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Special Issue "Microwave Processing of Materials"

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Manufacturing Processes and Systems".

Deadline for manuscript submissions: closed (31 July 2013)

Special Issue Editor

Guest Editor
Prof. Dr. Dinesh Agrawal (Website)

Microwave Processing and Engineering Center 107 Materials Research Laboratory The Pennsylvania State University University Park, PA 16802 USA
Interests: microwave processing of ceramics; composites; metals; etc., low thermal expansion materials; ceramic processing; rad-waste management

Special Issue Information

Dear Colleagues,

The “Materials” Journal’s special issue on “Microwave Processing of Materials”invites the original research articles and comprehensive reviews on the latest developments in the application of microwave energy in materials processing. Microwave processing of materials is emerging as an innovative technology for future, applicable to many diverse fields and variety of materials. This issue will focus especially on ceramics, metals, composites, biomaterials, and nanomaterials. However, manuscripts on other fields related to the application of microwaves in chemistry, waste processing and alternative and unconventional energy sources will also be considered. The volume will address the details of synthesis and processing, characterization, commercialization, equipment design and modeling, and theories of microwave energy-matter interactions to explain the results.

Prof. Dr. Dinesh Agrawal
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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Keywords

  • microwave energy
  • ceramics
  • steel
  • nanomaterials
  • microwave theories and modeling
  • synthesis
  • sintering

Published Papers (7 papers)

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Research

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Open AccessArticle Equivalent Electromagnetic Constants for Microwave Application to Composite Materials for the Multi-Scale Problem
Materials 2013, 6(11), 5367-5381; doi:10.3390/ma6115367
Received: 31 July 2013 / Revised: 18 October 2013 / Accepted: 8 November 2013 / Published: 21 November 2013
Cited by 1 | PDF Full-text (846 KB) | HTML Full-text | XML Full-text
Abstract
To connect different scale models in the multi-scale problem of microwave use, equivalent material constants were researched numerically by a three-dimensional electromagnetic field, taking into account eddy current and displacement current. A volume averaged method and a standing wave method were used [...] Read more.
To connect different scale models in the multi-scale problem of microwave use, equivalent material constants were researched numerically by a three-dimensional electromagnetic field, taking into account eddy current and displacement current. A volume averaged method and a standing wave method were used to introduce the equivalent material constants; water particles and aluminum particles are used as composite materials. Consumed electrical power is used for the evaluation. Water particles have the same equivalent material constants for both methods; the same electrical power is obtained for both the precise model (micro-model) and the homogeneous model (macro-model). However, aluminum particles have dissimilar equivalent material constants for both methods; different electric power is obtained for both models. The varying electromagnetic phenomena are derived from the expression of eddy current. For small electrical conductivity such as water, the macro-current which flows in the macro-model and the micro-current which flows in the micro-model express the same electromagnetic phenomena. However, for large electrical conductivity such as aluminum, the macro-current and micro-current express different electromagnetic phenomena. The eddy current which is observed in the micro-model is not expressed by the macro-model. Therefore, the equivalent material constant derived from the volume averaged method and the standing wave method is applicable to water with a small electrical conductivity, although not applicable to aluminum with a large electrical conductivity. Full article
(This article belongs to the Special Issue Microwave Processing of Materials)
Open AccessArticle Vanadium Pentoxide-Based Composite Synthesized Using Microwave Water Plasma for Cathode Material in Rechargeable Magnesium Batteries
Materials 2013, 6(10), 4514-4522; doi:10.3390/ma6104514
Received: 26 July 2013 / Revised: 6 September 2013 / Accepted: 6 October 2013 / Published: 11 October 2013
Cited by 7 | PDF Full-text (522 KB) | HTML Full-text | XML Full-text
Abstract
Multivalent cation rechargeable batteries are expected to perform well as high-capacity storage devices. Rechargeable magnesium batteries have an advantage in terms of resource utilization and safety. Here, we report on sulfur-doped vanadium pentoxide (S-V2O5) as a potential material [...] Read more.
Multivalent cation rechargeable batteries are expected to perform well as high-capacity storage devices. Rechargeable magnesium batteries have an advantage in terms of resource utilization and safety. Here, we report on sulfur-doped vanadium pentoxide (S-V2O5) as a potential material for the cathodes of such a battery; S-V2O5 showed a specific capacity of 300 mAh·g−1. S-V2O5 was prepared by a method using a low-temperature plasma generated by carbon felt and a 2.45 GHz microwave generator. This study investigates the ability of S-V2O5 to achieve high capacity when added to metal oxide. The highest recorded capacity (420 mAh·g−1) was reached with MnO2 added to composite SMn-V2O5, which has a higher proportion of included sulfur than found in S-V2O5. Results from transmission electron microscopy, energy-dispersive X-ray spectroscopy, Micro-Raman spectroscopy, and X-ray photoelectron spectroscopy show that the bulk of the SMn-V2O5 was the orthorhombic V2O5 structure; the surface was a xerogel-like V2O5 and a solid solution of MnO2 and sulfur. Full article
(This article belongs to the Special Issue Microwave Processing of Materials)
Open AccessArticle Observations of Ball-Lightning-Like Plasmoids Ejected from Silicon by Localized Microwaves
Materials 2013, 6(9), 4011-4030; doi:10.3390/ma6094011
Received: 1 August 2013 / Revised: 2 September 2013 / Accepted: 3 September 2013 / Published: 11 September 2013
Cited by 9 | PDF Full-text (3442 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents experimental characterization of plasmoids (fireballs) obtained by directing localized microwave power (<1 kW at 2.45 GHz) onto a silicon-based substrate in a microwave cavity. The plasmoid emerges up from the hotspot created in the solid substrate into the air [...] Read more.
This paper presents experimental characterization of plasmoids (fireballs) obtained by directing localized microwave power (<1 kW at 2.45 GHz) onto a silicon-based substrate in a microwave cavity. The plasmoid emerges up from the hotspot created in the solid substrate into the air within the microwave cavity. The experimental diagnostics employed for the fireball characterization in this study include measurements of microwave scattering, optical spectroscopy, small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Various characteristics of these plasmoids as dusty plasma are drawn by a theoretical analysis of the experimental observations. Aggregations of dust particles within the plasmoid are detected at nanometer and micrometer scales by both in-situ SAXS and ex-situ SEM measurements. The resemblance of these plasmoids to the natural ball-lightning (BL) phenomenon is discussed with regard to silicon nano-particle clustering and formation of slowly-oxidized silicon micro-spheres within the BL. Potential applications and practical derivatives of this study (e.g., direct conversion of solids to powders, material identification by breakdown spectroscopy (MIBS), thermite ignition, and combustion) are discussed. Full article
(This article belongs to the Special Issue Microwave Processing of Materials)
Figures

