Alkali-free low-temperature sintered glass ceramic binding agent as well as preparation method and application thereof

Abstract

The invention relates to a preparation method of an alkali-free low-temperature sintered glass ceramic binding agent. The preparation method comprises the following steps: 1) respectively carrying out ball-milling mixing on a fluxing component, a nucleating component and a high-temperature stable component; 2) preparing a melt, and adding a fluxing component at 1000 DEG C to form a melting system; adding a nucleation component at 1250 DEG C, and inducing the formation of a crystal nucleus by using the stability of the nucleation component at a high temperature; adding the high-temperature stable component at the temperature of 1400 DEG C; 3) carrying out quenching water quenching on the melt, drying, and crushing to obtain crude powder; and 4) refining the rough powder until D90 is less than or equal to 0.3 m to obtain the alkali-free low-temperature sintered glass ceramic binding agent. The water resistance and acid resistance of the diamond grinding wheel are improved through an alkali-free metal formula, the melting temperature of the binding agent is smaller than or equal to 750 DEG C, and the thermal expansion coefficient of the binding agent is matched with that of diamond; the microhardness and the breaking strength are improved through effective devitrification, and the service life of the diamond grinding wheel is prolonged by more than or equal to 30%.

Description

Technical Field

[0001] This invention relates to alkali-free low-temperature sintering microcrystalline glass binders, their preparation methods, and applications, belonging to the field of diamond binder technology. Background Technology

[0002] Currently, diamond grinding wheel bonding systems mainly include resin, metal, and ceramic bonds. While resin bonds offer low preparation temperatures and good self-sharpening properties, they suffer from low strength, poor heat resistance, and susceptibility to deformation. Metal bonds offer high strength and good wear resistance, but typically require high-temperature sintering, and the grinding wheels have high hardness, making dressing difficult. Traditional ceramic bonds (such as silicates and borosilicates) possess high strength and heat resistance, but often suffer from high brittleness, insufficient toughness, poor wettability with diamond, and insufficient abrasive grain retention. These factors limit the application of grinding wheels in high-efficiency, high-precision, and difficult-to-machine material grinding.

[0003] By designing and preparing multi-component synergistically optimized microcrystalline glass binders, materials can possess high strength, high toughness, excellent thermal stability, and good interfacial bonding performance with diamond. Employing a glass-ceramic design strategy, the softening point, coefficient of thermal expansion of the glass phase, and the type, quantity, morphology, and distribution of precipitated crystalline phases can be precisely controlled. This design not only effectively enhances the chemical bonding and mechanical holding force of the binder to diamond abrasive grains but also optimizes its sintering behavior and reduces the densification temperature, providing a new approach for controlling the interfacial bonding strength and service performance of high-performance diamond grinding wheels. Because microcrystalline glass binders can achieve the composite of the glass phase and various functional crystalline phases through component design, and the strengthening and toughening effect of precipitated crystalline phases (such as high-hardness β-spodumene, high-toughness enstatite, and specific oxides with good thermal compatibility with diamond), this binder system maintains excellent mechanical properties and structural stability even under harsh conditions such as high grinding temperatures and high impact loads.

[0004] Traditional diamond grinding wheels use microcrystalline glass binders that require high-temperature sintering (>900℃), resulting in severe thermal damage to the diamond, high energy consumption, and a mismatch between the binder's and diamond's coefficients of thermal expansion (CTE), which easily leads to cracking. While existing technologies can lower the melting temperature by adding flux, this weakens the binder's strength and heat resistance. Summary of the Invention

