RU2783636C1 - Application of solcoat ceramic coating for diffusive alloying with chrome and silicon of the surface of elements containing iron - Google Patents

Abstract

FIELD: metallurgical industry.

SUBSTANCE: invention relates to the field of obtaining protective metal coatings on steel products, namely to the chemical-thermal treatment of elements of technical structures, which provides diffusion alloying of these structures with chromium and silicon. Application of the Solcoat ceramic coating for simultaneous diffusion alloying with chromium and silicon of the surface of structural steel elements during operation at a temperature not lower than 300°C and not more than 560°C.

EFFECT: provided simplification of diffusion alloying of steel structures with an increase in hardness and wear resistance, and hence durability, including long structures, by providing the possibility of alloying during their operation. In addition, the scope of use of ceramic coatings is expanding.

1 cl, 1 dwg, 1 tbl

Description

Technical field

The invention relates to the field of obtaining protective metal coatings on steel products, namely, to the chemical-thermal treatment of elements of technical structures containing iron, primarily steel structures, which ensures diffusion alloying of these structures with chromium and silicon simultaneously.

State of the art

Diffusion coatings have long been well known.

Diffusion coatings used in antiquity, as a rule, were applied by immersing the product in molten metal, i.e., using the liquid method. However, this relatively simple method could only be used for coating products with fusible metals. Therefore, when the need arose for coatings of refractory metals, in particular with chromium, new methods were developed. With regard to the saturation of the surface layers of alloys with chromium, first of all, the vapor-phase method arose, then the gas and liquid methods.

The physical nature of diffusion alloying of metals is the same regardless of the alloying element.

Diffusion chromium plating is fundamentally different from galvanic chromium plating, in which a layer of chromium is directly applied to the surface of the product. Diffusion chromium plating involves the penetration of chromium into the crystal lattice of the metal by diffusion.

Currently, diffusion chromium plating of alloys is carried out by four methods: solid, vapor-phase, gas and liquid.

The enrichment of the surface layers of the alloy with chromium, which occurs during diffusion chromium plating, is accompanied by significant changes in their structure and physicochemical properties. The surface of the product after diffusion chromium plating acquires very high hardness, wear resistance, heat resistance and corrosion resistance, as well as special magnetic and electrical properties (for example, Dubinin, G.N. Chrome plating of steel. - M .: Metallurgizdat, 1950. - 58 p., [ one]).

The goal of any chemical-thermal process, including diffusion chromium plating and diffusion siliconization, is to impart heterogeneous properties to the working section of the product, especially necessary in cases where the main working functions are the surface zones of the metal.

The purpose of siliconization is to form an acid-resistant surface. In addition, a partial rearrangement of the atomic lattice occurs, due to which the quality of wear resistance increases.

Siliconizing gives steel high corrosion resistance in nitric, sulfuric and hydrochloric acids and slightly increases wear resistance.

Chrome plating improves corrosion resistance, acid resistance, scale resistance, etc.

Chrome plating of medium and high carbon steels increases hardness and wear resistance.

During chemical-thermal treatment, diffusion alloying of the surface layers of the treated metal or alloy with chromium makes it possible not only to sharply increase the strength characteristics, but also to change the chemical and physical properties.

Chemical-thermal treatment is a heat treatment, which consists in a combination of thermal and chemical effects in order to change the composition, structure and properties of the surface layer of steel.

During chemical-thermal treatment, the steel is saturated with the corresponding element (for example, chromium, silicon) by its diffusion in the atomic state from the external environment (solid, gas, steam, liquid) at high temperature.

Chemical-thermal treatment has found wide application in mechanical engineering.

The widespread use of chemical-thermal treatment is explained by the fact that most parts of machines and mechanisms operate under conditions of wear, cavitation, cyclic loads, corrosion (chemical, electrochemical) at cryogenic or high temperatures, at which maximum stresses occur in the surface layers of the metal. Chemical-thermal treatment, which increases the surface hardness, wear resistance, cavitation and corrosion resistance and creates favorable residual compressive stresses on the surface, increases the reliability and durability of machine parts (for example, Lakhtin, Yu. technical educational institutions - 3rd ed., revised and supplemented - M.: Mashinostroenie, 1990. - 528s: ill., [2]).

