原位纳米TiC_x颗粒增强铜基复合材料组织与性能研究

发布时间：2018-05-02 19:58

本文选题：燃烧合成 + 铜基复合材料　；参考：《吉林大学》2017年硕士论文

【摘要】：铜及铜合金以其优异的导电导热性、良好的耐腐蚀性和延展性成为工业发展中不可替代的金属材料。然而铜的强度和硬度低,常温和高温耐磨性差,阻碍了铜材料的进一步开发和利用。为满足高速发展的工业对铜及铜合金提出的更高要求,研究者们开发了很多强化铜及铜合金的新方法。其中,向铜基体中添加陶瓷颗粒不仅可以显著提高铜基体的力学性能,还可以减小铜基体导电导热性的降低,使铜基复合材料兼具陶瓷颗粒的高强度和铜基体的良好的导电导热性。目前报道的向铜基体中引入的陶瓷颗粒大部分是微米尺寸,而铝、镁基复合材料的研究结果证明,尺寸较小的陶瓷颗粒对基体的强化效果更加明显,因此,研究纳米尺寸的陶瓷颗粒增强铜基复合材料十分必要。陶瓷颗粒加入到金属基体中的方式分为外加法和原位内生法,与外加法相比,原位内生法不仅可以生成尺寸细小且弥散分布的陶瓷颗粒,还能减少陶瓷颗粒的表面污染,提高增强颗粒与铜基体的界面结合强度,已经成为制备纳米尺寸陶瓷颗粒增强铜基复合材料的首选方法。本文以Cu-Ti-C为反应体系,采用燃烧合成与热压相结合的制备工艺,成功制备出了原位纳米Ti C_x/Cu复合材料。探究了Ti C_x含量和C/Ti摩尔比对Ti C_x/Cu复合材料的增强颗粒尺寸形貌、组织结构、室温压缩性能和导电性能的影响及机制,探究了Ti C_x含量和C/Ti摩尔比对Ti C_x/Cu复合材料室温磨损性能的影响,研究了温度和施加载荷对30vol.%Ti C_x/Cu复合材料高温磨损性能的影响,并讨论了30vol.%Ti C_x/Cu复合材料在高温时的磨损机制。本论文的主要结论有:(1)随着Ti C_x含量的增加,Ti C_x/Cu复合材料中Ti C_x颗粒尺寸增大,复合材料的屈服强度和最大压缩强度先增大后减小,断裂应变先减小后增大,当Ti C_x含量为30vol.%时,复合材料的压缩性能最好,屈服强度为495MPa,最大压缩强度为969MPa,断裂应变为6.88%。弥散分布的纳米Ti C_x颗粒通过Orowan机制,阻碍位错运动从而强化Cu基体,然而,Ti C_x颗粒尺寸的增大减弱了对基体的强化作用,复合材料的压缩性能随之降低。随着陶瓷含量由25vol.%增加至35vol.%,Ti C_x/Cu复合材料的导电率由48%IACS降低至40%IACS。(2)随着C/Ti摩尔比的增加,30vol.%Ti C_x/Cu复合材料中Ti C_x陶瓷颗粒尺寸几乎不变,但陶瓷颗粒的分布由均匀变为少量团聚。复合材料的屈服强度和最大压缩强度减=小,断裂应变增加。这主要是由于C/Ti摩尔比越小,Ti C_x陶瓷的金属性越强,与Cu基体的润湿性提高,在基体中的分布更加均匀,与Cu的界面结合强度更高。而且,剩余的Ti原子固溶在Cu基体内,对材料起到固溶强化的作用。当C/Ti摩尔比为0.4时,30vol.%Ti C_x/Cu复合材料的压缩性能最高,屈服强度为1110MPa,最大压缩强度为1288MPa,断裂应变为4.91%。同时,随着C/Ti摩尔比由0.4增加至1.2,材料的导电率由18%IACS增加至49%IACS。(3)随着纳米Ti C_x含量的增加,Ti C_x/Cu复合材料的室温体积磨损率先减小后增加,当Ti C_x含量为30vol.%时,复合材料的耐磨性最好。Ti C_x/Cu复合材料耐磨性的变化与复合材料硬度的变化规律一致。(4)随着C/Ti摩尔比的增加,30vol.%Ti C_x/Cu复合材料的室温体积磨损率增加。当C/Ti摩尔比0.4时,复合材料的耐磨性最好。虽然复合材料中的Ti C_x陶瓷含量相同,但随着C/Ti摩尔比的增加,固溶在Cu基体中的Ti原子减少,固溶强化效果越来越弱,复合材料的硬度降低,磨粒刺入复合材料表面的深度大大增加,导致磨损性能下降。(5)揭示出纳米Ti C_x颗粒对30vol.%Ti C_x/Cu复合材料高温磨擦磨损性能的影响规律及作用机制。ⅰ)随着温度的增加,纯Cu和30vol.%Ti C_x/Cu复合材料的磨损率先降低后升高,30vol.%Ti C_x/Cu复合材料的磨损率始终低于纯Cu的磨损率。由于Ti C_x陶瓷具有高温稳定性,因此,在高温下依然能够起到弥散强化的效果,使复合材料的高温性能高于纯Cu。180℃时复合材料磨损率最低,主要原因是与常温相比,高温时磨损表面的氧化膜厚度增加,对表面的保护作用增强,降低了复合材料的磨损率。当磨损温度为220℃时,复合材料发生软化,不能支撑表面的MML,形成了大量台阶状剥落层,磨损率增加。ⅱ)揭示出本实验条件下30vol.%Ti C_x/Cu复合材料的高温磨损机制。当温度≤180℃时,复合材料的磨损方式主要为磨粒磨损、轻微的粘着磨损和氧化磨损;当温度达到220℃时,复合材料的磨损机制为剥落磨损、氧化磨损和磨粒磨损。ⅲ)随着载荷的增加30vol.%Ti C_x/Cu复合材料在220℃下的磨损率逐渐增加。220℃时,纯Cu的临界载荷为20N,而30vol.%Ti C_x/Cu复合材料的临界载荷为30N,说明纳米Ti C_x颗粒的加入在高温下也能有效的缓解材料的软化,提高材料的耐磨损性能。
[Abstract]:Copper and copper alloys have become an irreplaceable metal material in industrial development because of their excellent conductivity and conductivity, good corrosion resistance and ductility. However, the low strength and hardness of copper and poor wear resistance at normal temperature and high temperature have hindered the further development and utilization of copper materials. The researchers have developed a lot of new methods to strengthen copper and copper alloys. The addition of ceramic particles to copper matrix can not only significantly improve the mechanical properties of copper matrix, but also reduce the thermal conductivity of copper matrix. The copper matrix composites have both high strength of ceramic particles and good conductive and thermal conductivity of copper matrix. Most of the ceramic particles introduced in the copper matrix previously reported in the copper matrix are micron sizes, and the results of aluminum