scholarly journals Electrical Properties of Multilayer Systems Composed of Foundry Tooling and Moulding Sand

2017 ◽  
Vol 17 (2) ◽  
pp. 21-24
Author(s):  
B. Gal ◽  
K. Granat
Keyword(s):  
Electrical Properties ◽  
Microwave Heating ◽  
Structural Changes ◽  
Chemical Properties ◽  
Heating Power ◽  
Real Component ◽  
Multilayer Systems ◽  
Empirical Modelling ◽  
Physico Chemical ◽  
Moulding Sand

Abstract Within the research, selected multilayer technological systems created as combinations of water-glass containing moulding sand with foundry tooling, were characterised on the grounds of their electrical properties. By measuring resonance frequency and quality factor of a waveguide resonance cavity, real component of permittivity εr’ and loss tangent tgδ were determined for multilayer foundry systems with various qualitative and quantitative compositions. It was demonstrated that combination of a sandmix and foundry tooling with known dielectric properties results in a system with different physico-chemical properties, whose relation to the parameters of individual components of the system is undefined at this research stage. On the grounds of measurement results, theoretical value of microwave heating power, dissipated in unit volume of the selected multilayer foundry system, was determined. Knowledge of theoretical heating power and evaluation of physical, chemical and structural changes occurring in moulding sands exposed to microwaves in such a technological system makes a ground for empirical modelling of the process of microwave heating of foundry moulds and cores.

Thermal Runaway of the BaCO3 + Fe2O3 Homogenous Mixture and Mechanical Alloys at the Microwave Heating

2013 ◽  
Vol 837 ◽  
pp. 185-189 ◽  
Author(s):  
I. Danut Savu ◽  
Sorin Vasile Savu ◽  
Gabriel Constantin Benga
Keyword(s):  
Electrical Properties ◽  
Heat Source ◽  
Microwave Heating ◽  
Structural Changes ◽  
Critical Phenomenon ◽  
Ceramic Materials ◽  
Heating Time ◽  
Thermal Runaway ◽  
Heating Process ◽  
Active System

Microwave heating represents a modern technique to sintering the composites materials. The microwaves absorbance property of the materials is depending by the electrical permittivity of the materials. Researchers showed that the ceramic materials are suitable for sintering using microwave heating. The most important advantage of that sintering procedure is the reduced sintering time and temperatures. However, during the heating process these properties are changing and a pattern of the heating process cannot be established. The penetration depth of microwaves into materials depends on the electrical properties of them, and gives rise to a heat source. The electromagnetic wave absorption is responsible for the macro and micro structural changes in the materials morphology, and consequently for their electrical properties. Thermal runaway is one phenomenon which should be avoided during the microwave processing of the materials. The microwave heating consists in direct introduction of the energy in the volume of the material. If the absorbance properties of the material are increasing with temperature, than a critical phenomenon, called thermal runaway, appears during the heating process. This paper aims to study the thermal runaway of the BaCO3 + Fe2O3 homogenous mixture and mechanical alloy in a mono-mode applicator, when the heat source is a microwave generator at 2,45 Ghz. A special mono-mode chamber has been designed with dimensions 140 x 140 x 70 mm and an active system for rotating the samples, in order to record the values of the temperature and to assure a uniform exposure of the samples to the high frequency electromagnetic field. The materials used in experiments were homogenous mixture of BaCO3 + Fe2O3 which have been milled in a planetary ball mill for 5 and 20 hours. The experimental procedure consists in establishing the levels of the temperatures during the microwave heating process when the thermal runaway appears. These experiments have been done for fixed levels of microwave injected power from 0 1250 W. Numerical simulation for different heating conditions (microwave power, heating time, position of the samples inside the chamber) has been performed in order to elaborate a predictable mathematical model for continuous microwave heating and avoiding the thermal runaway of the homogenous mixture.

