Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Journal of New Technologies in Environmental Science

2 2017

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Research of influence of the perforation form in metal products on their thermal conductivity

Pavlenko A., Koshlak H., Cheylitko A.

Journal of New Technologies in Environmental Science

2017

Vol. 1, nr 3

108--112

The porosity in metals has been perceived only as a negative factor for a long time, which reduces the mechanical properties and tightness of the material. For preventing and blocking the negative effects of porosity in metals were dedicated a lot of scientific works, some of them are used in present time [1-3]. However, due to numerous experiments the positive factors of porosity in metals were opened. These factors are the combination of physical and mechanical properties such as high stiffness in combination with a very low density (low specific gravity) and/or high gas permeability combined with a high/low thermal conductivity [4]. Thanks to this, porous metals have received a new stage of evolution. Now porosity is being regarded not only as a negative effect of imperfection technology of making metal products, but also as a way to produce a material with unique properties. Globally porous metal materials can be divided into three categories: cellular metals [5]; metallic foams [6] and porous metals [7]. Products from such materials are used in the automotive industry as structural elements; in the aerospace industry as titanium and aluminum sandwich panels; in shipbuilding as a body for passenger vessels; in medicine as implants in humans [8-11]. From the field of use such products must conform to the following parameters: porosity, gas permeability, thermal conductivity, electrical conductivity, density, sound absorption, etc. There are a lot of methods of creation of porous metallic materials today. But complete method of controlling thermal properties of materials by changing parameters of porosity is still no. For creating such method we need to know what factors, under what conditions and with what degree are influence on the required material's parameters. The aim of this work is to investigate the influence of a combination of factors (form, size and position of pores) in the porous metal material on the thermal conductivity.

Dimensions of the nucleus agent pore former closed spherical pores

Pavlenko A., Cheylitko A., Koshlak H., Piotrowski J. Z.

Journal of New Technologies in Environmental Science

2017

Vol. 1, nr 3

101--107

Many experimental data indicate a relationship between the porosity of the material and its thermophysical properties [1-3]. Influence of porosity on the thermal conductivity of the material can be considered following the example of experimental data [2]. The values of thermal conductivity coefficient of iron (58.19 W/(m∙K)) and a rock formation (3.26 W/(m∙K)) differ by almost 18 times, but the filling of iron balls and balls rock formation of the same a porosity of 62.5% has nearly the same coefficient of thermal conductivity (0.0403 W/(m∙K) and 0.0402 W/(m∙K) respectively). However, the way of forming the porous structure has not yet been investigated, and a clear relationship between the porosity and the physical properties of the material not found.