scholarly journals Kinetics of Hardening and Drying of Ceramic Moulds with the New Generation Binder – Colloidal Silica

2013 ◽  
Vol 13 (4) ◽  
pp. 112-116
Author(s):  
J. Zych ◽  
J. Kolczyk
Keyword(s):  
Grain Size ◽  
Significant Influence ◽  
Colloidal Silica ◽  
Gravimetric Method ◽  
Drying Time ◽  
Casting Technology ◽  
Successive Layer ◽  
Drying Rates ◽  
New Generation ◽  
Kinetics Of

Abstract The influence of selected factors on drying ceramic moulds applied in the investment casting technology was determined by the gravimetric method. Moulds produced of ceramic sands based on the new generation binders - colloidal silica, were investigated. It was found that each successive layer, of a similar thickness, is drying longer than the previous one. The drying time of layers forming closed spaces is several times longer as compared with drying open surfaces (external). Grain size of matrix used for moulds sprinkling has none significant influence on drying rates.

scholarly journals The Influence of Benzoyl Peroxide on Gelation Rate of Silica Binder for Precision Casting

2013 ◽  
Vol 13 (2) ◽  
pp. 99-102
Author(s):  
M. Nadolski ◽  
Z. Konopka ◽  
M. Łągiewka ◽  
A. Zyska
Keyword(s):  
Benzoyl Peroxide ◽  
Colloidal Silica ◽  
Single Layer ◽  
Production Cycle ◽  
Drying Process ◽  
Precision Casting ◽  
Casting Technology ◽  
Shell Mould ◽  
Kinetics Of ◽  
Moulding Material

Abstract Substituting of ethyl silicate with ecologic sols of colloidal silica in the investment casting technology, resulting from the increased demands concerning environmental protection, caused the prolongation of production cycle for precision castings produced in multi-layer thin-walled ceramic shell moulds. Modification of Sizol 030 binder with benzoyl peroxide, proposed in the paper, was aimed at restriction of time needed for realization of a single layer of the shell mould, and by the same, of such a mould as a whole. Examination of kinetics of the drying process were held for the layers made of prepared moulding material and the influence of binder modification on the mould curing time was determined.

scholarly journals Effect of pre-treatments on solar drying kinetics of red seedless grapes (cv. Monukka)

2014 ◽  
Vol 3 (2) ◽  
Author(s):  
Inês Nunes Ramos ◽  
Teresa R.S. Brandão ◽  
Cristina L.M. Silva
Keyword(s):  
Edible Oil ◽  
Hot Water ◽  
Drying Time ◽  
Water Emulsion ◽  
Oil Emulsion ◽  
Oil Water ◽  
Drying Rates ◽  
Drying Curves ◽  
Kinetics Of ◽  
Best Fit

Two different pre-treatments were applied to grapes prior to drying in a mixed mode solar dryer. Grapes were blanched in water and in a 0.1% sunflower oil water emulsion, both at 99oC and for approximately 15 seconds. Several models were tested to fit the experimental data of drying curves but the normalized Newton model gave the best fit results. Samples blanched in hot water or in the 0.1% edible oil emulsion had faster drying rates than untreated samples. Contrary to what was expected, pre-treating with the 0.1% edible oil emulsion did not increase the drying rate to a higher extent than blanching. Pre-treatments did not give a noteworthy difference in the total drying time. However, they had an important role in accelerating initial drying rates, thus preventing moulds and bacterial growth and consequently increasing farmers’ income.

scholarly journals Influence of the Al2O3 Solid Phase on the Kinetics of Binding Ceramic Moulds

2017 ◽  
Vol 17 (4) ◽  
pp. 91-96
Author(s):  
J. Kolczyk ◽  
J. Zych ◽  
Ł. Jamrozowicz
Keyword(s):  
Solid Phase ◽  
Ultrasonic Method ◽  
Drying Time ◽  
Casting Technology ◽  
Ceramic Slurry ◽  
Solid Phase Content ◽  
Binding Agents ◽  
Multilayer Ceramic ◽  
Kinetics Of ◽  
Slurry Viscosity

Abstract The investigation results of the kinetics of binding ceramic moulds, in dependence on the solid phase content in the liquid ceramic slurries being 67, 68 and 69% - respectively, made on the basis of the aqueous binding agents Ludox AM and SK. The ultrasonic method was used for assessing the kinetics of strengthening of the multilayer ceramic mould. Due to this method, it is possible to determine the ceramic mould strength at individual stages of its production. Currently self-supporting moulds, which must have the relevant strength during pouring with liquid metal, are mainly produced. A few various factors influence this mould strength. One of them is the ceramic slurry viscosity, which influences a thickness of individual layers deposited on the wax model in the investment casting technology. Depositing of layers causes increasing the total mould thickness. Therefore, it is important to determine the drying time of each deposited layer in order to prevent the mould cracking due to insufficient drying of layers and thus the weakening of the multilayer mould structure.

scholarly journals Microwave Drying of Banana (Musa acuminata) Stalk Biomass before Conversion to Value-added Products

