RU2461656C1 - Method of making multilayer coating for cutting tool - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: lower layer from nitride or carnonitride of titanium and aluminium is deposited at the ratio in wt %: titanium - 91.5-94.5 and aluminium - 5.5-8.5, while intermediate layer of said components is deposited at the ratio of, in wt %: titanium - 93.7-94.9, aluminium - 4.0-6.0, silicon - 1.1-1.3, and top layer is deposited at the ratio of, in wt %: titanium - 87.7-91.9, silicon - 7.0-11.0. Coating layers are applied by three cathodes arranged horizontally in one plane. First and second composite cathodes are made from titanium and aluminium are arranged opposite each other. Third composite cathode is made of titanium and silicon and arranged there between. Bottom layer is applied using first and second cathodes, intermediate layer is produced by first and second cathodes while top layer is made by second and third cathodes.

EFFECT: higher wear resistance.

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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 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 utility model RU 54039 U1, adopted as a prototype.

For reasons that impede the achievement of the technical result indicated below when using a known cutting tool with a coating adopted as a prototype, the multilayer coating in the known method has insufficient hardness and, therefore, crack resistance. As a result, the coating poorly resists the processes of wear and tear and quickly collapses when cutting.

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. Increasing the adhesion of the layers is achieved by applying an intermediate layer of elements of the upper and lower layers. This layer has a high chemical affinity with other layers, high hardness. The intermediate layer also contributes to increased crack resistance due to the appearance of additional boundaries between the layers.

The technical result is an increase in the health of RI.

The specified technical result during the implementation of the invention is achieved by applying a lower layer of nitride or carbonitride of the titanium and aluminum compounds at their ratio, wt.%: Titanium 91.5-94.5, aluminum 5.5-8.5; intermediate - from a nitride or carbonitride of a compound of titanium, aluminum and silicon at their ratio, wt.%: titanium 93.7-94.9, aluminum 4.0-6.0, silicon 1.1-1.3; the top - from nitride or carbonitride compounds of titanium, aluminum and silicon at their ratio, wt.%: titanium 87.7-91.9, aluminum 7.0-11.0, silicon 1.1-1.3, and coating coatings are carried out horizontally located in the same plane by three cathodes, the first and second of which are made of titanium and aluminum and are located opposite to each other, and the third is made of an alloy of titanium and silicon and placed between them, and the lower layer is applied using the first and second cathodes intermediate layer - using per of the second and third cathodes, the upper layer using the second and third cathodes.

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. Moreover, the layers have high hardness due to the additional alloying of the material of the coating layers and the presence in their structure of microlayers obtained by coating according to the proposed arrangement of the cathodes.

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. Coating layers 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 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 cathodes located horizontally in the same plane. The first and second composite cathodes of titanium and aluminum located opposite each other are used, and the third cathode is made of an alloy of titanium and silicon 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 is turned on, and at an arc current of 100 A, the plates are cleaned and heated to a temperature of 560-580 ° C. 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 aluminum) and the second (from titanium and aluminum) cathodes and deposit a 2.0 μm thick TiAlN (or TiAlCN) coating layer. The intermediate coating layer of TiAlSiN (or TiAlSiCN) with a thickness of 2.0 μm is applied at a negative voltage of 160 V, a current of coils of 0.3 A and the first (from titanium and aluminum) and third (from titanium and silicon) cathodes and a supply of reaction gas - nitrogen (or a mixture of nitrogen and acetylene). The upper coating layer of TiAlSiN (or TiAlSiCN) with a thickness of 2.0 μm is applied at a negative voltage of 160 V, a current of 0.3 A coils included by the second (from titanium and aluminum) and third (from titanium and silicon) 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 coating was determined on a PMT-3 microhardness meter under a load of 100 g.

Durable tests of the cutting tool were carried out with the longitudinal turning of billets 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.

Table 1 shows the test results of RI with the obtained coatings.

Table 1 Coated RI Test Results Coating material The chemical composition of the coating layers (ratio of metal components),% wt. Microhardness, GPa Resistance, min Note 1 layer 2 layer 3 layer Ti Al Ti Si Al Ti Si Al TiN - 29.2 45 Analogue TiAlN-TiAlSiN 93 7 - 89.8 1,2 9 38.8 149 Prototype TiAlN-TiAlSiN-TiAlSiN 94.5 5.5 94.8 1,2 four 91.8 1,2 7 39.1 188 93 7 93.9 1,1 5 89.9 1,1 9 39.5 197 93 7 93.8 1,2 5 89.8 1,2 9 39.7 210 93 7 93.7 1.3 5 89.7 1.3 9 39,4 205 91.5 8.5 92.8 1,2 6 87.8 1,2 eleven 39.0 196 TiAlCN-TiAlSiCN-TiAlSiCN 94.5 5.5 94.8 1,2 four 91.8 1,2 7 45,2 221 93 7 93.9 1,1 5 89.9 1,1 9 45.7 234 93 7 93.8 1,2 5 89.8 1,2 9 46.3 242 93 7 93.7 1.3 5 89.7 1.3 9 45.9 235 91.5 8.5 92.8 1,2 6 87.8 1,2 eleven 45.4 224

As can be seen from the data in table 1, the resistance of the plates with the coatings deposited by the proposed method is higher than the resistance of the plates with the coating deposited by the prototype method by 1.3-1.6 times.

Claims (1)

A method of obtaining a multilayer coating for a cutting tool, including vacuum-plasma deposition of a multilayer coating, characterized in that a lower layer of nitride or carbonitride of a titanium and aluminum compound is applied at their ratio, wt.%: Titanium 91.5-94.5, aluminum 5 5-8.5; intermediate - from a nitride or carbonitride of a compound of titanium, aluminum and silicon at their ratio, wt.%: titanium 93.7-94.9, aluminum 4.0-6.0, silicon 1.1-1.3; the top - from nitride or carbonitride compounds of titanium, aluminum and silicon at their ratio, wt.%: titanium 87.7-91.9, aluminum 7.0-11.0, silicon 1.1-1.3, and coating coatings are carried out horizontally located in the same plane by three cathodes, the first and second of which are made of titanium and aluminum and are located opposite to each other, and the third is made of an alloy of titanium and silicon and placed between them, and the lower layer is applied using the first and second cathodes intermediate layer - using per of the second and third cathodes, the upper layer using the second and third cathodes.