Improving inter-particle deformation and bonding by preserving transient in-situ deposition temperatures during cold spray

Abstract

Cold Spray (CS) represents a solid-state coating process with promising applications in localized repairs and additive manufacturing. However, the weak inter-particle bonding limits the deposit properties due to low plastic deformation. In this study, the high temperature of the transient in-situ deposition surface shortly after particle impact is proposed to promote inter-particle deformation and bonding. A new in-situ deposit surface is formed after solid particle deposition, showing transient in-situ temperature due to the heat transfer between this particle and the overlay deposit. An equivalent time method is devised to obtain the transient in-situ deposition temperature by significantly accelerating the computation speed by nearly 1000 times. Meanwhile, based on spatio-temporal independence, the time interval between deposited particles reaches thousands of microseconds, showing that the in-situ deposition surface tends to the low substrate temperature. Reducing the time interval between particle impacts enables new particles to be deposited onto surfaces at elevated in-situ temperatures, thus promoting better inter-particle bonding. The results provide a basis for increasing the in-situ surface transient temperature to improve the deposit quality.