[0005] This invention achieves efficient low-temperature (≤750℃) preparation of alkali-free microcrystalline glass binders through a synergistic process of "gradient melting-pre-calcination wet milling-high-energy activation". The specific scheme is as follows: A method for preparing an alkali-free low-temperature sintering microcrystalline glass binder includes the following steps: 1) The fluxing component, nucleating component, and high-temperature stabilizing component were ball-milled and mixed separately; the fluxing component was B2O3, P2O5, and Bi2O3; the nucleating component was ZrO2, TiO2, V2O5, and CeO2; and the high-temperature stabilizing component was SiO2, Al2O3, CaO, and ZnO. 2) Prepare the melt by adding fluxing components at 1000℃ to form a molten system; add nucleating components at 1250℃ to induce crystal nuclei formation by utilizing their stability at high temperatures; and add high-temperature stabilizing components at 1400℃. 3) The melt is rapidly cooled and quenched in water, dried, and pulverized to obtain coarse powder; 4) Refine the coarse powder to D 90 ≤0.3 µm, yielding an alkali-free low-temperature sintering microcrystalline glass binder.

[0006] This invention achieves low-temperature, high-efficiency sintering and controllable crystallization of the binder by optimizing the composition and heat treatment process. The resulting uniform, fine, and interwoven crystalline network structure, especially the needle-like crystalline phase with a high aspect ratio, significantly improves the toughness, strength, and abrasive grain holding power of the binder, thereby greatly enhancing the overall grinding performance and service life of the grinding wheel.

[0007] Preferably, in step 1), the mass ratio of each component is: CaO 5%–15%, SiO2 40%–55%, Al2O3 5%–15%, B2O3 5%–10%, P2O5 5%–10%, Bi2O3 5%–8%, ZnO 5%–10%, TiO2 2%–5%, ZrO2 1%–5%, CeO2 1%–3%, Cr2O3 1%–3%, V2O5 1%–3%.

[0008] More preferably, the molar ratio of CaO to SiO2 is 1.2:1.

[0009] More preferably, in step 1), the mass ratio of each component is: CaO 15%, SiO2 40%, Al2O3 7%, B2O3 6%, P2O5 10%, Bi2O3 5%, ZnO 10%, TiO2 2%, ZrO2 1%, CeO2 1%, Cr2O3 1%, V2O5 2%.

[0010] Preferably, in step 4), the coarse powder is first pre-calcined at 350°C and then refined by wet grinding.

[0011] This invention also claims protection for the alkali-free low-temperature sintering microcrystalline glass binder prepared by the above preparation method.

[0012] The alkali-free low-temperature sintering microcrystalline glass binder of the present invention is suitable for preparing diamond grinding wheels, with a sintering temperature ≤750℃.

[0013] The diamond grinding wheel prepared by the alkali-free low-temperature sintered microcrystalline glass binder of the present invention is particularly suitable for high-precision, low-damage grinding of difficult-to-machine materials such as semiconductor silicon wafers, aerospace high-temperature alloys, and optical glass.

[0014] This invention achieves efficient low-temperature (≤750℃) preparation of microcrystalline glass binders without alkali through a synergistic process of "gradient melting-pre-calcination wet milling-high-energy activation". Its innovation lies in: (1) The low-temperature and efficient preparation of alkali-free microcrystalline glass binder is achieved by adopting a one-step molding process of "gradient melting-pre-sintering and wet grinding-high-energy activation": it avoids the oxidation / graphitization of diamond caused by traditional ≥800 ℃ sintering, and simultaneously completes densification and crystal phase regulation through in-situ crystallization of melt + high-energy bond breaking, which significantly simplifies the process and improves the structural stability.

[0015] (2) The composition design focuses on the "alkali-free + high borosilicate" system (SiO2-B2O3-P2O5-Bi2O3-V2O5), with a basic glass phase CTE of 4.2×10. -6 / K, with diamond (1×10 -6 / K) High matching; the functional crystal phase selection is wollastonite + magnesium aluminum spinel, and the directional precipitation of needle-shaped wollastonite (aspect ratio > 15) is precisely induced by the CaO / Al2O3 molar ratio; V2O5 and Bi2O3 are introduced as double fluxes, with an ionic radius difference ≤ 12% and an electronegativity gradient distribution to achieve hierarchical crystallization; the multi-component system promotes crystallization and forms a submicron uniform crystal phase network.

