Corrosion Behavior of 17-4PH Martensite Stainless Steel Sprayed with Sodium Hypochlorite Disinfectant

Abstract

Sodium hypochlorite (NaClO) solution, as an effective and low-cost disinfectant, is widely utilized to achieve disinfection in the industry, but introducing chloride ions causes metal material corrosion. To understand actual corrosion behavior, a comprehensive study of the corrosion behavior of 17-4PH martensitic stainless steels (MSs) by spraying NaClO disinfectant was investigated in this work. The x-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry were used to investigate the element distribution and corresponding valence states of the corrosion product on the surface of the 17-4PH MSs. Hypochlorite ions in the disinfectant decrease the atomic ratio of iron/chromium (Fe/Cr) in the corrosion product layer with the increasing corrosion time, which enhances the corrosion resistance of the studied samples. However, strongly oxidizing hypochlorite ions will promote the formation of trivalent Fe ions (Fe3+), which provokes the initiation and growth of pitting in surfaces where the existence of a Cu-riched domain is due to disinfectant migration.