A composite coating diamond roller and a method for manufacturing the same

Abstract

The application discloses a kind of composite coating diamond roller and its preparation method in the technical field of precision grinding processing, the method first mixes artificial diamond micro powder with binder powder including electrolytic copper powder, carbonyl nickel powder, cobalt powder and special additives;The special additive is molybdenum-tungsten composite oxide modified boron nitride powder and zirconium hafnium silicon oxide composite microspheres.Subsequently, mixed powder is filled into the annular groove of steel roller base body, and a compact is obtained by vacuumizing and cold isostatic pressing forming.Two-step vacuum sintering is carried out on the compact: first, heat preservation at a lower temperature, then heat preservation at a higher temperature, and finally, furnace cooling.The product is obtained by external grinding and edge trimming.The method optimizes the composition of binder and sintering process, and improves the holding force of metal binder on diamond and the comprehensive performance of coating by using special additives, significantly improving the wear resistance, thermal stability and service life of the roller.

Description

Technical Field

[0001] This invention relates to the field of precision grinding technology, specifically to a composite coated diamond roller and its preparation method. Background Technology

[0002] Diamond rollers, as core tools in the field of superhard material processing, play an indispensable role in precision grinding, profile grinding, and the precision machining of various hard and brittle materials and high-strength alloys. Their performance directly determines the surface quality, shape accuracy, and production efficiency of the workpiece. An ideal coated diamond roller not only requires extremely high hardness and wear resistance to withstand the severe wear during processing, but also demands excellent holding power of the metal binder for the diamond particles, preventing premature detachment under high-speed, high-pressure processing conditions, thus ensuring the roller's longevity and stability. As modern manufacturing continues to develop towards higher precision, higher efficiency, and higher reliability, more stringent requirements are being placed on the comprehensive performance of diamond rollers. Traditional manufacturing processes and material systems are gradually reaching their limits, necessitating breakthroughs in performance through material innovation and process optimization.

[0003] Currently, the metal bond systems widely used in diamond rollers are mostly based on elemental or alloy powders such as copper, nickel, and cobalt. These binders perform well in conventional machining due to their good sintering properties, moderate hardness, and certain wettability of diamond. However, when faced with increasingly complex machining conditions, such as high temperature, high load, and long-term continuous operation, the limitations of traditional binders become apparent. On the one hand, the chemical bonding and mechanical interlocking strength between the metal phase and diamond particles is limited. Under cyclic thermal and mechanical stress impacts, the interface easily becomes a weak point, leading to loosening or even detachment of diamond particles, resulting in a rapid loss of accuracy in the roller's working surface. On the other hand, the softening and oxidation tendency of some metal binders at high temperatures also weakens their overall support capacity, reducing the holding effect on the diamond. Although the industry has tried to improve performance by adjusting the metal ratio and introducing a single reinforcing phase (such as carbides, borides, etc.), improving one property may often sacrifice other properties, such as increasing the brittleness of the binder or increasing the sintering temperature. It is difficult to achieve synergistic optimization and balance between wear resistance, toughness, thermal stability and good sintering activity.

[0004] Therefore, developing a novel composite binder system to fundamentally enhance the metal matrix's ability to hold diamond while simultaneously improving the high-temperature strength, creep resistance, and thermochemical stability of the binder coating itself has become a key technological direction for improving the performance of high-end diamond rollers. This requires that the introduced reinforcing phase or modifier not only be well-compatible with the metal matrix and form a stable bond during sintering, but also effectively bridge the metal and diamond through unique microstructures or interfacial interactions, relieving interfacial stress and inhibiting performance degradation at high temperatures. This invention is based on this urgent need, focusing on the careful design and preparation of specific composite functional additives and their introduction into conventional metal binders. The aim is to achieve a synergistic enhancement of the overall performance of diamond roller coatings without significantly altering mature sintering processes, thus meeting the urgent demand for high-performance superhard grinding tools in advanced manufacturing. Summary of the Invention

[0005] The purpose of this invention is to provide a composite coated diamond roller and its preparation method, which solves the technical problems of existing traditional metal-bonded diamond rollers under high temperature and high load conditions, such as insufficient holding force of diamond particles, poor high temperature strength and creep resistance of the binder, resulting in short wear life and easy instability of roller surface accuracy.

[0006] The present invention achieves the above objectives through the following technical solutions: A method for preparing a composite coated diamond roller, comprising the following steps: S1. By weight, 35-45 parts of synthetic diamond micro powder and binder powder are mixed to obtain a mixture; the binder powder comprises 20-30 parts of electrolytic copper powder, 15-25 parts of carbonyl nickel powder, 8-12 parts of cobalt powder, 1.5-3.0 parts of molybdenum-tungsten composite oxide modified boron nitride powder and 2.0-4.0 parts of zirconium-hafnium silicon oxide composite microspheres; the mixture is placed in a mixer and stirred to obtain a mixed powder; S2. The mixed powder is loaded into the annular groove of the pre-formed steel roller matrix, and vacuumed to ≤10Pa. It is then cold isostatically pressed to obtain a compact. The compact is placed in a vacuum sintering furnace, heated to 915-925℃ and held, then heated to 1045-1055℃ and held, and cooled to room temperature with the furnace. The compact is then ground on the outer cylindrical surface and the cutting edge is trimmed.

