阅读说明：本技术 一种提高AlCrSiN/Mo纳米复合涂层韧性与耐磨性的热处理工艺 (Heat treatment process for improving toughness and wear resistance of AlCrSiN/Mo nano composite coating ) 是由 王铁钢 朱强 蒙德强 刘艳梅 阎兵 范其香 于 2020-04-15 设计创作，主要内容包括：本发明公开了一种提高AlCrSiN/Mo纳米复合涂层韧性与耐磨性的热处理工艺,属于涂层技术领域。该工艺采用真空管式炉对由高功率脉冲磁控溅射结合脉冲直流磁控溅射复合镀膜技术沉积的AlCrSiN/Mo复合涂层进行加热处理。加热之前,将真空度抽至3×10<Sup>-3</Sup>Pa以下,按照预先的温度设定,对涂层进行相应的加热处理并获得所述热处理后的AlCrSiN/Mo纳米复合涂层。本发明涉及的复合涂层处理工艺简单,并且容易工业化生产。本发明制备的AlCrSiN/Mo复合涂层具有良好的韧性及润滑性能,可以显著增强基体的抗磨损能力,具有较好的化学稳定性。(The invention discloses a heat treatment process for improving toughness and wear resistance of an AlCrSiN/Mo nano composite coating, which belongs to the technical field of coatings and adopts a vacuum tube furnace to heat an AlCrSiN/Mo composite coating deposited by a high-power pulse magnetron sputtering and pulse direct-current magnetron sputtering composite coating technology, wherein before heating, the vacuum degree is pumped to 3 × 10 ‑3 And (4) below Pa, performing corresponding heating treatment on the coating according to the preset temperature setting, and obtaining the AlCrSiN/Mo nano composite coating after the heat treatment. The composite coating treatment process provided by the invention is simple and is easy for industrial production. The AlCrSiN/Mo composite coating prepared by the method has good toughness and lubricating property, can obviously enhance the abrasion resistance of a matrix, and has good chemical stability.)

1. A heat treatment process for improving toughness and wear resistance of an AlCrSiN/Mo nano composite coating is characterized by comprising the following steps of: the process adopts a vacuum tube furnace to carry out heat treatment on the AlCrSiN/Mo nano composite coating, and improves the toughness and the wear resistance of the AlCrSiN/Mo nano composite coating by controlling the heating rate, the heat preservation time and the cooling rate of different heat treatment stages.

2. The heat treatment process for improving the toughness and the wear resistance of the AlCrSiN/Mo nano composite coating according to claim 1, wherein: the heat treatment process comprises the following steps:

(1) fixing the coating sample with AlCrSiN/Mo nano composite coating in a ceramic crucible, placing the ceramic crucible in a vacuum tube of a tube furnace, and vacuumizing to make the vacuum degree in the tube less than 3 × 10^-3Pa；

(2) Carrying out heat treatment on the coating sample, wherein the heat treatment process comprises the following steps: heating to a temperature T at a heating rate of 5-15 ℃/min, wherein the temperature T is 750 ℃ after 550 ℃, and then carrying out heat preservation for 50-80 min; and then cooling to room temperature according to the cooling rate of 3-6 ℃/min, and taking out the sample.

3. The heat treatment process for improving the toughness and the wear resistance of the AlCrSiN/Mo nano composite coating according to claim 2, wherein: in the step (2), the temperature rise process specifically comprises: firstly, heating to the temperature T according to the heating rate of 7 ℃/min₁，T₁(T-90 ℃ C.) to (T-110 ℃ C.); then the temperature is raised to the temperature T at the temperature rise rate of 10 ℃/min₂，T₂(T-20 ℃ C.) - (T-50 ℃ C.); finally, the temperature is increased to the temperature T at the temperature increase rate of 8 ℃/min.

4. The heat treatment process for improving the toughness and the wear resistance of the AlCrSiN/Mo nano composite coating according to claim 2, wherein: the substrate of the coating sample is a monocrystalline silicon wafer, a high-temperature alloy or a hard alloy end mill.

5. The heat treatment process for improving the toughness and the wear resistance of the AlCrSiN/Mo nano composite coating according to claim 2, wherein: after the coating sample is subjected to heat treatment, the AlCrSiN/Mo nano composite coating consists of AlN nanocrystalline phase, CrN nanocrystalline phase and Mo₂N nanocrystalline phase and Si₃N₄The amorphous phase forms a nanocomposite structure.

6. The heat treatment process for improving the toughness and the wear resistance of the AlCrSiN/Mo nano composite coating according to claim 1, wherein: the AlCrSiN/Mo nano composite coating comprises the following chemical components in atomic percentage: 14.75-16.71 at.% of Al, 29.49-33.19 at.% of Cr, 42.22-48.42 at.% of N, 1.91-7.96 at.% of Si, and 5.0-6.33 at.% of Mo.

