| CPC C04B 41/52 (2013.01) [C04B 41/009 (2013.01); C04B 41/5024 (2013.01)] | 8 Claims |

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1. A part made of coated composite material comprising:
a substrate made of ceramic matrix composite material;
a tie-coat layer covering the substrate; and
a protective coating that is on the tie-coat layer and that defines at least one environmental barrier, the protective coating comprising at least one rare-earth silicate, which is selected from the group consisting of ytterbium disilicate (Yb2Si2O7), yttrium disilicate (Y2Si2O7) and any combination thereof, and comprising at least:
a first outer region comprising an outer surface of the protective coating opposite to the substrate and having a first working creep, having deformation of less than or equal to 0.07% when a compressive stress of at least 50 MPa is applied for a duration of 10hours at a temperature of between 1050° C. and 1300° C., said first region comprising at least one grain growth inhibitor in a sufficient quantity to obtain this first creep; and
a second, inner, environmental barrier region, comprising at least one interface of the protective coating with the tie-coat layer and having a second working creep, having deformation of at least 0.01% when a compressive stress of at least 50 MPa is applied for a duration of 10 hours at a temperature of between 900° C. and 1000° C.,
wherein the grain growth inhibitor is selected from the group consisting of zirconium oxide (ZrO2), titanium oxide (TiO2) and hafnium oxide (HfO2) and any combination thereof, and
wherein the content by mass of grain growth inhibitor in the first region is between 0.05% and 10%.
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