Preparation of high thermal conductivity diamond/aluminum composites by vacuum hot pressing
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摘要: 以纯铝粉末和金刚石为基体材料,采用真空热压固相烧结方式制备出热导率为677 W/(m·K)的高导热金刚石/铝复合材料。利用激光导热仪、热膨胀仪对金刚石/铝复合材料性能进行表征,并通过对制备温度、保温时间及金刚石基本颗粒尺寸的调控来优化制备工艺。研究发现:随制备温度升高,金刚石/铝复合材料的密度及致密度均有所提高,其热导率呈先升后降的趋势,当制备温度为650 ℃时,热导率达到526.2 W/(m·K)。随着保温时间由30 min增加至120 min,金刚石/铝复合材料的密度、致密度和热导率均增大,致密度达到99.1%,热导率达到566.7 W/(m·K)。当金刚石基本颗粒尺寸由20 μm增加至500 μm时,金刚石/铝复合材料的密度、致密度先增大后减小;在金刚石基本颗粒尺寸为200 μm时,密度达到最大,分别为3.06 g/cm3和98.4%;热导率随金刚石基本颗粒尺寸逐渐增大,在金刚石基本颗粒尺寸为500 μm时,热导率达到677.5 W/(m·K),为目前最高增强效率。故通过工艺控制可以有效提高铝基体与金刚石的结合,减少其界面空隙,进而制备出高热导率金刚石/铝复合材料。Abstract: A high heat-conducting diamond/aluminum composite material with thermal conductivity of 677 W/(m·K) was prepared by vacuum hot-pressing solid-phase sintering. The properties of the diamond/aluminum composite were characterized by laser thermal conductivity instrument and thermal expansion instrument. The preparation process was optimized by modifying the preparation temperature, holding time and diamond particle size. It was noted that the density and relative density of diamond/aluminum composite increased with the increase of the preparation temperature, and the thermal conductivity first rose and then fell. When the preparation temperature was 650 ℃, the thermal conductivity reached 526.2 W/(m·K). When the heat preservation time increased from 30 minutes to 120 minutes, the density, the relative density and the thermal conductivity of diamond/aluminum composite materials all increased to the density of 99.1% and the thermal conductivity of 566.7 W/(m·K). When the size of diamond particle increased from 20 μm to 500 μm, the density and relative density of diamond/aluminum composite first increased and then decreased. When the size of diamond particle is 200 μm, the density and relative density reached their maximum values, namely 3.06 g/cm3 and 98.4%. The thermal conductivity increased with the increase of diamond size, and the thermal conductivity reached the highest 677.5 W/(m·K) when using 500 μm diamond particles as thermal conductive fillers. Therefore, high-density diamond/aluminum composite material prepared by vacuum hot pressing method can effectively improve the combination of aluminum matrix and diamond through process control, reduce interfacial void, and then prepare high thermal conductivity diamond/aluminum composite material.
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