[0016] (3) Compared with traditional alkali-free ceramic binders, the performance has been greatly improved: the melting temperature is reduced by more than 200 ℃ (≤800 ℃), the sintering time is shortened by 60%, the energy consumption is reduced by 35%, the carbon emission is reduced by 30%, the flexural strength is improved, and the coefficient of thermal expansion is reduced.

[0017] (4) Innovative process achieves precise structural control: Stepwise melting effectively controls the melting process, ensuring that each component plays its role at an appropriate temperature, thereby achieving efficient preparation of glass-ceramic binders; the synergistic effect of pre-firing and wet milling, with pre-firing at 300-400℃ introducing microcracks and wet milling refining to D 90 ≤0.3 µm, refining efficiency improved by 40%; high-energy ball milling technology is adopted to increase specific surface area and thus improve reaction activity, and sintering activation energy is reduced by 30%.

[0018] This invention improves the water and acid resistance of diamond grinding wheels through an alkali-free metal formulation, and achieves a binder melting temperature ≤750℃ with a binder thermal expansion coefficient that matches that of diamond. Effective crystallization enhances microhardness and flexural strength, thereby extending the service life of diamond grinding wheels by ≥30%. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the preparation process of the alkali-free microcrystalline glass binder in this invention.

[0020] Figure 2 The XRD patterns are those of the binder obtained in Example 1 and the microcrystalline glass binder sintered at 750°C.

[0021] Figure 3 The SEM image of the binder obtained in Example 1 is magnified 2000 times.

[0022] Figure 4 The SEM image of the binder obtained in Example 1 is magnified 5000 times. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0024] The present invention employs, such as Figure 1 The process flow shown is used to prepare the microcrystalline glass binder: (1) Alkali-free formulation and performance-oriented design: Through thermodynamic calculations and phase diagram analysis, it was determined that the binder components must meet the alkali-free low-temperature eutectic characteristics. The CaO-SiO2-Al2O3-B2O3-P2O5-Bi2O3 multi-component fluxing system was preferentially selected, and TiO2 / ZrO2 / CeO2 / V2O5 multi-component nucleating agent was used to induce the precipitation of high-hardness needle-like wollastonite (CaSiO3) and anorthite (CaAl2Si2O8). The CaO / Al2O3 ratio was adjusted to approximately 1.2 (mol) to precisely reduce the CTE to 4.2 × 10⁻⁶. -6 / K, with diamond (1.0×10 -6 / K) Highly matched. Composition range (wt%): CaO 5%–15%, SiO2 40%–55%, Al2O3 5%–15%, B2O3 5%–10%, P2O5 5%–10%, Bi2O3 5%–8%, ZnO 5%–10%, TiO2 2%–5%, ZrO2 1%–5%, CeO2 1%–3%, Cr2O3 1%–3%, V2O5 1%–3%, completely free of alkali metal oxides.

[0025] Stepwise melting-water quenching process: ① Raw material pretreatment: Accurately weigh SiO2, Al2O3, B2O3, P2O5, Bi2O3, V2O5, ZnO, TiO2, ZrO2, CeO2, and Cr2O3 (purity >99.5%) according to the alkali-free formula; ball milling and mixing: ball-to-material ratio 3:1, anhydrous ethanol medium, 300 rpm × 4 h. ② Stepwise melting: In the 1400℃ melting process, the feeding sequence of stepwise melting is as follows: At 1000℃, add fluxing components such as B2O3, P2O5, Bi2O3, and V2O5. These components can melt preferentially, reduce the viscosity of the system, and prepare for the subsequent melting process. At 1250℃, add ZrO2 + TiO2 as a nucleating agent, utilizing its stability at high temperatures to induce crystal nucleus formation, providing a foundation for the subsequent growth of crystal phases. The remaining raw materials, such as SiO2 and Al2O3, which are high-temperature stable components, are added at 1400℃ for final melting. These raw materials completely melt at high temperature and thoroughly mix with the previous melt to form a homogeneous glassy film. (2) Glass melt. This stepwise feeding method can effectively control the melting process and ensure that each component plays its role at an appropriate temperature, thereby achieving efficient preparation of glass-ceramic binders. ③ Melt water quenching treatment: The melt is quickly poured into deionized water for rapid cooling and quenching; then dried at 60-80 ℃ for 6-8 h, pulverized with a pulverizer and passed through a 200-mesh sieve for later use.