and magnesium matrix composites have proved that the smaller size ceramic particles are more effective for strengthening the matrix. Therefore, it is necessary to study the nano sized ceramic particles to enhance the copper matrix composite material. The method can be divided into addition method and in-situ method. In comparison with the external addition method, the in-situ endogenous method can not only produce ceramic particles with small size and dispersed distribution, but also reduce the surface pollution of ceramic particles and enhance the interfacial bonding strength of the reinforced particles and the copper matrix. It has become the preparation of nano sized ceramic particle reinforced copper matrix composites. The first choice method. In this paper, in this paper, the in-situ nano Ti C_x/Cu composite was successfully prepared by using Cu-Ti-C as the reaction system. The in-situ nano Ti C_x/Cu composite was prepared. The influence of the content of C_x and the molar ratio of C/Ti on the particle size and morphology of the Ti C_x/Cu composite, the microstructure, the room temperature compression properties and the electrical conductivity were investigated. The effect of Ti C_x content and C/Ti molar ratio on the wear properties of Ti C_x/Cu composites at room temperature was investigated. The effects of temperature and loading charge on the high temperature wear properties of 30vol.%Ti C_x/Cu composites were studied. The wear mechanism of 30vol.%Ti C_x/Cu composite materials at high temperature was discussed. The main conclusions of this paper are as follows: (1) along with Ti C_x content The size of Ti C_x particles in Ti C_x/Cu composites increases, the yield strength and maximum compressive strength of the composite increase first and then decrease, and the fracture strain decreases first and then increases. When the content of Ti C_x is 30vol.%, the compressive properties of the composites are the best, the yield strength is 495MPa, the maximum compressive strength is 969MPa, and the fracture strain is 6.88%. dispersion. The distributed nano Ti C_x particles obstruct the dislocation motion and strengthen the Cu matrix through the Orowan mechanism. However, the increase of the Ti C_x particle size decreases the strengthening effect on the matrix, and the compression performance of the composite decreases. As the content of the ceramics increases from 25vol.% to 35vol.%, the conductivity of the Ti C_x/ Cu composite is reduced from 48%IACS to 35vol.%. 2) with the increase of C/Ti molar ratio, the size of Ti C_x ceramic particles in the 30vol.%Ti C_x/Cu composite is almost constant, but the distribution of ceramic particles varies from uniform to a small amount of agglomeration. The yield strength and the maximum compressive strength of the composites are smaller, and the fracture strain increases. This is mainly due to the smaller the C/ Ti molar ratio, the stronger the metallicity of the Ti C_x ceramics, and the C of the C. The wettability of u matrix is increased, the distribution in the matrix is more uniform, and the bonding strength is higher with the interface of Cu. Moreover, the remaining Ti atoms are solid solution in the Cu base, which can strengthen the solid solution. When the molar ratio of C/Ti is 0.4, the compressive properties of the 30vol.