稀土掺杂Gd2 O3对YSZ/（Ni，Al）热障涂层组织与性能的影响

目的提高YSZ/(Ni,Al)复合涂层与基体的结合强度和抗高温氧化性。方法采用电泳沉积的方法,在Inconel 600高温合金表面上沉积YSZ/(Ni,Al)复合涂层和掺杂稀土Gd2O3-YSZ/(Ni,Al)(简称G-YSZ/(Al,Ni))复合涂层,后进行真空烧结,然后对制备好的热障复合涂层进行划痕实验和等温循环氧化实验。通过对样品进行等温循环氧化实验,获取不同氧化时间段的复合涂层样品,并采用SEM和XRD对复合涂层组织和形貌进行分析。结果在1100℃等温氧化过程中,未掺杂稀土元素的氧化增重速率为0.0057 mg/mm2,而掺杂钆元素的氧化速率为0.0049 mg/mm2,氧化增重速率比未掺杂稀土YSZ/(Ni,Al)复合涂层的低。G-YSZ/(Ni,Al)热障复合涂层在等温氧化过程中颗粒长大较小、裂纹少、表面更加致密。真空烧结后的YSZ/(Al,Ni)复合涂层和G-YSZ/(Al,Ni)复合涂层与基体的结合强度约为4.0 N,氧化100 h后,掺杂稀土的G-YSZ/(Al,Ni)复合涂层结合强度为3.5 N,未掺杂稀土的YSZ/(Al,Ni)复合涂层与基体的结合强度为2.6 N。G-YSZ/(Ni,Al)热障复合涂层中存在Gd2Zr2O7相和稳定的Ni Al2O4相,Gd2Zr2O7相具有良好的稳定性以及耐高温氧化。结论掺杂稀土氧化钆的G-YSZ/(Al,Ni)涂层的抗高温氧化性能显著提高。在等温氧化过程中,掺杂稀土元素的G-YSZ/(Al,Ni)复合涂层,其颗粒趋向于均匀化,裂纹明显变少,使得涂层更加致密,表面更加平整。等温氧化100 h后,掺杂了稀土氧化钆的G-YSZ/(Al,Ni)复合涂层基体之间具有更好的结合力,抗剥落性和服役寿命较好。

Effect of rare earth doped Gd2O3 on Microstructure and properties of YSZ/(Ni, Al) composite coatings

ABSTRACT:Objective To improve the high-temperature oxidation resistance and adhesion strength of YSZ/( Ni,Al) composite coatings. Methods YSZ/( Ni,Al) composite coatings were deposited on Inconel 600 superalloy without and with rare earth doped Gd2 O3( G-YSZ/( Al,Ni) ) using the electrophoretic deposition ( EPD) technique, followed by vacuum sintering method. Then the thermal barrier composite coatings prepared were tested by the scratching experiment and isothermal cyclic oxidation experiment. By performing isothermal cyclic oxidation experiment, composite coatings samples of different oxidation period were obtained and the microstructure and morphology of the composite coating were analyzed by means of SEM and XRD. Results In the process of isothermal oxidation in air at 1100 ℃, YSZ/( Ni,Al) and G-YSZ/( Al,Ni) composite coating samples had a rate of oxidation weight gain of 0. 0057 mg/mm2 and 0. 0049 mg/mm2 , respectively. The rate of rare earth doped coating samples was lower than that of the YSZ/( Ni,Al) composite coatings without rare earth. During the isothermal oxidation process, G-YSZ/( Al,Ni) compos-ite coatings had less growth of grain, fewer cracks and denser surface. After vacuum sintering for 2 h, the adhesion strength of G-YSZ/(Al,Ni) and YSZ/(Ni,Al) was both about 4. 0 N, while the adhesion strength of G-YSZ/(Al,Ni) and YSZ/(Ni,Al) af-ter isothermal oxidation in air at 1100 ℃ for 100 h was 3. 5 N and 2. 6 N, respectively. There were Gd2 Zr2 O7 and stable NiAl2 O4 phases in G-YSZ/( Ni,Al) composite coatings as revealed by XRD analysis, and the Gd2 Zr2 O7 phase had a good stability and re-sistance to high-temperature oxidation. Conclusion The high-temperature oxidation resistance of YSZ/( Al,Ni) composite coatings was significantly improved by doping of the rare earth Gd2 O3 . In the process of isothermal oxidation, the particles of the G-YSZ/( Al,Ni) composite coating doped with rare earth tended to be homogenized and the amount of cracks was obviously reduced, mak-ing the surface of coating denser and smoother. After isothermal oxidation in air at 1100 ℃, the G-YSZ/( Al,Ni) composite coat-ing had a better adhesion strength with the substrate, and the spalling resistance and service life were also better.