RU2677551C1 - Method of spraying electrically conducting metal-carbon multilayer coating on tape substrate made of nonwoven fibrous material - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to the deposition of an electrically conductive metal-carbon multilayer coating on a tape substrate made of nonwoven fibrous material, comprising the flow of working gas into a vacuum chamber with a substrate and ion-plasma deposition of coating layers on a tape substrate moving at constant speed with magnetron sputtering. Spraying of the coating layers onto a tape substrate moving at a constant speed is carried out by means of at least two magnetrons containing targets made of metal and carbon. Magnetrons are supplied with a constant voltage in a pulsed mode by asymmetrically switching the supply voltage on the target with a time-out ratio on a metal target longer than on a carbon target, until molecular layers of metal-carbon coating on a given substrate are obtained.

EFFECT: ensures uniformity and uniformity of coverage.

5 cl, 5 dwg, 2 tbl

Description

The invention relates to the field of vacuum engineering and technology for producing nanostructures, and in particular to a method of magnetron sputtering on tape substrates of electrically conductive films and can be used to obtain functional coatings in the production of electronic materials, namely for the manufacture of capacitors, supercapacitors, batteries, protective shields and the like products.

Known methods of ion-plasma spraying on a tape substrate (roll material) of thin films (patent RU No. 2398045, publ. 08/27/2010), (patent RU No. 2505256, publ. 01/27/2014), in which for surface modification coiled textile material is degassed on the surface by evacuating the chamber with the material to be processed and subsequent coating on its surface by magnetron sputtering. Moreover, in the process of evacuation, the material is processed in a low-temperature plasma of a glow discharge of a non-polymerizable gas. Coatings are applied to the surface of the material - thin films of copper, aluminum, titanium, brass, silver, gold, stainless steel, bronze and other metals, their alloys and metal compounds, for example, titanium nitride, titanium dioxide, aluminum oxide.

The disadvantage of these methods is that before applying the coating, the process of degassing of the material is carried out by evacuating the working chamber with the processed material to the required pressure, which takes a large amount of time, significantly exceeding the spraying process itself by 3-5 times or more. In addition, the above method does not allow to obtain coatings of a combined composition.

A known method of producing carbon nanostructures, such as carbon globules and carbon nanotubes of various shapes (patent RU No. 2355625, publ. 05/20/2009). The method includes magnetron sputtering on a substrate at constant current in a vacuum chamber in an atmosphere of inert gas of carbon films with nanotubes. In this case, a substrate is used made with predetermined protruding irregularities of its surface. Before magnetron sputtering, a catalyst is applied to the substrate in the form of a thin metal film. The substrates used are mica, aluminum or polycor coated with a chromium film, which was coated with a thin layer of gold. A thin layer of gold is sprayed by thermal heating of gold in a vacuum chamber, followed by annealing of the substrates. The substrates are placed in a vacuum installation for magnetron sputtering of a carbon film in a residual inert gas atmosphere.

However, this method also requires time for spraying a gold layer, annealing the substrate and does not allow coating on moving tape substrates of non-woven fibrous material. The coating of such substrates is an important technological task for the manufacture of various materials.

As a prototype, you can choose the method of deposition of an electrically conductive metal-carbon multilayer coating on a tape substrate of non-woven fibrous material (WO 2016155448, publ. 06.10.2016). In this method, the surface of the substrate is cleaned. The substrate is a non-woven material of chemical fiber or a cotton non-woven material. Then, the working gas is fed into a vacuum chamber with a substrate - argon or nitrogen, and ion-plasma spraying of the coating layers onto a tape substrate moving at a constant speed by magnetron sputtering is performed to obtain a nanometric coating layer with a nanoparticle size of less than 100 nm. The speed of movement of the substrate is 0.5-10.0 m / min.

However, this method does not allow to obtain a nanometric coating of combined composition of a given thickness on a substrate of nonwoven fibrous material with the formation of a continuous conductive surface.

The technical task of the invention is to provide a method that allows to obtain a nanometric coating of a combined composition with a uniform coating of fibers on a tape substrate of nonwoven fibrous material and obtaining a conductive surface that provides effective corrosion protection.

The problem is solved in that in the method of spraying an electrically conductive metal-carbon multilayer coating on a tape substrate of non-woven fibrous material, the working gas is supplied to the vacuum chamber with the substrate and ion-plasma spraying of the coating layers on the tape substrate moving at a constant speed by magnetron sputtering. What is new is that the coating layers are sprayed onto a ribbon substrate moving at a constant speed by means of at least two magnetrons containing targets of metal and carbon, while magnetrons are supplied with a constant voltage in a pulsed mode by asymmetric switching the voltage supply to the targets during duty cycle time on a metal target is longer than on a carbon target until molecular weight layers of a metal-carbon coating are obtained on a tape substrate of a given thickness. In addition, before ion-plasma spraying of the coating, the nonwoven fibrous material is treated with one of the magnetrons with a reverse polarity of the supply on it. Switch the voltage supply to each target with a frequency of 20 -40 kHz, with a substrate moving speed of 4 m / min, the duty cycle of voltage supply to the metal target is 50-70%. As the target metal, a metal selected from the group including titanium, magnesium, aluminum, stainless steel is used, and argon is used as the working gas.

