CN115786875A - Coating with enhanced toughness and wear resistance and preparation method and application thereof - Google Patents
Coating with enhanced toughness and wear resistance and preparation method and application thereof Download PDFInfo
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Abstract
The invention relates to a coating with enhanced toughness and wear resistance, a preparation method and application thereof, comprising a Co-containing hard matrix and a hard coating coated on the matrix; the hard coating comprises a layer of ultra-fine, nanocrystalline Ti (C) with a thickness >1 μm prepared by a chemical vapour deposition process x N y O z ) The coating is characterized in that x + y + z =1, x is more than or equal to 0.5 and less than or equal to 0.7, y is more than or equal to 0.3 and less than or equal to 0.5, and z is more than 0 and less than or equal to 0.2. The invention enables the substrate to be heated after the coating is depositedThe Co-containing bonding metal is orderly diffused and uniformly distributed at the grain boundary of the coating, so that the film-substrate binding force and the coating cohesion are improved. The invention can effectively improve the problems of the weakening of the grain boundary strength caused by the enrichment of chlorine impurities in the grain boundary of the coating and the reduction of the toughness of the coating caused by the doping and hardening of oxygen elements. The coating has high hardness, high toughness and grain boundary strength, and can greatly improve the anti-tipping and tipping capabilities, the wear resistance and the service life when being used as a metal processing cutting tool.
Description
Technical Field
The invention relates to a chemical vapor deposition coated cutting tool for metal machiningAnd a preparation method thereof, in particular to a Ti (C) -containing alloy with enhanced toughness and wear resistance x N y O z ) A chemical vapor deposition coating cutting tool, a preparation method and application thereof belong to the category of hard materials and hard coating cutting tools.
Technical Field
The surface of a hard material matrix comprising hard alloy and metal ceramic is coated, so that the wear resistance, corrosion resistance, chemical stability and high temperature resistance of the hard material cutting tool can be greatly improved. The coating methods commonly used in the industry mainly include Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD). Commercial CVD coated cemented carbide tool surface coatings typically have TiN/TiCN/TiAlOCN/alpha-Al 2 O 3 the/TiN composite structure, wherein the TiCN coating is generally prepared by adopting a medium-temperature chemical vapor deposition method (MT-TiCN for short).
Compared with a high-temperature chemical vapor deposition TiCN (HT-TiCN for short) coating, the MT-TiCN coating has lower deposition temperature, can inhibit the generation of a decarbonization phase at the interface of the coating and a substrate, is favorable for reducing the damage of the CVD coating to the toughness of the substrate, and is widely applied to the industrial production of coated cutters.
The MT-TiCN coating is one of important functional layers and has good anti-flank wear performance. However, MT-TiCN coatings are generally coarse columnar crystals and not very hard. But the wear resistance can be further improved by doping alloying elements to reduce the grain size or increase the carbon content to increase the hardness. The hardness of the material is improved along with the reduction of the grain size of the alloy, and the improvement of the hardness of the material is beneficial to the improvement of the wear resistance of the material.
Patent CN100549222C provides a method for regulating and controlling the grain size and microstructure of MT-TiCN coating. The invention adopts CO and CO 2 、ZrCl 4 Or AlCl 3 Doping to obtain a fine equiaxed grain structure MT-TiCN coating at the level of nanocrystals. The MT-TiCN coating has higher wear resistance and is particularly suitable for cutting plastic metals such as stainless steel.
Patent CN101688311A discloses a chromium, vanadium or silicon doped TiCN coating. The invention is controlled by introducing in the TiCN deposition processPreparation of CrCl 2 、VCl 3 Or SiCl 4 The partial pressure of the oxygen-containing gas is used for regulating and controlling the content of the doping elements in the coating. The coated tool of the invention has improved wear resistance and higher cutting life in cutting machining of steel, cast iron and stainless steel.
Patent CN103506640B discloses a TiBCN coated cutting tool prepared by a CVD method and having a boron content of 0.5at% to 10at% and a preparation method thereof. The invention patent adds BCl in the deposition process of MT-TiCN coating 3 And the gas enables boron to be doped into the MT-TiCN coating, so that the hardness and the wear resistance of the coating are obviously improved, and the cutting performance of the coated cutter is more excellent.
Patent CN104099580A discloses a nanocrystalline tool coating with enhanced wear resistance and toughness. The method regulates and controls CH of reaction gas in chemical vapor deposition 4 、C 2 H 6 、C 2 H 4 、C 2 H 2 、N 2 And CH 3 CN is combined and proportioned to prepare the nano columnar crystal MT-TiCN with the grain size of 50-150 nm. The coating can obviously improve the wear resistance and the shock resistance of the cutting tool, and has excellent performance in the cutting of materials such as steel, cast iron, stainless steel and the like.
