A high-strength, high-toughness and high-wear-resistant nickel-copper-based diamond composite material, its preparation method and application

Abstract

The present invention discloses a high-strength, high-toughness and high-wear-resistant nickel-copper-based diamond composite material, its preparation method and application. The composite material comprises 75-95 vol.% of nickel-copper alloy binder phase powder and 5-25 vol.% of diamond powder. The composite material is obtained by weighing the required nickel-copper alloy binder phase powder and diamond powder according to the configured ratio, mixing them by the acoustic resonance method, and then performing hot pressing sintering after pre-pressing deformation. The process flow is simple, the production cycle is short, the production cost is reduced, and it does not involve dangerous operations such as mechanical ball milling method, which is suitable for industrial production. The prepared composite material has high flexural strength, impact toughness and wear resistance at the same time. When used as the raw material of drill tools, working dies and grinding tools, it can significantly improve their wear resistance and extend the service life of each tool.

Description

Technical Field

[0001] The present invention relates to a metal matrix diamond composite material, in particular to a nickel-copper matrix diamond composite material and its preparation method and application, belonging to the field of composite material preparation. Background Art

[0002] Diamond composite materials are widely used in fields such as drilling tools, industrial dies, and grinding tools. Taking drilling tools as an example, compared with traditional welded drill bit bodies, the replaceable drill tooth crown bit is a new generation of drilling tool developed in recent years. It consists of polycrystalline diamond-carbide drill teeth and a steel crown body. However, due to the poor wear resistance and corrosion resistance of the steel crown body, the low service life of the crown body limits the further improvement of drilling efficiency and increases the processing cost. Compared with traditional steel materials, metal matrix diamond composite materials have significantly improved wear resistance. Preparing the crown body can effectively prevent its wear failure and extend its service life.

[0003] Currently, the diamond composite materials mainly use copper-based binder phases, but the wear resistance of copper-based alloys is low, which easily causes premature detachment of diamonds. Moreover, the high-temperature wetting angle between copper and diamond is about 150°. At high temperatures, the copper-based binder phase hardly wets diamond at all, and the prepared composite materials are prone to problems such as low bonding interface strength and low diamond holding force. Nickel-based alloys have excellent properties of wear resistance, high temperature resistance, and heat fatigue resistance, and the wetting angle between nickel and diamond is only 30°. If diamond composite materials with nickel-based alloys as binder phases can be developed, it is expected to obtain a metal binder-diamond interface with high bonding strength and prepare a new type of metal matrix-diamond composite material with high bending resistance, impact resistance, and wear resistance.

[0004] At present, there are relatively few patents and literatures on the preparation of nickel-based diamond composite materials under normal pressure. Among them, there are four Chinese patents with publication numbers CN115786772A, CN 115948679A, CN 115976368A, and CN 115971475A, as well as "Study on the Microstructure and Properties of Ni60 Coating with Added Diamond Particles" (Surface Technology, 2016: 45(9)), "Beneficial effects of laser irradiation on the deposition process of diamond / Ni60 composite coating with cold spray" (Applied Surface Science, 2015, 330: 300-308), and "Effects of diamond size on the deposition characteristic and tribological behavior of diamond / Ni60 composite coating prepared by supersonic laser deposition" (Diamond & Related Materials, 2015, 58: 139-148) reported the preparation of nickel-chromium alloy (Ni60)-diamond composite coatings, all of which belong to the field of surface modification technology. However, a large amount of brittle chromium carbide phase was generated at the interface between the matrix alloy and the diamond. 23 C6, etc.), the flexural strength of the composite material will be significantly reduced, which is not conducive to the long-term stable service of the composite material.

[0005] Chinese patents CN 112322938B and CN 112226638B both report additive manufacturing processes for nickel-based diamond composite materials. However, the methods for mixing the binder phase powder and the reinforcing phase powder in these two patents both use mechanical ball milling, which has obvious disadvantages: first, impurities are easily introduced during the mechanical ball milling mixing process, affecting the stability of the composition, organization and performance of the binder phase; second, the operation process of the mechanical ball milling method is relatively dangerous. When the ball mill is opened, the fine active powder is prone to spontaneous combustion or even explosion when exposed to air, posing many safety hazards.

[0006] During actual service, the application environment of diamond composites is relatively harsh. For example, in fields such as oil drilling, geological exploration, and grinding machining, there are complex stress and corrosion wear processes, requiring the material to have certain strength and toughness and corrosion resistance. Among nickel-based alloys, nickel-copper alloy (Monel alloy) has extremely strong corrosion resistance, relatively high strength and toughness, and has been widely used in many fields such as marine, machinery, petrochemical, metallurgical engineering, and aerospace. The literature "Tribocorrosion and the surface repassivation behavior of Monel400 alloy in artificial seawater" (Industrial Lubrication and Tribology, 2018, 70(7): 1331-1340) proves through experiments that nickel-copper alloy has better corrosion resistance than elemental nickel or copper. The review "Corrosion aspects of Ni-Cu alloy (UNS N04400) and its surface improvement: a review" (Emergent Materials, 2021, 4(6): 1785-1801) points out that nickel-copper alloy has stronger corrosion resistance than stainless steel and has been used as a cladding material for stainless steel, especially in ship components. The review "Strengthening Mechanisms in Nickel-Copper Alloys: A Review" (Metals, 2020, 10: 1358) points out that nickel-copper alloy has relatively high strength and toughness, certain hardness and wear resistance. Therefore, using nickel-copper alloy as the bonding phase of diamond composites can effectively slow down the corrosion wear and fracture failure behavior of the composites. In addition, as the diamond bonding phase, nickel-copper alloy can effectively inhibit the formation of brittle carbides and improve service stability.