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
O. O. Agbede
Keyword(s):  
Activation Energy ◽  
Value Added ◽  
Microwave Drying ◽  
Waste Biomass ◽  
Drying Time ◽  
Effective Moisture ◽  
Thin Layer Drying ◽  
Drying Rates ◽  
Kinetics Of ◽  
Value Added Products

Banana stalk biomass can pose disposal, environmental and health challenges. Fortunately, this biomass can be converted to value-added products including biofuels, bioenergy, biosorbents, fibers and animal feeds. However, it is necessary to remove moisture from the fresh biomass by drying before storage and conversion processes. Conventional drying in open sun is slow and weather dependent, but higher heating rates and faster drying rates can be achieved in a microwave dryer. Hence, the microwave drying characteristic of banana stalk biomass was investigated. Banana stalks were sliced into 5 mm thick pieces and dried in a microwave oven at power levels of 400 – 1000 W, the stalk slices were weighed at interval until the mass remained constant. The effective moisture diffusivity, activation energy and energy required for drying were determined. The microwave drying data were also fitted to twelve thin layer drying mathematical models to describe the kinetics of the drying process. The drying time of banana stalk slices decreased with increasing microwave power. The drying occurred mainly in the falling rate period. The effective moisture diffusivities were 4.14 × 10-9 – 2.00 × 10-8 m2 s-1 at 400 – 1000 W. The activation energy was 122 W g-1 while the total and specific energies required for the microwave drying were 0.25 – 0.37 kWh and 34.8 – 51 kWh/kg, respectively. The Weibull model suitably described the microwave drying kinetics of banana stalk slices. The moisture present in fresh banana stalk waste biomass can be effectively and rapidly removed by microwave drying before conversion processes.

scholarly journals The effect of ohmic heating pretreatment on drying of apple

2018 ◽  
Author(s):  
Aslı Isci ◽  
Naciye Kutlu ◽  
Merve Silanur Yilmaz ◽  
Hicran Arslan ◽  
Ozge Sakiyan
Keyword(s):  
Thin Layer ◽  
Ohmic Heating ◽  
Order Kinetic ◽  
Drying Time ◽  
Thin Layer Drying ◽  
Drying Kinetic ◽  
Apple Slices ◽  
Order Kinetic Model ◽  
Drying Rates ◽  
Kinetics Of

In this study, effects of ohmic pretreatment on the drying rates and color kinetics of apple were investigated. Apple slices were treated at different electric field strengths (20-30 and 40 V/cm) at 60°C for 1 min. Drying process was applied at 60˚C-2 m/s by using a tray-dryer. ΔE and moisture content were calculated. These values were fitted to the semi-theoretical thin-layer drying and the zero and first-order kinetic model. The shortest drying time was found samples treated with 30 V/cm. Wang&Singh model gave the superior fit to the experimental data. ΔE fitted well to the zero-order kinetic model.Keywords: Ohmic heating, drying, kinetic models, thin-layer models, apple.  

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

Study of color kinetics of banana (Musa cavendish) under microwave drying by application of image analysis

2020 ◽  
pp. 108201322098133
Author(s):  
Sagar Nagvanshi ◽  
Subbarao Kotra Venkata ◽  
TK Goswami
Keyword(s):  
Microwave Power ◽  
Vision System ◽  
Power Level ◽  
Microwave Drying ◽  
Slice Thickness ◽  
Order Kinetic ◽  
Drying Time ◽  
Volumetric Heating ◽  
Kinetics Of ◽  
Microwave Power Level

Microwave drying works on the volumetric heating concept promoted by electromagnetic radiation at 0.915 or 2.450 GHz. In this study, banana ( Musa Cavendish) was taken as the sample and treated under microwave drying. The effect of two process variables, namely slice thickness (2, 3.5, and 5 mm) and microwave power (180 W, 360 W, and 540 W), were studied on drying kinetics and color kinetics. It was observed that the inverse variation relationship exists between drying time and microwave power level while drying time and slice thickness exhibited a direct variation relationship. A Computer Vision System (CVS) was developed to measure the color values of banana in CIELab space using an algorithm written in MATLAB software. Once the color parameters were obtained, they were fitted in First and Zero-order kinetic models. Both models were found to describe the color values adequately. This study concludes that microwave drying is a promising dehydration technique for banana drying that reduces the significant time of drying. Application of CVS is an excellent approach to measure the surface color of banana.

Elastic Modulus of Pb/Sn Solder Joints in Microelectronics

2002 ◽  
Author(s):  
Cemal Basaran ◽  
Jianbin Jiang
Keyword(s):  
Grain Size ◽  
Elastic Modulus ◽  
Single Crystal ◽  
Solder Alloy ◽  
Ultrasonic Testing ◽  
Heterogeneous Materials ◽  
Testing Methods ◽  
Nano Indentation ◽  
Deformation Kinetics ◽  
Kinetics Of

Young’s modulus (E) values published in literature for the eutectic Pb37/Sn63 and near eutectic Pb40/Sn60 solder alloy vary significantly. One reason for this discrepancy is different testing methods for highly rate sensitive heterogeneous materials, like Pb/Sn alloys, yield different results. In this paper, we study different procedures used to obtain the elastic modulus; analytically, by single crystal elasticity and experimentally by ultrasonic testing and Nano indentation. We compare these procedures and propose a procedure for elastic modulus determination. The deformation kinetics of the Pb/Sn solder alloys is discussed at the grain size level.

