Effect of stand-off distance for cold gas spraying of fine ceramic particles (< 5 μm) under low vacuum and room temperature using nano-particle deposition system (NPDS)

► Stand-off distance (SoD) is an important process parameter in cold gas spraying using nano-particle deposition system. ► The effect of SoD was studied with computational fluid dynamics (CFD) and experiment. ► Al2O3 powders were deposited on sapphire wafer with different SoDs from 1 to 7 mm. ► The impact velocity of particle by CFD was correlated with the experimental result. ► CFD results could explain the effect of SoD to the mechanical properties and deposition shape.