Porous metal-based diamond tool and method of making same

Abstract

The application discloses a kind of porous metal-based diamond tools and preparation method thereof, it is related to diamond tool technical field.The porous structure is included in the substrate including solid structure, solid region in substrate includes metal and diamond, the volume ratio of diamond and metal is 10-30:70-90;Metal includes copper, low melting point metal and titanium hydride, and the mass ratio of copper, low melting point metal and titanium hydride is 75-85:10-20:2.5-10;Porous structure includes the titanium pore generated by the thermal decomposition of titanium hydride, and the periphery of titanium pore is wrapped low melting point metal, and the melting point of low melting point metal is ≤500 DEG C.The porous metal-based diamond tool prepared by the application has uniform porosity, controllable pore size, less strength loss, and can meet the use requirements of diamond tool matrix.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of diamond tools. Specifically, it relates to a porous metal-based diamond tool and a preparation method and application thereof. BACKGROUND

[0002] Diamond is the hardest material in nature known at present. Diamond tools are processing tools with certain shapes made of artificial diamond as grinding components and with the aid of a binder (resin, metal or ceramic, etc.), and their processing efficiency and applicable range are obviously superior to other tools, and they are known as "industrial teeth". In diamond tools, the organization formed by the binder material after solidification is also called a matrix, which has two main functions: one is to "embed" diamond, i.e. to hold diamond, which determines the service life of the tool; the other is to "match" wear with diamond, i.e. to have a sharp edge, which determines the sharpness or working efficiency of the tool.

[0003] In conventional diamond tools, the holding of diamond by the matrix is mainly mechanical embedding. When the matrix composition is determined, the mechanical embedding force and the density are positively correlated. Therefore, most of the diamond tools on the market are dense tools. However, the pursuit of high density alone often sacrifices the processing efficiency and processing quality of diamond tools. For example, in some working conditions, there are phenomena such as insufficient cooling and difficult heat dissipation, which lead to the failure of diamond abrasive grains due to graphitization or the overburning of the surface of the processing object; the generated grinding dust covers the diamond abrasive grains due to the lack of chip space and chip removal channels, which leads to the decrease of the processing efficiency of the tool, etc.

[0004] With the development of science and technology and society, the requirements for the service performance of diamond tools, especially the processing efficiency, are getting higher and higher. Reasonably introducing pores into the matrix to increase the chip space and cooling effect and to more fully play the grinding function of diamond abrasive grains has become an important means to improve the service performance of diamond tools.

[0005] The methods of introducing porosity into the matrix mainly include low-pressure sintering method and pore-forming agent method. The history of low-pressure sintering method can be traced back to 1991. In 1991, TANAKA Toshio coated a layer of Ni-Cu-Sn metal layer on the surface of diamond by electroplating, and then prepared a porous diamond tool by cold pressing and vacuum sintering. The metal coating layer melts during the sintering process, and then solidifies between adjacent diamonds during the cooling process, forming a binding bridge to connect different diamond particles together. Later, Tomino et al. prepared a cast iron-based porous diamond grinding wheel with a porosity of 20% to 35% by controlling the hot-pressing sintering temperature (640-800℃) at a relatively low hot-pressing pressure of 10 MPa. The pore-forming agent method is a method of generating pores in the matrix by using pore-forming agents. At present, pore-forming agents are mainly divided into three categories. The first category of pore-forming agents is mainly salt, which can form pores by dissolving in solution. The second category of pore-forming agents is mainly organic matter or metal hydride, which will decompose or volatilize at high temperature, thereby forming pores. The third category of pore-forming agents is usually a high-temperature-resistant space-occupying pore-forming agent, which does not change during high-temperature sintering, and breaks or falls off during use, thereby forming a space-occupying pore in the matrix. Compared with the pore-forming agent method, the porous diamond tool prepared by the low-pressure sintering method not only has a lower porosity, but also has a greater strength loss rate, which is about 2-24 times that of the pore-forming agent method. Therefore, the pore-forming agent method is more widely used.

