A ceramic guide rail for ultra-precision machining and ultra-precision measuring instruments and its preparation method

Abstract

This invention discloses a ceramic guide rail for ultraprecision machining and ultraprecision measuring instruments, and its preparation method. The raw materials include: 40-58% nano-α-Al2O3; 10-15% titanium carbide; 5-8% boron nitride; 5-10% Y2O3-MgO composite; 3-5% zirconium oxide; 1-2% La2O3; 0.5-1.5% graphene; and 2-5% nano-CeO2@Al2O3 core-shell particles. The ceramic guide rail exhibits excellent wear resistance, dimensional stability, and thermomechanical properties, making it particularly suitable for use as guide components in ultraprecision machining equipment and measuring instruments.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic materials, and in particular to a ceramic guide rail for ultra-precision machining and ultra-precision measuring instruments and a preparation method thereof. Background Art

[0002] Modern ultra-precision machining and measurement technologies place stringent demands on the performance of key moving components. Ceramic guides are gradually replacing traditional metal guides due to their superior hardness, wear resistance, low thermal expansion coefficient, and good chemical stability. However, existing ceramic guide materials still face challenges in the extreme operating conditions of high-precision, long-life operation. These challenges include insufficient fracture toughness under complex stresses, precision degradation due to friction and wear, and difficulty maintaining long-term dimensional stability in high-temperature environments. These issues hinder further improvement in the ultimate precision of instruments and equipment.

[0003] To overcome these bottlenecks, researchers have tried a variety of approaches, including introducing various reinforcing phases, optimizing sintering aid systems, and exploring new composite structures. A common strategy is to add hard phases to the alumina matrix or modify it with rare earth oxides to improve the material's comprehensive mechanical properties and high-temperature performance. Despite this, how to achieve fine-tuning of the material's internal structure, effectively improving toughness while ensuring high hardness, and ensuring that the material maintains excellent dimensional stability and low friction properties during sintering and service remains a key technical challenge that needs to be solved.

[0004] Therefore, developing a new type of high-performance ceramic guide rail material through innovative component design and advanced preparation technology, especially introducing a nano-reinforced phase with a specific structure and an effective composite sintering aid system to achieve synergistic optimization of material strength, toughness, wear resistance and thermal stability, has important engineering application value and scientific significance for meeting the stringent requirements of the next generation of ultra-precision equipment for near-zero wear of moving parts and nanometer-level precision maintenance. Summary of the Invention

[0005] The purpose of the present invention is to provide a ceramic guide rail for ultra-precision machining and ultra-precision measuring instruments and a preparation method thereof, which solves the problems that traditional ceramic guide rails are brittle, have insufficient wear resistance, have poor dimensional stability at high temperatures, and are difficult to meet the stringent requirements of ultra-precision instruments for long life and nanometer-level precision.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0007] A ceramic guide rail, the raw materials of which include, by mass percentage:

[0008] Nano-α-Al2O3: 40-58%;

[0009] Titanium carbide: 10-15%;

[0010] Boron nitride: 5-8%;

[0011] Y2O3-MgO complex: 5-10%;

[0012] Zirconia: 3-5%;

[0013] La2O3: 1-2%;

[0014] Graphene: 0.5-1.5%;

[0015] Nano CeO2@Al2O3 core-shell particles: 2-5%;

[0016] The preparation method of the nano CeO2@Al2O3 core-shell particles includes: dissolving Ce(NO3)3·6H2O in deionized water to prepare a cerium salt solution, adding ammonia water to adjust the pH to 8-9 to generate Ce(OH)3 precipitate, centrifuging and washing, and dispersing the precipitate into ethanol to form a Ce(OH)3 sol; then dissolving Al(OCH2CH3)3 in anhydrous ethanol, adding the Ce(OH)3 sol dropwise according to an Al / Ce molar ratio of 2:1-4:1, and obtaining a gel at a constant temperature of 60-80°C; drying the obtained gel at 100°C, and then calcining it at 1200°C in a muffle furnace.

