Cutting tool and machining method for a titanium alloy material

Abstract

The application discloses a kind of titanium alloy material cutting tool and processing method, including the following steps: hard phase WC, binder phase and additive are proportioned, ball milling, spray drying, press forming are obtained tool blank, after using segmented sintering treatment, mechanical processing is formed to obtain cutting tool, electromagnetic coupling strengthening treatment and surface coating layer treatment are sequentially carried out, form TiN layer, CrAlN layer, CrAlSiN layer and CrAlBN layer;Titanium-based alloy powder can be added in binder phase in the application, can enhance the high-temperature strength, heat resistance and lightweight characteristics of cutting tool;Modified CeO2 can improve the uniformity of tool microstructure, interface bonding force and oxidation resistance, so as to improve the density and crack resistance;Electromagnetic coupling strengthening treatment and multilayer coating deposition treatment are carried out on cutting tool, which can significantly improve the hardness, wear resistance, oxidation resistance and high-temperature resistance of the surface of the tool, and effectively prevent the coating from peeling off.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of titanium alloy cutting tools, in particular to a cutting tool of titanium alloy material and a machining method. BACKGROUND

[0002] In the field of mechanical processing, cutting tools as key tools in processing technology, their performance directly affects the machining precision, efficiency and surface quality of workpiece. With the wide application of high-strength materials and difficult-to-machine alloys in the fields of aerospace, automobile manufacturing and other fields, the traditional cutting tool materials gradually expose the problems of insufficient hardness, lack of toughness and poor thermal fatigue resistance under high temperature and high speed cutting conditions, resulting in short tool life and low cutting efficiency, which is difficult to meet the demand of modern industry for high efficiency and precision machining. In order to solve these problems, the improvement of tool material has become the key research direction. Among them, by introducing titanium alloy and other lightweight high-strength materials into the tool substrate, combined with its excellent specific strength and heat resistance, the comprehensive mechanical properties of the tool can be effectively improved. However, the introduction of titanium alloy also faces a series of technical bottlenecks, for example, the insufficient bonding force between titanium alloy and hard phase and binder phase will cause the problem of uneven microstructure and strength reduction of tool substrate; in addition, the existing technology lacks effective solutions in the synergistic optimization of titanium alloy and other functional additives, which is difficult to comprehensively improve the hardness, toughness and processing thermal stability of the tool.

[0003] Therefore, the prior art has defects and needs to be improved. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a cutting tool of titanium alloy material and a machining method for improving the hardness and toughness of the cutting tool and improving the thermal stability of the product.

[0005] To achieve this purpose, the present application adopts the following technical solutions:

[0006] A cutting tool machining method of titanium alloy material, comprising the following steps:

[0007] S1, the raw materials are prepared according to the following weight percentage:

[0008] Hard phase WC 75%-80%;

[0009] Binder phase composed of metal cobalt and titanium-based alloy powder 10%-15%, wherein the metal cobalt accounts for 50%-60% of the total amount of the binder phase, the titanium-based alloy powder accounts for 40%-50%, and the chemical composition of the titanium-based alloy powder is: titanium 68%-75%, aluminum 15%-25%, vanadium 4%-8%;

[0010] Additives 5%-8%, the additives are composed of: TiO2 2%-3%, TiB2 1%-2%, and modified CeO2 2%-3%;

[0011] S2. The hard phase, binder phase and additives are fed into a ball mill according to the raw material ratio and ball milled. After spray drying, a mixed powder is obtained.

[0012] S3. Press the mixed powder into shape to obtain a tool blank;

[0013] S4. The tool blank is sintered using a segmented sintering method.

[0014] S5. The sintered tool blank is mechanically cut to obtain the cutting tool.

[0015] S6. The cutting tool is subjected to electromagnetic coupling strengthening treatment and surface coating treatment in sequence to form TiN layer, CrAlN layer, CrAlSiN layer and CrAlBN layer on the surface of the cutting tool in sequence.

[0016] Using the above technical solution, the specific process of electromagnetic coupling enhancement treatment in step S6 is as follows:

[0017] After ultrasonic cleaning, the cutting tool is loaded into an electromagnetic coupling treatment device. The electromagnetic field frequency is set to 2MHz and the magnetic field strength to 150mT. Then, high-purity nitrogen gas is introduced, with the gas flow rate controlled at 60-80L / min. The temperature is then gradually increased to 600-800℃ at a rate of 10-15℃ / min, thereby decomposing the nitrogen gas into high-energy active nitrogen ions and forming a TiN layer on the surface of the cutting tool.

[0018] Using the above technical solutions, the specific process of surface coating treatment in step S6 is as follows:

[0019] In an Ar atmosphere, the cutting tool was subjected to ion bombardment treatment with a substrate bias of -180V for 10-20 min. Then, high-purity N2 was introduced with a flow rate of 40-50 sccm and a substrate bias of -170V was applied. Cr and Al targets were sputtered with sputtering powers of 140W and 130W, respectively, for 60 min to obtain a CrAlN layer.

[0020] High-purity N2 was added to the Ar gas supply, with Ar and N2 flow rates of 40 sccm and 10 sccm, respectively. The target material was adjusted to Cr. 0.35 Al 0.45 Si 0.10 The alloy target was sputtered with a power of 150W, a substrate bias of -100V, and a deposition time of 30min to obtain a CrAlSiN layer.

[0021] Next, high-purity B2H6 was introduced into an Ar and N2 atmosphere at a flow rate of 10-20 sccm, with Cr as the target material.0.30 Al 0.60 B 0.10 The sputtering power is 150 W, the substrate bias is -100 V, and the deposition time is 30 min to obtain a CrAlBN layer.

[0022] The modification process of the modified CeO2 is as follows:

[0023] CeO2 particles with a particle size of 100-200 nm are placed in an ultrasonic cleaning device, a mixed solution of deionized water and anhydrous ethanol with a volume ratio of 1:1 is added, and the particles are cleaned for 10-15 min, then filtered with filter paper, and the CeO2 particles are taken out. The CeO2 particles are then placed in an oven at 60-80°C and dried for 3-5 h to ensure that there is no residual liquid on the surface of the CeO2 particles.

