scholarly journals Manufacture of Glass Foam by Predominantly Direct Microwave Heating of Recycled Glass Waste

2019 ◽  
Vol 7 (4) ◽  
pp. 37-45
Author(s):  
Sorin Mircea AXINTE ◽  
Lucian Paunescu ◽  
Marius Florin Dragoescu ◽  
Ana Casandra Sebe
Keyword(s):  
Microwave Heating ◽  
Foam Glass ◽  
Weight Ratio ◽  
Original Method ◽  
Microwave Energy ◽  
Waste Glass ◽  
Conventional Heating ◽  
Thin Wall ◽  
Glass Waste ◽  
Materials Used

The paper presents authors’ contribution to the improvement of the manufacturing technique of foam glass using the microwave energy. Due to the physical and mechanical characteristics, this material, obtained by the sintering process of waste glass at high temperature, constitutes a viable replacer of existing similar materials, used especially in construction. Unlike the conventional heating methods used worldwide, the company Daily Sourcing & Research SRL Bucharest tested lately microwave heating techniques in the manufacturing process of foam glass. In the paper it is presented an original method based on the feature of the powder mixture composed by waste glass (over 97 wt.%) and the foaming agent (calcium carbonate) to absorb the microwave energy and convert it to heat since the ambient temperature, using a silicon carbide and silicon nitride (80/ 20 weight ratio) crucible with thin wall (2.5 mm), which allows both a preponderantly direct heating and partially an indirect heating of the material. The main parameters of the process (specific consumption of energy, heating speed, process temperature and duration) were significant improved compared to the previous experiments.

FOAM GLASS GRAVEL MADE OF RECYCLED GLASS WASTE AND SILICON CARBIDE BY MICROWAVE HEATING

2020 ◽  
Vol 26 (3) ◽  
pp. 173-180
Author(s):  
LUCIAN PAUNESCU ◽  
MARIUS FLORIN DRAGOESCU ◽  
SORIN MIRCEA AXINTE
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Mechanical Characteristics ◽  
Foam Glass ◽  
Specific Energy Consumption ◽  
Conventional Heating ◽  
Industrial Processes ◽  
Glass Waste ◽  
Recycled Glass ◽  
Physical And Mechanical Characteristics

The paper presents recent achievements in the microwave use for manufacturing foam glass gravel from recycled glass waste and silicon carbide. The aim was to obtain a product with physical and mechanical characteristics almost similar to those of industrially manufactured materials by conventional heating techniques, but with a higher energy efficiency. A foam glass with the thermal conductivity of 0.075 W/m·K and the compressive strength of 7.5 MPa was experimentally obtained. The specific energy consumption was of 1.0 kWh/kg comparable with the industrial processes and it could reach values up to 25% lower by using a high power industrial microwave equipment.

COMPARATIVE ANALYSIS OF THE FOAM GLASS GRAVEL TYPES EXPERIMENTALLY PRODUCED BY MICROWAVE IRRADIATION

2020 ◽  
Vol 26 (3) ◽  
pp. 58-68
Author(s):  
FELICIA COSMULESCU ◽  
LUCIAN PAUNESCU ◽  
MARIUS FLORIN DRAGOESCU ◽  
SORIN MIRCEA AXINTE
Keyword(s):  
Comparative Analysis ◽  
Heating Temperature ◽  
Foam Glass ◽  
Microwave Energy ◽  
Glass Waste ◽  
The World ◽  
Manufacturing Procedure ◽  
Maximum Heating Temperature ◽  
Sample Characteristics ◽  
Maximum Heating

The paper presents an unconventional technique for manufacturing foam glass gravel. The numerous experimental results obtained by the authors in the last year using various manufacturing recipes common in the world industrial production by conventional techniques were selected and subjected to a qualitative and energy efficiency comparative analysis, aiming to determine the best foam glass gravel manufacturing procedure under the conditions of the use of the microwave energy. The optimum recipe was composed of 83% glass waste, 1 % glycerol, 8 % sodium silicate and 8 % water. The maximum heating temperature reached 823 ºC with a very economical energy consumption of 0.88 kWh/kg. The sample characteristics were apparent density-0.24 g/cm3, porosity-89.1% with pore size between 0.3 - 0.6 mm, thermal conductivity-0.063 W/m·K and compressive strength - 5.9 MPa, almost similar to those industrially obtained.

