Analysis of YSZ-Al2O3/YSZ Flame Sprayed Thermal Barrier Coating to Thermal Resistance

Abstract

TBC (Thermal Barrier Coating) with YSZ-Al2O3/YSZ as top coat (TC) and MCrAlY alloy as bond coat (BC) marked as YSZ-Al2O3/YSZ double layer TBC was used for thermal barrier material on rocket nozzle wall. Several test have been conducted (thermal test and SEM-EDX). Thermal test was divided into two part, Thermal Torch and Non-isothermal Oxidation Test which is used for measure the resistance of TBC structure against oxyacethylene flame penetration as a miniature of thermal static test for rocket nozzle until the specimen was failure and used to measure the resistance against non-isothermal oxidation as well as investigate the growth of TGO (Thermally Grown Oxide) layer on interface between TC/BC for thermal torch and non-isothermal oxidation test respectively. This test was performed at 1100o C with 10°C/min heating rate. The results showed that the improvement of feed rate on topcoat powder gave the effect on the surface morphology of topcoat. Lower feed rate bring in a coarse surface morphology and tend to be porous. Al2O3/YSZ composite layer affect on the growth of TGO layer after thermal test, which indicates the lower growth of TGO especially for 15%Al2O3/8YSZ. TGA test showed that the sample began to oxidize at temperature range c.a 1000 – 1030°C, however 1st derivative analysis indicated that 15% Al2O3/8YSZ, 14 g/min was the most stable sampel. Moreover this material has a good resistance from torch destruction.