Researches about the Determination of the Thermal Conductivity Coefficient for Silica Sand Moulds Used in Romanian Foundries

2010 ◽  
Vol 457 ◽  
pp. 312-317 ◽  
Author(s):  
Ioan Ciobanu ◽  
Mihai Chisamera ◽  
Sorin Ion Munteanu ◽  
Aurel Crişan ◽  
Iulian Riposan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Cast Iron ◽  
Thermal Conductivity Coefficient ◽  
Thermal Analyses ◽  
Transport Processes ◽  
Solidification Time ◽  
Silica Sand ◽  
Water Evaporation ◽  
Mould Wall

The paper presents the results of the researches regarding the determination of the thermal conductivity coefficient of the moulds used for cast iron parts in Romanian foundries. The instantaneous values of the thermal conductivity coefficient of the moulds are influenced by the type of materials that compose the moulding batch (sand, binder, additional materials) their content (percentage) their characteristics (grains form and dimensions), but also by the temperature. Many software used for casting solidification uses a mean substitutive value. This one include the effect of heat transmission by conduction in the mould wall and the secondary processes that influence the heat transfer throw the mould wall ( burning processes of organic substances, water evaporation and re-condensation processes, mass transport processes). The determination of this mean value in the case of casting grey cast iron parts with thickness of 20 mm is presented in the paper. A regressive method was applied. The solidification time experimentally determined throw thermal analyses is compared with the solidification time obtained by simulation, in three points of the casting. The value of the substitutive coefficient of thermal conductivity that assure the best closeness between the simulated solidification time and the solidification time experimentally determined throw thermal analysis in the three points was established.

scholarly journals Opening Material as the Possibility of Elimination Veining in Foundries

2016 ◽  
Vol 16 (3) ◽  
pp. 157-161 ◽  
Author(s):  
M. Hrubovčáková ◽  
I. Vasková ◽  
M. Benková ◽  
M. Conev
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Thermal Expansion ◽  
Cast Iron ◽  
Granular Material ◽  
Surface Defects ◽  
Silica Sand ◽  
Iron Castings ◽  
Thermal Dilatation

Abstract The main bulk density representation in the molding material is opening material, refractory granular material with a particle size of 0.02 mm. It forms a shell molds and cores, and therefore in addition to activating the surface of the grain is one of the most important features angularity and particle size of grains. These last two features specify the porosity and therefore the permeability of the mixture, and thermal dilatation of tension from braking dilation, the thermal conductivity of the mixture and even largely affect the strength of molds and cores, and thus the surface quality of castings. [1] Today foundries, which use the cast iron for produce of casts, are struggling with surface defects on the casts. One of these defects are veining. They can be eliminated in several ways. Veining are foundry defects, which arise as a result of tensions generated at the interface of the mold and metal. This tension also arises due to abrupt thermal expansion of silica sand and is therefore in the development of veining on the surface of casts deal primarily influences and characteristics of the filler material – opening material in the production of iron castings.

scholarly journals Analysis of Specificity of ecological insulation material thermal Parameters

2018 ◽  
Vol 251 ◽  
pp. 01011 ◽  
Author(s):  
Baiba Gaujena ◽  
Jelena Tihana ◽  
Anatolijs Borodinecs ◽  
Vladislavs Agapovs
Keyword(s):  
Thermal Conductivity ◽  
Water Absorption ◽  
Thermal Conductivity Coefficient ◽  
Insulation Material ◽  
Drying Process ◽  
Hemp Fiber ◽  
Characteristics Method ◽  
Quality Water ◽  
Absorption Thickness

This paper is devoted to analysis of insulation materials quality and characteristics, method for the determination of thermal conductivity coefficient and the influence of various factors on the thermal conductivity coefficient. The paper summarizes the estimated process consumption of thermal energy. The research is defined experimental hemp fiber-sheaves insulation plates manufactured in Latvia further specified actual parameter and quality water absorption; thickness changes; drying process; thermal conductivity coefficient; thermal conductivity coefficient depending from moisture. Research is made using experimental hemp fiber-sheaves insulation pattern manufactured in Latvia – plates in size 300 x 300 mm. In research totally are used three hemp fiber-sheaves pattern series with different substance and extrusion modes. Each series consist from four plate with different thickness. As result of research is determined hemp fiber-sheaves insulation pattern Water absorption, dynamics of Drying process, Thickness changes, Thermal conductivity coefficient and Thermal conductivity coefficient depending from moisture.

scholarly journals Thermal Conducting Properties of Metal-fluoroplastic Material Determined by Tribological Method

2021 ◽  
pp. 378-384
Author(s):  
Vasily N. Kornopoltsev ◽  
Bair B. Damdinov
Keyword(s):  
Thermal Conductivity ◽  
Sheet Metal ◽  
Thermal Conductivity Coefficient ◽  
Steel Substrate ◽  
Approximate Determination ◽  
Fourier Law ◽  
Thermophysical Characteristics ◽  
Friction Zone ◽  
Thermal Conducting

The work is devoted to considering the possibility of using the Fourier law and the data of tribological tests for the approximate determination of the thermophysical characteristics of the sheet metal-fluoroplastic material on a steel substrate. The thermal conductivity coefficient of two different fluoroplastic materials was determined by tribological method using the temperature difference in the friction zone. It was shown that friction conditions change from viscoelastic to plastic

