A method for preparing a controllable Ti-Al-C system MAX phase coating

Abstract

The invention discloses a method for preparing an adjustable Ti-Al-C system MAX phase coating, comprising: using a Ti-Al composite target as a sputtering target, using a hydrocarbon gas as a reaction gas source, the flow rate of the hydrocarbon gas being 5-12 sccm, using DC magnetron sputtering, sputtering a cleaned substrate surface to obtain a Ti-Al-C coating, heating the Ti-Al-C coating to 600-700°C, and keeping the temperature for 60-180 minutes to obtain a Ti-Al-C system MAX phase coating. The method can simply and efficiently regulate different Ti-Al-C system MAX phases, and can also reduce the heat treatment temperature.

Description

Technical Field

[0001] The invention relates to the technical field of surface treatment, in particular to a method for preparing an adjustable Ti-Al-C system MAX phase coating. Background Art

[0002] MAX phase materials are a class of thermodynamically stable, layered, high-performance ceramic-metal materials with a close-packed hexagonal structure. n+1 AX n , where the M position is an early transition metal element, including Ti, Cr, etc., the A position is usually an element of Group ⅢA or ⅣA in the periodic table, such as Al, Si, etc., and the X position element is C or N. It can be understood as a metal carbide or metal nitride nanolayered compound divided by a single layer of A atoms.

[0003] Generally speaking, MX is bonded by strong covalent and ionic bonds, while MA relies on relatively weak metallic bonds. This unique layered structure and bonding method make the MAX phase have the excellent properties of both metals and ceramics, such as excellent mechanical stability, high hardness, good thermal shock resistance, strong corrosion resistance and high temperature oxidation resistance, good electrical and thermal conductivity, as well as self-healing properties and machinability, etc. It has a wide range of applications in high-tech fields such as nuclear energy, ocean, aerospace, automobile, biomedicine, etc.

[0004] In the general formula M n+1 AX n In the formula, the n value indicates that the number of M atoms between every two layers of A atoms in the MAX phase crystal structure is n+1. Currently, the n values ​​of most known MAX phase materials are 1, 2, and 3. According to the different n values, the MAX phase is divided into 211, 312, and 413 phases. Among them, the typical Al-containing MAX phase material exhibits significant high-temperature oxidation resistance and corrosion resistance by forming a protective Al2O3 layer. In the most representative Ti-Al-C system and Cr-Al-C system, Ti-Al-C compounds have a thermal expansion coefficient similar to Al2O3, making them suitable protective coatings for substrates such as stainless steel, titanium alloys, and nickel-based high-temperature alloys.

[0005] The Ti-Al-C MAX phase includes two types: 211 phase Ti2AlC and 312 phase Ti3AlC2. Both have similar bonding characteristics and band structures, and similar performance. At present, the main preparation methods of Ti2AlC and Ti3AlC2 are cathode arc sputtering or magnetron sputtering in physical vapor deposition (PVD) technology. Since the synthesis of the relatively complex MAX phase long c-axis crystal structure requires sufficient diffusion rate to divide the elements, the formation of both phases requires high heat treatment temperature (800-1000℃). Ti3AlC2 has a longer c-axis, so the phase formation temperature is higher.

[0006] How to achieve the preparation of 211 phase and 312 phase at a lower temperature so that Ti-Al-C MAX has stronger adaptability to different types of substrates, and how to regulate the different phases of Ti-Al-C MAX based on demand are issues that need to be solved urgently. Summary of the invention

[0007] The present invention provides a method for preparing an adjustable Ti-Al-C series MAX phase coating, which can simply and efficiently adjust different Ti-Al-C series MAX phases and simultaneously reduce the heat treatment temperature.

[0008] A method for preparing an adjustable Ti-Al-C system MAX phase coating, comprising:

[0009] A Ti-Al composite target is used as a sputtering target, and a hydrocarbon gas is used as a reaction gas source. The flow rate of the hydrocarbon gas is 5-12 sccm. An inert gas is continuously introduced, and DC magnetron sputtering is used to sputter the cleaned substrate surface to obtain a Ti-Al-C coating. The Ti-Al-C coating is heated to 600-700°C and kept warm for 60-180 minutes to obtain a Ti-Al-C series MAX phase coating.

[0010] Furthermore, the flow rate of the hydrocarbon gas is 5-8 sccm, and the obtained Ti-Al-C system MAX phase is 211 phase.

[0011] Furthermore, the flow rate of the hydrocarbon gas is 9-12 sccm, and the obtained Ti-Al-C system MAX phase is 312 phase.

[0012] Furthermore, the hydrocarbon gas is acetylene or methane.

