Superhard wear-resistant diamond roller and preparation method thereof

Abstract

This invention relates to the field of diamond and discloses an ultrahard, wear-resistant diamond roller and its preparation method. The diamond roller prepared by this invention possesses excellent comprehensive mechanical properties and service performance. Its internal structure is dense and wear-resistant, exhibiting outstanding impact resistance and fracture resistance reliability, achieving an ultra-long service life under high-load conditions. A high-strength and tough load-bearing skeleton is constructed using rhenium-containing tungsten-based pre-alloy powder; a robust carbide metallurgical interface is formed by in-situ reaction of active titanium metal on the diamond surface; nano-diamonds are introduced for micro-filling and dispersion reinforcement; and an optimized spark plasma sintering process is combined to ensure densification while maximizing the preservation of material properties.

Description

Technical Field

[0001] This invention relates to the field of diamond, and more specifically, to an ultra-hard wear-resistant diamond roller and its preparation method. Background Technology

[0002] Diamond rollers are high-precision superhard tools primarily used for dressing other abrasives (especially ceramic-bonded or resin-bonded grinding wheels). In modern precision manufacturing, such as automotive engines, bearings, and aerospace, the final geometric accuracy and surface quality of key components largely depend on the performance of the grinding wheels used in the grinding process. The performance of these grinding wheels, in turn, directly depends on the precision and stability of the diamond rollers used to dress their contours. As the mother machine in the entire precision machining chain, the performance of the diamond roller is crucial.

[0003] However, in actual high-speed, high-load dressing operations, existing diamond rollers generally face a prominent problem: their service life and performance stability are insufficient to meet increasingly stringent industrial demands. After a period of service, the working surface of the roller prematurely exhibits decreased precision, accelerated wear, and even localized chipping. This not only leads to frequent replacement of expensive rollers, increasing production costs and downtime, but also directly affects the machining accuracy of the dressed grinding wheel, thereby reducing the final product's pass rate and consistency. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides an ultra-hard wear-resistant diamond roller and its preparation method, solving the common technical problems faced in the field of existing diamond rollers.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: This invention provides an ultrahard wear-resistant diamond roller and a method for preparing the same, comprising the following steps: S1. Titanium powder and large diamond particles are added to a high-energy ball mill at a mass ratio of 1:15~25. Under a protective atmosphere, the titanium powder is coated on the surface of the diamond particles to form surface-modified large diamond particles. S2, by weight, 110-130 parts of the surface-modified large-particle diamond, 90-110 parts of tungsten-rhenium pre-alloy powder with a rhenium content of 5-9%, and 6-12 parts of nano-diamond are added to a three-dimensional motion mixer and mixed under a protective atmosphere to prepare a composite powder. S3 The composite powder is loaded into a graphite mold, compacted, and then placed into a spark plasma sintering furnace. Vacuum is drawn and pre-pressed, preheated and pressurized, and then heated to the sintering temperature at 30~50℃ / min and held for 6~10min. After the S4 sintering is completed and cooled, it is taken out and surface-processed to obtain the superhard wear-resistant diamond roller.

[0007] In a preferred embodiment of the method for preparing the superhard wear-resistant diamond roller of the present invention, in step S1, the mass ratio of the titanium powder to the large diamond particles is 1:20.

[0008] As a preferred embodiment of the method for preparing the superhard wear-resistant diamond roller of the present invention, in step S2, the surface-modified large-particle diamond is 120 parts, the tungsten-rhenium pre-alloy powder is 100 parts, and the amount of nano-diamond added is 8 parts.

[0009] In a preferred embodiment of the method for preparing the superhard wear-resistant diamond roller of the present invention, the rhenium content in the tungsten-rhenium pre-alloy powder is 7%.

[0010] In a preferred embodiment of the method for preparing the superhard wear-resistant diamond roller of the present invention, in step S3, the heating rate of the heating process is 40℃ / min, and the heat preservation process lasts for 8min.

[0011] As a preferred embodiment of the method for preparing superhard wear-resistant diamond rollers according to the present invention, the protective atmosphere is one or more of argon, nitrogen or high vacuum; in step S1, the mixing ball milling process of the high-energy ball mill is continuous ball milling at 200~400 prm for 2~6 hours.