[0024] The CeO2 particles are then placed in a vacuum plasma treatment device, the cavity of the vacuum plasma treatment device is vacuumized to a vacuum degree of less than 0.001 Pa, high-purity Ar is then introduced into the cavity, the pressure in the cavity is maintained at 20-50 Pa, the radio frequency plasma source is started, the frequency is 13.56 MHz, and the power is 200-400 W, so that the CeO2 particles are uniformly bombarded in the plasma environment, and the treatment time is 3-5 min.

[0025] The thickness of the TiN layer is 1-4 μm.

[0026] The thickness of the CrAlN layer is 0.5-0.7 μm, the thickness of the CrAlSiN layer is 0.6-0.8 μm, and the thickness of the CrAlBN layer is 0.7-0.9 μm.

[0027] In step S2, ethanol is added as a ball milling medium during ball milling of the raw material, and 0.5 wt% of polyethylene glycol is added as a forming agent for ball milling, the ball powder ratio is 10:1, and the ball milling time is 12-24 h.

[0028] In step S3, the mixed powder is first subjected to preliminary pressing using a cold isostatic pressing device, the pressing pressure is 200-300 MPa, and then the preliminarily pressed tool blank is placed in a hot isostatic pressing device for high-temperature compaction treatment, the temperature is controlled at 900-1100°C, the pressure is 50-100 MPa, and the holding time is 1-2 h.

[0029] In step S4, the segmented sintering method is as follows:

[0030] S41, a dewaxing stage: after vacuumizing the sintering furnace to 20-50 Pa, hydrogen is introduced, the furnace temperature is raised to 350-400 DEG C at a heating rate of 35-45 DEG C / min, and the temperature is kept for 4-6 h;

[0031] S42, a vacuum sintering stage: the furnace temperature is raised to 1250 DEG C at a heating rate of 20-25 DEG C / min, and the temperature is kept for 50-60 min, then the furnace temperature is raised to 1350 DEG C at a heating rate of 8-10 DEG C / min, and the temperature is kept for 70-90 min;

[0032] S43, a pressure sintering stage: after the vacuum sintering is completed, argon is introduced into the furnace, the pressure in the furnace is raised to 50-100 mbar, and the furnace temperature is raised to 1450-1500 DEG C at a heating rate of 5 DEG C / min, and the temperature is kept for 30-60 min;

[0033] S44, a cooling stage: after the heating is stopped, the furnace temperature is lowered to 1000 DEG C at a cooling rate of 12-25 DEG C / min, 950-980 mbar argon is introduced for forced cooling at the temperature, and the cooling rate is controlled at 10-15 DEG C / min until the furnace temperature is lower than 100 DEG C, and the cutter blank is taken out.

[0034] The technical scheme also provides a cutting tool of a titanium alloy material, which is prepared by using the cutting tool machining method of the titanium alloy material.

[0035] Compared with the prior art, the application has the following beneficial effects:

[0036] The present application can enhance the high-temperature strength and heat resistance of the cutting tool by adding titanium-based alloy powder in the binder phase, avoid the problem of binder phase softening failure in high-temperature cutting, and at the same time, give the tool light weight and high strength characteristics, and improve the cutting efficiency; secondly, the addition of modified CeO2 improves the uniformity of the microstructure of the material and the interfacial bonding force, thereby improving the densification effect of sintering, so that there is no stress concentration point in the tool, thereby significantly enhancing the crack resistance; in addition, the antioxidant effect of CeO2 can improve the wear resistance and service life of the tool; the introduction of the pressure sintering stage in the sintering process can effectively eliminate the micropores in the material, significantly improve the density, mechanical strength and toughness of the material, and optimize the microstructure, so that the tool shows better heat resistance and fatigue resistance in high-temperature cutting; the electromagnetic coupling strengthening treatment can generate a dense TiN layer on the surface of the tool, greatly improve the surface hardness and wear resistance of the tool, and at the same time, enhance the oxidation resistance, resist thermal fatigue and oxidation wear in high-temperature cutting; the multilayer coating treatment can form a gradient-optimized structure by depositing CrAlN, CrAlSiN and CrAlBN coatings layer by layer, which takes into account hardness, wear resistance, toughness and high-temperature resistance, not only reduces the friction coefficient, but also significantly improves the bonding force between the coating and the substrate, avoiding the problem of coating peeling. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below with reference to examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application. In addition, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" described below means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms is not necessarily directed to the same embodiment or example. Moreover, the technical features involved in each embodiment of the present application can be combined with each other as long as there is no conflict.

[0038] The present application provides a cutting tool machining method of a titanium alloy material, comprising the following steps:

[0039] S1, the raw materials are proportioned according to the following weight percentage:

[0040] The hard phase WC is 75%-80%, and the hard phase WC accounts for 75%-80%, which is the strengthening phase of the cutting tool, and its high hardness and wear resistance can effectively resist the strong friction and wear force generated during cutting.

[0041] The binder phase is composed of 10%-15% of metal cobalt and titanium-based alloy powder, wherein the metal cobalt accounts for 50%-60% of the total amount of the binder phase, and the titanium-based alloy powder accounts for 40%-50%, and the chemical composition of the titanium-based alloy powder is: titanium 68%-75%, aluminum 15%-25%, and vanadium 4%-8%; the binder phase is composed of metal cobalt and titanium-based alloy powder, wherein the proportion of the metal cobalt is 50%-60%, which can ensure good wettability and overall toughness of the material, and the titanium-based alloy powder can improve the high-temperature stability of the cutting tool due to its excellent specific strength and heat resistance; the content of titanium in the titanium-based alloy is 68%-75%, which can provide the lightweight and high-strength characteristics of the substrate, the content of aluminum is 15%-25%, which can improve the oxidation resistance and high-temperature resistance of the alloy, and the content of vanadium is 4%-8%, which can refine the grain structure and thus improve the comprehensive mechanical properties of the material;

[0042] The additive is 5%-8% and is composed of: TiO2 2%-3%, TiB2 1%-2%, and modified CeO2 2%-3%; TiO2 can provide good wear resistance and thermal stability, TiB2 can enhance the fatigue resistance of the tool due to its extremely high hardness and corrosion resistance, and modified CeO2 can greatly improve its surface activity after plasma modification, so that it can better combine with other components, thereby improving the microstructure uniformity and high-temperature performance of the material.

