Date of Defense
11-11-2025 2:30 PM
Location
F1-1043
Document Type
Dissertation Defense
Degree Name
Doctor of Philosophy in Mechanical & Aerospace Engineering
College
COE
Department
Mechanical and Aerospace Engineering
First Advisor
Dr. Jaber Abu Qudeiri
Keywords
Aluminum alloy, aluminum metal matrix composites, stir casting, mechanical properties, material characterization.
Abstract
Aluminum matrix composites (AMCs) are extensively used in various industrial applications owing to their exceptional mechanical, material, and tribological properties. This led to the development of AMCs with every possible aluminum alloy as matrix, incorporated with various reinforcement materials to achieve desired material properties. There has been an increasing trend in the utilization of agricultural and industrial waste products as reinforcement material in AMCs. Date palm trees produce huge quantity of agricultural waste in different forms. Usually, these wastes are burned or disposed of in landfills which cause environmental pollution. Date palm agro-wastes can be incinerated to produce date palm ash, which can be reinforced with various aluminum alloys to develop sustainable AMCs with superior strength, hardness, wear properties and corrosion resistance. Fabrication of the composite can be done through stir casting method which is the most economical and effective AMC production technique. This doctoral research aims to develop a sustainable approach to improve the material properties of aerospace grade AA7075 aluminum alloy by reinforcing with heat treated date palm ash (DPA) powder. Date palm waste derived ash was used as a low-cost reinforcement after heat treating at 700 °C for 6 hours to eliminate volatile matter and enhance its thermal stability. Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis, and Fourier transform infrared (FTIR) spectroscopy confirmed that the heat-treated DPA can be effectively incorporated as a reinforcement in AA7075 alloy matrix. Aluminum matrix composites were fabricated through stir casting process with varying weight fractions of DPA (1 wt.%, 2 wt.%, and 3 wt.%). Two stage stirring process under inert gas atmosphere was adopted and vacuum assisted die casting was performed to fabricate defect free composites. Microstructural analysis revealed homogenous dispersion of reinforcement particles, grain refinement and good interfacial bonding between matrix and reinforcement up to 2 wt.% DPA addition. Consequently, these composites exhibited significant improvement in ultimate tensile strength (UTS), compression strength and hardness values compared to base alloy. However, further increase in reinforcement content resulted in non-uniform distribution of particulates, particle clustering, and poor wetting, which degraded the mechanical properties of AA7075- 3 wt.% DPA composite. Among the composites fabricated, AA7075- 2 wt.% DPA samples exhibited the highest improvement in mean Vickers hardness (27.74%), UTS (66.91%) and compression strength (34.17%) compared to the corresponding values of as-cast alloy. Incorporating DPA as reinforcement significantly enhanced the corrosion resistance of the material. Utilizing DPA reinforcement in AMCs enhances the material properties, valorizes agricultural waste, and offers a sustainable alternative to high-cost synthetic ceramic reinforcements.
Included in
DEVELOPMENT AND CHARACTERIZATION OF SUSTAINABLE ALUMINUM METAL MATRIX COMPOSITES WITH DATE PALM AGRO-RESIDUES AS REINFORCEMENT
F1-1043
Aluminum matrix composites (AMCs) are extensively used in various industrial applications owing to their exceptional mechanical, material, and tribological properties. This led to the development of AMCs with every possible aluminum alloy as matrix, incorporated with various reinforcement materials to achieve desired material properties. There has been an increasing trend in the utilization of agricultural and industrial waste products as reinforcement material in AMCs. Date palm trees produce huge quantity of agricultural waste in different forms. Usually, these wastes are burned or disposed of in landfills which cause environmental pollution. Date palm agro-wastes can be incinerated to produce date palm ash, which can be reinforced with various aluminum alloys to develop sustainable AMCs with superior strength, hardness, wear properties and corrosion resistance. Fabrication of the composite can be done through stir casting method which is the most economical and effective AMC production technique. This doctoral research aims to develop a sustainable approach to improve the material properties of aerospace grade AA7075 aluminum alloy by reinforcing with heat treated date palm ash (DPA) powder. Date palm waste derived ash was used as a low-cost reinforcement after heat treating at 700 °C for 6 hours to eliminate volatile matter and enhance its thermal stability. Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis, and Fourier transform infrared (FTIR) spectroscopy confirmed that the heat-treated DPA can be effectively incorporated as a reinforcement in AA7075 alloy matrix. Aluminum matrix composites were fabricated through stir casting process with varying weight fractions of DPA (1 wt.%, 2 wt.%, and 3 wt.%). Two stage stirring process under inert gas atmosphere was adopted and vacuum assisted die casting was performed to fabricate defect free composites. Microstructural analysis revealed homogenous dispersion of reinforcement particles, grain refinement and good interfacial bonding between matrix and reinforcement up to 2 wt.% DPA addition. Consequently, these composites exhibited significant improvement in ultimate tensile strength (UTS), compression strength and hardness values compared to base alloy. However, further increase in reinforcement content resulted in non-uniform distribution of particulates, particle clustering, and poor wetting, which degraded the mechanical properties of AA7075- 3 wt.% DPA composite. Among the composites fabricated, AA7075- 2 wt.% DPA samples exhibited the highest improvement in mean Vickers hardness (27.74%), UTS (66.91%) and compression strength (34.17%) compared to the corresponding values of as-cast alloy. Incorporating DPA as reinforcement significantly enhanced the corrosion resistance of the material. Utilizing DPA reinforcement in AMCs enhances the material properties, valorizes agricultural waste, and offers a sustainable alternative to high-cost synthetic ceramic reinforcements.