抄録
Thermal barrier coating (TBC) was deposited on Ni based superalloy specimens, where bond coat was NiCoCrAlY by high velocity oxygen fuel (HVOF) spraying and top coat was 8mass% yittria stabilized zirconia(YSZ) by atmospheric plasma spraying. Edge indent tests of the specimens were carried out at a temperature of 1073K by using indenters with apex angles of 85° or 120° and under different displacement speeds. In addition, the specimens were heated and held at 1273K for long time, and the edge-indent tests of the specimens were performed both at 1273K and room temperature. The results showed that the delamination load Pd and the delamination energy Ed measured at 1073K after short time holding were larger than those measured at room temperature, and were almost the same irrespective of loading speed. The Pd and Ed at 1073K were large when the apex angle of the indenter was large. The Pd and Ed at 1273K increased with increasing holding time and reached a maximum at 1400ks. With further increase in holding time, the Pd and Ed largely decreased. The Pd and Ed at 1273K were smaller than those measured at room temperature, which means that the coating with sufficient delamination energy at room temperature can be delaminated more easily at high temperature. The edge-indent method is effective for quantitative evaluation of delamination energy of coating at high temperature as well as room temperature.
