CN103255373B - A kind of TaVN compound coating and preparation method thereof - Google Patents

Abstract

The present invention relates to a kind of TaVN compound coating, it is characterized in that under the mixed gas atmosphere of nitrogen and argon gas, with metal, Wimet or pottery for matrix, adopt high-purity Ta target and high-purity V target co-sputtering, the atomic percent of V element is 0 ~ 46.7at% and is greater than 0, first at the pure Ta layer of deposition on substrate as transition layer, and then deposit the TaVN composite membrane of 1.5-2 μm.Gained TaVN film hardness is 30-34GPa, and the frictional coefficient under normal temperature is minimum is 0.56, and the frictional coefficient under high temperature is minimum is 0.5.Can be used as the coating of high speed cutting tool and other wear-resisting workpiece of being on active service under the high temperature conditions.

Description

A kind of TaVN composite coating and preparation method thereof

technical field

The invention relates to a thin film and a preparation method thereof, in particular to a TaVN composite coating with high hardness and low coefficient of friction, belonging to the technical field of ceramic coatings.

Background technique

In the manufacturing industry, one of the priorities is how to increase the efficiency of the machining process. Machining difficult-to-machine materials such as hard tool steels remains a challenge under extreme service conditions such as dry machining. The main feature of high-performance cutting is that the friction surface that reacts with the workpiece has high temperature and stress, and is susceptible to severe oxidation and erosion from the environment. In addition, during high-speed cutting, the temperature can rise to 800-1000 ° C. These harsh and extreme external conditions cause severe local plastic deformation, phase transformation, mass transfer, and chemical reactions on the frictional tool surface. These extreme working conditions lead to premature failure of cutting tools. Therefore, how to design a thin film material that can meet the extreme service conditions has always been the goal pursued by scholars from all over the world.

As a transitional metal nitride, TaN has a high melting point (3380°C) and a high hardness (1450HV). It is suitable for use as a wear-resistant material and can be used as an enhanced wear-resistant and anti-friction coating on the surface of tools and molds. However, in order to further improve the comprehensive properties of the TaN film surface, such as hardness, oxidation resistance and wear resistance, another transition metal is usually added to the raw material to form a multi-component film, such as TiCrN, TiZrN, and TaZrN.

According to the literature search of the prior art, it is found that the research on the TaN-based thin film is currently mainly focused on its electrical performance. After further searching of the prior art, no report identical or similar to the technical subject of the present invention has been found.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned problems in the prior art, and provide a TaVN composite coating with high hardness and low friction coefficient, which is suitable for high-speed cutting and dry cutting, and the preparation method is convenient and efficient.

The present invention is achieved through the following technical solutions:

TaVN composite coating is co-sputtered with Ta target (purity 99.9%) and V target (purity 99.9%), deposited on metal, hard alloy or ceramic substrate, and the thickness of TaVN film layer is 1-3μm. The coating has a hardness of 30-34GPa, a minimum friction coefficient of 0.56 at normal temperature, and a minimum of 0.5 at high temperature.

Among them, the atomic percentage of V element is 0-46.7 at%, combined with the hardness and friction coefficient, the more optimal range is 18.25-46.7 at%, and the more preferable range is 18.25-32.8 at%.

The TaVN composite coating provided by the present invention can be prepared by a reactive sputtering method, specifically _: metal Ta and V are sputtered by radio frequency cathodes using reactive magnetron sputtering technology, and mixed with Ar gas and N gas in a vacuum chamber The N ₂ gas reacts to generate TaVN. By adjusting the sputtering power added to the V target, TaVN films with different V contents are prepared, which is easy to control the content of each component in the coating and facilitates the preparation of the coating.

Specifically:

(1) Use metal, cemented carbide or ceramics as the substrate, wash, ultrasonicate, and dry it and then fix it on the rotatable substrate holder in the vacuum chamber;

(2) Install the high-purity Ta target and V target on two RF sputtering guns respectively;

(3) The vacuum chamber is evacuated, and the mixed gas of high purity Ar and N ₂ is introduced into the vacuum chamber, wherein the partial pressure of argon is (0.5-1.5)×10 ^-1 Pa, and the partial pressure of nitrogen is (2-4 )×10 ^-2 Pa, the working pressure is kept at 0.3Pa;

(4) The Ta target power is fixed at 100W, and the V target power is 40-100W respectively. Firstly, a pure Ta layer is deposited on the substrate as a transition layer, and then a 1-3 μm TaVN composite film is deposited.

The obtained TaVN composite coating has properties of both high hardness and low friction coefficient, and has great application value for tool protection coatings for high-speed cutting and dry cutting and other wear-resistant coatings in industrial production.

Description of drawings

Figure 1 is the relationship diagram between the microstructure and V content of the TaVN composite film of the present invention; a single TaN film has a δ-NaCl face-centered cubic structure, and the (200) plane is preferred. The TaVN film has a face-centered cubic structure similar to that of a single-layer TaN film. With the increase of the V content, each diffraction peak shifts to a large angle as a whole, and the preferred orientation gradually changes from (200) to (111);

Fig. 2 is the relationship diagram of hardness and V content of TaVN composite film of the present invention; The hardness of the TaVN composite film formed after adding V element is all higher than single-layer TaN film, and the lattice distortion that solid solution strengthening produces is that TaVN composite film microscopic Reasons for increased hardness;

Fig. 3 is a graph showing the relationship between the average friction coefficient and the V content of the TaVN composite film of the present invention at room temperature. It can be seen that the friction coefficient of TaVN composite film decreases with the increase of V content at room temperature;

Fig. 4 is a graph showing the relationship between the average coefficient of friction and the experimental temperature of a composite film with a V content of 18.25 at% in the TaVN composite film of the present invention. It can be seen that above 400 °C, as the temperature increases, the friction coefficient of the composite film also decreases. The main reason is that the self-lubricating Magnéli phase V ₂ O ₅ is formed in the friction contact.