scholarly journals The Analysis of Parametric Sensitivity Based on Designing and Optimization of a New Microwave Heating System

2017 ◽  
Vol 36 (8) ◽  
pp. 847-853 ◽  
Author(s):  
Hua Chen ◽  
Jin Zhang ◽  
Zebin Fan ◽  
Jinhui Peng ◽  
Shaohua Ju
Keyword(s):  
Microwave Heating ◽  
Heating System ◽  
Absorption Efficiency ◽  
Microwave Energy ◽  
Utilization Efficiency ◽  
Conventional Heating ◽  
Important Index ◽  
Energy Absorption Efficiency ◽  
Matching Performance ◽  
Heating Technology

AbstractMicrowave-assisted heating technology has become a popular alternative to conventional heating technologies because of its many advantages. However, the matching performance of microwave heating system is of particular concern because it provides an important index of the utilization efficiency of microwave energy. In this work, a new microwave heating system is designed by the theory of optical resonator in first. Then the comprehensive analysis of the mutual coupling of high sensitive geometrical and material parameters were investigated based on this new microwave heating system at 2.45 GHz. It is demonstrated that the thickness of materials dramatically influences microwave energy absorption efficiency and should be carefully considered and perhaps given priority. Moreover, it is shown that matching performance is the best when the titanium concentrates thickness at about 0.075 m.

scholarly journals Influence of glass residue on the properties of a mortar

2021 ◽  
Author(s):  
Ana Carolina Lisboa Machado ◽  
João Pedro Azeredo de Brito ◽  
João Victor Laurindo Siqueira ◽  
Diogo Pereira dos Santos Kropf
Keyword(s):  
Portland Cement ◽  
Silicon Oxide ◽  
Construction Materials ◽  
Waste Glass ◽  
Experimental Program ◽  
Multiple Use ◽  
Glass Waste ◽  
Water Absorption Coefficient ◽  
Materials Used ◽  
Main Components

The realization of actions aimed at sustainable development is unquestionable. As the technological improvement increases every day, the possibility of reusing different wastes to replace the use of natural resources in the development of construction materials is growing, since the wastes and byproducts from other industries have a significant representation in the volume of solid waste generated in the country. Aiming at the need to reuse waste, this work aimed to develop a multi-purpose mortar for use in construction with waste glass industry, in order to replace part of the binder material (Portland cement) by waste glass in percentages of 0, 5, 15 and 20%. The methodology used consisted of the experimental program that consists of the characterization of the materials used for the production of the multiple-use mortar, as well as the execution of technological tests of mortars in the fresh and hardened states. According to the results, it was possible to observe that the analyses made both on the residue and on the properties of the fresh and hardened state of the mixture, it was possible to verify that the influence of the residue in the mixture presented in its composition a 68% concentration of silicon oxide (silica), one of the main components of cement. In view of the aspects analyzed, it was concluded that the mortar with the replacement of Portland cement by glass waste showed better results regarding the porosity of the mortar since the capillary water absorption coefficient was the lowest among all mortars.

Microwave Synthesis of Lead-Barium Titanate

1994 ◽  
Vol 347 ◽  
Author(s):  
Jiping Cheng ◽  
Yi Fang ◽  
Dinesh K. Agrawal ◽  
Rustum Roy
Keyword(s):  
Air Pollution ◽  
Weight Loss ◽  
Barium Titanate ◽  
Microwave Heating ◽  
High Temperatures ◽  
Microwave Synthesis ◽  
Microwave Energy ◽  
Conventional Heating ◽  
Electronic Ceramics ◽  
Lead Oxides

ABSTRACTSince the volatilization of lead oxides is inevitable at high temperatures, the problems of maintaining stoichiometry and air pollution are of great concern in conventional synthesis of lead-barium titanate. We have demonstrated that the reaction between PbO, BaO and TiO2 could be greatly accelerated by using microwave energy. The synthesis of (PbxBa1-x)TiO3 can be completed in 10 minutes at about 750°C by microwave heating, while it takes at least 2 hours at 850°C in a conventional heating. The weight loss of PbO during microwave synthesis was much less than that in conventional synthesis. Thus the microwave synthesis technique may find wide applications for the preparation of various lead-containing materials in the production of electronic ceramics.