[0012] As a preferred embodiment of the method for preparing superhard wear-resistant diamond rollers according to the present invention, in step S2, the operating parameters of the three-dimensional motion mixer are a rotation speed of 40~60 rpm and a mixing time of 6~8 h.

[0013] In a preferred embodiment of the method for preparing superhard wear-resistant diamond rollers according to the present invention, in step S3, the vacuum degree of the electro-plasma sintering furnace is below 5×10⁻³Pa, and a pre-pressure of 4~6MPa is applied to the material in the graphite mold; the target preheating temperature is 750~850℃, and the force applied to the material during this period is increased to 40~60MPa; the sintering temperature is 1200~1300℃.

[0014] As a preferred embodiment of the method for preparing the superhard wear-resistant diamond roller of the present invention, in step S4, the surface processing includes: using wire electrical discharge machining and laser processing to refine the outer contour, inner hole and working surface of the roller; and using fine polishing paste to polish the working surface of the roller.

[0015] The present invention also provides an ultra-hard wear-resistant diamond roller, which is prepared by the above method, wherein: the prepared ultra-hard wear-resistant diamond roller has a bonding interface layer composed of titanium carbide between the large diamond particles and the tungsten-rhenium metal matrix; and nanodiamonds are dispersed in the grain boundaries and within the grains of the tungsten-rhenium metal matrix.

[0016] The beneficial effects of this invention are as follows: the diamond roller obtained has good comprehensive mechanical properties and service performance, its internal structure is dense, its wear resistance and resistance to external loads are excellent, it has excellent impact resistance and crack propagation inhibition capabilities, which greatly improves its reliability under high load and dynamic working conditions, avoids brittle fracture, and its long service life gives it good economic benefits.

[0017] Using rhenium-containing tungsten-based pre-alloyed powder as the binder matrix, the brittleness of traditional tungsten matrices is addressed through the rhenium effect, providing a high-strength and tough load-bearing skeleton for the entire roller. Through the in-situ reaction of active titanium, a continuous TiC metallurgical bonding interface layer is formed between large diamond particles and the tungsten-rhenium matrix. Fixing the diamond onto the matrix solves the problem of premature abrasive detachment caused by insufficient interfacial bonding in traditional tools, significantly improving the grinding ratio. Nanodiamonds are dispersed throughout the grain boundaries and interiors of the tungsten-rhenium matrix, effectively filling micropores and providing significant dispersion strengthening and grain refinement, thus increasing the material's density and hardness. By adjusting the process parameters of spark plasma sintering, performance loss is minimized. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The figure shows the experimental results of optimizing the ratio of different diamonds.

[0020] Figure 2 The figure shows the experimental results of optimizing the amount of titanium powder added.

[0021] Figure 3 The figure shows the experimental results of optimizing the tungsten-rhenium pre-alloy ratio.

[0022] Figure 4 Figure 1 shows the experimental results of SPS process parameter optimization.

[0023] Figure 5 Figure 2 shows the experimental results of SPS process parameter optimization.

[0024] Figure 6This is a flowchart illustrating the preparation process of an ultra-hard, wear-resistant diamond roller. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "example" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention. The appearance of an embodiment in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that mutually excludes other embodiments.

[0028] Example 1 This embodiment aims to develop a superhard composite material system that combines hardness, wear resistance, and high interfacial bonding strength. It is intended to overcome the technical bottlenecks of traditional metal-bonded diamond tools under high-speed, heavy-load grinding conditions, such as premature abrasive detachment and shortened overall tool life due to the softening and rapid wear of the matrix material at high temperatures, and insufficient bonding between diamond abrasive grains and the matrix.

[0029] 1.1 Screening of toughening modified materials Conventional pure tungsten or tungsten-based binders are inherently brittle and prone to microcrack propagation under impact loads or thermal stress, leading to the fundamental defect of abnormal diamond abrasive grain spalling or tool matrix fragmentation. Therefore, it is necessary to screen for modified materials with crack deflection and energy absorption mechanisms.

[0030] The blank group used diamond and tungsten metal binder in a mass ratio of 50:50. The diamond was composed of large diamond particles with a particle size of 100-120 mesh and nanodiamonds with an average particle size of 50-100 nm.

