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Secion 5. Physicsy
https://doi.org/10.29013/ESR-22-1.2-26-30
Arziqulov Eshquvat Ulashevich, Doctor of Physical and Mathematical Sciences, Samarkand State University, Samarkand, Uzbekistan
E-mail: eshkuvata@gmail.com Eshmamatov Sardor Quchqor ugli, PhD Student, Samarkand State University, Samarkand, Uzbekistan E-mail: sardor.eshmamatov@mail.ru
SURFACE MORPHOLOGY OF STEEL SYNTHESIZED BY MELTING A FLAME SUPERSONIC JET OF MIXTURE PROPANE AND AIR GASES
Abstract. Currently, one of the most important problems in solid state physics and materials science is the development of new materials used in various fields of human activity, as well as the improvement of the properties of existing ones. In recent years, the use of composite and porous structural materials in the field of materials science has been expanding [1; 2]. This article describes the results of research on the surface morphology of porous samples, which were synthesized by melting a sample of industrial steel «Stal-3» at different temperatures in the flame of a supersonic jet of air-propane gases using a special nozzle that generates supersonic jet.
Keywords: Porous steel, porous structure, morphology, porosity, element analysis.
1. Introduction supersonic flame of a mixture of air-propane gases
The electrophysical, magnetic, thermal, optical, at high temperatures using a special nozzle [4].
galvanomagnetic, and magnetotransport properties Experiments have shown that the sample surface
of porous structural materials differ from those of (volume) consists of open and closed elemental
conventional materials due to the size of the pores, spherical cells with an average diameter of 350 nm
the degree of porosity, and the distribution of the to 200 ^m, which are arranged randomly.
pores. Although the electrophysical, mechanical, 2. Experiment
thermal, and other properties of porous materials Surface morphology and element analysis of
have been extensively studied, there is no single porous steel samples synthesized in the superson-
theory that perfectly describes all of their proper- ic flame of the first metallic steel and propane-air
ties [3]. This work presents the results of experi- gases were carried out using a scanning electron
ments using modern electron microscopic methods microscope EVO LS15 "Carl Zeiss Microscopy
on the surface of porous steel samples synthesized Ltd". This electron microscope object can enlarge
in the temperature range 1500 ^ 1800 °C in the micro-images from 5 up to 1000000 times [5]. The
micrographs of the surface morphology of the ini- tial sample and the porous steel sample are shown
in (Figure 1) below.
a) b)
Figure 1. Micrographs of the surface topology obtained using a scanning electron microscope: a) a sample of the original steel; b) micrometer-sized pores
As can be seen from the figure, the surface of the first steel sample has the appearance of a polycrys-talline solid. The pores on the surface look similar in shape, but they differ in size. The porous structural surface of the samples was observed from mm to nanometers and evaluated by the size of the open pores on the surface.
In addition to the scanning electron microscope, the study of nano-sized structures present on the surface of porous steel samples was performed using a Core AFM 300 atomic force microscope. The Core AFM 300 Atomic Power Microscope Conti-lever (needle) allows 2D and 3D micro-images of the surface's atomic-level virtual relief by interacting with atoms on the surface of the sample. The base of the sample is controlled by a piezoelectric axis along the XYZ axes, and the maximum range of motion along the axes is 100 ^m x 100 ^m x 12 ^m. During the experiment, the container is placed on the sample surface with an automated landing speed of 0.01 mm/s [6].
3. Experimental results and discussion
Initially, steel samples of different porosity grades were synthesized as a result of complete melting of an industrial steel sample of Steel-3 type
in the temperature range 1500 ^ 1800 °C in the flame of air-methane mixture (Stal-3 (C-3)). This method can be used to control the degree of porosity and size of samples synthesized in the laboratory by changing the synthesis temperature and pressure ratios of the gas mixture. Knowing the geometric dimensions of the sample, its density was measured using the hydrostatic gravity method to determine the density of solids. Based on the results of the experiment, it was determined that the average density of porous steel samples is pg,=2200 ^ ^ 2500 kg/m3 In comparison, the density of porous steel is 3 to 3.5 times smaller than that of steel. During the analysis of the micro-images obtained in the experiments, it was found that the pores on the surface of the porous steel sample are irregularly arranged, with an open and closed spherical shape [7]. It was also found that their average diameters ranged from 350 nm to 200 ^m, and that the number of pores was approximately equal to Gauss's distribution law. Studying the distribution of the surface of the samples in different samples and in depth allows us to assume that the results obtained on the surface are also valid in terms of approximate size.
