大气等离子喷涂SrZrO_3热障涂层工艺与性能的研究
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摘要
目的探究大气等离子喷涂制备Sr ZrO_3涂层的融化状态最好、沉积效率最高的最优工艺,研究SrZrO_3热障涂层的热物理性能及其热循环寿命。方法采用大气等离子喷涂技术制备SrZrO_3热障涂层,通过设计田口实验研究不同的喷涂工艺对粉末融化状况和沉积效率的影响,采用扫描电镜观察涂层融化状况等。采用优化后的工艺制备厚涂层,使用高温热膨胀仪和激光导热仪测试涂层的热膨胀系数、抗烧结性能以及热扩散系数。结果当喷涂距离为90 mm时,SrZrO_3涂层沉积效率最高,最大单遍喷涂厚度达到15.3μm;当喷涂距离为100 mm时,涂层的熔化状态最好。制备态SrZrO_3涂层中出现第二相t-Zr O_2,1600℃热处理条件下,随着热处理时间的延长,t-Zr O_2逐渐消失,热处理360 h后,m-ZrO_2的质量分数逐渐增加至27%。SrZrO_3涂层热膨胀系数为(8～10)×10~(-6) K~(-1)(200～1400℃),随着热处理时间的延长,涂层的热膨胀系数逐渐降低。SrZrO_3涂层的热导率随着热处理时间的延长先增加后减小,热处理360h后SrZrO_3涂层的热导率为1.82W/(m·K)(1000℃)。SrZrO_3/YSZ双层涂层炉内循环548次后,涂层整体脱落。结论 SrZrO_3涂层最优喷涂工艺为电流550 A、氩气流量40 L/min、氢气流量10 L/min、喷涂距离100 mm、功率35.8 kW。随着热处理时间的延长,涂层中的第二相m-ZrO_2能够降低涂层的热膨胀系数和热导率。SrZrO_3/YSZ双层涂层的循环次数远高于SrZrO_3单层涂层。
Objective To explore the optimum spray parameters of the SrZrO_3 coating prepared by atmospheric plasma spray to obtain the better melted coating with higher deposition efficiency and research the thermophysical properties and thermal cycling behavior of the SrZrO_3 coatings. Methods The SrZrO_3 thermal barrier coatings were prepared by atmospheric plasma spray(APS). Taguchi design of experiments(DOE) was employed to investigate the effect of different spray parameters on powder melting and coating deposition efficiency; and a scanning electron microscopy(SEM) was used to analyze the melting status of the SrZrO_3 coating. Thick coating was prepared with the optimized spray parameters. And the thermal expansion coefficients, sintering shrinkage kinetics and thermal diffusivities of the SrZrO_3 coating were measured with high-temperature dilatometer and laser flash method, respectively. Results The highest deposition efficiency of the SrZrO_3 coating was obtained at a spray distance of 90 mm, with a maximum single-pass coating thickness of 15.3 μm; while the coating melted more completely at a spray distance of 100 mm. The content of the secondary phase t-ZrO_2 developed in the as-sprayed SrZrO_3 decreased and disappeared gradually upon heat-treatment at 1600 ℃; while the content of m-ZrO_2 gradually increased to 27 wt.% after heat-treatment at 1600 ℃ for 360 h. The thermal expansion coefficients of the SrZrO_3 coating was 8-10×10~(-6) K~(-1)(200 ℃-1400 ℃), that decreased gradually upon heat-treatment. The thermal conductivity of the SrZrO_3 coating increased first and then decreased with the prolonged heat-treatment time, that was 1.82 W·m~(-1)·K~(-1)(1000 ℃) after heat-treatment for 360 h. The furnace cycling lifetime of the SrZrO_3/YSZ double ceramic layer coating was 548 cycles with the fully spallation of the coating. Conclusion The optimum spray parameters of the SrZrO_3 coating are as follows: arc current 550 A, argon flow rate 40 L/min, hydrogen flow rate 10 L/min, spray distance 100 mm, power 35.8 kW. The thermal expansion coefficient and thermal conductivity of the SrZrO_3 coating decrease with an increase of the secondary phase m-ZrO_2 with the prolonged heat-treatment time. The thermal cycling lifetime of the SrZrO_3/YSZ double ceramic layer coating is much longer than that of the SrZrO_3 single ceramic layer coating.