[0031] Experimental groups (based on tungsten powder mass fraction): A1 with 5% rhenium (Re), A2 with 15% molybdenum (Mo), A3 with 2% iridium (Ir), A4 with 5% tantalum (Ta), A5 with 3% titanium carbide (TiC) powder, A6 with 2% hexagonal boron nitride (h-BN) powder, A7 with 1% yttrium oxide (Y2O3) powder, A8 with 5% silicon carbide whiskers (SiC-w), A9 with 1% carbon nanotubes (CNTs), A10 with 2% titanium (Ti) powder, A11 with 1.5% zirconium (Zr) powder, A12 with 0.5% yttrium (Y) powder, and A13 with 1% hafnium (Hf) powder.

[0032] The optimal addition amount of each toughening modifier was selected based on publicly available literature and known mature processes in the industry. All samples in all groups were prepared using the same mixing, molding, and sintering process.

[0033] The density of the sample was measured using the Archimedes' displacement method. A higher density value indicates lower porosity and a denser structure within the sample.

[0034] The hardness of the polished sample surface was measured using a Vickers hardness tester. A diamond pyramidal indenter was used, and a test force of 10 kgf (98 N) was applied for 15 seconds. After the load was removed, the lengths of the two diagonals of the indentation were measured under a microscope, and their average value was calculated. For diamond rollers, the hardness of the matrix directly affects its wear resistance and its ability to hold diamond abrasive grains. A sufficiently high hardness value is a fundamental prerequisite for ensuring a long tool life and high efficiency.

[0035] The sample was processed into a standard strip-shaped specimen measuring 3mm × 4mm × 36mm. The specimen was placed on two support rollers with a span of 30mm, and a constant loading rate of 0.5mm / min was applied at the mid-span of the specimen until fracture. The testing machine automatically recorded the maximum load (F_max) at fracture. Bending strength reflects a material's ability to resist fracture when subjected to bending stress. High bending strength indicates that the material not only has high strength but also few internal defects, a uniform structure, and the ability to withstand greater external loads.

[0036] Using a Vickers hardness tester, an indentation was made on the polished surface of the sample under a test force much greater than that used in hardness testing (30 kgf, or 294 N in this experiment). Under this load, clear radial cracks initiated at the four corners of the indentation. After unloading, the total length (c) from the center of the indentation to the tip of each crack was measured. Combining the measured Vickers hardness (HV) and the test force (P), the fracture toughness value was calculated using the corresponding empirical formula. Fracture toughness is a quantitative characterization of a material's ability to prevent crack propagation. A high fracture toughness value means that when microcracks exist within the material, more energy is required for the cracks to continue propagating, making the material less prone to sudden, catastrophic brittle fracture.

[0037] The test results are as follows: Among them, hexagonal boron nitride showed good modification of fracture toughness, but significantly reduced the Vickers hardness of the sample; silicon carbide effectively improved the Vickers hardness of the sample, but its fracture toughness was poor; carbon nanotubes significantly improved the flexural strength of the sample, but the sample density was low, indicating that it would produce microscopic defects. Rhenium showed good overall improvement in the performance of the sample, and was therefore chosen as a toughening modifier.

[0038] 1.2 Screening of interfacial bonding enhancers Diamond naturally does not wet most metal matrices and has poor chemical affinity, causing diamond abrasive grains to peel off from the matrix prematurely before reaching their lifespan due to insufficient interfacial bonding. This leads to tool failure. To address this, an interfacial active element needs to be introduced to induce an in-situ chemical reaction with the diamond surface during sintering, forming a strong and stable carbide metallurgical bonding layer. This results in a highly reliable and long-life diamond raw material.

[0039] Based on 100 samples of the substrate determined in Experiment 1.1, the following modifiers were added.

[0040] Experimental groups: B1 with 2.1 parts titanium (Ti), B2 with 2.9 parts zirconium (Zr), B3 with 3.1 parts hafnium (Hf), B4 with 1.8 parts vanadium (V), B5 with 2.7 parts niobium (Nb), B6 ​​with 1.6 parts chromium (Cr), B7 with 0.8 parts iron (Fe), B8 with 1.0 part cobalt (Co), B9 with 1.2 parts nickel (Ni), B10 with 1.4 parts manganese (Mn), B11 with 0.6 parts scandium (Sc), B12 with 0.8 parts yttrium (Y), B13 with 1.3 parts cerium (Ce), B14 with 1.9 parts aluminum (Al), and B15 with 2.4 parts silicon (Si).

