文章信息/Info

Title:

Study on Thermal Conductivity of Magnesium Matrix Composites Reinforced by Carbon Nano-tubes

文章編號:

1674-3962(2020)01-0012-07

作者:

杜文博; 侯江濤; 孟繁婧; 李淑波

（北京工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，北京，100124）

Author(s):

DU Wenbo;  HOU Jiangtao;  MENG Fanjing;  LI Shubo

(College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China)

關(guān)鍵詞:

碳納米管; 鎂合金; 復(fù)合材料; 導(dǎo)熱性能; 顯微組織

Keywords:

Carbon Nano-tubes;  Magnesium Alloys;  Composites;  Thermal Conductivity;  Microstructures

分類號:

TG146.22；TB333

DOI:

10.7502/j.issn.1674-3962.201907023

文獻(xiàn)標(biāo)志碼:

A

摘要:

鎂及其合金是目前最輕的金屬結(jié)構(gòu)材料，合金化雖然提升了鎂合金的力學(xué)性能，但導(dǎo)致其導(dǎo)熱性能嚴(yán)重下降，限制了鎂合金的應(yīng)用。碳納米管（CNTs）因具有優(yōu)異的力學(xué)、熱學(xué)等性能，是最理想的增強(qiáng)體之一，可以用于改善鎂合金的力學(xué)性能和熱學(xué)性能。采用粉末冶金法分別以純Mg、Mg-9Al合金、Mg-6Zn合金為基體制備了不同CNTs含量的鎂基復(fù)合材料，利用光學(xué)顯微鏡、掃描電子顯微鏡、透射電子顯微鏡對復(fù)合材料微觀組織、基體與增強(qiáng)體界面及析出相進(jìn)行表征，并對復(fù)合材料的拉伸性能和熱學(xué)性能進(jìn)行測試。研究結(jié)果表明，當(dāng)CNTs質(zhì)量分?jǐn)?shù)不超過1.0%時(shí)，可提高純鎂基復(fù)合材料的導(dǎo)熱性能，力學(xué)性能僅有稍微降低；將CNTs添加到Mg-9Al合金中，可以促進(jìn)納米尺度β-Mg17Al12相在CNTs周圍析出，降低了Al在Mg基體中的固溶度，使CNTs/Mg-9Al復(fù)合材料的導(dǎo)熱性能有所提高。此外，在CNTs/Mg-6Zn復(fù)合材料界面處存在C原子和Mg原子的相互嵌入?yún)^(qū)，這種嵌入型界面不僅有利于復(fù)合材料力學(xué)性能的提高，也使CNTs起到加速電子移動(dòng)的“橋”的作用，有利于該復(fù)合材料熱導(dǎo)率的提高。當(dāng)CNTs質(zhì)量分?jǐn)?shù)為0.6%時(shí)，CNTs/Mg-6Zn復(fù)合材料具有較為優(yōu)異的熱學(xué)性能和力學(xué)性能，其熱導(dǎo)率為127.0 W/(m·K)，抗拉強(qiáng)度為303.0 MPa，屈服強(qiáng)度為204.0 MPa，伸長率為5.0%。

Abstract:

Currently, magnesium (Mg) and its alloys are the lightest structural metallic materials. Although the mechanical properties of Mg alloys can be improved by adding alloy elements, it causes a significant reduction of thermal property. Therefore, the application of Mg alloys is limited. Carbon nano-tubes (CNTs) are one of the most ideal reinforcements due to their excellent mechanical and thermal properties. They can be used to improve the mechanical and thermal properties of Mg alloys. Using pure Mg, Mg-9Al and Mg-6Zn as matrixes, the magnesium matrix composites with various CNTs contents were fabricated via the powder metallurgy method. The microstructures , interfaces between CNTs and matrix as well as precipitated phases of composites were characterized by OM, SEM and TEM. Moreover, the mechanical and thermal properties of composites were measured. Results indicate that the thermal conductivities of CNTs/Mg composites are enhanced with CNTs content less than 1.0wt%, while their mechanical properties only have a slight decrease. As CNTs are added into Mg-9Al alloy, a few nano-sized β-Mg17Al12 phases precipitates around CNTs. It has reduced the solid solubility of Al atom in Mg matrix, so that the thermal conductivity of CNTs/Mg-9Al composite increases. In CNTs/Mg��6Zn composites, there is an area where C and Mg atoms have embedded in each other at the interface. On the one hand, the embedding area coud improve the mechanical properties of CNTs/Mg-6Zn composite. On the other hand, it could make CNTs as a “bridge” to accelerate the movement of electrons, accordingly increasing the thermal conductivity of composites. When the CNTs content is 0.6wt%, CNTs/Mg-6Zn composite has relatively excellent thermal and mechanical properties. Its thermal conductivity is 127.0 W/(m·K), and its ultimate tensile strength is 303.0 MPa, tensile yield strength is 204.0 MPa and elongation is 5.0%.