[0026] (3) Pre-calcination and wet milling - high-energy activation: In the powder treatment stage, the powder is first pre-calcined at 350 ℃ for 1.5 h, and then wet-milled with agate balls and deionized water (200 rpm for 60 min) to process the D 90 The material was refined to ≤0.3 µm, with a refining efficiency 40% higher than that of direct wet milling. Then, it was further refined by high-energy ball milling (800 rpm, 3:1 ratio of zirconia balls, 45 min) to increase the specific surface area and thus improve the reaction activity, thereby reducing the sintering activation energy by 30%.

[0027] (4) Binder molding and sintering: 5% PVA and 30MPa dry pressing are added to the molding section, and then sintered once at 750 ℃×50 min (heating rate: 10-20 ℃ / min). No secondary crystallization or external seed crystals are required throughout the process.

[0028] (5) Testing and characterization: XRD test: Take an appropriate amount of sintered sample, grind it into powder to ensure that the powder particles are fine and uniform, and use an X-ray diffractometer with a scanning angle of 10°-90°, a step size of 0.02°, and a scanning speed of 2° / min for testing; SEM test: Take a small piece from the sintered sample, grind and polish the surface to make it smooth and flat, spray gold for 90s, use a scanning electron microscope, set the accelerating voltage to 10-20 kV, observe from low magnification to high magnification step by step, and use CTE test to detect whether the thermal expansion coefficient of the microcrystalline glass matches that of diamond; use a Vickers hardness tester to measure the hardness of the binder, and use a universal testing machine to test its flexural strength.

[0029] The following examples are microcrystalline glass binders prepared based on the alkali-free metal formulation design and the "stepwise melting-pre-calcination wet grinding-high-energy activation-low-temperature sintering" process of this patent.

[0030] Example 1 According to the formula design: The raw materials are weighed according to the following mass ratios: CaO 15%, SiO2 40%, Al2O3 7%, B2O3 6%, P2O5 10%, Bi2O3 5%, ZnO 10%, TiO2 2%, ZrO2 1%, CeO2 1%, Cr2O3 1%, and V2O5 2%. The raw materials are then placed in a planetary ball mill for ball milling at a ball-to-material ratio of 3:1. The first set of zirconia ceramic balls comprises: 10-30% 10mm zirconia ceramic balls, 20-30% 8mm zirconia ceramic balls, and 50-70% 5mm zirconia ceramic balls. The second set of ball-to-material balls has a ratio of 2:2. The ratio of 0.5:1, the second zirconia ceramic balls comprises: 10-20% 5mm zirconia ceramic balls, 10-30% 3mm zirconia ceramic balls, and 60-80% 1mm zirconia ceramic balls, milled at 200 rpm for 2 hours; after ball milling, the material is dried, and then placed in a high-temperature sintering furnace for stepwise melting. The feeding sequence for stepwise melting is as follows: at 1000℃, 6% B2O3, 10% P2O5, and 5% Bi2O3 fluxing agents are added. These components can preferentially melt, reduce the viscosity of the system, and prepare for the subsequent melting process. At 1250℃, 1% ZrO2, 2% TiO2, 2% V2O5, and 1% CeO2 are added as nucleating agents. Their stability at high temperatures induces crystal nucleus formation, providing a foundation for the subsequent growth of crystal phases. The remaining raw materials (40% SiO2, 37% Al2O3, 15% CaO, and 10% ZnO) were added at 1400℃ for final melting. The molten sample was then subjected to water quenching to obtain a glass block. The block was pulverized using a pulverizer and passed through a 200-mesh sieve. The resulting powder was pre-calcined at 350℃ for 1.5 h and then wet-milled at 200 rpm for 1 h. The ball-milled raw material was then further ball-milled in a high-energy ball mill at 800 rpm for 45 min. After ball milling, the material was dried at 80℃. A certain amount of the pulverized raw material was taken, and 5% PVA solution was added as a binder. The mixture was placed in a circular mold with a diameter of 30 mm and dry-pressed under a pressure of 30 MPa. After holding the pressure for 30 s, the molded sample was removed. The dry-pressed sample was placed in an alumina crucible, and the sintering temperature was set at 750℃ at a rate of 10℃ / min. When the temperature reached near the sintering temperature, the sample was held for 50 min.