[0006] The initial hydrogen release temperature of titanium hydride is about 390-465℃, which is a typical pyrolytic pore-forming agent, and is initially used to prepare porous aluminum materials. However, the hot-pressing sintering densification temperature of most metal diamond tools is generally above 700℃. There is a relatively obvious mismatch between the decomposition temperature of titanium hydride and the densification temperature of the metal matrix. This temperature mismatch causes the generated hydrogen to escape from the gap between the metal powders, ultimately leading to a decrease or even loss of pore-forming efficiency. In order to reduce this temperature mismatch, some researchers have carried out pre-oxidation treatment on titanium hydride. The higher the oxidation temperature, the thicker the surface oxide layer, and the higher the decomposition temperature of titanium hydride powder. However, pre-oxidation also has some problems, such as the thicker the oxide layer, the less hydrogen remaining in the titanium hydride powder to generate pores; the oxide layer on the surface of titanium hydride is prone to cracking due to stress. Therefore, pre-oxidation has limited actual help for the pore-forming effect of titanium hydride.

[0007] In view of this, the present application is proposed. SUMMARY

[0008] The present application aims to provide a porous metal diamond tool and a preparation method thereof.

[0009] The present application is implemented as follows:

[0010] In a first aspect, the present application provides a porous metal-based diamond tool, comprising a substrate with a porous structure, wherein a solid region in the substrate comprises metal and diamond, and the volume ratio of the diamond to the metal is 10-30:70-90.

[0011] The metal comprises copper, a low-melting-point metal and titanium hydride, and the mass ratio of the copper, the low-melting-point metal and the titanium hydride is 75-85:10-20:2.5-10.

[0012] The porous structure comprises titanium pores generated by thermal decomposition of the titanium hydride, and the low-melting-point metal is wrapped around the periphery of the titanium pores, and the melting point of the low-melting-point metal is ≤500℃.

[0013] In a second aspect, the present application provides a method for preparing the porous metal-based diamond tool according to the preceding embodiment, comprising: mixing the copper, the low-melting-point metal and the titanium hydride in a proportion by ball milling to obtain a metal premixed powder; subjecting the composite powder obtained by mixing the metal premixed powder with diamond to low-temperature high-pressure sintering to be shaped; and then performing high-temperature low-pressure heat treatment to obtain the porous metal-based diamond tool.

[0014] In a third aspect, the present application provides an application of the porous metal-based diamond tool according to the preceding embodiment or the porous metal-based diamond tool prepared by the method according to any one of the preceding embodiments in a porous metal material.

[0015] The present application has the following beneficial effects:

[0016] The present application provides a porous metal-based diamond tool, by adding a low-melting-point metal, the low-melting-point metal is wrapped around the surface of the titanium hydride, when the titanium hydride is heated and decomposed to generate hydrogen, due to the wrapping of the low-melting-point metal, the hydrogen cannot be discharged, thereby generating a porous structure in the substrate. In addition, the titanium hydride is protected by the wrapping effect of the low-melting-point metal, so that the titanium hydride is not easy to release hydrogen in advance, achieving good pore-forming effect, and the addition amount of the titanium hydride is high, so that a rich porous structure can be obtained in the diamond tool. The porous metal-based diamond tool prepared by the present application has uniform pores, controllable pore size and less strength loss, and can meet the use requirements of the matrix of the diamond tool.

[0017] The application further provides a preparation method of the porous metal-based diamond tool, which comprises two steps of sintering. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0019] Figure 1 The scanning electron microscope image of the porous metal-based diamond tool provided in Embodiment 1 of the present application. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described as follows. If the specific conditions are not indicated in the embodiments, the conventional conditions or the conditions suggested by the manufacturers are adopted. If the manufacturers of the reagents or instruments are not indicated, they are all conventional products which can be purchased in the market.

