Subsurface damage minimization of KDP crystals

In nanocutting and nanopolishing of potassium dihydrogen phosphate (KDP) crystals, microscopic abrasive particles scratch the material surfaces and cause subsurface damage. This paper aims to establish scratching maps for subsurface damage minimization in KDP crystals by revealing the deformation and material removal mechanisms of KDP crystals based on large-scale molecular dynamics analyses. It was found that both the indenter size and scratching depth have significant influences on the surface integrity of a machined KDP component. The material can experience no-wear, adhering, ploughing and cutting deformation stages under different scratching conditions, and the variation range of the coefficient of friction reflects the stages of the deformation regimes. Scratching maps were also established as guidelines to quantitatively define the “depth/radius — removal regimes” in different lattice surfaces of KDP, which is particularly helpful for the industry in selecting surfacing conditions for high surface integrity.