The paper "Atom probe catalysis on polycrystalline Ti (C, N) and Zr (C, N) CVD coatings" (Azhari et al script materials, 162 (2019) 335-340) reports the grain boundary composition of a polycrystalline TiCN coating deposited by medium temperature chemical vapor deposition on a WC-Co cemented carbide substrate. The atomic probe analysis result shows that the impurity Cl element aggregation existing at the grain boundary is an intrinsic defect of the MT-CVDTiCN coating, and the defect can cause the weakening of the grain boundary strength.
The following conclusions can be drawn by comparing the prior art: the grain size of the MT-TiCN coating can be obviously reduced by reasonably regulating and controlling the components of the CVD mixed gas, so that the hardness and the wear resistance of the coating are obviously improved. However, the improvement of the hardness of the coating easily causes the reduction of the toughness of the coating, and the chipping or micro-chipping is easily generated in the cutting process, so that the coated cutting tool is prematurely failed, and the prior invention cannot solve the series problems of the weakening of the grain boundary strength, the reduction of the coating cohesion, the increase of the coating brittleness and the like caused by the segregation of the element Cl in the grain boundary impurity of the MT-TiCN coating.
Disclosure of Invention
In view of the defects of the prior art, the invention mainly aims to solve the problems that the grain boundary bonding strength of the MT-TiCCNCVD coating is not high and the toughness of the coating is reduced after the oxygen-doped hardness of the coating is improved.
The invention relates to a coating with enhanced toughness and wear resistance, which is a hard coating coated on a substrate, wherein the substrate is a Co-containing hard substrate; the hard coating comprises a layer of Ti (C) deposited by CVD to a thickness of >1 μm x N y O z ) The coating is characterized in that x + y + z =1, x is more than or equal to 0.5 and less than or equal to 0.7, y is more than or equal to 0.3 and less than or equal to 0.5, z is more than 0 and less than or equal to 0.2, and the concentration of the grain boundary of the coating is distributed>1.0at.% of a matrix bonding metal; the hard coating has high toughness and wear resistance, and the surface roughness Ra of the hard coating is less than 0.7 mu m; the Co-containing hard matrix refers to Co-containing hard alloy and Co-containing metal ceramic; the matrix bonding metal refers to Co or Co and Ni in a Co-containing hard matrix; the CVD refers to chemical vapor deposition; the at.% refers to atomic percentage; the Co-containing hard alloy refers to that the bonding metal of the hard alloy contains Co, and the hard alloy used as a coating substrate usually adopts single metal Co as the bonding metal; the Co-containing cermet refers to cermet containing Co in the binding metal, and the cermet usually adopts Co and Ni as the binding metal.
The invention relates to a coating with enhanced toughness and wear resistance, which is characterized in that after the coating is deposited, bonding metal in a matrix is diffused to a coating grain boundary by adopting heat treatment; the post-deposition heat treatment of the coating can be continued in a CVD coating furnace in pure H after the coating deposition 2 The coating deposition can be carried out in the atmosphere, or can be carried out in the vacuum or inert atmosphere after the coating is deposited out of the furnace; the heat treatment temperature after the deposition of the coating is lower than the appearance temperature of a liquid phase in the Co-containing hard matrix and is 1000-1100 ℃, and the heat treatment heat preservation time is 200-400 min; the appearance temperature of liquid phase in the alloy system is higher than 1100 ℃ and usually higher than 1280 ℃ in both Co-containing hard alloy and Co-containing cermet.
The coating with enhanced toughness and wear resistance has the total thickness of 5-30 mu m; the coating is formed by sequentially and outwardly distributing 5 layers from a matrix, wherein the 1 st layer is TiN or TiC or TiCN, preferably TiN, and the thickness of the coating is 0.1-2 mu m; the 2 nd layer is Ti (C) x N y O z ) The thickness is 2 to 15 mu m; the 3 rd layer is TiAlOCN with the thickness of 0.1-1 μm; the 4 th layer is alpha-Al 2 O 3 The thickness is 2 to 15 mu m; the 5 th layer is a top TiN coloring layer with the thickness of 0.1-2 mu m.
The invention relates to a coating with enhanced toughness and wear resistance, and the 2 nd layer Ti (C) x N y O z ) The coating is superfine and nanocrystalline, and the average grain size of the coating is less than 0.2 mu m.
