Environmental barrier for a refractory substrate containing silicon

A method of providing a substrate in which at least a portion adjacent to a surface is made of a refractory material containing silicon, with protection while the substrate is in use at high temperature in an oxidizing medium, by forming an environmental barrier on the surface of the substrate, the barrier having at least a self-healing layer containing a rare earth silicate, wherein the self-healing layer is formed:

• for at least 90 mol %, by a system constituted by 30 mol % to at most 80 mol % of at least one rare earth silicate RE2Si2O7, RE being a rare earth, and at least 20 mol % to 70 mol % of manganese oxide MnO;
• and
• for at most 10 mol %, by one or more oxides other than MnO, having a eutectic point with SiO2 less than or equal to 1595° C.;
• so as to obtain a self-healing layer presenting a liquid phase having a self-healing function at least throughout the temperature range 1200° C. to 1400° C., while conserving a majority solid phase.