Process for preparing AlOx-containing hard coating at low temperature through arc plasma

Abstract

The invention discloses a process for low-temperature preparation of a hard coating containing AlOx by arc plasma, and relates to the field of high-temperature alloy processing. The coating contains four elements of Ti, Al, N and O, and is a TiAlN / AlOx / TiAlN composite coating, and the preparation process mainly comprises the following steps: etching and cleaning Ar ions on the surface of a matrix; a TiAl target is started, N2 gas is introduced, and a TiAlN layer is deposited; opening the aluminum alloy target, and introducing N2 gas and O2 gas with gradually changed flow rates to deposit an AlON transition layer; opening the aluminum alloy target and introducing O2 gas to deposit an AlOx layer; and then depositing the AlON transition layer and the TiAlN surface layer again. The prepared TiAlN / AlOx / TiAlN composite coating has the characteristics of high-temperature chemical reaction adhesion and corrosion resistance, low heat conductivity, good thermal barrier, low friction, high lubricity and the like of a tool nose for cutting difficult-to-machine materials under an extremely high-temperature condition, crescent corrosion of a front tool face can be effectively reduced, abrasion of a rear tool face and abnormal hot crack failure of a blade can be reduced, and the service life of the blade is prolonged. And the current high-temperature alloy processing requirements can be met.

Description

Technical Field

[0001] This invention relates to the field of hard coating technology, specifically to a process for preparing AlOx-containing hard coatings at low temperature using arc plasma. Background Technology

[0002] With the demands of industrial development, both civilian and aerospace / military industries are increasingly using difficult-to-machine materials, such as high-hardness materials with a hardness greater than HRC60, high-temperature alloys such as nickel-based, titanium-based, and iron-based alloys, and carbon fibers. The machining of these materials presents common challenges: a) intense plastic deformation, shearing, severe friction, and impact vibration; b) the generation of extremely high cutting heat; c) high temperatures leading to tool coating oxidation and softening failure of the base material, chemical reactions on the rake face causing chip adhesion, severe adhesive friction resulting in crater corrosion wear, and rapid erosion on the flank face.

[0003] In the field of high-temperature alloy machining, besides the research and development of insert substrate formulations and sintering processes, the surface coating of the inserts is also a crucial aspect. For this type of machining, the insert coating needs to meet the following conditions: a) It must have good thermal barrier properties, reducing heat transfer to the tool substrate. b) It must be resistant to high-temperature chemical corrosion, not reacting chemically with high-temperature chips under harsh conditions to prevent adhesion and corrosion. c) It must exhibit low friction under high-temperature conditions, resulting in rapid chip removal and minimal heat generation. This achieves the goals of reducing chip adhesion on the rake face, reducing crater corrosion wear, and reducing flank wear when cutting difficult-to-machine materials.

[0004] Alumina coatings possess excellent properties, such as high-temperature stability, chemical stability, and low thermal and electrical conductivity. Currently, chemical vapor deposition (CVD) coatings are widely used as wear-resistant coating materials for cemented carbide cutting inserts. However, CVD coatings are typically prepared at high temperatures (1000℃), resulting in a narrow range of compatible substrate materials. In contrast, PVD methods, using a temperature range of 350-600℃, can be applied to a wider spectrum of cemented carbide materials, as well as high-speed steel and die steel. Furthermore, the coating thickness is significantly reduced compared to the 8-15μm required by CVD methods, requiring only 1-4μm, making it suitable for use with sharp cutting edges.

[0005] This invention combines the advantages of alumina coatings to prepare TiAlN / AlO materials that are resistant to high-temperature corrosion, have low thermal conductivity, and low friction. x The TiAlN composite coating effectively reduces crater corrosion on the rake face, reduces wear on the flank face, and reduces abnormal thermal cracking failure of the cutting tool. Summary of the Invention

[0006] The purpose of this invention is to provide a method for low-temperature preparation of AlO2-containing materials using arc plasma. x The hard coating process includes the following steps:

[0007] Step 1: Pre-treatment of the substrate surface. Use organic solvent to ultrasonically clean the workpiece to remove stains from the surface and then blow dry it for later use.