STUDY OF THE KINETICS OF DRYING BREWER’S SPENT GRAIN

2020 ◽  
Author(s):  
Т.Г. КОРОТКОВА ◽  
А.С. ДАНИЛЬЧЕНКО ◽  
Н.Ю. ИСТОШИНА
Keyword(s):  
Matter Content ◽  
Dry Matter Content ◽  
Drying Time ◽  
Brewer’S Spent Grain ◽  
Average Value ◽  
Free Moisture ◽  
Before And After ◽  
Spent Grain ◽  
Kinetics Of ◽  
Two Temperature

Исследована кинетика сушки сырой пивной дробины – вторичного продукта ООО «Белореченский пивоваренный завод» (Россия, Краснодарский край). Сушка проведена в двух температурных режимах – 60 и 55°С. Скорость сушильного агента при вынужденной конвекции составляла 4,5 м/с. Содержание сухого вещества определено по ГОСТ 31640–2012 в лабораторных условиях и составило 12,9%. Измерение убыли массы при сушке проведено с интервалом 5 мин. Общее время сушки навески пивной дробины в количестве 50 г – 420 мин при режиме 50°С, 360 мин – при 60°С. Среднее значение конечной влажности пивной дробины составило 11,85%. Построены кривые сушки и скорости сушки. Скорость сушки при удалении свободной влаги в первом периоде сушки, мин–1: при 60°С – 3,5, при 55°С – 3,0. Установлено, что содержание связанной влаги составляет в среднем 57% от массы влаги в навеске пивной дробины, свободной влаги – 43%. Анализ структуры навески пивной дробины под микроскопом до сушки и после нее подтвердил факт, что в исследованном материале количество связанной влаги больше, чем свободной. Наличие частиц размером 5–7 мм свидетельствует о значительном количестве клеточной влаги в неразрушенных капиллярах. Дальнейшее совершенствование технологии переработки пивной дробины должно быть направлено на разрушение клеточной структуры материала после его механического обезвоживания. The kinetics of drying of the crude brewer’s spent grain – a secondary product of LLC «Belorechensky brewery» (Russian Federation, Krasnodarregion) has been studied. Drying is carried out in two temperature modes – 60 and 55°C. The speed of the drying agent under forced convection was 4,5 m/s. The dry matter content was determined according to GOST 31640–2012 in laboratory conditions and was 12,9%. Measurement of mass loss during drying was performed at an interval of 5 min. The total drying time of the brewer’s spent grain sample in the amount of 50 gis 420 min at 50°C, 360 min – at 60°C. The average value of the final moisture content of brewer’s spent grain made up 11,85%. Curves of drying and drying speed are constructed. Drying speed when removing free moisture in the first drying period, min–1: at 60°C – 3,5, at 55°C – 3,0. It was found that the content on average of bound moisture is 57% of the mass of moisture in brewer’s spent grain, free moisture – 43%. Analysis of the structure sample of brewer’s spent grain a microscope before and after drying confirmed the fact that the amount of bound moisture in the studied material is greater than the amount of free moisture. The presence of particles of 5–7 mm in size indicates a significant amount of cellular moisture in undisturbed capillaries. Further improvement of the technology for processing brewer’s spent grain should be aimed at destroying the cellular structure of the material after its mechanical dehydration.

Refinement of Size Distributions for Primary Crystallizations

1997 ◽  
Vol 481 ◽  
Author(s):  
E. Pineda ◽  
T. Pradell ◽  
D. Crespo ◽  
N. Clavaguera ◽  
J. ZHU ◽  
...  
Keyword(s):  
Grain Size ◽  
Metastable Phase ◽  
Primary Crystallization ◽  
Controlled Growth ◽  
Diffusion Controlled ◽  
Average Grain Size ◽  
Soft Impingement ◽  
Single Grain ◽  
Kinetics Of ◽  
And Diffusion

ABSTRACTThe microstructure developed in primary crystallizations is studied under realistic conditions. The primary crystallization of an amorphous alloy is modeled by considering the thermodynamics of a metastable phase transition and the kinetics of nucleation and crystal growth under isothermal annealing. A realistic growth rate, including an interface controlled growth at the beginning of the growth of each single grain and diffusion controlled growth process with soft impingement afterwards is considered. The reduction in the nucleation rate due to the compositional change in the remaining amorphous matrix is also taken into account. The microstructures developed during the transformation are obtained by using the Populational KJMA method, from the above thermodynamic and kinetic factors. Experimental data of transformed fraction, grain density, average grain size, grain size distribution and other related parameters obtained from annealed metallic glasses are modeled.

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