Technical Field

The invention relates to the technical field of coatings, in particular to a heat treatment process for improving toughness and wear resistance of an AlCrSiN/Mo nano composite coating.

Background

PVD is one of the effective methods for improving the surface properties of materials and plays an important role in industrial applications, especially in machining. CrN as oneThe hard protective coating is widely applied, and with the continuous improvement of cutting speed and cutting temperature, the CrN coating cutter gradually shows the defects of lower hardness, poor oxidation resistance, poor binding force and the like, and the cutter can rapidly lose efficacy due to high-temperature oxidation and severe abrasion of the surface. The AlCrN coating can be formed by adding Al into the CrN coating, and a compact (Al, Cr) layer can be formed on the surface of a cutter during cutting₂O₃The mixed oxide layer prevents the internal coating and the cutter substrate from being further oxidized, improves the wear resistance and the heat resistance of the coated cutter, obviously improves the processing efficiency of cutting and forming tools, prolongs the service life, and is widely applied in the market.

With the rapid development of the machining industry, the requirements on the machining efficiency and the machining precision are higher and higher, the machining requirements on difficult-to-cut materials such as quenched steel, titanium alloy and the like are increased rapidly, and the cutting performance of the tool coating is continuously provided with harsh requirements. The AlCrN coating is easy to oxidize and become brittle at high temperature, and the heat resistance and the mechanical property of the coating can be further improved by doping alloy elements to prepare the AlCrXN coating (X is Si, Zr, Nb, Ta, Hf and the like). For example, Si element is doped into the AlCrN coating, the prepared AlCrSiN coating has good mechanical property and oxidation resistance, amorphous phase SiNx is easily generated after the Si element is added, a nano composite structure is formed, and the fine grain strengthening effect is achieved. In addition, Si element is added, and the alloy also has high temperature oxidation resistance, on one hand, interface phase Si₃N₄Can slow down the decomposition of the nano-crystal and on the other hand can make the amorphous compound Si₃N₄Will oxidize at high temperature to form SiO₂Can block the diffusion of oxygen element at high temperature. In addition, the nanocrystalline has higher hardness, good plasticity of the amorphous phase and high cohesive energy of a two-phase interface, and the crystalline phase and the amorphous phase are separated in thermodynamics; dislocation can not be formed in the fine nano-crystal, a thin amorphous layer between crystal grains can effectively prevent the sliding of crystal boundary, and a large number of two-phase interfaces increase the expansion resistance of micro-crack. Therefore, the structural coating has high hardness, high toughness, excellent wear resistance and high-temperature thermal stability, and is suitable for working conditions such as high-speed cutting, dry processing and the like. A great deal of research shows that the sixth subgroup Mo element can significantly improve the tribological performance becauseMo is easy to oxidize to generate MoO with low shear modulus₃The lubricating oil acts as a solid lubricating phase during cutting machining, and is beneficial to reducing the friction force between the cutter and a workpiece and between the cutter and chips.

Related researches show that the temperature rise can intensify the diffusion of atoms in the coating and promote the conversion from amorphous to nanocrystalline, so that the coating is strengthened, and the comprehensive performance of the coating is expected to be further improved by optimizing the heat treatment temperature. Therefore, the invention adopts the vacuum tube furnace to carry out vacuum heat treatment on the AlCrSiN/Mo nano composite coating prepared by the high-power pulse magnetron sputtering and pulse direct current magnetron sputtering composite coating technology so as to improve the phase structure and the density of the coating and improve the wear resistance, the oxidation resistance and the cutting performance of the coating.

Disclosure of Invention

The invention aims to provide a heat treatment process for improving the toughness and the wear resistance of an AlCrSiN/Mo nano composite coating, and H/E and H of the AlCrSiN/Mo nano composite coating after heat treatment³/E*²The wear-resistant material has a high value, can remarkably enhance the wear-resistant performance of the matrix material, and has good toughness and chemical stability.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a heat treatment process for improving the toughness and wear resistance of AlCrSiN/Mo nano composite coating is characterized in that a vacuum tube furnace is adopted to carry out heat treatment on a coating sample deposited with the AlCrSiN/Mo nano composite coating, and the toughness and wear resistance of the AlCrSiN/Mo nano composite coating are improved by controlling the heating rate, the heat preservation time and the cooling rate in different heat treatment stages.

The heat treatment process comprises the following steps:

(1) fixing the coating sample with AlCrSiN/Mo nano composite coating in a ceramic crucible, placing the ceramic crucible in a vacuum tube of a tube furnace, and vacuumizing to make the vacuum degree in the tube less than 3 × 10^-3Pa；

(2) Carrying out heat treatment on the coating sample, wherein the heat treatment process comprises the following steps: heating to a temperature T at a heating rate of 5-15 ℃/min, wherein the temperature T is 550-; and then cooling to room temperature according to the cooling rate of 3-6 ℃/min, and taking out the sample.

