Method for forming heat insulating film, and structure of heat insulating film

Abstract

A method for forming a heat insulating film includes: a step of subjecting an aluminum alloy constituting a surface of a base material to an anodic oxidation treatment to form an anodic oxidation coating film having pores formed in the surface thereat a step of coating on the surface of the anodic oxidation coating film a sealing material that includes a silicon-based polymer solution and particles of a heat insulating material that are dispersed in the silicon-based polymer solution and are particles having an average particle diameter that is larger than an average pore diameter of the pores; and a step of drying and baking the sealing material to form a sealing coating film.

1 . A method for forming a heat insulating film, comprising:
 a step of subjecting an aluminum alloy constituting a surface of a base material to an anodic oxidation treatment to form an anodic oxidation coating film having a surface in which pores are formed;   a step of coating on the surface of the anodic oxidation coating film a sealing material that includes a silicon-based polymer solution and particles of a heat insulating material that are dispersed in the silicon-based polymer solution and are particles having a primary particle diameter that is larger than an outer diameter of the pores; and   a step of drying and baking the sealing material to form a sealing coating film.   
     
     
         2 . The method for forming a heat insulating film according to  claim 1 , wherein the particles are particles that have a hollow structure. 
     
     
         3 . The method for forming a heat insulating film according to  claim 1 , wherein the primary particle diameter of the particles is greater than 30 nm. 
     
     
         4 . A structure of a heat insulating film that is formed by a formation method according to  claim 1 , comprising:
 an aluminum alloy constituting a surface of a base material;   an anodic oxidation coating film that is formed on a surface of the aluminum alloy, and that has a surface in which pores are formed; and   a sealing coating film that is formed so as to cover the surface of the anodic oxidation coating film, and that includes particles of a heat insulating material having a primary particle diameter that is larger than an outer diameter of the pores.   
     
     
         5 . The structure of a heat insulating film according to  claim 4 , wherein:
 the particles are particles that have a hollow structure; and   a porosity of the sealing coating film is from 27.3 to 57.7%.