[0007] In this invention, the performance of the composite-coated diamond roller is improved through synergistic interface engineering. Molybdenum-tungsten composite oxide-modified boron nitride powder and zirconium-hafnium silicon oxide composite microspheres are added to a metal binder system. After prolonged mechanical mixing, the modifier is uniformly dispersed in copper, nickel, and cobalt powders. Following cold isostatic pressing, during vacuum sintering, the molybdenum-tungsten composite oxide forms a chemical bonding interface on the diamond particle surface, significantly enhancing the bonding strength between the diamond and the metal matrix. Simultaneously, the zirconium-hafnium silicon oxide microspheres melt at high temperature to form a glassy phase, filling the coating pores and inhibiting crack propagation. Precise segmented control of the sintering temperature ensures the densification of the metal matrix and the activation of the modifier, resulting in a composite coating that combines high hardness, excellent wear resistance, and thermal stability. This process, through the synergistic effect of the modifier, solves the problems of interface weakening and high-temperature failure in traditional diamond rollers, enabling the roller to exhibit significant performance advantages in precision grinding applications.

[0008] According to a preferred embodiment of the present invention, in step S1, the stirring time is 12-14 hours.

[0009] According to a preferred embodiment of the present invention, in step S2, the time for holding the temperature at 1045-1055°C is 60-80 minutes.

[0010] According to a preferred embodiment of the present invention, the preparation method of the molybdenum-tungsten composite oxide modified boron nitride powder includes: A1. Add hexagonal boron nitride powder to deionized water and disperse by ultrasonication; then add ammonium heptamolybdate and sodium tungstate and stir; adjust the pH to 9.4-9.6 with concentrated ammonia, raise the temperature to 84-86℃ and stir continuously; add boric acid dropwise and continue the reaction to obtain the reaction mixture; A2. Cool the reaction mixture to room temperature, centrifuge to collect the precipitate, wash the precipitate with ethanol and deionized water in sequence, and dry it under vacuum at 58-62℃ to obtain a solid product; place the solid product in a tube furnace, heat it to 895-905℃ under a nitrogen atmosphere, keep it at that temperature, cool it naturally, grind and sieve it.

[0011] In this invention, during the preparation of boron nitride powder modified with molybdenum-tungsten composite oxide, hexagonal boron nitride powder is ultrasonically dispersed in deionized water and then dissolved together with molybdenum and tungsten source compounds in an alkaline environment. By adjusting the solution pH to a weakly alkaline range, the molybdenum-tungsten compounds undergo hydrolysis to form an active oxide precursor. Simultaneously, the addition of boric acid promotes the participation of boron in the interfacial reaction. Under continuous heating, the precursor uniformly adheres to the boron nitride surface, forming a molybdenum-tungsten oxide coating layer. Subsequent cooling and washing steps remove unreacted impurities. The dried precursor is then calcined at high temperature in an inert atmosphere, causing the molybdenum-tungsten oxide to thermochemically bond with the boron nitride substrate, forming a stable composite structure. This process, through precise control of temperature and time, avoids structural damage to boron nitride, ensuring that the molybdenum-tungsten oxide uniformly covers the surface of the boron nitride particles in a thin film, providing key active sites for subsequent interfacial enhancement.

[0012] According to a preferred embodiment of the present invention, in step A1, the reaction continues for 2-4 hours.

[0013] According to a preferred embodiment of the present invention, in step A2, the time for holding the temperature at 895-905°C is 2-4 hours.

[0014] According to a preferred embodiment of the present invention, the method for preparing the zirconium-hafnium silicon oxide composite microspheres includes: B1. Dissolve tetraethyl orthosilicate in anhydrous ethanol, add deionized water and concentrated hydrochloric acid, stir at room temperature to obtain a sol; dissolve zirconium oxychloride and hafnium chloride together in deionized water, add dropwise to the sol, start shear emulsification to obtain a microemulsion; B2. Add ammonia dropwise to the microemulsion to adjust the pH to 7.8-8.2, and continue stirring; collect the microspheres by centrifugation, wash the microspheres with ethanol, and dry them at 78-82℃ to obtain the dried product; place the dried product in a muffle furnace, heat it to 745-755℃ in air atmosphere, hold it at that temperature, then heat it to 1095-1105℃ and hold it at that temperature, and then let it cool naturally.

[0015] In this invention, the preparation of zirconium-hafnium silicon oxide composite microspheres is based on sol-gel technology and microemulsion process. Tetraethyl orthosilicate is hydrolyzed in acidic ethanol solution to generate silica sol. After an aqueous solution of zirconium oxychloride and hafnium chloride is added dropwise to the sol, molecular-level uniform dispersion is achieved through high-speed shear emulsification, forming a stable microemulsion system. Ammonia water is used to adjust the pH to a weakly alkaline environment, triggering the co-hydrolysis and condensation reaction of silicon, zirconium, and hafnium ions to form a gel network structure. Under continuous stirring at room temperature, the gel gradually matures into microspheres. After centrifugation and washing with ethanol to remove organic residues, the dried microspheres undergo a two-stage heat treatment in air: a low-temperature stage to remove organic components and a high-temperature stage to promote oxide crystallization. This process, through gradient temperature control, allows zirconium, hafnium, and silicon elements to form a homogeneous composite oxide structure inside the microspheres, avoiding elemental segregation, and ultimately obtaining composite microspheres with high density and thermal stability.

[0016] According to a preferred embodiment of the present invention, in step B1, the time for initiating shear emulsification is 5-10 minutes.

[0017] According to a preferred embodiment of the present invention, in step B2, the time for holding the temperature at 745-755°C is 3-4 hours.

[0018] The present invention also provides a composite coated diamond roller prepared according to the method for preparing the composite coated diamond roller.

