Temperature Gradient Test

• In general, when a painted steel plate is in contact with water (including seawater) and a temperature gradient exists between the two sides of the plate:

  • High temperature side of paint film
    Because the direction of diffusion of the heat of the temperature and the direction of permeation of water in the paint film are the same, permeation of water in the film is remarkably accelerated, blisters form on the painted steel material at an early timing, and the adhesion strength of the paint film decreases.
  • Low temperature side of paint film
    In this case, the direction of diffusion of the heat of the temperature and the direction of permeation of the water are in opposite directions. Therefore, permeation of water in the paint film is remarkably suppressed. The time to paint film failure is longer than in a corrosion test under a constant temperature, and loss of adhesion strength is suppressed.

• 

Estimation of Adhesion Durability Life of Painted Steel Plates by Temperature Gradient Test

• It is possible to estimate the durability life (useful life) of a painted steel plate by accurately grasping the temperature of the painted steel (paint film side, steel plate side) under the actual environment.

  (Example) Estimation of adhesion life of inside coating of outdoor water storage tank
  Inside Water on painted film side (20℃) / Paint film / Steel / Water on steel side (30℃) Outside

• By performing a temperature gradient test, it is possible to estimate the adhesion durability life of a painted steel plate by an accelerated test in which a more severe temperature differential (steeper temperature gradient) is applied in comparison with that between the actual paint film and steel plate sides.

  (Example)Adhesion durability life of inside coating of water supply piping
  The adhesion life under the actual service temperature is estimated by performing an immersion test under higher temperatures (2-3 temperature conditions) that the actual service temperature, and the expressing the adhesion life obtained thereby in the form of an Arrhenius plot.

  Test Piece Size
  100 × 100mm

  Possible Test Temperature Range
  High temperature tank side 20-90℃ Low temperature tank side 10-90℃

  Test Solutions
  Water, neutral salt water, acid aqueous solutions, alkali aqueous solutions (Test with aqueous solutions of solvents are not possible.)

Temperature Gradient Test of Steel Plate with Vinyl Ester Lining Containing Glass Flakes