[0017] In the present invention, during the sintering and service process, each component achieves synergistic performance through multi-stage reactions: the Y2O3-MgO-La2O3 composite forms a low eutectic liquid phase at 1650°C, wets the nano-α-Al2O3 matrix and drives the particle rearrangement and densification, while titanium carbide and boron nitride react in situ (TiC+2BN→TiB2+C+N2↑), and the generated TiB2 nanocrystals (50-80nm) pin the grain boundaries to inhibit grain growth, while free carbon and residual h-BN cooperate with graphene to form a gradient lubricating film at the friction interface; zirconium oxide expands through t→m phase transition to absorb crack energy, and La2O3 purifies the grain boundary glass phase to generate high melting point La2Si2O7 (1950°C), which reacts with Y3Al5O 12 / MgAl2O4 grain boundary phases jointly improve high temperature stability; nano CeO2@Al2O3 core-shell particles play a dual toughening mechanism - the valence state transformation of the core CeO2 (Ce 3+ / Ce 4+ ) induces local compressive stress, and the shell Al2O3 induces crack deflection while avoiding adverse reactions between CeO2 and the matrix.

[0018] According to a preferred embodiment of the present invention, the nano α-Al2O3 is purchased from Zhejiang Yamei Nano Technology Co., Ltd.

[0019] According to a preferred embodiment of the present invention, the titanium carbide is purchased from Beijing Xingrongyuan Technology Co., Ltd.

[0020] According to a preferred embodiment of the present invention, the boron nitride is purchased from Qinghe County Yaoxie Metal Materials Co., Ltd.

[0021] According to a preferred embodiment of the present invention, the zirconium oxide is purchased from Shandong Desheng New Materials Co., Ltd.

[0022] According to a preferred embodiment of the present invention, the La2O3 is purchased from Ganzhou Jiaxing Rare Earth New Materials Co., Ltd.

[0023] According to a preferred embodiment of the present invention, the graphene is purchased from Suzhou Carbon Graphene Technology Co., Ltd.

[0024] According to a preferred embodiment of the present invention, the Ce(NO3)3·6H2O is purchased from Shanghai Yanbei New Material Technology Co., Ltd.

[0025] According to a preferred embodiment of the present invention, the deionized water is purchased from Guangzhou Hongwei Water Treatment Equipment Co., Ltd.

[0026] According to a preferred embodiment of the present invention, the Al(OCH2CH3)3 is purchased from Qinghe County Fengye Metal Materials Co., Ltd.

[0027] According to a preferred embodiment of the present invention, the anhydrous ethanol is purchased from Shandong Juxing Chemical Co., Ltd.

[0028] According to a preferred embodiment of the present invention, the muffle furnace is purchased from Nanjing Kejie Testing Technology Development Co., Ltd.

[0029] In the present invention, nano-α-Al2O3 is used as the core skeleton of the ceramic matrix, and densification is achieved through the liquid phase sintering mechanism during high temperature sintering at 1700℃: the Y2O3-MgO-La2O3 composite additive forms a low eutectic liquid phase (melting point is about 1650℃), which wets the surface of Al2O3 particles and drives the particles to rearrange through capillary force; at the same time, Al 3+ Diffusion and mass transfer in the liquid phase fill micropores and promote grain boundary migration. Its nanometer size provides a high specific surface area, and the surface energy drives the Ostwald ripening process, allowing the grains to grow uniformly to the submicron level, avoiding strength degradation caused by abnormal growth.

[0030] According to a preferred embodiment of the present invention, the concentration of the cerium salt solution is 0.1-0.3 mol / L, the stirring time is 6-12 hours at a constant temperature of 60-80°C, the obtained gel is dried at 100°C for 12 hours, and placed in a muffle furnace for calcination at 1200°C for 2-4 hours; the heating rate is 5°C / min.

[0031] In the present invention, titanium carbide and boron nitride react in situ in a nitrogen atmosphere at 1650-1780°C: TiC + 2BN → TiB2 + C + N2↑ The generated TiB2 nanocrystals are dispersed in the matrix, suppressing the excessive growth of Al2O3 grains by pinning the grain boundaries; free carbon and residual h-BN form a double lubrication transfer film at the friction interface: the shear strength between the h-BN basal layers is only 0.02GPa, and the graphene sheets provide ultra-low friction, synergistically reducing the wear rate.

[0032] According to a preferred embodiment of the present invention, the core diameter of the nano-CeO2@Al2O3 core-shell particles is 50-100 nm, and the shell thickness is 5-10 nm.

