Impact attrition of sodium chloride crystals

Abstract Impact attrition of cubic NaCl particles has been studied. The particles are produced by cleaving melt-grown ingots to about 1 mm in size, and standardised by chemical polishing and annealing. They are accelerated in an air eductor, and are impacted onto a target in the velocity range 15 – 30 ms−1. The low velocity impact causes extensive plastic deformation on the impacting corner and removal of thin platelets from the faces adjacent to it. The process may be treated as indentation fracture: the ensuing 〈110〉 cracks resemble closely those produced by quasi-static indentation fracture and can be interpreted in the same way. Formation of platelets is attributed to sub-surface lateral cracks, which follow a pattern similar to impact damage of large targets.