Open AccessArticle Synthesis and Characterization of Nano Boron Nitride Reinforced Magnesium Composites Produced by the Microwave Sintering Method
Materials 2013, 6(5), 1940-1955; doi:10.3390/ma6051940
Received: 11 April 2013 / Revised: 3 May 2013 / Accepted: 6 May 2013 / Published: 10 May 2013
Cited by 13 | PDF Full-text (2728 KB) | HTML Full-text | XML Full-text
Abstract
In this study, magnesium composites with nano-size boron nitride (BN) particulates of varying contents were synthesized using the powder metallurgy (PM) technique incorporating microwave-assisted two-directional sintering followed by hot extrusion. The effect of nano-BN addition on the microstructural and the mechanical behavior [...] Read more.
In this study, magnesium composites with nano-size boron nitride (BN) particulates of varying contents were synthesized using the powder metallurgy (PM) technique incorporating microwave-assisted two-directional sintering followed by hot extrusion. The effect of nano-BN addition on the microstructural and the mechanical behavior of the developed Mg/BN composites were studied in comparison with pure Mg using the structure-property correlation. Microstructural characterization revealed uniform distribution of nano-BN particulates and marginal grain refinement. The coefficient of thermal expansion (CTE) value of the magnesium matrix was improved with the addition of nano-sized BN particulates. The results of XRD studies indicate basal texture weakening with an increase in nano-BN addition. The composites showed improved mechanical properties measured under micro-indentation, tension and compression loading. While the tensile yield strength improvement was marginal, a significant increase in compressive yield strength was observed. This resulted in the reduction of tension-compression yield asymmetry and can be attributed to the weakening of the strong basal texture. Full article
(This article belongs to the Special Issue Microwave Processing of Materials)
Open AccessArticle Tensile and Compressive Responses of Ceramic and Metallic Nanoparticle Reinforced Mg Composites
Materials 2013, 6(5), 1826-1839; doi:10.3390/ma6051826
Received: 2 April 2013 / Revised: 24 April 2013 / Accepted: 27 April 2013 / Published: 7 May 2013
Cited by 5 | PDF Full-text (2065 KB) | HTML Full-text | XML Full-text
Abstract
In the present study, room temperature mechanical properties of pure magnesium, Mg/ZrO2 and Mg/(ZrO2 + Cu) composites with various compositions are investigated. Results revealed that the use of hybrid (ZrO2 + Cu) reinforcements in Mg led to enhanced mechanical [...] Read more.
In the present study, room temperature mechanical properties of pure magnesium, Mg/ZrO2 and Mg/(ZrO2 + Cu) composites with various compositions are investigated. Results revealed that the use of hybrid (ZrO2 + Cu) reinforcements in Mg led to enhanced mechanical properties when compared to that of single reinforcement (ZrO2). Marginal reduction in mechanical properties of Mg/ZrO2 composites were observed mainly due to clustering of ZrO2 particles in Mg matrix and lack of matrix grain refinement. Addition of hybrid reinforcements led to grain size reduction and uniform distribution of hybrid reinforcements, globally and locally, in the hybrid composites. Macro- and micro- hardness, tensile strengths and compressive strengths were all significantly increased in the hybrid composites. With respect to unreinforced magnesium, failure strain was almost unchanged under tensile loading while it was reduced under compressive loading for both Mg/ZrO2 and Mg/(ZrO2 + Cu) composites. Full article
(This article belongs to the Special Issue Microwave Processing of Materials)
Open AccessArticle Enhanced Microwave Absorption Properties of α-Fe2O3-Filled Ordered Mesoporous Carbon Nanorods
Materials 2013, 6(4), 1520-1529; doi:10.3390/ma6041520
Received: 15 March 2013 / Revised: 3 April 2013 / Accepted: 7 April 2013 / Published: 15 April 2013
Cited by 18 | PDF Full-text (1217 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A novel kind of α-Fe2O3-filled ordered mesoporous carbon nanorods has been synthesized by a facial hydrothermal method. Compared with dendritic α-Fe2O3 micropines, both a broader effective absorption range—from 10.5 GHz to 16.5 GHz with reflection [...] Read more.
A novel kind of α-Fe2O3-filled ordered mesoporous carbon nanorods has been synthesized by a facial hydrothermal method. Compared with dendritic α-Fe2O3 micropines, both a broader effective absorption range—from 10.5 GHz to 16.5 GHz with reflection loss (RL) less than −10 dB—and a thinner matching thickness of 2.0 mm have been achieved in the frequency range 2–18 GHz. The enhanced microwave absorption properties evaluated by the RL are attributed to the enhanced dielectric loss resulting from the intrinsic physical properties and special structures. Full article
(This article belongs to the Special Issue Microwave Processing of Materials)