The invention relates to a preparation method of a coating with enhanced toughness and wear resistance, which is a hard coating coated on a substrate; the substrate is a Co-containing hard substrate; the hard coating comprises a layer of Ti (C) deposited by CVD to a thickness of >1 μm x N y O z ) A coating, wherein x + y + z =1, 0.5. Ltoreq. X.ltoreq.0.7, 0.3. Ltoreq. Y.ltoreq.0.5, 0. Ltoreq. Z.ltoreq.0.2, characterized in that the concentration is distributed at the grain boundaries of the coating>1.0at.% of a matrix bonding metal; the Co-containing hard matrix refers to Co-containing hard alloy and Co-containing metal ceramic; the matrix bonding metal refers to Co or Co and Ni in a Co-containing hard matrix; the CVD refers to chemical vapor deposition; after the coating is deposited, adopting heat treatment to diffuse the bonding metal in the matrix to the coating grain boundary; the post-deposition heat treatment of the coating can be continued in a CVD coating furnace in pure H after the coating deposition 2 The coating can be carried out in the atmosphere, or can be carried out in the vacuum or inert atmosphere after the coating is deposited out of the furnace; the heat treatment temperature after the deposition of the coating is lower than the appearance temperature of a liquid phase in the Co-containing hard matrix and is 1000-1100 ℃, and the heat treatment heat preservation time is 200-400 min; the total thickness of the coating is 5-30 mu m; 5 layers of TiN, tiC or TiCN, preferably TiN are sequentially distributed outwards from the substrate on the coating, and the thickness of the coating is 0.1-2 mu m; the 2 nd layer is Ti (C) x N y O z ) The thickness is 2-15 μm; the 3 rd layer is TiAlOCN with a thickness of 0.1 to1 μm; the 4 th layer is alpha-Al 2 O 3 The thickness is 2-15 μm; the 5 th layer is a top TiN coloring layer with the thickness of 0.1-2 mu m; the 2 nd layer of Ti (C) x N y O z ) The coating is superfine and nanocrystalline, and the average grain size of the coating is less than 0.2 mu m; the coating is subjected to mechanical treatment on the surface of the coating before leaving a factory; the mechanical treatment of the surface of the coating refers to that the surface of the coating is treated by wet sand blasting and polishing in sequence, so that the surface roughness Ra of the coating is less than 0.7 mu m.
The invention relates to a preparation method of a coating with enhanced toughness and wear resistance, which comprises the following steps: under the conditions of 900-1000 deg.C and 100-400 mbar, tiCl is added 4 、N 2 And H 2 Is used as a precursor and is prepared by chemical reaction. In industrial application, if the 1 st layer and the 5 th layer are both TiN layers; then all can be prepared using the above TiN layer preparation method. When the layer 1 coating is made of other materials, the coating can be prepared by the existing method.
The invention relates to a preparation method of a coating with enhanced toughness and wear resistance, and Ti (C) x N y O z ) Coating, i.e. 2 nd layer, with TiCl 4 、N 2 、CO、H 2 And CH 3 CN mixed gas is used as a precursor, and is prepared by chemical reaction at the temperature of 800-900 ℃ and under the condition of 50-200 mbar; the Ti (C) x N y O z ) The content of O in the coating is controlled by the volume fraction of CO in the mixed gas; the Ti (C) x N y O z ) The superfine and nano-crystallization of the grain size of the coating is realized by increasing the volume fraction of CO in the mixed gas; the volume fraction of the CO in the mixed gas is more than 2% but less than 8%; the volume fraction of CO in the mixed gas is increased by reducing the volume fraction of carrier gas H in the mixed gas 2 Is achieved by volume fraction (v).
The invention relates to a preparation method of a coating with enhanced toughness and wear resistance, wherein the TiAlOCN coating is made of TiCl 4 、N 2 、H 2 、CH 4 、CO、CO 2 And AlCl 3 The mixed gas is a precursor and is prepared by chemical reaction at 900-1000 ℃ and 50-200 mbar.
The invention relates to a preparation method of a coating with enhanced toughness and wear resistance, and Al 2 O 3 Coating with H 2 、AlCl 3 And CO 2 The mixed gas is used as a precursor and H 2 S is a catalyst and is prepared by chemical reaction at 900-1000 ℃ and 100-250 mbar.
The thickness of each layer in the coating can be regulated and controlled by the deposition time of the coating.
The invention relates to an application of a coating with enhanced toughness and wear resistance, which is used as a cutting tool for metal processing; the coated blade used as a metal processing cutting tool is subjected to mechanical treatment on the surface of a coating before leaving a factory; the mechanical treatment of the surface of the coating refers to that the surface of the coating is treated by wet sand blasting and polishing in sequence, so that the surface roughness Ra of the coating is less than 0.7 mu m.
The mechanism and advantages of the invention are briefly described as follows:
by regulating and controlling the volume fraction of CO (carbon monoxide) in the mixed gas, superfine nanocrystalline Ti (C) is obtained x N y O z ) Thereby improving the hardness and wear resistance of the coating. The invention discovers, through system experiment research, that the volume fraction of CO in the mixed gas is controlled to be more than 2 percent but less than 8 percent, and the mixed gas is ultrafine nanocrystalline Ti (C) x N y O z ) The comprehensive performance of the coating is optimal; within this range, increasing the CO concentration results in Ti (C) x N y O z ) The grain size of the coating is effectively reduced, and nanocrystallization is realized.