[0041] In addition to evaluating the basic mechanical properties by testing bending strength and Vickers hardness, it is also necessary to process the samples in each group into grinding blocks of uniform specifications and install them on a precision surface grinder. Carbide (YG8) is selected as the standard workpiece to be processed and subjected to 1000 reciprocating grinding cycles. The mass of the dried grinding blocks and workpieces before and after grinding is measured, and the wear volume of the grinding block and the volume removed from the workpiece are calculated based on the density of their respective materials, thus calculating the grinding ratio. The grinding ratio quantifies the durability and economy of the grinding tool. A high G-value indicates that the grinding tool itself suffers less wear when grinding the same volume of workpiece. If the interfacial bonding force is insufficient, the diamond will prematurely detach under the impact and friction of the grinding force, leading to rapid wear of the grinding tool and a low G-value.

[0042] The test results are as follows: Chromium effectively improves Vickers hardness, but its low grinding ratio indicates that the formed interface layer is too brittle. Yttrium significantly improves the flexural strength of the sample, but its grinding ratio improvement is limited, indicating that a clean physical interface does not equate to a strong chemical interface. The sample with added zirconium shows a significant increase in grinding ratio, but the resulting decrease in flexural strength indicates a large internal stress or compatibility issue between the ZrC interface layer and the tungsten-rhenium matrix, leading to a decrease in the overall strength and toughness of the material and posing an application risk. Titanium, while improving the grinding ratio, has little impact on the flexural strength and Vickers hardness of the substrate, and is therefore selected as an interface bonding enhancer.

[0043] Example 2 Reference Figures 1-4 This is the second embodiment of the present invention. After determining the raw material system, it is necessary to optimize the proportions of each component in order to achieve the theoretically optimal performance of the material.

[0044] 2.1 Optimization of the ratio of different diamonds Nanodiamonds play a dual role in composite material systems. Firstly, they act as a microfiller, filling the tiny gaps between large diamond particles and the metal matrix powder to improve the density and matrix hardness of the final material. Secondly, they act as a dispersed reinforcing phase, hindering the growth of matrix grains during sintering and further strengthening the matrix. Insufficient addition results in insignificant filling and reinforcing effects, with limited improvement on the overall material performance. Conversely, excessive addition leads to severe agglomeration of the nanoparticles during mixing due to their high surface energy. These agglomerates become inherent defects within the material, reducing its mechanical properties, particularly flexural strength and toughness. Using 100 parts by mass of large diamond particles as a baseline, multiple experimental groups were established with nanodiamond addition amounts ranging from 3 to 15 parts in 1-part increments, while keeping other components constant.

[0045] The effect of additive dosage on material properties was comprehensively analyzed by testing the density, hardness, three-point bending strength, and grinding ratio of the samples.

[0046] Test results are as follows Figure 1 As shown, through data fitting calculations, the maximum coordinates for density are 6.8 parts; the maximum coordinates for flexural strength are 5.7 parts; the maximum coordinates for Vickers hardness are 9.6 parts; and the maximum coordinates for grinding ratio are 7.3 parts. Considering that grinding ratio is a decisive indicator of the material's final service life, and flexural strength is key to ensuring high tool reliability and avoiding brittle fracture, these two should have higher weights in the comprehensive performance evaluation. Through weighted average calculation (with the weights for grinding ratio and flexural strength set at 0.35, and density and hardness set at 0.15), the theoretically optimal addition amount for comprehensive performance is 7.1 parts. Considering the weighing accuracy and operational convenience of powder proportioning in industrial production, the optimal addition amount of nanodiamond is finally determined to be 7 parts.

[0047] 2.2 Optimization of Titanium Powder Addition Amount Titanium, as an interfacial bonding enhancer, directly determines the thickness and coverage of the TiC interfacial layer formed during sintering, playing a crucial role in the retention force of diamond and the final performance of the material. Insufficient addition leads to incomplete interfacial reaction, resulting in a discontinuous or excessively thin carbide layer and insufficient interfacial bonding strength. Conversely, excessive addition, with its excessive titanium or the resulting thick and brittle TiC layer, not only consumes too much diamond but may also form brittle intermetallic compounds in the matrix or become new crack initiation sources due to excessive thermal mismatch stress between the interfacial layer and the matrix, thus reducing the overall mechanical properties of the material. Based on the established optimal addition amount of 7 parts of nanodiamond, multiple experimental groups with titanium powder addition amounts ranging from 1 to 10 parts were set up, using 100 parts by mass of large-particle diamond as a baseline.

