活塞裙表面等离子喷涂钼涂层的研究

发布时间：2017-12-31 09:00

本文关键词：活塞裙表面等离子喷涂钼涂层的研究　出处：《江苏科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：本文采用等离子喷涂技术在铸铁表面制备了Mo涂层。以涂层结合强度、孔隙率、显微硬度为综合指标,对等离子喷涂工艺参数进行正交试验,得出喷涂Mo涂层的优化工艺参数。然后按优化工艺参数制备Mo涂层,采用SEM、EDS、XRD等分析方法对其显微组织和物相结构进行了研究,并对涂层的结合强度、显微硬度及孔隙率进行了测定;通过热震试验和摩擦磨损试验研究了涂层的热疲劳寿命及其摩擦性能;对Mo涂层进行超声冲击处理,研究了改善涂层综合性能方法的可行性。研究结果表明,在本试验选定的参数范围内:等离子喷涂工艺参数对涂层综合性能影响的主次顺序为:喷涂功率主气流量喷涂距离送粉速率。采用优化工艺参数制备的Mo涂层,结合强度为67.16MPa、涂层孔隙率为5.78%、显微硬度为310HV。等离子喷涂过程中无氧化行为发生,涂层组织均匀致密,结合良好,结合方式为机械锚合。Mo涂层的表面硬度和横截面硬度都存在较大的分散性,且表面硬度比横截面硬度高,显著地服从Weibull分布。Mo涂层热疲劳寿命较好,达到了较高的宏观启裂次数和失效次数;Mo涂层在热震过程中部分形成物相Mo O和Mo O3;热震后涂层的显微硬度增大,但仍存在较大的分散性。干摩擦条件下,铸铁基体的耐磨性能优于涂层。常温下,Mo涂层主要磨损机制是疲劳磨损和氧化磨损;基体的磨损机制主要是粘着磨损和磨粒磨损,兼有氧化磨损。润滑条件下,涂层的摩擦性能有了明显的改善,涂层的摩擦系数随着载荷的增大而增大,随着转速的增大而减小。同等条件下涂层的耐磨性能优于基体。常温下,基体的磨损机制与干摩擦条件下相同,而涂层的磨损机制发生改变,以粘着磨损为主,兼有氧化磨损。采用超声冲击处理技术能够显著的改善Mo涂层的综合性能。涂层表面粗糙度由Ra=35.279um降为2.845um;涂层表面硬度平均提高了35%;近表面层孔隙率降低了41.4%;涂层热疲劳寿命在一定程度上得到了提高。
[Abstract]:This paper adopts the cast iron surface Mo coating was prepared by plasma spraying technology. The bonding strength, porosity, microhardness as comprehensive indexes, orthogonal experiments were carried out on the technological parameters of plasma spraying, the optimum technological parameters of spray coating of Mo. Then according to the optimum process parameters of preparation of Mo coating by SEM, EDS, XRD and other analysis methods the research on the microstructure and phase structure, and the bonding strength of the coating, micro hardness and porosity were determined; the thermal shock test and the friction and wear properties of the coating on the thermal fatigue life and friction performance of Mo coatings; ultrasonic impact treatment, study the feasibility of improving the comprehensive performance of coating method. The results show that in the range of parameters selected in our experiment in order: the influence of plasma spraying parameters on the comprehensive performance of coating for spraying main gas flow from the spraying power From the powder feeding rate. The optimal technological parameters for preparing Mo coating, bonding strength of 67.16MPa coating, the porosity is 5.78%, the microhardness of 310HV. plasma spraying oxidation behavior in the process of combining with the microstructure of the coating is uniform and compact, good surface hardness and hardness of cross section by means of mechanical anchoring of.Mo coatings are dispersed larger than the cross section and the surface hardness, high hardness, obviously obeys the Weibull distribution of.Mo coating on thermal fatigue life better, to achieve a higher number of macro crack initiation and failure number; Mo coating on the thermal shock in the process of forming part of the phase Mo O and Mo O3; the microhardness of coating is increased after thermal shock, but still there is a large dispersion. The dry friction condition, wear resistance of cast iron matrix is better than that of Mo coating coating. Under normal temperature, the main wear mechanism is fatigue wear and oxidation wear; wear mechanism of matrix if adhesive wear And abrasive wear, oxidation wear. Both the lubrication condition, the friction properties of the coatings was improved obviously, the friction coefficient of the coating increases with the increase of the load, and decreases with the increase of speed. The wear performance is better than that of coating under the same condition. Under normal temperature, the wear mechanism of the matrix and dry friction conditions of the same change, and wear mechanism of the coating, adhesive wear, oxidation wear. The comprehensive performance of both the ultrasonic peening treatment technology can improve Mo coating significantly. The surface roughness is reduced from Ra=35.279um to 2.845um; the coating hardness was increased by 35%; near surface layer porosity decreased by 41.4%; the thermal fatigue life of the coating has been improved to a certain extent.

【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG174.4

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