[0021] The features and performances of the present application will be further described in detail in combination with the embodiments.

[0022] In the first aspect, the present application provides a porous metal-based diamond tool, which comprises a base body with a porous structure, and the solid area in the base body comprises metal and diamond, and the volume ratio of the diamond to the metal is 10-30:70-90.

[0023] The metal comprises copper, a low-melting-point metal and titanium hydride, and the mass ratio of the copper, the low-melting-point metal and the titanium hydride is 75-85:10-20:2.5-10.

[0024] The porous structure is a titanium pore produced by thermal decomposition of titanium hydride, and the titanium pore is wrapped by a low-melting-point metal, and the melting point of the low-melting-point metal is ≤500℃.

[0025] In an optional embodiment, the melting point of the low-melting-point metal is ≤500℃.

[0026] Preferably, the low-melting-point metal comprises tin or zinc, and preferably tin.

[0027] In a second aspect, the present application provides a method for preparing the porous metal-based diamond tool as described in the foregoing embodiments, comprising mixing copper, a low-melting-point metal and titanium hydride in a proportion to obtain a metal premixed powder, then sintering and shaping the composite powder obtained by mixing the metal premixed powder and diamond particles at low temperature and high pressure, and then performing high-temperature and low-pressure heat treatment to obtain the porous metal-based diamond tool. The specific steps and related parameters are as follows:

[0028] S01, ball milling

[0029] The copper, the low-melting-point metal and the titanium hydride are put into a planetary ball mill in a proportion to be mixed by ball milling to obtain a metal premixed powder.

[0030] The inventors have found that the initial hydrogen release temperature of titanium hydride is about 465℃, the peak hydrogen release temperature is 540-700℃, and the sintering densification temperature of most diamond tools is above 700℃. This will cause the hydrogen release of titanium hydride to be advanced during the sintering process of the diamond tool, thereby losing the pore-forming effect. In addition, the inventors have also found that during the ball milling process of the copper powder and the titanium hydride, the instantaneous temperature in the ball milling process is too high, which will also cause the hydrogen release of titanium hydride to be advanced, thereby affecting the pore-forming effect. Therefore, the inventors adopt the ball milling mixing of copper, a low-melting-point metal and titanium hydride, which not only can improve the retention rate of titanium hydride, but also can refine the titanium hydride, so that the titanium hydride is uniformly distributed in the matrix, and the activity of the metal powder after ball milling is higher, and the sintering densification is easier.

[0031] In an optional embodiment, the melting point of the low-melting-point metal is ≤500℃, and preferably tin.

[0032] In an optional embodiment, the parameters of the ball milling include a ball-to-material ratio of 5-10:1, a ball milling time of 10-20h, and a ball milling speed of 80-300rpm.

[0033] The inventors have found that the ball-to-material ratio, the ball milling time and the ball milling speed will all affect the refinement degree and retention rate of titanium hydride and the alloying degree of copper-tin; if the energy provided by the ball-to-material ratio, the ball milling time and the ball milling speed is too low, the titanium hydride cannot be effectively wrapped by the low-melting-point metal; if the energy provided by the ball-to-material ratio, the ball milling time and the ball milling speed is too high, the titanium hydride will release hydrogen in the ball milling stage, which will also affect the pore-forming effect.

[0034] In an optional embodiment, the metal premixed powder is further sieved after the ball milling, with a mesh size of ≥200 mesh.

[0035] S02, mixing with diamond

[0036] In an optional embodiment, the metal premixed powder sieved in the step S01 is mixed with diamond in a mixer to obtain a composite powder.

[0037] In an optional embodiment, the rotation speed of the mixer is 80-120 rpm, and the mixing time is 1-3 h.

[0038] S03, low-temperature and high-pressure sintering

[0039] In an optional embodiment, the low-temperature and high-pressure sintering comprises placing the composite powder in step S02 in a mold, and sintering and densifying in a vacuum or inert atmosphere to obtain a metal-titanium hydride-diamond alloy block. The mold can be a high-temperature resistant graphite mold, and the inert atmosphere can be an argon atmosphere, for example.

