresses and how they can affect the resulting properties;
• Effect of post-deposition treatments;
• Computer modeling, simulation to predict coating properties, performance, durability, and reliability in service environments.

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• cold spray coatings
• corrosion resistance
• wear resistance
• mechanical properties