The invention is illustrated by drawings, where in FIG. 1 is a diagram of a magnetron sputtering vacuum installation that is used to perform this method; FIG. 2 is a graph of the thickness of the sprayed film versus the number of layers applied, FIG. 3 is a depiction of the morphology of a sample of non-woven fibrous material without spraying at a magnification of 20,000 times, in FIG. 4 is a depiction of the morphology of a sample of nonwoven fibrous material with spraying (50 passes) with an increase of a) 20,000 and b) 50,000 times, in FIG. 5 - image of the morphology of the sample of non-woven fibrous material with spraying (70 passes) with an increase of a) 20,000 and b) 50,000 times.

The method of ion-plasma vacuum spraying on tape substrates of thin films is carried out in a vacuum installation for magnetron sputtering of thin films (Fig. 1), containing at least two magnetron sputtering devices 1 (magnetron) located in series along the working chamber above the tape substrate 2. In the working The camera also has a system for moving 3 ribbon substrates along the working chamber. As the tape substrate use non-woven material of any fibrous composition, one layer of which has a paper base. From the working chamber, air is pumped out and the working gas is puffed, for example, argon, for example. The working chamber is pumped out to a pressure of 10 ⁻³ Pa and the working gas is supplied until a pressure of 2.7 × 10 ⁻¹ to 3.5 × 10 ⁻¹ Pa is obtained, depending on the target material used. In an inert gas, magnetron sputtering of a thin film is carried out. Before spraying, the tape substrate is treated with one of the magnetron sputtering devices, reversing the supply polarity on it. In the formed low-temperature plasma of a glow discharge of an inert gas under the influence of active particles, the adsorbed gases and water are desorbed from the surface and internal pores of the processed material, as a result of which the process of its degassing and purification takes place. Then a constant voltage of up to 1000 V is applied between the cathode and anode to both magnetrons and a glow discharge is ignited under the targets. As a result of ion-plasma sputtering, the substrate surface is further activated and a thin coating layer of two magnetron targets made of different materials is sprayed onto the tape substrate moving at a constant speed — one target is made of metal and the other is made of carbon. Of the metals for the manufacture of the target, for example, titanium, magnesium, aluminum, stainless steel can be used. During the deposition process, a constant voltage supplied to the magnetron targets is switched at a frequency of 20-40 kHz. In this way, dual (“dual”) magnetron sputtering systems are used, consisting of two identical and adjacent magnetrons operating in turn in a pulsed mode. When a pulsed bipolar voltage of 20-40 kHz is applied to a dual magnetron, the system starts to work in the following mode: in half the period, one magnetron works as the cathode, and the other as the anode, and vice versa in the second half of the period. To turn on the pulsed mode, high-voltage switches are used to power the magnetrons. In the process of spraying, when the substrate ribbon passes through the zone of operation of magnetic spraying devices, a thin coating layer is formed on the surface of the substrate containing elements (molecules and atoms) of materials from which the targets are made. Sprayed materials from different targets are mixed during spraying in the space under the targets and deposited on the substrate, creating a uniform coating of a given multicomponent composition. The metal atoms or carbon molecules deposited by ion-plasma sputtering possess, due to the characteristic energy of ion-plasma sputtering processes, the collision energy of high adhesion to the substrate and, as a result, a dense coating is formed. The pulsed mode of operation makes it possible to obtain a high degree of plasma ionization and completely eliminate the generation of microparticles, which is possible in a conventional magnetron ion-plasma discharge. As a result, a metal-carbon nanocomposite coating structure is formed on the tape substrate with a high degree of uniformity and uniformity, which has a developed surface, which provides highly effective protection against corrosion in the presence of an acid and alkaline medium. For example, an nc-C / nc-Ti combined coating was created, consisting of titanium nanoparticles distributed in a branched nanocarbon matrix, which can be used for down conductors of electrolytic cells of energy storage devices. The switching frequency of the magnetrons linearly depends on the speed of movement of the substrate. At a substrate displacement velocity of 4 m / min, the switching frequency of magnetrons 20–40 kHz was experimentally selected. The pulse voltage is fed asymmetrically to the magnetrons with a duty cycle of supplying a voltage to the metal target longer in time than to the carbon target. Such duty cycle is selected from the condition that the specified thickness of the obtained film depends mainly on the thickness of the conductive metal layer. Metal ions set the parameters of the porosity of the film and its resistance. Carbon molecules create a framework for metal ions in the film. Therefore, it was experimentally selected that metal ions need to be sprayed 2-3 times longer than carbon molecules - this corresponds to a duty cycle for a metal target of 50% - 70%. The movement of the ribbon substrate and magnetron sputtering is carried out until molecular layers of metal-carbon combined coatings of a given thickness are obtained on the substrate. The thickness of the coating layer was measured. The coating thickness depends on the number of passes of the tape substrate under the magnetron targets. The profile of the curve of the coating thickness variation shown in the graph (Fig. 2) indicates that the increase in the coating thickness occurs nonlinearly, stepwise, which means that a loose porous layer of carbon molecules is periodically formed, and during the deposition process, the pores are filled with metal, and the layer is densified and its total thickness grows stepwise as a certain amount of material particles is applied. This confirms that metal ions must be sprayed in time longer than carbon molecules. Selecting the number of passes of the ribbon substrate under the magnetrons, depending on the substrate velocity and the duty cycle for the metal target of the magnetron pulse operation, a predetermined thickness of the obtained film is obtained. Table 1 presents the results of measurements of fiber thickness obtained using scanning electron microscopy (SEM) for four fiber samples with spraying, depending on the number of passes of the ribbon substrate under the magnetrons, substrate speed and duty cycle.

