Heat-insulation film, and heat-insulation-film structure

Abstract

In a heat-insulation film, porous plate fillers are dispersed in a matrix to bond the porous plate fillers. The porous plate filler includes plates having an aspect ratio of 3 or more, a minimum length of 0.1 to 50 μm and a porosity of 20 to 90%. In the heat-insulation film, a volume ratio between the porous plate fillers and the matrix is from 50:50 to 95:5. In the heat-insulation film in which the porous plate fillers are used, a length of a heat transfer path increases and a thermal conductivity can be decreased, as compared with a case where spherical or cubic fillers are used.

The invention claimed is: 
     
       1. A heat-insulation film in which porous plate fillers comprising plates having an aspect ratio of 3 or more, a thickness of 0.1 to 50 μm and a porosity of 20 to 90% are dispersed in a matrix to bond the porous plate fillers, and a volume ratio between the porous plate fillers and the matrix is from 60:40 to 90:10,
 wherein when a line is drawn from a first surface to a second surface on an opposite side to the first surface in a thickness direction in a cross section parallel to the thickness direct, a ratio between a sum of lengths of line segments present on the porous plate fillers and sum of lengths of line segments present on the matrix is from 50:50 to 95:5. 
 
     
     
       2. The heat-insulation film according to  claim 1 , wherein a thermal conductivity of the porous plate filler is 1 W/(m·K) or less. 
     
     
       3. The heat-insulation film according to  claim 1 , wherein a heat capacity of the porous plate filler is from 10 to 3000 kJ/(m 3 ·K). 
     
     
       4. The heat-insulation film according to  claim 1 , wherein the porous plate filler comprises pores of a nanoorder. 
     
     
       5. The heat-insulation film according to  claim 1 , wherein the porous plate filler includes a metal oxide. 
     
     
       6. The heat-insulation film according to  claim 1 , wherein the porous plate filler comprises particles having particle diameters of 1 nm to 10 μm. 
     
     
       7. The heat-insulation film according to  claim 1 , wherein a heat capacity of the film is 1500 kJ/(m 3 ·K) or less. 
     
     
       8. The heat-insulation film according to  claim 1 , wherein a thermal conductivity of the film is 1.5 W/(m·K) or less. 
     
     
       9. A heat-insulation-film structure in which the heat-insulation film according to  claim 1  is formed on a substrate. 
     
     
       10. The heat-insulation-film structure according to  claim 9 , which has, on the surface of the heat-insulation film, a surface dense layer including ceramics and/or glass and having a porosity of 5% or less. 
     
     
       11. The heat-insulation-film structure according to  claim 10 , which comprises a buffer bonding layer having a thickness smaller than the heat-insulation film, between the substrate and the heat-insulation film and/or between the heat-insulation film and the surface dense layer.