Cold Spray is a material deposition process where the effects of substrate roughness on cratering phenomenon are often observed. In order to understand and explain crater formation on cold sprayed coatings, the laser surface texturing technique is used. This innovative process allows to control the substrate surface roughness and to create a controlled topography. In this study, five hole sizes from 20 to 100 μm diameters with an angle of 45° were drilled to obtain different working craters. Subsequent, build up of the coating was investigated. Aluminum powder and nitrogen were used for this study. The main gas temperature and pressure were respectively 500°C and 3MPa. The morphology and the microstructure of aluminum coatings were characterized by optical microscopy and scanning electron microscopy. Surface improperly filled crater affects bond strength. The objective is to determine the effect of surface morphology on craterisation weakening the bond strength. The erosion velocity creates locally a hydrodynamic penetration leading to strong erosion.

To improve the mechanical properties of aluminum coatings, ceramic reinforcement may be added resulting in an aluminum matrix composite. Two processing routes were investigated to manufacture aluminum matrix composite powders for thermal spraying: ball milling and mixing. Three sizes of SiC reinforcement particles were used: 2, 15, and 25 µm. For the ball-milled powders, morphology and microstructure were investigated as a function of SiC grain size and milling time. It is shown that the hardness of the composite and the efficiency of the spray process depend on the size of the hard particles as well as the preparation method. Friction tests were also carried out and the results are shown to correlate with coating microstructure.