[0033] According to a preferred embodiment of the present invention, the preparation method of the Y2O3-MgO composite includes: mixing Y2O3 and MgO nanopowders with magnesium nitrate and yttrium nitrate salt solutions, and then uniformly dispersing them by ball milling, followed by spray drying or freeze drying to form a precursor, and calcining at 800-1000°C for 2-4 hours.

[0034] According to a preferred embodiment of the present invention, the Y2O3 is purchased from Ganzhou Jiaxing Rare Earth New Materials Co., Ltd.

[0035] According to a preferred embodiment of the present invention, the MgO nanopowder is purchased from Hangzhou Jikang New Materials Co., Ltd.

[0036] According to a preferred embodiment of the present invention, the magnesium nitrate is purchased from Shanxi Jinlan Chemical Co., Ltd.

[0037] According to a preferred embodiment of the present invention, the yttrium nitrate salt solution is purchased from Shandong Desheng New Materials Co., Ltd.

[0038] According to a preferred embodiment of the present invention, the ball milling speed is 300-500 r / min, and the time is 3-6 hours; the grain size of the Y2O3-MgO composite is less than 150 nm.

[0039] In the present invention, the Y2O3-MgO composite undergoes a grain boundary reaction during sintering: 3Y2O3+5Al2O3→2Y3Al5O 12 (YAG) (melting point 1940℃) MgO+Al2O3→MgAl2O4 spinel (melting point 2135℃) Y 3+ With Mg 2+Ions selectively segregate to Al2O3 grain boundaries, consuming the SiO2 / CaO impurity glass phase and raising the grain boundary phase melting point from 900°C to >1600°C. Their nanoscale size limits the matrix grain size to <0.5μm through a pinning effect (resistance F=3γ·f / 2r, where γ is the grain boundary energy and f is the volume fraction), resulting in a hardness of 22.5GPa and improved high-temperature stability of the grain boundaries.

[0040] In the present invention, the zirconia undergoes stress-induced phase transformation (t→m) to absorb the crack propagation energy, while La 3+ Ion-doped zirconia stabilizes the tetragonal phase and expands the phase transformation toughening temperature range (-50-800℃); La2O3 preferentially reacts with SiO2 impurities to form high-melting-point La2Si2O7 (melting point 1950℃), purifying the grain boundaries and inhibiting high-temperature grain boundary creep.

[0041] In the present invention, graphene is distributed along the grain boundaries during the sintering process, and the toughness is improved by bridging cracks through two-dimensional layers (crack expansion requires energy consumption across the graphene layers); during service, a continuous carbon film is formed at the friction interface through interlayer shear slip, reducing the wear rate by 70% (compared with a system without graphene).

[0042] The core CeO2 of the nano CeO2@Al2O3 core-shell particles in the present invention undergoes Ce 3+ / Ce 4+ The valence state transition, accompanied by a 4% volume expansion, offsets the crack opening displacement. The Al2O3 shell forms a coherent interface with the matrix (lattice mismatch <3%), inducing crack deflection. The core-shell structure prevents direct CeO2 contact with the matrix, which can lead to uncontrolled interfacial reactions, improving toughening efficiency by 29% (compared to conventional CeO2).

[0043] The present invention also provides a method for preparing the ceramic guide rail, comprising the following steps:

[0044] S1, pre-dispersing titanium carbide, boron nitride, nano-CeO2@Al2O3 core-shell particles with a small amount of ethanol; adding nano-α-Al2O3, Y2O3-MgO composite, zirconium oxide, and La2O3, wet ball milling with a ball-to-material ratio of 3:1; finally adding graphene, stirring, and drying in an oven to obtain a powder;

[0045] S2, the powder is loaded into the mold and pre-pressed to 50-100 MPa; transferred to the isostatic press and pressurized to 200-300 MPa;

[0046] S3, heating the pressurized powder in step S2 to 1200°C in an inert atmosphere and calcining it, and keeping it warm; switching to a nitrogen atmosphere, heating it to 1650-1780°C and calcining it, and keeping it warm; applying a pressure of 100-150 MPa to obtain a sintered green body; rough grinding the sintered green body with a diamond grinding wheel; fine-machining it with an ultra-precision surface grinder, with a surface roughness Ra ≤ 0.01 μm; and vacuum packaging it after cleaning.

[0047] According to a preferred embodiment of the present invention, in step S1, wet ball milling is performed for 8-12 hours; and stirring is performed for 1-2 hours.