By reacting in pure H 2 In an atmosphere or inert atmosphere or in vacuum, with the aid of Ti (C) at a temperature below the temperature at which the liquid phase of the Co-containing hard matrix occurs x N y O z ) The superfine nano-crystalline property (average grain size less than 0.2 mu m) and the enhanced driving effect on the migration of Co or Co, ni and other bonding metals in a Co-containing hard matrix and the regulation and control effect on the migration paths of Co, ni and other bonding metals enable solid bonding metal atoms in the matrix to slowly and orderly migrate and diffuse along the growth direction of the coating and to be uniformly distributed at the grain boundary of each layer of coating in the form of a film with atomic-level thickness, thereby realizing the inter-grain boundary of the coatingImproved bond strength, improved toughness of the coating, and improved resistance to cohesive failure of the coating. The improvement of the bonding strength of the coating grain boundary can improve the cohesion and the film-substrate bonding force of the coating and reduce the brittleness of the coating, thereby improving the anti-tipping and anti-tipping capabilities of the coated cutter. However, the heat treatment temperature is too high or the heat preservation time is too long after the coating is deposited, so that the migration and diffusion of the bonding metal are out of control easily, and the coating defect is formed. The invention discovers through system experiment research that the coating cutter can obtain the best comprehensive performance when the heat treatment temperature is 1000-1100 ℃ and the heat preservation time is 200-400 min after the coating is deposited; under the process conditions, the migration amount and distribution state of the bonding metal in the matrix migrating to the coating can reach the optimal conditions required for optimizing the comprehensive performance of the coated cutter.
In conclusion, the invention can effectively improve the TiCl passing through 4 、AlCl 3 The coating prepared by the chemical vapor deposition in-situ reaction with the participation of chlorides comprises an MT-Ti (C, N, O) coating, and the problems of the reduction of the grain boundary strength, the interlayer bonding strength, the coating cohesion and the coating toughness caused by the enrichment of chlorine impurities at the grain boundary and the reduction of the coating toughness caused by the increase of the coating hardness after the doping of oxygen elements, so that the coating toughness, the coating cohesion failure resistance and the film-substrate bonding force can be effectively improved, the edge breakage (micro-edge breakage) and the edge breakage in the service process of the coating cutter are reduced, the coating abrasion resistance is improved, and the service life and the service performance stability of the coating cutter are improved.
The present invention is further described in detail with reference to the drawings and examples, but the coating with enhanced toughness and wear resistance of the present invention, and the preparation method and application thereof are not limited to the examples. The method for evaluating the toughness and the wear resistance of the coated blade adopts the general tipping resistance (performance) and cutting life in the field of cutting tools to carry out comprehensive evaluation.
Drawings
FIG. 1 is a scanning electron micrograph (a) of a micro-region in which MT-Ti (C, N, O) is present in a coating section of a comparative sample B which is not subjected to heat treatment of the coating and a result (B) of energy spectrum analysis of a square frame identification region in the figure;
FIG. 2 is a scanning electron micrograph (a) of a micro-region where MT-Ti (C, N, O) is located in a coating section of sample A subjected to heat treatment of the coating and a result (b) of energy spectrum analysis of a box-labeled region in the figure.
As can be seen from fig. 1 and 2, trace impurity Cl element was present in the MT — Ti (C, N, O) layer of the comparative sample B which was not subjected to the coating heat treatment, but Co element was not detected; the grain boundaries of the MT — Ti (C, N, O) layer of the coating heat-treated sample a were white linear due to the presence of Co element diffused from the matrix into the coating, and the results of the energy spectrum analysis also showed that the coating contained Co element in an atomic fraction of 1.39%.
Detailed Description
The present invention will be further described with reference to examples, comparative examples and the accompanying drawings.
Example one
A cemented carbide indexable insert (CNMG 120408E, turning tool) was coated with 5 coats using CVD technique, the cemented carbide composition comprising: 7% of Co (mass fraction, the same applies hereinafter), 3.5% of cubic carbide, and the balance WC. The five layers have a thickness of about 16.5 μm and are made of TiN (about 0.5 μm), MT-TiCNO (about 8 μm), tiAlOCN (about 0.5 μm), α -Al 2 O 3 (about 7 μm) and TiN (about 0.5 μm). The three samples are referred to as sample a, sample B (control 1), and sample C (control 2), respectively. The three sample coating processes were identical as described in table 1.
