CS276840B6 - Method for applying coatings to articles - Google Patents

Abstract

The solution relates to a device for applying coatings to products by a physical method from the gas phase in those types of coating devices where the evaporation of one or more components of the coating occurs using a direct current low-voltage arc. The device consists of a system for evaporation of the coating material, a coating chamber (6) with a space (5) for placing the coated material, a vacuum apparatus and an electrical source for coating. The essence of the solution is that in the coating chamber (6) the space (6) for placing the coated material is arranged in its circumference and the cooled metal cathode (1) is placed in its center or near it.

Description

The invention relates to a device for applying coatings to articles by a physical gas phase method, consisting of a system for evaporating the coating material, a coating chamber with a space for accommodating the coated material, a vacuum apparatus and an electrical source for the coating.

At present, an arrangement of the individual elements of this type of coating device is used such that the evaporated cathodes are located in the region of the coating chamber shell, while the coated material is located in the center of the chamber on a rotating holder. A DC low voltage arc burns between the metal cathode and the coating chamber shell. The metal cathode is connected to the negative pole and the chamber to the positive pole of the low voltage arc source. The discharge of the low-voltage arc burns at low pressure in the coating chamber (usually less than 1 Pa) on the anode over its entire surface, while on the cathode only at the moment of the moment of occurrence of the moving cathode spot. At the location of the cathode spot, the temperature reaches a value in the range of approximately 5,000 to 10,000 K. At this location, the cathode material evaporates intensively. Vapors evaporated by a low-voltage arc are strongly ionized (in the order of tens of percent) in this discharge. By the negative voltage applied to the sample holder, positively charged ions are drawn from this low-voltage arc, which are applied to the coated material while heating the material to the desired temperature. If a reaction gas is admitted to the coating chamber, a layer of a compound consisting of a material evaporated from the cathode surface and a reaction gas (e.g., a titanium nitride (TiN) layer) can be obtained on the coated material.

The disadvantage of this conventional arrangement of the individual elements of the coating device is the need to move the coated components during coating in order to ensure a uniform rate of coating growth on all coating objects. This complicates the method of measuring temperature during the coating process.

Another disadvantage is the relatively small capacity of the coating equipment, which significantly increases the cost of coating.

Another disadvantage of this device lies in the problematic maintenance of the temperature, especially at higher values. The design of the device causes significant heat loss from the coated material by thermal radiation. This fact is particularly pronounced when coating sintered carbide material, where it is more appropriate to apply coatings at higher temperatures. Coating these materials at temperatures around 600 to 700 ° C would increase the electricity consumption disproportionately.

These disadvantages are eliminated by a device for applying coatings to products by a physical gas phase method, consisting of a system for evaporating the coating material, a coating chamber with a space for placing the coated material, a vacuum apparatus and an electrical coating source according to the invention. that in the coating chamber a space for accommodating the coated material is arranged around its circumference and the cooled metal cathode is located in its center, or

The advantage of the new type of coating device according to the invention is that most components do not need to be mounted on a movable holder, while the uniformity of the applied layer is maintained throughout the batch. At the same time, the temperature of the coated components during the process can be easily measured (and thus precisely regulated).

Another advantage is to increase the capacity of the device at the same chamber volume approximately 2.5 times.

* its proximity.

By suitable thermal insulation of the recipient it is possible to reduce heat losses and apply coatings at higher temperatures (about 600 to 700 ° C) than in the classic type of equipment (about 450 ° C). This fact is especially important for the coating of sintered carbide tools, because increasing the coating temperature increases the cohesiveness of the coating with the substrate material.

The attached drawing shows an example of the structural arrangement of the individual elements inside the coating chamber.

The basis of the device is a system for evaporating the coating material, consisting of a cathode 1, an anode 2, a shield 3 and an ignition electrode 4, located in the middle of the coating chamber. The vaporized material which forms the cathode 1 during the combustion of the low voltage arc is cooled by the water supplied by the cooling system 10. The low voltage arc source has a negative pole connected to the cathode 1. positive pole to the anode 2. . The shield 3 can be connected to the anode 2 at a floating potential or can be connected by a suitable resistor. The bell recipient designed as a coating chamber 6 is vacuum-sealed on the flange 7. The coating chamber shell 6 is earthed, can be at a common potential with the anode 2. works as follows. With the vacuum apparatus 8, the coating chamber 6 is evacuated to the desired vacuum. Reaction or inert gas may or may not be admitted to the plant. Cathode 1 and anode 2 are connected to a DC low voltage arc source. The ignition electrode 4 fires a low voltage arc. The cathode spot burning in the DC low voltage arc will move over the entire surface of the outer cylindrical part of the cathode 1, thus ensuring a uniform application of the coating in the space 5 for placing the coated material. The movement of the cathode spot on the faces of the cathode 1 is prevented by shielding 3. A coating voltage is applied between the anode 2 and the samples in the region 5 so that there will be a positive pole on the anode 2 of the DC low voltage arc and a negative pole on the samples. The negative voltage applied to the samples will regulate the temperature of the coated parts during the process. By this voltage, positively charged ions of the material evaporated from the cathode 1 are pulled out of the combustion space of the low-voltage arc 9 and accelerated towards the samples. On the samples, the coating formed by the evaporated material of cathode 1 or the reaction gas (for titanium (Ti) cathode) grows, and nitrogen increases on the samples as a coating of titanium nitride (TiN) introduced into the chamber.

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The device is especially suitable for coating sintered carbide material. By applying a magnetic field to the cathode region, the lines of force of which run parallel to the axis of the cathode, it is possible to accelerate the movement of the cathode spot, and thus to improve the evaporation of the cathode. The application of such a magnetic field is particularly important in the case of coating steel tools.

Claims (1)

PATENT CLAIMS Apparatus for applying coatings to products by a physical gas-phase method, consisting of a system for evaporating the coating material, a coating chamber with a space for accommodating the coated material, a vacuum apparatus and an electrical source for coating, characterized in that in the coating chamber (.6 ), the space (5) for placing the coated material is arranged around its circumference, and the cooled metal cathode (1) is located at or near its center.