Protective coating on medical instrument

Abstract

FIELD: protective coatings.SUBSTANCE: invention relates to a method for obtaining a wear-resistant coating, including performing a multilayer coating based on nitrides using an ion-plasma technology using three cathodes located in a horizontal plane. The cathodes are located along a circle relative to the centre of the location of the coated object with intervals between them along an arc of 120°. The cathodes are made of a material based on titanium nitride with additives of one of the elements: Al, Cr, Si in an amount from 5 mas.% to 20 mas.%. The thickness of each coating layer is changed from 0.4 mcm to 0.8 mcm. The number of layers is from 3 to 5. Each layer is applied by modulating sublayers with a period of 50 nm - 150 nm, while the cathode current is maintained in the interval from 90 A to 120 A, the voltage between the cathode and the surface of the coated object is changed in the interval from 50 V to 80 V.EFFECT: obtaining a wear-resistant coating with high hardness.1 cl, 1 ex

Description

[0001] The invention relates to the production of protective coatings on metallic materials, primarily on stainless steel products, namely on medical instruments made of stainless steel.

[0002] Medical instruments are subject to special requirements due to the specific nature of their use. One such requirement is surface cleanliness, specifically the absence of surface defects, such as scratches, nicks, and pitting, which can act as contaminant reservoirs. There are two aspects to addressing this issue. The first is the production of products with a high surface cleanliness. The second is preventing surface damage during use, which can occur due to impacts, drops, or scratches. Preventing surface damage is typically achieved by applying protective coatings to the surface of medical instruments. In practice, such coatings are primarily wear-resistant, i.e., resistant to abrasion. A characteristic property of such coatings is increased hardness, which, in our case, characterizes wear resistance and, in this sense, protects the surface of medical instruments.Among the wear-resistant coatings, nitride, carbide and carbonitride coatings of titanium, aluminum and zirconium are widely known (TiN, ZrN, TiCN, TiC, CrN, AlTiN, ZrAlN, ZrCN, TiO coatings. / [Electronic resource] - URL: https: / / hrom-prom.ru / поклады-tin-zrn-ticn-tic-crn-altin-zraln-zrcn-tio / / (date of access 09.12.2024). The methods for obtaining such coatings are methods of transfer and deposition through the gas phase, in particular the PVD method (Volkov D.I. Purpose and methods of applying wear-resistant coatings to cutting tools. Rybinsk, 2015 / [Electronic resource] - URL: https: / / www.rsatu.ru / upload / medialibrary / 07f / Naznachenie-i-sposoby-naneseniya-pokrytiy.pdf / (date of access 09.2.2024).

[0003] The closest technical solution to the claimed one is a method for producing a multilayer coating for a cutting tool, including vacuum-plasma application of a two-layer coating, wherein titanium, silicon and iron nitride containing 1.3-1.5% iron is applied as the lower layer, and titanium, silicon and iron nitride containing 0.4-0.6% iron is applied as the upper layer, wherein the coating is applied using three cathodes located in a horizontal plane, of which two opposite ones contain titanium and silicon, and the cathode located between them contains titanium and stainless non-magnetic steel, and when applying the upper layer, all three cathodes are used, and the lower layer is applied using a cathode containing titanium and stainless non-magnetic steel, and one cathode containing titanium and silicon (Russian Federation Patent for Invention No. 2330110, IPC B23B 27 / 14, C23C 14 / 06, published 27 / 07 / 2008).The disadvantage of this technical solution is its insufficient hardness, which leads to the rapid appearance of scratches during use.

[0004] The problem to be solved by the claimed invention is to expand the arsenal of technical means for wear-resistant coatings with high hardness, applied to the surface of stainless steel products.

[0005] The stated technical result in the claimed invention is achieved by implementing a method for producing a wear-resistant coating, which includes producing a multilayer nitride-based coating using ion-plasma technology using three cathodes located in a horizontal plane. The cathodes are simultaneously arranged circumferentially relative to the center of the object being coated, with intervals between them along an arc of 120 °, the cathodes are made from a material based on titanium nitride with additives of one of the elements: Al, Cr, Si in an amount from 5 wt.% to 20 wt.%, the thickness of each coating layer varies from 0.4 μm to 0.8 μm, the number of layers is from 3 to 5, each layer is applied in modulating sublayers with a period of 50 nm - 150 nm, while the cathode current is maintained in the range from 90 A to 120 A, the voltage between the cathode and the surface of the coated object is changed in the range from 50 V to 80 V.