Researches on the Properties of Stearate-Carboxymethyl Konjac Glucomannan Ester Prepared by Microwave Method

2011 ◽  
Vol 295-297 ◽  
pp. 117-125
Author(s):  
Xiao Man Zeng ◽  
Bei Yu Liu ◽  
Jian Wang ◽  
Geng Zhong ◽  
Yu Hong Xia
Keyword(s):  
Ambient Temperature ◽  
Microwave Heating ◽  
Chemical Properties ◽  
Konjac Glucomannan ◽  
Microwave Method ◽  
Physico Chemical ◽  
Substitution Degree ◽  
Oil Water ◽  
Carboxymethyl Konjac Glucomannan ◽  
Thermal Stable

In this study, microwave heating was used for the preparation of stearate-carboxymethyl konjac glucomannan ester (SCMK), which introduced hydrophilic carboxymethyl and hydrophobic stearate groups on konjac glucomannan (KMG) backbone. The physico-chemical properties and structure of SCMK were investigated. Results show that the viscosity of SCMK is much lower than that of KGM, but larger slightly than the carboxymethyl konjac glucomannan (CMK) and the viscosity is still stable after being placed for 48 h at ambient temperature. Its transmittance decreases and the resistance ability of SCMK solution to salt/sugar as well as base have been significantly promoted. Moreover, SCMK with substitution degree (DS) of 0.02 is proved to be a sound oil/water emulsifier which its HLB value is 13.01. In FTIR spectrum, the absorption peak of SCMK decreases at 2161.84 cm-1 and 2360.74 cm-1. Meanwhile, TGA indicates that SCMK is less thermal stable than KGM and CMK, but is still good.

Structural and Functional Properties of Heat-processed Soybean Flour: Effect of Proteolytic Modification

2009 ◽  
Vol 15 (5) ◽  
pp. 453-463 ◽  
Author(s):  
C. Radha ◽  
V. Prakash
Keyword(s):  
Functional Properties ◽  
Structural Changes ◽  
Chemical Properties ◽  
Surface Hydrophobicity ◽  
Soy Flour ◽  
Heat Processing ◽  
Enzymatic Modification ◽  
Defatted Soy Flour ◽  
Physico Chemical ◽  
Structural And Functional Properties

Heat processing of soybeans alters its structural behavior, solubility, and in turn the functional properties. Heat-processed soy flour was prepared by autoclaving the defatted soy flour at 121 °C at 15 psi. The effect of enzymatic modification on the structural changes and functional properties of heat-processed soy flour was investigated. The combination of heat processing and enzymatic modification was carried out in two ways: (1) enzymatic modification followed by autoclaving and (2) autoclaving followed by enzymatic modification. Defatted soy flour (control), autoclaved soy flour, enzyme-modified flour, enzyme-modified and then autoclaved flour, autoclaved and then enzyme-modified flour were analyzed for physico-chemical and functional properties. Molecular weight profile of the protein was altered depending on the nature of treatments. Structural studies showed that enzymatic modification gave a porous type morphology to the particles. Enzymatic modification of autoclaved soy flour increased its surface hydrophobicity to 3136±400 units from 600±100 units of autoclaved soy flour. The results indicated that enzymatic modification of autoclaved soy flour increased its acid solubility (pH 4—4.5) from 17% to 56% over a control value of 24%. The foaming capacity of the enzyme-modified and then autoclaved soy flour was 80% while that of the autoclaved and then enzyme-modified flour was 42%. The soy flour that was autoclaved and then enzyme modified showed better emulsifying properties (174 mL oil/g flour) than the flour that was enzyme-modified and then autoclaved. The modified soy flour based on its functional and physico-chemical properties should find application in many food systems.

scholarly journals The Physico-Chemical Properties and Exploratory Real-Time Cell Analysis of Hydroxyapatite Nanopowders Substituted with Ce, Mg, Sr, and Zn (0.5–5 at.%)

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3808
Author(s):  
Iuliana Maria Chirică ◽  
Ana-Maria Enciu ◽  
Teddy Tite ◽  
Maria Dudău ◽  
Lucian Albulescu ◽  
...  
Keyword(s):  
Real Time ◽  
Bone Repair ◽  
Structural Changes ◽  
Chemical Properties ◽  
Porous Scaffolds ◽  
Therapeutic Effects ◽  
Cell Analysis ◽  
X Ray ◽  
Physico Chemical

