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Metal / Corrosion - Surface Corrosion

Type of Surface Change

  • Stainless steels: Mostly a uniform, flat-gray surface attack that quite often leads to consequential damage in the form of corrosive deposits.
  • Non-stainless steel products (e.g. disposable products such as scalpel blades or old instruments not made of stainless steel, typically with damaged or peeled-off chromium surface layers): Usually extreme corrosion below a pale-black surface.
  • Color-anodized surfaces: Partial or complete loss of color intensity, with crater formation in cases of strong attack.
  • Sintered carbide inserts made of cobalt-bonded tungsten carbide (= TC/Co), also at soldering points: Discoloration/stains and material erosion.
  • Naturally anodized surfaces: Whitish-gray corrosion products, with crater formation in cases of strong attack.

Origin & Causes        

  • Chemical and electrochemical influences only in connection with an excessive acid content as far as stainless steel, sintered carbide metal (TC/Co) and soldered connections are concerned.
  • Long-term impact of water/humidity (condensate) in the case of stainless steel.
  • Impact of acids or alkaline agents in the case of anodized surfaces.

Treatment Recommendations        

  • Rust removal through acid-based cleaning in the case of stainless steel if the damage is still superficial, plus mechanical treatment of soldering points (if applicable) by the instrument manufacturer or a qualified repair service provider..
  • If anodized or sintered carbide (TC/Co) surfaces are affected, the damage is irreparable.

Preventive Measures        

  • Observe application recommendations for acid-based cleaning and neutralizers when treating instruments made of stainless steel or sintered carbide (TC/Co) or items incorporating soldered connections.
  • Sort out and discard disposable products or old steel instruments with damaged surfaces and replace them with stainless steel products.
  • Avoid long-term exposure to humidity (condensate).
  • Treat/process instruments with anodized surfaces in a neutral-pH environment.

Risk Assessment        

  • If surface treatment proves ineffective, replace the affected instruments with new ones (otherwise risk of consequential rust formation or film rust).
  • Loss of color-coding function in color-anodized instruments.