[0043] S2, the hard phase, the binder phase and the additive are put into a ball mill according to the raw material ratio for ball milling, and a mixed powder is obtained after spray drying; in the ball milling process, the hard phase WC and the binder phase metal powder are fully mixed by mechanical energy, so that a uniform contact interface is formed between different components, local enrichment of a single component is avoided, and the densification and uniformity of the material during sintering are ensured.

[0044] S3, the mixed powder is pressed into a tool blank;

[0045] S4, the tool blank is sintered by a segmented sintering method;

[0046] S5, the sintered tool blank is mechanically cut and processed to obtain a cutting tool;

[0047] S6, the cutting tool is sequentially subjected to electromagnetic coupling strengthening treatment and surface coating treatment to sequentially form TiN layer, CrAlN layer, CrAlSiN layer and CrAlBN layer on the surface of the cutting tool. The electromagnetic coupling strengthening treatment can introduce active nitrogen ions on the surface of the cutting tool by using high-frequency electromagnetic field to form a dense TiN layer, which not only improves the hardness and wear resistance of the surface of the cutting tool, but also significantly enhances the oxidation resistance, especially in high-temperature cutting environment, which can effectively resist thermal fatigue and oxidation wear; and the subsequent multi-layer coating treatment can further improve the comprehensive performance of the cutting tool by depositing CrAlN, CrAlSiN and CrAlBN coating layer by layer; specifically, the CrAlN layer has excellent wear resistance and high-temperature oxidation resistance, which can provide basic protection for the tool; the CrAlSiN layer can form a dense nano-composite structure by adding Si element, which can greatly improve the hardness and heat resistance of the coating; the CrAlBN layer can provide additional impact resistance and lubrication properties due to its boron content, thereby reducing the friction coefficient during cutting. In this way, this layer-by-layer deposition structure not only solves the brittleness problem of single coating, but also improves the adhesion between the coating and the substrate through the gradient transition between the coating layers, avoiding coating peeling.

[0048] Further, in step S6, the specific process of electromagnetic coupling strengthening treatment is as follows: after the cutting tool is cleaned by ultrasonic wave, it is loaded into the electromagnetic coupling treatment equipment, the frequency of the electromagnetic field is set to 2 MHz, the magnetic field strength is 150 mT, then high-purity nitrogen gas is introduced, the gas flow is controlled at 60-80 L / min, then the temperature is gradually increased to 600-800℃ at a rate of 10-15℃ / min, so that the nitrogen gas is decomposed into active nitrogen ions in high-energy state, and a TiN layer is formed on the surface of the cutting tool. The cutting tool is placed in the electromagnetic coupling treatment equipment, and the frequency of the electromagnetic field is set to 2 MHz and the magnetic field strength is 150 mT, so that the high-energy electromagnetic field can be excited to decompose the nitrogen gas into active nitrogen ions in high-energy state, the nitrogen gas flow is controlled at 60-80 L / min to ensure the stability of the atmosphere and maintain the uniform distribution of ion concentration, avoiding the problem of uneven ion implantation; then, the temperature is gradually increased to 600-800℃ at a rate of 10-15℃ / min, at this temperature range, the surface atoms of the cutting tool substrate have enough energy to react with nitrogen ions, thereby forming a dense TiN coating. The TiN layer can not only significantly improve the hardness of the surface of the cutting tool, but also enhance its oxidation resistance and high-temperature resistance, meeting the performance requirements of the cutting tool under extreme cutting conditions.

[0049] Further, in step S6, the specific process of the surface plating layer treatment is: under Ar atmosphere, ion bombardment treatment is performed on the cutting tool under the condition that the substrate bias is -180 V, the bombardment time is 10-20 min, then high-purity N2 is introduced, the flow is controlled at 40-50 sccm, the substrate bias is -170 V, the Cr and Al targets are started, the sputtering power is 140 W and 130 W respectively, and the deposition time is 60 min, so as to obtain a CrAlN layer;

[0050] On the basis of introducing Ar, high-purity N2 is added, the flow rates of Ar and N2 are 40 sccm and 10 sccm respectively, the target is adjusted to be an alloy target of Cr 0.35 Al 0.45 Si 0.10 , the sputtering power is 150 W, the substrate bias is -100 V, and the deposition time is 30 min, so as to obtain a CrAlSiN layer;

[0051] Then, high-purity B2H6 is introduced in Ar and N2 atmosphere, the gas flow is 10-20 sccm, the target is Cr 0.30 Al 0.60 B 0.10 , the sputtering power is 150 W, the substrate bias is -100 V, and the deposition time is 30 min, so as to obtain a CrAlBN layer.

[0052] Firstly, the substrate is subjected to ion bombardment under Ar atmosphere with a bias of -180 V, which can remove residual impurities and oxide layers on the surface of the tool and induce atomic rearrangement on the surface of the substrate, thereby improving the adhesion between the coating and the substrate; then, by adjusting the flow rate of high-purity Ar to 40-50 sccm, applying a substrate bias of -170 V, and starting the sputtering deposition of Cr and Al targets, a dense CrAlN layer is formed under the conditions of sputtering power of 140 W and 130 W; the coating is mainly composed of chemical bonds of Cr and Al, and the high-temperature oxidation resistance and wear resistance of the coating can provide basic protection for the tool; next, when depositing the second layer of coating, high-purity N2 is added in Ar, and the target is adjusted to be an alloy target of Cr 0.35 Al 0.45 Si 0.10 , the substrate bias is -100 V, so that Si elements are introduced into the coating, and the nano-composite structure formed by Si can improve the hardness and wear resistance of the coating and enhance its high-temperature stability; when depositing the third layer, high-purity B2H6 is introduced and a target of Cr 0.30 Al 0.60 B 0.10The target material is used to form a CrAlBN layer under the conditions of a sputtering power of 150 W and a substrate bias of -100 V, the layer can reduce the cutting friction coefficient and improve the toughness and thermal fatigue resistance of the cutting tool due to the lubricating properties and impact resistance of boron, the layer-by-layer deposition method realizes the balance of hardness, wear resistance, toughness and bonding force through gradient optimization of the coating composition, and effectively enhances the comprehensive performance of the cutting tool in complex cutting environments.