[0008] Step 2: Ar ion etching. Argon gas is introduced and ignition discharge is initiated to form Ar ions. The ions bombard the workpiece surface, remove surface impurities, and enhance the adhesion between the film and the substrate.

[0009] Step 3: TiAlN, AlO x For the deposition of TiAlN composite coatings, a Ti (33-50 at%) / Al (67-50 at%) target is opened and N2 gas is introduced to deposit the TiAlN underlayer. An aluminum alloy Al (50-70 at%) / Cr (50-30 at%) target is opened and N2 and O2 gases with gradually varying flow rates are introduced to deposit the AlON transition layer. An aluminum alloy Al (50-70 at%) / Cr (50-30 at%) target is opened and O2 gas is introduced to deposit AlO. x The first layer is deposited, followed by an AlON transition layer and a TiAlN surface layer.

[0010] Preferably, the ultrasonic cleaning of the substrate surface can also be performed using deionized water.

[0011] Preferably, the final coating consists of a TiAlN underlayer, an AlON transition layer, and an AlO layer. x It consists of an intermediate layer, an AlON transition layer, and a TiAlN surface layer. The AlON transition layer contains two layers, which are located in AlO. x Both sides of the middle layer.

[0012] Preferably, the specific process parameters for the Ar ion etching are: temperature 500-600℃, argon flow rate 100-300 sccm, pulse bias voltage 80-150V, ion etching current 120-150A, and etching time 60-90min.

[0013] Preferably, the specific process for depositing the TiAlN underlayer in step three is as follows: target current 150-250A, coil current 1.0-2.0A, target-substrate distance 120-220mm, N2 gas flow rate 1000-1200sccm, vacuum degree 2.0-3.5Pa. First, a TiAlN layer of 0.8-1.0μm is deposited under a bias voltage of 30-50V, and then a TiAlN layer of 0.4-0.6μm is deposited under a bias voltage of 80-100V. The TiAl target is then turned off.

[0014] Preferably, the specific process for depositing the AlON transition layer in step three is as follows: target current 160-180A, target-substrate distance 120-220mm, N2 gas flow rate gradually decreasing from 1000-1200sccm to 50-100sccm, O2 gas flow rate gradually increasing from 50-100sccm to 200-400sccm, bias voltage 60-80V, and the entire process takes only 3-5 minutes.

[0015] Preferably, in step three, AlO is deposited. x The specific process for the layer is as follows: stop the N2 gas supply, deposit an AlO layer, further increase the O2 gas flow rate to 300-500 sccm, target current 180-200 A, target-substrate distance 120-220 mm, vacuum degree 0.8-1.0 Pa, bias voltage 60-80 V, and co-deposit an AlO layer of 0.3-0.4 μm.

[0016] Preferably, the specific process for redepositing the AlON transition layer in step three is as follows: N2 gas is introduced, the target current is 160-180A, the target-substrate distance is 120-220mm, the N2 gas flow rate gradually increases from 50-100sccm to 1000-1200sccm, the O2 gas flow rate gradually decreases from 200-400sccm to 50-100sccm, the bias voltage is 60-80V, and the deposition takes 3-5 minutes.

[0017] Preferably, the specific process for depositing the TiAlN surface layer in step three is as follows: turn on the TiAl target, turn off the aluminum alloy target and stop the O2 gas supply, target current 150-250A, coil current 1.0-2.0A, target-substrate distance 120-220mm, N2 gas flow rate 1000-1200sccm, vacuum degree 2.0-3.5Pa, and deposit 0.5-0.6μm under a bias voltage of 80-100V.

[0018] Compared with the prior art, the beneficial effects of the present invention are: the present invention uses low temperature PVD technology of less than 500℃ to deposit alumina coating, which enables the alumina coating to be more widely used on cemented carbide materials, high-speed steel, and mold steel.