Objective To explore the optimum spray parameters of the SrZrO_3 coating prepared by atmospheric plasma spray to obtain the better melted coating with higher deposition efficiency and research the thermophysical properties and thermal cycling behavior of the SrZrO_3 coatings. Methods The SrZrO_3 thermal barrier coatings were prepared by atmospheric plasma spray(APS). Taguchi design of experiments(DOE) was employed to investigate the effect of different spray parameters on powder melting and coating deposition efficiency; and a scanning electron microscopy(SEM) was used to analyze the melting status of the SrZrO_3 coating. Thick coating was prepared with the optimized spray parameters. And the thermal expansion coefficients, sintering shrinkage kinetics and thermal diffusivities of the SrZrO_3 coating were measured with high-temperature dilatometer and laser flash method, respectively. Results The highest deposition efficiency of the SrZrO_3 coating was obtained at a spray distance of 90 mm, with a maximum single-pass coating thickness of 15.3 μm; while the coating melted more completely at a spray distance of 100 mm. The content of the secondary phase t-ZrO_2 developed in the as-sprayed SrZrO_3 decreased and disappeared gradually upon heat-treatment at 1600 ℃; while the content of m-ZrO_2 gradually increased to 27 wt.% after heat-treatment at 1600 ℃ for 360 h. The thermal expansion coefficients of the SrZrO_3 coating was 8-10×10~(-6) K~(-1)(200 ℃-1400 ℃), that decreased gradually upon heat-treatment. The thermal conductivity of the SrZrO_3 coating increased first and then decreased with the prolonged heat-treatment time, that was 1.82 W·m~(-1)·K~(-1)(1000 ℃) after heat-treatment for 360 h. The furnace cycling lifetime of the SrZrO_3/YSZ double ceramic layer coating was 548 cycles with the fully spallation of the coating. Conclusion The optimum spray parameters of the SrZrO_3 coating are as follows: arc current 550 A, argon flow rate 40 L/min, hydrogen flow rate 10 L/min, spray distance 100 mm, power 35.8 kW. The thermal expansion coefficient and thermal conductivity of the SrZrO_3 coating decrease with an increase of the secondary phase m-ZrO_2 with the prolonged heat-treatment time. The thermal cycling lifetime of the SrZrO_3/YSZ double ceramic layer coating is much longer than that of the SrZrO_3 single ceramic layer coating.
引文
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[7]马文,宋峰雨,董红英,等.Y2O3与Gd2O3共掺杂Sr ZrO3热障涂层材料的热物理性能[J].无机材料学报,2012(2):209-213.
[8]范金娟,王全胜,马壮.喷涂距离对粒子飞行特征及变形程度的影响[J].材料工程,2003(z1):193-194.
[9]MA W,MACK D,MALZBENDER J,et al.Yb2O3 and Gd2O3 Doped Strontium Zirconate for Thermal Barrier Coatings[J].Journal of the European Ceramic Society,2008,28(16):3071-3081.
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[11]TRAEGER F,AHRENS M,VA?EN R,et al.A Life Time Model for Ceramic Thermal Barrier Coatings[J].Materials Science&Engineering A,2003,358(1-2):255-265.
[12]关振铎,张中太,焦金生.无机材料物理性能[M].北京:清华大学出版社,2011.
[2]RABIEI A,EVANS A G.Failure Mechanisms Associated with the Thermally Grown Oxide in Plasma-sprayed Thermal Barrier Coatings[J].Acta Materialia,2000,48(15):3963-3976.
[3]AND D R C,LEVI C G.Materials Design for the Next Generation Thermal Barrier Coatings[J].Annual Review of Materials Research,2003,33(1):383-417.
[4]NELSON W A,ORENSTEIN R M.TBC Experience in Land-based Gas Turbines[J].Journal of Thermal Spray Technology,1997,6(2):176-180.
[5]MILLER R A,SMIALEK J L,GARLICK R G.Phase Stability in Plasma-sprayed Partially Stabilized Zirconia Yttria[J].American Ceramic Society Bulletion,1983,62(12):1355-1358.
[6]TRICE R W,SU Y J,MAWDSLEY J R,et al.Effect of Heat Treatment on Phase Stability,Microstructure,and Thermal Conductivity of Plasma-sprayed YSZ[J].Journal of Materials science,2002,37(11):2359-2365.
[7]马文,宋峰雨,董红英,等.Y2O3与Gd2O3共掺杂Sr ZrO3热障涂层材料的热物理性能[J].无机材料学报,2012(2):209-213.
[8]范金娟,王全胜,马壮.喷涂距离对粒子飞行特征及变形程度的影响[J].材料工程,2003(z1):193-194.
[9]MA W,MACK D,MALZBENDER J,et al.Yb2O3 and Gd2O3 Doped Strontium Zirconate for Thermal Barrier Coatings[J].Journal of the European Ceramic Society,2008,28(16):3071-3081.
[10]曹学强.热障涂层新材料和新结构[M].北京:科学出版社,2016
[11]TRAEGER F,AHRENS M,VA?EN R,et al.A Life Time Model for Ceramic Thermal Barrier Coatings[J].Materials Science&Engineering A,2003,358(1-2):255-265.
[12]关振铎,张中太,焦金生.无机材料物理性能[M].北京:清华大学出版社,2011.