An advanced diamond composite material for cutting articles and a method of making the same

Abstract

The present application relates to the technical field of ceramic composite material, in particular to an advanced diamond composite material for cutting products and a preparation method thereof, which comprises the following steps: weighing raw materials; mixing to obtain a composite powder; pressing the dried composite powder into a preform; transferring to a hot-pressing sintering furnace for sintering; cooling to room temperature with the furnace, and then processing the material blank into a final shape of the required cutting product. In the present application, the low-temperature densification advantage of the glass phase, the interface strengthening advantage of the active ceramic phase, the toughening advantage of the nanoparticles and the thermal matching advantage of the minerals are organically combined to prepare an advanced diamond composite material with high strength, high toughness, high interface bonding force and excellent thermal stability, which is suitable for manufacturing high-performance and long-life cutting tools.

Description

Technical Field

[0001] This invention relates to the field of ceramic composite materials technology, and more specifically, to an advanced diamond composite material for cutting products and its preparation method. Background Technology

[0002] Diamond-ceramic composites are key materials that use diamond as the hard phase and inorganic non-metallic ceramic or glassy phases as binders. Due to the high hardness of diamond and the excellent thermal stability and chemical inertness of the ceramic phase, they are considered a promising development direction in the field of superhard tools. However, limited by the inherent brittleness of the ceramic binder phase, the macroscopic mechanical strength, especially fracture toughness, of these composites is generally insufficient. Under high mechanical impact loads, they are prone to catastrophic brittle fracture, which severely restricts their application in high-efficiency, heavy-duty cutting conditions.

[0003] In existing technologies, the binder phase of such materials often employs a single oxide ceramic (such as α-alumina or crystalline silica) or a specific silicate glass system. These binder phases differ significantly from diamond particles in physical and chemical properties, resulting in poor interfacial compatibility. The bonding primarily relies on mechanical interlocking and weak van der Waals forces, leading to weak interfacial adhesion. During actual cutting, under alternating loads, the interface easily becomes a crack initiation point, causing premature detachment of diamond particles. Simultaneously, the high brittleness of the binder phase itself results in poor overall impact resistance of the composite material. Microcracks during dynamic machining can easily propagate rapidly along grain boundaries or through the glass phase, leading to tool chipping or overall failure.

[0004] On the other hand, there is usually a significant mismatch in the coefficient of thermal expansion between the selected ceramic or glass binder phase and the diamond. During the cooling stage after material preparation or the cyclical temperature rise during actual processing, the resulting internal stress is difficult to release effectively, leading to the formation of a microcrack network at the interface and within the matrix, significantly reducing the material's effective load-bearing area and strength. Furthermore, traditional pressureless sintering processes cannot achieve complete densification of the ceramic matrix; the remaining porosity not only weakens the matrix's mechanical holding force to the diamond but also provides pathways for stress corrosion and fatigue crack initiation and propagation, ultimately resulting in a sharp reduction in the lifespan of cut products under complex loads. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of poor overall mechanical properties, poor diamond particle retention, and short tool service life in existing diamond composite materials with ceramic or glass as the binder phase, which are caused by weak interfacial bonding between the two phases, high intrinsic brittleness of the ceramic matrix, thermal stress concentration due to thermal expansion mismatch between components, and insufficient sintering densification.

[0006] The purpose of this invention is to provide an advanced diamond composite material for cutting products and its preparation method. By using glass phase viscous flow sintering and multiphase interface modification technology, the matrix has a high degree of densification and the chemical holding and mechanical encapsulation of diamond particles are significantly enhanced. The composite material as a whole exhibits high toughness, high strength and excellent thermal matching, which completely overcomes the performance defects of traditional ceramic-based diamond tools.

[0007] To achieve the above objectives, one objective of this invention is to provide an advanced diamond composite material for cutting products, comprising the following raw materials in the following mass percentages:

[0008] Chromite powder 4-8%, borosilicate glass powder 15-25%, carbide powder 8-18%, nano-zirconia 1-3%, balance diamond abrasive grains.

