Blistering Bubbles

Corrosion blistering, also called blistering or bubbling, is a common manifestation of corrosion in metals.  This process occurs when a metal surface reacts with its environment, leading to the formation of corrosion products.  The corrosion products often occupy more volume than the original metal, causing the formation of blisters or bubbles on the metal surface.

Key Points about Corrosion blistering

• Corrosion Process  - 
  • Chemical Reaction  -  Corrosion is a electrochemical process where metal reacts with its surroundings.  For example, in the case of iron, the reaction is often with oxygen and moisture in the air, forming iron oxide (rust).

• Formation of Corrosion Products  - 
  • Increased Volume  -  The corrosion products, such as oxides or salts, typically have a larger volume than the original metal.  This expansion causes pressure to build up beneath the intact metal surface.

• Blistering/Bubbling  - 
  • Pressure Buildup  -  As the corrosion products accumulate, they create pressure between the metal surface and the corroded layer.
  • Blisters Formation  -  This pressure can lead to the formation of blisters or bubbles on the metal surface.
  • Visible Signs  -  These blisters are often visible and can sometimes lead to the eventual breakdown of the protective metal layer, exposing more metal to the corrosive environment.

• Corrosion Blistering Types
  • Filiform Corrosion  -  This type of corrosion appears as thread-like filaments beneath the paint or coating on metal surfaces.
  • Pitting Corrosion  -  It involves localized corrosion that leads to the formation of small pits on the metal surface.

• Prevention and Control
  • Protective Coatings  -  Applying protective coatings, such as paints or corrosion inhibitors, can help prevent the metal from coming into contact with corrosive agents.
  • Cathodic Protection  -  This technique involves making the metal a cathode to protect it from corrosion.  Sacrificial anodes or impressed current systems can be used for cathodic protection.

Understanding and addressing corrosion blistering is necessary in industries where metals are exposed to harsh environmental conditions.  Regular inspections, maintenance, and the use of corrosion resistant materials or protective coatings are essential for preventing and managing corrosion related issues.