Yag / yb:yag / yag composite laser transparent ceramic and preparation method thereof

Abstract

The application relates to a YAG / Yb:YAG / YAG composite laser transparent ceramic and a preparation method thereof. The Yb:YAG water-based ceramic ink comprises mixed powder composed of Al2O3 powder, Y2O3 powder and Yb2O3 powder, the solid content is 20-25 vol%, the mole ratio of Al2O3, Y2O3 and Yb2O3 is 5:3-x:x, and 0 < x <= 0.3; the dispersant content is 0.2-0.8% of the mass of the mixed powder; the pH control agent is used in an amount controlled to adjust the pH of the Yb:YAG water-based ceramic ink to be between 10-11.5 and the pH of the ink is greater than or equal to 9.5 within 24 hours under the conditions of sealing and 20-25 DEG C; the humectant content is 5-20% of the total volume of the Yb:YAG water-based ceramic ink; the binder content is 0.1-0.5% of the mass of the mixed powder; and the sintering aid content is 0.1-0.5% of the mass of the mixed powder.

Description

Technical Field

[0001] This invention belongs to the field of composite multilayer laser transparent ceramic preparation technology, specifically relating to a YAG / Yb:YAG / YAG composite laser transparent ceramic and its preparation method. Background Technology

[0002] Yttrium aluminum garnet (YAG) is a cubic isotropic crystal formed by mixing Al₂O₃ and Y₂O₃ in a 5:3 molar ratio and then reacting them at high temperature. YAG crystal is a solid-state laser matrix material with excellent optical, thermal, mechanical, and chemical properties. It is produced by doping with rare-earth or other transition metal ions of similar radii to partially replace the Y₂O₃ in the YAG lattice. 3+ The position of the ions can increase the energy level of the metal ions in YAG, thereby enabling laser output of multiple wavelengths.

[0003] Since the advent of solid-state lasers in the 1960s, single-crystal and glass materials have been the primary gain media for solid-state lasers, with Nd:YAG single crystal being a typical example. In 1984, the Dutchman De proposed the idea of ​​using polycrystalline ceramics to replace single crystals and successfully prepared transparent YAG ceramics. In 1995, Ikesu et al. in Japan, through high-purity powder solid-state reaction and vacuum sintering, first prepared YAG and Nd:YAG transparent ceramics with comprehensive properties comparable to single crystals in terms of light absorption and fluorescence, hardness, and thermal conductivity, demonstrating the promising application prospects of polycrystalline YAG ceramics in solid-state lasers. Compared with single crystals, transparent ceramics have the following advantages: lower production cost; simpler production process and shorter cycle time; easier preparation of large-size samples to improve laser output power; and easier achievement of high-concentration rare-earth ion doping to improve laser output power.

[0004] Currently, YAG transparent ceramics are mainly produced by dry pressing of powder, a method that is simple and produces high density after sintering. However, poor powder flow during dry pressing can lead to uneven density distribution in the green body, and the formed shape is limited by the mold, often resulting in simpler shapes. Further processing of more complex ceramic green bodies is also more time-consuming and labor-intensive. Wet forming offers advantages such as good slurry flowability, adjustable solid content, and ease of producing green bodies with uniform density, but the formed shape and size are still limited by the mold.

[0005] For multilayer or planar waveguide-type composite ceramic structures with thin-layer structures, dry pressing is obviously difficult to achieve. Currently, common forming methods are tape casting and bonding. Tape casting uses organic solvents such as ethanol as the ceramic dispersion medium, adding dispersants, sintering aids, binders, plasticizers, lubricants, and other organic additives to form a slurry. This slurry is then applied to a special substrate at a certain thickness using a scraper. After drying and curing, it is peeled off to form a green film. The green film is then processed according to the size and shape requirements of the finished product, such as punching and laminating, to create the finished blank to be sintered. This method offers good thickness uniformity control, but the preparation process is complex and time-consuming. Furthermore, using organic materials as the ceramic dispersion medium significantly increases the difficulty and speed of debonding, potentially resulting in numerous pores after debonding that are difficult to completely eliminate through subsequent heat treatment. Bonding is a method of attracting two sintered heterogeneous materials together to form a composite structure through van der Waals forces or even atomic forces. This method requires very high surface cleanliness and roughness of the bonding surfaces, with roughness often reaching below the nanometer level. It is very difficult to process and there is a certain failure rate after room temperature bonding or hot bonding.

