CN106756785A - Multi-element composite nano hard coating and preparation method thereof - Google Patents

Abstract

The invention relates to a multi-component composite nano-hard coating for the surface of a cutting tool, the coating comprises at least two layers of CrN and CrTiBN, wherein the atomic percentage of Cr and N in the CrN layer is 60:40 to 70:30, The percentages of each atom in the CrTiBN layer are Cr 10-25%, Ti 8-30%, B 14-29%, and N 30-60%. According to the present invention, the B element in the coating has the effect of refining grains, which greatly improves the hardness of the coating, and also has a certain effect on the improvement of the high temperature oxidation resistance and chemical reactivity of the coating, which can effectively prolong the life of the tool. service life.

Description

A kind of multi-component composite nano hard coating and preparation method thereof

technical field

The invention belongs to the technical field of metal surface coatings, and in particular relates to the preparation of a multi-component composite structure nano hard coating by adopting a physical vapor deposition (PVD) technology.

Background technique

Vapor deposition technology mainly includes CVD (chemical vapor deposition) and PVD (physical vapor deposition), which is the most active research field in contemporary vacuum technology and material science, and is also the mainstream direction of tool surface coating technology. It can not only be used to prepare Film coatings with various special properties, and can also be used to prepare various functional film materials and decorative film coatings, and to deposit various compounds, non-metals, semiconductors, ceramics, plastic films, etc. Compared with CVD technology, PVD technology has a higher deposition temperature; faster deposition rate; the deposited coating has a fine structure and strong crack resistance; the coating surface is smooth and the friction coefficient is low; the coating is prepared under vacuum conditions. The concept of green manufacturing. At present, PVD coating has been extended to aerospace, mechanical processing, electronic communication, medical equipment, home appliances and other industries. Coatings and nano coatings, etc.

Single-layer coatings have been used in the first ten years of the development of vapor deposition technology. Typical representatives include TiC, TiN, Al ₂ O ₃ , CrN, and others include NbC, HfC, ZrC, ZrN, BN, etc. Among them, CrN coating is currently the most widely used, and is known as one of the materials that can best replace TiN coating, and because of its excellent wear resistance, it is mainly used for molds such as plastic films and cold heading punches, and according to its good performance Anti-caking and chemical stability cutting soft materials such as titanium alloy, titanium, copper, aluminum and so on.

Compared with single-layer coating, multi-layer coating can effectively inhibit the growth of coarse grain structure, improve the coating structure, give full play to the advantages of different coating materials in each layer, and effectively improve product performance. The most commonly used multilayer coating is a combination of two coatings or a multilayer composite coating with 3 to 7 layers.

The multi-component composite coating is to add elements such as Cr, Zr, V, B, Hf and so on to the single-layer coating and multi-layer coating, which can improve the oxidation resistance and wear resistance, and greatly improve the relationship between the coating and the substrate. combination. At present, TiCN and TiAlN are the most commonly used, and there are TiSiN, TiBN, TiAlSi, TiAlCN and so on.

Therefore, the gradient coating is to perform gradient treatment on the surface of the substrate, so that a certain depth area on the surface of the coating substrate forms a tough zone of carbides and carbonitrides. The binder content in this area is generally higher than the nominal bond of the coating substrate. When the crack extends to this area, due to the excellent toughness of this tough zone, it will effectively absorb the energy of crack expansion and improve the service life of the tool.

Nano-coatings have attracted extensive attention of researchers since their appearance due to their characteristics of high hardness, high heat resistance, relatively high toughness, and long service life under the premise of low cost and green processing. It is mainly divided into two types of nano-multilayer structure and nano-composite structure coating.

Contents of the invention

The object of the present invention is to provide a kind of multi-component composite nano hard coating for cutting tool surface, said coating comprises at least two layers of CrN and CrTiBN, wherein the atomic percentage of Cr and N of CrN layer is 60:40 to 70: 30, preferably 67:33, the percentage of each atom in the CrTiBN layer is Cr 10-25%, Ti 8-30%, B 14-29%, N 30-60%, preferably Cr20%, Ti19%, B19% and N42%.

