RU2327811C1 - Method for preparation of multi-layer coating for cutting tool - Google Patents

Abstract

FIELD: technological processes, metals processing.

SUBSTANCE: invention is related to methods of vacuum-plasma application of wear resistant coatings on cutting tool and may be used in metals processing. Lower layer of multi-layer coating is made of nitride or carbonitride of titanium, chrome and iron with ratio of, weight % - titanium 87.2-88.7, chrome 10.0-11.2, iron 1.3-1.6, and upper layer - of nitride or carbonitride of titanium, chrome and aluminium with their ratio of, weight % - titanium 75-77, chrome 10.4-11.5, aluminium 12.6-13.5. Application of coating layers is done with three cathodes that are installed horizontally in one plane. The first cathode is made as assembled from titanium and iron, the second one is made as assembled from titanium and aluminum and are installed opposite to the first one, and the third one is made assembled from titanium and chrome and are installed between them.

EFFECT: increase of cutting tool serviceability.

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Description

The invention relates to methods for applying wear-resistant coatings to a cutting tool and can be used in metalworking.

There is a method of increasing the resistance of a cutting tool (RI), in which a wear-resistant coating (PI) of titanium nitride (TiN) or titanium carbonitride (TiCN) is applied on its surface using a vacuum-plasma method (see Tabakov V.P. Performance of a cutting tool with wear-resistant coatings based on complex nitrides and titanium carbonitrides. Ulyanovsk: UlSTU, 1998. 123 p.). The reasons that impede the achievement of the following technical result when using the known method include the fact that in the known method, the coatings have relatively low hardness and level of compressive stresses and insufficient adhesion to the tool base. As a result of this, the coating undergoes more wear and tear, cracks quickly nucleate and propagate in it, leading to the destruction of the coating, which reduces the resistance of the RI with the coating.

The closest method of the same purpose to the claimed invention in terms of features is the method of applying a multilayer coating, disclosed in the description of the patent for the utility model "Cutting tool with a multilayer coating" (RU No. 51999 U1), adopted as a prototype.

For reasons that impede the achievement of the technical result indicated below when using the known method adopted as a prototype, the multilayer coating in the known method contains a lower TiSiN layer having low hardness and adhesion to the tool base. As a result, the coating poorly resists the processes of wear and tear and quickly collapses when cutting. Therefore, the coating should consist of an upper layer with maximum hardness and a lower layer with maximum hardness with maximum adhesion to the tool base.

Recently, the increase in the cost of metal-cutting tools and the tightening of requirements for precision machined parts made the problem of increasing the resistance of radiation sources even more urgent. One of the ways to increase the resistance and, as a consequence, the health of RI with a coating is to apply multilayer coatings with layers with different physical and mechanical properties. The presence in the coating of the upper layer with high hardness, helps to reduce the wear rate of radiation with multilayer coatings. To increase the adhesion strength of the coating to the tool base, it should include a lower layer with improved adhesive properties. In addition, an increase in the hardness of the lower coating layer also contributes to an additional decrease in the wear rate of radiation with multilayer coatings. An increase in the adhesion strength of the layers is ensured by their chemical affinity for each other.

The technical result is an increase in the health of RI. The specified technical result in the implementation of the invention is achieved by applying a lower layer of nitride or carbonitride of a compound of titanium, chromium and iron at their ratio, wt.% - titanium 87.2-88.7, chromium 10.0-11.2, iron 1.3-1.6, and the top layer is made of nitride or carbonitride of a titanium, chromium and aluminum compound at their ratio, wt.% - titanium 75-77, chromium 10.4-11.5, aluminum 12.6-13 , 5, and the application of coating layers is carried out horizontally located in the same plane by three cathodes, the first of which is made of titanium and iron, the second they are molded with a composite of titanium and aluminum and placed opposite to the first, and the third is made with a composite of titanium and chromium and placed between them.

This coating structure allows to obtain high adhesion to the base due to the presence in the coating of the lower layer having high adhesion to the tool base. In this case, the upper and lower layers have high hardness due to the additional alloying of the material of the coating layers and the presence in their structure of micro-layering obtained by coating according to the proposed cathode arrangement.

The analysis of the prior art by the applicant, including a search by patents and scientific and technical sources of information, and the identification of sources containing information about analogues of the claimed invention, allowed to establish that the applicant did not find sources characterized by features identical to all the essential features of the claimed invention. The definition from the list of identified analogues of the prototype, as the closest in the totality of the features of the analogue, allowed us to establish a set of significant distinguishing features in relation to the technical result perceived by the applicant in the claimed method set forth in the claims. Therefore, the claimed invention meets the condition of "novelty."

