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1、摘 要I原位 TiCp/Ti 复合材料的耐蚀性研究摘 要随着颗粒增强钛基复合材料应用领域的日益扩大，人们开始关注其耐蚀性、耐磨性等非常规力学性能的研究。但由于腐蚀过程影响因素众多，加上复合材料本身组织结构的复杂性， 增加了颗粒增强钛基复合材料腐蚀性能研究的难度。 因此， 对原位 TiC颗粒增强钛基复合材料腐蚀行为的研究顺应该种材料的发展要求，极具现实意义，对钛基复合材料作为结构材料使用的设计具有一定的指导意义。本文采用熔铸法原位合成了 TiC 颗粒增强的钛基复合材料，并以其为研究对象，采用 TG-DTA/DSC 热重分析仪和 M283 恒电位仪分别测试了复合材料的高温氧化行为和常温腐蚀行为，分
2、析了温度、气体介质及流速、碳含量和合金元素 Al 对复合材料高温氧化性能的影响以及碳含量和合金元素 Al 对复合材料腐蚀行为的影响；并按照国家标准 GB10124-88金属材料实验室均匀腐蚀全浸泡试验方法对复合材料进行浸泡试验，进一步分析复合材料的常温腐蚀状况。利用 X 射线衍射、扫描电镜和能谱等手段对氧化/腐蚀后的试样表面进行组织形貌观察及氧化/腐蚀产物分析，阐述了复合材料的氧化/腐蚀机理。复合材料的高温氧化研究结果表明：纯钛及复合材料的氧化动力学基本上遵循抛物线规律；随着氧化温度的升高，氧化时间的延长和环境中氧浓度的提高，材料的氧化越严重；纯钛、Ti 基复合材料和 Ti6Al 基复合材料的
3、抗高温氧化性能依次递增，TiC增强相及合金元素 Al 能显著改善材料的耐高温氧化性能，且增强体含量越高，复合材料的抗高温氧化性越好；钛基复合材料的氧化增重是由 O 原子由外向里扩散为氧化控制步骤的，它的氧化机理因 TiC 的加入而与纯钛(均匀氧化)不同，属非均匀氧化；均匀分布在钛基复合材料中的 TiC 增强体的氧化能够促进局部致密氧化膜的形成，提高复合材料表面上整个氧化膜的致密性，增强它的抗氧化性能；纯钛及 Ti 基复合材料表面的氧化膜主要为金红石型的 TiO2相，而 Ti6Al 基复合材料的表面氧化膜为 TiO2和 Al2O3的复合相。复合材料的常温腐蚀研究结果表明：纯钛、Ti 基复合材料和
4、 Ti6Al 基复合材料的耐蚀性依次下降，TiC 颗粒和 Al 元素的添加均使得 Ti 基复合材料的耐蚀性下降，且随着增强体含量的增高，复合材料的耐蚀性下降；Ti 基复合材料腐蚀后表面的钝化膜为 TiO2相，而 Ti6Al 基复合材料表面的钝化膜为 TiO2和 Al2O3复合钝化层，两种材料在水溶液中的腐蚀机制均为点蚀和电偶腐蚀。摘 要II可见，采用熔铸法制备原位生成 TiC 颗粒增强钛基复合材料时，在合理范围内适当提高增强相的含量、添加适量的合金元素等手段可获得具有优良抗高温氧化性能的复合材料，在适当环境中可充分利用该材料的耐高温性；而对钛基复合材料在水溶液中的常温腐蚀可通过施加一些防护措施
5、加以提高它的耐蚀性。关键词：关键词：钛基复合材料；TiC；高温氧化；电化学腐蚀；腐蚀机制ABSTRACTIIICorrosion Resistance Investigation ofthe In Situ TiCp/Ti CompositesABSTRACTWith the extensive increaseing in the application fields of the PTMCS, someunconventional mechanical properties, such as the rust resistance, wear resistance and so on,st
6、art to attract peoples attention. With the addition of micro-structural complexity of thePTMCS, because of the numerous factors which influence the corrosion course, there aregreat difficulties in the research on the corrosion performance of the PTMCS. Therefore, theresearch on the corrosion perform
7、ance of the in-situ PTMCs adapt to the development of thematerials, and has great realistic signification. And in a certain extent, it can instruct thedesign of PTMCS as the using of structural materials.The samples in situ TiC particle-strengthend titanium matrix composites is fabricatedby the soli
8、dification processing. The high temperature oxidation behavior of the compositesis tested by the TG-DTA/DSC which analyzes the influence of temperature, gas medium,carbon content and alloy element Al on the oxidation resistance of the PTMCs and thenormal temperature corrosion behavior of the composi
9、tes is studied by the M283 whichanalyzes the influence of carbon content and alloy element Al on the corrosion resistance ofthe PTMCs; According to the state standard GB10124-88 The Metal Material LaboratoryCorroding Entire Immersion Testing Method , the composites is immersed in the solution toanal
10、yze the corrosion behaviour. Finally the microstructure of the oxidized/corrodedspecimens is investigated by the way of XRD, SEM and EDS, hoping that theoxidation/corrosion mechanism can be concluded.It is shown by the research result of the oxidation behavior that the oxidation kineticscurve of pur
11、e Ti and composites obeys parabolic law; the higher of the oxidationtemperature, the longer of the oxidation time, the higher of the O density, the more seriousoxidation of the materials; Ti matrix composites and Ti6Al matrix composites have moreoxidation resistance than pure Ti, the addition of TiC
12、 and Al can improve the oxidationresistance of the composites and the more content of the TiC particles leads to the better ofthe oxidation performance; the mass gain of the composites is through the O atomABSTRACTIVproliferating from surface to internal as the oxidized control step, the mechanism o
13、f the insitu TiC particle-strengthend titanium matrix composites is different from the pure Tis,belonging to the inhomogeneous oxidation. The oxidation of TiC particulates distributinguniformly on the TMMCs is able to promote the formation of compact oxide film in the parteare, which can improve the
14、 compact of the whole oxide film on the surface of TMMCs,and improve the oxidation resistance of TMMCs. The oxide scales of pure Ti and Ti matrixcomposites are mainly composed of rutile TiO2, while the components of oxide scale ofTi6Al matrix composites are rutile TiO2 and Al2O3.The research result
15、of the ordinary corrosion behavior of the composites is indicatedthat Ti matrix composites and Ti6Al matrix composites have poorer corrosion resistancethan pure Ti; the addition of TiC and Al can decrease the corrosion resistance of the Timatrix composites and the corrosion resistance of composites
16、decreases with the content ofthe additon TiC increasing; The passive film of Ti matrix composites is composed of TiO2,while the passive film of Ti6Al matrix composites are TiO2 and Al2O3; The corrosionmechanisms of the composites in the solution are pit morphology and galvanic corrosion.Therefore, while fabricating the in situ PTMCS by the solidification processing, thecomposites of excellent oxidation resistance could be produced by means of increasing thecontent of reinforced particle