[0006] 3D printing technology can achieve high-precision molding of complex structures and components while retaining the advantages of wet printing. For thin-layer structures of hundreds or even tens of micrometers, direct ink writing (DIW) is limited by the high solids content and high viscosity of the slurry, making it difficult to achieve sub-thickness lines. A more suitable printing method is inkjet printing (IJP), which uses a lower solids content ink-like slurry to improve ink flowability after printing, offering high printing accuracy and speed, and a simpler process. Considering the low organic content of water-based slurries, easier debinding, fewer voids and other defects after debinding, and higher green body density, water-based ceramic inks are a better choice. Summary of the Invention

[0007] To address the aforementioned technical problems, the present invention aims to provide a Yb:YAG water-based ceramic ink (slurry) with excellent rheological properties and its preparation method, as well as a YAG / Yb:YAG / YAG multilayer composite laser transparent ceramic prepared by a molding method combining dry pressing and inkjet printing.

[0008] In a first aspect, the present invention provides a Yb:YAG water-based ceramic ink, the Yb:YAG water-based ceramic ink comprising:

[0009] A mixed powder composed of Al2O3 powder, Y2O3 powder, and Yb2O3 powder; the solid content of the mixed powder is 20-25 vol%, and the molar ratio of Al2O3 powder, Y2O3 powder, and Yb2O3 powder is 5:3-x:x. <x≤0.3;

[0010] Dispersant; the content of the dispersant is 0.2-0.8 wt% of the mass of the mixed powder;

[0011] pH control agent; the dosage of the pH control agent is controlled to adjust the pH of the Yb:YAG water-based ceramic ink to between 10 and 11.5, and the ink pH ≥ 9.5 within 24 hours under sealed conditions at 20-25℃;

[0012] Moisturizer; the content of the moisturizer is 5-20 vol% of the total volume of Yb:YAG water-based ceramic ink;

[0013] Binder; the content of the binder is 0.1-0.5 wt% of the mass of the mixed powder;

[0014] Sintering aid; the content of the sintering aid is 0.1-0.5 wt% of the mass of the mixed powder.

[0015] Preferably, the dispersant is selected from at least one of polyacrylic acid, ammonium polyacrylate, polymethacrylic acid, ammonium polymethacrylate, and PVP;

[0016] The pH control agent is selected from at least one of ammonia, triethanolamine, tetraethylenepentamine, and N-(2-hydroxyethyl)ethylenediamine;

[0017] The moisturizer is selected from at least one of diethylene glycol, glycerin, and propylene glycol methyl ether;

[0018] The adhesive is selected from at least one of PVA, PVB, PEG, and Isobam;

[0019] The sintering aid is selected from at least one of MgO, MgAl2O4, La2O3, Gd2O3, Sc2O3, TiO2, MnO2, SiO2, CaO, CuO, MgCO3, CaCO3, SrCO3, BaCO3, and TEOS.

[0020] Secondly, the present invention provides a method for preparing the above-mentioned Yb:YAG water-based ceramic ink, comprising the following steps: adding Al2O3 raw material powder, Y2O3 raw material powder and Yb2O3 raw material powder to ethanol, and then mixing them by ball milling for the first time, filtering for the first time, drying and sieving to obtain Yb:YAG raw material powder; then, adding water to the Yb:YAG raw material powder and mixing it with dispersant, pH control agent, humectant and sintering aid by ball milling for the second time, filtering for the second time, adding binder and ultrasonically dispersing; and then mixing by centrifugation, centrifugation to degas and remove bubbles to obtain the Yb:YAG water-based ceramic ink.

[0021] Preferably, the purity of Al2O3 raw material powder is ≥99.9% and the particle size is 0.1-1μm; the purity of Y2O3 raw material powder is ≥99.9% and the particle size is 0.5-10μm; and the purity of Yb2O3 raw material powder is ≥99.9% and the particle size is 0.5-10μm.

[0022] Preferably, the first and second ball milling processes use Al2O3 grinding balls with a particle size of 3 mm and / or 5 mm.

[0023] The ethanol used in the first ball milling is chemically pure, and the amount added is 0.8-1.5 times the total mass of Al2O3 powder, Y2O3 powder, and Yb2O3 powder. The ball milling time is 18-48 hours, and the ball milling speed is 80-200 r / min. The first filtration uses a funnel-shaped sieve with a mesh size of 40-60. The drying temperature is 50-120℃, and the drying time is 12-36 hours. The sieving process uses a sieve with a mesh size of 60-120, and the sieving is performed 1-3 times.