%Ti C_x/Cu composites are the highest, the yield strength is 1110MPa, and the maximum compressive strength is 1288. MPa, the fracture strain is 4.91%., and with the increase of C/Ti molar ratio from 0.4 to 1.2, the conductivity of the material increases from 18%IACS to 49%IACS. (3). With the increase of Ti C_x content, the room temperature volume wear of Ti C_x/Cu composites decreases first and then increases. When Ti C_x is the 30vol.%, the wear resistance of the composites is the best. The change of wear resistance is the same as that of composite material. (4) the wear resistance of 30vol.%Ti C_x/Cu composites increases with the increase of C/Ti molar ratio. When C/Ti molar ratio is 0.4, the wear resistance of the composites is the best. Although the Ti C_x ceramics in the composites contain the same content, with the increase of the C/Ti molar ratio, the solid solution is in Cu The reduction of Ti atoms in the matrix, the strengthening effect of solid solution is getting weaker, the hardness of the composite is reduced, the depth of the abrasive particles is added to the surface of the composite material is greatly increased and the wear property is reduced. (5) the effect of nano Ti C_x particles on the high temperature friction and wear properties of 30vol.%Ti C_x/Cu composites and its mechanism are revealed. The wear rate of pure Cu and 30vol.%Ti C_x/Cu composites increases first and the wear rate of 30vol.%Ti C_x/Cu composites is always lower than that of pure Cu. As Ti C_x ceramics have high temperature stability, the effect of dispersion strengthening can still be achieved at high temperature, and the high temperature properties of the composites are higher than that of pure Cu.180. The wear rate of the composite is the lowest, the main reason is that compared with the normal temperature, the oxide film thickness of the worn surface increases, the protective effect on the surface is enhanced and the wear rate of the composite is reduced. When the wear temperature is 220 C, the composite material softens, can not support the surface of MML, forms a large number of step like peeling layer, and the wear rate increases.) The high temperature wear mechanism of 30vol.%Ti C_x/Cu composites under the present experimental conditions is revealed. When the temperature is less than 180 C, the wear mode of the composites is mainly abrasive wear, slight adhesive wear and oxidation wear. When the temperature reaches 220, the wear mechanism of the composites is peeling wear, oxidation wear and abrasive wear. III) along with the load When the wear rate of 30vol.%Ti C_x/Cu composites increases at 220 degrees C, the critical load of pure Cu is 20N, and the critical load of 30vol.%Ti C_x/Cu composite is 30N. It shows that the addition of nano Ti C_x particles can effectively alleviate the softening of the material and improve the wear resistance of the material at high temperature.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB333

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