[0019] The beneficial effects of this invention are as follows: The composite coated diamond roller and its preparation method provided by this invention achieve a significant leap in the overall performance of the roller coating by introducing two specifically designed composite functional additives into the traditional metal binder system and optimizing the sintering process. The technical effects are specific and comprehensive.

[0020] Firstly, regarding the inherent strengthening of the coating material, the synergistic addition of molybdenum-tungsten composite oxide-modified boron nitride powder and zirconium-hafnium silicon oxide composite microspheres optimizes the structure and performance of the binder at multiple scales. On one hand, the molybdenum-tungsten composite oxide-modified boron nitride powder not only mitigates the thermal damage tendency of the binder during high-speed grinding due to its inherent high thermal stability and lubricity, but more importantly, the molybdenum-tungsten composite oxide loaded on its surface can undergo a more active interfacial reaction with the metal matrix during sintering, enhancing the chemical bonding force with metals such as copper, nickel, and cobalt. This strong interfacial bonding makes the powder stable and dispersed in the metal matrix, becoming an effective reinforcing phase and improving the overall stiffness and high-temperature strength of the binder. On the other hand, the zirconium-hafnium silicon oxide composite microspheres, with their unique spherical structure and ceramic nature, play a dual role in the coating, similar to "bearings" and "pinning". Its spherical shape helps reduce stress concentration during cold pressing and sintering, promoting powder flow and densification. Its high hardness and high melting point allow it to be firmly embedded in the metal matrix after sintering. It can strengthen the matrix by hindering dislocation movement, and it can also work synergistically with the aforementioned modified boron nitride powder to form a three-dimensional reinforcing network. This significantly inhibits the plastic deformation and creep of the binder under high temperature and high load, thus providing a more solid and durable support substrate for diamond particles.

[0021] Secondly, this invention demonstrates superior advantages in terms of interface bonding and process adaptability. The two-step vacuum sintering process is a key step in ensuring performance improvement. The first step, holding at a relatively low temperature, allows the metal powder particles to diffuse sufficiently and undergo preliminary alloying in the solid state, while simultaneously enabling the functional additives to begin establishing a preliminary bond with the metal interface, laying a uniform microstructure foundation for the subsequent high-temperature stages. The second step, holding at an even higher temperature, is carried out near the melting points of certain metal components, promoting the appropriate generation of the liquid phase and achieving final densification under capillary forces. During this process, the interfacial reaction between the functional additives and the metal matrix is ​​more complete, forming a strong metallurgical bond or chemical bond. Of particular importance is that the good stability of molybdenum-tungsten composite oxide and zirconium-hafnium silicon oxide at high temperatures ensures that they will not undergo adverse decomposition or phase transformation during sintering. On the contrary, they may promote the reaction with trace carbon elements on the diamond surface or form a tighter mechanical intercalation, thereby comprehensively strengthening the multidimensional interface between "diamond-functional phase-metal matrix", greatly improving the binding force of the binder on diamond particles, and effectively preventing premature particle detachment.

[0022] Finally, the synergistic innovation of the aforementioned materials and processes ultimately translates into a comprehensive improvement in the end-stage performance of the diamond roller. The resulting diamond roller exhibits significantly enhanced wear resistance in its working coating, maintaining stable surface accuracy during prolonged continuous grinding operations and significantly extending its service life. Due to the excellent high-temperature strength and thermal stability of the binder, the roller demonstrates outstanding resistance to softening under the high-temperature environment generated in the grinding zone, reducing heat-induced deformation and accelerated wear, thereby ensuring the consistency of the machined workpiece dimensions and superior surface quality. Simultaneously, the improved toughness of the binder reduces the tendency of the coating to crack under internal stress or impact loads, enhancing the reliability of the roller. In summary, this invention, through ingenious material composite and precise process control, successfully prepares a composite-coated diamond roller that combines ultra-high wear resistance, excellent toughness, outstanding thermal stability, and durable surface accuracy, effectively meeting the urgent demand for high-performance grinding tools in modern precision and ultra-precision machining fields, and possessing significant industrial application value. Detailed Implementation

[0023] The following detailed embodiments are only used to further illustrate this application and should not be construed as limiting the scope of protection of this application. Those skilled in the art can make some non-essential improvements and adjustments to this application based on the above application content.

[0024] Example 1 Preparation of boron nitride powder modified with molybdenum-tungsten composite oxide: First, accurately weigh 10.0 g of hexagonal boron nitride powder and add it to a beaker containing 200 mL of deionized water. Place the beaker in an ultrasonic cleaner and ultrasonically disperse it at 25 °C for 30 min to form a uniform suspension. Then, add 2.0 g of ammonium heptamolybdate and 1.5 g of sodium tungstate to the suspension sequentially. Place the beaker on a magnetic stirrer and stir continuously at 500 rpm for 20 min to completely dissolve and mix the solids. Next, slowly add concentrated ammonia solution dropwise while stirring until the pH of the mixed solution stabilizes at 9.5. Transfer the beaker to an oil bath, heat it to 85 °C and maintain this temperature while stirring at 500 rpm. After the temperature stabilizes, add 50 mL of 1.0 mol / L boric acid aqueous solution dropwise at a rate of approximately 1 mL / min using a constant pressure dropping funnel. After the addition was complete, the reaction mixture was stirred at 85℃ for 3.0 h to obtain a reaction mixture containing precipitate. After the reaction was complete, the beaker was transferred to a cold water bath and rapidly cooled to room temperature. The cooled mixture was transferred to a centrifuge tube and centrifuged at 8000 rpm for 10 min, and the supernatant was carefully discarded. The collected precipitate was washed with 100 mL of anhydrous ethanol and centrifuged three times, then washed with 100 mL of deionized water and centrifuged twice. The washed wet precipitate was transferred to a watch glass and placed in a vacuum drying oven and dried at 60℃ and -0.095 MPa for 12 h to obtain a dry solid precursor. This solid precursor was transferred to an alumina crucible and then placed in the isothermal zone of a tube furnace. The furnace was closed, and high-purity nitrogen (purity ≥99.99%) was introduced at a flow rate of 2.0 L / min for 30 min to replace the air. Subsequently, under a nitrogen atmosphere, the furnace temperature was increased from room temperature to 900℃ at a heating rate of 5℃ / min, and calcined at this temperature for 3.0 h. After calcination, heating was stopped, nitrogen gas was kept circulating, and the furnace was allowed to cool naturally to below 50℃. The crucible was removed, and the calcined block product was ground in an agate mortar and finally passed through a 400-mesh (approximately 38 μm) standard sieve to obtain fine molybdenum-tungsten composite oxide modified boron nitride powder, which was then placed in a desiccator for later use.

