Ceramic coating for foundry core

A process for coating a refractory alloy part, the process comprising:

• coating at least one area of a refractory alloy part by a treatment composition, the treatment composition comprising at least one type of preceramic polymer and a solvent, and
• heat treating the refractory alloy part coated with the treatment composition, the heat treating being configured to at least partially convert the preceramic polymer and form a ceramic coating obtained by conversion, the ceramic coating being configured to protect the refractory alloy from oxidation,
• wherein the treatment composition also comprises active fillers configured to migrate by diffusion to the refractory alloy part during the heat treatment, the active fillers being configured to form an alloy coating on a surface of the refractory alloy part, and the alloy coating being located between the refractory alloy part and the ceramic coating obtained by conversion, and
• the alloy coating being configured to generate a protective oxide layer when subjected to oxidizing conditions.