[0024] The water used for the second ball milling is deionized water, and the amount added is calculated according to the solid content requirements of the ink; the mass ratio of the Yb:YAG raw material powder to the Al2O3 grinding balls is 1:1.6-2.5; the ball milling time is 18-32 hours, and the ball milling speed is 100-200 r / min; the second filtration uses a funnel-shaped screen with a mesh size of 40-60 mesh;

[0025] The ultrasonic dispersion frequency is 50-53kHz, and the ultrasonic time is 5-10min.

[0026] Preferably, the centrifugal mixing speed is 1000-2000 r / min and the centrifugation time is 3-6 min; the centrifugal degassing speed is 1000-2000 r / min and the time is 5-10 min, and the vacuum degree is 1-10 kPa.

[0027] Thirdly, the present invention provides a method for preparing YAG / Yb:YAG / YAG composite laser transparent ceramic, comprising the following steps: mixing Al2O3 raw material powder and Y2O3 raw material powder to obtain YAG raw material powder; then, dry pressing the YAG raw material powder into a YAG first layer preform; then, 3D inkjet printing the aforementioned Yb:YAG water-based ceramic ink onto the YAG first layer preform to form a Yb:YAG layer preform; then, dry pressing the YAG raw material powder onto the Yb:YAG layer preform to form a YAG second layer preform, thereby obtaining a YAG / Yb:YAG / YAG composite laser transparent ceramic preform; after cold isostatic pressing, debinding, sintering, hot isostatic pressing, and annealing, the YAG / Yb:YAG / YAG composite laser transparent ceramic is obtained.

[0028] Preferably, the mixing method of the YAG raw material powder is the same as the mixing method of the Yb:YAG raw material powder described above.

[0029] Preferably, the process parameters for the 3D inkjet printing include: surface air pressure of 0.2-5 psi, voltage signal frequency of 20-100 Hz, pulse time of 0.3-0.5 ms, nozzle orifice diameter of 50-100 μm, printing line speed of 8-20 mm / s, and printing line spacing of 0.2-0.5 mm.

[0030] Preferably, the cold isostatic pressing pressure is 180-250 MPa, and the time is 0.5-2 h;

[0031] The debonding environment is air, the temperature is 600-1000℃, and the time is 1-3 hours;

[0032] The sintering is carried out under vacuum, with the gas pressure controlled to be ≤10. -2 Pa, temperature 1640-1750℃, time 8-15h;

[0033] The atmosphere for the hot isostatic pressing is argon, with a pressure of 160-250 MPa, a temperature of 1600-1700 °C, and a time of 3-6 h.

[0034] The annealing atmosphere is air or oxygen, the temperature is 1250-1350℃, and the time is 10-20h.

[0035] Fourthly, the present invention provides a YAG / Yb:YAG / YAG composite laser transparent ceramic obtained according to the above preparation method, wherein the YAG and Yb:YAG components are both cubic isotropic structures with an average grain size of 2-10 μm, a relative density of ≥99.9%, and a Yb:YAG layer thickness of 50-250 μm;

[0036] When the thickness of the YAG / Yb:YAG / YAG composite laser-transparent ceramic sample is 4.5-5.5 mm, the linear transmittance at a wavelength of 1030 nm is ≥80%.

[0037] Beneficial effects

[0038] (1) The Yb:YAG water-based ceramic ink of the present invention has high dispersibility and stability and can remain unsettled and stratified within a certain time.

[0039] (2) The Yb:YAG water-based ceramic ink of the present invention has the characteristics of low solid content and low viscosity, and is especially suitable for inkjet printing of thin ceramic samples with flexible shape and size for 3D printing.

[0040] (3) The Yb:YAG water-based ceramic ink of the present invention can produce YAG / Yb:YAG / YAG composite transparent ceramic with good optical quality through inkjet printing, dry pressing and subsequent densification and heat treatment processes, which proves the practicality of the ceramic ink.

[0041] (4) The Yb:YAG water-based ceramic ink of the present invention does not contain toxic heavy metal ions, and the organic matter it contains has low toxicity and low content. It can be completely decomposed into harmless gas during the heat treatment process, making it a healthy and environmentally friendly preparation material.

[0042] (5) The raw materials used in this invention are stable and the molding and densification processes are stable and adjustable. It can be mass-produced with a fixed process or the process parameters can be finely adjusted to meet the needs of various application scenarios. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the YAG / Yb:YAG / YAG composite laser transparent ceramic prepared in Example 1 and its transmittance curve.