A Simple Method for Determination of Thermal Conductivity Coefficients of Thin Films

2001 ◽  
Author(s):  
Chi Hsiang Pan ◽  
Chien Li Tung
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Thermal Conductivity Coefficient ◽  
Crystalline Silicon ◽  
Silicon Film ◽  
Simple Method ◽  
Active Devices ◽  
Analytical Expressions

Abstract In this paper, we present a simple method to determine thermal conductivity coefficients (TCC) of thin films with a compact characterization microstructure and by using common measuring apparatus. The microstructure can be fabricated by a simple surface micromachining technique and in situ along with active devices on the same chip. Analytical expressions are derived to calculate the thermal conductivity coefficients of thin films from the experimental data. Experimental results with a heavily n-doped LPCVD poly crystalline silicon film are used herein to demonstrate the effectiveness of the proposed method. The obtained thermal conductivity coefficient seems to decrease a little as temperature increase and the average is around 39 Wm−1 °C−1 at 400°C below.

The Estimation of the Thermal Properties of Refractory Materials According to the Temperatures Acceleration Curve at the Blast Furnace Blowing-In

2015 ◽  
Vol 1095 ◽  
pp. 476-482 ◽  
Author(s):  
A.N. Dmitriev ◽  
Maxim O. Zolotykh ◽  
Yury A. Chesnokov ◽  
Oleg Yu. Ivanov ◽  
Galina Yu. Vitkina
Keyword(s):  
Thermal Conductivity ◽  
Mathematical Model ◽  
Blast Furnace ◽  
Thermal Properties ◽  
Thermal Conductivity Coefficient ◽  
Refractory Materials ◽  
Different Types ◽  
Definition Of ◽  
The Mathematical Model

In a laying of a hearth it is usually used to ten different types of the flameproof materials. The characteristics of materials declared by the manufacturer can differ from the actual. For creation of the mathematical model [1, 2] temperatures distributions in a laying of the concrete furnace it is necessary to know thermal conductivity of materials of the specific parties used at construction of the furnace. Definition of the thermal conductivity coefficient allows adapt mathematical model for specific conditions of use. The technique of determination of thermal properties of refractory materials on the temperatures acceleration curve at blowing-in of the blast furnace is described.

Effect of Colloidal Silicon Dioxide on the Properties of Building Ceramics

2020 ◽  
Vol 992 ◽  
pp. 173-177
Author(s):  
S.V. Vasyunina ◽  
N.P. Lukuttsova ◽  
V.O. Momot
Keyword(s):  
Thermal Conductivity ◽  
Silicon Dioxide ◽  
Thermophysical Properties ◽  
Thermal Conductivity Coefficient ◽  
Average Density ◽  
Silica Sand ◽  
Optimal Amount ◽  
Engineering Environment ◽  
Better Than

The paper presents the results of the researches on improving the physical-mechanical and thermophysical properties (average density, strength and thermal conductivity) of ceramic stone with colloidal silicon dioxide, with and without the mineral thinning additive of silica sand. In the course of the study, the most optimal amount of colloidal silicon dioxide for ceramic stone samples is determined. The dependence of strength, average density and thermal conductivity coefficient on the amount of the modifier and thinner is established. The graphic dependences are constructed by the method of extreme modelling on the basis of Scilab engineering environment. It is ascertained that the application of colloidal silicon dioxide can improve the physical-mechanical and thermophysical properties of ceramic stone. The results of the studies on ceramic stone modified with silica sand and colloidal silicon dioxide were better than without the sand supplement. The optimal amount of colloidal silicon dioxide in the composition of ceramic stone without a sand thinning additive is 0.2%, and 0.3% with this supplement.

scholarly journals Direct stochastic molecular modelling of transport processes in gases

2021 ◽  
Vol 2056 (1) ◽  
pp. 012003
Author(s):  
V Ya Rudyak ◽  
E V Lezhnev
Keyword(s):  
Thermal Conductivity ◽  
Diffuse Reflection ◽  
Thermal Conductivity Coefficient ◽  
Rarefied Gas ◽  
Transport Coefficients ◽  
High Accuracy ◽  
Transport Processes ◽  
Modeling Transport ◽  
Gas Molecules ◽  
First Time

Abstract The stochastic molecular modeling method (SMM) of transport processes in rarefied gases developed by the authors is systematically discussed in this paper. It is shown that, it is possible to simulate the transport coefficients of rarefied gas with high accuracy, using a relatively small number of molecules. The data of modeling the thermal conductivity coefficient are presented for the first time. The second part of the paper is devoted to the generalization of the SMM method for modeling transport processes in confined conditions. To describe the dynamics of molecules in this case, the splitting of their evolution by processes is used: first, the movement of molecules in the configuration space is simulated, and then their dynamics in the velocity space is imitated. Anisotropy of viscosity and thermal conductivity in nanochannels has been established. The interaction of gas molecules with walls is described by specular or specular-diffuse reflection laws. Gas viscosity can be either greater than in the bulk or less, depending on the law of gas interaction with the channel walls.

Determination of the thermal conductivity coefficient of inhomogeneous media

2014 ◽  
Author(s):  
S. A. Bochkareva ◽  
N. Yu. Grishaeva ◽  
P. A. Lyukshin ◽  
B. A. Lyukshin
Keyword(s):  
Thermal Conductivity ◽  
Thermal Conductivity Coefficient ◽  
Inhomogeneous Media
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