The effect of reinforcement volume ratio on porosity and thermal conductivity in Al-Mgo composites

Abstract

In this study, the effects of reinforcement volume ratios (RVR) on composite structure and thermal conductivity were examined in Al-MgO reinforced metal matrix composites (MMCs) of 5%, 10% and 15% RVR produced by melt stirring. In the production of composites, EN AW 1050A aluminum alloy was used as the matrix material and MgO powders with particle size of -105 µm were used as the reinforcement material. For every composite specimen was produced at 500 rev/min stirring speed, at 750 °C liquid matrix temperature and 4 minutes stirring time. Composite samples were cooled under normal atmosphere. Then, microstructures of the samples were determined and evaluated by using Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analysis. In general, it was observed that the reinforcement exhibited a homogeneous distribution. Furthermore, it was determined that the increase in the RVR increased porosity. From the Scanning Electron Microscope images, a thermal Ansys model was generated to determine effective thermal conductivity. Effective thermal conductivity of Al-MgO composites increased with the decrease in reinforcement volume ratio.

Synthesis of boron carbide reinforced aluminum castings through mechanical stir casting

“…42 Porosity can affect wetting of ceramic-based when casting with aluminum matrix and can decrease the thermal conductivity of aluminum. 43 Brittle ingots can also result from excessive powder agglomeration in the melt when boron carbide is added in large amounts. To prevent this, slow dispersion rates were established as previously discussed.…”

Effect of tempering on thermal analysis of Al-Ti-Si alloy and its composites

“…The reinforcement material MgO was generally distributed homogeneously as shown in Fig.2b. This situation can be clarified by precipitation of reinforcement during the cooling of liquid mixture due to its higher specific gravity than that of the matrix material Al [14]. There is a lower chance or lower amount of Al 3 Ti phase form in presence of MgO in Al-Ti alloy because most of Al are react with oxygen and converting to Al 2 O 3 During the casting.…”

An Overview of the Interactions Between Reinforcements and Al Matrices with Si, Cu And Mg as Alloying Elements in Aluminum Matrix Composites: Case of Oxide Reinforcements

“…For MMSF characteristics of the hollow reinforcements such as porosity percentage and wall thickness also affect the mechanical properites 45 . Among the most reported reinforcements for AMC are carbides (SiC, B 4 C, WC, TiC) [46][47][48][49][50][51][52] , oxides (Al 2 O 3 , SiO 2 , TiO 2 , ZrO 2 , Y 2 O 3 , MgO, CeO 2 ) [53][54][55][56][57][58] , nitrides (Si 3 N 4 , BN) [59][60][61] and Carbon Nanotubes (CNTs) [62][63][64][65][66][67] . For the case of syntactic foams there have been mainly reported metallic or ceramics hollow spheres, being Fe, SiC, SiO 2 and Al 2 O 3 the most used [40][41][42][43][44][45][68][69][70][71][72] .…”