Effect Of Preparation Technology On The Structure And Performance Of Thermal Barrier Coatings

High velocity oxygen fuel (HVOF) was used to sprayed bond coatings on super alloysubstrates. Atmospheric plasma spraying (APS) was used to sprayed yttria stabilized zirconia(YSZ) ceramic coatings. Combined with X-ray diffraction (XRD), scanning electronmicroscope (SEM) and electron energy spectrum (EDS) characterization methods to analyzethe influence of the preparation process to the microstructure of the coating, and compared thedifferences of surface roughness, porosity, microhardness, residual stress and thermal shockperformance of coatings with different spraying parameters, to research the effect ofpreparation technology on the coating structure and properties of thermal barrier coatings.The experimental results show that at the gun speed of50mm/s, coatings appear verticalcrack, with the improvement of gun speed, the microcrack in coatings increased; With theincrease of feed rate, the not melt particles increased; Holes in the coating increased with thedeposition temperature, and the coating become more and more uneven, but the cavity incombination of interface become less and combination with the more dense.Porosity in the coating decreases with the gun speed, increases with the feeding rate, andincreases with the deposition temperature. The coating micro hardness up to7.48GPa whengun speed of50mm/s, at gun speed of500mm/s and800mm/s are similar around4.8GPa.When the gun speed is500mm/s, surface residual stress is the smallest about37.5MPa, whengun speed is larger or too low, large residual stress relatively. Feed rate and depositiontemperature has little effect on the coating micro hardness and residual stress. The residualstress in coatings increased with the deposition temperature.Coating thermal shock failure in two ways: one is spalling from the edge to the center theother is peeling off at surface. Spraying at100℃, the visible layered peeling in the coatingappeared after80times thermal cycling, the higher of deposition temperature, the earlierlayered peeling appeared. At low gun speed, the failure mode is whole peeling off. Whenresidual stress in coatings is larger or uneven, thermal cycle service life becomes shorter.