[0048] X-ray diffraction (XRD) was performed on surface-modified diamond samples prepared with different titanium contents. Using specialized phase analysis software, the integrated area of ​​the TiC characteristic peaks in the spectra of each sample was calculated and normalized to the total integrated area of ​​the spectra to obtain the relative TiC content values.

[0049] After each group of samples is made into a final product, it is also necessary to test the hardness, three-point bending strength and grinding ratio to evaluate the impact of different interfacial reaction degrees on the actual service performance of the material.

[0050] Test results are as follows Figure 2As shown, with the increase of titanium powder addition, the relative content of TiC also steadily increases and gradually approaches saturation. This process is inevitably accompanied by potential defects caused by the formation of brittle phases or excessively thick TiC interface layers in the matrix due to excessive titanium. By fitting and calculating three sets of data—hardness, bending strength, and grinding ratio—the maximum value coordinates for hardness are 4.2 parts; the maximum value coordinates for bending strength are 3.3 parts; and the optimal addition amount for the grinding ratio is 5.8 parts.

[0051] By performing a weighted average calculation (with the weights for grinding ratio and bending strength set at 0.4, and Vickers hardness set at 0.2), the theoretically optimal addition amount for comprehensive performance was determined to be 4.6 parts. Considering the precision required for industrial production, the optimal addition amount of titanium powder was determined to be 5 parts.

[0052] 2.3 Optimization of Tungsten-Rhenium Pre-alloying Ratio Rhenium, as a key toughening element, directly affects the intrinsic ductile-brittle transition behavior and mechanical properties of tungsten matrices. Too low a rhenium content in the alloy results in insignificant toughening and fails to effectively suppress tungsten brittleness; while too high a rhenium content not only drastically increases raw material costs but may also lead to a decrease in material toughness due to the formation of brittle intermetallic compounds such as the σ phase. Based on the established optimal addition amounts of nanodiamond and titanium powder, multiple experimental groups with rhenium contents ranging from 1% to 10% were established, with a total mass of 100 parts of tungsten-rhenium pre-alloyed powder.

[0053] The effects of additive dosage on material properties were analyzed by examining fracture toughness, flexural strength, Vickers hardness, and grinding ratio.

[0054] The test results are shown in Figure 3. Through fitting, the maximum value of bending strength is 5.8%; the maximum value of fracture toughness is 7.2%; and the maximum value of grinding ratio is 6.8%. The weights of grinding ratio, bending strength, and fracture toughness are set to 0.35, 0.3, and 0.25, respectively, and the weight of Vickers hardness is set to 0.1. The theoretical optimal addition amount for comprehensive performance is calculated to be 6.87%. Considering the precision required for industrial applications, 7% is selected as the optimal rhenium content in the tungsten-rhenium pre-alloy.

[0055] 2.4 Optimization of the binder-to-diamond ratio Unlike ordinary abrasives that pursue self-sharpening, the core concept of superhard rollers lies in providing mechanical hold, efficient heat dissipation, and impact protection for diamond through a high content of strong and tough metal binder, thereby achieving an ultra-long service life and shape retention. Under this design philosophy, the ratio of diamond to binder is the key to determining its final performance: too low a diamond content will result in insufficient cutting ability and low dressing efficiency; while too high a diamond content will weaken the continuity of the binder matrix, reducing its coating and support effect on the diamond, and deteriorating the overall strength, toughness, and thermal conductivity of the material, which contradicts the original design intention of long service life. With the total mass of diamond and tungsten-rhenium alloy as 100 parts, multiple experimental groups were set up with diamond additions ranging from 20 parts to 80 parts in increments of 5 parts.

[0056] In addition to evaluating sample lifespan by performing a grinding ratio (G-value) test, it is also necessary to record the total grinding time while conducting the grinding ratio test, and calculate the material removal rate per unit time based on the measured workpiece removal volume. A triaxial piezoelectric force sensor also needs to be installed on the grinding test machine's worktable to collect and record the normal and tangential force signals throughout the grinding process in real time. By analyzing the average and standard deviation of the force signal curves, and through weighted calculation, these two parameters are combined into a dimensionless grinding force comprehensive index to evaluate the roller sharpness and the stability of the grinding process.

