A treatment process for a gas turbine component comprising a bond coating and a ceramic coating, an oxide-forming treatment composition, and a treated component are disclosed. The ceramic coating is contacted with a treatment composition. The treatment composition includes a carrier and a particulate oxide-forming material suspended within the carrier. The particulate oxide-forming material is one or more of yttria oxide, antimony, or tin oxide. The treatment composition is heated to form an oxide overlay coating on the ceramic coating. The treated component includes a ceramic coating and one or both of a corrosion inhibitor and an oxide formed by an oxide-forming treatment composition having the corrosion inhibitor.