Generalised bonding criteria in cold spraying: Revisiting the influence of in-flight powder temperature

Inter-splat bonding in cold sprayed coatings is always associated with the impact velocity of the in-flight powder, while the effect of in-flight powder temperature upon impact on the bonding state is often unaccounted. In the present study, influence of powder temperature in addition to the impact velocity on the inter-splat bonding was estimated for a wide range of metals. The inter-splat bonding state of the cold sprayed coatings deposited at different process temperatures and velocities was corroborated with the elastic modulus of the coatings. Elastic moduli of the coatings were estimated from the unbonded splat boundaries obtained by finite element (FE) simulation and found to be comparable with the measured elastic moduli of the coatings obtained from nanoindentation measurements. It is proposed that the powder temperature upon impact influences the inter-splat bonding state in the coatings considerably. This paved a way to select the process parameters and relook into the critical velocity of the impacting powders.

Automated summary

The study highlights the significant influence of powder temperature upon impact on the inter-splat bonding state in cold sprayed coatings in addition to the impact velocity. Elastic moduli of the coatings can be used to estimate the inter-splat bonding state.