So, for example, from the description to the patent of the Russian Federation No. 2607871 (published on January 20, 2017), a method for obtaining a coating on products made of low- or high-alloy steels, or non-ferrous metals or their alloys by applying a metal coating on them by the thermal diffusion method includes the following successive stages: loading workpieces into a constantly rotating container with a simultaneously saturating powder mixture based on chromium powder with an admixture of zinc oxide in the form of a dust cloud formed throughout the container from the specified powder mixture, due to the tribostatic effect, uniform deposition of the saturating powder mixture on the entire surface of the product, while the above loading and deposition is carried out for no more than 15 minutes at a container rotation speed of 7-10 rpm, heating the container with the product in the temperature range from 250 to 500°C at a heating rate of 5-10°C/min and a container rotation speed of 5 -8 rpm at the duration of the heating stage n not more than 50 minutes, holding for at least 5 minutes at the indicated temperature conditions and at a container rotation speed of 2-6 rpm and forced cooling of the container with the product when the container rotation speed increases to 7-10 rpm and the temperature decrease speed is 5-10 °C/min and with a duration of the cooling stage of at least 60 minutes to ensure the production of a coating with a thickness of the anti-corrosion layer from 1.5 to 16.0 μm, which is controlled by the duration of the last two stages.

Also known is a method of siliconizing steel products, including electrolysis treatment of products in a salt melt containing a silicon-containing activator, while in order to intensify the process, increase wear resistance and structural strength of the workpieces, the treatment is carried out at a cathode current density of 400-500 A/m ^{2 °} and 1050-1100°C for 0.5-1.0 h (USSR author's certificate No. 1280916, published 06/27/2007).

However, all known methods of diffusion alloying with chromium and siliconizing methods have the disadvantage that alloying and siliconizing are carried out during the production of the corresponding product (corresponding design), and not during its operation.

This shortcoming is manifested in the fact that it is extremely difficult, and sometimes impossible, to do diffusion alloying with chromium and silicon of large-sized structures.

In particular, this applies to the radiant sections of boilers and furnaces. The main reason for the cracking of such pipes (and, consequently, their short service life) is their low corrosion resistance in fossil fuel combustion products. Diffusion alloying with chromium of such pipes can increase their corrosion resistance and, accordingly, increase their service life, however, such alloying in the production process is extremely difficult, requires a radical restructuring of production and significantly increases the cost of finished products, and for this reason is not used on an industrial scale.

However, the known ceramic coating Solcoat containing Cr ₂ O ₃ and SiO ₂ . This coating belongs to the class of highly radiant.

Highly emissive coatings are coatings that change the emissive properties of surfaces. Such coatings are well known. They are applied in various fields, including high-temperature nuclear reactors, photovoltaic solar cells, aerospace engineering, iron and steel industry and petrochemical industry.

Solcoat is a water-based sol-gel ceramic coating using the Solcoat™ component /https://www.ctkeuro.ru/index.php?p=Coating#Slide4/. Such a coating is used to increase the re-emission of thermal radiation.

This is the only known way to use Solcoat for its intended purpose, i.e. high re-emission re-emission.

The result of this use is a reduction in energy losses.

It is known to use the Solcoat ceramic coating obtained by mixing Solcoat components and water, applying the paint obtained by this mixing onto the surface of steel structure elements (Reducing energy consumption and increasing energy efficiency at fuel and energy facilities. Babkin Viktor Aleksandrovich. Achinsk, 10/31/16, JSC ANPZ VNK, publication date 12/31/2019, http://www.ipktek.ru/templates/new_style_1/images/konkurs_2016/sec15/prod/pr.pdf). This information is accepted as the closest analogue to the patented solution.

However, the use of this technology for alloying steel structures during their operation is not known.

Disclosure of invention

The technical result of the claimed invention is the simplification of diffusion alloying of steel structures with an increase in hardness and wear resistance, and hence durability, including long structures, by providing the possibility of alloying during their operation, while alloying occurs with an increase in the diffusion layer in the process. simultaneous joint diffusion alloying of elements with chromium and silicon. In addition, the technical result is the expansion of the scope of the ceramic coating, while the Solcoat coating in this case of its application is not highly radiant.

The technical result is achieved through the use of Solcoat ceramic coating for simultaneous joint diffusion alloying with chromium and silicon during operation of the surface of elements containing iron, obtained by mixing Solcoat components and water, and deposited on the surface of elements operated at temperatures not lower than 300 ° C and not more 560°C, followed by annealing to a temperature not lower than the temperature of evaporation of water from the coating (up to 120°C).