[0007] However, the melting point of traditional nickel-copper alloy is relatively high (about 1350 °C), and the sintering and forming temperature needs to reach at least above 1000 °C. At this temperature, diamond will undergo severe graphitization under the catalytic action of nickel-based alloy, significantly reducing wear resistance and flexural strength, and even causing the material to be unable to form. And traditional nickel-copper alloy has low hardness (115-250 HV) and poor wear resistance (volume wear rate 4.58245×10 -5 mm 3 ·N -1 ·m -1) It is likely to cause premature detachment of diamond during service, reducing the service life. Therefore, it is an urgent problem to be solved to prepare a nickel-copper alloy bonding phase with low melting point, high hardness and high wear resistance, and to prepare a nickel-copper-based diamond composite material with high wear resistance, high bending strength and high impact resistance by regulating the diamond volume fraction, particle size and sintering process parameters, etc. Summary of the Invention

[0008] Aiming at the deficiencies of the prior art, the first object of the present invention is to provide a high-strength, tough and high-wear-resistant nickel-copper-based diamond composite material. By introducing elements such as Si, Mn, B, etc. into the nickel-copper alloy bonding phase powder, the present invention effectively reduces the melting point of the nickel-copper alloy. Through enhanced solid solution strengthening and fine grain strengthening, and introducing second-phase strengthening, the hardness and wear resistance of the nickel-copper alloy are improved. At the same time, the introduction of B element is beneficial to improving the wettability of the nickel-copper alloy to diamond, thereby improving the processability of the composite material. In addition, through the reasonable matching of the amounts of the nickel-copper alloy bonding phase powder and diamond powder, the designed composite material has a bending strength of up to 1080.45 MPa and an impact toughness of up to 2.565 J / cm 2 , and the wear ratio is as high as 1412.2774.

[0009] The second object of the present invention is to provide a preparation method of a high-strength, tough and high-wear-resistant nickel-copper-based diamond composite material. This method is carried out under normal pressure throughout the process, with a simple process flow, a short production cycle, reduced production costs, and does not involve dangerous operations such as mechanical ball milling method, and is suitable for industrial production.

[0010] The third object of the present invention is to provide an application of a high-strength, tough and high-wear-resistant nickel-copper-based diamond composite material. When this composite material is used as a raw material for drilling tools, tooling and grinding tools, it can significantly improve its wear resistance and extend the service life of each tool.

[0011] To achieve the above technical objects, the present invention provides a high-strength, tough and high-wear-resistant nickel-copper-based diamond composite material, which comprises 75-95 vol.% of nickel-copper alloy bonding phase powder and 5-25 vol.% of diamond powder.

[0012] The nickel-copper alloy bonding phase powder in the composite material of the present invention has the advantages of low melting point, high hardness, high wear resistance and high corrosion resistance. When it is used as the bonding phase of diamond powder, it can effectively slow down the corrosion wear and fracture failure behavior of the composite material, and at the same time effectively inhibit the formation of brittle carbides, improving the service stability of the material. The diamond powder in the composite material has extremely high hardness and wear resistance, and the dosage ratio of diamond powder and nickel-copper alloy bonding phase powder is very important. Only when the ratio of the two is within the range selected in the present invention, the designed metal matrix diamond composite material has high flexural strength, high impact toughness and high wear resistance. The inventor found that in actual operation, when the diamond content is low, the diamond cannot provide more hard particles to resist wear, nor can it form a uniform and dense structure in distribution to provide high wear resistance, flexural strength and impact toughness. Appropriately increasing the dosage of diamond can improve the comprehensive performance of the composite material, but when the diamond volume fraction exceeds a certain threshold, the voids between particles decrease, the holding force of the metal matrix on the diamond decreases, and the diamond is more likely to fall off. Moreover, the diamond is more likely to aggregate and accumulate in distribution, exacerbating the problems of local stress concentration and crack propagation, which will reduce the wear resistance, flexural strength and impact toughness of the composite material. Further preferably, the composite material comprises 80-90 vol.% of nickel-copper alloy bonding phase powder and 10-20 vol.% of diamond powder.

[0013] As a preferred embodiment, the nickel-copper alloy bonding phase powder is composed of the following components by mass percentage: Cu 27-28%, Si 3-4%, Mn 0.5-1.5%, B 1.5-2.0%, the balance being Ni, and Cu / (Ni + Cu) being 0.29-0.3.

[0014] The mechanism of high strength, toughness and high wear resistance of the composite material in the present invention lies in: through theoretical calculation, it is found that when Cu / (Ni + Cu) in the nickel-copper alloy is 0.29-0.3 by mass fraction, the alloy has the best corrosion resistance and the highest strength. On this basis, by adding appropriate amounts of Si, Mn, and B elements, the melting point of the nickel-copper alloy bonding phase can be reduced to 947-1015 °C (significantly lower than the original melting point of 1295-1367 °C), which can effectively inhibit the graphitization behavior of diamond during the high-temperature forming process of the composite material, increasing the processability of the composite material. The introduction of Si and Mn elements can also play a role in improving solid solution strengthening, and Si and B elements can form dispersion strengthening phases to help refine grains, improve the hardness of the alloy, and reduce the wear rate. In particular, the doping of an appropriate amount of B element reduces the electrochemical corrosion potential, forming a large number of second phases to promote the passivation behavior of the surface film during the corrosion process, and further improving the corrosion resistance of the alloy through passivation (the corrosion rate is reduced from 0.029915 mm·a -1 to 0.016175 mm·a -1) In addition, in traditional copper-based diamond composites, the wettability between the metal and diamond is poor, the interfacial energy is relatively high, and a large number of defects are easily formed at the interface junction. The doping of element B also helps to improve the interfacial structure between the metal matrix and diamond, enhance the bonding force and thermal conductivity, and contribute to further improving the service efficiency of drilling tools. However, the contents of Si, Mn, and B in the nickel-copper alloy should not be too high, otherwise the bonding phase will be too brittle to be formed. On the basis of doping Si, Mn, and B elements, the continued doping of P element can significantly improve the hardness and wear resistance of the nickel-copper alloy on the premise of slightly sacrificing the corrosion resistance of the nickel-copper alloy. However, the doping of P element will promote the volatilization phenomenon during the gas atomization powder preparation process, increase the preparation difficulty, and is not conducive to large-scale industrial production and application. Since diamond is introduced as the reinforcement phase in the examples of the present invention, the wear resistance of the material is significantly improved, so that the nickel-copper-based diamond composite material without doping P element can also meet the requirements of high strength, high toughness, and high wear resistance. To reduce environmental pollution and ensure the stability of the material composition and preparation process, P element cannot be introduced in the examples of the present invention.

[0015] As a preferred solution, the diamond grade is D grade, and the particle size range is 170 - 200 mesh. When the diamond particle size is too small or the grade is too low, agglomeration and accumulation are likely to occur, and graphitization is more likely to occur, resulting in a decrease in the flexural strength, impact toughness, and wear resistance of the composite material. However, when the diamond particle size is too large, the specific surface area is small, the diamond is easy to fall off, and the preparation cost increases significantly.