[0048] According to a preferred embodiment of the present invention, in step S2, pre-pressing is performed to 50-100 MPa and holding the pressure for 5 minutes; pressurizing is performed to 200-300 MPa and holding the pressure for 20-30 minutes; and the green body density is ≥85%.

[0049] According to a preferred embodiment of the present invention, in step S3, the temperature is raised to 1200° C. at 5° C. / min and kept at this temperature for 2 hours; the temperature is raised to 1650-1780° C. and kept at this temperature for 1-3 hours.

[0050] The present invention also provides an application of the ceramic guide rail or the ceramic guide rail prepared by the preparation method in ultra-precision machining and ultra-precision measuring instruments.

[0051] The beneficial effects of the present invention are:

[0052] This ceramic guide rail significantly enhances the material's overall performance through a unique multi-component collaborative design and sophisticated fabrication process. The combination of a nano-alumina matrix and a titanium carbide hard phase provides exceptional hardness and rigidity. The introduction of boron nitride and graphene effectively reduces the friction coefficient, imparting self-lubricating properties to the material. The addition of the rare earth oxide lanthanum oxide optimizes the grain boundary structure and enhances high-temperature stability. In particular, the innovative nano-cerium oxide and alumina core-shell particles, with their unique structure, act as stress buffers and crack deflectors within the material, significantly enhancing the ceramic's fracture toughness and overcoming the brittleness of traditional ceramic materials.

[0053] This technical solution demonstrates significant advantages in controlling the material's microstructure and achieving densification. The application of a Y2O3-MgO composite sintering aid, combined with optimized wet ball milling and high-energy isostatic pressing, ensures highly uniform dispersion of the components and a high initial density of the powder. The subsequent staged temperature-controlled calcination combined with hot-pressing effectively inhibits abnormal grain growth and facilitates sintering at near-theoretical density, resulting in a dense microstructure with fine, uniform grains and minimal defects. This lays a solid foundation for the material's high strength, hardness, and excellent dimensional stability.

[0054] The resulting ceramic guideway performs exceptionally well under the demanding conditions required by ultraprecision machining and measuring instruments. Its extremely low surface roughness, excellent wear resistance, and low friction ensure long-term smooth operation and precision retention of the kinematic pair, effectively reducing wear and tear and accuracy degradation. The material's excellent thermal stability and chemical inertness make it resilient to ambient temperature fluctuations and trace amounts of corrosive media. Consequently, this ceramic guideway meets the stringent requirements of modern ultraprecision equipment for near-zero wear of moving parts, nanometer-level repeatability, and an extremely long service life. DETAILED DESCRIPTION

[0055] The following specific implementation methods are only used to further illustrate the present application and should not be understood as limiting the scope of protection of the present application. Technicians in this field may make some non-essential improvements and adjustments to the present application based on the above application content.

[0056] 1. Implementation

[0057] Example 1

[0058] Raw material ratio: nano α-Al2O3 50.0g, titanium carbide 12.0g, boron nitride 6.5g, Y2O3-MgO composite 7.0g, zirconium oxide 4.0g, La2O3 1.5g, graphene 1.0g, nano CeO2@Al2O3 core-shell particles 3.0g.

[0059] Nano-CeO2@Al2O3 core-shell particles were prepared by dissolving 8.68g of Ce(NO3)3·6H2O in 100mL of deionized water to obtain a 0.2mol / L cerium salt solution. The solution was then stirred at 60°C for 8 hours to form a Ce(OH)3 precipitate. The solution was washed three times by centrifugation and then dispersed in 50mL of ethanol to form a sol. 12.24g of Al(OCH2CH3)3 (Al / Ce molar ratio 3:1) was dissolved in 30mL of anhydrous ethanol and the sol was added dropwise. The mixture was reacted at 75°C for 6 hours to form a gel. The particles were then dried in a drying oven at 100°C for 12 hours and calcined in a muffle furnace at 5°C / min to 1200°C for 3 hours to obtain core-shell particles with a core diameter of 80nm and a shell thickness of 8nm.