[0044] Figure 2 The viscosity of the Yb:YAG water-based ceramic ink used in Example 1 and Comparative Examples 1 and 2 is a curve showing the change in viscosity with shear rate.

[0045] Figure 3 The images show the inkjet printing results on dry-pressed YAG preforms using the ink from Example 1 (right side) and the ink from Comparative Example 2 (left side).

[0046] Figure 4 This is a schematic diagram showing the sedimentation effect of the Yb:YAG water-based ceramic ink used in Examples 1 and 2 and Comparative Examples 3 and 4 after being left to stand in a sealed sample bottle for one week.

[0047] Figure 5 These are schematic diagrams of composite ceramic samples after hot isostatic pressing treatment, as shown in Example 2 (left) and Comparative Example 5 (right). Detailed Implementation

[0048] The present invention is further illustrated by the embodiments described below. It should be understood that the embodiments described below are for illustrative purposes only and are not intended to limit the present invention.

[0049] The following exemplifies the preparation method of the YAG / Yb:YAG (ytterbium-doped yttrium aluminum garnet) / YAG composite laser-transparent ceramic provided by the present invention. The preparation method of the YAG / Yb:YAG / YAG composite laser-transparent ceramic may include the following steps.

[0050] (1) Preparation of YAG raw material powder. Al2O3 raw material powder, Y2O3 raw material powder, ethanol, and high-purity Al2O3 grinding balls were ball-milled and mixed in a ball mill jar. After filtration, drying and sieving, the YAG raw material powder was obtained.

[0051] In some embodiments, the purity of the Al2O3 raw material powder is ≥99.9%, and the particle size is 0.1-1 μm; the purity of the Y2O3 raw material powder is ≥99.9%, and the particle size is 0.5-10 μm. Preferably, the molar ratio of the Al2O3 raw material powder to the Y2O3 raw material powder is 5:3.

[0052] In some embodiments, the ethanol can be chemically pure, and the amount added can be controlled to be 0.8-1.5 times the total mass of Al2O3 raw material powder and Y2O3 raw material powder.

[0053] In some embodiments, the particle size of the high-purity Al2O3 grinding balls can be 3mm or / and 5mm; the mass ratio of the total mass of Al2O3 raw material powder and Y2O3 raw material powder to the mass of the high-purity Al2O3 grinding balls can be controlled to be 1:1.6-2.5; the volume of the grinding jar can be 1-5L, the grinding speed can be 80-200r / min, and the grinding time can be 18-48h; preferably, the grinding jar volume is 5L, the grinding speed is 100r / min, and the grinding time is 48h.

[0054] In some embodiments, the filter may employ a funnel-shaped screen with a mesh size of 40-60.

[0055] In some embodiments, the drying temperature can be 50-120°C and the drying time can be 12-36 hours; preferably, the drying temperature is 80°C and the drying time is 18 hours.

[0056] In some embodiments, the sieve mesh size of the sieving process can be 60-120 mesh, and the sieving process can be 1-3 times; preferably, the sieve mesh size is 100 mesh, and the sieving process is 2 times.

[0057] (2) Preparation of Yb:YAG raw material powder. Al2O3 raw material powder, Y2O3 raw material powder and Yb2O3 raw material powder were mixed with ethanol and high-purity Al2O3 grinding balls in a ball mill jar for the first ball milling. After filtration, drying and sieving, the Yb:YAG raw material powder was obtained.

[0058] In some embodiments, the purity of the Al2O3 raw material powder is ≥99.9%, and the particle size is 0.1 - 1 μm; the purity of the Y2O3 raw material powder is ≥99.9%, and the particle size is 0.5 - 10 μm; the purity of the Yb2O3 raw material powder is ≥99.9%, and the particle size is 0.5 - 10 μm. Preferably, the molar ratio of the Al2O3 raw material powder, Y2O3 raw material powder, and Yb2O3 raw material powder can be 5:3 - x:x, where 0 < x ≤ 0.3. If the value of x is too large, it will lead to too high Yb concentration, which is likely to cause concentration quenching and reduce the luminescence efficiency of the Yb:YAG ceramic.

[0059] In some embodiments, the purity of the ethanol can be chemically pure, and the addition amount can be controlled to be 0.8 - 1.5 times the total mass of the Al2O3 raw material powder, Y2O3 raw material powder, and Yb2O3 raw material powder.