At the same time, an unexpected effect revealed during operation is that diffusion alloying of steel structure elements containing iron and operated at temperatures not lower than 300°C and not higher than 560°C occurs during their operation.

Solcoat components and water are mixed in proportions specified by the Solcoat manufacturer, and annealing is carried out in a working gas atmosphere for these elements of steel structures. The result of this mixing is a paint that, after being applied to the steel and the water added by mixing with the Solcoat components, evaporates from it, becomes a ceramic coating.

The Solcoat coating is a heat-resistant, gas-tight ceramic composite (up to 1900°C). It has high corrosion resistance in acid gases and condensates. Solcoat is ablation resistant and prevents scale formation.

The Solcoat coating, depending on the composition of the components used in its manufacture, can be in various forms, for example:

- green - with increased corrosion and heat resistance,

- black - with increased resistance to abrasion at lower temperatures - CroMag - with an increased temperature limit of use.

Solcoat is made from a water-based paint obtained by mixing Solcoat components in water.

The paint can be applied by air and/or airless spray.

When obtaining a highly radiant coating in the technological process of its baking and heating, there are three characteristic temperatures of the technological process of creating the coating. It:

Температура изготовления краски;

Paint manufacturing temperature;

Температура запекания - это температура завершения выпаривания свободной (то есть не химически связанной) воды из краски. Это температура, при которой завершается выпаривание воды, которая была добавлена при приготовлении краски;

The bake temperature is the temperature at which the free (i.e., non-chemically bound) water is completely evaporated from the paint. This is the temperature at which the evaporation of the water that was added during the preparation of the paint is completed;

• Maturing temperature is the heating temperature of the coating, above which the coating acquires a high emissivity (re-radiates with a high re-radiation coefficient). The acquired high emissivity is irreversible, that is, when the coating is cooled, it does not lose this previously acquired property.

In addition, there are two temperature ranges - the temperature range for evaporating free water from the paint and the temperature range for evaporating chemically bound water from the baked coating.

In the process of heating applied to the surface of the paint, its physical properties change.

The first change occurs when free water boils and evaporates. This change consists in the fact that the paint applied to the base becomes baked with the base on which it is applied, the coating. However, the Solcoat coating does not yet have high emissivity properties.

With a further increase in temperature, the gradual evaporation of chemically bound water begins, which occurs due to the breaking of chemical bonds in the coating, leading to a change in its chemical composition and accompanied by the formation of water.

At this stage, at temperatures ranging from 300°C and above (up to 560°C), Cr ^-3 is formed and diffusion saturation of the surface layer of the metal with chromium atoms (Cr ^-3 ) occurs. Due to the high pH of the coating, the “dissolution” of the surface layer of the metal occurs, that is, the metal surface is brought to a chemically active state. This surface layer of metal is subject to ionic diffusion of ions (Cr ^-3 ) from the coating. As a result, the surface of the metal is saturated with chromium.

At temperatures ranging from 300°C, chemical-thermal treatment of the metal takes place, at which the metal is saturated with chromium. This chemical-thermal treatment of metal includes three successive stages:

The first stage is the formation of active Cr ^-3 atoms in the coating (saturating medium) near the surface or directly on the surface of the metal. Diffusion flow power, i.e. the number of active Cr ^-3 atoms formed per unit time depends on the composition and state of aggregation of the saturating medium (Solcoat coating), the interaction of the individual components of the medium with each other, temperature, pressure and steel composition. This stage starts at a Solcoat coating temperature of 300°C.

The second stage is the adsorption (sorption) of the formed active Cr ^-3 atoms on the saturation surface (metal surface). Adsorption is a complex process that occurs on the metal surface in a non-stationary manner. There are physical (reversible) and chemical adsorption (chemisorption). During chemical-thermal treatment, both types of adsorption are superimposed on each other. Physical adsorption leads only to the adhesion of the adsorbed atoms of the saturating element (adsorbate) - Cr ^-3 with the treated surface (adsorbent) - metal due to the action of van der Waals forces of attraction, and it is characterized by an easy reversibility of the adsorption (desorption) process. During chemisorption, an interaction occurs between the atoms of the adsorbate (Cr ^-3 ) and the adsorbent (metal), which in its nature and strength is close to chemical (Heat treatment in mechanical engineering Handbook Edited by Yu. M. Lakhtin, A. G. Rakhshtadt. Moscow, Publishing house "Mashinostroenie", 1980 - 783 pages [3]).

