Do Thicker Coatings Increase Corrosion Resistance?

March 10 2017 Corrosion



Customers use our coatings to solve corrosion issues. We encourage our customers to thoroughly evaluate the recommended coating in the application because the number of unique environments is infinite, so having definitive test data for a specific anti corrosive application is unlikely. We have, however, studied a broad range of common corrosive environments, and our Silcolloy and Dursan coatings provide great protection benefits in many corrosive conditions when applied to the proper substrate.

Despite our tests, which illustrate good performance from our coatings, customers ask the question "The performance looks good but will a thicker coating make my part even more corrosion resistant?"  As is the case with many questions of rust, the answer is complex, but in short, the answer, I'm sorry to say, is “it depends”. A detailed explanation is provided here.

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We have conducted experiments to investigate the impact of coating thickness on anti corrosion performance within our coatings’ current production thickness ranges. The table below compares our two corrosion resistant coatings, Silcolloy® 1000 and Dursan®, at the low end of their thickness output versus the median to high end thickness output, respectively. The test was done by immersing coated coupons in 6M hydrochloric acid under room temperature, for a preset amount of time (ASTM G31 guidelines).


Thickness range (nm)

Corrosion 24 hours (MPY)

Corrosion 168 hours (MPY)

SL1000 (thin)

250 ~ 320



SL1000 (median to high)

750 ~ 1200



Dursan (thin)

300 ~ 350



Dursan (median to high)

650 ~ 900




Do thicker coatings provide a better corrosion resistance to the surrounding environment?  With all things being equal in the coating, it can. It will create a longer diffusion barrier and restrict corrosive compounds from interacting with the substrate causing rust to occur. However, creating a thicker coating has several potential issues including:

  • Stresses induced as the film grows thicker which can lead to film cracking and delamination
  • Creation of potential interfacial failure sites and the possibility of more stresses throughout the coating
  • Particle generation
  • Growth mechanisms that may impose an upper limit on coating thickness
  • Extended deposition time that leads to metallurgical property change.

Need convincing?  Watch our coatings in action!


While overcoming these issues to develop thicker coatings is an option, SilcoTek continues to take the less is more approach and continues to evolve our coatings to a higher quality and more consistent material to further improve the corrosion resistance of critical components and flowpaths.  By applying a thin high quality layer, SilcoTek takes advantage of both improved corrosion resistance and a better performing high durability surface.  

Advantages of the less is more approach:

  • Order of magnitude improvement in corrosion resistance
  • Maintain high dimensional tolerance
  • Assures a leak free seal in critical flowpaths
  • Allows the amorphous silicon to bend or deflect with the steel surface without failure


Learn more about SilcoTek® corrosion resistant coatings.

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