Application of Parameter Selection Maps in Cold Spraying

Abstract

What would be the most appropriate parameters, namely, gas temperature and gas pressure, for cold spraying of a given feedstock material? This question is the focus of the present contribution. Initially, it is shown that main coating characteristics can be described as a unique function of a dimensionless parameter, defined as the ratio of particle velocity to critical velocity. Subsequently, these velocities and the respective ratio are worked out and expressed explicitly in terms of key process and material parameters, such as gas temperature and particle size. In this way, final properties of cold-sprayed deposits are linked directly to primary cold-spray parameters. Moreover, it is shown that the window of deposition, as well as the relationship between final properties of the deposit and the spraying conditions, can be incorporated conveniently into simple 2-D diagrams, showing contours of the velocity ratio, or the desired coating property, on the plane of the primary process parameters. Based on these diagrams, the process parameters related to a given coating property can be identified and selected, without a need to refer to intermediate variables such as particle velocity. The paper includes examples of the application of these maps for cold spraying of copper.

Comment on ‘Adiabatic shear instability is not necessary for adhesion in cold spray’

“…They also showed that if ASI did occur, then it would lead to an abrupt increase of the interfacial strain from 4 to significantly larger values of around 10, and be manifested by more prominent jetting, as compared to the cases without ASI. The occurrence of ASI was later confirmed by other simulation studies [3], including those using an Eulerian approach [5]. As far as we understand, the main point of those earlier studies was to demonstrate that (1) there was a distinct transition from no-ASI to ASI, and that (2) the velocity marking the transition to ASI (550 m/s for copper) compared well with the experimentally evaluated critical velocity for bonding.…”

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

“…In this sub-section, the effect of impact velocity, particle size, pore size (at a fixed depth of 0.4 ), and particle-to-pore-size ratio on the PEEQ value over the contact surface in the substrate will be further explored to quantify their effects on the PEEQ value, an indicator of particle retention [ 19 , 44 , 59 , 72 , 99 ]. Figure 8 shows the time-evolved PEEQ over the Al substrate for different simulations to investigate the effects of impact velocities ( Figure 8 a), particle sizes ( Figure 8 b), pore sizes ( Figure 8 c), and pore-to-particle-size ratios ( Figure 8 d).…”

“…In this study, a three-dimensional (3D) model of a B C particle impacting on an Al substrate is modeled in an Abaqus/Explicit framework to systematically study the cold spray impact deposition process of ceramic/metal composites with a pore. The B C particle is regarded as deformable with elastic-plastic behavior taken into account, and this is in contrast to the previous models where ceramic particles are assumed to be elastic using isotropic elastic models [ 43 , 46 , 59 , 60 ]. Table 1 summarizes the JHB constants for the B C particle, and these constants are extracted from the previous study by Johnson and Holmquist [ 61 ].…”