scholarly journals Microwaves and Heterogeneous Catalysis: A Review on Selected Catalytic Processes

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 246 ◽  
Author(s):  
Vincenzo Palma ◽  
Daniela Barba ◽  
Marta Cortese ◽  
Marco Martino ◽  
Simona Renda ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
Energy Saving ◽  
Microwave Heating ◽  
Microwave Radiation ◽  
Heterogeneous Catalysts ◽  
Conventional Heating ◽  
Specific Effects ◽  
Natural Choice ◽  
Future Challenges ◽  
Catalyzed Reactions

Since the late 1980s, the scientific community has been attracted to microwave energy as an alternative method of heating, due to the advantages that this technology offers over conventional heating technologies. In fact, differently from these, the microwave heating mechanism is a volumetric process in which heat is generated within the material itself, and, consequently, it can be very rapid and selective. In this way, the microwave-susceptible material can absorb the energy embodied in the microwaves. Application of the microwave heating technique to a chemical process can lead to both a reduction in processing time as well as an increase in the production rate, which is obtained by enhancing the chemical reactions and results in energy saving. The synthesis and sintering of materials by means of microwave radiation has been used for more than 20 years, while, future challenges will be, among others, the development of processes that achieve lower greenhouse gas (e.g., CO2) emissions and discover novel energy-saving catalyzed reactions. A natural choice in such efforts would be the combination of catalysis and microwave radiation. The main aim of this review is to give an overview of microwave applications in the heterogeneous catalysis, including the preparation of catalysts, as well as explore some selected microwave assisted catalytic reactions. The review is divided into three principal topics: (i) introduction to microwave chemistry and microwave materials processing; (ii) description of the loss mechanisms and microwave-specific effects in heterogeneous catalysis; and (iii) applications of microwaves in some selected chemical processes, including the preparation of heterogeneous catalysts.

scholarly journals A comparative study on quality parameters of pumpkin, melon and sunflower oils during thermal treatment

OCL ◽  
2019 ◽  
Vol 26 ◽  
pp. 32 ◽  
Author(s):  
Zhana Petkova ◽  
Ginka Antova
Keyword(s):  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Thermal Treatment ◽  
Microwave Heating ◽  
Acid Composition ◽  
Seed Oil ◽  
Conventional Heating ◽  
Melon Seed ◽  
Sunflower Oils ◽  
Melon Seed Oil

Current paper reveals the impact of thermal treatment on the quality of two seed oils – pumpkin and melon compared to the quality of the most used oil – sunflower oil. Conventional and microwave heating were used for processing the oils. The duration of the thermal treatment was 9, 12 and 18 min for the conventional heating. The microwave heating was performed with two microwave powers of the equipment (600 W and 900 W) for 3, 6, 9 and 12 min. At every stage of the thermal processing were determined acid and peroxide value, the absorbance of the oils at 232 and 268 nm, tocopherol and fatty acid composition. It was observed that the degree of oxidation of the examined oils during microwave and conventional heating increased with the duration of the thermal process and the power of the microwaves. Also, the two methods of heating had a little impact on the processes leading to the formation of free fatty acids. Total tocopherols of the melon seed oil were more stable to thermal treatment. The amount of linoleic acid decreased in the pumpkin and sunflower oils during microwave treatment, while that of oleic and palmitic acid relatively increased. The biggest change in the fatty acid composition of both oils was found during microwave heating at 900W. The changes in fatty acid composition of thermally treated melon seed oil were insignificant. Overall, melon seed oil was observed to be more thermally stable than pumpkin and sunflower oils.

