Porous body, honeycomb filter, microstructure analysis method, program for same, and microstructure analyzer

A ceramic honeycomb filter comprising a porous body including a porous base material having a major surface and a porous surface layer formed on the major surface of the base material,

• wherein the porous body has a porosity P [%] in the range of 25%<P<70% and a thickness T in the range of from 100 μm or more to 600 μm or less and the surface layer has a thickness Ts>0 μm,
• wherein the surface layer thickness Ts and the porosity P of the porous body satisfy a following formula (1):
• P≥0.54 Ts (1)
• wherein, the surface layer thickness Ts is determined by collecting porous-body data in which positional information providing a position of a voxel is associated with voxel type information including information that allows determination as to whether the voxel is a spatial voxel representing a space or an object voxel representing an object is prepared through three-dimensional scanning of a region including a surface of the porous body, and then performing the following steps using the porous-body data;
• (a) a step of defining an imaginary surface that is in contact with at least one object voxel present in the surface of the porous body,
• (b) a step of identifying, as surface layer straight-pore voxels, spatial voxels in contact with the imaginary surface and spatial voxels that continuously lie from the imaginary surface toward an inside of the porous body in a thickness direction, which is perpendicular to the imaginary surface and which extends toward the inside of the porous body, and
• (c) a step of successively shifting the imaginary surface in the thickness direction to define the imaginary surface after each shift as an imaginary reference surface, identifying, as a surface-layer region start plane, an imaginary reference plane in which a straight-pore opening ratio denoting a proportion of the surface layer straight-pore voxels occupying the imaginary reference surface becomes 98% or below for first time, identifying, as a surface-layer region end plane, an imaginary reference plane in which the straight-pore opening ratio becomes 1% or below for first time, and deriving, as a surface layer thickness Ts, a distance between the surface-layer region start plane and the surface-layer region end plane in the thickness direction.