[0009] As a further improvement to this technical solution, the carbide powder includes silicon carbide powder and titanium carbide powder, and the mass ratio of silicon carbide powder to titanium carbide powder is 5:3.

[0010] A second objective of this invention is to provide a method for preparing the aforementioned advanced diamond composite material for cutting products, comprising the following steps:

[0011] Step S1: Weigh the raw materials according to the mass ratio;

[0012] Borosilicate glass powder, carbide powder, chromite powder and nano-zirconia are dry-mixed until a composite binder phase powder is obtained;

[0013] Step S2: The composite binder phase powder and diamond abrasive grains are put into a three-dimensional mixer for mixing to obtain composite powder;

[0014] The composite powder was removed from the mixer and vacuum dried at 80°C.

[0015] Subsequently, the dried composite powder is loaded into a pre-designed graphite mold and pressed into a preform.

[0016] Step S3: Transfer the graphite mold containing the preform to the hot press sintering furnace. First, evacuate the sintering furnace cavity.

[0017] Then, the temperature is increased to 600℃ at a rate of 10-15℃ / min, and held at this temperature for 30 min;

[0018] Subsequently, the temperature was increased to 850-950℃ at a rate of 5-10℃ / min, and when the temperature reached 800℃, axial pressure was applied simultaneously and maintained at the same temperature and pressure.

[0019] Step S4: After sintering, the material blank is cooled to room temperature in the furnace, the sintered material blank is taken out, and then the material blank is processed into the final shape of the required cut product.

[0020] As a further improvement to this technical solution, in step S1, borosilicate glass powder, carbide powder, chromite powder and nano-zirconia are placed together in a three-dimensional mixer and dry-mixed for 4-6 hours to obtain composite binder phase powder.

[0021] As a further improvement to this technical solution, in step S2, the mixing time is controlled at 6-8 hours.

[0022] As a further improvement to this technical solution, in step S2, the composite powder is pre-pressed at room temperature using a cold pressing process, with the pressure controlled at 20-50 MPa, to form a preform.

[0023] As a further improvement to this technical solution, in step S3, the sintering furnace cavity is evacuated to below 10⁻² Pa, and then filled with high-purity argon as a protective atmosphere.

[0024] As a further improvement to this technical solution, in step S3, the axial pressure is increased to 25-35 MPa.

[0025] As a further improvement to this technical solution, in step S3, the heat preservation and pressure holding time is 30-90 minutes.

[0026] As a further improvement to this technical solution, in step S4, after the furnace cools to room temperature, the pressure is first released, and the protective atmosphere is turned off after the temperature drops below 300°C. Finally, the sintered material billet is taken out.

[0027] This invention organically combines the advantages of low-temperature densification of the glass phase, the interface strengthening advantages of the active ceramic phase, the toughening advantages of nanoparticles, and the thermal matching advantages of minerals to prepare an advanced diamond composite material with high strength, high toughness, high interfacial bonding force, and excellent thermal stability, which is suitable for manufacturing high-performance, long-life cutting tools.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] In this advanced diamond composite material for cutting products and its preparation method, an inorganic composite material system is constructed with borosilicate glass powder as the core binder and multiple functional ceramic phases working synergistically. This system utilizes silicon carbide powder to construct a rigid skeleton to improve the wear resistance of the matrix, and uses titanium carbide powder to react with the diamond surface to generate a strong and tough TiC chemical bond layer, which significantly enhances the interfacial bonding force. At the same time, chromite powder is introduced as a thermal expansion regulator to effectively buffer the internal stress caused by thermal mismatch, and the phase transformation toughening effect of nano-zirconia is used to significantly improve the fracture toughness of the composite material, forming a multi-dimensional synergistic reinforcement mechanism.