Preferably, the coating comprises multiple layers of CrN and CrTiBN, preferably 2-200 layers, preferably 4-50 layers, more preferably 2 to 4 layers, the CrN layers and CrTiBN layers are arranged alternately, preferably the innermost layer is a CrN layer, and the outermost layer is a CrTiBN layer.

Preferably, the thickness of the CrN layer in the coating is 0.3-0.35 μm and the thickness of the CrTiBN layer is 2.5-3 μm, further preferably, the thickness of the CrN layer is 0.33 μm and the thickness of the CrTiBN layer is 2.8 μm.

Preferably, the total thickness of the coating including the CrN layer and the CrTiBN layer is about 3-8 μm.

The method for preparing the coating including the CrN layer and the CrTiBN layer according to the present invention is not particularly limited, and the layers can be prepared by conventional PVD deposition methods in the art. Preferably, it can be prepared according to the following method:

Another object of the present invention is to provide a kind of preparation method of described multi-component composite nano-hard coating, and described preparation method comprises the following steps:

Step 1) Substrate pre-treatment: put the substrate into the ultrasonic tank of the cleaning line to perform degreasing, rust removal and other processes in turn, and perform rough cleaning; then perform sandblasting on the substrate after rough cleaning; finally put the substrate into the cleaning The wires were ultrasonically cleaned and dried for 30 minutes.

Step 2) Fix the substrate on the turntable and rotate it in a 3-dimensional manner. When the vacuum degree of the furnace chamber reaches 8.0×10 ^-3 Pa and the temperature reaches 400° C., PVD coating treatment starts.

Step 3) Open the Cr target for Cr bombing after 40 minutes of argon glow; 30 minutes later, nitrogen gas is injected for CrN layer deposition, the coating time is 10 to 20 minutes, and the expected thickness is 0.3 to 0.35 μm.

Step 4) Open the Ti target for 5 minutes, then open the B target and keep the Cr target open, and deposit a CrTiBN layer for 40 to 60 minutes, with an expected thickness of 2.5-3 μm.

Preferably, the step 3) and step 4) can be alternately performed multiple times to alternately form multiple layers of CrN layers and CrTiBN layers.

The process parameters of the step 3) are: vacuum degree 1.5Pa, argon input volume 20-25, nitrogen input volume 240-250, bias voltage 150V, temperature 380°C.

Step 4) The process parameters are: vacuum degree 1.6Pa, argon input volume 7-10, nitrogen input volume 260-270, bias voltage 110V, temperature 380°C.

Beneficial effect

(1) The B element in the coating has the effect of refining grains, greatly improving the hardness of the coating, and also has a certain effect on improving the high temperature oxidation resistance and chemical reactivity of the coating.

(2) The content of Cr and N elements in the coating is relatively high, which greatly improves the high temperature oxidation resistance of the coating.

(3) The coating surface contains Ti and B elements, which effectively reduces the friction coefficient of the coating surface and improves wear resistance.

(4) The coating adopts CrN primer and multi-layer structure distribution, which reduces the internal stress of the coating and the expansion of internal cracks in the coating, improves the bonding force of the film base, and increases the service life of the coating product.

The coating comprising the CrN layer and the CrTiBN layer according to the present invention effectively solves the problem of harsh processing conditions of high-speed dry cutting tools and hot-working molds, and prolongs the service life of the tools.

Description of drawings

Figure 1 is a schematic diagram of the 4-layer structure of CrN/CrTiBN multi-component composite nano-hard coating

Figure 2 is a flow chart of the preparation process of CrN/CrTiBN multi-component composite nano hard coating

Fig. 3 is the appearance of the CrN/CrTiBN coating product of the gear hob in embodiment 1

Fig. 4 is the appearance of the CrN/CrTiBN coating product of the aluminum die-casting mold of embodiment 2

detailed description

According to the present invention, the CrN layer in the coating is a transition layer, which can improve the bonding force of the film base; the internal stress of the CrTiBN layer is small, and the crack growth resistance is strong; and the surface of the coating contains B elements, which can effectively reduce the friction coefficient and improve Friction and wear resistance of the coating.