[0025] Preparation of zirconium-hafnium silicate composite microspheres: First, 100 mL of anhydrous ethanol was poured into a 250 mL Erlenmeyer flask. 20.0 g of tetraethyl orthosilicate was slowly added under magnetic stirring (300 rpm), and the mixture was stirred for 10 min to ensure homogeneity. Then, 10.0 mL of deionized water and 2.0 mL of concentrated hydrochloric acid (36% by mass) were added sequentially to the flask. The stirring speed was increased to 600 rpm, and the mixture was stirred continuously at 25°C for 2.0 h to obtain a clear and transparent silica sol A, which was then sealed for later use. In a separate 100 mL beaker, 50 mL of deionized water was added. 8.0 g of zirconium oxychloride and 2.0 g of hafnium chloride were accurately weighed and added to the water, and the mixture was magnetically stirred until completely dissolved to obtain a transparent solution B. While vigorously stirring silica sol A (800 rpm), solution B was added dropwise over 15 min using a dropping funnel. After the addition was complete, the mixture was transferred to the processing vessel of a high-speed shear emulsifier and emulsified at 10,000 rpm for 8.0 min to obtain a uniform, slightly milky white mixed sol C. Sol C was transferred back to a 500 mL three-necked flask and placed on a magnetic stirrer. While stirring at 300 rpm, 25% ammonia solution was slowly added dropwise to adjust the pH of the system to 8.0. After adjustment, the mixture was kept at 25°C and stirred for 20.0 h to carry out hydrolysis-condensation and gelation. After the reaction was complete, all materials were transferred to a centrifuge cup and centrifuged at 5000 rpm for 5 min. The supernatant was discarded, and the white gel microspheres at the bottom were collected. The gel microspheres were dispersed and washed with 50 mL of anhydrous ethanol, and centrifuged again. This process was repeated three times. The washed wet gel microspheres were evenly spread in a petri dish and placed in a forced-air drying oven at 80°C for 10 h to obtain dried composite precursor microspheres. The dried product was placed in a corundum crucible and then placed in a muffle furnace. The furnace door was closed, and the temperature was increased from room temperature to 750°C at a rate of 3°C / min under static air atmosphere, and held at this temperature for 3.5 h to completely decompose and remove organic matter. Then, the temperature was increased to 1100°C at a rate of 3°C / min and held at this high temperature for 2.5 h for sintering and crystallization. After sintering, the power was turned off, and the muffle furnace was allowed to cool naturally to room temperature. The crucible was removed, yielding zirconium-hafnium silicon oxide composite microspheres, which were then placed in a desiccator for later use.

[0026] Preparation of composite coated diamond rollers: First, prepare the raw materials. Accurately weigh 40.0g of synthetic diamond micropowder with a particle size of W10. Accurately weigh the following components of the binder powder: 25.0g of electrolytic copper powder (particle size approximately 75μm), 20.0g of carbonyl nickel powder (particle size approximately 3-7μm), 10.0g of cobalt powder (particle size approximately 1-2μm), 2.5g of the above-prepared molybdenum-tungsten composite oxide modified boron nitride powder, and 3.0g of the above-prepared zirconium-hafnium silicon oxide composite microspheres. Add the weighed synthetic diamond micropowder and all binder powder components into a 10L V-type mixer. Close the mixer door, start the equipment, and mix at 15rpm for a total mixing time of 13.0h to ensure the powder reaches a highly uniform state, obtaining mixed powder D. Take a pre-formed No. 45 steel roller base, whose outer surface has been machined with an annular groove with a depth of 2.0 mm and a width of 5.0 mm. Carefully fill the annular groove with mixed powder D and smooth it with a scraper. Place the powder-filled roller base into a special rubber flexible mold, seal it, and place it in the working cylinder of a cold isostatic press. Close the cylinder, start the vacuum pump, and evacuate the vacuum in the mold cavity to 5 Pa and maintain it. Then start the high-pressure pump, increase the pressure to 200 MPa at a pressurization rate of 100 MPa / min, and hold the pressure for 5.0 min. Then depressurize, remove the mold, and take out the compacted blank E from the mold. Place the blank E in a graphite sintering boat, and then place it together in the homogenization zone of a vacuum sintering furnace. Close the furnace door, start the vacuum system, and evacuate the vacuum in the furnace to 5 × 10⁻⁶. -2 Below Pa. The sintering process begins: first, the temperature is increased from room temperature to 920℃ at a rate of 8℃ / min, and held at 920℃ for 30 minutes; then, the temperature is increased to 1050℃ at a rate of 5℃ / min, and held at 1050℃ for 70 minutes; after the holding period, heating is stopped, and the furnace is allowed to cool naturally to below 60℃ under vacuum. The vacuum is broken, and the sintered roller blank F is removed. Finally, the roller blank F is clamped on a precision cylindrical grinding machine, and its outer cylindrical coating is finely ground to meet the dimensional accuracy requirements of the drawing. The working cutting edges are then finely trimmed to obtain the final composite-coated diamond roller product.