[0016] As a preferred solution, the diamond surface is coated with a nickel coating, and the weight gain of the nickel coating is 30 - 60%. In the present invention, as long as the requirements of the weight gain of the transition layer, uniform coating, and good bonding are met, the preparation method of the transition layer is not limited. For example, one of electroplating, electroless plating, evaporation plating, magnetron sputtering, chemical vapor deposition, and physical vapor deposition in the prior art can be used. The electroless nickel plating process on the diamond surface is now very mature, can be mass-produced, and has a low cost. Through the nickel coating, the interfacial bonding between the diamond and the matrix alloy can be enhanced, and the performance of the composite material can be further improved.

[0017] As a preferred solution, the nickel-copper alloy bonding phase powder is prepared by gas atomization. This method has a low cost and can obtain a large number of powders with a high sphericity. The prepared powders have high fluidity and formability, which is beneficial to improving the uniformity of the composite material performance and avoiding potential safety hazards in the mechanical ball milling method.

[0018] As a preferred solution, in the preparation of the nickel-copper alloy bonding phase powder in the present invention, the elemental raw materials of Ni, Cu, Si, Mn, and B are first melted into an alloy ingot and then gas atomized into spherical powders. This can make the distribution of each component in the final atomized powder more uniform.

[0019] As a preferred solution, the Ni, Cu, Si, Mn, and B elements in the raw materials are all added using high-purity elemental raw materials with a purity greater than 99.9%.

[0020] The present invention also provides a method for preparing a high-strength, high-toughness, and high-wear-resistant nickel-copper-based diamond composite material, which is characterized in that: the required nickel-copper alloy binder phase powder and diamond powder are weighed according to the configured ratio, mixed, pre-pressed and deformed, and then hot-pressed and sintered to obtain the composite material.

[0021] As a preferred solution, the mixing is carried out by an acoustic resonance method with an acceleration of 40 - 55g and a time of 4 - 6min. The acoustic resonance method can quickly achieve efficient and uniform mixing of ultrafine powders and materials with large density differences, and avoid safety accidents and introduced impurities that may occur in the mechanical ball milling method.

[0022] As a preferred solution, the pressure of the pre-pressing deformation is controlled at 20 - 45MPa.

[0023] As a preferred solution, the hot-pressing sintering is specifically as follows: First, evacuate to 5 - 50Pa, then heat from room temperature to 380 - 400°C at a heating rate of 80 - 120°C / min, hold for 2 - 3min, and simultaneously apply pressure to the forming pressure of 30 - 50MPa; then heat at a heating rate of 80 - 120°C / min to 665 - 785°C, and then heat to the sintering temperature of 775 - 875°C at a heating rate of 40 - 55°C / min, and hold for 8 - 16min. The heating rate, holding time, and forming pressure of the hot-pressing sintering of the present invention will all affect the properties of the material. If the heating rate is too slow or the holding time is too long, the grain size will grow, reducing the properties of the composite material, and increasing the production time and cost. If the heating rate is too fast, the actual temperature will exceed the set temperature by a large amount, resulting in overburning. If the holding time is too short, it will be difficult for the pores to close, and the composite material will have a low density and poor properties. When the forming pressure of the present invention is too low, the bonding between the powders will be weakened, and it will be difficult for the pores to close, and even the composite material cannot be formed. However, when the forming pressure is too high, the graphite mold and equipment are easily damaged, increasing the production cost, and even possibly causing safety accidents. In addition, the sintering temperature also has an important impact on the properties of the composite material. When the sintering temperature is too high, the graphitization trend of the diamond increases, and the matrix alloy grains grow significantly, and even melting may occur, resulting in the material sticking to the graphite mold and being unable to be demolded. However, when the sintering temperature is too low, the bonding between the powders is weakened, and it is difficult for the pores to close, resulting in poor properties of the composite material and even inability to form. Further preferably, the forming pressure is 40 - 50MPa, and the sintering temperature is 825 - 850°C.

[0024] The flexural strength of the nickel-copper-based diamond composite material designed and prepared by the present invention is not less than 420.97MPa, and the impact toughness is not less than 0.958J / cm2 , the wear ratio is not less than 98.9031.

[0025] After comprehensive optimization of the composition and preparation process, the flexural strength of the composite material prepared by the design of the present invention is not less than 925.19 MPa, and the impact toughness is not less than 2.175 J / cm 2 , the wear ratio is not less than 728.2470.

[0026] The present invention also provides an application of a high-strength, high-toughness and high-wear-resistant nickel-copper-based diamond composite material. When it is used as a raw material for drilling tools, industrial molds and grinding tools, it can significantly improve its wear resistance and extend the service life of each tool.

[0027] Beneficial technical effects brought by the technical solution of the present invention compared with the prior art:

[0028] 1) The present invention uses nickel-copper alloy as the bonding phase matrix of the diamond composite material, introducing a new bonding phase system into the field of diamond composite materials. Compared with the traditional copper-based bonding phase, the nickel-based alloy has stronger wettability to diamond. The nickel-copper alloy has extremely high corrosion resistance and good strength and plasticity, improving the interfacial bonding force between diamond and the metal matrix and enhancing the comprehensive flexural, impact and wear resistance of the composite material.

[0029] 2) The present invention dopes Si, Mn, and B elements into the nickel-copper alloy bonding phase, reducing the melting point of the nickel-copper alloy and inhibiting the graphitization behavior of diamond during the forming process of the composite material, enabling the successful preparation of the nickel-copper-based diamond composite material. At the same time, by enhancing the solid solution strengthening, fine grain strengthening and second phase strengthening effects, the hardness and wear resistance of the matrix alloy are improved, which helps to improve the holding force of the alloy matrix to diamond during service, thus preparing a high-strength, high-toughness and high-wear-resistant diamond composite material. The doped and modified nickel-copper alloy is an ideal material to replace the traditional copper-based bonding phase.

[0030] 3) The present invention uses the acoustic resonance method to mix powders and adopts the rapid hot pressing sintering process to prepare the nickel-copper-based diamond composite material. This method is carried out under normal pressure throughout the process, with a simple process flow, a short production cycle, reduced production costs, and does not involve dangerous operations such as mechanical ball milling method, being suitable for industrial production.

