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Hot-Dip Aluminizing

Last updated: May 15, 2020

What Does Hot-Dip Aluminizing Mean?

Hot-dip aluminizing is a process in which aluminum steel undergoes a hot-dip coating with alloys such as aluminum silicon alloy.

This process guarantees that the metallurgical bond that exists between the aluminum coating and sheet of steel is strong enough. This in turn produces a substance with distinct property combinations neither possessed by aluminum or steel individually. Steel that has been aluminized has better protection against corrosion and can protect against temperatures as high as 800°C (1472°F).


Corrosionpedia Explains Hot-Dip Aluminizing

There are two types of hot-dip aluminum, differentiated according to their composition:

  • Hot-dip aluminizing in thin aluminum or silicon alloy layers – A composition of 5-11% of silicon is normally used for better adhesion. It is mainly used for preventing corrosion and providing heat resistance properties. It is particularly used in water heaters, mufflers and fireplaces. Aluminum steel can be heat resistant for as high as 500°C with no evident change in the material. However, the silicon content may cause it to develop dark spots. It is also the type of aluminized steel found in most industrial products.
  • Hot-dip aluminizing made with pure aluminum – It is primarily intended for atmospheres needing corrosion resistance. This type is mostly applied in condensers of housing air conditioning systems, corrugated roofing, grain bins and sidings.

Aluminized steel is mainly composed of aluminum oxide on the top layer and a mixture of metals within which may include steel, silicon and aluminum. This is then finished with a final layer of steel.

Both types possess excellent reflectivity properties. At about 800°C, aluminized steel can reflect as much as 80% of the heat and can sustain its toughness at about 700°C. Despite the fact that stainless steel is tougher than aluminum steel, the latter has an enhanced electrostatic surface, making it more capable of reflecting heat.

Aluminized steel can provide higher structural durability and strength in extremely corrosive environments. It is also more cost effective, making it the material of choice by many manufacturing industries.

Hot-dip aluminizing is typically used in:

  • Furnaces
  • Automotive mufflers
  • Water heaters
  • Barbecue burners
  • Fire places
  • Baking pans

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