[0053] Further, the modification treatment process of the modified CeO2 is as follows: the CeO2 particles with a particle size of 100-200 nm are placed in an ultrasonic cleaning device, a mixed solution of deionized water and anhydrous ethanol with a volume ratio of 1:1 is added, and the particles are cleaned for 10-15 min, then filtered with filter paper, and the CeO2 particles are taken out, and then the CeO2 particles are placed in an oven at 60-80℃ and dried for 3-5 h to ensure that the surface of the CeO2 particles is free of residual liquid, and then the CeO2 particles are placed in a vacuum plasma treatment device, the cavity of the vacuum plasma treatment device is vacuumized to a vacuum degree of less than 0.001 Pa, high-purity Ar is introduced into the cavity, the pressure in the cavity is maintained at 20-50 Pa, the radio frequency plasma source is started, the frequency is 13.56 MHz, and the power is 200-400 W, and the CeO2 particles are uniformly bombarded in the plasma environment for 3-5 min. The Ar ions are excited by the radio frequency plasma source at a frequency of 13.56 MHz and a power of 200-400 W, which interact with the surface of the CeO2 particles, break the chemical bonds on the surface of the particles, remove the surface inert layer, and introduce active sites, thereby improving the chemical reactivity and dispersibility of the particles. The treatment time is controlled within 3-5 min to realize uniform modification of the surface of the particles, while avoiding excessive bombardment that changes the size and morphology of the particles.

[0054] Further, the thickness of the TiN layer is 1-4 microns.

[0055] Further, the thickness of the CrAlN layer is 0.5-0.7 microns, the thickness of the CrAlSiN layer is 0.6-0.8 microns, and the thickness of the CrAlBN layer is 0.7-0.9 microns.

[0056] Further, in step S2, ethanol is added as a ball milling medium during the ball milling process of the raw materials, and 0.5wt% of polyethylene glycol is added as a forming agent for ball milling, the ball powder ratio is 10:1, and the ball milling time is 12-24h. Ethanol as a ball milling medium can reduce the friction and adhesion phenomenon in the ball milling process through its liquid properties, effectively reducing the risk of particle agglomeration, and its volatility can be quickly removed after spray drying without leaving impurities; the addition of polyethylene glycol can improve the lubricity and adhesion of the particles to form a more uniform particle distribution during the ball milling process, and act as a binder to enhance the flowability and pressing performance of the powder during the subsequent forming process; the ball powder ratio is set to 10:1, which can provide sufficient grinding energy while avoiding excessive particle breakage or ball milling efficiency due to high ratio.

[0057] Further, in step S3, the mixed powder is first subjected to preliminary pressing using a cold isostatic pressing device, the pressing pressure is 200-300MPa, and then the preliminary pressed tool blank is placed in a hot isostatic pressing device for high temperature compaction treatment, the temperature is controlled at 900-1100℃, the pressure is 50-100MPa, and the holding time is 1-2h. Cold isostatic pressing with a pressure of 200-300MPa acts on the mixed powder to form a preliminary densification blank in a low temperature environment, ensuring the initial contact and bonding between particles while maintaining the uniformity of the overall shape; through cold isostatic pressing, the large pores between the powder can be reduced without introducing high temperature stress, and a more stable structural foundation is provided for subsequent high temperature treatment; then in the hot isostatic pressing stage, the temperature is controlled at 900-1100℃, the pressure is 50-100MPa, and the holding time is 1-2h, which can realize the recrystallization of the powder and the complete densification between the particles under the combined action of high temperature and high pressure. High temperature can promote atomic diffusion and interfacial reaction on the surface of the particles, so that the bonding force between the particles is enhanced, and at the same time the residual micropores are eliminated, improving the mechanical properties of the material.

[0058] Further, in step S4, the method of segmented sintering is as follows:

[0059] S41, dewaxing stage: after vacuumizing the sintering furnace to 20-50Pa, hydrogen is introduced, the furnace temperature is raised to 350-400℃ at a heating rate of 35-45℃ / min, and the holding time is 4-6h;

[0060] S42, vacuum sintering stage: the furnace temperature is raised to 1250℃ at a heating rate of 20-25℃ / min, and the holding time is 50-60min, then the furnace temperature is raised to 1350℃ at a heating rate of 8-10℃ / min, and the holding time is 70-90min;

[0061] S43, pressure sintering stage: after vacuum sintering is completed, argon is introduced into the furnace, the pressure in the furnace is increased to 50-100 mbar, and the furnace temperature is increased to 1450-1500 DEG C at a heating rate of 5 DEG C / min, and maintained for 30-60 min;

[0062] S44, cooling stage: after stopping heating, the furnace temperature is decreased to 1000 DEG C at a cooling rate of 12-25 DEG C / min, 950-980 mbar of argon is introduced for forced cooling, and the cooling rate is controlled at 10-15 DEG C / min until the furnace temperature is lower than 100 DEG C, and the tool blank is taken out. The wax removal stage can ensure complete decomposition and volatilization of the organic forming agent in a low-oxygen environment by vacuumizing the sintering furnace to 20-50 Pa and introducing hydrogen, avoiding the formation of pores or carbides due to residual organic matter in the subsequent high-temperature stage; the heating rate of 35-45 DEG C / min ensures stable dewaxing process without introducing excessive thermal stress, and the holding time of 4-6 h ensures complete decomposition of the wax; the preliminary heating of 20-25 DEG C / min to 1250 DEG C in the vacuum sintering stage and the holding time of 50-60 min can promote atomic diffusion and preliminary bonding on the surface of the particles, thereby forming a uniform matrix microstructure; then, the slow heating of 8-10 DEG C / min to 1350 DEG C and the holding time of 70-90 min can realize further diffusion bonding and densification between the particles, while inhibiting particle coarsening and stress concentration in the material; the pressure sintering stage can utilize the synergistic effect of high temperature and high pressure to compact the material by introducing argon and increasing the pressure in the furnace to 50-100 mbar, and then increasing the temperature to 1450-1500 DEG C at a heating rate of 5 DEG C / min, thereby eliminating residual pores and forming a high-strength dense structure; the cooling stage can stabilize the microstructure while avoiding the generation of thermal stress cracks, and gradually decreases to 1000 DEG C at a cooling rate of 12-25 DEG C / min, and then forced cooling is performed under the protection of 950-980 mbar of argon, which can ensure the structural stability and dimensional accuracy; finally, the cooling rate is decreased to room temperature at a rate of 10-15 DEG C / min, which can avoid the accumulation of thermal stress or the formation of micro defects due to rapid cooling. The entire staged sintering process is precisely controlled, which ensures that the microstructure of the material is dense and the performance is excellent, and can meet the use requirements of high-performance cutting tools.