[0040] Preferably, the parameters of the low-temperature and high-pressure sintering include a sintering temperature of 300-400℃, a sintering pressure of 25-35 MPa, a heating rate of 80-120℃ / min, and a pressure holding time of 10-20 min.

[0041] Under the conditions of low temperature and high pressure, tin is fully diffused at low temperature due to its low melting point. Tin melts at a relatively low temperature (melting point of tin is 231℃), and the liquid tin can promote the rearrangement of metal powder particles, thereby increasing the density of the matrix and wrapping the titanium hydride, so as to obtain a dense copper-tin-titanium hydride alloy block. Since the hydrogen release temperature of titanium hydride is about 390-465℃, the amount of hydrogen released from titanium hydride under the above conditions of low temperature and high pressure is very small, and will not affect the final pore forming effect.

[0042] S04, high-temperature and low-pressure heat treatment

[0043] The metal-titanium hydride-diamond alloy block obtained in step S03 is placed in a box furnace, and the block is heat treated in an argon atmosphere to obtain a porous metal-based diamond tool.

[0044] In an optional embodiment, the parameters of the high-temperature and low-pressure heat treatment include a heat treatment temperature of 600-850℃, preferably 800-850℃, a heat preservation time of 20-40 min, a heat treatment pressure of 0-5 MPa, and a heat treatment environment of vacuum or inert atmosphere. The inert atmosphere can be an argon atmosphere, for example.

[0045] The compact alloy block obtained by the low-temperature sintering in the previous step can concentrate hydrogen release in the high-temperature low-pressure heat treatment process. Since the titanium hydride has been enclosed in a sealed space in the S03 step, the hydrogen released by the titanium hydride cannot escape, thereby realizing the pore-forming effect.

[0046] In a more preferred embodiment, the application provides a method for preparing a porous metal-based diamond tool, which has at least the following advantages:

[0047] 1. The low-melting-point metal added in the application has relatively low strength. In the ball milling process, the low-melting-point metal can be more easily wrapped on the surface of the titanium hydride, reducing the direct effect of thermal energy on the titanium hydride in the ball milling process, reducing the decomposition of the titanium hydride, and allowing more titanium hydride to remain in the high-temperature hydrogen release stage, thereby achieving a better pore-forming effect.

[0048] 2. The method for preparing a porous metal-based diamond tool according to the application adopts a planetary ball milling-two-step sintering process route. The low-melting-point soft tin is used to wrap the titanium hydride to inhibit the decomposition of the titanium hydride in the ball milling process, and the copper-tin-titanium pretreated powder with uniform titanium hydride distribution, controllable particle size and high retention rate is obtained under appropriate ball milling process. The sintering densification at low temperature and high pressure allows the liquid tin to fully diffuse and enclose the titanium hydride in a sealed space. The high-temperature low-pressure heat treatment makes the titanium hydride concentrate hydrogen release, fully forms pores in this stage, and further alloys the copper-tin-titanium, thereby obtaining the porous metal-based diamond tool with uniform pore distribution, controllable pore size and small strength loss.

[0049] 3. The pretreated powder prepared by the method has high sintering activity and is easy to alloy. The porosity can be adjusted by adjusting the component ratio and the preparation process parameters. The pore size is small, the distribution is uniform, and the sphericity is high. With the increase of porosity, the strength loss of the tool is small, and the porous metal-based diamond tool with high strength and high porosity can be prepared.

[0050] 4. Compared with other pore-forming methods, the preparation method of the application has the advantages of low cost, high pore-forming efficiency and high tool strength.

[0051] Example 1

[0052] The embodiment provides a method for preparing a porous metal-based diamond tool, which comprises the following steps:

[0053] S01, ball milling

[0054] Copper, tin and titanium hydride are put into a planetary ball mill in a ratio of 82:15.5:2.5 to be ball milled and mixed, to obtain a metal premixed powder.

