Soft Particle Impact Temperature Influence on Interfacial Bonding upon Collision with a Hard Substrate Surface

The convoluted relationship between particle size, temperature and velocity in Cold Spray (CS) complicates the process of segregating the effect each of them have on the deposition and adhesion development.

The current study aims to associate the particle impact behavior to its in-flight characteristics by studying and decoupling the influence of particle size and impact temperature and velocity. These effects are investigated for the case of soft particles on hard substrate. By taking advantage of the upstream/downstream powder injection location while using high and low pressure CS systems, it is possible to obtain distinct powder impact temperatures while achieving similar particle impact velocities, allowing a true study of the particle impact temperature inherent effects.

Experimental results reveal an in-situ impingement dependent adhesion at low impact temperature, while at increasing temperatures, the bonding becomes tied to the particle representative factor . The effect of particle impact characteristics are discussed based on particle-particle stacking process, pseudo-plasticity, i.e. fish-scale deformation, adhesion/cohesion and deposition efficiency. A CFD model, using the latest heat transfer correlation developed on novel temperature measurements, is used to evaluate the particle impact temperature. Additionally, the numerically obtained trajectory and complete impact size-dependent characteristics of solely successfully bonded particles are provided.