Adsorption begins, first of all, in those areas of the metal surface, the energy of which is maximum. Adsorbed atoms are retained on the surface due to the desire of the system to reduce the amount of free energy. Adsorption is always an exothermic process leading to a decrease in free energy.

If the chemical potential of the diffusing element (Cr ^-3 ) in the coating is higher than in the treated metal, the adsorbed atoms are absorbed by the treated metal, penetrating into lattice vacancies that are present in large numbers on the metal surface.

The difference between the chemical potentials of the saturating medium (coating) and the treated metal serves as a thermodynamic stimulus for the chemical-thermal treatment process.

The adsorption capacity of the treated surface (metal) depends on the temperature, pressure, surface condition, nature of the metal and the diffusing element, and other factors.

The third stage is diffusion - the movement of adsorbed atoms in the lattice of the treated metal. As the atoms of the diffusing element (Cr ^-3 ) accumulate on the saturation surface, a diffusion flow occurs from the surface deep into the metal (product) being processed.

The diffusion process is possible only if there is a solubility of the diffusing element in the treated metal and a sufficiently high temperature that provides the necessary energy to the atoms [3].

These stages of the saturation process are interrelated and affect the kinetics of chemical-thermal treatment, the phase composition and structure of the diffusion layer, and, consequently, its properties.

The development of the diffusion process leads to the formation of a diffusion zone in the surface layers of the treated metal, consisting of solid solutions or chemical compounds.

A layer of metal material near the saturation surface, which differs from the initial one in chemical composition, is called a diffusion layer. The material of the part under the diffusion layer, not affected by the influence of the surrounding active medium, is called the core.

The intensity of chemical-thermal treatment is determined mainly by its diffusion stage. Diffusion is understood as the movement of atoms in a crystalline body to distances exceeding the average interatomic of a given metal.

The main type of thermal motion of atoms in a crystal lattice is their oscillations around the equilibrium position.

The diffusion process is based on an atomic mechanism, in which each atom performs more or less random walks, i.e. a series of jumps between different equilibrium positions in the lattice.

To implement an elementary act of diffusion, an atom must overcome an energy barrier, the value of which is determined by the activation energy Q. The average thermal energy of atoms E _Q is always less than the value of Q and is linearly related to the temperature E _Q = 3kT, where k is the Boltzmann constant.

Thus, the activation energy Q is the amount of energy fluctuation required for an atom to move from one position in the crystal lattice to another.

An elementary act of diffusion in the vacancy mechanism is carried out by moving an atom to a neighboring vacancy and forming a new vacancy in the old place, etc. Thus, continuous diffusion of vacancies occurs [3].

In metals, during the formation of substitution solid solutions, diffusion is predominantly carried out according to the vacancy mechanism.

Diffusion alloying with chromium of metals coated with Solcoat occurs starting from 300°C and up to the maturation temperature, which is equal to 560°C. Starting from the maturation temperature, structural changes occur in the coating, which lead to the appearance of highly emissive properties in the coating. Thus, the maturation temperature is the temperature above which irreversible changes begin in the Solcoat coating, manifested by the appearance of a high re-emissivity in the coating.

When pure iron is saturated with various elements, the structure of the emission layer obeys the general rule. According to this rule, diffusion between two components causes the formation of single-phase layers, corresponding to single-phase regions of the Fe-Me phase equilibrium diagram, crossed by an isotherm at saturation temperature. Diffusion layers are formed in the same sequence as the single-phase regions on the state diagram.

Consequently, the nature of the primary formations, the phase composition and the change in concentration along the depth of the diffusion layer can be described by the state diagram: iron is a diffusing element [3].

In the case of a phase diagram with a closed region of the γ-phase (Fe-Cr), diffusion initially proceeds in the γ-phase, and upon reaching the solubility limit on the surface, phase recrystallization γ -> α occurs

Nuclei of the α-phase are formed on the surface at the points of emergence of grain boundaries, blocks, accumulation of dislocations and other structural defects, where saturation of the γ-phase with a diffusing element is achieved more quickly, fluctuations of concentrations and energy, which are necessary for the formation of an α-phase nucleus of a critical size and less the work of his education. Since oversaturation exists only on the surface, the α-phase forms a continuous layer. As long as only the γ-phase exists, the concentration of the diffusing element gradually decreases from the surface inwards. The formation of the α-phase leads to an abrupt increase in the concentration (chemical potential) by a value corresponding to the width of the two-phase region α + γ.