[0055] The ball milling parameters of the planetary ball mill include a ball-to-material ratio of 10:1, a ball milling time of 20 h, and a ball milling speed of 300 rpm.

[0056] After the ball milling is completed, the prepared metal premixed powder is sieved for use, and the mesh size of the sieve is 200 meshes.

[0057] S02, mixing with diamond

[0058] The metal premixed powder sieved in the step S01 is mixed with 10 vol.% of diamond in a mixer, the rotating speed of the mixer is 40 rpm, and the mixing time is 2 h, to obtain a composite powder.

[0059] S03, low-temperature and high-pressure sintering

[0060] The composite powder in the step S02 is placed in a graphite mold, and low-temperature and high-pressure sintering is performed under an argon atmosphere, to obtain a copper-tin-titanium hydride-diamond alloy block.

[0061] The parameters of the low-temperature and high-pressure sintering include that the sintering temperature is 350 ℃, the sintering pressure is 30 MPa, the temperature rising rate is 100 ℃ / min, and the pressure maintaining time is 15 min.

[0062] S04, high-temperature and low-pressure heat treatment

[0063] The copper-tin-titanium hydride-diamond alloy block obtained in the step S03 is placed in a box furnace, and block heat treatment is performed under an argon atmosphere, to obtain a porous metal-based diamond tool.

[0064] The parameters of the high-temperature and low-pressure heat treatment include that the heat treatment temperature is 800 ℃, the heat preservation time is 30 min, and the heat treatment pressure is 5 MPa.

[0065] The porous metal-based diamond tool prepared in the embodiment is placed under a scanning electron microscope to observe the microstructure, and the results are shown in FIG. 2. Figure 1 As shown in FIG. 2, the pores in the porous metal-based diamond tool provided in the embodiment have the characteristics of small pore size, uniform distribution, and high sphericity. Figure 1

[0066] Embodiment 2

[0067] The embodiment provides a preparation method of a porous metal-based diamond tool, and the method comprises the following steps.

[0068] S01, ball milling

[0069] Copper, tin and titanium hydride are put into a planetary ball mill in a proportion of 80:15:5 for ball milling mixing, to obtain a metal premixed powder.

[0070] The parameters of the planetary ball mill include that the ball-to-material ratio is 10:1, the ball milling time is 20 h, and the ball milling rotating speed is 300 rpm.

[0071] ​After the ball milling, the prepared metal premixed powder was sieved for use, and the mesh number of the sieve was 200 meshes.

[0072] S02, mixing with diamond

[0073] The metal premixed powder sieved in the step S01 was mixed with 10 vol.% of diamond in a mixer at a rotation speed of 100 rpm for 2 h to prepare a composite powder.

[0074] S03, low-temperature and high-pressure sintering

[0075] The composite powder in the step S02 was placed in a graphite mold and subjected to low-temperature and high-pressure sintering in an argon atmosphere to prepare a copper-tin-titanium hydride-diamond alloy block.

[0076] The parameters of the low-temperature and high-pressure sintering included a sintering temperature of 350℃, a sintering pressure of 30 MPa, a temperature rising rate of 100℃ / min, and a pressure maintaining time of 15 min.

[0077] S04, high-temperature and low-pressure heat treatment

[0078] The copper-tin-titanium hydride-diamond alloy block obtained in the step S03 was placed in a box furnace and subjected to block heat treatment in an argon atmosphere to prepare a porous metal-based diamond tool.

[0079] The parameters of the high-temperature and low-pressure heat treatment included a heat treatment temperature of 800℃, a heat treatment time of 30 min, and a heat treatment pressure of 5 MPa.