TABLE 1 Process parameters for coating deposition
Except that sample a was continued in a CVD coating furnace in pure H after coating deposition 2 Carrying out heat treatment (in-situ heat treatment after coating) at 1100 ℃ for 200min in the atmosphere; after the coating was deposited, sample B was directly subjected to the cooling stage without heat treatment. And (3) depositing and cooling the coating of the sample C, and then carrying out heat treatment at 1130 ℃ for 500min in a vacuum furnace. FIG. 1 is a scanning electron micrograph of a micro-region in which an MT-Ti (C, N, O) coating layer is present in the coating layer of sample B (which is not subjected to a post-coating-deposition heat treatment) and the results of energy spectrum analysis of the box-labeled region in the figure. As can be seen from FIG. 1Trace amounts of impurity element Cl were present in the MT-Ti (C, N, O) coating, but no element Co was detected. FIG. 2 is a scanning electron micrograph of a coating layer of sample A (subjected to a post-coating-deposition heat treatment) in which MT-Ti (C, N, O) is present in a micro-region and the result of energy spectrum analysis of a box-labeled region in the figure. As can be seen from the electron back scattering image of the scanning electron microscope shown in fig. 2, the grain boundary of the coating appears white linear due to the Co element diffused from the matrix to the coating, and the energy spectrum analysis result shows that the coating contains Co with an atomic fraction of 1.39%. Based on the X-ray diffraction analysis results of the polished sections of the coatings of the samples A and B, the results calculated by using a Scherrer formula show that the average grain size of the prepared MT-Ti (C, N, O) coating is 50nm. From the energy spectrum analysis result of FIG. 1B, the atomic fractions of C, N and O in MT-Ti (C, N and O) on the surface of sample B are 0.55, 0.33 and 0.12, respectively. From the energy spectrum analysis result of fig. 2b, the atomic fractions of C, N, and O in MT-Ti (C, N, O) on the surface of sample a are 0.52, 0.35, and 0.13, respectively.
The cutting comparison experiment is carried out on the samples A, B and C in the first embodiment by turning the steel piece, and the test quantity of the three groups of blade samples is 5. The surface of the coating was treated with wet blasting and polishing, respectively, before the cutting test, and the surface roughness Ra =0.15 μm was measured. The cutting experiment parameters were as follows:
the operation is as follows: continuous turning
Workpiece shape: a cylindrical member;
materials: 45 # Carbon steel;
blade type: CNMG 120408E;
cutting speed: 300m/min;
feeding amount: 0.3mm/rev;
cutting deeply: 2.0mm;
cutting mode: wet cutting
Turning experiment results show that when the cutting time of one sample in the comparative sample B reaches 14 minutes, the phenomenon of coated cutter failure caused by micro-chipping or edge chipping appears in the rest four samples after the cutting is finished for 18 minutes. In comparative sample C, after 9 minutes of cutting, the coated cutting tool failure due to micro-chipping or edge chipping is observed. The results of measurement of the three kinds of blade flank wear amounts VB (in mm) are shown in table 2, where the blade flank wear amount VB after cutting for comparative sample B for 14 minutes is an average measurement of 4 samples.
TABLE 2 flank wear, mm of turning insert
| Sample numbering | 4 minutes | 9 minutes | 14 minutes | 18 minutes |
| Sample A | 0.04 | 0.07 | 0.12 | 0.30 |
| Sample B (control 1) | 0.05 | 0.12 | 0.29 | Fail to work |
| Sample C (control 2) | 0.09 | Fail of |
As can be seen from table 2, the present invention significantly improves the wear resistance as well as the chipping and mouth resistance of the coated tool. Obviously, the improvement of the wear resistance of the coated cutter is closely related to the hardness increase accompanied by the nano effect of the microstructure of the MT-Ti (C, N, O) coating; the improvement of the chipping resistance and the anti-oral cavity breaking capability is closely related to the improvement of the toughness of the coating. Notably, excessive heat treatment can lead to premature failure of the tool.
In order to more authoritatively and professionally characterize the toughness of the coated inserts, the impact toughness tests of samples a and B of example one were carried out according to the general method of evaluating the impact toughness of cutting inserts in the field of cutting tools. The experimental method is to turn round bar with 4 symmetrical grooves on the end face. When the blade is broken or damaged, the blade is considered to be failed, and the impact toughness of the blade, namely the number of times of impacts which can be borne by the blade is evaluated by the number of the blade which cuts through the groove. Sample C was not tested for impact toughness because it was significantly less resistant to chipping than sample a and sample B.