To verify the compliance of the claimed invention with the condition "inventive step", the applicant conducted an additional search for known solutions in order to identify signs that match the distinctive features of the claimed method of increasing the efficiency of RI, distinctive from the prototype. The search results showed that the claimed invention does not follow explicitly from the prior art for the specialist, since the influence of the transformations provided for by the essential features of the claimed invention on the achievement of the technical result is not revealed from the prior art determined by the applicant. In particular, the claimed invention does not provide for the following transformations:

- the addition of a known means by any known part, attached to it according to known rules, to achieve a technical result, in respect of which the effect of such an addition is established;

- replacement of any part of a known product with another known part to achieve a technical result, in respect of which the effect of such a replacement is established;

- the exclusion of any part of the funds with the simultaneous exclusion of the function due to its presence and the achievement of the usual result for such exclusion;

- an increase in the number of elements of the same type, actions to enhance the technical result, due to the presence in the tool of just such elements, actions;

- the implementation of a known tool or part of a known material to achieve a technical result due to the known properties of this material;

- the creation of a tool consisting of known parts, the choice of which and the relationship between them are based on known rules, recommendations, and the technical result achieved in this case is due only to the known properties of the parts of this tool and the relationships between them.

The described invention is not based on a change in a quantitative characteristic (s), the presentation of such signs in relationship or a change in its form. This refers to the case when the fact of the influence of each of these characteristics on the technical result is known, and new values of these signs or their relationship could be obtained on the basis of known dependencies and patterns. Therefore, the claimed invention meets the condition of "inventive step".

The invention consists in the following. During cutting, cracking processes occur in the coating, leading to its destruction. In addition, due to insufficient adhesion to the tool base and layers inside the multilayer coating, the latter can be destroyed as a result of adhesion-fatigue phenomena on the contact pads. Under these conditions, the coating should have a layered structure to inhibit cracks. The bottom layer of the coating must have high adhesion to the tool material. The upper and lower layers of the coating must have high hardness to increase wear and crack resistance. Moreover, the layers of the multilayer coating should have high bond strength between each other, which is ensured by their high affinity for each other due to the presence of common elements.

Coated plates obtained with deviations from the indicated production technology showed lower results.

For experimental verification of the claimed method, a prototype coating was applied with a layer ratio corresponding to the optimal value specified in the known method, as well as a two-layer coating according to the proposed method. The coatings were applied to carbide plates in the vacuum chamber of the Bulat-6T installation, equipped with three vacuum-arc cathodes-evaporators located horizontally in the same plane.

The proposed coating is as follows. MK8 carbide inserts (4.7 × 12 × 12 mm in size) are washed in an ultrasonic bath, wiped with acetone, alcohol and mounted on a rotary device in the vacuum chamber of the Bulat-6 installation equipped with three evaporator cathodes located horizontally in the same plane. The first composite cathode of titanium and iron is used, the second composite cathode of titanium and aluminum, located opposite the first, and the third composite cathode of titanium and chromium, located between them. The chamber is pumped out to a pressure of 6.65 · 10 ^-3 Pa, the rotator is turned on, a negative voltage of 1.1 kV is applied to it, one cathode-evaporator is turned on, and at an arc current of 100 A, the plates are cleaned and heated to a temperature of 560-580 ° FROM. The focusing coil current is 0.4 A. Then, at a negative voltage of 160 V, a coil current of 0.3 A and a supply of reaction gas - nitrogen (or a mixture of nitrogen and acetylene), the first (from titanium and iron) and the third (from titanium and chromium) cathode-evaporators and precipitate the lower coating layer TiCrFeN (or TiCrFeCN) with a thickness of 2.5 μm. A 2.5 μm thick TiCrAlN (or TiCrAlCN) coating layer is applied at a negative voltage of 160 V, a current of 0.3 A coils included in the second (from titanium and aluminum) and third (from titanium and chromium) evaporator cathodes and the supply of reaction gas - nitrogen (or a mixture of nitrogen and acetylene). Then shut off the evaporators, the supply of reaction gas, voltage and rotation of the device. After 15-20 minutes, the chamber is opened and the coated tool is removed.

The microhardness of the coatings was determined on a PMT-3 microhardness meter under a load of 100 g.

