In this work, tungsten carbide coatings are deposited by low-pressure cold spraying in order to assess the influence of powder compressive strength and binder materials on coating properties. Powder compressive strength was measured with a micro-compression tester, and cobalt and FeCr in different proportions were used as the metal binder. It was found that compressive strength affects coating hardness as well as deposition efficiency and that the optimum value for deposition efficiency is about 200 MPa. The results also indicate that dense coatings can be produced with either binder material, although coatings with an FeCr binder are the hardest.

Ceramic coating is a very important technique used to develop structures that resist wear, corrosion, or oxidation. In this study, the Powder Jet Deposition (PJD) technique is used to form ceramic coatings on structures. The PJD technique is similar to the cold spray technique, but it can be used to coat ceramic layers under room temperature and atmospheric conditions. Therefore, PJD was used for the creation and on-site repair of ceramic coatings on large, complicated structures. The aim of this study is to optimize the spray conditions for an aluminum titanate (TiAl 2 O 5 ) coating on various substrates using the PJD technique and to evaluate the mechanism of ceramic deposition. In the case of the cold spray technique, a high particle velocity is essential to cause the large-scale plastic deformation of particles that is necessary for deposition. However, while using PJD on ceramic oxides, lower particle velocity proved to be a better deposition condition. The optimized spraying pressure, resulting in the thickest coating, was approximately 0.05 MPa. The particle velocity as measured using a high-speed camera was approximately 90m/s. Therefore with PJD, it is optimal to use a low velocity within a narrow range to form a ceramic coating.

In cold spray, feedstock powders are accelerated by supersonic jet with solid phase and deposited onto substrate. Compare with the conventional thermal spray, the coatings have low porosity without oxidation and decomposition. This study examines the effect of the powder compressive strength of each particle on coating deposition characteristics using two types of Ni powders, manufactured in a different process, in cold spray. The result indicated that heat treatment reduced the powder compressive strength, and the decrease of the powder compressive strength was related to the increase of bond strength of particles and deposition efficiency. In addition, it was shown that the powder compressive strength has an influence of deposition mechanism.