[0031] 4) The wear resistance of the nickel-copper-based diamond composite material of the present invention far exceeds that of the nickel-copper alloy, and maintains a flexural strength and impact toughness equivalent to that of the nickel-copper alloy. This composite material has comprehensive properties of high strength, high toughness and high wear resistance.

[0032] 5) The present invention provides an application of a high-strength, high-toughness and high-wear-resistant nickel-copper-based diamond composite material. When this composite material is used as a raw material for drilling tools, industrial molds and grinding tools, it can significantly improve its wear resistance and extend the service life of each tool. Description of the Drawings

[0033] Figure 1 Morphology of diamond in the composite material of Example 3

[0034] Figure 2 Morphology of diamond in the composite material of Example 5

[0035] Figure 3 Cross-sectional morphology of the nickel-copper-based diamond composite material prepared in Example 8

[0036] Figure 4 Cross-sectional morphology of the nickel-copper-based diamond composite material prepared in Example 10

[0037] Figure 5 Energy spectrum image at the interface of the nickel-copper-based diamond composite material prepared in Example 10

[0038] Figure 6 Energy spectrum image at the interface of the nickel-copper-based diamond composite material prepared in Comparative Example 8

[0039] Figure 7 Backscattered electron contrast image of the nickel-copper-based diamond composite material prepared in Comparative Example 5

[0040] Figure 8 Backscattered electron contrast image of the nickel-copper-based diamond composite material prepared in Comparative Example 6

[0041] Figure 9 Physical photograph of the nickel-copper-based diamond composite material prepared in Comparative Example 6 before demolding

[0042] Figure 10 Secondary electron contrast image of the nickel-copper-based diamond composite material prepared in Comparative Example 11

[0043] Figure 11 Performance comparison of the composite materials of Examples 2, 5, 7, and 9

[0044] From Figure 1 , Figure 2 it can be seen that the diamond crystal form is complete, the surface is flat, and the ablation marks are not obvious

[0045] After being corroded by aqua regia for the same time Figure 1 the diamond surface in Figure 2 is relatively smooth, while there is still more bonding phase metal adhering to the diamond surface in

[0046] From Figure 3 , Figure 4It can be seen that the fracture behavior of the nickel-copper-based diamond composite material is cleavage brittle fracture. The bonded-phase matrix presents a river-like fracture pattern, accompanied by the shedding and pulling out of diamonds. Figure 3 The diamond shedding pits in Figure 4 are relatively scattered, while

[0047] From Figure 5 and Figure 6 it can be seen that the transitional interface between the diamond and the nickel or nickel-copper alloy is well bonded, and there are almost no interface gaps. This shows that the wettability between the nickel and nickel-copper alloy and the diamond surface is good, which helps to enhance the interface bonding force. Figure 5 There is a nickel plating transition layer in Figure 6 and the nickel-copper alloy is in direct contact with the diamond in

[0048] From Figure 7 and Figure 8 it can be seen that the distribution of diamonds in the nickel-copper alloy is relatively uniform, and the segregation phenomenon is not obvious, which also shows that the wettability between the bonded phase and the diamond interface is good. Figure 7 There are a large number of pores in Figure 8 indicating that when the sintering temperature is low, the pore closure is inhibited, reducing the density of the composite material.

[0049] From Figure 9 it can be seen that when the sintering temperature is high, a liquid phase appears in the nickel-copper alloy-diamond composite material during the forming process. After the liquid metal seeps out of the mold and cools and solidifies, it causes the sample to bond with the mold, which may cause the mold to explode during demolding, posing a danger. This process parameter is not applicable.

[0050] From Figure 10 it can be seen that when using diamond crushed material, the fine diamonds fill the edges of the original atomized powder of the nickel-copper alloy, hindering the sintering densification of the bonded-phase matrix, resulting in the material falling off in clusters during service, and significantly reducing the wear resistance of the composite material.

[0051] From Figure 11 it can be seen that after optimization, Examples 5 and 9 have higher flexural strength, impact toughness and wear ratio, and have the best comprehensive performance. Specific embodiments

[0052] To enable those skilled in the art to better understand the technical solution of the present invention, the following will describe the technical solution completely and in detail in conjunction with the accompanying drawings of the present invention. It should be understood that based on the embodiments shown in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0053] Unless otherwise specifically stated, the raw materials, reagents, instrument and equipment, etc. in the present invention can be purchased from the market or obtained by existing preparation methods. For the preparation and testing methods without specific conditions indicated, they are usually implemented according to conventional conditions or the conditions recommended by the equipment manufacturers.

[0054] Example 1

[0055] 1. Material preparation:

[0056] (1) Prepare nickel-copper alloy powder: First, melt the elemental raw materials of Ni, Cu, Si, Mn, and B into an alloy ingot, and then gas atomize it into spherical powder, with the composition being Ni 65.3 Cu 28 Si4Mn1B 1.7 (wt.%). The purity of the above-mentioned melting raw materials is 99.9% or above.

[0057] (2) Prepare diamond powder: Select D-grade diamonds with a particle size range of 170 - 200 mesh. After degreasing the diamond surface, electroless nickel plating is carried out, with a weight gain of 56%.

[0058] (3) Powder mixing: Mix the nickel-copper alloy powder and diamond powder by acoustic resonance method, with an acceleration of 55g and a time of 4min. Among them, the diamond content is 10 vol.%, and the nickel-copper alloy powder content is 90 vol.%.

[0059] 2. Preparation of nickel-copper-based diamond composite material:

[0060] Fill the above-mentioned nickel-copper alloy - diamond mixed powder into a graphite mold. After pre-pressing under a pressure of 20 MPa, rapid hot pressing sintering is carried out. After evacuating to 12 Pa, the temperature is raised from room temperature to 380 °C at a heating rate of 87.5 °C / min, held for 2 min, and at the same time the pressure is increased to 30 MPa. Then the temperature is raised to 680 °C at a heating rate of 100 °C / min, and then raised to 775 °C at a heating rate of 47.5 °C / min, and held for 10 min.

[0061] Example 2

[0062] 1. Material preparation: The difference in material preparation between this example and Example 1 is only that the nickel-copper alloy powder and diamond powder are mixed by acoustic resonance method with an acceleration of 50g and a time of 5min. Among them, the diamond powder content is 10 vol.%, and the nickel-copper alloy powder content is 90 vol.%, and the other conditions are the same.