Other

Jump to: Research

Open AccessCase Report Optimization of Microwave-Based Heating of Cellulosic Biomass Using Taguchi Method
Materials 2013, 6(8), 3404-3419; doi:10.3390/ma6083404
Received: 15 May 2013 / Revised: 29 July 2013 / Accepted: 1 August 2013 / Published: 9 August 2013
Cited by 4 | PDF Full-text (393 KB) | HTML Full-text | XML Full-text
Abstract
This study discusses the application of microwave-based heating for the pretreatment of biomass material, with Pennisetum purpureum selected for pretreatment. The Taguchi method was used to plan optimization experiments for the pretreatment parameter levels, and to measure the dynamic responses. With a [...] Read more.
This study discusses the application of microwave-based heating for the pretreatment of biomass material, with Pennisetum purpureum selected for pretreatment. The Taguchi method was used to plan optimization experiments for the pretreatment parameter levels, and to measure the dynamic responses. With a low number of experiments, this study analyzed and determined a parameter combination in which Pennisetum purpureum can be rapidly heated to 190 °C. The experimental results suggested that the optimal parameter combination is: vessel capacity of 150 mL (level 2), heating power of 0.5 kW (level 1), and mass of Pennisetum purpureum of 5 g (level 1). The mass of Pennisetum purpureum is a key factor affecting system performance. An eight-order ARX model (Auto-Regressive eXogeneous) was representative of the actual system performance, and the fit was 99.13%. The results proved that microwave-based heating, with the assistance of the Taguchi method for pretreatment of the biomass material, can reduce the parameter combination variations. Full article
(This article belongs to the Special Issue Microwave Processing of Materials)

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