[0063] Example 1

[0064] The embodiment 1 of the present application provides a machining method of a cutting tool of a titanium alloy material, comprising the following steps:

[0065] S1, the raw materials are prepared according to the following weight percentage:

[0066] Hard phase WC 80%;

[0067] The binder phase 15% is composed of metal cobalt and titanium-based alloy powder, wherein the metal cobalt accounts for 60% of the total amount of the binder phase, and the titanium-based alloy powder accounts for 40%; the titanium-based alloy powder has a chemical composition of: titanium 75%, aluminum 20%, and vanadium 5%;

[0068] The additive 5% is composed of: TiO2 2%, TiB2 1%, and modified CeO2 2%;

[0069] The modification process of the modified CeO2 is as follows:

[0070] CeO2 particles with a particle size of 200 nm are placed in an ultrasonic cleaning device, a mixed solution of deionized water and anhydrous ethanol with a volume ratio of 1:1 is added, and the particles are cleaned for 15 min, then filtered with filter paper, and the CeO2 particles are taken out, and then the CeO2 particles are placed in an oven at 80°C and dried for 5 h to ensure that there is no residual liquid on the surface of the CeO2 particles.

[0071] Then the CeO2 particles are placed in a vacuum plasma treatment device, the cavity of the vacuum plasma treatment device is vacuumized to a vacuum degree of less than 0.001 Pa, high-purity Ar is then introduced into the cavity, the pressure in the cavity is maintained at 50 Pa, the radio frequency plasma source is started, the frequency is 13.56 MHz, and the power is 400 W, so that the CeO2 particles are uniformly bombarded in the plasma environment, and the treatment time is 5 min.

[0072] S2, the hard phase, the binder phase and the additive are put into a ball mill according to the raw material ratio for ball milling, ethanol is added as a ball milling medium during the ball milling of the raw materials, and 0.5wt% of polyethylene glycol is added as a forming agent for ball milling, the ball powder ratio is 10:1, the ball milling time is 24h, and the mixed powder is obtained after spray drying;

[0073] S3, the mixed powder is pressed into a tool blank, specifically: first, the mixed powder is preliminarily pressed by a cold isostatic pressing device, the pressing pressure is 300MPa, then the preliminarily pressed tool blank is placed in a hot isostatic pressing device for high-temperature compaction treatment, the temperature is controlled at 9000°C, the pressure is 100MPa, and the holding time is 2h;

[0074] S4, the tool blank is sintered by a segmented sintering method, and the segmented sintering method is as follows:

[0075] S41, dewaxing stage: after the sintering furnace is vacuumized to 50Pa, hydrogen is introduced, the furnace temperature is raised to 400°C at a heating rate of 45°C / min, and the temperature is maintained for 6h;

[0076] S42, vacuum sintering stage: the furnace temperature is raised from 25℃ / min to 1250℃, and the temperature is kept for 60min, then the furnace temperature is raised to 1350℃ at a rate of 10℃ / min, and the temperature is kept for 90min;

[0077] S43, pressure sintering stage: after vacuum sintering, argon is introduced into the furnace to increase the pressure to 100mbar, and the furnace temperature is raised to 1500℃ at a rate of 5℃ / min, and kept for 60min;

[0078] S44, cooling stage: after stopping heating, the furnace temperature is lowered to 1000℃ at a rate of 25℃ / min, and 980mbar of argon is introduced for forced cooling, and the temperature is lowered at a rate of 15℃ / min until the furnace temperature is lower than 100℃, and the tool blank is taken out;

[0079] S5, the sintered tool blank is mechanically cut to obtain a cutting tool;

[0080] S6, the cutting tool is subjected to electromagnetic coupling strengthening treatment and surface coating treatment in sequence to form TiN layer, CrAlN layer, CrAlSiN layer and CrAlBN layer on the surface of the cutting tool in sequence;

[0081] The thickness of the TiN layer is 1μm, the thickness of the CrAlN layer is 0.5μm, the thickness of the CrAlSiN layer is 0.6μm, and the thickness of the CrAlBN layer is 0.7μm;

[0082] The specific process of electromagnetic coupling strengthening treatment is as follows:

[0083] After the cutting tool is cleaned by ultrasonic wave, it is loaded into the electromagnetic coupling treatment equipment, the frequency of the electromagnetic field is set to 2MHz, the magnetic field strength is 150mT, then high-purity nitrogen gas is introduced, the gas flow is controlled at 60L / min, then the temperature is gradually raised to 800℃ at a rate of 15℃ / min, so that the nitrogen gas is decomposed into high-energy active nitrogen ions, and a TiN layer is formed on the surface of the cutting tool;

[0084] The specific process of surface coating treatment is as follows:

[0085] In Ar atmosphere, the cutting tool is subjected to ion bombardment treatment under the condition of substrate bias-180V, the bombardment time is 20min, then high-purity N2 is introduced, the flow is controlled at 50sccm, and the substrate bias-170V is applied, the Cr and Al targets are started, the sputtering power is 140W and 130W respectively, and the deposition time is 60min, to obtain a CrAlN layer;

[0086] On the basis of Ar gas, high-purity N2 is added, the flow rates of Ar and N2 are 40 sccm and 10 sccm respectively, and the target material is adjusted to Cr 0.35 Al 0.45 Si 0.10 alloy target material, the sputtering power is 150 W, the substrate bias is -100 V, and the deposition time is 30 min, so as to obtain a CrAlSiN layer;

[0087] Then, high-purity B2H6 is introduced in an Ar and N2 atmosphere, the gas flow rate is 20 sccm, the target material is Cr 0.30 Al 0.60 B 0.10 , the sputtering power is 150 W, the substrate bias is -100 V, and the deposition time is 30 min, so as to obtain a CrAlBN layer.