[0080] Example 3

[0081] The present embodiment provides a method for preparing a porous metal-based diamond tool, which comprises the following steps:

[0082] S01, ball milling

[0083] Copper, tin and titanium hydride were put into a planetary ball mill in a proportion of 78:14.5:7.5 to be mixed by ball milling, and a metal premixed powder was obtained.

[0084] The parameters of the planetary ball mill included a ball-to-material ratio of 10:1, a ball milling time of 20 h, and a ball milling rotation speed of 300 rpm.

[0085] After the ball milling, the prepared metal premixed powder was sieved for use, and the mesh number of the sieve was 200 meshes.

[0086] S02, mixing with diamond

[0087] The metal premixed powder sieved in the step S01 was mixed with 10 vol.% of diamond in a mixer at a rotation speed of 100 rpm for 2 h to prepare a composite powder.

[0088] S03, low-temperature high-pressure sintering

[0089] The composite powder of the S02 step is placed in a graphite mold, and low-temperature high-pressure sintering is performed under an argon atmosphere to obtain a copper-tin-titanium hydride-diamond alloy block.

[0090] The parameters of the low-temperature high-pressure sintering include a sintering temperature of 350°C, a sintering pressure of 30 MPa, a temperature rising rate of 100°C / min, and a pressure holding time of 15 min.

[0091] S04, high-temperature low-pressure heat treatment

[0092] The copper-tin-titanium hydride-diamond alloy block obtained in the S03 step is placed in a box furnace, and block heat treatment is performed under an argon atmosphere to obtain a porous metal-based diamond tool.

[0093] The parameters of the high-temperature low-pressure heat treatment include a heat treatment temperature of 800°C, a heat preservation time of 30 min, and a heat treatment pressure of 5 MPa.

[0094] Example 4

[0095] The present embodiment provides a method for preparing a porous metal-based diamond tool, comprising the following steps:

[0096] S01, ball milling

[0097] Copper, tin, and titanium hydride are put into a planetary ball mill in a ratio of 76:14:10 for ball milling mixing to obtain a metal premix powder.

[0098] The ball milling parameters of the planetary ball mill include a ball-to-material ratio of 10:1, a ball milling time of 20 h, and a ball milling speed of 300 rpm.

[0099] After the ball milling is completed, the metal premix powder obtained is sieved for use, and the mesh size of the sieve is 200 mesh.

[0100] S02, mixing with diamond

[0101] The metal premix powder sieved in the S01 step is mixed with 10 vol.% of diamond in a mixer for 2 h at a speed of 100 rpm to obtain a composite powder.

[0102] S03, low-temperature high-pressure sintering

[0103] The composite powder of the S02 step is placed in a graphite mold, and low-temperature high-pressure sintering is performed under an argon atmosphere to obtain a copper-tin-titanium hydride-diamond alloy block.

[0104] The parameters of low-temperature high-pressure sintering include: a sintering temperature of 350°C, a sintering pressure of 30 MPa, a temperature rising rate of 100°C / min, and a pressure maintaining time of 15 min.

[0105] S04, high-temperature low-pressure heat treatment

[0106] The copper tin-titanium hydride-diamond alloy block obtained in the S03 step is placed in a box furnace for block heat treatment under an argon atmosphere to obtain a porous metal-based diamond tool.

[0107] The parameters of the high-temperature low-pressure heat treatment include a heat treatment temperature of 800°C, a heat preservation time of 30 min, and a heat treatment pressure of 5 MPa.

[0108] Comparative Example 1

[0109] The method for surface oxidation of titanium hydride adopted in the prior art "Preparation of Porous Brazed Grinding Wheel and Experimental Study on SiC Ceramic Grinding", Liu Wei et al., China Mechanical Engineering, 2022, 33(15): 1787-1793. Specifically as follows:

[0110] A porous diamond tool is prepared using copper tin alloy powder-titanium hydride. In this study, titanium hydride is subjected to oxidation treatment (oxidized at 400°C for 6h, and oxidized at 500°C for 1h) to increase the hydrogen release temperature. The titanium hydride after oxidation treatment is mixed uniformly with copper tin alloy powder, and a forming embryo is obtained by using a molding process of 100 MPa and 15 min. Then, the forming embryo is subjected to vacuum liquid phase sintering under the conditions of 920°C, 5°C / min, and vacuum atmosphere.