Cation-substituted hydroxyapatite (HA), standalone or as a composite (blended with polymers or metals), is currently regarded as a noteworthy candidate material for bone repair/regeneration either in the form of powders, porous scaffolds or coatings for endo-osseous dental and orthopaedic implants. As a response to the numerous contradictions reported in literature, this work presents, in one study, the physico-chemical properties and the cytocompatibility response of single cation-doped (Ce, Mg, Sr or Zn) HA nanopowders in a wide concentration range (0.5–5 at.%). The modification of composition, morphology, and structure was multiparametrically monitored via energy dispersive X-ray, X-ray photoelectron, Fourier-transform infrared and micro-Raman spectroscopy methods, as well as by transmission electron microscopy and X-ray diffraction. From a compositional point of view, Ce and Sr were well-incorporated in HA, while slight and pronounced deviations were observed for Mg and Zn, respectively. The change of the lattice parameters, crystallite size, and substituting cation occupation factors either in the Ca(I) or Ca(II) sites were further determined. Sr produced the most important HA structural changes. The in vitro biological performance was evaluated by the (i) determination of leached therapeutic cations (by inductively coupled plasma mass spectrometry) and (ii) assessment of cell behaviour by both conventional assays (e.g., proliferation—3-(4,5-dimethyl thiazol-2-yl) 5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay; cytotoxicity—lactate dehydrogenase release assay) and, for the first time, real-time cell analysis (RTCA). Three cell lines were employed: fibroblast, osteoblast, and endothelial. When monophasic, the substituted HA supported the cells’ viability and proliferation without signs of toxicity. The RTCA results indicate the excellent adherence of cells. The study strived to offer a perspective on the behaviour of Ce-, Mg-, Sr-, or Zn-substituted HAs and to deliver a well-encompassing viewpoint on their effects. This can be highly important for the future development of such bioceramics, paving the road toward the identification of candidates with highly promising therapeutic effects.

scholarly journals Effect of Electrical Properties of Materials on Effectiveness of Heating Their Systems in Microwave Field

2014 ◽  
Vol 14 (2) ◽  
pp. 111-114 ◽  
Author(s):  
M. Stachowicz ◽  
B. Opyd ◽  
K. Granat ◽  
K. Markuszewska
Keyword(s):  
Electromagnetic Field ◽  
Electrical Properties ◽  
Loss Factor ◽  
Microwave Field ◽  
Chemical Properties ◽  
Physico Chemical ◽  
Efficiency And Effectiveness ◽  
Properties Of Materials ◽  
Resonance Cavity ◽  
Waveguide Resonance

Abstract In the paper presented are results of a research on influence of electrical and physico-chemical properties of materials being parts of multicomponent and multimaterial systems used in foundry practice on efficiency and effectiveness of microwave heating. Effectiveness of the process was evaluated on the grounds of analysis of interaction between selected parameters of permittivity and loss factor, as well as collective index of energy absorbed, reflected and transmitted by these materials. In the examinations used was a stand of waveguide resonance cavity for determining electrical properties and a stand of microwave slot line for determining balance of microwave power emitted into selected materials. The examinations have brought closer the possibility of forecasting the behaviour of multimaterial systems like e.g. model, moulding sand or moulding box in microwave field on the grounds of various electrical and physico-chemical properties. On the grounds of analysis of the results, possible was selecting a group of materials designed for building foundry instrumentation to be effectively used in electromagnetic field.

scholarly journals Physico-Chemical and Sensory Profiles of Enriched Linz Biscuits

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 771
Author(s):  
Zuzana Hlaváčová ◽  
Eva Ivanišová ◽  
Ľuboš Harangozo ◽  
Ana Petrović ◽  
Denisa Kušteková ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Control Sample ◽  
Chemical Properties ◽  
Matter Content ◽  
Sensory Profile ◽  
Dry Matter Content ◽  
Crude Fibre ◽  
Combustion Heat ◽  
Physico Chemical ◽  
Control Samples

The aim of the present study was to determine the physico-chemical properties (dry matter content, combustion heat, electrical properties, total protein, ash, fat and crude fibre contents, selected amino acids, and trace elements), antioxidant content, and sensory profile of Linz biscuits. They were enriched by the addition of powdered carrot, nettle leaves and elderberry fruit, which is 3% of the product. For comparison of results, a control variant without the addition of these components was also prepared. The enriched biscuits showed slightly higher total ash and crude fibre contents in comparison to the control samples. Results for the antioxidant activity and total polyphenol, flavonoid, and phenolic acid contents of the enriched biscuits were higher in all observed parameters than in the control sample with the best results obtained for Linz biscuits enriched with elderberry and nettle powder. In enriched biscuits, higher contents of iron, zinc, and manganese were measured, especially in biscuits with nettle. Linz biscuits with nettle had higher combustion heat values than control samples; the other two sample types had lower values. We found that the resistance, capacitance, and relative permittivity of the enriched biscuits decreased with frequency according to the power regression function. On the contrary, the conductivity increased with an increasing frequency. Electrical properties were mainly influenced by the water content but also by added components.

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