[0088] Example 2

[0089] The embodiment 2 of the present application provides a cutting tool machining method of a titanium alloy material, comprising the following steps:

[0090] S1, raw materials are proportioned according to the following weight percentage:

[0091] a hard phase WC 77%;

[0092] a binder phase composed of metallic cobalt and titanium-based alloy powder, wherein the metallic cobalt accounts for 50% of the total amount of the binder phase, and the titanium-based alloy powder accounts for 50%; the titanium-based alloy powder has a chemical composition of: titanium 68%, aluminum 25%, and vanadium 7%;

[0093] additives 8%, which are composed of the following components: TiO2 3%, TiB2 2%, and modified CeO3 3%;

[0094] The modification treatment process of the modified CeO2 is as follows:

[0095] CeO2 particles with a particle size of 100 are placed in an ultrasonic cleaning device, a mixed solution of deionized water and anhydrous ethanol with a volume ratio of 1:1 is added, and the particles are cleaned for 15 min, then filtered with filter paper, and the CeO2 particles are taken out, and then the CeO2 particles are placed in an oven at 60°C and dried for 3 h to ensure that the surface of the CeO2 particles is free of residual liquid;

[0096] Then, the CeO2 particles are placed in a vacuum plasma treatment device, the cavity of the vacuum plasma treatment device is vacuumized to a vacuum degree of less than 0.001 Pa, high-purity Ar is introduced into the cavity, the pressure in the cavity is maintained at 20 Pa, a radio frequency plasma source is started, the frequency is 13.56 MHz, the power is 200 W, the CeO2 particles are uniformly bombarded in the plasma environment, and the treatment time is 3 min.

[0097] S2, the hard phase, the binder phase and the additives are put into a ball mill according to the raw material ratio for ball milling, ethanol is added as a ball milling medium during the ball milling of the raw materials, and 0.5wt% of polyethylene glycol is added as a forming agent for ball milling, the ball powder ratio is 10:1, the ball milling time is 12h, and the mixed powder is obtained after spray drying;

[0098] S3, the mixed powder is pressed into a tool blank, specifically: first, the mixed powder is preliminarily pressed by a cold isostatic pressing device, the pressing pressure is 200MPa, then the preliminarily pressed tool blank is put into a hot isostatic pressing device for high-temperature compaction treatment, the temperature is controlled at 1100℃, the pressure is 100MPa, and the holding time is 2h;

[0099] S4, the tool blank is sintered by a segmented sintering method, and the segmented sintering method is specifically:

[0100] S41, dewaxing stage: after the sintering furnace is vacuumized to 20Pa, hydrogen is introduced, the furnace temperature is raised to 350-℃ at a heating rate of 35℃ / min, and the temperature is kept for 4h;

[0101] S42, vacuum sintering stage: the furnace temperature is raised to 1250℃ at a heating rate of 20℃ / min, and kept for 50min, then the furnace temperature is raised to 1350℃ at a heating rate of 8℃ / min, and kept for 70min;

[0102] S43, pressure sintering stage: after the vacuum sintering is completed, argon is introduced into the furnace, the pressure in the furnace is raised to 50mbar, and the furnace temperature is raised to 1450℃ at a heating rate of 5℃ / min, and kept for 30min;

[0103] S44, cooling stage: after stopping heating, the furnace temperature is lowered to 1000℃ at a cooling rate of 12℃ / min, 950mbar of argon is introduced for forced cooling at this temperature, and the cooling rate is controlled at 10℃ / min until the furnace temperature is lower than 100℃, and the tool blank is taken out;

[0104] S5, the sintered tool blank is mechanically cut and processed to obtain a cutting tool;

[0105] S6, the cutting tool is sequentially subjected to electromagnetic coupling strengthening treatment and surface coating treatment to form TiN layer, CrAlN layer, CrAlSiN layer and CrAlBN layer on the surface of the cutting tool;

[0106] The thickness of the TiN layer is 4μm, the thickness of the CrAlN layer is 0.7μm, the thickness of the CrAlSiN layer is 0.8μm, and the thickness of the CrAlBN layer is 0.9μm.

[0107] The specific process of the electromagnetic coupling strengthening treatment is as follows:

[0108] After the cutting tool is cleaned by ultrasonic waves, the cutting tool is loaded into the electromagnetic coupling treatment equipment, the frequency of the electromagnetic field is set to 2 MHz, the magnetic field strength is 150 mT, then high-purity nitrogen gas is introduced, the gas flow is controlled at 60 L / min, then the temperature is gradually increased to 600 DEG C at a rate of 10 DEG C / min, so that the nitrogen gas is decomposed into active nitrogen ions in a high-energy state, and a TiN layer is formed on the surface of the cutting tool;

[0109] The specific process of the surface coating treatment is as follows:

[0110] In an Ar atmosphere, the cutting tool is subjected to ion bombardment treatment under the condition that the substrate bias is -180 V, the bombardment time is 20 min, then high-purity N2 is introduced, the flow is controlled at 40 sccm, and the substrate bias is -170 V, the Cr and Al targets are started, the sputtering power is 140 W and 130 W respectively, and the deposition time is 60 min, so as to obtain a CrAlN layer;

[0111] On the basis of introducing Ar gas, high-purity N2 is added, the flow rates of Ar and N2 are 40 sccm and 10 sccm respectively, the target material is adjusted to be an alloy target of Cr 0.35 Al 0.45 Si 0.10 , the sputtering power is 150 W, the substrate bias is -100 V, and the deposition time is 30 min, so as to obtain a CrAlSiN layer;

[0112] Then, high-purity B2H6 is introduced in an Ar and N2 atmosphere, the gas flow is 100 sccm, the target material is Cr 0.30 Al 0.60 B 0.10 , the sputtering power is 150 W, the substrate bias is -100 V, and the deposition time is 30 min, so as to obtain a CrAlBN layer.

