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Full-Text Articles in Engineering
Design Of Functionally Graded Materials Using Transient Nonlinear Simulations And Genetic Algorithm Optimization, Senthil Vel
Design Of Functionally Graded Materials Using Transient Nonlinear Simulations And Genetic Algorithm Optimization, Senthil Vel
University of Maine Office of Research Administration: Grant Reports
The objective of this research is to develop a robust methodology for the design of functionally graded materials (FGMs). FGMs are advanced composite materials that are engineered to have a smooth spatial variation of material properties. This is achieved by gradually varying the relative volume fractions and microstructure of the material constituents during fabrication. FGM components typically exhibit smaller stresses and higher factors of safety than discretely bonded monolithic materials. The aim of this research project is to create a unified framework for the simultaneous optimization of structural shape, compositional profile and microstructure of metal/ceramic FGMs that are subjected to …
High Performance Zno Varistors Prepared From Nanocrystalline Precursors For Miniaturised Electronic Devices, Suresh Pillai, Declan Mccormack, John Kelly, Raghavendra Ramesh
High Performance Zno Varistors Prepared From Nanocrystalline Precursors For Miniaturised Electronic Devices, Suresh Pillai, Declan Mccormack, John Kelly, Raghavendra Ramesh
Articles
An industrially viable solution-based processing route using minimal amounts of solvent has been used to prepare bulk quantity nanopowders (average particle size 15.3 nm) for the fabrication of ZnO varistors. The xerogels, calcined powders and sintered materials were fully characterised. The preparation of varistors from nanopowders has been optimised by studying the effect of temperature on grain growth, densification and breakdown voltage. The varistors are prepared by sintering at 1050 C for 2 hours, a temperature that is significantly lower than that used in the current industrial process. Highly dense varistor discs prepared from the sintered material produce devices, with …
Effect Of Processing Schedule On The Microstructure And Texture Of 0.78wt% Cr Extra-Low-Carbon Steel, Elena V. Pereloma, Azdiar A. Gazder, John J. Jonas, Michael K. Miller, Christopher Hj Davies
Effect Of Processing Schedule On The Microstructure And Texture Of 0.78wt% Cr Extra-Low-Carbon Steel, Elena V. Pereloma, Azdiar A. Gazder, John J. Jonas, Michael K. Miller, Christopher Hj Davies
Faculty of Engineering - Papers (Archive)
An extra-low-carbon steel was alloyed with 0.78 wt% Cr and subjected to three different processing schedules involving: (i) warm rolling to 65 % reduction at 640°C, (ii) warm rolling to 80% reduction at 580°C and (iii) warm rolling to 65% reduction at 640°C followed by cold rolling to 40% reduction. Increasing the severity of the deformation resulted in an increase in the number of grains containing in-grain shear bands. X-ray bulk texture analysis indicates that the g -fibre intensity was slightly higher in the steel warm rolled at 580°C than at 640°C and after cold rolling. Transmission electron microscopy and …
A New Method Of Synthesizing Black Birnessite Nanoparticles: From Brown To Black Birnessite With Nanostructures, Shizhi Qian, Marcos A. Cheney, Pradip K. Bhowmik, Sang W. Joo, Wensheng Hou, Joseph M. Okoh
A New Method Of Synthesizing Black Birnessite Nanoparticles: From Brown To Black Birnessite With Nanostructures, Shizhi Qian, Marcos A. Cheney, Pradip K. Bhowmik, Sang W. Joo, Wensheng Hou, Joseph M. Okoh
Mechanical Engineering Faculty Research
A new method for preparing black birnessite nanoparticles is introduced. The initial synthesis process resembles the classical McKenzie method of preparing brown birnessite except for slower cooling and closing the system from the ambient air. Subsequent process, including wet-aging at 7◦C for 48 hours, overnight freezing, and lyophilization, is shown to convert the brown birnessite into black birnessite with complex nanomorphology with folded sheets and spirals. Characterization of the product is performed by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), and N2 adsorption (BET) techniques. Wet-aging and lyophilization times are shown to …
Progress In Effect Of Jominy End Quench On The Microstructure And Mechanical Properties Of Cast Aluminum Alloys, Qingcai Liu, C. Lu, Joseph William Newkirk
Progress In Effect Of Jominy End Quench On The Microstructure And Mechanical Properties Of Cast Aluminum Alloys, Qingcai Liu, C. Lu, Joseph William Newkirk
Materials Science and Engineering Faculty Research & Creative Works
In this review, the current knowledge related to the relationship between the heat treatment process and the microstructure and mechanical properties of A356 aluminum alloys are summarized. The review also examines the use of the Jominy end quench (JEQ) specimen and its application to the examination of the effects of quench rate and subsequent processing. Using the design of experimental methods combined with the Jominy end quench technique, desired changes in microstructure and mechanical properties of alloys can be obtained. So, the experimental technique of the Jominy end quench was concerned in this work.