[0030] In the preparation process, an optimized powder pretreatment and step-by-step hot pressing sintering process are adopted to first achieve uniform premixing of each component and full encapsulation of diamond particles. Then, the viscous flow densification of the glass phase and the interfacial reaction process are completed simultaneously. The traditional mechanical bonding is upgraded to a multi-component bonding mechanism that combines chemical bonding and mechanical encapsulation, and an advanced diamond composite material with high toughness, high strength and excellent thermal stability is successfully prepared. Attached Figure Description

[0031] Figure 1 This is a flowchart illustrating the preparation process of the present invention;

[0032] Figure 2 This diagram illustrates the coefficient of thermal expansion of the composite material when the mass percentage of chromite powder is different. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] One objective of this invention is to provide an advanced diamond composite material for cutting products, comprising the following raw materials in the following mass percentages:

[0035] Chromite powder 4-8%, borosilicate glass powder 15-25%, carbide powder 8-18%, nano-zirconia 1-3%, balance diamond abrasive grains.

[0036] The carbide powder includes silicon carbide powder and titanium carbide powder, and the mass ratio of silicon carbide powder to titanium carbide powder is 5:3.

[0037] In this invention, diamond abrasive grains serve as the core hard phase of the composite material, providing ultra-high hardness, wear resistance, and cutting ability. Borosilicate glass powder acts as a glass phase binder, melting and flowing during sintering to achieve low-temperature densification of the matrix. Chromite powder, as a multifunctional modifier, has a thermal expansion coefficient between that of diamond and glass, effectively buffering thermal stress; the chromium element also participates in interfacial reactions, further strengthening the bond. Nano-zirconia, as a toughening phase, utilizes its phase transformation toughening effect (tetragonal to monoclinic phase transformation) to effectively absorb energy, prevent crack propagation, and significantly improve the impact resistance of the composite material. Silicon carbide powder, in the carbide powder, acts as a wear-resistant reinforcing phase, improving the hardness and wear resistance of the matrix itself; its particles can improve the toughness of the material through crack deflection and bridging mechanisms, while titanium carbide powder, as an active interfacial modifier, reacts with the diamond surface during sintering to generate a strong TiC chemical bond layer, greatly enhancing the matrix's holding power over the diamond.

[0038] Please see Figure 1 As shown, a second objective of this invention is to provide a method for preparing the aforementioned advanced diamond composite material for cutting products, comprising the following steps:

[0039] Step S1: Weigh the raw materials according to the mass ratio.

[0040] Borosilicate glass powder, carbide powder, chromite powder, and nano-zirconia are placed together in a three-dimensional mixer and dry-mixed for 4-6 hours to obtain a highly uniform composite binder phase powder. This step is fundamental to achieving multiphase synergistic effects.

[0041] Step S2: Place the composite binder powder and the weighed diamond abrasive grains into a three-dimensional mixer for mixing. The mixing time is controlled at 6-8 hours to ensure that each diamond abrasive grain is fully coated and isolated by the composite binder powder, so as to achieve uniform distribution at the microscale and obtain composite powder. To avoid segregation during the mixing process, a small amount (e.g., 1%-2% anhydrous ethanol) can be added as a dispersion medium for wet mixing.

[0042] The uniformly mixed composite powder is removed from the mixer and vacuum dried at 80°C to completely remove the solvent.

[0043] Subsequently, the dried composite powder is loaded into a designed graphite mold, and at room temperature, the composite powder is pre-pressed using a cold pressing process, with the pressure controlled at 20-50 MPa, to form a preform with a certain strength.

[0044] Step S3: Transfer the graphite mold containing the preform to the hot press sintering furnace. First, evacuate the sintering furnace cavity to below 10-2 Pa. Then, fill it with high-purity argon as a protective atmosphere to prevent the diamond from graphitizing at high temperature and the oxidation of the components.

[0045] Then, the temperature is increased to 600℃ at a rate of 10-15℃ / min and held at this temperature for 30 minutes to completely remove any adsorbed gases and stress that may remain in the billet.