[0060] Preparation of Y2O3-MgO composite: 5.25 g of Y2O3 nanopowder and 1.75 g of MgO nanopowder were mixed, and magnesium nitrate solution (2.56 g Mg(NO3)2·6H2O / 10 mL water) and yttrium nitrate solution (4.45 g Y(NO3)3·6H2O / 10 mL water) were added. The mixture was ball milled at 400 r / min for 4 h in a planetary ball mill (zirconia grinding balls). After spray drying, it was calcined at 900°C for 3 h to obtain a composite with a grain size of 120 nm.

[0061] Ceramic preparation:

[0062] Stage S1: Titanium carbide, boron nitride, and core-shell particles were ultrasonically pre-dispersed with 20 mL of ethanol for 30 min. The remaining raw materials (except graphene) were added and placed in a planetary ball mill (zirconia grinding balls, ball-to-material ratio of 3:1), and wet-milled at 300 r / min for 10 h. After adding graphene, magnetic stirring was performed for 1.5 h, and the mixed powder was dried in an 80°C oven for 24 h.

[0063] S2 stage: The powder is loaded into a steel mold and pre-pressed to 80 MPa and maintained at a pressure of 5 minutes; the cold isostatic press (QIC-300 model) is pressurized to 250 MPa and maintained at a pressure of 25 minutes. The green body density is measured to be 87%.

[0064] In the S3 stage, the green body was placed in a graphite mold and heated to 1200°C at a rate of 5°C / min under argon protection and kept at that temperature for 2 hours. Then, the nitrogen atmosphere was switched and the temperature was raised to 1700°C at a rate of 3°C / min and kept at that temperature for 2 hours, while an axial pressure of 120 MPa was applied simultaneously. The sintered body was coarsely ground with a diamond grinding wheel (grit size #400) and then fine-machined with a PGM-3H ultra-precision surface grinder to a surface roughness of Ra = 0.008 μm. It was then ultrasonically cleaned with isopropyl alcohol for 30 minutes and vacuum-packed in aluminum plastic.

[0065] Example 2

[0066] Raw materials: 45.0g nano-α-Al2O3, 14.0g titanium carbide, 5.5g boron nitride, 8.0g Y2O3-MgO composite, 3.5g zirconium oxide, 1.8g La2O3, 1.2g graphene, 4.0g nano-CeO2@Al2O3 core-shell particles. The core-shell particle preparation parameters were the same as in Example 1, except that the Y2O3-MgO composite was ball-milled for 5h. The preparation process was the same as in Example 1, except that the sintering stage was held at 1680°C for 2.5h.

[0067] Example 3

[0068] Raw materials: 55.0g nano-α-Al2O3, 10.0g titanium carbide, 7.0g boron nitride, 6.0g Y2O3-MgO composite, 4.5g zirconium oxide, 1.2g La2O3, 0.8g graphene, 2.5g nano-CeO2@Al2O3 core-shell particles. The Al / Ce molar ratio of the core-shell particles was adjusted to 4:1, and the calcination time was 2 hours. The preparation process was the same as in Example 1, with a sintering temperature of 1750°C and a holding time of 1.5 hours.

[0069] Comparative Example 1

[0070] Raw materials: 53.0 g of nano-α-Al2O3, 12.0 g of titanium carbide, 6.5 g of boron nitride, 7.0 g of Y2O3-MgO composite, 4.0 g of zirconium oxide, 1.5 g of La2O3, and 1.0 g of graphene (core-shell particles omitted, nano-α-Al2O3 supplemented). The preparation process is the same as in Example 1.

[0071] Comparative Example 2

[0072] The raw materials were the same as those in Example 1, except that 3.0 g of the core-shell particles were replaced with an equal amount of ordinary nano-CeO2 powder (German Bayer HP30 type, average particle size 80 nm). The preparation process was the same as in Example 1.

[0073] Comparative Example 3

[0074] The raw materials were the same as those in Example 1. In the S3 stage, the hot pressing step was omitted and the product was sintered under normal pressure in a nitrogen atmosphere (1700° C. for 2 h). The rest of the process was the same as in Example 1.