In the coating comprising the CrN layer and the CrTiBN layer according to the present invention, the B element is introduced into the CrTiBN layer, and the atomic percentage of the B element is controlled within the range of 14-29%, preferably 19%. The inventors of the invention found that when the B element is introduced into the layer and the atomic percentage of the B element is controlled within the above range, the hardness and oxidation resistance temperature of the coating can be significantly improved. When the atomic percentage of the B element is within the above range, the coating hardness and oxidation resistance temperature cannot be improved.

Hereinafter, the present invention will be described in detail. Before proceeding with the description, it should be understood that the terms used in this specification and appended claims should not be construed as limited to ordinary and dictionary meanings, but should be best interpreted while allowing the inventor to properly define the terms On the basis of the principles of the present invention, explanations are made based on meanings and concepts corresponding to the technical aspects of the present invention. Accordingly, the descriptions set forth herein are preferred examples for illustrative purposes only and are not intended to limit the scope of the invention, so that it should be understood that other, etc. price or improvement.

Before the description, it should be understood that the terms used in the specification and appended claims should not be construed as limited to the general and dictionary meanings, but should be based on the principle of allowing the inventor to define the terms appropriately for the best interpretation, based on the corresponding Explain the meaning and concept on the technical level of the present invention. Therefore, the description herein is only a preferred example for the purpose of illustration, not intended to limit the scope of the present invention, so it should be understood that other equivalent implementations and modifications can be made without departing from the spirit and scope of the present invention. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products.

Embodiment 1: Preparation of CrN/CrTiBN hard coating on the surface of gear hob

The base material of the hob is used for machining external spur gears and helical spur gears.

Step 1) Substrate pre-treatment: put the hob into the ultrasonic tank of the cleaning line to perform degreasing, rust removal and other processes in turn, and perform rough cleaning; then deburr the hob after rough cleaning, and perform sandblasting after completion ;Finally put the hobbing cutter into the cleaning line for ultrasonic fine cleaning, and dry for 30min.

Step 2) Fix the hobbing cutter on the turntable and rotate it in a 3-dimensional manner. When the vacuum degree of the furnace chamber reaches 8.0×10 ^-3 Pa and the temperature reaches 400° C., PVD coating treatment starts.

Step 3) Open the Cr target for Cr bombing after 40 minutes of argon glow; 30 minutes after passing nitrogen gas for CrN layer deposition, the coating time is 15 minutes, and the thickness is 0.33 μm.

Step 4) Open the Ti target for 5 minutes, then open the B target and keep the Cr target open, deposit a CrTiBN layer for 45 minutes, with an estimated thickness of 2.8 μm.

The process parameters of the step 3) are: process parameters are: vacuum degree 1.5Pa, argon input volume 20-25, nitrogen input volume 240-250, bias voltage 150V; step 4) process parameters are: vacuum degree 1.6Pa, argon The gas input volume is 7-10, the nitrogen gas input volume is 260-270, the bias voltage is 110V, and the temperature is 380°C.

The obtained coating has a hardness of 65.7 GPa and a coating thickness of 3.13 μm. Under the cutting operation condition of 1000℃, the service life of the gear hobbing cutter is increased by 4.17 times.

Embodiment 2: Preparation of CrN/CrTiBN hard coating on the surface of aluminum die-casting mold

The base material is aluminum die-casting mold, the mold base material H13 is steel, after heat treatment and ion nitriding, the working temperature is 600°C.

Except that steps 3) and 4) were repeated once in order, a CrN/CrTiBN hard coating was formed on the surface of the aluminum die-casting mold in the same manner as in Example 1.

The obtained coating has a hardness of 63.1 GPa and a coating thickness of 6.5 μm.

Comparative Example 1

Only a CrN coating was formed on the surface of the hob in the same manner as in Example 1 except that no CrTiBN layer was formed. The hardness of the obtained coating is 35.2GPa, and the service life of the gear hob is increased by 1.32 times under the cutting operation condition of 1000°C.