[0057] A high-precision 3D surface profilometer is used to scan the surface morphology of a standard workpiece after grinding, acquiring its digitized 3D surface data. This data is then processed in a computer. First, a reference average plane is fitted using the least squares method, and the variance of the height values ​​of all measured points on the surface relative to this reference plane is calculated. To eliminate the influence of dimensions and facilitate comparison, this variance value is ratioed to the square of a preset reference length (e.g., the single feed depth set in grinding), thus obtaining a dimensionless surface roughness index.

[0058] Test results are as follows Figure 4 As shown, the maximum coordinates of the grinding ratio are 51.3%; the starting coordinates of the material removal rate reaching its saturation plateau region are approximately 66.5%; and the minimum coordinates of the surface roughness index and the comprehensive grinding force index are 49.5% and 48.8%, respectively.

[0059] To achieve optimal overall performance—that is, maximizing tool life (high G-value) while ensuring high cutting efficiency (high MRR) and excellent machining quality (low index value)—the weight of the grinding ratio was set to 0.4, and the weights of material removal rate, surface roughness index, and grinding force index were each set to 0.2. This resulted in a theoretically optimal diamond content of 53.8% for overall performance.

[0060] Considering the convenience of batching in industrial production, a diamond to binder ratio of 11:9 was ultimately selected as the final optimized ratio.

[0061] Example 3 Reference Figure 4 and Figure 5 This is the third embodiment of the present invention. Formulations obtained under laboratory conditions often fail to fully replicate the optimal laboratory results when transferred to large-scale production equipment due to size effects or scale-up effects. Therefore, key parameters of the core process steps need to be recalibrated and optimized.

[0062] 3.1 Diamond Surface Modification Titanium powder and large diamond particles were added to a high-energy ball mill at a mass ratio of 1:15-25. Zirconia grinding balls of 5 mm were added at a ball-to-powder ratio of 10:1. The milling was carried out continuously at 200-400 prm for 2-6 hours under an argon protective atmosphere, so as to uniformly and densely coat the surface of the diamond particles with titanium powder, forming a metallic coating that provides a material basis for subsequent in-situ reactions.

[0063] 3.2 Composite Powder Mixing Take 110-130 parts of titanium-coated large-particle diamond powder, 90-110 parts of tungsten-rhenium pre-alloyed powder (rhenium content 5-9%), and about 6-12 parts by weight of nanodiamond, and add them together to a three-dimensional motion mixer. Under an argon protective atmosphere, mix continuously at a speed of 40-60 rpm for 6-8 hours to obtain a composite powder with uniformly distributed components for subsequent molding and sintering.

[0064] 3.3 Optimization of Spark Plasma Sintering (SPS) Process Parameters The composite powder is filled into a high-purity graphite mold manufactured according to the product drawings. After vibration compaction, the assembled mold is placed in the cavity of a spark plasma sintering (SPS) furnace. The rapid heating and short holding time characteristics of SPS achieve material densification while minimizing thermal damage to diamond. Before sintering, the furnace chamber is evacuated to below 5 × 10⁻³ Pa and a pre-pressure of 4–6 MPa is applied. Subsequently, the temperature is increased from room temperature to 750–850 °C at a rate of 100 °C / min, during which the axial pressure increases linearly from 4–6 MPa to 40–60 MPa.

[0065] For the W-Re-Ti-diamond composite system, according to the phase diagram and related kinetic data, an axial pressure of no less than 50 MPa is required to ensure the final high density. Simultaneously, to maintain powder stability and gradually compact the material during heating, the pressure should be linearly applied to this final value after the material begins to exhibit plasticity (approximately 800 °C). Titanium and carbon begin to undergo a significant in-situ reaction to form TiC above approximately 900 °C, while complete densification of the tungsten-rhenium matrix requires a sintering temperature of 1200–1300 °C. The kinetic parameters of the sintering process, namely the heating rate from 750–850 °C to 1200–1300 °C and the holding time at 1200–1300 °C, become key variables controlling the final microstructure and properties of the material.