[0075] 2. Performance Testing

[0076] The ceramic guide rails prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests according to the following method:

[0077] Hardness and fracture toughness testing: Testing was performed using a Vickers hardness tester (Model FM-700, Mirai Giken, Japan) in accordance with ASTM C1327 (Vickers hardness of ceramics) and ASTM C1421 (fracture toughness of ceramics). Hardness testing conditions were: a test load of 19.6 N (2 kgf) and a dwell time of 15 seconds. Five test points were evenly selected on each sample surface (with a spacing ≥ 3 times the indentation diagonal), and the arithmetic mean was calculated. Fracture toughness was determined using the indentation method: a crack was generated on the polished surface using a 50 N load. The crack length was measured using a scanning electron microscope (SEM, Hitachi SU8010). Fracture toughness was calculated using the Anstis formula K_(IC)=0.016(E / H)^(1 / 2)·(P / c^(3 / 2)), where E is the elastic modulus (measured by pulse excitation), H is the Vickers hardness, P is the load, and c is the crack length.

[0078] Friction and wear testing was conducted according to ASTM G99 (pin-on-disc wear test method) using a multifunctional tribometer (UMT-5, Bruker, USA). The test parameters included a commercial silicon nitride ceramic ball (6 mm diameter, Ra ≤ 0.02 μm) as the wear object, a normal load of 10 N, a linear sliding velocity of 0.2 m / s, a total sliding distance of 1000 m, an ambient temperature of 25 ± 1°C, and a relative humidity of 45 ± 3%. The specimens were ultrasonically cleaned with acetone for 10 minutes before testing. The wear volume was measured using a white light interferometer profilometer (ContourGT-K, Bruker, USA) to measure the three-dimensional morphology of the wear scar. The wear volume was calculated as V = LA (L = wear scar circumference, A = cross-sectional area), and the wear rate was calculated as I = V / (F·S) (F = load, S = sliding distance).

[0079] Density and thermal expansion coefficient test: Density was determined in accordance with ASTM B962 (density standard for metal powder metallurgy products) using the Archimedean drainage method: the sample was boiled in deionized water for 1 hour to remove pores, and the mass in the saturated water state (m_(sat)) and the mass in suspended water (m_(sus)) were measured using a precision balance (0.1 mg resolution). The dry mass (m_(dry)) was obtained after drying at 110°C for 2 hours. The density ρ = m_(dry)·ρ_water / (m_(sat)-m_(sus)) (ρ_water = 0.998 g / cm 3 The thermal expansion coefficient was determined according to ASTM E831 using a thermomechanical analyzer (TMA 402 F3, NETZSCH, Germany): specimen size Φ5 × 10 mm, test range 30–800 °C, heating rate 5 °C / min, nitrogen protection (50 mL / min), thermal expansion coefficient α = (1 / L_0)·(ΔL / ΔT) (L_0 is the initial length).

[0080] Surface roughness test: Based on the international standard ISO 25178 (surface topography measurement), a white light interferometer 3D surface profiler (ContourGT-K) was used. Test conditions: 50x objective lens, scanning area 0.5×0.5 mm, resolution 0.5 μm, three randomly selected locations on each sample were measured on the machined surface, and the arithmetic average roughness Ra value was taken (evaluation formula Ra=(1 / L)∫_(0) ^ (L)|Z(x)|dx).

[0081] Performance test results:

[0082] Table 1: Performance test results of various embodiments and comparative examples

[0083]

[0084] As can be seen from Table 1, the ceramic guide rail prepared by the present invention overcomes the inherent defects of traditional ceramic guide rails through innovative components and process design: the fracture toughness of Example 1 reaches 8.9±0.3 MPa·m^ (1 / 2) , compared with the comparative example 1 without core-shell particles (5.1±0.2 MPa·m^ (1 / 2) ) increased by 75%, verifying that the nano-CeO2@Al2O3 core-shell particles significantly suppressed brittleness through crack deflection and phase transformation toughening mechanisms; at the same time, the wear rate was reduced to 0.80±0.05×10^ (-7) mm 3 / N·m(Compared with 2.65±0.15×10^ (-7) mm 3 / N·m, a decrease of 70%), which is attributed to the synergistic effect of the self-lubricating effect of graphene and the grain boundary strengthening of the core-shell particles; in terms of high temperature dimensional stability, the thermal expansion coefficient of Example 1 is 6.20±0.08×10^ (-6) / K, much lower than 7.52±0.18×10^ (-6) The Y2O3-MgO-La2O3 composite system purifies grain boundaries and compensates for zirconia phase transformation. The final product has a surface roughness of Ra ≤ 0.008 μm, fully meeting the stringent requirements of ultra-precision instruments for long service life and nanometer-level precision.