[0063] 2. Preparation of nickel - copper - based diamond composite materials:

[0064] Fill the above - mentioned nickel - copper alloy - diamond mixed powder into a graphite mold. After pre - pressing under a pressure of 38 MPa, perform rapid hot - press sintering. After evacuating to 26 Pa, heat from room temperature to 400 °C at a heating rate of 92.5 °C / min, hold for 2 min, and simultaneously apply a pressure of 50 MPa. Then heat to 675 °C at a heating rate of 91.7 °C / min, and then heat to 775 °C at a heating rate of 50 °C / min, and hold for 10 min.

[0065] Example 3

[0066] 1. Material preparation is the same as that in Example 2.

[0067] 2. Preparation of nickel - copper - based diamond composite materials:

[0068] Fill the above - mentioned nickel - copper alloy - diamond mixed powder into a graphite mold. After pre - pressing under a pressure of 40 MPa, perform rapid hot - press sintering. After evacuating to 8 Pa, heat from room temperature to 400 °C at a heating rate of 96.67 °C / min, hold for 3 min, and simultaneously apply a pressure of 50 MPa. Then heat to 700 °C at a heating rate of 100 °C / min, and then heat to 800 °C at a heating rate of 50 °C / min, and hold for 10 min.

[0069] Example 4

[0070] 1. Material preparation: The difference in material preparation between this example and Example 2 is only that the mixing time using the acoustic resonance method is replaced by 6 min, and the other conditions are the same.

[0071] 2. Preparation of nickel - copper - based diamond composite materials:

[0072] Fill the above - mentioned nickel - copper alloy - diamond mixed powder into a graphite mold. After pre - pressing under a pressure of 35 MPa, perform rapid hot - press sintering. After evacuating to 25 Pa, heat from room temperature to 400 °C at a heating rate of 95 °C / min, hold for 2 min, and simultaneously apply a pressure of 50 MPa. Then heat to 730 °C at a heating rate of 110 °C / min, and then heat to 825 °C at a heating rate of 47.5 °C / min, and hold for 10 min.

[0073] Example 5

[0074] 1. Material preparation: The difference in material preparation between this example and Example 1 is only that the mixing time using the acoustic resonance method is replaced by 5 min, and the other conditions are the same.

[0075] 2. Preparation of nickel - copper - based diamond composite materials:

[0076] The above nickel - copper alloy - diamond mixed powder was filled into a graphite mold. After pre - pressing under a pressure of 40 MPa, rapid hot - pressing sintering was carried out. After evacuating to 32 Pa, the temperature was raised from room temperature to 400 °C at a heating rate of 100 °C / min, held for 2 min, and at the same time the pressure was increased to 50 MPa. After raising the temperature to 750 °C at a heating rate of 87.5 °C / min, the temperature was raised to 850 °C at a heating rate of 50 °C / min and held for 10 min.

[0077] Example 6

[0078] 1. The material preparation is the same as that in Example 1.

[0079] 2. Preparation of nickel - copper - based diamond composite material:

[0080] The nickel - copper alloy - diamond mixed powder was filled into a graphite mold. After pre - pressing under a pressure of 38 MPa, rapid hot - pressing sintering was carried out. After evacuating to 22 Pa, the temperature was raised from room temperature to 400 °C at a heating rate of 93.8 °C / min, held for 2 min, and at the same time the pressure was increased to 50 MPa. After raising the temperature to 780 °C at a heating rate of 95 °C / min, the temperature was raised to 875 °C at a heating rate of 47.5 °C / min and held for 10 min.

[0081] Example 7

[0082] 1. Material preparation: The difference in material preparation between this example and Example 1 is only that the nickel - copper alloy powder and diamond powder are mixed by acoustic resonance method with an acceleration of 45 g and a time of 5 min. Among them, the content of diamond powder is 5 vol.%, the content of nickel - copper alloy powder is 95 vol.%, and the other conditions are the same.

[0083] 2. Preparation of nickel - copper - based diamond composite material:

[0084] The nickel - copper alloy - diamond mixed powder was filled into a graphite mold. After pre - pressing under a pressure of 40 MPa, rapid hot - pressing sintering was carried out. After evacuating to 13 Pa, the temperature was raised from room temperature to 400 °C at a heating rate of 105 °C / min, held for 2 min, and at the same time the pressure was increased to 50 MPa. After raising the temperature to 750 °C at a heating rate of 87.5 °C / min, the temperature was raised to 850 °C at a heating rate of 50 °C / min and held for 10 min.

[0085] Example 8

[0086] 1. Material preparation: The difference in material preparation between this example and Example 1 is only that the nickel - copper alloy powder and diamond powder are mixed by acoustic resonance method with an acceleration of 50 g and a time of 5 min. Among them, the content of diamond powder is 15 vol.%, the content of nickel - copper alloy powder is 85 vol.%, and the other conditions are the same.

[0087] 2. Preparation of nickel - copper - based diamond composite material:

[0088] Fill the above - mentioned nickel - copper alloy - diamond mixed powder into a graphite mold. After pre - pressing under a pressure of 42 MPa, perform rapid hot - pressing sintering. After evacuating to 10 Pa, heat from room temperature to 400 °C at a heating rate of 92.5 °C / min, hold for 3 min, and simultaneously apply a pressure of 50 MPa. Then heat to 750 °C at a heating rate of 116.7 °C / min, and then heat to 850 °C at a heating rate of 50 °C / min, and hold for 10 min.

[0089] Example 9

[0090] 1. Material preparation: The difference in material preparation between this example and Example 1 is only that the nickel - copper alloy powder and diamond powder are mixed by acoustic resonance method with an acceleration of 50 g and a time of 6 min. Among them, the content of diamond powder is 20 vol.%, the content of nickel - copper alloy powder is 80 vol.%, and the other conditions are the same.

[0091] 2. Preparation of nickel - copper - based diamond composite material:

[0092] Fill the nickel - copper alloy - diamond mixed powder into a graphite mold. After pre - pressing under a pressure of 38 MPa, perform rapid hot - pressing sintering. After evacuating to 15 Pa, heat from room temperature to 400 °C at a heating rate of 110 °C / min, hold for 2 min, and simultaneously apply a pressure of 50 MPa. Then heat to 740 °C at a heating rate of 85 °C / min, and then heat to 850 °C at a heating rate of 55 °C / min, and hold for 10 min.