The cutting experiment parameters were as follows:
the operation is as follows: interrupted turning
Shape of the workpiece: cylindrical part with groove
Materials: 45 # Carbon steel
The type of blade: CNMG120408E
Cutting speed: 270m/min
Feeding amount: 0.18mm/rev
Cutting depth: 1.5mm
Cutting mode: dry cutting
TABLE 3 number of impacts sustained by the turning insert
| Sample numbering | First group | Second group | Third group | Fourth group |
| Sample A | 4090 | 4856 | 4538 | 4672 |
| Sample B (comparison sample) | 3568 | 2627 | 3153 | 3866 |
As can be seen from table 3, even if the sample a subjected to the post-deposition heat treatment of the coating is subjected to repeated mechanical impact and thermal impact during cutting, the coating is not easily damaged and peeled off, and the chipping resistance of the cutting tool are significantly improved. Clearly, improvements in chipping resistance and resistance to chipping correlate well with improvements in coating toughness.
Example two
A TiCN-based cermet indexable insert (CNMG 120408E, turning tool) was coated with 5 coats using CVD technique. The TiCN-based cermet comprises the following components: 7.5% of Co (mass fraction, the same applies hereinafter), 7.5% of Ni,20% by weight of WC,5% of Mo 2 C. 3% TaC, 3% NbC and the balance TiC 0.5 N 0.5 . The 5-layer coating has a total thickness of about 13.5 μm and is made of TiN (about 0.5 μm), MT-Ti (C, N, O) (about 8 μm), tiAlOCN (about 0.5 μm), alpha-Al 2 O 3 (about 4 μm) and TiN (about 0.5 μm). Two kinds of sample quiltReferred to as sample D and sample E (control), respectively. The two sample coating processes were identical. The reaction gas composition, deposition pressure and temperature were as described in table 1, and only the deposition time of the coating was adjusted to achieve the purpose of changing the thickness of the coating. After the coating is deposited and discharged from the furnace, carrying out heat treatment on the sample D in a vacuum furnace at 1050 ℃ for 240 min; sample E was not heat treated after coating deposition. Analysis of the composition of the coating microdomains after heat treatment according to the measurement method described in example one showed that sample D had an average atomic percentage of Co and Ni in the coating of 0.71% and 0.64%, respectively, and a total average atomic percentage of Co and Ni in the coating of 1.35%.
The comparative cutting tests were carried out on samples D and E of example two by turning cast iron, and the number of samples tested was 5 for both sets of inserts. Before the cutting experiment, the surface of the coating is treated by wet blasting and polishing, and the surface roughness Ra =0.15 μm is measured. The cutting experiment parameters were as follows:
the operation is as follows: continuous turning
Workpiece shape: cylindrical part
Materials: grey cast iron
Blade type: CNMG120408E
Cutting speed: 350m/min
Feeding amount: 0.3mm/rev
Cutting deeply: 1.8mm
Cutting mode: dry cutting
Turning experiment results show that when the cutting time of 4 samples in the comparative sample E reaches 24 minutes, the flank face abrasion loss is observed to be larger than 0.3mm, and the samples are judged to be invalid, wherein 1 sample has a coating cutter invalidation phenomenon caused by edge breakage after cutting for 24 minutes. The results of measurement of two kinds of blade flank wear amounts VB (in mm) are shown in table 4, where the blade flank wear amount VB after 18 minutes of cutting of the control sample E is an average measurement of 4 samples because one of the samples has developed a micro chipping. The failure form of control E after cutting time of up to 24 minutes was that flank wear had been greater than 0.3mm and chipping. The failure criterion for flank wear to reach 0.3mm is a standard commonly used in the industry.
TABLE 4 flank wear, mm, of turning inserts
| Sample numbering | 6 minutes | 12 minutes | 18 minutes | 24 minutes | 32 minutes |
| Sample D | 0.08 | 0.14 | 0.20 | 0.25 | 0.30 |
| Sample E (comparison sample) | 0.12 | 0.19 | 0.28 | Fail to work |
As can be seen from table 4, the present invention significantly improves the wear resistance of the coated tool.
EXAMPLE III
Cemented carbide indexable by CVD technologyThe insert (SNGX 1206ANN, milling cutter) was coated with 5 layers of coating, the cemented carbide composition comprising: 10% of Co (mass fraction, the same applies hereinafter), 1.5% of (Ti, ta, nb) C and the balance of WC. The 5-layer coating has a total thickness of about 6.5 μm and is made of TiN (about 0.5 μm), MT-Ti (C, N, O) (about 2.2 μm), tiAlOCN (about 0.5 μm), alpha-Al 2 O 3 (about 3.0 μm) and TiN (about 0.3 μm). The two samples are referred to as sample F, sample G (control 1), respectively. The two sample coating processes were identical. The reaction gas composition, deposition pressure and temperature were as described in table 1, and only the deposition time of the coating was adjusted to achieve the purpose of changing the thickness of the coating. After the coating is deposited and discharged from the furnace, the sample F is subjected to heat treatment at 1000 ℃ for 400min in a high-purity Ar gas in a tubular furnace; sample G was not heat treated after the coating was deposited.