[0019] Applying alumina coatings, which possess high-temperature stability, chemical stability, and low thermal and electrical conductivity, to composite hard coatings significantly improves the performance of TiAlN / AlO4. x The TiAlN composite coating exhibits comprehensive performance characteristics that meet the requirements of high-temperature alloy machining. Tool coatings must resist high-temperature chemical adhesion and corrosion, possess low thermal conductivity and a good thermal barrier, and exhibit low friction and high lubricity under extremely high-temperature conditions at the cutting tip of difficult-to-machine materials. This effectively reduces crater corrosion on the rake face, reduces flank wear, and minimizes abnormal thermal cracking failure of the cutting tool. Furthermore, the coating thickness is only 1-4 μm, making it suitable for use with sharp cutting tool tips. Attached Figure Description

[0020] Figure 1 Drawings of materials that are difficult to machine;

[0021] Figure 2 This is a schematic diagram of the cutting process;

[0022] Figure 3 This is a schematic diagram of cutting tool failure;

[0023] Figure 4 TiAlN / AlO x Cross-sectional characterization diagram of the / TiAlN composite coating. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] Example 1

[0026] Using YG6 cutting tools as the substrate, TiAlN / AlO was deposited using AlTi 50-67 / 50-33at% alloy targets and AlCr 50-70 / 50-30at% alloy targets. x The specific process steps for the / TiAlN composite coating are as follows:

[0027] Step 1: Pretreatment of substrate surface: Use organic solvent or deionized water to ultrasonically clean the workpiece to remove stains on the surface and then blow dry for later use.

[0028] Step 2: Ar ion etching: Argon gas is introduced and ignition discharge is initiated to form Ar ions. The ions bombard the workpiece surface, removing surface impurities and enhancing the adhesion between the film and the substrate. Temperature: 500-600℃, Argon gas flow rate: 100-300 sccm, pulse bias voltage: 80-150V, ion etching current: 120-150A, etching time: 60-90min.

[0029] Step 3: TiAlN / AlO xDeposition of the TiAlN composite coating: Turn on the TiAl target and purge with N2 gas to deposit the TiAlN underlayer. Target current: 150-250 A; coil current: 1.0-2.0 A; target-substrate distance: 120-220 mm; N2 gas flow rate: 1000-1200 sccm; vacuum: 2.0-3.5 Pa. First, deposit a 0.8-1.0 μm TiAlN layer under a bias of 30-50 V, then deposit a 0.4-0.6 μm TiAlN layer under a bias of 80-100 V. Turn off the TiAl target and turn on the aluminum alloy target, purging with N2 and O2 gas to deposit the AlON transition layer. Target current: 160-180 A; target-substrate distance: 120-220 mm; N2 gas flow rate gradually decreases from 1000-1200 sccm to 50-100 sccm; O2 gas flow rate gradually decreases from 50-100 sccm. The N2 gas flow rate is gradually increased to 200-400 sccm, with a bias voltage of 60-80V, for a total of 3-5 minutes. The N2 gas flow is then stopped, and an AlO layer is deposited. The O2 gas flow rate is further increased to 300-500 sccm, the target current is 180-200 A, the target-substrate distance is 120-220 mm, the vacuum degree is 0.8-1.0 Pa, and the bias voltage is 60-80V, resulting in a total AlO layer thickness of 0.3-0.4 μm. N2 gas is then introduced again to deposit an AlON transition layer, with a target current of 160-180 A, a target-substrate distance of 120-220 mm, and the N2 gas flow rate gradually increased from 50-100 sccm to 1000-1200 sccm. The O2 gas flow rate is gradually decreased from 200-400 sccm to 50-100 sccm, with a bias voltage of 60-80V, for a total deposition time of 3-5 minutes. Finally, the N2 gas flow is turned on again.

[0030] With a TiAl target, the aluminum alloy target is turned off and the O2 gas supply is stopped to deposit a TiAlN surface layer. The target current is 150-250A, the coil current is 1.0-2.0A, the target-substrate distance is 120-220mm, the N2 gas flow rate is 1000-1200sccm, the vacuum degree is 2.0-3.5Pa, and a thickness of 0.5-0.6μm is deposited under a bias voltage of 80-100V.

[0031] like Figure 4 As shown, this is the deposited TiAlN / AlO x The cross-sectional morphology of the / TiAlN composite coating is shown to be dense and uniform with no obvious defects, and the total thickness is 2-2.2 μm. Testing revealed that the coating exhibits a scratch adhesion strength of 60-75 N and a nanoindentation hardness of 28-32 GPa, meeting the requirements for high-performance tool coatings.

