Pretreatment method for improving antioxidation of steel t91/p91 in high temperature water vapor

A pretreatment method for improving antioxidation of steel T91 /P91 in high temperature water vapor, comprising:

• 1) preparing a slurry:
• adding 0.5-35 wt % of aluminum powder and 65-99.5 wt % of rare earth oxide into a sodium silicate aqueous solution with modulus of 2.4-2.9 and density of 1.1-1.5 g/cm3, and then stirring evenly to prepare the slurry;
• 2) coating the slurry prepared in step 1) on the surface of steel T91/P91;
• 3) drying:
• drying the steel T91/P91 coated in step 2) in an oven at 10-30° C. for 1-4 hours, and then drying at 70-100° C. for 1-4 hours;
• 4) carrying out heat preservation on the steel T91/P91 dried in step 3) in an atmosphere furnace charged with a gas mixture of inert gas and water vapor at the temperature of 600-800° C. for 24-48 hours;
• and then powering off the atmosphere furnace and naturally cooling the steel T91/P91 to room temperature in the furnace;
• 5) cleaning away the powder attached to the surface of the steel T91/P91 to obtain the steel T91/P91 with a surface containing chromium and rare earth oxide.