[0085] The above-described embodiments merely illustrate several implementations of the present invention. 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 a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A ceramic guide rail, characterized in that: In terms of mass percentage, the raw materials include: Nano-α-Al2O3: 54.2-58%; Titanium carbide: 11.5-15%; Boron nitride: 5-8%; Y2O3-MgO complex: 6.9-10%; Zirconia: 3-5%; La2O3: 1-2%; Graphene: 0.5-1.5%; Nano CeO2@Al2O3 core-shell particles: 2-5%; The preparation method of the nano CeO2@Al2O3 core-shell particles includes: dissolving Ce(NO3)3·6H2O in deionized water to prepare a cerium salt solution, adding ammonia water to adjust the pH to 8-9 to generate Ce(OH)3 precipitate, centrifuging and washing, and dispersing the precipitate into ethanol to form a Ce(OH)3 sol; then dissolving Al(OCH2CH3)3 in anhydrous ethanol, adding the Ce(OH)3 sol dropwise according to an Al / Ce molar ratio of 2:1-4:1, and obtaining a gel at a constant temperature of 60-80°C; drying the obtained gel at 100°C, and then calcining it at 1200°C in a muffle furnace.

2. The ceramic guide rail according to claim 1, characterized in that: The concentration of the cerium salt solution is 0.1-0.3 mol / L, and the stirring time is constant at 60-80°C for 6-12 hours. The obtained gel is dried at 100°C for 12 hours and calcined in a muffle furnace at 1200°C for 2-4 hours; the heating rate is 5°C / min.

3. The ceramic guide rail according to claim 1, characterized in that: The nano CeO2@Al2O3 core-shell particles have a core diameter of 50-100 nm and a shell thickness of 5-10 nm.

4. The ceramic guide rail according to claim 1, characterized in that: The preparation method of the Y2O3-MgO composite comprises: mixing Y2O3 and MgO nanopowders with magnesium nitrate and yttrium nitrate salt solutions, then ball milling to achieve uniform dispersion, then spray drying or freeze drying to form a precursor, and calcining at 800-1000°C for 2-4 hours.

5. The ceramic guide rail according to claim 4, characterized in that: The ball milling speed is 300-500 r / min and the time is 3-6 hours; the grain size of the Y2O3-MgO composite is less than 150 nm.

6. A method for preparing a ceramic guide rail according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, pre-dispersing titanium carbide, boron nitride, nano-CeO2@Al2O3 core-shell particles with a small amount of ethanol; adding nano-α-Al2O3, Y2O3-MgO composite, zirconium oxide, and La2O3, wet ball milling with a ball-to-material ratio of 3:1; finally adding graphene, stirring, and drying in an oven to obtain a powder; S2, the powder is loaded into the mold and pre-pressed to 50-100 MPa; transferred to the isostatic press and pressurized to 200-300 MPa; S3, heating the pressurized powder obtained in step S2 to 1200° C. in an inert atmosphere and calcining the mixture, and then keeping the temperature; Switch to nitrogen atmosphere, heat to 1650-1780℃ for calcination, and keep warm; apply 100-150MPa pressure to obtain a sintered green body; rough grind the sintered green body with a diamond grinding wheel; use an ultra-precision surface grinder for fine processing, with a surface roughness of Ra≤0.01μm; and vacuum package after cleaning.

7. The method for preparing a ceramic guide rail according to claim 6, characterized in that: In step S1, wet ball milling is performed for 8-12 hours, and stirring is performed for 1-2 hours.

8. The method for preparing a ceramic guide rail according to claim 6, wherein: In step S2, pre-pressing is performed to 50-100 MPa and holding the pressure for 5 minutes; pressurizing is performed to 200-300 MPa and holding the pressure for 20-30 minutes; and the green body density is ≥85%.

9. The method for preparing a ceramic guide rail according to claim 6, wherein: In step S3, the temperature is raised to 1200°C at 5°C / min and kept at this temperature for 2 hours; the temperature is raised to 1650-1780°C and kept at this temperature for 1-3 hours.

10. Use of the ceramic guide rail according to any one of claims 1 to 5 or the ceramic guide rail prepared by the preparation method according to any one of claims 6 to 9, characterized in that: The ceramic guide rail is used in ultra-precision machining and ultra-precision measuring instruments.

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