[0027] Example 2 The specific implementation method is the same as in Example 1, except that the preparation of the molybdenum-tungsten composite oxide modified boron nitride powder is as follows: 10.0 g of hexagonal boron nitride powder is accurately weighed and added to 200 mL of deionized water, and ultrasonically dispersed at 25 °C for 30 min. 2.2 g of ammonium heptamolybdate and 1.8 g of sodium tungstate are added, and the mixture is stirred at 500 rpm for 20 min. Concentrated ammonia is added dropwise to adjust the pH to 9.4, and the mixture is transferred to an oil bath and heated to 84 °C and maintained. 45 mL of a 1.0 mol / L boric acid aqueous solution is added dropwise at a rate of 1 mL / min. After the addition is complete, the mixture is stirred at 84 °C for 2.0 h. After the reaction is complete, the mixture is cooled to room temperature in a cold water bath. The precipitate is collected by centrifugation at 8000 rpm for 10 min, washed three times with 100 mL of anhydrous ethanol and twice with 100 mL of deionized water. The wet precipitate is dried at 60 °C under a vacuum of -0.095 MPa for 12 h. The dried solid was placed in a tube furnace, and nitrogen gas was introduced (2.0 L / min) for 30 min. The temperature was then increased to 895 °C at 5 °C / min and calcined for 2.0 h. Subsequently, it was naturally cooled under nitrogen. The product was removed, ground, and passed through a 400-mesh sieve to obtain powder.

[0028] Preparation of zirconium-hafnium silicate composite microspheres: 100 mL of anhydrous ethanol was weighed and 18.0 g of tetraethyl orthosilicate was added while stirring at 300 rpm for 10 min. Then, 8.0 mL of deionized water and 1.5 mL of concentrated hydrochloric acid were added sequentially, the stirring speed was increased to 600 rpm, and the mixture was stirred at 25 °C for 2.0 h to obtain silica sol A. In a separate beaker, 50 mL of water was added to dissolve 7.0 g of zirconium oxychloride and 3.0 g of hafnium chloride to obtain solution B. Solution B was added dropwise to solution A while stirring at 800 rpm for 15 min. The mixture was transferred to a shear emulsifier and emulsified at 10000 rpm for 5.0 min to obtain mixed sol C. Solution C was transferred to a three-necked flask, and ammonia was added dropwise while stirring at 300 rpm to adjust the pH to 7.9. The mixture was stirred at 25 °C for 24.0 h. The gel microspheres were collected by centrifugation at 5000 rpm for 5 min and washed three times with 50 mL of anhydrous ethanol. The wet microspheres were dried at 80℃ for 10 hours. The dried product was placed in a muffle furnace and heated to 745℃ at 3℃ / min in static air, held for 4.0 hours, then heated to 1095℃ at 3℃ / min, held for 3.0 hours, and then naturally cooled to obtain composite microspheres.

[0029] Preparation of composite coated diamond rollers: 35.0g of W10 synthetic diamond micropowder was weighed. The following binder powders were weighed: 20.0g electrolytic copper powder, 25.0g carbonyl nickel powder, 12.0g cobalt powder, 1.5g of the above-prepared molybdenum-tungsten composite oxide modified boron nitride powder, and 2.0g of the above-prepared zirconium-hafnium silicon oxide composite microspheres. All powders were added to a V-type mixer and mixed at 15 rpm for 12.0h to obtain a mixed powder. The mixed powder was filled into an annular groove of a steel roller substrate (groove depth 2.0mm, width 5.0mm) and placed into a rubber mold. A vacuum of 8Pa was applied, and the pressure was increased to 200MPa at 100MPa / min in a cold isostatic press and held for 5.0min to obtain a pressed blank. The pressed blank was placed in a vacuum sintering furnace (vacuum degree 5×10⁻⁶). -2 The temperature is increased to 915℃ at 8℃ / min and held for 30 min, then increased to 1045℃ at 5℃ / min and held for 80 min, followed by furnace cooling. The blank is removed and subjected to external cylindrical grinding and cutting edge trimming to obtain the finished roller.

[0030] Example 3 The specific implementation method is the same as in Example 1, except that the preparation of the molybdenum-tungsten composite oxide modified boron nitride powder is as follows: 10.0 g of hexagonal boron nitride powder is accurately weighed and added to 200 mL of deionized water, and ultrasonically dispersed at 25 °C for 30 min. 1.8 g of ammonium heptamolybdate and 1.2 g of sodium tungstate are added, and the mixture is stirred at 500 rpm for 20 min. Concentrated ammonia is added dropwise to adjust the pH to 9.6, and the mixture is transferred to an oil bath and heated to 86 °C and maintained. 55 mL of a 1.0 mol / L boric acid aqueous solution is added dropwise at a rate of 1 mL / min. After the addition is complete, the mixture is stirred at 86 °C for 4.0 h. After the reaction is complete, the mixture is cooled to room temperature in a cold water bath. The precipitate is collected by centrifugation at 8000 rpm for 10 min, washed three times with 100 mL of anhydrous ethanol and twice with 100 mL of deionized water. The wet precipitate is dried at 60 °C under a vacuum of -0.095 MPa for 12 h. The dried solid was placed in a tube furnace, and nitrogen gas was introduced (2.0 L / min) for 30 min. The temperature was then increased to 905 °C at 5 °C / min and calcined for 4.0 h. Subsequently, it was naturally cooled under nitrogen. The product was removed, ground, and passed through a 400-mesh sieve to obtain powder.

