By using GCF type high-pressure cauldron to simulate the water-steam environment higher than 350 ℃

the film-forming test of three kinds of metals commonly used in water-steam systems of thermal power units

namely 20G

T22

and SA210A-1

has been carried out by using pure octadecylamine under water-steam environment of temperature higher than 350 ℃

and the effectiveness of film-forming being evaluated by using methods of copper sulfate spot out test

ac resistance

and the polarization curve.The regression analysis of film-forming results has been carried out using software MATLAB 6.5.Results show that the very good film can form on surface of three said metallic materials under temperature 470~490 ℃

and the concentration of octadecy lamine being 60~70 mg/L

the time of constant temperature being 3~5 h

and the pH value being about 8.8

among these factors

the influence of pH value upon film-forming effectiveness is the largest

the optimal pH value is 9.0.The film-forming effectiveness of octadecylamine on surface of different metallic materials boasts difference.