The cutting comparison experiment was performed on sample F and sample G of example three by milling the steel piece, and the test number of the two sets of blade samples was 5 pieces each. Before the cutting experiment, the surface of the coating is treated by wet blasting and polishing, and the surface roughness Ra =0.15 μm is measured. The cutting experiment parameters were as follows:
the operation is as follows: face milling
Workpiece shape: square piece
Materials: alloy steel
The type of blade: SNGX1206ANN
Milling speed: 200m/min
Milling feed amount: 0.2mm/z
Milling and cutting depth: 1mm
Milling width: 60mm
Cutting mode: dry cutting
The results of the blade flank wear VB (in mm) are shown in Table 5. The samples G all showed varying degrees of coated tool failure due to chipping or edge chipping after cutting times of more than 16 minutes.
TABLE 5 flank wear, mm, of milling inserts
| Sample numbering | 4 |
10 minutes | 16 minutes | 22 minutes |
| Sample F | 0.04 | 0.14 | 0.20 | 0.29 |
| Sample G (control 1) | 0.06 | 0.18 | 0.28 | Fail to work |
As can be seen from table 5 above, the coated cutting insert of the present invention has improved chipping and wear resistance of the tool.
Compared with the prior art, the cutting tool has the advantage that the service life of the cutting tool is obviously prolonged no matter turning or milling is carried out on the cutting tool.
The above examples are only intended to further illustrate the coating with enhanced toughness and wear resistance of the present invention, and the preparation method and application thereof, but the present invention is not limited to the examples, and any simple modifications, equivalent changes and modifications made to the above examples according to the technical spirit of the present invention fall within the scope of the technical solution of the present invention.
Claims (10)
1. A coating having enhanced toughness and wear resistance characterized by: the coating with enhanced toughness and wear resistance is a hard coating coated on a substrate, and the substrate is a Co-containing hard substrate; the hard coating comprises a layer of Ti (C) deposited by CVD to a thickness of >1 μm x N y O z ) The coating, wherein x + y + z =1, x is more than or equal to 0.5 and less than or equal to 0.7, y is more than or equal to 0.3 and less than or equal to 0.5, and z is more than 0 and less than or equal to 0.2; the grain boundary distribution concentration of the hard coating>1.0at.% of a base-bound metal, surface roughness Ra < 0.7 μm; the Co-containing hard matrix refers to Co-containing hard alloy and Co-containing metal ceramic; the matrix bonding metal refers to Co or Co and Ni in a Co-containing hard matrix; the CVD refers to chemical vapor deposition; the at.% refers to atomic percentage.
2. A coating having enhanced toughness and wear resistance as claimed in claim 1, wherein: after the coating is deposited, adopting heat treatment to diffuse the bonding metal in the matrix to the coating grain boundary; the post-deposition heat treatment of the coating can be continued in a CVD coating furnace in pure H after the coating is deposited 2 The coating deposition can be carried out in the atmosphere, or can be carried out in the vacuum or inert atmosphere after the coating is deposited out of the furnace; the heat treatment temperature after the deposition of the coating is lower than the appearance temperature of a liquid phase in the Co-containing hard matrix and is 1000-1100 ℃, and the heat treatment heat preservation time is 200-400 min.
3. A coating having enhanced toughness and wear resistance according to any one of claims 1 or 2, wherein: the total thickness of the coating is 5-30 mu m; the coating is formed by sequentially and outwardly distributing 5 layers from a matrix, wherein the 1 st layer is TiN or TiC or TiCN, preferably TiN, and the thickness of the coating is 0.1-2 mu m; the 2 nd layer is Ti (C) x N y O z ) The thickness is 2 to 15 mu m; the 3 rd layer is TiAlOCN with the thickness of 0.1-1 μm; the 4 th layer is alpha-Al 2 O 3 The thickness is 2-15 μm; the 5 th layer is a top TiN coloring layer with the thickness of 0.1-2 mu m.
4. An article of manufacture as claimed in any one of claims 1, 2 or 3 having enhanced toughness and resistanceAbrasive coatings characterized by: the Ti (C) x N y O z ) The coating is superfine and nanocrystalline, and the average grain size of the coating is less than 0.2 mu m.