Comparative Example 2

Only a CrTiBN coating was formed on the surface of the hob in the same manner as in Example 1 except that no CrN layer was formed. The hardness of the obtained coating is 40.2GPa, and the service life of the gear hob is increased by 1.89 times under the cutting operation condition of 1000°C.

Comparative Example 3

According to the method described in the prior art CN105839054A, a CrAlTiSiN coating is formed on the surface of the gear hob, and the thickness of the coating is 3.5 μm. The hardness of the obtained coating is 40.8GPa, and the service life of the gear hob is increased by 2.37 times under the cutting operation condition of 1000°C.

From the experimental data of Examples 1 and 2 and Comparative Examples 1 to 3, it can be seen that the coating containing the CrN/CrTiBN layer of the present invention can effectively improve the hardness of the product and significantly increase the service life of the product.

Claims (10)

1. A multi-component composite nano-hard coating for cutting tool surface, said coating comprises at least two layers of CrN and CrTiBN, wherein the atomic percentage of Cr and N of the CrN layer is 60:40 to 70:30, CrTiBN The percentage of each atom in the layer is Cr 10-25%, Ti 8-30%, B 14-29%, N 30-60%. 2. multivariate composite nano-hard coating according to claim 1, is characterized in that, the Cr of described CrN layer and the atomic percentage of N are 67:36, and the percentage of each atom is Cr20%, Ti19% in the CrTiBN layer , B19% and N42%. 3. The multi-component composite nano hard coating according to claim 1, characterized in that the coating comprises 2-200 layers of CrN and CrTiBN layers, preferably 4-50 layers, more preferably 2-4 layers. 4. The multi-component composite nano-hard coating according to claim 1, characterized in that the CrN layers and CrTiBN layers are arranged alternately. 5. The multi-component composite nano-hard coating according to claim 1, wherein the innermost layer is a CrN layer, and the outermost layer is a CrTiBN layer. 6. The multi-component composite nano-hard coating according to claim 1, characterized in that the thickness of the CrN layer in the coating is 0.3-0.35 μm and the thickness of the CrTiBN layer is 2.5-3 μm. 7. The multi-component composite nano hard coating according to claim 1, characterized in that the thickness of the CrN layer is 0.33 μm and the thickness of the CrTiBN layer is 2.8 μm. 8. The multi-component composite nano hard coating according to claim 1, characterized in that the total thickness of the coating including the CrN layer and the CrTiBN layer is about 3-8 μm. 9. A preparation method of multi-component composite nano-hard coating, said preparation method comprising the following steps: Step 1) Substrate pretreatment: put the substrate into the ultrasonic tank of the cleaning line to perform degreasing, rust removal and other processes in sequence, and perform rough cleaning; then deburr the substrate after rough cleaning, and perform sandblasting after completion; finally Put the substrate into the cleaning line for ultrasonic fine cleaning, and dry for 30 minutes; Step 2) Fix the substrate on the turret, rotate it in a 3-dimensional manner, and start the PVD coating process when the vacuum degree of the furnace chamber reaches 8.0×10 ^-3 Pa and the temperature reaches 400°C; Step 3) After 40 minutes of argon glow, open the Cr target for Cr bombardment; after 30 minutes, nitrogen gas is injected to deposit the CrN layer, the coating time is 10 to 20 minutes, and the expected thickness is 0.3 to 0.35 μm; Step 4) Open the Ti target for 5 minutes, then open the B target and keep the Cr target open, and deposit a CrTiBN layer for 40 to 60 minutes, with an expected thickness of 2.5-3 μm. 10. The preparation method according to claim 9, characterized in that, the step 3) and step 4) can be alternately performed multiple times to alternately form multiple layers of CrN layers and CrTiBN layers; The process parameters of the step 3) are: vacuum degree 1.5Pa, argon input volume 20-25, nitrogen input volume 240-250, bias voltage 150V, temperature 380°C; Step 4) The process parameters are: vacuum degree 1.6Pa, argon input volume 7-10, nitrogen input volume 260-270, bias voltage 110V, temperature 380°C.