Thermal barrier layer and process for producing the same

DETAILED DESCRIPTION It is accordingly an object of the invention to provide a product to be exposed to a hot gas and having a base body of metal and bonded thereto a thermal barrier layer, and a process for producing the same, which overcome the disadvantages of the heretofore-known products and processes of this general type.
With the foregoing and other objects in view there is provided, in accordance with the invention, a product to be exposed to a hot gas and having a metallic base body to which a ceramic thermal barrier layer formed with a ternary or pseudoternary oxide, is bonded, in which said oxide has a pyrochlore crystal structure of the structure formula A.
sub.
2 B.
sub.
2 O.
sub.
7.
With the objects of the invention in view, there is also provided a product to be exposed to a hot gas and having a metallic base body to which a ceramic thermal barrier layer formed with a ternary or pseudoternary oxide, is bonded, in which that oxide has a perovskite crystal structure of the structure formula ABO.
sub.
3 in which A is calcium or ytterbium, and when A is calcium, B is hafnium and when A is ytterbium, B is at least one of zirconium and hafnium.
The invention is based on the fact that, until now, materials for thermal barrier layers have predominantly been pseudobinary ceramics, that is ceramic materials having a general structural formula which can be represented as AB.
sub.
2 or A.
sub.
2 B.
sub.
3.
In this case, a material based on zirconium oxide has proved most advantageous.
However, from as little as 900.
degree.
C.
, zirconium oxide displays evidence of aging.
This is caused by the zirconium oxide thermal barrier layer sintering.
As a result, the pores and the voluminous defects in the thermal barrier layer undergo progressive diminishment, and the stresses caused by the different thermal expansion coefficients of the material forming the thermal barrier layer and the material forming the base body are reduced less and less well.
This sintering process is reinforced by material impurities