TP20-24: Constructing Non-P Passivation Films for Cooling Applications: Surface Science Perspective

To comply with environmental regulations or to ameliorate an existing calcium phosphate fouling issue, more customers are looking for non-P cooling corrosion control programs. Simply transitioning from a calcium phosphate to a non-P corrosion control program is relatively seamless due to the slow dissolution of the existing calcium phosphate passivation film to the new non-P passivation film. A more difficult transition is when the surface is neat due to a freshly cleaned surface or a re-tubing of a heat exchange bundle. Utilizing surface analysis techniques coupled with traditional corrosion monitoring for cooling applications the necessary means to construct effective passivation films will be discussed while exploring the various options available: (i) use of metal additives such as Al, Zn, Sn, etc.; (ii) non-P polycarboxylic acid derivatives; and (iii) potential new approaches.