A series of tests have been carried out to evaluate the protective properties of 'Permagraphed' surfaces as distinct from their lubricant value.

 The corrosive media chosen were:

·        Hydrochloric acid

·        Sulphuric acid

·        Phosphoric acid

·        Sodium Hydroxide (Caustic Soda)

 Mild steel test bars were 'permagraphed' and suspended in baths containing 5% by volume of each corrosive agent and maintained at a temperature of 80°C for a period of 30 minutes.

At the end of the term the test pieces were withdrawn for visual examination, wiped dry, and polished vigorously with white cotton cloth to asses the adhesion of the dry lubricant coating.

 The results were as follows:

·   Hydrochloric acid - no visible change, no discoloration of cloth 

·   Phosphoric acid      -   as above                                                     

·   Sulphuric acid - Slight visible change, slight discoloration of cloth

 Further test pieces were prepared by permagraphing and then passed through the silicone coating before being subjected to the same tests, with the following results:

 ·    Hydrochloric acid - no visible change, no discoloration of cloth

·     Phosphoric acid   -   as above                    

·    Sodium Hydroxide -  as above                      

·    Sulphuric acid        -  as above                           

 It was noted that on removal from the baths the 'siliconed' test pieces shed moisture immediately, and it seems reasonable to conclude that this will lead to much longer periods of protection from corrosion, since the corrosive agents will remain in contact with the components for a shorter time.

Introduction I Background I Applications