The reusable regeneratively cooled thrust engine is a candidate for the orbital maneuvering system (OMS) engine of H-II orbiting plane. The high performance thrust chamber, however, coupled with extended reuse requirements impose difficult cooling requirements particularly at throat region. To meet the cooling and life enhance requirements, the inner wall of the thrust chamber are fabricated with thermal barrier, such as ceramic coating. However, the main drawback to the use of these ceramic coatings are the delamination between the ceramic side and the metal one during repeated thermal heat load. One promising method of improving adhesion of the ceramic coating to the metal wall in the thrust chamber is to apply the functionally graded materials (FGM) composed of ZrO2 and nickel. The FGM chamber consists of different materials components of ZrO2 and Ni with sequential variation of characteristics from one side of ZrO2 to the other side of nickel. In this study, the long firing tests and the durability tests of the regeneratively cooled 1, 200N thrust engine composed of ZrO2/Ni FGM were conducted with nitrogen tetroxide (NTO)/monomethyl hydrazine (MMH) propellant. The film cooling fraction were reduced to 0% to obtain high performance. An optical multichannel analyzer was used to acquire the exhaust plume spectral data in the firing test. A total of 260 firing tests were performed to evaluate the performance of the engine and to obtain thermal data, and also to inspect the damage of the thermal barrier coatings by using the Reprica method.