a) b)
Figure 2. a) surface micro-image of a porous steel sample; b) the distribution of pores on the surface of 0.30 cm2
The histogram shown in (Figure 2 b) examined the dependence of the number of pores on the surface of a sample with a surface area of 0.30 cm2 on their size, and found that they obeyed Gauss's law of distribution and that the number ofpores ranged from 0 ^ 100 ^m.
In the experiment, surface micro-images of porous steel samples formed after melting of C-3 industrial steel in the flame of unmelted and gaseous mixture in a supersonic jet and the analysis of the element obtained on the surface are shown in (Figure 3) below.
a)
b)
| Cneop 3
Bec.% CT
Fe 95.2 0.5
O 2.6 0.4
Cr 1.0 0.2
fll 0.5 0.2
SI OA 0.1
Mg 0.2 0.2
o I I I I I I I I I I | I I I I I I I I I | I I I I I I I I I | I I I I I I I I
0 5 10 15
H CneKrp4
Bec.% o
Fe 70.4 0.3
0 23.7 0.3
Cr 4.5 02
Ca 0.6 0.1
fll 0.3 0.1
Si 0.3 0.1
CI 0.2 0.1
I i I i I i I i I i I i I i I i I
10 15
i I i I i I i I i
Figure 3. Before melting of C-3 industrial steel: a) and; b) surface microimages and the results of the analysis of the element obtained on the surface after melting the mixture of gases in the flame of a supersonic jet
The results of the test showed that the content of the original C-3 steel alloy sample was 95.2% - Fe, 2.6% - O, 1.0% - Cr, 0.5% - Al, 0.4% - Si and 0.2% -Mg, and the composition of the synthesized porous steel sample was 70,4% ni Fe, 23.7% - O, 4.5% - Cr, 0.6% - Ca, 0.3% - Al, 0.3% - Si and 0.2% Cl. These results showed that the amount of Fe and O atoms in the synthesis process changed significantly. In our view, such changes are caused by the fusion of oxygen atoms in the flame with iron atoms. In other words, the supersonic jet created by the flame when
steel melts causes liquid steel and gas mixtures to
mix, resulting in the formation of various com-
a)
Figure 4. Image of the surface of the
The dimensions of these roughnesses, the surface and depth distributions of the dimensions, showed that the results obtained using an electron microscope scanning the surface morphology of the samples were completely consistent.
4. Conclusion
Based on the analysis of the results of the study, the following conclusions can be drawn:
During the synthesis process, it was found that the number ofpores on the surface of several samples depends on their size, that they obey Gauss's law of
pounds of relatively active oxygen atoms with iron atoms. Changes in the quantities of other elements can be caused by relatively emission light atoms of the sample when the high-speed flame of the supersonic jet is ignited.
A CoreAFM 300 AKM device was used to study the surface relief of the synthesized porous steel sample. The microrelief of the sample surface was obtained using the static force mode of the microscope (Figure 4). The image shows the release of a naturally occurring portion of the sample surface, with the surface of the synthesized specimen consisting of micro- and macroscopic roughnesses.
b)
sample taken on a CoreAFM AFM
distribution, and that the size of a large number of pores ranges from 0 to 100 microns;
As the proportions of iron and oxygen atoms in the synthesized porous steel sample change significantly, such changes are caused by the fusion of the oxygen atoms in the flame with the iron atoms;
In other words, the supersonic jet is created by the flame when steel melts causes liquid steel and gas mixtures to mix, resulting in the formation of various compounds of relatively active oxygen atoms with iron atoms. Changes in the quantities of other
elements may be caused by the release of relatively emission of light atoms of the sample during the high-temperature flame of the supersonic jet;
The results obtained in the AFM showed that the surface of the synthesized sample consisted of micro-
and macroscopic roughnesses, and that the size of these roughnesses, surface and depth distributions, corresponded exactly to the results obtained using an electron microscope scanning the surface morphology of the samples.
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