[0113] Comparative Example 1

[0114] The cutting tool and machining method of the titanium alloy material of the comparative example 1 are different from those of the example 1 in that in the step S1, the binder phase only contains metal cobalt powder.

[0115] Comparative Example 2

[0116] The cutting tool and machining method of the titanium alloy material of the comparative example 2 are different from those of the example 1 in that in the step S1, the modified CeO2 is not contained in the additive.

[0117] Comparative Example 3

[0118] The cutting tool and machining method of the titanium alloy material of the present comparative example 3 are different from the example 1 in that, in step S4, there is no pressurized sintering stage in the sintering mode.

[0119] Comparative Example 4

[0120] The cutting tool and machining method of the titanium alloy material of the present comparative example 4 are different from the example 1 in that, in step S6, the cutting tool is not subjected to the electromagnetic coupling strengthening treatment.

[0121] Comparative Example 5

[0122] The cutting tool and machining method of the titanium alloy material of the present comparative example 5 are different from the example 1 in that, in step S6, the cutting tool is not subjected to the multi-layer coating treatment.

[0123] The above examples 1-2 and comparative examples 1-5 are subjected to experiments to verify or understand their performances, in the cutting tools of the titanium alloy materials prepared in the above examples 1-2 and comparative examples 1-6.

[0124]

[0125] Table 1: Performance test comparison table of the cutting tools of the titanium alloy materials of the examples and comparative examples

[0126] According to the above table 1, in the cutting tools of the titanium alloy materials prepared in the examples 1 and 2, the titanium-based alloy powder added in the binder phase enhances the high-temperature strength and heat resistance of the cutting tools, avoids the problem of softening failure of the binder phase in high-temperature cutting, and at the same time, gives the cutting tools the characteristics of lightweight and high strength, and improves the cutting efficiency; secondly, the addition of modified CeO2improves the microstructure uniformity and interfacial bonding force of the material, thereby improving the densification effect of sintering, so that there is no stress concentration point in the cutting tool, thereby significantly enhancing the crack resistance; in addition, the antioxidant effect of CeO2can improve the wear resistance and service life of the cutting tool; the introduction of the pressurized sintering stage in the sintering process can effectively eliminate the micro-pores in the material, significantly improve the density, mechanical strength and toughness of the material, and optimize the microstructure, so that the cutting tool exhibits better heat resistance and fatigue resistance in high-temperature cutting; the electromagnetic coupling strengthening treatment can generate a dense TiN layer on the surface of the cutting tool, greatly improve the surface hardness and wear resistance of the cutting tool, and at the same time, enhance the oxidation resistance, resist thermal fatigue and oxidation wear in high-temperature cutting; the multi-layer coating treatment can form a gradient-optimized structure by depositing CrAlN, CrAlSiN and CrAlBN coating layers layer by layer, which takes into account the hardness, wear resistance, toughness and high-temperature resistance, not only reduces the friction coefficient, but also significantly improves the bonding force between the coating and the substrate, avoiding the problem of coating peeling.

[0127] In the comparative example 1, the binder phase only contains metal cobalt powder without the addition of titanium-based alloy powder, which leads to a significant decrease in the high-temperature strength and heat resistance of the cutting tool, the binder phase is easy to soften and fail in high-temperature cutting, and the specific strength and lightweight characteristics of the titanium-based alloy are lacking, resulting in insufficient overall strength and rigidity of the tool, and the increase in weight affects the cutting efficiency;

[0128] In the comparative example 2, the additive does not contain modified CeO2, which leads to uneven microstructure of the cutting tool material, weakened interfacial bonding force, decreased sintering densification effect, and easy formation of stress concentration points in the material, thereby reducing the crack resistance; in high-temperature cutting, the binder phase softens intensively, causing the high-temperature strength and heat resistance of the material to decrease, and due to the lack of the antioxidant effect of CeO2, the cutting tool surface is easy to oxidize and corrode, significantly reducing the wear resistance and service life;

[0129] In the comparative example 3, there is no pressurized sintering stage in the sintering method, which leads to insufficient densification of the cutting tool material, easy residual of micro-pores in the interior, thereby reducing the mechanical strength and toughness of the material, and also weakening the interfacial bonding force, leading to uneven microstructure; in high-temperature cutting, the heat resistance and fatigue resistance of the material decrease, and cracks are easy to expand or break, thereby shortening the tool life;

[0130] In the comparative example 4, the cutting tool is not subjected to electromagnetic coupling strengthening treatment, and a dense TiN layer is not formed on the surface of the cutting tool, resulting in insufficient surface hardness and wear resistance, and reduced oxidation resistance, which is easy to be affected by oxidation and thermal fatigue in high-temperature cutting, and the surface wear is intensified;

[0131] In the comparative example 5, the cutting tool is not subjected to surface coating treatment, and the cutting tool surface lacks the protection of the multi-layer coating, leading to a significant decrease in wear resistance and high-temperature resistance, and in the cutting process, the tool surface directly contacts the workpiece, the friction coefficient increases, and serious wear and built-up edge are easy to occur, and the lack of coating also leads to weakened oxidation resistance, and the tool surface is easy to be oxidized and corroded in a high-temperature environment, and the service life is greatly shortened.