[0093] Example 10

[0094] 1. Material preparation: The difference in material preparation between this example and Example 1 is only that the nickel - copper alloy powder and diamond powder are mixed by acoustic resonance method with an acceleration of 55 g and a time of 6 min. Among them, the content of diamond powder is 25 vol.%, the content of nickel - copper alloy powder is 75 vol.%, and the other conditions are the same.

[0095] 2. Preparation of nickel - copper - based diamond composite material:

[0096] Fill the nickel - copper alloy - diamond mixed powder into a graphite mold. After pre - pressing under a pressure of 42 MPa, perform rapid hot - pressing sintering. After evacuating to 13 Pa, heat from room temperature to 400 °C at a heating rate of 90 °C / min, hold for 2 min, and simultaneously apply a pressure of 50 MPa. Then heat to 750 °C at a heating rate of 87.5 °C / min, and then heat to 850 °C at a heating rate of 50 °C / min, and hold for 10 min.

[0097] Example 11

[0098] 1. The material preparation is the same as that in Example 2

[0099] 2. Preparation of nickel-copper-based diamond composite material:

[0100] Fill the nickel-copper alloy-diamond mixed powder into a graphite mold. After pre-pressing under a pressure of 40 MPa, rapid hot-pressing sintering is carried out. After evacuating to 20 Pa, heat is raised from room temperature to 400 °C at a heating rate of 100 °C / min, and kept warm for 3 min while pressurizing to 50 MPa. After raising the temperature to 750 °C at a heating rate of 116.7 °C / min, then raise the temperature to 850 °C at a heating rate of 50 °C / min and keep warm for 15 min.

[0101] Comparative Example 1

[0102] The difference between this comparative example and Example 7 is only that the diamond reinforcing phase is not added, that is, the diamond powder content is 0 vol.%, and the nickel-copper alloy powder content is 100 vol.%, and the other conditions are the same.

[0103] Comparative Example 2

[0104] The difference in material preparation between this comparative example and Example 10 is only that the nickel-copper alloy powder and diamond powder are mixed by the acoustic resonance method, with an acceleration of 55 g and a time of 6 min. Among them, the diamond powder content is 40 vol.%, and the nickel-copper alloy powder content is 60 vol.%, and the other conditions are the same.

[0105] Comparative Example 3

[0106] The difference between this comparative example and Example 5 is only that in the preparation process of the nickel-copper alloy-diamond composite material, in the last step, the temperature is raised to the sintering temperature of 850 °C at a heating rate of 50 °C / min and kept warm for 5 min, and the other conditions are the same.

[0107] Comparative Example 4

[0108] The difference between this comparative example and Example 5 is only that in the preparation process of the nickel-copper-based diamond composite material, in the last step, the temperature is raised to the sintering temperature of 850 °C at a heating rate of 50 °C / min and kept warm for 20 min, and the other conditions are the same.

[0109] Comparative Example 5

[0110] The difference between this comparative example and Example 2 is only that in the preparation process of the nickel-copper-based diamond composite material, in the last step, the temperature is raised to 750 °C at a heating rate of 50 °C / min and kept warm for 10 min, and the other conditions are the same.

[0111] Comparative Example 6

[0112] The difference between this comparative example and Example 6 is only that in the preparation process of the nickel-copper-based diamond composite material, the temperature is raised to 900 °C at a heating rate of 50 °C / min in the last step and held for 10 min, and the other conditions are the same.

[0113] Comparative Example 7

[0114] Prepare nickel-copper alloy powder: First, melt the elemental raw materials of Ni, Cu, Si, Mn, and B into an alloy ingot, with the composition of Ni 63 Cu 27 Si4Mn1B5 (wt.%). During the cooling stage, the ingot cracked. The broken pieces were remelted into an alloy ingot, and cracking occurred again during cooling. It shows that the nickel-copper alloy bonding phase with this composition does not have formability in the preparation process of the present invention and cannot be prepared and subjected to performance testing. This is due to the excessive boron content, which causes a sharp drop in the plasticity of the alloy.

[0115] Comparative Example 8

[0116] The difference between this comparative example and Example 8 is only that when preparing diamond powder, after degreasing the diamond surface, nickel plating treatment is not carried out, and the other conditions are the same.

[0117] Comparative Example 9

[0118] The difference between this comparative example and Comparative Example 8 is only that when preparing diamond powder, D-grade diamond with a particle size range of 140-170 mesh is used, and the other conditions are the same.

[0119] Comparative Example 10

[0120] The difference between this comparative example and Comparative Example 8 is only that when preparing diamond powder, D-grade diamond with a particle size range of 200-230 mesh is used, and the other conditions are the same.

[0121] Comparative Example 11

[0122] The difference between this comparative example and Comparative Example 8 is only that when preparing diamond powder, diamond crushed material is selected, and the other conditions are the same.

[0123] Comparative Example 12

[0124] Prepare nickel-copper alloy powder: First, melt the elemental raw materials of Ni, Cu, Si, Mn, B, and P into an alloy ingot, with the composition of Ni 61 Cu 26.3 Si4Mn1B 1.7 P6 (wt.%). During the melting process, a large amount of thick smoke appeared, and it was impossible to prepare gas atomized powder. This is due to the promotion of volatilization by doping with more P elements.

[0125] The nickel-copper-based diamond composites prepared in Examples 1 to 11 were cut by laser, polished, and then tested for density, hardness, flexural strength, impact toughness, and wear ratio. The test results are shown in Table 1.

[0126] Table 1 Performance comparison of nickel-copper-based diamond composites prepared in Examples 1 to 11

[0127]

[0128]

[0129] The nickel-copper alloys and nickel-copper-based diamond composites prepared in Comparative Examples 1 to 12 were cut by laser, polished, and then tested for density, hardness, flexural strength, impact toughness, and wear ratio. The test results are shown in Table 2.