[0060] In some embodiments, the particle size of the high-purity Al2O3 grinding balls can be 3 mm and / or 5 mm; the mass ratio of the total mass of the Al2O3 raw material powder, Y2O3 raw material powder, and Yb2O3 raw material powder to the mass of the high-purity Al2O3 grinding balls can be 1:1.6 - 2.5; the volume of the ball mill tank can be 1 - 5 L, the ball mill rotation speed can be 80 - 200 r / min, and the ball mill time can be 18 - 48 h; preferably, the volume of the grinding tank is 5 L, the ball mill rotation speed is 100 r / min, and the ball mill time is 48 h.

[0061] In some embodiments, the filtration can be carried out using a funnel-shaped screen with a mesh size of 40 - 60.

[0062] In some embodiments, the drying temperature can be 50 - 120 °C, and the drying time can be 12 - 36 h; preferably, the drying temperature is 80 °C, and the drying time is 18 h.

[0063] In some embodiments, the mesh size of the screen for the screening process can be 60 - 120 mesh, and the number of screening times can be 1 - 3 times; preferably, the mesh size of the screen is 100 mesh, and the number of screening times is 2 times.

[0064] (3) Preparation of Yb:YAG water-based ceramic ink. Add the Yb:YAG raw material powder to deionized water, and then place it in a ball mill tank together with a dispersant, pH controller, humectant, sintering aid, and high-purity Al2O3 grinding balls for secondary ball milling and mixing to be uniformly dispersed. Then, filter the ball-milled mixed solution into a degassing tank, add a binder to the filtrate for ultrasonic dispersion, and finally place the degassing tank containing the mixed solution in a centrifuge for centrifugal mixing, centrifugal defoaming and degassing, and filter to obtain the Yb:YAG water-based ceramic ink.

[0065] Among them, sintering aids can be added before ball milling, but binders cannot, because ball milling takes a long time, and prolonged mixing of binders with other slurries will greatly increase the viscosity of the slurry, thereby reducing the dispersion effect and printability of the ink.

[0066] In some embodiments, the dispersant may be selected from at least one of polyacrylic acid, ammonium polyacrylate, polymethacrylic acid, ammonium polymethacrylate, and PVP; the pH control agent may be selected from at least one of ammonia, triethanolamine, tetraethylenepentamine, and N-(2-hydroxyethyl)ethylenediamine; the humectant may be selected from at least one of diethylene glycol, glycerin, and propylene glycol methyl ether; the binder may be selected from at least one of PVA, PVB, PEG, and Isobam; and the sintering aid may be selected from at least one of MgO, MgAl2O4, La2O3, Gd2O3, Sc2O3, TiO2, MnO2, SiO2, CaO, CuO, MgCO3, CaCO3, SrCO3, BaCO3, and TEOS.

[0067] In some embodiments, the purity of the dispersant, pH control agent, and binder can be chemically pure; the purity of the humectant and sintering aid can be analytically pure.

[0068] In some embodiments, the mass ratio of the Yb:YAG raw material powder to the high-purity Al2O3 grinding balls can be 1:1.6-2.5; preferably, the particle size of the high-purity Al2O3 grinding balls can be 3 mm and / or 5 mm.

[0069] In some embodiments, the ball mill jar volume can be 500ml, the ball milling time can be 18-32h, and the rotation speed can be 100-200r / min; preferably, the ball milling time is 24h and the rotation speed is 120r / min. If the ball milling time is too short, the powder in the slurry will not be sufficiently dispersed, and some particles will agglomerate; if the ball milling time is too long, the moisture in the slurry will easily evaporate slowly from the micro-gap at the jar opening, thereby increasing the solid content and viscosity of the slurry and affecting the inkjet printing effect.

[0070] In some embodiments, the filter may employ a funnel-shaped screen with a mesh size of 40-60.

[0071] In some embodiments, the ultrasonic frequency of the ultrasonic dispersion can be 50-53 kHz, and the ultrasonic duration can be 5-10 min.

[0072] In some embodiments, the centrifugal mixing speed can be 1000-2000 r / min, and the centrifugation time can be 3-6 min; preferably, the centrifugation speed is 1500 r / min, and the centrifugation time is 5 min.

[0073] In some embodiments, the centrifugal degassing speed can be 1000-2000 r / min, the time can be 5-10 min, and the vacuum degree can be 1-10 kPa; preferably, the centrifugal speed is 1500 r / min, the time is 6 min, and the vacuum degree is 1 kPa.