[0046] Subsequently, the temperature is increased at a rate of 5-10℃ / min to the final sintering window: 850-950℃. When the temperature reaches 800℃, axial pressure is simultaneously applied, slowly increasing to 25-35 MPa, and held at this temperature and pressure for 30-90 min. This stage is the critical period for glass phase viscous flow sintering and multiphase interface modification.

[0047] Borosilicate glass powder softens and melts, producing a viscous flow that, under pressure, fully fills all the gaps between particles, achieving extremely high density (relative density > 97%) in the matrix.

[0048] Under high temperature and an active atmosphere, titanium carbide (TiC) reacts with the diamond surface to form a robust TiC chemical bond layer. Simultaneously, the active components in chromite also participate in the interfacial reaction, collectively forming a strong "ceramic" interfacial bridge, greatly enhancing the matrix's chemical retention of the diamond. The molten glass phase exerts a powerful mechanical encapsulation effect on the diamond and various ceramic particles.

[0049] Nano-zirconia is uniformly dispersed in the matrix, playing a role in phase transformation toughening; chromite, as a functional filler, effectively buffers the thermal stress concentration caused by the difference in thermal expansion coefficient.

[0050] Step S4: After sintering, the furnace is cooled to room temperature. After cooling to room temperature, the pressure is first released, and the protective atmosphere is closed after the temperature drops below 300°C. Finally, the sintered high-density composite material blank is taken out and then processed into the required cutting products (such as saw blade teeth, grinding blocks, etc.) by wire cutting, laser processing or diamond wheel grinding.

[0051] The following specific embodiments further illustrate the advanced diamond composite material for cutting products and its preparation method provided by the present invention.

[0052] Example 1

[0053] Step S1: Weigh out 4% chromite powder, 25% borosilicate glass powder, 8% carbide powder, and 3% nano-zirconia according to the mass ratio, with the remainder being diamond abrasive grains. The carbide powder includes silicon carbide powder and titanium carbide powder, with a mass ratio of silicon carbide powder to titanium carbide powder of 5:3.

[0054] Borosilicate glass powder, carbide powder, chromite powder and nano-zirconia were placed together in a three-dimensional mixer and dry-mixed for 4 hours to obtain composite binder phase powder.

[0055] Step S2: The composite binder powder and diamond abrasive particles are put into a three-dimensional mixer for mixing. The mixing time is controlled at 8 hours to obtain composite powder.

[0056] The composite powder was removed from the mixer and vacuum dried at 80°C.

[0057] Subsequently, the dried composite powder is loaded into a pre-designed graphite mold and pre-pressed at room temperature using a cold pressing process, with the pressure controlled at 20 MPa, to form a preform.

[0058] Step S3: Transfer the graphite mold containing the preform to the hot press sintering furnace. First, evacuate the sintering furnace cavity to below 10-2 Pa. Then, fill it with high-purity argon as a protective atmosphere.

[0059] Then, the temperature is increased to 600℃ at a rate of 15℃ / min and held at this temperature for 30min.

[0060] Subsequently, the temperature was increased to 950℃ at a rate of 5℃ / min, and when the temperature reached 800℃, axial pressure was applied synchronously, increasing to 25MPa, and the temperature and pressure were maintained for 90min.

[0061] Step S4: After sintering, the furnace is cooled to room temperature. After the furnace is cooled to room temperature, the pressure is first released. After the temperature drops below 300°C, the protective atmosphere is turned off. Finally, the sintered material blank is taken out and processed into the final shape of the cut product.

[0062] Example 2

[0063] Step S1: Weigh out 6% chromite powder, 20% borosilicate glass powder, 12% carbide powder, and 2% nano-zirconia according to the mass ratio, with the remainder being diamond abrasive grains. The carbide powder includes silicon carbide powder and titanium carbide powder, with a mass ratio of silicon carbide powder to titanium carbide powder of 5:3.

[0064] Borosilicate glass powder, carbide powder, chromite powder and nano-zirconia were placed together in a three-dimensional mixer and dry-mixed for 5 hours to obtain composite binder phase powder.