Detailed ways

Thin films were prepared by JGP-450 multi-target magnetron sputtering apparatus, and TaVN composite thin films were deposited on single crystal silicon wafers and stainless steel substrates. The Ta target (99.9% purity) and the V target (99.9% purity) were installed on two RF sputtering guns respectively, and the distance between the substrate holder and the sputtering gun was 78 mm. After the substrate is ultrasonically cleaned with acetone and absolute alcohol, it is quickly dried and placed on a rotatable substrate holder in a vacuum chamber. The background vacuum of the vacuum chamber is better than 6×10 ^-4 Pa. A mixed gas of Ar and N ₂ with a purity of 99.999% was introduced into the vacuum chamber, wherein the partial pressure of argon was 1×10 ^-1 Pa, the partial pressure of nitrogen was 3×10 ^-2 Pa, and the working pressure was kept at 0.3Pa. In the process of preparing TaVN thin films, the Ta target power was fixed at 100W, and the V target power was 40, 70 and 100W, respectively, so as to prepare a series of TaVN composite films with different V contents. Before preparing the TaN single-layer film and TaVN composite film, pre-deposit about 100nm of pure Ta on the substrate as a transition layer, and then deposit about 1-3 μm of TaN single-layer film and TaVN composite film.

The TaVN composite coating provided by the present invention can be prepared by reactive physical vapor deposition in Ar and N ₂ mixed gases. For example, the two targets (respectively Ta target and V target) are prepared by reactive sputtering.

Implementation examples are provided below in conjunction with the contents of the present invention:

Example one

The Ta target power is 100W, the V target power is 0W, and a TaN single coating is prepared.

The reactive magnetron sputtering technology is used to sputter metal Ta through radio frequency cathode, and react with the N ₂ gas in the mixed gas of Ar gas and N ₂ gas in the vacuum chamber to form a Ta-N coating. The hardness of the coating is 27.8GPa, the thickness is 1-3μm, the friction coefficient at room temperature is 0.66, the friction coefficient at 600°C is 0.8, and the friction coefficient at 800°C is 0.7.

Example two

The Ta target power is 100W, the V target power is 40W, and the Ta _0.82 V _0.18 N composite coating is prepared.

TaVN composite coatings were formed by reactive magnetron sputtering technology through radio frequency cathode sputtering metal Ta and V, and reacted with N ₂ gas in the mixed gas of Ar gas and N ₂ gas in the vacuum chamber. The hardness of the coating is 32.305GPa, the thickness is 1-3μm, the friction coefficient at room temperature is 0.64, the friction coefficient at 600°C is 0.65, and the friction coefficient at 800°C is 0.5.

Example three

The Ta target power is 100W, the V target power is 70W, and the Ta _0.67 V _0.33 N composite coating is prepared.

TaVN composite coatings were formed by reactive magnetron sputtering technology through radio frequency cathode sputtering metal Ta and V, and reacted with N ₂ gas in the mixed gas of Ar gas and N ₂ gas in the vacuum chamber. The hardness of the coating is 30.215GPa, the thickness is 1-3μm, the friction coefficient at room temperature is 0.58, and the friction coefficient at 800°C is 0.56.

Example four

The Ta target power is 100W, the V target power is 100W, and the Ta _0.53 V _0.47 N composite coating is prepared.

TaVN composite coatings were formed by reactive magnetron sputtering technology through radio frequency cathode sputtering metal Ta and V, and reacted with N ₂ gas in the mixed gas of Ar gas and N ₂ gas in the vacuum chamber. The hardness of the coating is 29.472GPa, the thickness is 1-3μm, the friction coefficient at room temperature is 0.56, and the friction coefficient at 800°C is 0.51.

According to the practice of the inventors, in the mixed gas of argon and nitrogen, the partial pressure of argon is in the range of (0.5-1.5)×10 ^-1 Pa, and the partial pressure of nitrogen is in the range of (2-4)×10 ^-2 Pa. At 0.3Pa, the above-mentioned experimental process can be realized, and the thickness of the obtained TaVN film is 1-3μm, the hardness is 30-34GPa, the friction coefficient at room temperature is at least 0.56, and the friction coefficient at high temperature is at least 0.5.

Claims (2)

1.TaVN compound coating, it is characterized in that adopting high-purity Ta target and high-purity V target co-sputtering, the matrix being deposited on metal, Wimet or pottery obtains, the thickness of TaVN rete is 1-3 μm, hardness is 30-34GPa, frictional coefficient under normal temperature is minimum is 0.56, and the frictional coefficient under high temperature is minimum is 0.5; Wherein the atomic percent of V element is 18.25 ~ 32.8at%; The purity of high-purity Ta target and high-purity V target is 99.9%.

2. the preparation method of TaVN compound coating according to claim 1, it is characterized in that adopting reaction magnetocontrol sputtering technology by radio frequency cathode sputtering metal Ta and V, and with Ar gas and N in vacuum chamber ₂n in mixed gas ₂solid/liquid/gas reactions generates TaVN, by regulating the sputtering power being added in V target, prepares the TaVN film of different V content.