[0031] Result: As Figure 2 As shown, the XRD pattern of the glass powder obtained by melt water quenching exhibits typical amorphous peaks. The XRD pattern of the sintered microcrystalline glass binder shows multiple obvious diffraction peaks, corresponding to wollastonite (CaSiO3) and magnesium aluminum spinel (MgAl2O4) crystalline phases. This indicates that the expected high-hardness crystalline phase was successfully induced and well-developed under the stepwise melting-pre-calcination wet grinding-high-energy activation process. Figure 3 and Figure 4 SEM images revealed a large number of microcrystals, approximately 0.5-2 µm in size, precipitated on the sample surface. These microcrystals were needle-like and columnar, interwoven in a network structure. This structure significantly improves the various properties of the binder. Flexural strength: 160 MPa, Vickers hardness: 7.5 GPa, fracture toughness: 4.2 MPa·m¹ / ², coefficient of thermal expansion: 4.2 × 10⁻⁶. -6 / K.

[0032] Example 2 The formulation used in this embodiment is CaO 5%, SiO2 55%, Al2O3 5%, B2O3 5%, P2O5 5%, Bi2O3 7%, ZnO 5%, TiO2 5%, ZrO2 5%, CeO2 1%, Cr2O3 1%, V2O5 1%. The remaining process parameters are the same as in Example 1. Results: density 98.7%, grain size approximately 180 nm, flexural strength 148 MPa, Vickers hardness 7.8 GPa, fracture toughness 3.1 MPa·m¹ / ², and coefficient of thermal expansion 3.9 × 10⁻⁶. -6 / K.

[0033] Example 3 The formulation used in this embodiment is CaO 5%, SiO2 40%, Al2O3 15%, B2O3 10%, P2O 55%, Bi2O3 8%, ZnO 5%, TiO2 2%, ZrO 2 1%, CeO 2 3%, Cr2O 3 3%, V2O 5 3%. The remaining process parameters are the same as in Example 1. Results: density 98.4%, grain size approximately 1-3µm, flexural strength 156 MPa, Vickers hardness 7.5 GPa, fracture toughness 3.5 MPa·m¹ / ², and coefficient of thermal expansion 4.3 × 10⁻⁶. -6 / K.

[0034] Compare with Example 1 The formulation adopted a traditional alkali metal-containing formula: Li₂O 10%, CaO 10%, SiO₂ 45%, Al₂O₃ 7%, B₂O₃ 10%, P₂O 5 4%, TiO₂ 3%, ZrO₂ 2%, Cr₂O 3 4%. The raw materials were weighed, and the preparation process and other parameters were the same as in Example 1. Results: Performance indicators decreased somewhat; density was 98.5%, grain size was approximately 1-3 µm, flexural strength was 135 MPa, Vickers hardness was 6.8 GPa, fracture toughness was 3.2 MPa·m¹ / ², and coefficient of thermal expansion was 5.8 × 10⁻⁶. -6 / K.

[0035] Compare with Example 2 The formulation is the same as in Example 1. The preparation process adopts the traditional melting process, which is a constant temperature melting at 1500 ℃ for 1 h. Pre-firing-wet milling and high-energy activation are not used. The sintering parameters remain unchanged at 750 ℃ ​​for 50 min.

[0036] After sintering, the density was 98.1%, and the properties were lower than those of Example 1. The flexural strength was 120 MPa, the density was 96.8%, and the CTE was 4.8 × 10⁻⁶. -6 / K, Vickers hardness 6.2 GPa, fracture toughness 2.8 MPa·m¹ / ², coefficient of thermal expansion 6.5×10 -6 / K.