[0013] The present invention utilizes direct current magnetron sputtering technology combined with hydrocarbon gas flow rate to provide a sufficient amount of carbon atoms per unit area of ​​the substrate surface, thereby reducing the heat treatment temperature of 211 and 312 phases, and by controlling the hydrocarbon gas flow rate, the 211 phase and the 312 phase can be obtained as required, thereby achieving regulation of the preparation of the 211 phase and the 312 phase, and in combination with direct current magnetron sputtering technology, under the condition of a larger hydrocarbon gas flow rate, a Ti-Al-C system MAX phase with a dense structure, a smooth surface, and uniform and fine grains is obtained as the 211 phase.

[0014] The inert gas is argon or nitrogen, and the flow rate of the inert gas is 150-200 sccm.

[0015] The parameters of the DC magnetron sputtering are: sputtering target power is 1500-2500W, substrate negative bias voltage is 0-100V, chamber pressure is 0.6-1.2Pa, deposition time is 60-180min, vacuum degree is less than 1-3×10 -5 Pa.

[0016] The Ti-Al element ratio of the Ti-Al composite target is 2:1.2-1.5.

[0017] The steps of cleaning the substrate surface are as follows:

[0018] The substrate surface is ground with 400# to 2000# SiC sandpaper, and then ultrasonically cleaned in acetone for 10-15 minutes after polishing pretreatment.

[0019] The substrate is stainless steel or titanium-based alloy.

[0020] After cleaning the surface of the substrate, plasma glow etching is performed, and the parameters of the plasma glow etching are: plasma flow rate is 30-35sccm, ion source voltage is 1000-1200V, negative bias voltage is applied to the substrate 150-250V, and etching time is 20-40min. The plasma glow etching process makes the substrate and the sputtering coating more closely bonded.

[0021] The plasma is any one of argon and nitrogen.

[0022] After the substrate is subjected to plasma glow etching treatment, a transition layer is sputtered on the surface of the substrate.

[0023] The step of sputtering a transition layer on the substrate surface is: closing the reaction source, introducing protective gas, and starting the Ti-Al composite target to perform DC sputtering on the substrate.

[0024] Furthermore, the transition layer is a TiAl compound.

[0025] Furthermore, the sputtering parameters are: sputtering power 1800-2400W, substrate bias voltage -100-0V.

[0026] Furthermore, the flow rate of the protective gas is 150-250 sccm, and the cavity gas pressure is 0.6-1.2 Pa.

[0027] Furthermore, before heating the Ti-Al-C coating, the vacuum degree is controlled to be less than 1-3×10 -3 Pa.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The reactive magnetron sputtering deposition using Ti-Al composite target and hydrocarbon gas can easily control the composition of 211 phase and 312 phase in the coating after heat treatment and regulate the phase purity by adjusting the flow rate of the reactive gas; thus, it is helpful to meet the application needs in different fields according to the performance advantages of the components.

[0030] (2) By regulating the flow rate of the reaction gas hydrocarbon gas, the dependence of the 312 phase on the annealing temperature is improved, and the annealing temperature of the 312 phase is reduced to a certain extent. That is, the preparation of the 211 phase or 312 phase at a lower temperature is achieved simply by regulating the flow rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The XRD spectra of the Ti-Al-C system MAX phase coatings prepared in Examples 1 to 3 are shown.

[0032] Figure 2 Surface morphology images of the Ti-Al-C series MAX phase coatings prepared in Examples 1 to 3, wherein 2(a) is the surface morphology image of the Ti-Al-C series MAX phase coating prepared in Example 1, 2(b) is the surface morphology image of the Ti-Al-C series MAX phase coating prepared in Example 2, and 2(c) is the surface morphology image of the Ti-Al-C series MAX phase coating prepared in Example 3. DETAILED DESCRIPTION

[0033] The embodiment of the present invention mainly uses a Ti-Al composite target as a sputtering target and a hydrocarbon gas as a reaction gas in a protective gas, and controls and regulates the Ti-Al-C system MAX phase component in the coating by adjusting the flow rate of the hydrocarbon gas.

[0034] The technical solution of the present invention is further described in detail below in conjunction with the preferred embodiments and the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and a detailed implementation method and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

[0035] Embodiment 1:

[0036] In this embodiment, the substrate material is 1Cr11Ni2W2MoV stainless steel, and the specific preparation steps of the substrate surface coating are as follows:

[0037] Step 1: Use 400#~2000# SiC sandpaper to grind the surface of 1Cr11Ni2W2MoV stainless steel in turn, and then use diamond grinding paste to polish for 20 minutes.

[0038] Step 2: Place the ground and polished 1Cr11Ni2W2MoV stainless steel substrate in acetone for ultrasonic cleaning for 10 minutes, then blow dry with cold air and stick it on the sample holder with conductive glue for later use.