[0031] Preparation of zirconium-hafnium silicate composite microspheres: 100 mL of anhydrous ethanol was weighed and 22.0 g of tetraethyl orthosilicate was added while stirring at 300 rpm for 10 min. Then, 12.0 mL of deionized water and 2.5 mL of concentrated hydrochloric acid were added sequentially, the stirring speed was increased to 600 rpm, and the mixture was stirred at 25 °C for 2.0 h to obtain silica sol A. In a separate beaker, 50 mL of water was added to dissolve 9.0 g of zirconium oxychloride and 1.0 g of hafnium chloride to obtain solution B. Solution B was added dropwise to solution A while stirring at 800 rpm for 15 min. The mixture was transferred to a shear emulsifier and emulsified at 10000 rpm for 10.0 min to obtain mixed sol C. Solution C was transferred to a three-necked flask, and ammonia was added dropwise while stirring at 300 rpm to adjust the pH to 8.2. The mixture was stirred at 25 °C for 15.0 h. The gel microspheres were collected by centrifugation at 5000 rpm for 5 min and washed three times with 50 mL of anhydrous ethanol. The wet microspheres were dried at 80℃ for 10 hours. The dried product was placed in a muffle furnace and heated to 755℃ at 3℃ / min in static air, held for 3.0 hours, then heated to 1105℃ at 3℃ / min, held for 2.0 hours, and then naturally cooled to obtain composite microspheres.

[0032] Preparation of composite coated diamond rollers: 45.0g of W10 synthetic diamond micropowder was weighed. The following binder powders were weighed: 30.0g electrolytic copper powder, 15.0g carbonyl nickel powder, 8.0g cobalt powder, 3.0g of the above-prepared molybdenum-tungsten composite oxide modified boron nitride powder, and 4.0g of the above-prepared zirconium-hafnium silicon oxide composite microspheres. All powders were added to a V-type mixer and mixed at 15 rpm for 14.0h to obtain a mixed powder. The mixed powder was filled into an annular groove of a steel roller substrate (groove depth 2.0mm, width 5.0mm) and placed into a rubber mold. A vacuum of 3Pa was applied, and the pressure was increased to 200MPa at 100MPa / min in a cold isostatic press and held for 5.0min to obtain a pressed blank. The pressed blank was placed in a vacuum sintering furnace (vacuum degree 5×10⁻⁶). -2 The temperature is increased to 925℃ at 8℃ / min and held for 30 min, then increased to 1055℃ at 5℃ / min and held for 60 min, followed by furnace cooling. The blank is removed and subjected to external cylindrical grinding and cutting edge trimming to obtain the finished roller.

[0033] Comparative Example 1 The specific implementation method is the same as in Example 1, except that the binder powder does not contain molybdenum-tungsten composite oxide modified boron nitride powder; its mass is made up by an equal amount of electrolytic copper powder. That is, the binder powder contains: 27.5g electrolytic copper powder, 20.0g carbonyl nickel powder, 10.0g cobalt powder, 0g molybdenum-tungsten composite oxide modified boron nitride powder, and 3.0g of zirconium-hafnium silicon oxide composite microspheres prepared in Example 1. The amount of synthetic diamond micropowder used is 40.0g. All other steps and parameters, including the preparation of the mixed powder (mixing for 13.0h), cold isostatic pressing (vacuum degree 5Pa, pressure 200MPa, holding pressure for 5.0min), and vacuum sintering process (holding at 920℃ for 30min, holding at 1050℃ for 70min), are exactly the same as in Example 1.

[0034] Comparative Example 2 The specific implementation method is the same as in Example 1, except that zirconium-hafnium silicon oxide composite microspheres are not added to the binder powder; their mass is made up by an equal amount of carbonyl nickel powder. That is, the binder powder contains: 25.0 g of electrolytic copper powder, 23.0 g of carbonyl nickel powder, 10.0 g of cobalt powder, 2.5 g of the molybdenum-tungsten composite oxide modified boron nitride powder prepared in Example 1, and 0 g of zirconium-hafnium silicon oxide composite microspheres. The amount of synthetic diamond micropowder used is 40.0 g. All other steps and parameters, including the preparation of the mixed powder (mixing for 13.0 h), cold isostatic pressing (vacuum degree 5 Pa, pressure 200 MPa, holding pressure for 5.0 min), and vacuum sintering process (holding at 920℃ for 30 min, and at 1050℃ for 70 min), are exactly the same as in Example 1.

[0035] Comparative Example 3 The specific implementation method is the same as in Example 1, except that the binder powder does not contain molybdenum-tungsten composite oxide modified boron nitride powder and zirconium-hafnium silicon oxide composite microspheres. The mass of the two is made up by equal amounts of electrolytic copper powder and carbonyl nickel powder, respectively. That is, the binder powder contains only: 27.5g electrolytic copper powder, 23.0g carbonyl nickel powder, 10.0g cobalt powder, 0g molybdenum-tungsten composite oxide modified boron nitride powder, and 0g zirconium-hafnium silicon oxide composite microspheres. The amount of synthetic diamond micropowder is 40.0g. All other steps and parameters, such as the preparation of the mixed powder (mixing for 13.0h), cold isostatic pressing (vacuum degree 5Pa, pressure 200MPa, holding pressure for 5.0min), and vacuum sintering process (holding at 920℃ for 30min, holding at 1050℃ for 70min), are exactly the same as in Example 1.