Before the start of sputtering, the parameters of magnetron sputtering and the technological modes of the installation of magnetron sputtering are selected. To determine the technological modes of the installation, glass witness specimens are used, which are placed parallel to the tape substrate in the working spraying chamber. Coatings on glass are available for identification and thorough research. The basic parameters of the resulting films are set — the thickness and surface resistivity. Monitoring and selection of technological parameters is carried out by determining the thickness of the deposited layer by the method of interference using an MII-4 interferometer and the resistance of the deposited layer, which is measured by a two-dimensional probe of the DT 9205ADIGITALMULLTIMETR tester. The obtained research data on witness samples make it possible to determine the magnetron sputtering parameters and operating conditions of the installation: operating current, voltage, pressure in the working chamber, substrate speed, the required number of passes of the roll material under the magnetrons, the switching frequency of the magnetrons and duty cycle, as well as to adjust the technological modes. The parameters of magnetron sputtering also depend on the composition of the material of the metal target.

An example of the parameters of magnetron sputtering and operating conditions of the installation depending on the material of the metal target and the specified thickness of the sprayed film are presented in table 2.

Films obtained by magnetron sputtering on tape substrates of nonwoven fibrous material, depending on the number of passes of the tape substrate under the magnetrons, are shown in FIG. 3-5. In FIG. 3 presents an image (photo obtained by scanning electron microscopy SEM) of a non-woven fibrous material (average fiber thickness of 196 nm) without sputtering at a magnification of 20,000 times, and in FIG. 4-5 - image of samples of non-woven fibrous material with a coating with an increase of a) 20,000 and b) 50,000 times. The number of passes under the targets of the samples shown in these photos corresponds to: FIG. 4-50 passes, FIG. 6-70 passes with a duty cycle of 70%. When comparing images of fibrous materials without spraying and spraying, an increase in the thickness of the fiber with an increase in passages is noticeable, i.e. the increase in the deposited layers of the sprayed film with a uniform coating of the fibers of the substrate material, as well as the formation of a common coating on the fibers to obtain a continuous nanometric uniform uniform coating of a certain thickness. With an increase of × 20,000 times, a decrease in the distance between the fibers, a decrease in the number of gaps between the fibers, and a decrease in the number of through pores are especially noticeable, which indicates a continuous, continuous conductive film on the surface of the fiber, which provides highly effective corrosion protection and conductivity.

Thus, a method has been created that makes it possible to obtain nanometric uniform coatings of a combined composition with a given thickness on a tape substrate of non-woven fibrous material, with a uniform coating of the fibers of the substrate material and obtaining a uniform conductive surface that provides highly effective corrosion protection.

Claims (5)

1. The method of spraying an electrically conductive metal-carbon multilayer coating on a tape substrate of non-woven fibrous material, comprising supplying a working gas to a vacuum chamber with a substrate and ion-plasma spraying of the coating layers onto a tape substrate moving at a constant speed by magnetron sputtering, characterized in that the layers are sprayed coatings on a tape substrate moving at a constant speed are carried out by means of at least two magnetrons containing targets of metal and carbon, while agnetrony supplied DC voltage into a pulsed mode by asymmetric switching energization of the target at the time the duty ratio of metal to the target for more than a carbon target, to obtain a tape substrate molecular layers of metal-carbon coating of given thickness. 2. The method according to p. 1, characterized in that before the ion-plasma spraying of the coating, the nonwoven fibrous material is treated with one of the magnetrons with a reverse polarity of the supply. 3. The method according to p. 1, characterized in that they switch the voltage supply to the target with a frequency of 20-40 kHz, with a substrate moving speed of 4 m / min. 4. The method according to p. 1, characterized in that the duty cycle of the voltage supply to the target of the metal is 50-70%. 5. The method according to p. 1, characterized in that the metal of the target is a metal selected from the group comprising titanium, magnesium, aluminum, or stainless steel, and argon is used as the working gas.

Images