High Temperature Chloride Corrosion Resistant NiCrTiAlSi/La2O3 Coating at Flue Gas Side of Waste Incineration Power Generating Boiler and Preparation Method Thereof

Abstract

Provided are a high temperature and chloride corrosion resistant NiCrTiAlSi/La2O3 coating at a flue gas side of a waste incineration power generating boiler and a preparation method thereof. The method comprises the following steps: (1) preparing a composite powder; (2) uniformly grinding the composite powder to obtain a spherical composite powder, then drying the spherical composite powder; (3) cleaning and roughening a surface of a substrate; (4) using a thermal spraying technique to spray a primer layer on a heating surface; (5) using a thermal spraying technique to spray the spherical composite powder onto the primer layer; and (6) cooling. The coating obtained by the method comprises a composite coating spray-coated on a surface of the primer layer. A rare element in the form of La 2 O 3 is added to the coating to purify a grain boundary of the coating. The method strengthens the grain boundary and promotes the formation of an oxide film to alter the morphology of the coating, refine a crystal grain, and improve a high temperature and corrosion resistance and oxidation resistance of the coating.

1 . A method for preparing a high temperature chloride corrosion resistant NiCrTiAlSi/La 2 O 3  coating at a flue gas side of a waste incineration power generating boiler, comprising the following steps:
 (1) uniformly mixing Inconel625 alloy powder and NiCrTiAlSi/La 2 O 3  alloy powder in proportion of (85%-90%):(10%-15%) in mass percentage to obtain composite powder, wherein the NiCrTiAlSi/La 2 O 3  alloy powder is composed of following components in mass percentage: 80-85% of Ni, 5-8% of Cr, 3-8% of Ti, 3-8% of Al, 1-3% of Si and 2-4% of La 2 O;   ( 2 ) grinding evenly the composite powder obtained in the step (1) to obtain spherical composite powder and drying the spherical composite powder;   (3) cleaning and roughening a surface of a heating surface of a waste incinerator;   (4) adopting a thermal spraying technique to spray a primer layer on the surface of the heating surface, wherein the primer layer is a NiAl alloy layer;   (5) adopting a thermal spraying technique to spray the spherical composite powder obtained in the step (2) on the primer layer in the step (4); and   (6) cooling to obtain a high temperature chloride corrosion resistant coating of the heating surface of the waste incinerator.   
     
     
         2 - 4 . (canceled) 
     
     
         5 . The method of  claim 1 , wherein in the step (4), the primer layer has a spraying thickness of 80-100 μm; and in the step (5), the spherical composite powder has a spraying thickness of 0.3-0.5 mm. 
     
     
         6 . The method of  claim 1 , wherein the spherical composite powder obtained in the step (2) has a particle size of 25-53 μm, and the spherical composite powder is obtained through ball milling the composite powder obtained in the step (1). 
     
     
         7 . The method of  claim 1 , wherein the thermal spraying technique in the step (4) and step (5) is a supersonic flame spraying technique or a supersonic plasma spraying technique. 
     
     
         8 . The method of  claim 7 , wherein the thermal spraying technique in the step (4) and step (5) is a supersonic flame spraying technique, and technical parameters of the supersonic flame spraying technique are as follows: a pressure of fuel gas propane is 0.35-0.45 MPa, a flow of combustion-supporting gas oxygen is 1600-1800 SCFH, a flow of kerosene is 5-7 GPH, a flow of carrier gas is 20-25 SCFH, a powder feed rate is 50-70 g/min, a gun distance is 300-400 mm, and a linear velocity is 400-600 mm/s. 
     
     
         9 . The method of  claim 8 , wherein in the step (4), the primer layer is sprayed for 4 times; and in the step (5), the spherical composite powder is sprayed for 12 times. 
     
     
         10 - 15 . (canceled)