[0006] The claimed invention has the following distinctive essential features: - the cathodes are arranged in a circle relative to the center of the object being coated with intervals between them along an arc of 120 ° ,

[0007] - cathodes are made from a material based on titanium nitride with additives of one of the elements: Al, Cr, Si in an amount from 5 wt.% to 20 wt.%,

[0008] - the thickness of each layer varies from 0.4 μm to 0.8 μm,

[0009] -the number of coating layers is from 3 to 5,

[0010] - each layer is applied by modulating sublayers with a period of 50 nm - 150 nm,

[0011] - the cathode current strength is maintained in the range from 90 A to 120 A,

[0012] - the voltage between the cathode and the surface of the coated object is changed in the range from 50 V to 80 V.

[0013] The given essential features are distinctive from the prototype, since each of them is not contained in the set of essential features of the prototype, i.e. is not present in the list of features implemented in the prototype, and is not their characteristic.

[0014] The cathodes are arranged circumferentially relative to the center of the object being coated, with 120° intervals between them. The cathodes are positioned in a single plane perpendicular to the axis of the object being coated when it is stationary, or in a plane perpendicular to the axis of rotation of the object being coated when it rotates during coating. A 120° interval between the cathodes ensures uniform coating of the object being coated.

[0015] Production of cathodes from a material based on titanium nitride with additives of one of the elements: Al, Cr, Si in an amount from 5 wt.% to 20 wt.%, and the cathodes can be made from a single material, and each cathode can be made from an individual composition based on titanium nitride with the specified components. In this way, it is possible to produce coatings with various compositions based on titanium nitride.

[0016] The thickness of each layer varies between 0.4 µm and 0.8 µm, and the number of layers of this coating ranges from 3 to 5. Each layer is applied in modulating sublayers with a period of 50 nm to 150 nm. Coatings produced in this manner have a hardness ranging from 2800 HV to 3400 HV. In this case, a hardness of 2800 HV - 2900 HV is obtained for a coating in 3 layers with a thickness of 0.4 µm and modulating sublayers with a period of 130-150 nm, produced at a cathode current of 120 A and a voltage between the cathode and the surface of the coated object of 50 V. A coating with a hardness of 3300-3400 HV is obtained by producing 5 layers with a period of modulating sublayers of 40-50 nm at a cathode current of 90 A and a voltage between the cathode and the surface of the coated object of 80 V.

[0017] The number of coating layers, their thickness, and the period of the modulating sublayers affect the coating hardness. Increasing the number of coating layers to 5 with a thickness of 0.4-0.8 μm increases the coating hardness. Increasing the number of layers above 5 has virtually no effect on the coating hardness. Reducing the number of layers below 3 reduces the coating hardness. A period of modulating layers in the range of 40-150 nm is optimal for ensuring high coating hardness; this period is selected experimentally. Optimal cathode current values ​​during coating application are 90-120 A, with an increase in current in this range leading to an increase in the crystallite size in the coating, which in turn reduces the hardness. Conversely, increasing the voltage between the cathode and the surface of the coated object in the range of 50-80 V reduces porosity and, accordingly, increases the coating hardness, but only slightly, within the range of 50-60 HV.

[0018] The claimed invention is industrially applicable in the field of metal surface protection by coating and can be used in mechanical engineering fields related to the protection of metals by coating. The claimed technical solution can be implemented by appropriately trained specialists. Industrially produced and commercially available devices, instruments, and materials are used in the implementation of the claimed technical solution. The methods for implementing the process flow of the invention are the physicochemical processing of metallic and ceramic materials, namely, the surface treatment of metallic and metal-ceramic products using ion-plasma spraying methods. The means for implementing the invention are ion-plasma spraying units with programmable process modes.

[0019] The above set of essential features of the claimed invention and their disclosure allows us to draw a conclusion about the implementation of the purpose of the invention, i.e. on achieving a technical result.