[0111] Comparative Example 2

[0112] This comparative example provides a method for preparing a porous metal-based diamond tool. The preparation method is similar to that of Example 1, and the only difference is that the S01 and S02 steps of raw material mixing are different. The specific differences are as follows:

[0113] S01, ball milling

[0114] Copper and titanium hydride are put into a planetary ball mill in proportion to obtain copper-titanium hydride metal premix powder.

[0115] The ball milling parameters of the planetary ball mill include a ball-to-material ratio of 10:1, a ball milling time of 20h, and a ball milling speed of 300rpm.

[0116] After ball milling, the copper-titanium hydride metal premix powder obtained is sieved for use, and the mesh size of the sieve is 200 mesh.

[0117] S02, mixing with tin powder and diamond

[0118] The screened copper-titanium hydride metal premixed powder of step S01 was mixed with tin and diamond in a mixer at a rotation speed of 100 rpm for 2 h to obtain a composite powder.

[0119] In the step S01 and S02, the mass ratio of copper, tin and titanium hydride was 80:15:5, and the amount of diamond was 10 vol. %.

[0120] Comparative Example 3

[0121] This comparative example provides a method for preparing a porous metal-based diamond tool, which is similar to Example 1, except that the step S01 of mixing raw materials is different, and the specific differences are as follows:

[0122] S01, ball milling

[0123] Copper, tin and titanium hydride were put into a planetary ball mill in a ratio of 74:14:12 for ball milling to obtain a metal premixed powder.

[0124] The ball milling parameters of the planetary ball mill include a ball-to-material ratio of 10:1, a ball milling time of 20 h, and a ball milling speed of 300 rpm.

[0125] After ball milling, the obtained metal premixed powder was screened for use, and the mesh size of the screen was 200 mesh.

[0126] Comparative Example 4

[0127] This comparative example provides a method for preparing a porous metal-based diamond tool, which is similar to Example 1, except that the step S01 of mixing raw materials is different, and the specific differences are as follows:

[0128] Copper, tin and titanium hydride were put into a planetary ball mill in a ratio of 80:15:5 for ball milling to obtain a metal premixed powder.

[0129] The ball milling parameters of the planetary ball mill include a ball-to-material ratio of 10:1, a ball milling time of 20 h, and a ball milling speed of 400 rpm.

[0130] After ball milling, the obtained metal premixed powder was screened for use, and the mesh size of the screen was 200 mesh.

[0131] Test Example 1

[0132] The porous metal-based diamond tools prepared in Examples 1-4 and Comparative Examples 1-3 were detected, and the detection methods were as follows: a laser particle size analyzer was used to detect the particle size of the ball-milled powder; the Archimedes drainage method was used to measure the porosity of each case; the ImageJ software was used to measure the pore size and pore density of each case; the Vickers hardness tester and the universal testing machine were used to detect the Vickers hardness value and the bending strength of each case, respectively. The results are shown in Table 1.

[0133] Table 1 Performance of porous metal-based diamond tools

[0134]