[0032] Comparative Example 1

[0033] The difference from Example 1 is that AlO is not added. x The process involves depositing a pure TiAlN layer, with the following specific steps:

[0034] Step 1: Pretreatment of substrate surface: Use organic solvent or deionized water to ultrasonically clean the workpiece to remove stains on the surface and then blow dry for later use.

[0035] Step 2: Ar ion etching: Argon gas is introduced and ignition discharge is initiated to form Ar ions. The ions bombard the workpiece surface, removing surface impurities and enhancing the adhesion between the film and the substrate. Temperature: 500-600℃, Argon gas flow rate: 100-300 sccm, pulse bias voltage: 80-150V, ion etching current: 120-150A, etching time: 60-90min.

[0036] Step 3: Deposition of TiAlN coating: Turn on the TiAl target and purge with N2 gas to deposit the TiAlN layer. Target current 150-250A, coil current 1.0-2.0A, target-substrate distance 120-220mm, N2 gas flow rate 1000-1200sccm, vacuum degree 2.0-3.5Pa. First, deposit a TiAlN layer of 0.8-1.0μm under a bias voltage of 30-50V, and then deposit a TiAlN layer of 1.4-1.6μm under a bias voltage of 80-100V.

[0037] Testing revealed that the coating exhibited a scratch adhesion strength of 40-60 N and a nano-indentation hardness of 30-35 GPa. A comparison with the performance of Example 1 shows that AlO₂… x The addition of the layer greatly improves the adhesion of the coating, while the hardness only decreases slightly.

[0038] Comparative Example 2

[0039] The difference from Example 1 is that a TiAlN / AlO / TiAlN composite coating is deposited, but an AlON gradient transition layer is not used. The specific process steps are as follows:

[0040] Step 1: Pretreatment of substrate surface: Use organic solvent or deionized water to ultrasonically clean the workpiece to remove stains on the surface and then blow dry for later use.

[0041] Step 2: Ar ion etching: Argon gas is introduced and ignition discharge is initiated to form Ar ions. The ions bombard the workpiece surface, removing surface impurities and enhancing the adhesion between the film and the substrate. Temperature: 500-600℃, Argon gas flow rate: 100-300 sccm, pulse bias voltage: 80-150V, ion etching current: 120-150A, etching time: 60-90min.

[0042] Step 3: Deposition of TiAlN / AlO / TiAlN composite coating: Turn on the TiAl target and purge with N2 gas to deposit the TiAlN underlayer. Target current: 150-250A; coil current: 1.0-2.0A; target-substrate distance: 120-220mm; N2 gas flow rate: 1000-1200sccm; vacuum degree: 2.0-3.5Pa. First, deposit a 0.8-1.0μm TiAlN layer under a bias of 30-50V, then deposit a 0.4-0.6μm TiAlN layer under a bias of 80-100V. Turn off the TiAl target and N2 gas, turn on the aluminum alloy target and purge with O2 gas to deposit the AlO layer. Gas flow rate 300-500 sccm, target current 180-200 A, target-substrate distance 120-220 mm, vacuum degree 0.8-1.0 Pa, bias voltage 60-80 V, co-deposit AlO layer 0.3-0.4 μm; start N2 gas again, turn on TiAl target, turn off aluminum alloy target and stop O2 gas flow to deposit TiAlN surface layer, target current 150-250 A, coil current 1.0-2.0 A, target-substrate distance 120-220 mm, N2 gas flow rate 1000-1200 sccm, vacuum degree 2.0-3.5 Pa, deposit 0.5-0.6 μm under 80-100 V bias voltage.

[0043] Testing revealed that the coating exhibited a scratch adhesion strength of 50-65 N and a nano-indentation hardness of 28-32 GPa. Comparison with Example 1 showed that the absence of the gradient transition layer had virtually no impact on hardness, but did reduce adhesion, indicating that the gradient transition layer process of this invention has a positive effect on coating performance.