[0130] Table 2 Performance comparison of nickel-copper alloys and composites prepared in Comparative Examples 1 to 12

[0131] Sample <![CDATA[Density (g / cm 3 )]]> Hardness (HRA) Flexural strength (MPa) <![CDATA[Impact toughness (J / cm 2 )]]> Wear ratio Comparative example 1 8.2501 76.13 1361.13 2.217 0.5202 Comparative example 2 6.8711 72.27 343.00 1.211 529.3469 Comparative example 3 7.8128 76.06 - - 608.1192 Comparative example 4 7.8538 75.16 - - 445.7293 Comparative example 5 7.6017 72.28 361.98 0.667 433.8390 Comparative example 6 7.7274 72.60 747.80 1.598 372.2273 Comparative example 7 - - - - - Comparative example 8 7.6398 76.23 924.09 2.121 584.1648 Comparative example 9 7.6036 76.00 864.38 2.001 733.6591 Comparative example 10 7.5957 76.20 1056.61 2.265 493.4039 Comparative example 11 7.6213 76.93 775.66 1.204 7.4455 Comparative example 12 - - - - -

[0132] The comprehensive analysis of Table 1 and Table 2 is as follows:

[0133] Compared with Example 1, Example 2 significantly improved the flexural strength and impact toughness of the composite material while maintaining high wear resistance, indicating that increasing the forming pressure during sintering can accelerate pore closure, improve the bonding force between the binder phase and diamond, and enhance the strength and toughness of the composite material.

[0134] Compared with Example 2, the flexural strength, impact toughness, and wear ratio of Example 3 were further improved, indicating that increasing the sintering temperature to 800 °C helps to promote pore closure and interfacial bonding, and further improve the strength, toughness, and wear resistance of the composite material.

[0135] Compared with Example 3, the flexural strength, impact toughness, and wear ratio of Example 4 were further improved, indicating that increasing the sintering temperature to 825 °C helps to promote pore closure and interfacial bonding, and further improve the strength, toughness, and wear resistance of the composite material.

[0136] Compared with Example 4, the impact toughness of Example 5 was basically the same, while the flexural strength and wear ratio were further improved, indicating that increasing the sintering temperature to 850 °C helps to promote pore closure and interfacial bonding, and further improve the strength, toughness, and wear resistance of the composite material.

[0137] Compared with Example 5, the flexural strength and impact toughness of Example 6 were basically the same, while the wear ratio decreased slightly, indicating that increasing the sintering temperature to 875 °C promoted grain growth and diamond graphitization behavior, and to a certain extent reduced the wear resistance of the composite material.

[0138] Compared with Comparative Example 1, the wear of Example 7 is relatively high, indicating that the diamond reinforcement phase significantly improves the wear resistance of the material. However, compared with Example 5, the flexural strength, impact toughness, and wear ratio of Example 7 all decrease. This is because the low diamond content results in a lack of hard phases to bear the load, inhibiting the improvement of the strength, toughness, and wear resistance of the composite material.

[0139] Compared with Example 7, the flexural strength, impact toughness, and wear ratio of Example 8 all increase, indicating that increasing the diamond content to 15 vol.% helps to improve the strength, toughness, and wear resistance of the composite material.

[0140] Compared with Example 8, the flexural strength of Example 9 slightly decreases, but the impact toughness and wear ratio both increase. In particular, the significant increase in the wear ratio indicates that increasing the diamond content to 20 vol.% helps to significantly improve the wear resistance of the composite material.

[0141] Compared with Example 9, the flexural strength, impact toughness, and wear ratio of Example 10 all slightly decrease, indicating that further increasing the diamond content is not conducive to further improving the performance of the composite material.

[0142] The flexural strength and impact toughness of Example 11 are basically equivalent to those of Comparative Example 10; the wear ratio is basically equivalent to that of Comparative Example 9; the strength, toughness, and wear resistance of Example 11 are significantly higher than those of Comparative Example 8, balancing the contradiction between strength-toughness and wear resistance in Comparative Examples 9 - 11.

[0143] Compared with Example 7, Comparative Example 1 lacks the diamond reinforcement phase, and the wear resistance of the composite material significantly decreases.

[0144] Compared with Example 10, the diamond volume fraction in Comparative Example 2 is extremely high, resulting in a decrease in the comprehensive performance of the composite material. This is because when the diamond content is too high, the agglomeration of diamonds will cause stress concentration, promoting crack initiation and propagation.

[0145] Compared with Example 5, the sintering time of Comparative Example 3 is too short, and the interfacial bonding between the binder phase and diamond is weak, resulting in the composite material hardly having flexural strength and impact toughness and being unsuitable for use as raw materials for drill bits, tooling, and grinding tools.

[0146] Compared with Example 5, the sintering time of Comparative Example 4 is too long, and the abnormal growth of the binder phase grains leads to a low load-bearing capacity of the matrix, resulting in the direct fracture of the composite material during the preparation process, without detectable flexural strength and impact toughness, and being unsuitable for use as raw materials for drill bits, tooling, and grinding tools.

[0147] Compared with Example 3, the sintering temperature of Comparative Example 5 is relatively low, the pores have no time to close, and the interfacial bonding between the matrix and diamond is weak, resulting in poor comprehensive performance of the composite material.

[0148] Compared with Example 6, the sintering temperature of Comparative Example 6 was higher, and severe graphitization of diamond occurred, resulting in lower flexural strength and impact toughness, and a significant decrease in wear resistance. It is worth noting that during the sintering process, a small amount of liquid phase also appeared in Comparative Example 6, which aggravated the uneven distribution of diamond in the composite material and was not conducive to the performance stability of the sample. The liquid phase seeped out of the mold, which also caused the adhesion between the sample and the mold, and might lead to the explosion of the mold during the demolding process, triggering a safety accident. Therefore, the process parameters of this comparative example cannot be used for industrial production. The present invention uses a nickel-copper alloy as the diamond bonding phase. The nickel-copper alloy has good wettability with diamond, and plating a nickel coating can further increase the bonding force between diamond and the bonding phase, further improving the comprehensive performance of the composite material. However, as can be seen from Comparative Example 6, under the catalytic action of nickel and nickel-copper alloy, obvious graphitization of diamond occurred at a relatively low temperature (900 °C), resulting in the loss of flexural strength and wear resistance of the composite material. At this time, the temperature did not reach the sintering and forming temperature range of traditional nickel-copper alloy, and it was impossible to inhibit the graphitization of diamond while achieving the densification of traditional nickel-copper alloy. This shows that it is necessary to introduce low contents of Si, Mn, and B element doping into the nickel-copper alloy in the present invention to reduce the melting point of the bonding phase alloy, so as to lower the optimized forming temperature range to 825 - 850 °C, which helps to simultaneously improve the strength and toughness and wear ratio of nickel-based diamond composites.

[0149] Compared with Example 8, the flexural strength, impact toughness, and wear ratio of Comparative Example 8 all decreased slightly, indicating that nickel plating treatment helps to improve the interfacial bonding strength between diamond and the bonding phase, and plating a nickel coating on the diamond surface improves the flexural, impact, and wear resistance of the composite material.