[0020] Thus, it has been demonstrated that the set of essential features of the claimed invention, which enables the claimed technical result to be achieved, differs from the set of essential features of analogs, the prototype, and other known sources of data. This means that the application of this set of essential features to achieve the claimed technical result is unknown. In other words, the claimed invention is not known from the prior art.

[0021] A study of the state-of-the-art in applying wear-resistant or high-hardness coatings to metals, particularly stainless steel, has revealed no technical solutions whose essential features, individually or in combination, coincide with the distinctive essential features of the claimed invention and enable the claimed technical result to be achieved. Therefore, the lack of known influence of the distinctive essential features of the claimed invention on the claimed technical result has been confirmed.

[0022] It should also be noted that the use of the entire declared set of essential features, including the set of distinctive features, to obtain the declared technical result should not be obvious to specialists from the prior art, since it does not constitute a combination, modification or joint use of information contained in the prior art and / or the general knowledge of a specialist.

[0023] The claimed invention - “Protective coating on a medical instrument” is carried out as follows.

[0024] Medical instruments made of stainless steel are placed on a stage or in special holders in the PVD coating unit. Cathodes are positioned in the plane of the stage, perpendicular to the axis, at 120° intervals around the circumference. Each cathode is made of titanium nitride with the addition of one element from the following series: Al, Cr, or Si, in amounts ranging from 5% to 20% by weight. The reaction chamber is then evacuated, argon is introduced, and the instrument surfaces are cleaned by ion etching. The coating process then begins in a nitrogen atmosphere. The coating is performed using a special program that regulates the cathode current and the voltage between the instrument on the stage or in the holder and the cathode. This method coats one side of the instrument. If double-sided coating is required, the instrument is flipped over and the process is repeated.When hanging the object to be coated, a single process is usually sufficient.

[0025] Example

[0026] A pair of 08Kh18N10T stainless steel medical tweezers was suspended in the reaction chamber of a PVD ion-plasma coating system. Three cathodes were positioned in the tool plane, perpendicular to the tool rotation axis. One cathode was made of titanium nitride with 5 wt.% aluminum additives, the next cathode was made of titanium nitride with 10 wt.% chromium additives, and the last cathode was made of titanium nitride with 5 wt.% silicon additives. After evacuating the reaction chamber and adding argon, the tool surface was cleaned by bombarding it with argon atoms. Then, four layers of coating were applied in a nitrogen atmosphere at a pressure of 8 mbar. The first, second, and third coating layers were applied with one of the cathodes turned on sequentially. In this way, coating layers with additives of aluminum nitride, chromium nitride, and silicon nitride were obtained.The cathode current was 110 A, the voltage between the cathode and the surface of the object being coated was 60 V, and the modulating layer period was 70-85 nm. The fourth top coating layer was applied with all cathodes turned on. The cathode current was 100 A, the voltage between the cathode and the surface of the object being coated was 80 V, and the modulating layer period was also 70-85 nm. The application time for each layer was 5-7 minutes. The hardness of the resulting coating was 3100-3150 HV.

[0027] The above embodiment of the coating should not be construed as limiting the scope of the invention. On the contrary, variations, modifications, and equivalents of the described examples are also possible within the scope of the rights set forth in the claims.

[0028] The above description of the invention and its implementation examples confirm the achievement of the stated purpose during the implementation of the invention while implementing all of its essential features. They also demonstrate the cause-and-effect relationship between the essential features and the achieved technical result.

Claims

A method for producing a wear-resistant coating, including the production of a multilayer coating based on nitrides using ion-plasma technology using three cathodes located in a horizontal plane, characterized in that the cathodes are arranged circumferentially relative to the center of the object being coated with intervals between them along an arc of 120°, the cathodes are made of a material based on titanium nitride with additives of one of the elements: Al, Cr, Si in an amount of from 5 wt.% to 20 wt.%, the thickness of each coating layer varies from 0.4 μm to 0.8 μm, the number of layers is from 3 to 5, each layer is applied in modulating sublayers with a period of 50 nm - 150 nm, while the cathode current is maintained in the range of 90 A to 120 A, the voltage between the cathode and the surface of the object being coated is changed in the range of 50 V to 80 V.