Impact Deposition Behavior of Al/B₄C Cold-Sprayed Composite Coatings: Understanding the Role of Porosity on Particle Retention

This study explores the role of porosity in the impact deposition of a ceramic-reinforced metal-matrix (i.e., Al/B${}_4$C) composite coating fabricated via cold spraying. The Johnson–Holmquist–Beissel constitutive law and the modified Gurson–Tvergaard–Needleman model were used to describe the high strain-rate behavior of the boron carbide and the aluminum metal matrix during impact deposition, respectively. Within a finite element model framework, the Arbitrary Lagrangian–Eulerian technique is implemented to explore the roles of reinforcement particle size and velocity, and pore size and depth in particle retention by examining the post-impact crater morphology, penetration depth, and localized plastic deformation of the aluminum substrate. Results reveal that some degree of matrix porosity may improve particle retention. In particular, porosity near the surface facilitates particle retention at lower impact velocities, while kinetic energy dominates particle retention at higher deposition velocities. Altogether, these results provide insights into the effect of deposition variables (i.e., particle size, impact velocity, pore size, and pore depth) on particle retention that improves coating quality.