[0065] Step S2: The composite binder powder and diamond abrasive grains are put into a three-dimensional mixer for mixing. The mixing time is controlled at 7 hours to obtain composite powder.

[0066] The composite powder was removed from the mixer and vacuum dried at 80°C.

[0067] Subsequently, the dried composite powder is loaded into a pre-designed graphite mold and pre-pressed at room temperature using a cold pressing process, with the pressure controlled at 40 MPa, to form a preform.

[0068] Step S3: Transfer the graphite mold containing the preform to the hot press sintering furnace. First, evacuate the sintering furnace cavity to below 10-2 Pa. Then, fill it with high-purity argon as a protective atmosphere.

[0069] Then, the temperature is increased to 600℃ at a rate of 15℃ / min and held at this temperature for 30min.

[0070] Subsequently, the temperature was increased to 900℃ at a rate of 8℃ / min, and when the temperature reached 800℃, axial pressure was applied synchronously, increasing to 30MPa, and the temperature and pressure were maintained for 60min.

[0071] Step S4: After sintering, the furnace is cooled to room temperature. After the furnace is cooled to room temperature, the pressure is first released. After the temperature drops below 300°C, the protective atmosphere is turned off. Finally, the sintered material blank is taken out and processed into the final shape of the cut product.

[0072] Example 3

[0073] Step S1: Weigh out 8% chromite powder, 15% borosilicate glass powder, 18% carbide powder, and 1% nano-zirconia according to the mass ratio, with the remainder being diamond abrasive grains. The carbide powder includes silicon carbide powder and titanium carbide powder, with a mass ratio of silicon carbide powder to titanium carbide powder of 5:3.

[0074] Borosilicate glass powder, carbide powder, chromite powder and nano-zirconia were placed together in a three-dimensional mixer and dry-mixed for 6 hours to obtain composite binder phase powder.

[0075] Step S2: The composite binder powder and diamond abrasive grains are put into a three-dimensional mixer for mixing. The mixing time is controlled at 6 hours to obtain composite powder.

[0076] The composite powder was removed from the mixer and vacuum dried at 80°C.

[0077] Subsequently, the dried composite powder is loaded into a pre-designed graphite mold and pre-pressed at room temperature using a cold pressing process, with the pressure controlled at 50 MPa, to form a preform.

[0078] Step S3: Transfer the graphite mold containing the preform to the hot press sintering furnace. First, evacuate the sintering furnace cavity to below 10-2 Pa. Then, fill it with high-purity argon as a protective atmosphere.

[0079] Then, the temperature is increased to 600℃ at a rate of 10℃ / min and held at this temperature for 30min.

[0080] Subsequently, the temperature was increased to 850℃ at a rate of 10℃ / min, and when the temperature reached 800℃, axial pressure was applied synchronously, increasing to 35MPa, and the temperature and pressure were maintained for 30min.

[0081] Step S4: After sintering, the furnace is cooled to room temperature. After the furnace is cooled to room temperature, the pressure is first released. After the temperature drops below 300°C, the protective atmosphere is turned off. Finally, the sintered material blank is taken out and processed into the final shape of the cut product.

[0082] The cut articles prepared in Examples 1-3 were tested as follows.

[0083] Bulk density test: Referring to ASTM B962 standard, the composite material was cut into regular or irregular block specimens. The test was conducted using a precision balance and an Archimedes' displacement device. The dry mass of the specimen in air, the wet weight in air after saturation, and the suspended weight in water were recorded. The bulk density was calculated as (dry mass / (wet weight - suspended weight) × water density), and the results were recorded in Table 1.

[0084] Flexural strength test: Referring to ISO 14704 standard, the composite material was cut and ground into strips of 3mm × 4mm × 40mm. A three-point bending test was performed at room temperature using a universal testing machine with a span of 30mm and a loading speed of 0.5mm / min. The maximum load borne by the specimen before fracture was recorded, and the flexural strength was calculated as (3 × maximum load × span / (2 × specimen width × specimen thickness²)). The results are recorded in Table 1.

