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航空发动机高温固体润滑和耐磨涂层材料的研究
Alternative TitleStudy of Turbo-Engine’s Coatings with Solid Lubricating and Wear-Resistant Effects Used at Elevated Temperatures
张文婷
Subtype硕士
Thesis Advisor张伟刚 ; 杜令忠
2013-05-01
Degree Grantor中国科学院研究生院
Degree Discipline材料学
KeywordNicocraly/cr2o3/agvo3涂层   等离子喷涂   力学性能   摩擦磨损   热应力   有限元分
Abstract先进航空发动机的高压压气机和涡轮部位主要采用刷式封严结构,以提高封严效率和减少重量。为了满足航空发动机刷式封严部件苛刻的工况条件要求,通常采用热喷涂技术在转子轴表面制备高温固体润滑和耐磨涂层,以减小转子轴和刷丝之间的摩擦系数,降低两者的磨损量。涂层在使用过程中,因受到循环热应力,涂层结构常因热应力过大而剥落失效。为了制备可以在宽温域使用的高温固体润滑和耐磨涂层材料,本论文设计并采用离心喷雾造粒技术制备了NiCoCrAlY/Cr2O3/Ag、NiCoCrAlY/Cr2O3/AgVO3和NiCoCrAlY/Cr2O3/Ag/AgVO3三种复合粉体,同时制备了NiCoCrAlY/Cr2O3粉体做对比分析;采用等离子喷涂技术制备了四种复合涂层材料,研究了涂层的结构与性能,并采用有限元的方法分析了涂层的热应力研究涂层弹性模量与涂层结构对热应力的影响。研究发现:(1)AgVO3在NiCr合金中表现出良好的润滑性能。随着AgVO3含量的提高,材料的摩擦系数逐渐下降,当AgVO3的含量达到10%以上,摩擦系数的变化不再明显。综合考虑涂层的摩擦磨损性能和显微硬度,当AgVO3的添加量为10%时,材料即可表现较优异的润滑性能。(2)采用喷雾造粒技术成功制备了NiCoCrAlY/Cr2O3、NiCoCrAlY/Cr2O3/Ag、NiCoCrAlY/Cr2O3/AgVO3和NiCoCrAlY/Cr2O3/Ag/AgVO3四种复合粉体,性能可以满足等离子喷涂的要求;采用等离子喷涂技术成功制备了NiCoCrAlY/Cr2O3、NiCoCrAlY/Cr2O3/Ag、NiCoCrAlY/Cr2O3/AgVO3和NiCoCrAlY/Cr2O3/Ag/AgVO3四种复合涂层,发现涂层均具有良好的抗热震性能,结合强度和显微硬度满足使用要求。由于AgVO3与NiCoCrAlY/Cr2O3有良好的润湿性,AgVO3的加入提高了涂层的结合强度。(3)润滑相AgVO3的加入有效降低了涂层的摩擦系数,在整个测量温度范围内,NiCoCrAlY/Cr2O3/AgVO3涂层的摩擦系数维持在0.20~0.55之间; AgVO3相的加入有效降低了对磨件的磨损,对于减小刷丝的磨损、保证封严结构的使役性能有重要意义。机理分析研究发现,AgVO3相熔化后会迅速铺展、附着在NiCoCrAlY/Cr2O3涂层上,所以在涂层不断磨损的过程中,始终保持一定量的AgVO3相存在于磨损表面;AgVO3相熔化后,在摩擦力的作用下完全铺展在磨痕表面,从而起到良好的润滑效果。(4)材料学计算表明涂层的弹性模量、结构不同时,材料内部的热应力分布及失效形式也不同:封严层的弹性模量越高,越容易产生裂纹并与粘结层脱落;封严层或粘结层的厚度越小,其结构内部越容易产生裂纹,二者的厚度越大,其结合界面处越容易脱落;封严层的弹性模量及涂层的结构、厚度,均对粘结层与基体结合处的应力差值影响较小;在热震和结合强度的试验中,多发生封严层的脱落而失效,所以在涂层的设计中应该注重减小封严层与粘结层处的应力差值,结合有限元分析的结果,在已设计的四种涂层中得出最优的涂层结构设计方案为: NiCoCrAlY/Cr2O3/Ag/AgVO3,粘结层0.1mm, 涂层0.2mm。
Other AbstractBrush seal system will be used on the high-pressure compressor and turbine blades in advanced turbo-engines. The high-temperature solid lubricating and wear-resistant coating must be prepared on the turbo-engine by thermal spraying technology to reduce the wear rates of the rotor shaft and brushes and satisfy the harsh service environment need for the brush seal parts. A major form of failure of seal coatings is peeling-off effects caused by the too high thermal stress in the materials. In this study, the NiCoCrAlY/Cr2O3/Ag, NiCoCrAlY/Cr2O3/AgVO3 and NiCoCrAlY/Cr2O3/Ag/AgVO3 composite powders were designed and prepared by spray granulation technologies, while NiCoCrAlY/Cr2O3 composite powders were prepared as a contrast sample. Then the composite coatings were prepared by atmospheric plasma spray (APS) and the microstructure and properties of the coatings were systematically investigated. The thermal stress of the coatings was studied by a finite element analysis method. Some main conclusions are summarized as follows: (1) AgVO3 powder performed well lubricating behaviors in NiCr alloy. The friction coefficient (FC) of NiCr/AgVO3 decreased with the amount of AgVO3 increasing and changed a little when the amount of AgVO3 was greater than 10%. The micro hardness would decrease with the amount of lubrication phase increasing. From above all, it can be seen that AgVO3 can perform a best lubricating behavior when the addition amount of it is 10%.