In the step (2), the temperature raising process specifically includes: firstly, heating to the temperature T according to the heating rate of 7 ℃/min₁，T₁(T-90 ℃ C.) to (T-110 ℃ C.); then the temperature is raised to the temperature T at the temperature rise rate of 10 ℃/min₂，T₂(T-20 ℃ C.) - (T-50 ℃ C.); finally, the temperature is increased to the temperature T at the temperature increase rate of 8 ℃/min.

The substrate of the coating sample is a monocrystalline silicon wafer, a high-temperature alloy or a hard alloy cutter.

After the coating sample is subjected to heat treatment by adopting the method, the obtained AlCrSiN/Mo nano composite coating consists of AlN nanocrystalline phase, CrN nanocrystalline phase and Mo nanocrystalline phase₂N nanocrystalline phase and Si₃N₄The amorphous phase forms a nanocomposite structure.

The AlCrSiN/Mo nano composite coating comprises the following chemical components in atomic percentage: 14.75-16.71 at.% of Al, 29.49-33.19 at.% of Cr, 42.22-48.42 at.% of N, 1.91-7.96 at.% of Si, and 5.0-6.33 at.% of Mo.

The design mechanism of the invention is as follows:

the invention adopts a vacuum tube furnace to carry out heat treatment on the AlCrSiN/Mo nano composite coating deposited by adopting the high-power pulse magnetron sputtering and pulse direct-current magnetron sputtering composite coating technology, promotes the crystallization of the coating and improves the performance. The temperature rise can effectively enhance the diffusion capacity of atoms in the coating, and the invention reduces the defects of original vacancies, holes and the like in the coating by controlling the heating rate, the heat preservation time, the cooling rate and the like in the heat treatment process of the coating, improves the phase structure of the coating and improves the density of the coating. Due to the existence of silicon nitride in the coating, different temperature rise rates are preferably selected in different temperature intervals, the microstructure of the AlCrSiN/Mo nano composite coating is regulated and controlled by optimizing the heat treatment temperature, the cutter is endowed with good toughness and wear resistance, the cutter is suitable for high-speed dry cutting working conditions, and the service life and the processing efficiency of the cutter are further improved.

The invention selects the vacuum tube furnace to carry out heat treatment on the AlCrSiN/Mo nano composite coating, has the advantages of no oxidation, no decarburization and the like, and can effectively adjust the internal stress of the coating, improve the phase structure of the coating and lead the service performance.

The invention has the following advantages and beneficial effects:

1. the AlCrSiN/Mo nano composite coating after heat treatment has the advantages of high hardness, good toughness and the like, can obviously enhance the wear resistance of a base material, and has good chemical stability.

2. The AlCrSiN/Mo coating after heat treatment is made of AlN, CrN and Mo₂The nanocrystalline such as N and the like is embedded in the amorphous layer to form a nano composite structure, dislocation can not be formed in the fine nanocrystalline, the thin amorphous layer between crystal grains can effectively prevent the sliding of crystal boundary, a large number of two-phase interfaces increase the expansion resistance of microcracks, and the high-temperature thermal stability of the coating is good.

3. The AlCrSiN/Mo coating after heat treatment has smooth surface, compact structure, good tribological performance and good toughness, wherein the wear rate is about 4.05 × 10^-4μm³/N·μm。

4、AlCrN/MoS₂The coating has good repeatability of the heat treatment process, has wider application prospect, can be used for cutting various difficult-to-process materials at high speed, and has unique advantages.

5. The self-lubricating coating prepared by the invention is suitable for the field of modern high-speed dry cutting, and can obviously improve the service life and the processing efficiency of the cutter; the special working conditions that fluid lubrication cannot be implemented, such as high temperature, high load, ultralow temperature, ultrahigh vacuum, strong oxidation, strong radiation and the like, can be met, and the application prospect on high-speed cutting tools is wide.

Drawings

FIG. 1 shows the surface morphology of AlCrSiN/Mo coatings after vacuum heat treatment at 700 ℃.

FIG. 2 is a cross-sectional view of the AlCrSiN/Mo coating after vacuum heat treatment at 700 ℃.

FIG. 3 is an XRD pattern of AlCrSiN/Mo coatings after vacuum heat treatment at 700 ℃.

FIG. 4 shows the scratch morphology of AlCrSiN/Mo coatings after 700 ℃ vacuum heat treatment.

FIG. 5 is the H/E value and H of AlCrSiN/Mo coatings after vacuum heat treatment in the as-deposited state and at different temperatures³/E*²The value is obtained.

FIG. 6 shows the wear scar morphology of AlCrSiN/Mo coatings after 700 ℃ vacuum heat treatment.

