NER: Synthesis of Metal Matrix-Nanoparticle Composites by Stir Mixing

本计画将探讨利用凝固制程（包括搅拌混合技术）合成金属基奈米粒子复合材料。在使用搅拌混合工艺合成复合材料中，将存在不确定性，例如纳米尺寸颗粒的引入和分散的困难、由于纳米尺寸颗粒的高表面积而导致的熔体粘度的增加以及纳米尺寸颗粒的浮选/沉降速度。 纳米颗粒的加入可以使金属基纳米复合材料具有更好的力学性能，包括高强度、高疲劳和高蠕变性能，本研究将发展纳米颗粒在铝熔体中的混合技术，并确定最佳的凝固工艺以获得纳米颗粒在铸造材料中的均匀分布。将优化混合条件，包括纳米尺寸颗粒的进料速率、搅拌器速度、颗粒体积分数、润湿剂、超声能量和熔体温度，以使纳米尺寸颗粒均匀分布。含有纳米尺寸颗粒的熔体的流动性和纳米尺寸颗粒的浮选或沉降速度也将由颗粒在熔体和基质中的最终分布确定。将分析凝固的微观结构和纳米颗粒在基体中的分布，以了解纳米颗粒存在下的成核和生长行为。将测量与加工变量相关的选定性能，包括密度、模量和压缩性能。 预计这项工作的结果可以导致纳米复合材料铸件的技术转让。

This project will explore the synthesis of metal-matrix nanoparticle composites using solidification processes, including stir mixing technique. In the synthesis of the composites using the stir mixing process, there will be uncertainties such as difficulty in the introduction and dispersion of nanosize particles, increase in viscosity in melts due to high surface area of nanosize particles, and flotation/sedimentation velocities of nanosize particles. The incorporation of nanoparticles can lead to metal-matrix nanocomposites with improved mechanical properties, including high strength, high fatigue and high creep properties.In this research, mixing technologies will be developed to mix nanosize particles in aluminum melts, and optimum solidification process will be identified for obtaining a uniform distribution of nanosize particles in cast materials. Mixing conditions, including feeding rate of nanosize particles, stirrer speed, particle volume fraction, wetting agent, ultrasonic energy, and melt temperature will be optimized for a uniform distribution of nanosize particles. The fluidity of a melt containing nanosize particles and velocities of flotation or settling of nanosize particle will also be determined from the final distribution of the particles in the melt and in the matrix. The solidified microstructure and the distribution of nanoparticles in the matrix will be analyzed to understand nucleation and growth behavior in the presence of nanosize particles. Selected properties, including the density, modulus and compressive properties will be measured related to processing variables. It is anticipated that the results of this work can lead to technology transfer for nanocomposite castings.