[0150] Compared with Comparative Example 8, the flexural strength and impact toughness of Comparative Example 9 decreased slightly, but the wear ratio increased significantly, indicating that the increase in diamond particle size is beneficial to further improving the wear resistance of the composite material, but it will lead to weak interfacial bonding, thus inhibiting the improvement of flexural strength and impact toughness.

[0151] Compared with Comparative Example 8, the flexural strength and impact toughness of Comparative Example 10 increased, but the wear ratio decreased slightly, indicating that the decrease in diamond particle size is not conducive to further improving the wear resistance of the composite material, but it will lead to enhanced interfacial bonding, thus improving the flexural strength and impact toughness of the composite material.

[0152] Compared with Comparative Example 8, diamond crushed material was used in Comparative Example 11. This kind of diamond has low quality and low wear resistance itself, and the fine crushed material is dispersed around the nickel-copper powder, inhibiting the sintering densification of the bonding phase matrix, resulting in extremely low wear resistance of the composite material.

[0153] Test Example 1 Density Test

[0154] The MSA324S-000-DU type densitometer was used to conduct density tests according to the principle of Archimedes' drainage method. A diamond grinding wheel was used to remove the contaminated layer on the surface of the sintered sample, and deionized water was used as the solution medium to measure and calculate the density of the sample.

[0155] Test Example 2 Hardness Test

[0156] An HRA hardness test was conducted using a digital display Rockwell hardness tester. Samples with a single side not less than 10 mm were cut from the composite material by laser cutting process. After grinding to 2000 mesh with a diamond sand disc, they were polished to a mirror surface using W1.5 diamond spray. The selected test conditions were a diamond indenter, a loading load of 588 N, and a holding time of 6 s.

[0157] Test Example 3 Flexural Test

[0158] A three-point flexural test was conducted using an Instron 3369 type electronic universal material testing machine. Samples of 35×4×3 mm were cut from the composite material by laser cutting process and ground to 180 mesh with a diamond sand disc. The selected test span was 25 mm and the loading speed was 1 mm / min.

[0159] Test Example 4 Impact Test

[0160] An impact test was conducted using an LZ21.251-AZ type pendulum impact testing machine. Samples of 35×5×5 mm were cut from the composite material by laser cutting process and ground to 180 mesh with a diamond sand disc. The selected test span was 25 mm and the energy was 25 J.

[0161] Test Example 5 Abrasion Ratio Test

[0162] The abrasion ratio test was conducted according to JB / T 3235-2013. Samples with a single side not less than 15 mm were cut from the composite material by laser cutting process and ground to 180 mesh with a diamond sand disc. The selected test conditions were a grinding wheel speed of 25 m / s and a grinding time of 192 s.

[0163] Test Example 6 Microstructure Characterization

[0164] The microstructure of the sample was observed using a MIRA4LMH type scanning electron microscope equipped with an Ultim Max 40 type energy spectrometer. Samples with a single side not less than 10 mm were cut from the composite material by laser cutting process. After grinding to 2000 mesh with a diamond sand disc, they were polished to a mirror surface using W1 diamond spray.

[0165] In summary, the present invention has the following advantages:

[0166] For the first time, nickel-copper alloy is used as the diamond bonding phase. By regulating sintering process parameters, diamond content, etc., while ensuring the formability of nickel-copper-based diamond composites, a new type of diamond composite material with high flexural strength, impact toughness and wear ratio is designed and prepared, meeting the comprehensive requirements for flexural strength, impact toughness and wear resistance of diamond composites in various fields such as oil drilling, geological exploration, grinding and machining. The preparation process of the present invention is simple, fast, safe, easy to realize industrial production, and can be applied to various fields such as drilling tools, industrial molds and grinding tools.

[0167] It should be understood that the present invention should not be limited to these embodiments shown in this specification, but should conform to the widest scope consistent with the innovation disclosed by the present invention.

Claims

1. A preparation method of a high-strength, high-toughness and high-wear-resistant nickel-copper-based diamond composite material, characterized in that: Weigh the required nickel-copper alloy binder phase powder and diamond powder according to the configuration ratio, mix them, carry out pre-press deformation, and then use hot press sintering to obtain it; The nickel-copper-based diamond composite material comprises 75-95 vol.% nickel-copper alloy binder phase powder and 5-25 vol.% diamond powder; The nickel-copper alloy binder phase powder is composed of the following components by mass percentage: Cu 27-28%, Si 3-4%, Mn 0.5-1.5%, B 1.5-2.0%, the balance is Ni, and Cu / (Ni + Cu) is 0.29-0.3; The particle size range of the diamond powder is 170-200 mesh; The specific hot press sintering process is as follows: First, evacuate to 5-50 Pa, then heat from room temperature to 380-400 °C at a heating rate of 80-120 °C / min, keep warm for 2-3 min, and at the same time apply pressure to the forming pressure of 40-50 MPa; Then heat to 665-785 °C at a heating rate of 80-120 °C / min, and then heat to the sintering temperature of 825-850 °C at a heating rate of 40-55 °C / min, and keep warm for 8-16 min.

2. The preparation method of a high-strength, high-toughness and high-wear-resistant nickel-copper-based diamond composite material according to claim 1, characterized in that: The grade of the diamond is grade D.

3. The preparation method of a high-strength, high-toughness and high-wear-resistant nickel-copper-based diamond composite material according to claim 2, characterized in that: The surface of the diamond is coated with a nickel plating layer.

4. The preparation method of a high-strength, high-toughness and high-wear-resistant nickel-copper-based diamond composite material according to claim 1 or 2, characterized in that: The nickel-copper alloy binder phase powder is prepared by gas atomization method.

5. The preparation method of a high-strength, high-toughness and high-wear-resistant nickel-copper-based diamond composite material according to claim 4, characterized in that: The mixing adopts the acoustic resonance method with an acceleration of 40-55 g and a time of 4-6 min.

6. The preparation method of a high-strength, high-toughness and high-wear-resistant nickel-copper-based diamond composite material according to claim 5, characterized in that: The pressure of the pre-press deformation is controlled at 20-45 MPa.

7. The application of the high-strength, high-toughness and high-wear-resistant nickel-copper-based diamond composite material prepared by the preparation method according to any one of claims 1 to 6, characterized in that: It is used as a raw material for drill tools.

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