FIG. 7 shows the wear scar morphology of the AlCrSiN/Mo coating after vacuum heat treatment at 800 ℃.

Detailed Description

The technical scheme of the invention is further explained by combining specific examples.

The invention adopts a vacuum tube furnace to carry out heat treatment on the AlCrSiN/Mo nano composite coating, and obtains the AlCrSiN/Mo nano composite coating with excellent comprehensive performance by controlling the heating rate, the heat preservation time and the cooling rate in different stages. The process specifically comprises the following steps:

(1) fixing the sample deposited with AlCrSiN/Mo nano composite coating in a ceramic crucible, and then pumping the vacuum degree of a vacuum tube to be less than 3 × 10^-3Pa；

(2) Heating the AlCrSiN/Mo coating sample to improve the microstructure of the coating so as to improve the tribological performance of the coating;

in the heat treatment process, heating is carried out in a step variable speed heating mode, and the temperature is firstly increased to the temperature T according to the heating rate of 7 ℃/min₁，T₁(T-90 ℃ C.) to (T-110 ℃ C.); then the temperature is raised to the temperature T at the temperature rise rate of 10 ℃/min₂，T₂(T-20 ℃ C.) - (T-50 ℃ C.); finally, the temperature is increased to the temperature T at the temperature increase rate of 8 ℃/min.

During the heat treatment, when the temperature is raised to T₂When the temperature is close to the heat preservation temperature T, the temperature rise rate is reduced, and the buffering effect is achieved until the temperature is heated to the required heat preservation temperature.

Samples of the invention with AlCrSiN/Mo coatings deposited were prepared according to the procedure in PCT/CN 2019/125596.

The procedure for preparing AlCrSiN/Mo coating samples in example 1 and comparative example 1 below is as follows:

an AlCrSiN/Mo coating is deposited on a single crystal Si sheet (40mm × 40mm × 0.67mm) and a high temperature alloy substrate (35mm × 35mm × 1.5mm) by using a HiPIMS/Pulse DC composite magnetron sputtering system, and the preparation process of the coating is as follows:

(1) all substrates were sequentially in acetoneUltrasonic cleaning in ethanol for 30min, and treating with high purity N₂Drying and fixing on a rotating bracket in the vacuum chamber. The Cr target is connected to an electric arc power supply, the CrMo target is connected to a pulse direct current magnetron sputtering power supply, and the AlCrSi target is connected to a high-power pulse magnetron sputtering power supply.

The rotating speed of the rotating bracket is set to be 2.5r/min, and the target base distances are respectively 80mm (AlCrSi target), 80mm (CrMo target) and 280mm (Cr target). Respectively introducing Ar and N into working gas and reaction gas in the film plating process₂(the purity is 99.999%).

(2) Glow discharge cleaning, pumping background vacuum degree to less than 3.0 × 10^-3Pa, heating the coating chamber to 400 ℃, applying-800V bias voltage, introducing Ar with the flow of 200sccm, keeping the working pressure at 1.5Pa, and performing glow discharge cleaning for 15 min; removing the pollutants on the surface of the substrate.

(3) Ion bombardment, namely starting an electric arc Cr target for ion bombardment after glow discharge cleaning, setting an arc source current of 90A and an arc source voltage of 20V-20.3V, introducing Ar with the flow of 200sccm, and keeping the working pressure of 5 × 10^-1And Pa, ion bombardment cleaning for 8min to improve the film-substrate interface bonding and improve the bonding strength of the coating.

(4) Depositing a CrN transition layer: keeping the parameters of the arc Cr target unchanged, introducing Ar with the flow rate of 50sccm and N₂The flow rate is 200sccm, and the working pressure is kept at 8 × 10^-1Pa, depositing a CrN transition layer for 15min, reducing the difference of thermal expansion coefficients between the coating and the substrate, and improving the film/substrate binding force.

(5) Preparing an AlCrSiN/Mo self-lubricating film: reducing the bias voltage to-150V, and introducing a reaction gas N₂The flow rate is 50sccm, the flow rate of Ar is 250sccm, and Ar and N are maintained₂The total flow is 300sccm, the deposition pressure is adjusted to be 1.6Pa, the sputtering power of a CrMo target is 0.4kW, the sputtering power of an AlCrSi target is 1.2kW, the deposition time is strictly controlled for 360min, and the AlCrSiN/Mo composite film is prepared, wherein the chemical components of the prepared AlCrSiN/Mo self-lubricating film are shown in Table 1, and the minimum wear rate of the film is about 1.52 × 10^-3μm³/N·μm。

TABLE 1 coating compositions prepared at a deposition pressure of 1.6Pa

Deposition pressure (Pa)	Al(at.％)	Cr(at.％)	Mo(at.％)	Si(at.％)	N(at.％)
						1.6	16.4	31.2	5.1	1.9	45.4