[0085] Thermal expansion coefficient test: Referring to ASTM E228 standard, the composite material was processed into cylindrical specimens with a diameter of φ6mm × 25mm. Using a thermal expansion apparatus under argon protection, the specimens were heated from room temperature to 600℃ at a heating rate of 5℃ / min. The change in specimen length with temperature was recorded, and the average thermal expansion coefficient (length change / original length / temperature difference) was calculated in the temperature range of 25-600℃. The results are recorded in Table 1.

[0086] Table 1 Summary of the performance of the cut products from Examples 1-3

[0087]

[0088] As shown in Table 1, the bulk density of the cut products obtained in Examples 1-3 is greater than 3.8 g / cm³. 3 The flexural strength is not less than 610 MPa, and the coefficient of thermal expansion is not higher than 4.9 × 10⁻⁶. -6 / ℃ indicates that the present invention can prepare diamond ceramic composite materials with high sintering densification, high macroscopic flexural strength and low coefficient of thermal expansion.

[0089] In this invention, borosilicate glass powder is first used as the core binder to construct the matrix, achieving efficient densification during sintering through its unique low-temperature viscous flow characteristics. A composite reinforcement system is constructed by introducing silicon carbide powder and titanium carbide powder. Silicon carbide powder forms a rigid skeleton to improve the wear resistance and hardness of the matrix, while its particles improve the material's toughness through crack deflection and bridging mechanisms. Titanium carbide powder, as a key active phase, undergoes an interfacial reaction with the diamond surface during sintering to generate a strong and tough TiC chemically bonded layer. Chromite powder is introduced as a thermal expansion regulator, with a thermal expansion coefficient between that of diamond and the glass phase, effectively buffering internal stress caused by thermal mismatch. Simultaneously, its active components participate in the interfacial reaction, strengthening the bonding strength. Crucially, nano-zirconia, through its phase transformation toughening effect, undergoes a martensitic phase transformation under stress, absorbing crack propagation energy and significantly improving the fracture toughness of the composite material.

[0090] Furthermore, component homogenization is achieved through optimized powder pretreatment and mixing processes: First, the glass phase is premixed with various functional ceramic powders to form a highly homogeneous composite binder phase. Then, a precisely controlled mixing process ensures that the composite binder phase fully encapsulates the diamond particles, laying the foundation for subsequent interfacial reactions. In the hot-pressing sintering stage, a synergistic process of stepped heating and simultaneous pressurization is adopted. Under a protective atmosphere, volatile substances in the system are first eliminated. Then, within a specific sintering window, the viscous flow of the glass phase and the interfacial reaction are carried out simultaneously. The molten glass phase completes the dense encapsulation of hard particles under pressure, while the active components diffuse and react at the diamond interface, forming a strong "ceramic" interfacial bridge.

[0091] This process elevates the traditional mechanical bonding to a multi-faceted bonding mechanism that primarily relies on chemical bonding and secondarily on mechanical encapsulation. This completely resolves the performance defects of composite materials caused by weak interfacial bonding, high matrix brittleness, concentrated thermal stress, and insufficient densification, ultimately resulting in advanced diamond cutting products with high toughness, high strength, excellent thermal compatibility, and long-term service stability.

[0092] Test case

[0093] In the formulation of this invention, chromite powder serves as a key multifunctional modifier, significantly enhancing the performance of composite materials through synergistic physical and chemical effects. The active elements such as chromium and iron released during sintering can react with the diamond surface to form a transition layer of carbides such as Cr3C2, which, in conjunction with titanium carbide, strengthens the interfacial chemical bonding, effectively addressing the core issue of weak adhesion. Simultaneously, its coefficient of thermal expansion, falling between that of diamond and the glass phase, acts as an ideal thermal expansion gradient buffer layer, significantly reducing residual stress caused by thermal mismatch between components and inhibiting the initiation of microcracks. Furthermore, the high hardness and high melting point of chromite powder itself provide a high-temperature reinforcing skeleton for the glass matrix, improving overall wear resistance and high-temperature stability.