[0066] The heating rate was set from 10 to 90°C / min, with a step size of 10°C / min; the holding time was set from 2 to 16 min, with a step size of 2 min. The influence of these parameters on the finished product performance was analyzed by measuring sample density, three-point bending strength, Vickers hardness, and grinding ratio.

[0067] Test results are as follows Figure 4 and Figure 5 As shown, within the process range where the heating rate is below 60℃ / min and the holding time is above 6 minutes, the system receives sufficient heat input, which facilitates atomic diffusion and the elimination of pores, resulting in a highly dense state where the actual density of the samples approaches the theoretical density. Through data fitting, the maximum coordinates of Vickers hardness were calculated to be (52.5, 6.3); the maximum coordinates of three-point bending strength were (31.8, 8.5); and the maximum coordinates of grinding ratio were (41.2, 8.1).

[0068] The grinding ratio is the basis for directly measuring the performance of the tool under actual working conditions. Therefore, its weight coefficient is set to 0.4, the weight of the bending strength as a reliability guarantee is set to 0.4, and the weight of the Vickers hardness as a basic physical property is set to 0.2. Through weighted calculation, the theoretical optimal point coordinates are (39.7, 7.9). Considering the accuracy of equipment control and the convenience of operation in industrial production, the heating rate of the SPS sintering process is finally determined to be 40℃ / min, and the holding time is 8min.

[0069] 3.4 Post-processing After sintering and cooling, the sintered roller blank is removed from the mold. The roller's outline, inner bore, and working surface are then precision-finished using wire electrical discharge machining (EDM) or laser processing to remove any trace graphite residue and sintering marks, ensuring that dimensional and geometric tolerances meet design standards. Following contour machining, the roller's working surface is polished with fine polishing paste until its surface roughness meets specific usage requirements.

[0070] Example 4 Reference Figure 6 This is the third embodiment of the present invention. This embodiment provides a flowchart for the preparation of an ultrahard, wear-resistant diamond roller, specifically including the following steps: Titanium powder and large diamond particles were added to a high-energy ball mill at a mass ratio of 1:20. Zirconia grinding balls with a diameter of 5 mm were added to the milling jar at a ball-to-powder ratio of 10:1. The milling jar was evacuated and filled with high-purity argon as a protective atmosphere, and then ball milling was continuously performed at 300 rpm for 4 hours. This resulted in a uniform and dense titanium metal coating on the surface of the diamond particles, yielding surface-modified large diamond particles.

[0071] By weight, 120 parts of surface-modified large-particle diamond, 100 parts of tungsten-rhenium pre-alloyed powder with a rhenium content of 7%, and 8 parts of nanodiamond were added together into a three-dimensional motion mixer. Under argon protection, the mixture was continuously mixed at 50 rpm for 8 hours to obtain a composite powder with highly uniform distribution of each component.

[0072] The composite powder was filled into a high-purity graphite mold precisely machined according to the product drawings. After vibration compaction, the entire mold assembly was placed inside the SPS furnace chamber. The furnace chamber was evacuated to below 5 × 10⁻³ Pa, and a pre-pressure of 5 MPa was applied to the mold. The program was started, heating from room temperature to 800°C at a rate of 100°C / min, during which the axial pressure linearly increased from 5 MPa to 50 MPa. After reaching 800°C, heating was continued at a rate of 40°C / min to a sintering temperature of 1250°C. After holding at 1250°C for 8 minutes, heating was stopped, and the furnace was cooled under pressure.

[0073] The cooled sintered body is removed from the graphite mold to obtain a roller blank. The outer contour and inner hole of the roller are precision machined using wire electrical discharge machining (EDM), followed by laser finishing of the working surface. After contour machining, the working surface of the roller is polished multiple times with fine diamond polishing paste until it reaches the designed surface finish, ultimately yielding the finished ultra-hard wear-resistant diamond roller.

[0074] Testing revealed that the resulting superhard wear-resistant diamond roller had a density of 12.28 g / cm³, a Vickers hardness of 1842 HV, a three-point bending strength of 1300 MPa, and a fracture toughness of 15.6 MPa. The grinding ratio (G value) is 290.

[0075] In summary, the diamond roller produced by this invention has good comprehensive mechanical properties and service performance. Its internal structure is dense, and it has excellent wear resistance and resistance to external loads. It has excellent impact resistance and crack propagation inhibition capabilities, which greatly improves its reliability under high load and dynamic working conditions, avoids brittle fracture, and its long service life gives it good economic benefits.