5. A method for preparing a coating with enhanced toughness and wear resistance, characterized by: the coating with enhanced toughness and wear resistance refers to a hard coating coated on a substrate; the substrate is a Co-containing hard substrate; the hard coating comprises a layer of Ti (C) deposited by CVD to a thickness of >1 μm x N y O z ) The coating, wherein x + y + z =1, x is more than or equal to 0.5 and less than or equal to 0.7, y is more than or equal to 0.3 and less than or equal to 0.5, and z is more than 0 and less than or equal to 0.2;
the Co-containing hard matrix refers to Co-containing hard alloy and Co-containing metal ceramic; the matrix bonding metal refers to Co or Co and Ni in a Co-containing hard matrix; the CVD refers to chemical vapor deposition;
after the coating is deposited, the bonding metal in the matrix is diffused to the grain boundary of the coating by adopting heat treatment, and the matrix bonding metal with the concentration of more than 1.0at.% is distributed at the grain boundary of the coating;
the post-deposition heat treatment of the coating can be continued in a CVD coating furnace in pure H after the coating deposition 2 The coating deposition can be carried out in the atmosphere, or can be carried out in the vacuum or inert atmosphere after the coating is deposited out of the furnace; the heat treatment temperature after the deposition of the coating is lower than the appearance temperature of a liquid phase in the Co-containing hard matrix and is 1000-1100 ℃, and the heat treatment heat preservation time is 200-400 min;
the total thickness of the coating is 5-30 mu m; 5 layers of TiN, tiC or TiCN, preferably TiN are sequentially distributed outwards from the substrate on the coating, and the thickness of the coating is 0.1-2 mu m; the 2 nd layer is Ti (C) x N y O z ) The thickness is 2-15 μm; the 3 rd layer is TiAlOCN with the thickness of 0.1-1 μm; the 4 th layer is alpha-Al 2 O 3 The thickness is 2 to 15 mu m; the 5 th layer is a top TiN coloring layer with the thickness of 0.1-2 mu m; the 2 nd layer Ti (C) x N y O z ) The coating is superfine and nanocrystalline, and the average grain size of the coating is less than 0.2 mu m; the coating is subjected to mechanical treatment on the surface of the coating before leaving the factory; the mechanical treatment of the surface of the coating layer is that wet spraying is adopted successivelySanding and polishing the surface of the coating to a surface roughness Ra < 0.7 μm.
6. The method of claim 5, wherein the coating has increased toughness and wear resistance, and wherein: the preparation method of the TiN coating comprises the following steps: under the conditions of 900-1000 deg.C and 100-400 mbar, tiCl is added 4 、N 2 And H 2 Is used as a precursor and is prepared by chemical reaction.
7. The method of claim 5 for preparing a coating having enhanced toughness and wear resistance, wherein: the Ti (C) x N y O z ) Coating with TiCl 4 、N 2 、CO、H 2 And CH 3 CN mixed gas is used as a precursor, and is prepared by chemical reaction at the temperature of 800-900 ℃ and under the condition of 50-200 mbar; the Ti (C) x N y O z ) The content of O in the coating is controlled by the volume fraction of CO in the mixed gas; the Ti (C) x N y O z ) The superfine and nano-crystallization of the grain size of the coating is realized by increasing the volume fraction of CO in the mixed gas; the volume fraction of the CO in the mixed gas is more than 2% but less than 8%; the volume fraction of CO in the mixed gas is increased by reducing the carrier gas H in the mixed gas 2 Is achieved by volume fraction (v).
8. The method of claim 5 for preparing a coating having enhanced toughness and wear resistance, wherein: the TiAlOCN coating is made of TiCl 4 、N 2 、H 2 、CH 4 、CO、CO 2 And AlCl 3 The mixed gas is a precursor and is prepared by chemical reaction at 900-1000 ℃ and 50-200 mbar.
9. The method of claim 5, wherein the coating has increased toughness and wear resistance, and wherein: the Al is 2 O 3 Coating with H 2 、AlCl 3 And CO 2 The mixed gas is used as a precursor and H 2 S isThe catalyst is prepared by chemical reaction at 900-1000 ℃ and 100-250 mbar.
10. Use of a coating having enhanced toughness and wear resistance, characterized in that: the use of the coating with enhanced toughness and wear resistance is referred to as a metalworking cutting tool; the coated blade used as a metal processing cutting tool is subjected to mechanical treatment on the surface of a coating before leaving a factory; the mechanical treatment of the surface of the coating refers to that the surface of the coating is treated by wet sand blasting and polishing successively, so that the roughness Ra of the surface of the coating is less than 0.7 mu m.
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| CN202211469832.9A CN115786875A (en) | 2022-11-23 | 2022-11-23 | Coating with enhanced toughness and wear resistance and preparation method and application thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116162918A (en) * | 2023-04-26 | 2023-05-26 | 赣州澳克泰工具技术有限公司 | High-hardness high-toughness cutter coating and preparation method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116162918A (en) * | 2023-04-26 | 2023-05-26 | 赣州澳克泰工具技术有限公司 | High-hardness high-toughness cutter coating and preparation method thereof |
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