二元颗粒增强铝基复合材料的制备技术

发布时间：2018-10-10 07:37

【摘要】：本文采用旋转摩擦挤压工艺(Rotating Friction Extrusion Processing,RFEP)成功制备了体积分数为0.75vol%~5.56vol%的碳纳米管增强铝基复合棒材((MWCNTs/Al))及MWCNTs(Multi-walled Carbon nanotubes)和SiCp(Silicon Carbide Particles)体积配比分别为5:1、4:1、3:1、1:1、1:3的二元颗粒增强铝基复合材料,分析了工艺参数(搅拌头旋转速度n(rpm)、送料速度v(mm/s))、搅拌头形貌、碳纳米管体积分数对MWCNTs/Al宏观形貌及性能的影响,并着重研究MWCNTs和SiCp混合配比变化对复合棒材抗拉强度的影响规律。研究结果表明,采用旋转摩擦挤压技术可以制备出成形较好的MWCNTs/ZL114A复合棒材。随旋转速度n增大,复合棒材抗拉强度及延伸率均先增大后减小。当n=435rpm,v=0.6mm/s时,复合棒材成形较好,中心区组织均匀,抗拉强度及延伸率均优于其他参数,不合适的热输入是复合棒材力学性能下降的主要原因。搅拌针级数越多,复合棒材成形越差。在单级搅拌头作用下,复合棒材强度及中心区硬度均高于另外两者。在顺时针旋转的左旋螺纹搅拌针作用下,塑化金属作向下且向外的螺旋运动。随着搅拌针级数增加,塑化金属由中心向外围迁移的次数随之增加,因此三级搅拌头易造成孔洞缺陷。随着MWCNTs含量的增加,棒材表面裂纹呈加剧趋势,抗拉强度先增加后降低,当MWCNTs体积分数为1.28%时,拉伸强度相对于母材提高了近20%,抗拉强度提高的可能原因是内应力趋于均匀化;当MWCNTs/SiCp=4:1时复合棒材成形较好,抗拉强度为184MPa,相比于母材提高了近7%,增强相的定向排列是复合材料强度提高的主要原因,MWCNTs的过度破碎则导致复合材料强度降低。
[Abstract]:In this paper, the binary particle reinforced aluminum matrix composites with volume fraction of 0.75volr / 5.56vol% carbon nanotube reinforced aluminum composite bar (MWCNTs/Al) and MWCNTs (Multi-walled Carbon nanotubes) / SiCp (Silicon Carbide Particles) volume ratio of 5: 1: 4: 1 / 1: 1: 1: 3, respectively) have been successfully prepared by rotating friction extrusion (Rotating Friction Extrusion Processing,RFEP). The effects of process parameters (rotating speed of agitator n (rpm), feed rate v (morphology of mm/s), mixer head and volume fraction of carbon nanotubes) on the macroscopic morphology and properties of MWCNTs/Al were analyzed. The effect of the mixture ratio of MWCNTs and SiCp on the tensile strength of composite bar was studied. The results show that MWCNTs/ZL114A composite bar with good forming can be prepared by rotating friction extrusion. The tensile strength and elongation of the composite bar increased first and then decreased with the increase of rotation speed n. The results show that the composite bar has better forming, uniform central structure, better tensile strength and elongation than other parameters, and improper heat input is the main reason for the decline of the mechanical properties of the composite bar, when nn 435 rpm / s is 0.6mm / s, the structure of the composite bar is uniform and the tensile strength and elongation of the composite bar are better than those of the other parameters. The more the mixing needle series, the worse the forming of the composite bar. Under the action of single stage agitator, the strength and hardness of the composite bar are higher than those of the other two. The plasticized metal moves downward and outwards under the action of a clockwise rotating left screw stirring needle. With the increase of agitation needle series, the number of plasticized metal moving from the center to the periphery increases, so the third stage mixing head is easy to cause hole defects. With the increase of MWCNTs content, the surface crack of the bar increases, and the tensile strength increases first and then decreases. When the volume fraction of MWCNTs is 1.28, the tensile strength increases by nearly 20% compared with the base metal. The possible reason for the increase of the tensile strength is that the internal stress tends to homogenize. When the composite bar is formed well and the tensile strength is 184MPa, compared with the base metal, the directional arrangement of the reinforcing phase is the main reason for the increase of the strength of the composite. The excessive breakage of the composite leads to the decrease of the strength of the composite.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB333

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