A reduced
thermal conductivity thermal barrier coating having improved
impact and
erosion resistance for an underlying
metal substrate of articles that operate at, or are exposed to, high temperatures. This
coating comprises an inner layer nearest to the underlying
metal substrate comprising a
ceramic thermal barrier coating material, as well as a protective outer layer adjacent to and overlaying the inner layer and having an exposed surface. The outer layer has a thickness up to about 5 mils (127 microns) sufficient to impart
impact and
erosion resistance to the
thermal barrier coating, and comprises a zirconia-containing
ceramic composition having a c / a ratio of the zirconia lattice in the range of from about 1.011 to about 1.016 and stabilized in the tetragonal phase by a stabilizing amount of a stabilizing
metal oxide selected from the group consisting of yttria, calcia, ceria, scandia, magnesia, india, ytterbia and mixtures thereof. This
coating can be used to provide a thermally protected article having a
metal substrate and optionally a bond coated layer adjacent to and overlaying the
metal substrate. The thermal barrier
coating can be prepared by forming the inner layer comprising the
ceramic thermal barrier coating material, followed by forming on the inner layer the protective outer layer.