Many metals protect themselves from corrosion by forming a passivation layer on their outer surface. This protective layer is composed of metal oxide or metal nitride and is very thin. For stainless steels, the layer may be only 1-3 angstroms thick and for metals such as aluminum and titanium, the layer may be up to 50 angstroms thick. (A human hair is 500,000 angstroms thick for comparison). Passivation can occur naturally with exposure to oxygen or can be assisted by various passivation techniques such as electrolytic anodization, plasma treatment or chemical treatment. Due to the limited thickness of the passivation layer, the substrate being passivated must be very clean to begin with to prevent discontinuities in the passivation layer which would then compromise the protective nature of the passivation layer.
Machining, cutting, welding, polishing or otherwise “working” a metal substrate generally introduces contaminants which prevent the formation of a uniform passivation layer. Even particulate in the shop air can contaminate the metal surface and prevent uniform passivation. Magnus Engineered Equipment can supply the proper equipment to clean and passivate the metal substrates.
Laser or plasma cutting stainless steel or other metals can produce a dross which needs to be removed for part functionality and proper passivation. The same is true for stainless steel or other metal discoloration that occurs from welding. Often, aggressive etchants such as hydrofluoric acid and nitric acid are used to remove dross and less aggressive chemistry can be used to remove discoloration. The use of ultrasonics is useful for removing dross and discoloration and the 20 kHz ultrasonics offered by Magnus Engineered Equipment is the most powerful ultrasonics in the cleaning industry.
Contact Magnus Engineered Equipment to see how we can assist with your metal passivation, dross and discoloration removal needs.