The jump in concentration occurs due to the fact that two-phase regions α + γ cannot be formed by diffusion. This is explained by the fact that within the two-phase region, the compositions of the phases are constant and the concentration gradient within each of them is equal to zero. An interphase boundary appears between the α-phase formed on the surface and the underlying γ-phase.

In the α-phase formed on the surface, and in the underlying γ-phase, diffusion of the saturating element occurs, which tends to change the established concentration on the interfacial surface. This leads to the development of interfacial diffusion, i.e. the transition of atoms of the diffusing element from the α-phase to the γ-phase, which restores the boundary concentrations at the interface and moves it deep into the metal being processed. The growth rate of the α-phase will be the higher, the greater the mobility of the diffusing element in it and the slower the diffusion in the γ-phase proceeds.

The nuclei of the α-phase grow in the direction of diffusion, forming characteristic columnar crystals, since the supersaturation necessary for their growth is achieved at the point of contact of the α- and γ-phases (Processes of mutual diffusion in alloys / I.B. Borovsky, K.P. Gurov, I. D. Marchukova, Y. E. Ugaste, Moscow: Nauka, 1973, 360 p., [4]).

The thickness of the diffusion layer, which determines the depth of the hardened layer, is the most important characteristic of chemical-thermal treatment. The layer thickness is determined (Shinyaev, A.Ya. Diffusion processes in alloys / A.Ya. Shinyaev. - M.: Nauka, 1975. - 228 p., [5]):

Температурой насыщения;

saturation temperature;

Продолжительностью процесса;

duration of the process;

Перепадом концентрации по глубине слоя;

The difference in concentration over the depth of the layer;

Составом стали.

Steel composition.

In most cases, the increase in the effective thickness of the diffusion layer obeys the parabolic dependence

x ² = kt

where x is the thickness of the diffusion layer; k is a constant, which includes the diffusion coefficient (cm ² /s)‚ depending on the specific conditions of the chemical-thermal treatment; t - time.

The constant k‚ and, consequently, the layer thickness depend exponentially on temperature.

Thus, the longer the process of emission doping and the higher the operating temperature, the thicker the diffusion layer.

This means that the longer the metal coated with Solcoat is in operation in the temperature range from 300°C to 560°C, the thicker the diffusion layer. Diffusion alloying with chromium occurs continuously during operation with a gradual increase in the diffusion layer.

With a further increase in temperature, starting from 560°C and above, the chromium oxide contained in the coating passes from the amorphous state to a glassy plastic low-viscosity state and in this state fills all the pores that were previously formed during the evaporation of chemically bound water. As a result, the coating becomes gas-tight and additional protection against aggressive environments is formed.

Solcoat Baking on the surface of steel or other surface occurs at the baking temperature.

The baking temperature is the temperature at which the process of evaporation of free water from the paint is completed (up to 120°C).

Baking consists in the rigid adhesion of the coating to the surface of the base on which it is applied (metal) and occurs when water evaporates from the paint applied to the metal. Hardening is completed when the water is completely evaporated. Up to this point, the paint remains plastic and hardens as it evaporates.

IMPLEMENTATION OF THE INVENTION

The invention can be carried out, for example, in radiant convection ovens by applying a Solcoat coating to steel coils.

To implement the proposed method, at the first stage, the surface of the coil (steel pipes) is prepared for coating with Solcoat. To do this, the pipes are cleaned of contaminants and dedusted.

Further, to obtain a coating, the components of Solcoat in the proportions recommended by the manufacturer are mixed with water.

In particular, the Solcoat components and water are mixed in proportions:

Two SOLCOAT Part A : One SOLCOAT Part B : One SOLCOAT Part C.

Mixing is carried out at the place of application of the coating, for example, as recommended by the manufacturer Solcoat, using a screw mixer for 45 minutes. The paint obtained by such mixing can be used within 12 ÷ 24 hours. The paint is applied immediately to the prepared surface in several (2÷4) layers. The final thickness should be 0.12÷0.25 mm. The time between applying layers can be from 30 minutes to 4 hours.

When preparing a Solcoat paint composition for chromium diffusion alloying, the proportion of water can be different, but such that the acidity (pH) of the paint should not be less than recommended by the Solcoat manufacturer, on average, in the range of 7-11.