(2) NiCoCrAlY/Cr2O3、NiCoCrAlY/Cr2O3/Ag、NiCoCrAlY/Cr2O3/AgVO3 and NiCoCrAlY/Cr2O3/Ag/AgVO3 composite powders were prepared by atmospheric plasma-spray method, with NiCoCrAlY/Cr2O3 powders as a contrast sample. All the four composite powders can meet the plasma spraying requirement. NiCoCrAlY/Cr2O3、NiCoCrAlY/Cr2O3/Ag、NiCoCrAlY/Cr2O3/AgVO3 and NiCoCrAlY/Cr2O3/Ag/AgVO3 composite coatings were prepared by atmospheric plasma spraying method. As AgVO3 can completely attach to the metal phase after melt and enhance the binding force in the coatings, the bonding strength of NiCoCrAlY/Cr2O3/AgVO3 is higher than that of NiCoCrAlY/Cr2O3. (3) NiCoCrAlY/Cr2O3/AgVO3 performed a good lubricating behavior at the whole test temperature, with its FC maintained between 0.20 and 0.55. AgVO3 phase effectively reduced the FC of NiCoCrAlY/Cr2O3 coating at the whole range of test temperature. The result of wetting experiment showed that after melting, AgVO3 spread out quickly on the surface of NiCoCrAlY/Cr2O3 composite coating. So during the process of rubbing, there would always be a certain amount of AgVO3 existed on the worn surface. After melting completely, AgVO3 would spread out and form a lubricating film on the worn surface under the shearing force. Meanwhile, the wear rate of Si3N4 balls decreased a lot when rubbing with NiCoCrAlY/Cr2O3/AgVO3 composite coatings. So the addition of AgVO3 can effectively reduced the wear rate of wear part, which is important for reducing the abrasion of brushes during the start-up process and ensuring the performance of the seal structure.(4)The thermal stress distribution and failure mode of coatings would vary with the different elastic modulus and coating structures: The seal layer is prone to crack and peel off from adhesive layer with the elastic modulus increasing; the seal layer and adhesive layer are prone to crack with the thickness increasing; both the elastic modulus and the structure of coatings almost have no affect on the stress difference between adhesive layer and matrix. The result of thermal shock and bonding strength test showed that the cracks and peel off mainly happened in the seal layers. So according to the results of finite element analysis, the optimized design of the four designed composite coatings is NiCoCrAlY/Cr2O3/Ag/AgVO3,with the seal layer is 0.2 mm and the adhesive layer is 0.1 mm.
Pages75
Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/8264
Collection研究所(批量导入)
Recommended Citation
GB/T 7714
张文婷. 航空发动机高温固体润滑和耐磨涂层材料的研究[D]. 中国科学院研究生院,2013.
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