Performance and damage evaluation of a regeneratively cooled thrust enginecoated with ZrO2/Ni functionally graded materials (Evaluation test resultsof a chamber partially coated with ZrO2/Ni FGM made by the electroforming method)

A combustion chamber partially coated with ZrO2/Ni functionally graded mate rials (FGM) was cyclically tested, using a bipropellant of nitrogen tetroxi de (NTO)/ monomethyl hydrazine (MMH) at a chamber pressure (P-c) of 0.9 MPa , to show the effect of such coatings on the life span of the chamber. This thermal barrier coatings were applied using a process that employed the el ectroforming method. The C* efficiency (eta C*) for the durability tests of the partially ZrO2/Ni FGM-coated chamber was 97% at P-c=0.9 MPa and mixtur e ratio (MR) of NTO/MMH=1.65. At the cylindrical section of the chamber, th e thermal barrier coating subsequent to composed of pure ZrO2 remained part ially intact. However, the inner surface coating of the chamber throat sect ion suffered premature delamination. The typical damage mode observed in a carbon fiber-reinforced carbon matrix (C/C) chamber of a bipropbllant engin e in our previous study was also seen near the injector face. In the cycle durability tests, the damage to the coating was inspected by means of the R eplica method. After a total of 260 firing tests, a profile of the coating damage was obtained by means of a computer-aided micro-analyzer (CMA) syste m.