When preparing paint, it must be taken into account that when water is added to the powder mixture, the cohesiveness of the powder mass increases, and this causes a higher resistance to mixing. Therefore, wet mass torque measurement is consistent with different stages of fluid saturation [R.C. Rowe, G.R. Sadeghnejad, The rheology of microcrystalline cellulose powder/water mixes - measurement using a mixer torque rheometer, International Journal of Pharmaceutics, 38 (1987) 227-229]. There are four phases of liquid-solid interaction, namely pendulum, funicular, capillary and drip phases. When water is added, the torque of the wet mass increases as the saturation with liquid passes through the pendulum phase and the funicular mass phase of the funicular. The maximum torque approximately corresponds to the capillary phase [B. Hancock, P. York, R. Rowe, An assessment of substrate-binder interactions in model wet masses. 1: Mixer torque rheometry, International Journal of Pharmaceutics, 102 (1994) 167-176.]

The baking of the Solcoat paint applied to the coil can be carried out during the start-up and drying of the radiative convection tube furnace, as illustrated in Fig. one.

It follows from this graph that when the furnace is started in the range from 300°C to 471°C, diffusion alloying of pipes with chromium will occur.

To confirm diffusion chromium plating, experiments were carried out with five types of steel.

The steel grade ASTM A335 Grade P9 (in Russia, an analogue is produced - steel of the X9M grade) was investigated after its chromium plating according to the claimed method on coil pipes made of such steel, in real operating conditions of these pipes of a radiation-convection tube furnace after applying Solcoat coating to the pipes. The period of operation was five years. Five years after the serpentine tubes were coated with Solcoat during routine maintenance, the serpentine tube was replaced with a new one, after which a piece was cut out of it for research. Simultaneously with the application of the Solcoat coating on the ASTM A335 Grade P9 steel coil pipe, the coating was also applied on 4 steel plates of the following steel grades: 08ps, 20, 09G2, 12Kh1MF. These plates were in an oven running an ASTM A335 Grade P9 steel coil coated with Solcoat. The plates were in close proximity to the coil. They were taken for research simultaneously with the decommissioned coil pipe.

Alloy steels are marked with numbers and letters indicating the approximate composition of the steel. Two-digit numbers (for example, 12ХН3А) are given at the beginning of the stamp, indicating the average carbon content in hundredths of a percent. Russian letters to the right of the number indicate the alloying elements that make up the steel. The letter "X" means alloying with chromium.

In accordance with these marking rules, among the steel samples that have been coated with Solcoat are ASTM A335 Grade P9 steel and 12Kh1MF steel.

ASTM A335 Grade P9 is applied for seamless alloy steel ferrite tubes for high temperature service. This steel contains 8-10% chromium. It is a high chromium alloy steel. Its Russian counterpart is Kh9M steel.

In the rest of the steel samples, no matter how significant the content of chromium is only in steel 12Kh1MF (0.9-1.2%). The remaining samples contain chromium as an impurity in small quantities: - less than 0.1% (steel 08ps), less than 0.25% (steel 20), less than 0.3% (steel 09G2).

In all steel samples, silicon is contained as an impurity in small quantities.

The study was carried out using a Phenom ProX scanning electron microscope integrated with an energy-dispersive X-ray spectrometer with a silicon drift detector cooled by a Peltier element.

A study on a Phenom ProX scanning electron microscope showed the appearance of a thin layer of chromium in the surface layer.

For ASTM A335 Grade P9 directly on the surface, the chromium content is 20%, which is at least 10% more than the usual chromium content for this steel. Further along the depth from the metal surface, the chromium content decreases to 10% at a distance of 15 µm. The research results are shown in table 1.

Table 1 Steel Maximum increase in Cr on the surface Depth of alloying with chromium Maximum Si gain on the surface Silicon doping depth ASTM A335 Grade P9 ten% 15 µm 75% 3 µm 08ps eight% 15 µm 72% 3 µm twenty 9% 14 µm 71% 3 µm 09G2 ten% 13 µm 74% 3 µm 12X1MF eight% 15 µm 75% 3 µm

The significantly smaller depth of doping with silicon is explained by the fact that the main process in the doping process is the adhesion of adsorbed atoms of the saturating element (Si) to the metal due to the action of van der Waals forces of attraction.

Thus, the conducted studies confirmed the possibility of using the Solcoat coating for diffusion alloying of steels simultaneously with chromium and silicon.

Claims (1)

Application of Solcoat ceramic coating for simultaneous diffusion alloying with chromium and silicon of the surface of structural steel elements during operation at a temperature not lower than 300°С and not more than 560°С.

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