The adhesion strength of the coating to the tool material was evaluated by pressing a diamond indenter on a TK-2M hardness tester with a load of 600 N. The criterion for assessing the adhesion-strength properties of the coating-tool material composition was the peeling coefficient, defined as the ratio of the peeling area of the coating to the indenter imprint area.

Table 1 Coated RI Test Results No pp Coating material The chemical composition of the coating layers (ratio of metal components),% wt. Peeling ratio Microhardness, GPa The thickness of the coating layers, microns Resistance, min Note 1 layer 2 layer 1 layer 2 layer Ti Cr Fe Ti Cr Al one 2 3 four 5 6 7 8 9 10 eleven 12 13 fourteen one TiN one hundred - 1.16 29.2 5 - 45 Analogue 2 TiSiN - TiSiZrN 98.9 1,1 - 76.8 1,0 22.2 1.48 37.6 2,5 2,5 144 Prototype 3 TiCrFeN - TiCrAlN 88.0 10.6 1.4 78 eleven eleven 1.21 38.1 2,5 2,5 152 - four TiCrFeN - TiCrAlN 88.4 10.6 1,0 76 eleven 13 1.30 38.9 2,5 2,5 175 - 5 TiCrFeN - TiCrAlN 88.0 10.6 1.4 76 eleven 13 1.21 39.5 2,5 2,5 181 - 6 TiCrFeN - TiCrAlN 87.4 10.6 2.0 76 eleven 13 1.28 38.5 2,5 2,5 171 - 7 TiCrFeN - TiCrAlN 88.0 10.6 1.4 74 eleven fifteen 1.21 37.9 2,5 2,5 162 - 8 TiCrFeCN - TiCrAlCN 88.0 10.6 1.4 75,5 10.5 fourteen 1.35 41.3 2,5 2,5 179 - 9 TiCrFeCN - TiCrAlCN 88.4 10.6 1,0 70.5 10.5 19 1,52 42.6 2,5 2,5 188 - 10 TiCrFeCN - TiCrAlCN 88.0 10.6 1.4 70.5 10.5 19 1.35 43,4 2,5 2,5 204 - eleven TiCrFeCN - TiCrAlCN 87.4 10.6 2.0 70.5 10.5 19 1,59 42.5 2,5 2,5 189 - 12 TiCrFeCN - TiCrAlCN 88.0 10.6 1.4 64.5 10.5 25 1.35 41.1 2,5 2,5 175 -

Durable tests of the cutting tool were carried out with the longitudinal turning of blanks made of 30KhGSA steel on a 16K20 lathe. Cutting modes: cutting speed V = 180 m / min, feed S = 0.15 mm / rev, cutting depth t = 0.5 mm, processing was performed without the use of coolant. Tested carbide inserts grade MK8, processed according to the known and proposed methods. The wear criterion was a chamfer of wear along the back surface with a width of 0.4 mm.

As can be seen from the data in table 1, the resistance of the plates processed by the proposed method is higher than the wear resistance of the plates processed by the prototype method by 1.26-1.42 times.

Thus, the above information indicates that when using the claimed method of obtaining a wear-resistant coating for RI the following set of conditions:

- a method for producing a multilayer coating for RI, embodying the claimed method in its implementation, is intended for use in industry, namely for applying wear-resistant coatings to RI, and can be used in metal processing;

- for the claimed method for producing a multilayer coating for RI in the form described in the independent clause of the claims, the possibility of its implementation using known means and methods prior to the priority date is confirmed;

- a method of obtaining a multilayer coating to obtain a wear-resistant coating for RI, embodying the claimed method in its implementation is capable of achieving the achievement of the technical result perceived by the applicant.

Therefore, the claimed invention meets the condition of "industrial applicability".

Claims (1)

A method of obtaining a multilayer coating for a cutting tool, comprising vacuum-plasma deposition of coating layers, characterized in that a lower layer of nitride or carbonitride of a compound of titanium, chromium and iron is applied at their ratio, wt.%: Titanium 87.2-88.7, chromium 10.0-11.2, iron 1.3-1.6, and the top layer is made of nitride or carbonitride of a compound of titanium, chromium and aluminum in their ratio, wt.%: titanium 75-77, chromium 10.4- 11.5, aluminum 12.6-13.5, while the deposition of layers is carried out horizontally in the same plane by three cathodes, the first of which which are made of titanium and iron, the second is made of titanium and aluminum and are opposite to the first, and the third is made of titanium and chromium and placed between them.