Effect of Powder Type and Composition on Structure and Mechanical Properties of Cu + Al2O3 Coatings Prepared by using Low-Pressure Cold Spray Process

Abstract

Powder type and composition have a very important role in the production of metallic and metallicceramic coatings by using the low-pressure cold spray process. Furthermore, structure and mechanical properties of Cu and Cu + Al 2 O 3 coatings are strongly influenced by powder characteristics of Cu particles. The aim of this study was to evaluate the effect of different particle types of Cu powder and different compositions of added Al 2 O 3 particles on the microstructure, fracture behavior, denseness, and mechanical properties, i.e., hardness and bond strength. Spherical and dendritic Cu particles were tested together with 0, 10, 30, and 50 vol.% Al 2 O 3 additions. Coating denseness and particle deformation level increased with the hard particle addition. Furthermore, hardness and bond strength increased with increasing Al 2 O 3 fractions. In the comparison between different powder types, spherical Cu particles led to the denser and less oxide-contenting coating structure due to the highly deformed particles.

Microstructure and Corrosion Resistance of Aluminium and Copper Composite Coatings Deposited by LPCS Method

“…However as reported by koivuluoto et. al [13] the microporosity is present in coatings deposited of dendritic copper powder and thus spherical copper powder exhibit better results in open-cell potential measurements. Despite the similar volume ratio of alumina in powder, the microstructure image shows that much more alumina is deposited in aluminium coatings, which is in an amount of 30-34% vol., while the in the copper coating it is about 6-8% vol.…”

“…Despite the use of high temperatures of 600 ˚c in the process, the coating did not show oxidation. The presence of alumina, which tamps the metal, provides high density and minimizes the presence of pores [13,16,31].…”

“…The Al 2 O 3 particles cannot deform and after collision are partially fragmented and rebounded. The high initial concentration of ceramics increases the intensity of this phenomenon [13,16].…”

“…A key factor in increasing the corrosion resistance of the coating is to reduce its porosity. By lowering the porosity an increase in the density of the coating is obtained, which can be achieved by adding a ceramic phase to the powder [3,[10][11][12][13][14][15][16][17]. The most preferred properties of the copper composite coating were observed at 50% vol.…”

“…The most preferred properties of the copper composite coating were observed at 50% vol. addition of Al 2 O 3 [13].…”