镍基高温合金上S型薄膜热电偶的制备及性能研究

发布时间：2018-01-01 21:38

  本文关键词：镍基高温合金上S型薄膜热电偶的制备及性能研究　出处：《电子科技大学》2016年硕士论文　论文类型：学位论文

  更多相关文章： S型薄膜热电偶 塞贝克系数 热电性能 镍基高温合金 涡轮叶片

【摘要】：在航空发动机设计验证过程中,热端部件(例如涡轮叶片)的表面温度及温度分布对部件机械强度和使用寿命影响至关重要,如何在发动机工作的恶劣环境中实现对其实时、精确测量成为急需解决的技术难题。相比传统方法的局限性,薄膜热电偶克服了干扰流场、会破坏机械结构等缺点。通过薄膜沉积技术将薄膜热电偶直接制备于被测件表面,与其一体化集成,因此具有结构尺寸小、对测试环境基本无影响、响应速度快、热容量小等优点,在表面温度测量方面具有明显的优势。由PtRh和Pt材料组成的S型薄膜热电偶测温范围广,热电性能稳定,是目前最具应用前景的测温器件之一。本文在前期工作的基础上,对Pt Rh和Pt薄膜以及S型薄膜热电偶的制备及性能展开深入研究:首先,采用磁控溅射方法在氧化铝陶瓷基片上沉积了PtRh和Pt薄膜,系统研究了基片温度、薄膜厚度、退火处理等对PtRh和Pt薄膜表面形貌、电学性能、晶体结构的影响。结果显示,随着基片温度的升高,PtRh和Pt薄膜结构趋于致密,且在基片温度为400℃时电阻率分别降至3.34×10-5Ω·cm和1.89×10-5Ω·cm。随着薄膜厚度的增加两种薄膜均保持较为稳定的电学性能。经过退火处理的Pt Rh和Pt薄膜致密性进一步提高,且在退火温度高于800℃、退火时间大于60 min条件下电阻率保持为稳定值。PtRh薄膜在大气环境900℃时表面存在一定的铑元素氧化现象,高于1000℃后有所回复。其次,在氧化铝陶瓷基片上制备了S型薄膜热电偶,通过静态标定研究了基片温度、薄膜厚度、退火处理等制备工艺条件对S型薄膜热电偶热电性能的影响。结果显示,基片温度为400℃时S型薄膜热电偶塞贝克系数中的散射系数得到明显下降,对应输出热电势在1000℃时相比室温提高了6.78%。薄膜厚度的增加能够有效改善S型薄膜热电偶输出热电势的稳定性,且塞贝克系数基本保持不变;真空800℃退火处理进一步减小了散射系数,输出热电势在1000℃时相比未退火提高了9.08%。在基片温度为400℃条件,薄膜厚度为1μm,并经过真空800℃退火处理60 min得到的S型薄膜热电偶,在300℃至1000℃范围内平均塞贝克系数达到12.10μV/℃,灵敏度K值整体大于0.9,最大温度梯度时的相对误差为-1.85%。最后,分别在镍基高温合金上和涡轮叶片上制备了S型薄膜热电偶,器件结构由下至上分别为Ni Cr Al Y合金过渡层、热生长Al2O3层、Al2O3绝缘层和功能层。结果显示,在300℃至1000℃范围镍基高温合金上的S型薄膜热电偶输出热电势具有良好的线性度和重复性,由于与基片热交换率的提高略小于陶瓷基底,平均塞贝克系数为10.16μV/℃,灵敏度K值整体稳定于0.84至0.90,最大温度梯度时的相对误差为-0.52%。涡轮叶片表面的S型薄膜热电偶经过静态标定和冷效试验考核,仍能够保持热电偶结构完整,并且表现出较好的器件性能。
[Abstract]:In the process of aeroengine design verification, the influence of surface temperature and temperature distribution of hot end components (such as turbine blades) on the mechanical strength and service life of components is very important. How to realize real-time and accurate measurement of engine in bad environment is a technical problem that needs to be solved. Compared with the limitation of traditional method, thin film thermocouple overcomes the interference flow field. The thin film thermocouple is directly prepared on the surface of the tested part by thin film deposition technology and integrated with it, so it has small structure size and has no effect on the test environment. Because of its high response speed and small thermal capacity, it has obvious advantages in surface temperature measurement. The S-type thin film thermocouple composed of PtRh and Pt has a wide range of temperature measurement and stable thermoelectric performance. Based on the previous work, the preparation and performance of Pt Rh, Pt thin film and S-type thin film thermocouple are studied. PtRh and Pt thin films were deposited on alumina substrates by magnetron sputtering. The surface morphology and electrical properties of PtRh and Pt films were systematically studied by substrate temperature, film thickness and annealing treatment. The results show that the structure of PtRh and Pt films tend to be compact with the increase of substrate temperature. The resistivity decreases to 3.34 脳 10 ~ (-5) 惟 路cm and 1.89 脳 10 ~ (-5) 惟 路cm at 400 鈩，

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