[0037] This invention, through the design of an alkali-free metal formulation and improvements to the microcrystalline glass preparation process, uses pure oxides as raw materials and employs a stepwise melting + pre-calcination wet grinding + high-energy ball milling activation process to synthesize an alkali-free microcrystalline glass binder sample for diamond grinding wheels at low temperatures. This effectively shortens the melting time and lowers the sintering temperature to 750℃. The alkali-free microcrystalline glass binder effectively improves the water and acid resistance of diamond grinding wheels. The rational combination of fluxing components such as B2O3 and P2O5 achieves a high degree of matching with the coefficient of thermal expansion (CTE) of diamond, enhancing the dimensional and thermal stability of the grinding wheel during grinding. The combination of stepwise melting, pre-calcination wet grinding, high-energy ball milling activation, and low-temperature crystallization effectively refines the grains and optimizes the crystal phase composition, thereby significantly improving mechanical properties such as flexural strength. The lower sintering temperature and optimized process effectively reduce thermal damage to diamond abrasive grains at high temperatures, reduce graphitization rate, thereby extending the service life of the grinding wheel and improving grinding quality. This innovative approach overcomes the limitations of traditional processes and significantly reduces energy consumption.

Claims

1. A method for preparing an alkali-free low-temperature sintered microcrystalline glass bond, characterized by, The method comprises the following steps: 1) separately ball-milling the fluxing component, the nucleating component and the high-temperature stabilizing component; the fluxing component is B2O3, P2O5 and Bi2O3; the nucleating component is ZrO2, TiO2, V2O5 and CeO2; the high-temperature stabilizing component is SiO2, Al2O3, CaO and ZnO; 2) preparing a melt, adding the fluxing component to form a molten system at 1000℃; adding the nucleating component at 1250℃ to induce the formation of crystal nucleus by its stability at high temperature; adding the high-temperature stabilizing component at 1400℃; 3) quenching the melt by water, drying and crushing to obtain a crude powder; 4) Coarse powder is refined to D 90 ≤ 0.3 µm, resulting in an alkali-free low-temperature sintered glass-ceramic bond.

2. The method for preparing the alkali-free low-temperature sintering microcrystalline glass binder according to claim 1, characterized in that, In step 1), the mass ratio of each component is: CaO 5%-15%, SiO2 40%-55%, Al2O3 5%-15%, B2O3 5%-10%, P2O5 5%-10%, Bi2O3 5%-8%, ZnO 5%-10%, TiO2 2%-5%, ZrO2 1%-5%, CeO2 1%-3%, Cr2O3 1%-3%, V2O5 1%-3%.

3. The method for preparing the alkali-free low-temperature sintering microcrystalline glass binder according to claim 2, characterized in that, The molar ratio of CaO to SiO2 is 1.2:

1.

4. The method for preparing the alkali-free low-temperature sintering microcrystalline glass binder according to claim 1, characterized in that, In step 1), the mass ratio of each component is: CaO 15%, SiO2 40%, Al2O3 7%, B2O3 6%, P2O5 10%, Bi2O3 5%, ZnO 10%, TiO2 2%, ZrO2 1%, CeO2 1%, Cr2O3 1%, V2O5 2%.

5. The method for preparing the alkali-free low-temperature sintering microcrystalline glass binder according to claim 1, characterized in that, In step 4), the crude powder is first pre-fired at 350℃, and then refined by wet milling.

6. The alkali-free low-temperature sintering microcrystalline glass bond prepared by the method according to any one of claims 1-5.

7. The use of the alkali-free low temperature sintered glass-ceramic bond according to claim 6, characterized in that, For preparing a diamond grinding wheel.

8. The use of the alkali-free, low-temperature sintered microcrystalline glass bond according to claim 7, characterized in that, For grinding processing of semiconductor silicon wafers, aerospace high-temperature alloys and optical glass. For preparing a diamond grinding wheel. For grinding processing of semiconductor silicon wafers, aerospace high-temperature alloys and optical glass.

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