Bonding, reactivity, and mechanical properties of the kinetic-sprayed deposition of Al for a thermally activated reactive Cu liner

Pure Al coatings were fabricated on Cu substrates via kinetic spraying to produce a thermally activated reactive Cu liner. The coatings need to endure high-strain rate severe plastic deformation and react with oxygen during penetration or after penetration of the liner. In this study, the Al powder underwent large exothermic reactions with a small particle size and fast heating rate, as determined from the differential scanning calorimetric analysis. Process optimization of the Al deposition was facilitated by defining the "critical velocity" of an Al particle in the kinetic spraying process based on numerical modeling and computations using ABAQUS finite element codes. The simulation results revealed that the critical velocity of an Al particle at room temperature (RT) is 780 m/s and it decreases as the particle temperature increases. Certain process conditions resulted in improved coating properties as the temperature of the particles was affected by the process gas temperature and pressure. The mechanical properties such as the bond strength of the coatings formed under various process conditions were evaluated and compared. The relationships between the resulting properties, processing conditions, and the structures of the coatings are discussed.