[0094] To verify that chromite powder is a key component in the formulation of this invention, enabling it to provide diamond ceramic composite materials with high sintering densification, high macroscopic flexural strength, and low coefficient of thermal expansion, this experimental example differs from Example 1 above by only changing the composition, either by omitting chromite powder or replacing it with alumina. The prepared cut products were then tested using the performance testing methods provided in the above examples, and the results are recorded in Table 2.

[0095] Table 2 Performance Comparison of Cut Products

[0096]

[0097] As shown in Table 2, compared with Example 1, if chromite powder is missing, or if chromite powder is replaced with alumina, which has a lower coefficient of thermal expansion, the interfacial reaction activity between alumina and diamond will be much lower than that of chromite, and the matching of its coefficient of thermal expansion with diamond will be less than that of chromite. This will lead to a significant decrease in interfacial bonding strength and thermal shock resistance. The replaced material is more prone to debonding at the interface, and under repeated thermal cycling, it will be accelerated to break down due to stress concentration. It cannot achieve the comprehensive performance improvement brought by chromite, and ultimately affects the service life of the cut products under harsh working conditions.

[0098] Furthermore, in the formulation of this invention, the mass percentage of chromite powder in the composition is controlled at 4-8%. Deviations from this range will lead to a significant decrease in the performance of the composite material. When the chromite powder content is too low, an effective gradient transition layer of thermal expansion coefficient cannot be formed between the diamond and the glass phase. The residual stress generated during the sintering and cooling process due to thermal mismatch between components is difficult to release effectively, easily inducing microcracks in the interface region. Simultaneously, insufficient active components result in inadequate interfacial chemical reactions, failing to synergistically construct a complete "ceramic" interfacial bridge with titanium carbide. This leads to insufficient holding force of the matrix on the diamond, making it prone to early particle detachment under cutting loads, severely weakening the tool's cutting efficiency and service life.

[0099] When the chromite powder content is too high, the excessive spinel phase disrupts the continuity of the glass binder phase, hindering its viscous flow during sintering, leading to reduced matrix densification and increased porosity. Excessive chromite hard particles become internal stress concentration points, not only hindering the toughening effect of nano-zirconia but also promoting crack propagation and reducing the toughness of the composite material. Furthermore, excessive chromite content alters the overall wear mechanism of the matrix, transforming it from uniform wear to brittle wear dominated by hard phase spalling. This makes the tool edges prone to chipping during cutting, severely impacting machining accuracy and tool service stability.

[0100] To verify that the 4-8% mass proportion of chromite powder in the composite material is one of the key factors enabling this invention to provide diamond ceramic composite materials with high sintering densification, high macroscopic flexural strength, and low coefficient of thermal expansion, this experimental example, based on Example 1 above, only changes the mass proportion of chromite powder, setting it to 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%. Cutting products are then prepared, and the coefficient of thermal expansion of the cutting products is tested according to the method provided in the above examples. The results are as follows. Figure 2 As shown.

[0101] according to Figure 2 It can be seen that when the mass percentage of chromite powder in the composite material is 1%, 2%, 3%, 9% or 10%, which is not 4-8%, the coefficient of thermal expansion of the composite material is significantly greater than that when the mass percentage of chromite powder in the composite material is 4%, 5%, 6%, 7% or 8%.

[0102] Therefore, it can be shown that the 4-8% mass proportion of chromite powder in the composite material is one of the important factors that enable the present invention to provide diamond ceramic composite materials with high sintering densification, high macroscopic flexural strength and low coefficient of thermal expansion.