[0132] The above examples are only used to illustrate the technical solutions of the present application, and are not limiting; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can modify the technical solutions described in the foregoing examples, or make equivalent substitutions for part of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of machining a titanium alloy material with a cutting tool, characterized by, The method comprises the following steps: S1, ingredients are prepared according to the following weight percentage: Hard phase WC 75%-80%; Binder phase 10%-15% composed of metal cobalt and titanium-based alloy powder, wherein the metal cobalt accounts for 50%-60% of the total amount of the binder phase, the titanium-based alloy powder accounts for 40%-50%, and the chemical composition of the titanium-based alloy powder is: titanium 68%-75%, aluminum 15%-25%, vanadium 4%-8%; Additives 5%-8% composed of the following ingredients: TiO2 2%-3%, TiB2 1%-2%, and modified CeO2 2%-3%; The modification process of the modified CeO2 is as follows: CeO2 particles with a particle size of 100-200 nm are placed in an ultrasonic cleaning device, a mixed solution of deionized water and anhydrous ethanol with a volume ratio of 1:1 is added, and cleaning is performed for 10-15 min, followed by filtration with filter paper, and the CeO2 particles are taken out. Then the CeO2 particles are placed in an oven at 60-80℃ and dried for 3-5h to ensure that there is no residual liquid on the surface of the CeO2 particles. Then the CeO2 particles are placed in a vacuum plasma treatment device, the cavity of the vacuum plasma treatment device is vacuumized to a vacuum degree below 0.001 Pa, high-purity Ar is introduced into the cavity, the pressure in the cavity is maintained at 20-50 Pa, the radio frequency plasma source is started, the frequency is 13.56 MHz, the power is 200-400 W, and the CeO2 particles are uniformly bombarded in the plasma environment for 3-5 min; S2, the hard phase, the binder phase and the additives are put into a ball mill for ball milling, and a mixed powder is obtained after spray drying; S3, the mixed powder is pressed into a tool blank; S4, the tool blank is sintered by a segmented sintering method; S5, the sintered tool blank is mechanically cut to obtain a cutting tool; S6, the cutting tool is subjected to electromagnetic coupling strengthening treatment and surface coating treatment in sequence to form TiN layer, CrAlN layer, CrAlSiN layer and CrAlBN layer on the surface of the cutting tool in sequence; The specific process of electromagnetic coupling strengthening treatment is as follows: after ultrasonic cleaning of the cutting tool, the cutting tool is loaded into an electromagnetic coupling treatment device, the electromagnetic field frequency is set to 2 MHz, the magnetic field strength is 150 mT, then high-purity nitrogen gas is introduced, the gas flow is controlled at 60-80 L / min, then the temperature is gradually increased to 600-800℃ at a rate of 10-15℃ / min, so that the nitrogen gas is decomposed into high-energy active nitrogen ions, and a TiN layer is formed on the surface of the cutting tool; The specific process of surface coating treatment is as follows: Under Ar atmosphere, the cutting tool is subjected to ion bombardment treatment with a substrate bias of-180 V, the bombardment time is 10-20 min, then high-purity N2 is introduced, the flow is controlled at 40-50 sccm, a substrate bias of-170 V is applied, the Cr and Al targets are started, the sputtering power is 140 W and 130 W respectively, and the deposition time is 60 min to obtain a CrAlN layer. The high-purity N2 was introduced on the basis of Ar, the flow rates of Ar and N2 were 40 sccm and 10 sccm respectively, and the target material was adjusted to Cr 0.35 Al 0.45 Si 0.10 alloy target material, the sputtering power was 150 W, the substrate bias was -100 V, and the deposition time was 30 min to obtain a CrAlSiN layer. Then high purity B2H6 was introduced in Ar and N2 atmosphere, the gas flow was 10-20sccm, and the target material was Cr 0.30 Al 0.60 B 0.10 , the sputtering power was 150W, the substrate bias was -100V, and the deposition time was 30min to obtain a CrAlBN layer.

2. The machining method for titanium alloy materials using cutting tools according to claim 1, characterized in that, The thickness of the TiN layer is 1-4 μm.

3. The machining method for titanium alloy materials using cutting tools according to claim 2, characterized in that, The thickness of the CrAlN layer is 0.5-0.7 μm, the thickness of the CrAlSiN layer is 0.6-0.8 μm, and the thickness of the CrAlBN layer is 0.7-0.9 μm.

4. The method of claim 1, wherein, In step S2, ethanol is added as a ball milling medium during ball milling of the raw material, and 0.5wt% polyethylene glycol is added as a forming agent for ball milling, the ball powder ratio is 10:1, and the ball milling time is 12-24 h.

5. The method of claim 1, wherein, In step S3, the mixed powder is first subjected to preliminary pressing by a cold isostatic pressing device, the pressing pressure is 200-300 MPa, and then the preliminary pressed tool blank is placed into a hot isostatic pressing device for high-temperature compaction treatment, the temperature is controlled at 900-1100℃, the pressure is 50-100 MPa, and the holding time is 1-2 h.

6. The method of claim 1, wherein, In step S4, the method of segmented sintering is specifically as follows: S41, dewaxing stage: after vacuumizing the sintering furnace to 20-50 Pa, hydrogen is introduced, the furnace temperature is raised to 350-400℃ at a heating rate of 35-45℃ / min, and the temperature is maintained for 4-6 h; S42, vacuum sintering stage: the furnace temperature is raised to 1250℃ at a heating rate of 20-25℃ / min, and the temperature is maintained for 50-60 min, then the furnace temperature is raised to 1350℃ at a heating rate of 8-10℃ / min, and the temperature is maintained for 70-90 min; S43, pressure sintering stage: after vacuum sintering is completed, argon is introduced into the furnace, the pressure in the furnace is raised to 50-100 mbar, and the furnace temperature is raised to 1450-1500℃ at a heating rate of 5℃ / min, and maintained for 30-60 min; S44, cooling stage: after stopping heating, the furnace temperature is lowered to 1000℃ at a cooling rate of 12-25℃ / min, 950-980 mbar of argon is introduced for forced cooling at this temperature, and the cooling rate is controlled at 10-15℃ / min until the furnace temperature is lower than 100℃, and the tool blank is taken out.

7. A cutting tool of a titanium alloy material, characterized by, The cutting tool is prepared by the cutting tool machining method of the titanium alloy material according to any one of claims 1-6. The cutting tool is prepared by the cutting tool machining method of the titanium alloy material according to any one of claims 1-6.

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