[0135] From Table 1, it can be seen that the porous metal-based diamond tools prepared by the method provided by the embodiments of the present application can achieve the comprehensive performance of high porosity (16-30%), small pore size (≤5 μm) and high bending strength (216 MPa when the porosity is 30%). Each of the performances is better than that of Comparative Example 1, which is due to the excessively large pore size (about 22 μm) in Comparative Example 1, so that the strength is still lower than that of Example 1 when the porosity is 30%. Comparative Example 2 changes the adding order of tin compared with the embodiments. Since tin does not participate in the ball milling process, it cannot well wrap the titanium hydride particles, and only relies on the particle rearrangement effect of liquid tin in the low-temperature and high-pressure sintering stage, which is not enough to effectively wrap the titanium hydride, thereby leading to poor pore-forming effect of the titanium hydride in the high-temperature and low-pressure sintering process. The inventors found that, in the ball milling steps of Example 1 and Comparative Example 2, the residual amount of titanium hydride and the participation of tin have a greater relationship under the same ball milling parameters. Since there is participation of tin in the ball milling process, the residual amount of titanium hydride in Example 1 is higher than that in Comparative Example 2, so that the porosities of the porous metal-based diamond tools provided by Comparative Examples 2-4 are all worse than that of the scheme of the embodiments of the present application. Comparative Example 3 is only different from Examples 1-4 in that the content of titanium hydride is increased (from 2.5 wt% to 12 wt%). The increase of the content of titanium hydride does not increase the porosity. On the contrary, due to the increase of the titanium content, more titanium-rich hard and brittle phases are easily generated in the matrix, so that the strength obtained under the conditions of similar porosity and pore size to Example 2 is lower. The difference between Comparative Example 4 and Example 1 is only that the ball milling speed is increased, and the data shows that excessively high speed can lead to decomposition of titanium hydride, so that the pore-forming effect is decreased by 59% (from 29% porosity to 12% porosity) when the mass ratio of titanium hydride is 5.

[0136] The preferred embodiments of the present application have been described above with reference to the drawings, but the present application is not limited to the above examples, and various modifications and changes can be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A porous metal-based diamond tool, characterized by, The porous metal-based diamond tool comprises a base with a porous structure, and a solid region in the base comprises metal and diamond, wherein the volume ratio of the diamond to the metal is 10-30:70-90; The metal comprises copper, a low-melting-point metal, and titanium hydride, and the mass ratio of the copper, the low-melting-point metal, and the titanium hydride is 75-85:10-20:2.5-10; wherein the low-melting-point metal is tin; The porous structure comprises titanium pores generated by thermal decomposition of the titanium hydride, and the titanium pores are wrapped by the low-melting-point metal, and the melting point of the low-melting-point metal is ≤500℃; The preparation method of the porous metal-based diamond tool comprises mixing the copper, the low-melting-point metal, and the titanium hydride in a proportion by ball milling to obtain a metal premixed powder, then sintering and shaping the composite powder obtained by mixing the metal premixed powder and diamond at low temperature and high pressure, and then performing high-temperature and low-pressure heat treatment. The sintering and shaping at low temperature and high pressure comprises placing the composite powder in a mold and sintering in a vacuum or inert atmosphere; and the parameters of the sintering at low temperature and high pressure comprise a sintering temperature of 300-400℃, a sintering pressure of 25-35MPa, a temperature rising rate of 80-120℃ / min, and a pressure maintaining time of 10-20min. The parameters of the high-temperature and low-pressure heat treatment comprise a heat treatment temperature of 600-850℃, a heat preservation time of 20-40min, a heat treatment pressure of 0-5MPa, and a heat treatment environment of a vacuum or inert atmosphere.

2. The porous metal-matrix diamond tool of claim 1, wherein, The parameters of the ball milling comprise a ball-to-material ratio of 5-10:1, a ball milling time of 10-20h, and a ball milling rotating speed of 80-300rpm.

3. The porous metal-based diamond tool according to claim 1 or 2, characterized in that, After the ball milling, the metal premixed powder is sieved through a sieve with a mesh size of ≥200mesh.

4. The porous metal-matrix diamond tool of claim 1, wherein, The mixing of the metal premixed powder and the diamond comprises uniformly mixing in a mixer.

5. The porous metal-matrix diamond tool of claim 4, wherein, The rotating speed of the mixer is 40-80rpm, and the mixing time is 1-3h.

6. Use of the porous metal-based diamond tool according to any one of claims 1-5 in a porous metal material.

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