[0076] Using rhenium-containing tungsten-based pre-alloyed powder as the binder matrix, the brittleness of traditional tungsten matrices is addressed through the rhenium effect, providing a high-strength and tough load-bearing skeleton for the entire roller. Through the in-situ reaction of active titanium, a continuous TiC metallurgical bonding interface layer is formed between large diamond particles and the tungsten-rhenium matrix. Fixing the diamond onto the matrix solves the problem of premature abrasive detachment caused by insufficient interfacial bonding in traditional tools, significantly improving the grinding ratio. Nanodiamonds are dispersed throughout the grain boundaries and interiors of the tungsten-rhenium matrix, effectively filling micropores and providing significant dispersion strengthening and grain refinement, thus increasing the material's density and hardness. By adjusting the process parameters of spark plasma sintering, performance loss is minimized.

[0077] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing an ultrahard, wear-resistant diamond roller, characterized in that... Includes the following steps: S1. Titanium powder and large diamond particles are added to a high-energy ball mill at a mass ratio of 1:15~25. Under a protective atmosphere, the titanium powder is coated on the surface of the diamond particles to form surface-modified large diamond particles. S2, by weight, 110-130 parts of the surface-modified large-particle diamond, 90-110 parts of tungsten-rhenium pre-alloy powder with a rhenium content of 5-9%, and 6-12 parts of nano-diamond are added to a three-dimensional motion mixer and mixed under a protective atmosphere to prepare a composite powder. S3 The composite powder is loaded into a graphite mold, compacted, and then placed into a spark plasma sintering furnace. Vacuum is drawn and pre-pressed, preheated and pressurized, and then heated to the sintering temperature at 30~50℃ / min and held for 6~10min. After the S4 sintering is completed and cooled, it is taken out and surface-processed to obtain the superhard wear-resistant diamond roller.

2. The method for preparing the superhard wear-resistant diamond roller according to claim 1, characterized in that, In step S1, the mass ratio of the titanium powder to the large diamond particles is 1:

20.

3. The method for preparing the superhard wear-resistant diamond roller according to claim 1, characterized in that, In step S2, the amount of surface-modified large-particle diamond is 120 parts, the amount of tungsten-rhenium pre-alloyed powder is 100 parts, and the amount of nano-diamond added is 8 parts.

4. The method for preparing the superhard wear-resistant diamond roller according to claim 1, characterized in that, The rhenium content in the tungsten-rhenium pre-alloyed powder is 7%.

5. The method for preparing the superhard wear-resistant diamond roller according to claim 1, characterized in that, In step S3, the heating rate of the heating process is 40℃ / min, and the heat preservation process lasts for 8 minutes.

6. The method for preparing the superhard wear-resistant diamond roller according to claim 1, characterized in that, The protective atmosphere is one or more of argon, nitrogen, or high vacuum; in step S1, the mixing ball milling process of the high-energy ball mill is continuous ball milling at 200~400 prm for 2~6 hours.

7. The method for preparing the superhard wear-resistant diamond roller according to claim 1, characterized in that, In step S2, the operating parameters of the three-dimensional motion mixer are a rotation speed of 40~60 rpm and a mixing time of 6~8 hours.

8. The method for preparing a superhard wear-resistant diamond roller according to claim 1, characterized in that, In step S3, the vacuum degree of the electro-plasma sintering furnace is below 5×10⁻³Pa, and a pre-pressure of 4~6MPa is applied to the material in the graphite mold; the target preheating temperature is 750~850℃, during which the force applied to the material is increased to 40~60MPa; and the sintering temperature is 1200~1300℃.

9. The method for preparing a superhard wear-resistant diamond roller according to claim 1, characterized in that, In step S4, the surface processing includes: using wire electrical discharge machining and laser processing to refine the outer contour, inner hole, and working surface of the roller; and using fine polishing paste to polish the working surface of the roller.

10. A superhard wear-resistant diamond roller, prepared by any one of claims 1 to 9, characterized in that, The prepared superhard wear-resistant diamond roller has a bonding interface layer composed of titanium carbide between the large diamond particles and the tungsten-rhenium metal matrix; the nanodiamonds are dispersed in the grain boundaries and within the grains of the tungsten-rhenium metal matrix.

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