[0036] Performance testing The composite-coated diamond rollers prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance testing according to the following method, which included the following steps: Sample preparation and sampling: All roller samples to be tested were directly used for grinding life testing after final dressing. For hardness, coefficient of thermal expansion and microstructure analysis, appropriately sized sample blocks were cut from the working layer of the roller using an EDM wire cutter, and the test surfaces were ground and polished.

[0037] Grinding life test: Performed on a precision CNC profile grinding machine of model MGK7120×6. The roller to be tested was mounted on the dresser spindle. The workpiece was set as a GCr15 bearing steel ring with an outer diameter of 100mm and a width of 20mm, and its hardness was controlled between 60HRC and 62HRC after heat treatment. The grinding parameters were set as follows: constant workpiece rotation speed of 300r / min, continuous feed speed of the roller along the radial direction of the workpiece of 2μm / s, and 5% concentration water-based synthetic grinding fluid was used for thorough cooling and rinsing. Each roller was continuously dressed and ground until its working profile was measured by an LK-G5000 series laser profilometer. When the maximum wear exceeded 15% of the theoretical value of the initial accurate profile, it was judged as a failure. The total length of the workpiece ground from the start of grinding to failure was recorded in meters (m). This data is the grinding life of the roller.

[0038] Hardness Testing: An FV-700 high-temperature Vickers hardness tester was used. Room temperature hardness testing was conducted at 25℃. For high-temperature hardness testing, the sample was placed in a vacuum heating chamber and heated to 600℃ at a rate of 10℃ / min, held for 15 minutes to ensure temperature uniformity, and then a load was applied and held at 600℃. Vickers hardness tests used a test force of 0.5 kgf (~4.903 N) for a holding time of 15 seconds. Five points were tested on each sample within the effective area. After discarding the maximum and minimum values, the arithmetic mean was taken to obtain the room temperature Vickers hardness value (HV0.5) and the 600℃ high-temperature Vickers hardness value (HV0.5). The high-temperature hardness retention rate was calculated using the following formula: Retention rate (%) = (600℃ hardness value / room temperature hardness value) × 100%.

[0039] Diamond particle holding force assessment (dropout rate statistics): After the grinding life test, the roller sample was ultrasonically cleaned and dried, and then its worn surface was observed under an SU5000 field emission scanning electron microscope. Ten fields of view were randomly selected, each with a magnification of 500x, corresponding to an actual observation area of ​​approximately 0.04 mm². 2 In each field of view, clearly identify and count the regular pits left by the complete detachment of diamond particles. Calculate the total number of pits across 10 fields of view, then divide by the corresponding total observed area (0.4 mm). 2 This yields the number of diamonds detached per unit area, i.e., the detachment rate, expressed in units of diamonds per square millimeter (diamonds / mm). 2 ).

[0040] Thermal expansion coefficient test: A DIL402 ExpedisSelect thermal dilatometer was used. The coating material was processed into cylindrical specimens with dimensions of φ5mm × 25mm. The test was conducted under the protection of flowing high-purity nitrogen (purity ≥99.999%) at a flow rate of 50mL / min. The specimens were heated from 30℃ to 600℃ at a heating rate of 5℃ / min, and the length change curves during the entire heating process were recorded. The instrument software automatically analyzed and calculated the average linear expansion coefficient of the specimens in the temperature range of 30℃ to 600℃. The results are expressed in terms of 10... -6 / ℃ is the unit.

[0041] Test results: Table 1: Test results of each embodiment and comparative example

[0042] As can be seen from Table 1, Examples 1-3, compared with Comparative Examples 1-3, comprehensively and significantly solved the technical problems existing in traditional metal-bonded diamond rollers.

[0043] Specifically, Comparative Example 3, which used only a basic copper-nickel-cobalt metal binder, performed the worst in all key indicators: shortest wear life (2200m), lowest room temperature and high temperature hardness (398HV0.5 and 235HV0.5 respectively), and highest diamond shedding rate (18.2 diamonds / mm). 2 And it has the largest coefficient of thermal expansion (15.0×10⁻⁶). -6 / ℃), which clearly demonstrates the inherent defects of traditional binder systems in terms of interfacial holding force, high-temperature strength and thermal stability.

[0044] Comparative Example 1 (with zirconium-hafnium silicon oxide composite microspheres but without molybdenum-tungsten composite oxide modified boron nitride powder) and Comparative Example 2 (with molybdenum-tungsten composite oxide modified boron nitride powder but without zirconium-hafnium silicon oxide composite microspheres) showed better performance than Comparative Example 3, but both had significant shortcomings. The diamond loss rate of Comparative Example 1 was 12.5 diamonds / mm. 2 The results for Comparative Example 2 are still significantly higher than those for the Examples, indicating a lack of strengthening effect of the molybdenum-tungsten composite oxide modified boron nitride powder on the interfacial bonding, and the metal's holding power over diamond is still insufficient. Meanwhile, the high-temperature hardness (305HV0.5) and retention rate (68.5%) of Comparative Example 2 at 600℃ are significantly lower than those of the Examples, indicating a lack of rigid support and pinning effect of zirconium-hafnium silicon oxide composite microspheres, and the binder matrix has weak resistance to softening and creep at high temperatures.

