Abstract: The purpose of the present invention is to provide a thermoelectric conversion element having a film which not only maintains sufficient adhesion even when exposed to a high temperature but also exhibits excellent oxidation resistance and crack resistance. The problem is solved by a thermoelectric conversion element including a thermoelectric conversion component, in which the thermoelectric conversion component contains magnesium silicide and/or manganese silicide and is covered with a film containing Si and Zr.

Abstract: The purpose of the present invention is to provide a thermoelectric conversion element having a film which not only maintains sufficient adhesion even when exposed to a high temperature but also exhibits excellent oxidation resistance and crack resistance. The problem is solved by a thermoelectric conversion element including a thermoelectric conversion component, in which the thermoelectric conversion component contains magnesium silicide and/or manganese silicide and is covered with a film containing Si and Zr.

Abstract: The purpose of the present invention is to provide a surface treatment agent which is capable of forming, on a metal material, a film that not only comprehensively satisfies various performance such as corrosion resistance and adhesion but also exhibits excellent corrosion resistance and adhesion even when exposed to a high-temperature environment. The Problem is solved by a surface treatment agent for metal materials, which contains: a compound and/or mixture (A) represented by M2O.SiO2, wherein a molar ratio of SiO2/M2O is in a range of 1.8 to 7.0 and M represents an alkali metal; a stabilized zirconium oxide (B); and a component (C) that contains at least one selected from metal oxide particles and clay minerals except for the compound and/or mixture (A) and the stabilized zirconium oxide (B).