[0044] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for low-temperature preparation of AlO2-containing materials using arc plasma x The hard coating process is characterized by: The process includes the following steps: Step 1: Pre-treatment of the substrate surface. Use organic solvent to ultrasonically clean the workpiece to remove stains from the surface and then blow dry it for later use. Step 2: Ar ion etching. Argon gas is introduced and ignition discharge is initiated to form Ar ions. The ions bombard the workpiece surface, remove surface impurities, and enhance the adhesion between the film and the substrate. Step 3: TiAlN, AlO x The deposition of the TiAlN composite coating involves: opening the TiAl target and introducing N2 gas to deposit the TiAlN underlayer; opening the aluminum alloy target and introducing N2 and O2 gas with gradually varying flow rates to deposit the AlON transition layer; and opening the aluminum alloy target and introducing O2 gas to deposit AlO. x The first layer is deposited, followed by an AlON transition layer and a TiAlN surface layer.

2. The process for preparing AlOx-containing hard coatings at low temperature using arc plasma according to claim 1, characterized in that: The ultrasonic cleaning of the substrate surface can also be performed using deionized water.

3. The process for preparing AlOx-containing hard coatings at low temperature using arc plasma according to claim 1, characterized in that: The final coating consists of a TiAlN underlayer, an AlON transition layer, and an AlO layer. x It consists of an intermediate layer, an AlON transition layer, and a TiAlN surface layer. The AlON transition layer contains two layers, which are located in AlO. x Both sides of the middle layer.

4. The process for preparing AlOx-containing hard coatings at low temperature using arc plasma according to claim 1, characterized in that: The specific process parameters for the Ar ion etching are: temperature 500-600℃, argon flow rate 100-300 sccm, pulse bias voltage 80-150V, ion etching current 120-150A, and etching time 60-90min.

5. The process for preparing AlOx-containing hard coatings at low temperature using arc plasma according to claim 1, characterized in that: The specific process for depositing the TiAlN underlayer in step three is as follows: target current 150-250A, coil current 1.0-2.0A, target-substrate distance 120-220mm, N2 gas flow rate 1000-1200sccm, vacuum degree 2.0-3.5Pa. First, a TiAlN layer of 0.8-1.0μm is deposited under a bias voltage of 30-50V, and then a TiAlN layer of 0.4-0.6μm is deposited under a bias voltage of 80-100V. The TiAl target is then turned off.

6. The process for preparing AlOx-containing hard coatings at low temperature using arc plasma according to claim 1, characterized in that: The specific process for depositing the AlON transition layer in step three is as follows: target current 160-180A, target-substrate distance 120-220mm, N2 gas flow rate gradually decreasing from 1000-1200sccm to 50-100sccm, O2 gas flow rate gradually increasing from 50-100sccm to 200-400sccm, bias voltage 60-80V, and the entire process takes only 3-5 minutes.

7. The process for preparing AlOx-containing hard coatings at low temperature using arc plasma according to claim 1, characterized in that: In step three, AlO is deposited. x The specific process for the layer is as follows: stop the N2 gas supply, deposit an AlO layer, further increase the O2 gas flow rate to 300-500 sccm, target current 180-200 A, target-substrate distance 120-220 mm, vacuum degree 0.8-1.0 Pa, bias voltage 60-80 V, and co-deposit an AlO layer of 0.3-0.4 μm.

8. The process for preparing AlOx-containing hard coatings at low temperature using arc plasma according to claim 1, characterized in that: The specific process for re-depositing the AlON transition layer in step three is as follows: N2 gas is introduced, target current is 160-180A, target-substrate distance is 120-220mm, N2 gas flow rate is gradually increased from 50-100sccm to 1000-1200sccm, O2 gas flow rate is gradually decreased from 200-400sccm to 50-100sccm, bias voltage is 60-80V, and deposition takes 3-5 minutes.

9. The process for preparing AlOx-containing hard coatings at low temperature using arc plasma according to claim 1, characterized in that: The specific process for depositing the TiAlN surface layer in step three is as follows: turn on the TiAl target, turn off the aluminum alloy target and stop the O2 gas supply, target current 150-250A, coil current 1.0-2.0A, target-substrate distance 120-220mm, N2 gas flow rate 1000-1200sccm, vacuum degree 2.0-3.5Pa, and deposit 0.5-0.6μm under a bias voltage of 80-100V.

Images