Chloride Salt Corrosion Mechanisms and Their Application in Spacecraft Structures

Nowadays, numerous global spacecrafts are launched, transported, or served in marine environment, but corrosive chloride salts can attack their structures. It is considered in this paper that the chloride salt corrosion failure under low loads consists of pitting, pit-to-SCC transformation, SCC, and brittle–ductile fracture. During the pit-to-SCC transformation processes, the relationships among the normal stress on cleavage planes, the applied stress and the crystal orientations are expressed quantitatively on the basis of the crystallographic features. A typical brittle–ductile fracture mode is sequential or simultaneous occurrence of cleavage and shear. The stress intensity factor and the crack length are employed to evaluate the no-omen SCC and HE failure inside the structural solids. The corrosion area and depth, the weight change and the current density are often applied to characterization of general corrosion damage in multi-scale spacecraft structures. Further, the chloride salt corrosion should be protected systematically from three aspects of anti-corrosion materials, service environment, and concentrated stress. Meanwhile, the acidic cleaning processing must be forbidden to be used in the whole spacecraft life.