【摘要】：采用粉末冶金法結(jié)合熱擠壓制備了不同含量的碳納米管(Carbon nanotubes,CNTs)、石墨烯(Graphene nanoplates,GNPs)及兩者混雜增強(qiáng)AZ31鎂基復(fù)合材料。利用光學(xué)顯微鏡、X射線衍射、能譜分析和掃描電子顯微鏡等對復(fù)合材料進(jìn)行表征。研究了 CNTs、GNPs加入含量對顯微組織、致密度、力學(xué)性能、導(dǎo)電性能和摩擦性能的影響;考察了過程控制劑含量對球磨結(jié)果的影響;為了進(jìn)一步發(fā)揮增強(qiáng)體的效果,探索了不同混雜比例CNTs/GNPs增強(qiáng)體對復(fù)合材料組織和性能的影響;進(jìn)行了復(fù)合材料的等徑角擠壓試驗(yàn)。主要結(jié)果如下:當(dāng)過程控制劑硬脂酸的含量為0.3wt.%時(shí),球磨后粉末顆粒最均勻,擠壓后材料的抗壓強(qiáng)度、硬度、致密度和導(dǎo)電性能最高。隨著CNTs含量的增加,復(fù)合材料的晶粒尺寸先減小后增大、強(qiáng)度先升高后降低、延伸率和導(dǎo)電率逐漸降低、抗摩擦性能逐漸提高。當(dāng)CNTs的含量為1wt.%時(shí),晶粒尺寸比基體合金降低19%;其強(qiáng)度稍有升高;硬度和斷裂應(yīng)變比基體提高10%和13%;當(dāng)摩擦中的法向載荷為50N時(shí),摩擦系數(shù)和磨損量分別降低15%和39%。GNPs的含量越高,復(fù)合材料的抗拉強(qiáng)度、顯微硬度和抗摩擦性能也越高、延伸率、密度和導(dǎo)電率越低。當(dāng)GNPs的含量為0.5wt.%,擠壓方向的晶粒尺寸比基體降低12%;抗拉強(qiáng)度、延伸率、抗壓強(qiáng)度、硬度分別為269MPa,13.8%,480MPa和83.5HV;當(dāng)法向載荷為50N時(shí),摩擦系數(shù)和磨損量分別降低9%和25%。CNTs/GNPs混雜增強(qiáng)比單一增強(qiáng)的綜合力學(xué)性能好。尤其當(dāng)混雜比例為1:1(CNTs和GNPs的含量分別為0.5wt.%)時(shí),復(fù)合材料表現(xiàn)出優(yōu)異的協(xié)同效應(yīng)。該復(fù)合材料的晶粒均勻細(xì)小;抗拉強(qiáng)度、硬度和延伸率最高,分別為315MPa、88.7HV和18.5%,比基體合金提升了 11%、9%和28%;導(dǎo)電率為基體的75%;當(dāng)法向載荷為50N時(shí),復(fù)合材料的摩擦系數(shù)和磨損量降低了 10%和27%。ECAP變形一道次后,組織明顯細(xì)化,屈服強(qiáng)度和抗壓強(qiáng)度有較明顯提升、塑性保持不變�；祀s比例為1:1(CNTs和GNPs的含量分別為0.5wt.%)復(fù)合材料的屈服強(qiáng)度和抗壓強(qiáng)度分別為247MPa和507MPa,比擠壓態(tài)提升了 14%和9%,比擠壓態(tài)基體合金提升了 14%和12%。
[Abstract]:Carbon nanotubes (Carbon nanotubes,CNTs), graphene (Graphene nanoplates,GNPs) and mixed AZ31 magnesium matrix composites were prepared by powder metallurgy and hot extrusion. The composite was characterized by X-ray diffraction, energy spectrum analysis and scanning electron microscope. The effects of the content of CNTs,GNPs on microstructure, density, mechanical properties, electrical conductivity and friction properties were studied. The effect of process control agent content on the results of ball milling was investigated. The effects of CNTs/GNPs reinforcements with different hybrid ratios on the microstructure and properties of the composites were investigated, and the equal path angular extrusion tests were carried out. The main results are as follows: when the content of stearic acid is 0.3 wt.%, the powder particle is the most uniform after ball milling, and the compressive strength, hardness, density and electrical conductivity of the extruded material are the highest. With the increase of CNTs content, the grain size of the composites decreases first and then increases, the strength increases first and then decreases, the elongation and conductivity decrease gradually, and the friction resistance increases gradually. When the content of CNTs is 1 wt.%, the grain size is 19% lower than that of the base alloy, the strength is slightly higher, the hardness and fracture strain are 10% and 13% higher than that of the matrix, and when the normal load in friction is 50 N, The higher the content of 39%.GNPs and friction coefficient, the higher the tensile strength, microhardness and friction resistance of the composites, and the lower the elongation, density and conductivity of the composites. When the content of GNPs is 0.5 wt., the grain size in the extrusion direction is 12% lower than that of the matrix, and the tensile strength, elongation, compressive strength and hardness are 269mpa, 13.8MPa and 83.5HVrespectively, and when the normal load is 50N, the tensile strength, elongation, compressive strength and hardness are respectively 480MPa and 83.5HV. The friction coefficient and wear rate were reduced by 9% and 25%.CNTs/GNPs respectively. Especially when the hybrid ratio is 1:1 (the content of CNTs and GNPs is 0.5 wt.%), the composite shows excellent synergistic effect. The composite has the highest tensile strength, hardness and elongation, which are 315MPA, 88.7HV and 18.5, which are 11.9% and 28% higher than the matrix alloy, the conductivity of which is 75%, and when the normal load is 50N, the composite has the highest tensile strength, hardness and elongation of the composite, and the tensile strength, hardness and elongation of the composite are the highest (315MPA, 88.7HV and 18.5HV, respectively). When the friction coefficient and wear capacity of the composites are reduced by 10% and 27%.ECAP deformation, the microstructure is refined, the yield strength and compressive strength are obviously increased, and the plasticity remains unchanged. The yield strength and compressive strength of the composite at 1:1 (CNTs and GNPs = 0.5wt.%) are 247MPa and 507MPA, respectively, which are 14% and 9% higher than those of extruded state and 14% and 12% higher than that of extruded matrix alloy.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB333

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