Papers by Author: Yong Ha Park

Abstract: Carbon Nano Tube (CNT) reinforced AZ91 metal matrix composites (MMC) were fabricated by the squeeze infiltrated method. Properties of magnesium alloys have been improved by impurity reduction, surface treatment and alloy design, and thus the usage for the magnesium alloys has been extended recently. However there still remain barriers for the adaption of magnesium alloys for engineering materials. In this study, we report light-weight, high strength heat resistant magnesium matrix composites. Microstructural study and tensile test were performed for the squeeze infiltrated magnesium matrix composites. The wear properties were characterized and the possibility for the application to automotive power train and engine parts was investigated. It was found that the squeeze infiltration technique is a proper method to fabricate magnesium matrix composites reducing casting defects such as pores and matrix/reinforcement interface separation etc. Improved tensile and mechanical properties were obtained with CNT reinforcing magnesium alloys

Abstract: AZ31 Mg alloy matrix composites were fabricated by squeeze casting method to improve high temperature properties in this study. The results showed that Mg composites reinforced with Alborex and Ag revealed improved high temperature properties and mechanical properties compared with Mg alloys. High temperature hardness and flexural strength were increased with reinforcement of Alborex, and further increase was obtained with addition of Ag. Also, Alborex reinforced AZ31 containing Ag Mg matrix composite exhibited greater improvement on creep properties. Therefore Mg composites reinforced with Alborex containing Ag were better than those reinforced with Alborex in mechanical properties and high temperature properties.

Abstract: A theoretical model is applied to the analysis of thermomechanical properties of Al-SiCp FGMs in this study. Functionally graded Al-SiCp composites (Al-SiCp FGMs) consisted with 10 layers gradually changing volume fractions of Al and SiCp were fabricated using the pressureless infiltration technique. Al-SiCp FGMs plates of total thickness of 3mm, 5mm and 7mm with fairly uniform distribution and compositional gradient of SiCp reinforcement in the Al matrix throughout the thickness was successfully fabricated. The curvature of Al-SiCp FGM plates was measured to check the internal stress distribution predicted via a theoretical model for the analysis of thermomechanical deformation. The evolution of curvature and also internal stresses in response to temperature variations could be predicted for the different combinations of geometric thickness of FGM plates. Theoretical prediction of thermally induced stress distribution makes it possible to design FGM structures without any critical failure during the usage of them.