[0103] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an advanced diamond composite material for cutting products, characterized in that, Includes the following steps: Step S1: Weigh out 4-8% chromite powder, 15-25% borosilicate glass powder, 8-18% carbide powder, and 1-3% nano-zirconia according to the mass ratio, with the remainder being diamond abrasive grains. Borosilicate glass powder, carbide powder, chromite powder and nano-zirconia are dry-mixed until a composite binder phase powder is obtained; Step S2: The composite binder phase powder and diamond abrasive grains are put into a three-dimensional mixer for mixing to obtain composite powder; The composite powder was removed from the mixer and vacuum dried at 80°C. Subsequently, the dried composite powder is loaded into a pre-designed graphite mold and pressed into a preform. Step S3: Transfer the graphite mold containing the preform to the hot press sintering furnace. First, evacuate the sintering furnace cavity, then heat it to 600℃ at a rate of 10-15℃ / min, and hold it at this temperature for 30 minutes. Subsequently, the temperature was increased to 850-950℃ at a rate of 5-10℃ / min, and when the temperature reached 800℃, axial pressure was applied simultaneously and maintained at the same temperature and pressure. Step S4: After sintering, the material blank is cooled to room temperature in the furnace, the sintered material blank is taken out, and then the material blank is processed into the final shape of the required cut product; In step S1, the carbide powder includes silicon carbide powder and titanium carbide powder, and the mass ratio of silicon carbide powder to titanium carbide powder is 5:

3. In step S1, borosilicate glass powder, carbide powder, chromite powder and nano-zirconia are placed together in a three-dimensional mixer and dry-mixed for 4-6 hours to obtain composite binder phase powder.

2. The method for preparing the advanced diamond composite material for cutting products according to claim 1, characterized in that: In step S2, the mixing time is controlled at 6-8 hours.

3. The method for preparing the advanced diamond composite material for cutting products according to claim 1, characterized in that: In step S2, the composite powder is pre-pressed at room temperature using a cold pressing process, with the pressure controlled at 20-50 MPa, to form a preform.

4. The method for preparing the advanced diamond composite material for cutting products according to claim 1, characterized in that: In step S3, the sintering furnace cavity is evacuated to 10... -2 The pressure is below Pa, and then high-purity argon is introduced as a protective atmosphere.

5. The method for preparing the advanced diamond composite material for cutting products according to claim 1, characterized in that: In step S3, the axial pressure is increased to 25-35 MPa.

6. The method for preparing the advanced diamond composite material for cutting products according to claim 1, characterized in that: In step S3, the heat preservation and pressure holding time is 30-90 minutes.

7. The method for preparing the advanced diamond composite material for cutting products according to claim 1, characterized in that: In step S4, after the furnace cools to room temperature, the pressure is first released, and the protective atmosphere is turned off after the temperature drops below 300°C. Finally, the sintered material billet is taken out.

8. An advanced diamond composite material for cutting products prepared by the preparation method according to any one of claims 1-7, characterized in that, Including the following raw materials: Chromite powder, borosilicate glass powder, carbide powder, nano-zirconia, and diamond abrasive grains, wherein: The diamond abrasive grains serve as the core hard phase of the composite material; the borosilicate glass powder acts as a glass phase binder, achieving low-temperature densification of the matrix through viscous flow during sintering; the carbide powder includes silicon carbide powder and titanium carbide powder, wherein silicon carbide powder serves as a wear-resistant reinforcing phase, forming a rigid skeleton in the matrix to improve overall hardness and wear resistance, and titanium carbide powder serves as an active interface modifier, reacting with the diamond surface during sintering to generate a TiC chemical bond layer, enhancing the interfacial bonding strength; The chromite powder, as a multifunctional modifier, has a thermal expansion coefficient between that of diamond and glass, effectively buffering the thermal stress concentration caused by thermal mismatch. At the same time, the active components participate in the interfacial reaction, further strengthening the bonding interface. The nano-zirconia, as a toughening phase, absorbs crack propagation energy through stress-induced phase transformation toughening effect, improving the fracture toughness and impact resistance of the composite material. The components work synergistically to form a diamond composite material with high strength, high toughness and excellent thermal stability.

Images