[0039] Step 3: Place the sample holder with the substrate attached in the deposition chamber and wait for the mechanical pump and molecular pump to evacuate to 3×10 -5 Pa, set the chamber temperature to 100°C, introduce 34 sccm of high-purity argon into the vacuum chamber, set the linear anode ion source current to 0.2A, and the substrate bias to -200V, and etch and clean the surface of 1Cr11Ni2W2MoV stainless steel for 30 minutes.

[0040] Step 4: The deposition conditions of the Ti-Al transition layer are the same as those in step 5 below, except that different gases are used. No hydrocarbon reaction gas is used for the deposition of the transition layer, but only 200 sccm of high-purity argon gas is used.

[0041] Step 5: Using the Ti-Al composite target as the sputtering target, high-purity argon gas is introduced into the cavity, and high-purity methane gas is used as the reaction gas to perform reactive magnetron sputtering deposition to obtain a coating containing three elemental components of Cr, Al, and C. The flow rate of high-purity argon gas is 200 sccm, the flow rate of high-purity methane is 5 sccm, the Ti:Al ratio of the sputtering target is 2:1.5, the sputtering power is 2000 W, the substrate bias is 0 V, the cavity pressure is 1 Pa, and the deposition time is 120 min.

[0042] Step 6: Place the deposited Ti-Al-C coating in an annealing furnace with a vacuum degree of less than 2×10 -3 Pa, keep warm at 700℃ for 90min.

[0043] Step 7: Perform XRD and SEM tests on the coating prepared above.

[0044] Figure 1 and Figure 2 They are the X-ray diffraction and scanning electron microscopy test spectra of the prepared coating at a certain methane reaction gas flow rate. Figure 1 As shown, the coating composition in Example 1 is mainly TiAl intercompounds and a small amount of Ti2AlC peaks detected. Figure 2 In the SEM test shown in (a), the surface is flat and dense.

[0045] Embodiment 2:

[0046] In this embodiment, the substrate material is 1Cr11Ni2W2MoV stainless steel, and the specific preparation steps of the substrate surface coating are as follows:

[0047] Step 1: Use 400#~2000# SiC sandpaper to grind the surface of 1Cr11Ni2W2MoV stainless steel in turn, and then use diamond grinding paste to polish for 20 minutes.

[0048] Step 2: Place the ground and polished 1Cr11Ni2W2MoV stainless steel substrate in acetone for ultrasonic cleaning for 10 minutes, then blow dry with cold air and stick it on the sample holder with conductive glue for later use.

[0049] Step 3: Place the sample holder with the substrate attached in the deposition chamber and wait for the mechanical pump and molecular pump to evacuate to 3×10 -5 Pa, set the chamber temperature to 100°C, introduce 34 sccm of high-purity argon into the vacuum chamber, set the linear anode ion source current to 0.2A, and the substrate bias to -200V, and etch and clean the surface of 1Cr11Ni2W2MoV stainless steel for 30 minutes.

[0050] Step 4: The deposition conditions of the Ti-Al transition layer are the same as those in step 5 below, except that different gases are used. No hydrocarbon reaction gas is used for the deposition of the transition layer, but only 200 sccm of high-purity argon gas is used.

[0051] Step 5: Using the Ti-Al composite target as the sputtering target, high-purity argon gas and high-purity methane gas as reaction gases are introduced into the cavity to perform reactive magnetron sputtering deposition to obtain a coating containing three elemental components of Cr, Al, and C, wherein the flow rate of high-purity argon gas is 200 sccm, the flow rate of high-purity methane is 7.5 sccm, the Ti:Al ratio of the sputtering target is 2:1.5, the sputtering power is 2000 W, the substrate bias is 0 V, the cavity pressure is 1 Pa, and the deposition time is 120 min.

[0052] Step 6: Place the deposited Ti-Al-C coating in an annealing furnace with a vacuum degree of less than 2×10 -3 Pa, keep warm at 700℃ for 90min.

[0053] Step 7: Perform XRD and SEM tests on the coating prepared above.

[0054] Figure 1 and Figure 2 They are the X-ray diffraction and scanning electron microscopy test spectra of the prepared coating at a certain methane reaction gas flow rate. Figure 1 As shown, the TiAl compound in the coating component of Example 2 disappears, and the main component of the coating is transformed into Ti2AlC. Figure 2 In the scanning electron microscope test shown in (b), the surface is flat and dense, some particles are aggregated, and the grain size is 0.24μm.

[0055] Embodiment 3:

[0056] In this embodiment, the substrate material is 1Cr11Ni2W2MoV stainless steel, and the specific preparation steps of the substrate surface coating are as follows:

[0057] Step 1: Use 400#~2000# SiC sandpaper to grind the surface of 1Cr11Ni2W2MoV stainless steel in turn, and then use diamond grinding paste to polish for 20 minutes.