[0045] In contrast, Examples 1-3, by simultaneously introducing the two specially formulated additives and optimizing the process, achieved a synergistic leap in performance. The wear life (4150-4800 μm) of all examples was approximately 89-118% higher than Comparative Example 3, and significantly higher than any single-additive comparative example, demonstrating a fundamental improvement in the overall wear resistance and lifespan of the coating. The examples achieved the highest levels of room temperature and high-temperature hardness, particularly with a significantly improved high-temperature hardness retention rate (75.3-77.5%), indicating that the binder system effectively maintains strength and rigidity under high-temperature grinding conditions, solving the problem of high-temperature softening. Most importantly, the diamond shedding rate of the examples (5.1-5.9 diamonds / mm) was significantly reduced. 2 The coefficient of thermal expansion was reduced to a minimum, approximately 68-72% lower than that of Comparative Example 3. This directly confirms the revolutionary enhancement of the diamond-bond interface, effectively suppressing premature particle detachment. Furthermore, the average coefficient of linear expansion in the examples (12.1-12.3 × 10⁻⁶) was significantly reduced. -6 The significant decrease in (°C) indicates that the coating has better thermal dimensional stability, which helps to reduce thermal stress and thermal fatigue.

[0046] In summary, the embodiments of the present invention, through the synergistic effect of molybdenum-tungsten composite oxide modified boron nitride powder and zirconium-hafnium silicon oxide composite microspheres, address the core technical problems of insufficient gripping force, short lifespan, and unstable precision caused by high-temperature performance degradation in traditional rollers by enhancing interfacial bonding, strengthening the matrix, and improving high-temperature stability.

[0047] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a composite coated diamond roller, characterized in that the steps include... include: S1. By weight, 35-45 parts of synthetic diamond micro powder and binder powder are mixed to obtain a mixture; the binder powder comprises 20-30 parts of electrolytic copper powder, 15-25 parts of carbonyl nickel powder, 8-12 parts of cobalt powder, 1.5-3.0 parts of molybdenum-tungsten composite oxide modified boron nitride powder and 2.0-4.0 parts of zirconium-hafnium silicon oxide composite microspheres; the mixture is placed in a mixer and stirred to obtain a mixed powder; S2. The mixed powder is loaded into the annular groove of the pre-formed steel roller matrix, and vacuumed to ≤10Pa. It is then cold isostatically pressed to obtain a compact. The compact is placed in a vacuum sintering furnace, heated to 915-925℃ and held, then heated to 1045-1055℃ and held, and cooled to room temperature with the furnace. The compact is then ground on the outer cylindrical surface and the cutting edge is trimmed.

2. The method for preparing the composite coated diamond roller according to claim 1, characterized in that, In step S1, the stirring time is 12-14 hours.

3. The method for preparing the composite coated diamond roller according to claim 1, characterized in that, In step S2, the temperature is raised to 1045-1055℃ and held for 60-80 minutes.

4. The method for preparing the composite coated diamond roller according to claim 1, characterized in that, The preparation method of the molybdenum-tungsten composite oxide modified boron nitride powder includes: A1. Add hexagonal boron nitride powder to deionized water and disperse by ultrasonication; then add ammonium heptamolybdate and sodium tungstate and stir; adjust the pH to 9.4-9.6 with concentrated ammonia, raise the temperature to 84-86℃ and stir continuously; add boric acid dropwise and continue the reaction to obtain the reaction mixture; A2. Cool the reaction mixture to room temperature, centrifuge to collect the precipitate, wash the precipitate with ethanol and deionized water in sequence, and dry it under vacuum at 58-62℃ to obtain a solid product; place the solid product in a tube furnace, heat it to 895-905℃ under a nitrogen atmosphere, keep it at that temperature, cool it naturally, grind and sieve it.

5. The method for preparing the composite coated diamond roller according to claim 4, characterized in that, In step A1, the reaction continues for 2-4 hours.

6. The method for preparing the composite coated diamond roller according to claim 4, characterized in that, In step A2, the temperature is raised to 895-905℃ and held for 2-4 hours.

7. The method for preparing the composite coated diamond roller according to claim 1, characterized in that, The preparation method of the zirconium-hafnium silicon oxide composite microspheres includes: B1. Dissolve tetraethyl orthosilicate in anhydrous ethanol, add deionized water and concentrated hydrochloric acid, stir at room temperature to obtain a sol; dissolve zirconium oxychloride and hafnium chloride together in deionized water, add dropwise to the sol, start shear emulsification to obtain a microemulsion; B2. Add ammonia dropwise to the microemulsion to adjust the pH to 7.8-8.2, and continue stirring; collect the microspheres by centrifugation, wash the microspheres with ethanol, and dry them at 78-82℃ to obtain the dried product; place the dried product in a muffle furnace, heat it to 745-755℃ in air atmosphere, hold it at that temperature, then heat it to 1095-1105℃ and hold it at that temperature, and then let it cool naturally.

8. The method for preparing the composite coated diamond roller according to claim 7, characterized in that, In step B1, the shear emulsification is initiated for 5-10 minutes.

9. The method for preparing the composite coated diamond roller according to claim 7, characterized in that, In step B2, the temperature is raised to 745-755℃ and held for 3-4 hours.

10. A composite-coated diamond roller, characterized in that, The composite-coated diamond roller is prepared by the method described in any one of claims 1-9.

Images