Comparative study of conventional and microwave heating of polyacrylonitrile-based fibres

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Guozhen Zhao ◽  
Jianhua Liu ◽  
Lei Xu ◽  
Shenghui Guo
Keyword(s):  
Microwave Heating ◽  
Surface Defects ◽  
Energy Dispersive Spectrometer ◽  
Xrd Analysis ◽  
Economic Benefits ◽  
Heating Time ◽  
Oxidation Temperature ◽  
Conventional Heating ◽  
Heating Method ◽  
Molecular Arrangement

Abstract The effects of the conventional heating method and the microwave heating method on polyacrylonitrile-based fibres in the temperature range of 180–280 °C were investigated. Fourier transform infrared spectroscopy, X-ray wide-angle scattering, Raman spectroscopy, energy-dispersive spectrometer, scanning electron microscopy and bulk density were used to characterise the properties of the samples. Results show that the microwave heating method can shorten the pre-oxidation time, reduce pre-oxidation temperature and reduce the number of surface defects. The pre-oxidised fibres obtained by the microwave heating method exhibit not only good crystallite size but also a smooth surface. Atomic morphology and molecular arrangement are orderly inside the fibre. The FT-IR spectrum shows that the oxidation reaction occurs at 220 °C, and the CI value of PAN fibers stabilised by microwave heating is the larger than the fibers stabilised by conventional heating. XRD analysis shows that fibers stabilised by microwave heating have low stack domains. The SEM and Raman spectra indicate that hydrogen peroxide can improve the surface finish of the fibers and reduce defects. Microwave heating can reduce the pre-oxidation temperature by about 20 °C and shorten the heating time. The economic benefits of using this method are significantly improved.

Preparation of WC-TiC-Ni3Al-CaF2 functionally graded self-lubricating tool material by microwave sintering and its cutting performance

2020 ◽  
Vol 39 (1) ◽  
pp. 45-53 ◽  
Author(s):  
Siwen Tang ◽  
Rui Wang ◽  
Pengfei Liu ◽  
Qiulin Niu ◽  
Guoqing Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Microwave Heating ◽  
Cutting Performance ◽  
Conventional Heating ◽  
Hard Alloys ◽  
Dry Cutting ◽  
Temperature Oxidation ◽  
Lubricating Material ◽  
Heating Technology

AbstractWith the concern of the environment, green dry cutting technology is getting more and more attention and self-lubricating tool technology plays an important role in dry cutting. Due to the demand for high temperature performance of tools during dry cutting process, cemented carbide with Ni3Al as the binder phase has received extensive attention due to its excellent high temperature strength and high temperature oxidation resistance. In this paper, WC-TiC-Ni3Al-CaF2 graded self-lubricating material and tools were prepared by microwave heating method, and its microstructure, mechanical properties and cutting performance were studied. Results show that gradient self-lubricating material can be quickly prepared by microwave heating technology, and the strength is equivalent to that of conventional heating technology. CaF2 not only plays a role in self-lubrication, but also refines the grain of the material. A reasonable gradient design can improve the mechanical properties of the material. When the gradient distribution exponent is n1 = 2, the material has high mechanical properties. Cutting experiments show that the WC-TiC-Ni3Al-CaF2 functional gradient self-lubricating tool has better cutting performance than the homogeneous WC-TiC-Ni3Al hard alloys.

Volcanic Glass as a Natural Analog for Borosilicate Waste Glass

1993 ◽  
Vol 333 ◽  
Author(s):  
Maury E. Morgenstein ◽  
Don L. Shettel
Keyword(s):  
Silica Glass ◽  
Glass Structure ◽  
Volcanic Glass ◽  
Waste Glass ◽  
Tensile Failure ◽  
Tensile Fracture ◽  
Failure Behavior ◽  
Basaltic Glass ◽  
Glass Waste ◽  
Natural Analog

ABSTRACTObsidian and basaltic glass are opposite end-members of natural volcanic glass compositions. Syngenetic and diagenetic tensile failure in basaltic glass (low silica glass) is pervasive and provides abundant alteration fronts deep into the glass structure. Perlitic fracturing in obsidian (high silica glass) limits the alteration zones to an “onion skin” geometry. Borosilicate waste glass behaves similarly to the natural analog of basaltic glass (sideromelane).During geologic time, established and tensile fracture networks form glass cells (a three-dimensional reticulated pattern) where the production of new fracture surfaces increases through time by geometric progression. This suggests that borosilicate glass monoliths will eventually become rubble. Rates of reaction appear to double for every 12C° of temperature increase. Published leach rates suggest that the entire inventory of certain radionuclides may be released during the 10,000 year regulatory time period. Steam alteration prior to liquid attack combined with pervasive deep tensile failure behavior may suggest that the glass waste form is not license defensible without a metallic- and/or ceramic-type composite barrier as an overpack.

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