[0058] Step 2: Place the ground and polished 1Cr11Ni2W2MoV stainless steel substrate in acetone for ultrasonic cleaning for 10 minutes, then blow dry with cold air and stick it on the sample holder with conductive glue for later use.

[0059] Step 3: Place the sample holder with the substrate attached in the deposition chamber and wait for the mechanical pump and molecular pump to evacuate to 3×10 -5 Pa, set the chamber temperature to 100°C, introduce 34 sccm of high-purity argon into the vacuum chamber, set the linear anode ion source current to 0.2A, and the substrate bias to -200V, and etch and clean the surface of 1Cr11Ni2W2MoV stainless steel for 30 minutes.

[0060] Step 4: The deposition conditions of the Ti-Al transition layer are the same as those in step 5 below, except that different gases are used. No hydrocarbon reaction gas is used for the deposition of the transition layer, but only 200 sccm of high-purity argon gas is used.

[0061] Step 5: Using the Ti-Al composite target as the sputtering target, high-purity argon gas and high-purity methane gas as reaction gases are introduced into the cavity to perform reactive magnetron sputtering deposition to obtain a coating containing three elemental components of Cr, Al, and C, wherein the flow rate of high-purity argon gas is 200 sccm, the flow rate of high-purity methane is 10 sccm, the Ti:Al ratio of the sputtering target is 2:1.5, the sputtering power is 2000 W, the substrate bias is 0 V, the cavity pressure is 1 Pa, and the deposition time is 120 min.

[0062] Step 6: Place the deposited Ti-Al-C coating in an annealing furnace with a vacuum degree of less than 2×10 -3 Pa, keep warm at 700℃ for 90min.

[0063] Step 7: Perform XRD and SEM tests on the coating prepared above.

[0064] Figure 1 and Figure 2 They are the X-ray diffraction and scanning electron microscopy test spectra of the prepared coating at a certain methane reaction gas flow rate. Figure 1 As shown, the coating composition in Example 3 is changed from Ti2AlC to Ti3AlC2. Figure 2In the scanning electron microscope test shown in (c), the surface is flat and dense, the particles become refined, and the grain size is 0.13μm.

Claims

1. A method for preparing a controllable Ti-Al-C MAX phase coating, It is characterized in that include: A Ti-Al composite target is used as a sputtering target, a hydrocarbon gas is used as a reaction gas source, an inert gas is continuously introduced, and a DC magnetron sputtering is used to perform DC magnetron sputtering on the cleaned substrate surface to obtain a Ti-Al-C coating, and the Ti-Al-C coating is heated to 600-700° C. and kept warm for 60-180 minutes to obtain a Ti-Al-C series MAX phase coating; The flow rate of the hydrocarbon gas is 7.5 sccm, and the Ti-Al-C system MAX phase is 211 phase; The flow rate of the hydrocarbon gas is 10 sccm, and the Ti-Al-C system MAX phase is 312 phase; The flow rate of the inert gas is 200 sccm; The parameters of the DC magnetron sputtering are: sputtering target power is 1500-2500W, substrate negative bias voltage is 0-100V, chamber pressure is 0.6-1.2Pa, deposition time is 60-180min, vacuum degree is less than 1-3×10 -5 Pa; The Ti-Al element ratio of the Ti-Al composite target is 2:1.2-1.

5.

2. The method for preparing the controllable Ti-Al-C MAX phase coating according to any one of claim 1, It is characterized in that The hydrocarbon gas is acetylene or methane.

3. The method for preparing the controllable Ti-Al-C system MAX phase coating according to claim 1, It is characterized in that Cleaning the substrate surface comprises: The substrate surface is ground with 400# to 2000# SiC sandpaper, and then ultrasonically cleaned in acetone for 10-15 minutes after polishing pretreatment.

4. The method for preparing the controllable Ti-Al-C MAX phase coating according to claim 1, It is characterized in that The substrate is stainless steel or titanium-based alloy.

5. The method for preparing the controllable Ti-Al-C MAX phase coating according to claim 4, It is characterized in that After cleaning the substrate surface, plasma glow etching is performed, and the parameters of the plasma glow etching are: plasma flow rate is 30-35sccm, ion source voltage is 1000-1200V, negative bias voltage of 150-250V is applied to the substrate, and etching time is 20-40min.

6. The method for preparing the controllable Ti-Al-C MAX phase coating according to claim 5, It is characterized in that After the substrate is subjected to plasma glow etching treatment, a transition layer is sputtered on the surface of the substrate, wherein the transition layer is a TiAl intermetallic compound.

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