[0074] In some embodiments, the solid content of the mixed powder composed of Al2O3 powder, Y2O3 powder, and Yb2O3 powder in the Yb:YAG water-based ceramic ink can be controlled to be 20-25 vol%. The content of the dispersant can be controlled to be 0.2-0.8 wt% of the mass of the mixed powder. The content of the pH control agent can be controlled to adjust the pH of the Yb:YAG water-based ceramic ink to between 10 and 11.5, and the pH of the ink ≥ 9.5 within 24 hours under sealed conditions at 20-25°C. The content of the humectant can be controlled to be 5-20 vol% of the total volume of the Yb:YAG water-based ceramic ink. The content of the binder can be 0.1-0.5 wt% of the total mass of the mixed powder. The content of the sintering aid can be 0.1-0.5 wt% of the mass of the mixed powder.

[0075] In some embodiments, the viscosity of the Yb:YAG water-based ceramic ink can be controlled to be 1-100 mPa·s at a shear rate exceeding 100 / s, preferably 1-20 mPa·s, and more preferably 3-10 mPa·s. If the viscosity is too low, the ink flow on the substrate will be too strong, reducing the precision of the printed edges; if the ink viscosity is too high, ink jetting will be difficult, the ink flow on the substrate will be too weak, the uniformity of the green body after drying will decrease, and the printed green body will be prone to cracking or warping.

[0076] In some implementations, the Yb:YAG water-based ceramic ink can be controlled to prevent delamination within 48 hours. The ink exhibits good rheological properties, meeting the time requirements for composite ceramic dry pressing and inkjet printing processes.

[0077] If the solid content of Yb:YAG water-based ceramic ink is too low, the ink in the subsequent 3D inkjet printing nozzle will flow out of the nozzle without being controlled by the piezoelectric signal, and the ink flow on the substrate will be too strong, reducing the dimensional accuracy of the edges. If the solid content of Yb:YAG water-based ceramic ink is too high, the ink will be difficult to eject from the 3D inkjet printing nozzle under high air pressure or the nozzle will be easily blocked during the ejection process, and the ink flow on the substrate will be too weak, reducing the uniformity of the green body after drying.

[0078] Insufficient dispersant content leads to inadequate powder dispersion and agglomeration of some powder particles; excessive dispersant content saturates the powder dispersion effect, increasing organic matter content and negatively impacting subsequent debinding. Furthermore, since dispersants primarily disperse particles through steric hindrance and electrostatic repulsion, they require a specific pH environment to achieve optimal dispersion. Adding an appropriate amount of pH control agent can regulate the solvent pH to a region with a high absolute value of the zeta potential, improving the dispersant's dispersion effect. The addition of a humectant can slow down ink viscosity at the printhead during printing, preventing excessive evaporation and printhead clogging, and also slows down the evaporation rate of moisture on the wet blank on the dry-pressed substrate after printing, preventing cracking. Insufficient humectant weakens these effects, while excessive humectant leads to excessive organic matter content, also affecting debinding. A binder is used to appropriately increase ink viscosity, thereby improving the ink's shape retention after printing. Insufficient binder results in high ink flowability and low printing accuracy; excessive binder makes it difficult for the ink to level on the substrate and easily clogs the printhead. The addition of sintering aids can improve the sintering activity of oxide raw materials and reduce the sintering temperature. Too little content will lead to a higher required sintering temperature and higher energy consumption; too much content will lead to the introduction of more other metal ion impurities, affecting optical quality.

[0079] The Yb:YAG water-based ceramic ink prepared by the method provided in this invention uses Al2O3 powder, Y2O3 powder, and Yb2O3 powder as main raw materials. By adding water, dispersants, and pH adjusters, ceramic particles in water can be dispersed, reducing sedimentation. A small amount of binder is added to adjust the ink viscosity. A humectant is added to reduce water evaporation and stabilize the ink viscosity and solid content. The ink solid content is determined by controlling the amount of water, pH adjuster, and humectant added. Considering the hydration effect of oxide ceramic powder, an appropriate amount of water is added to fully compensate for the free water lost in the reaction with the oxide ceramic, thus stabilizing the solid content. A small amount of sintering aid is added to assist in the sintering, densification, and transparency of the ceramic powder.

[0080] (4) Preparation of YAG / Yb:YAG / YAG composite laser transparent ceramic. YAG raw material powder is dry-pressed into a YAG first-layer preform. Then, Yb:YAG water-based ceramic ink is 3D inkjet printed on the YAG first-layer preform to form a Yb:YAG layer preform. Next, YAG raw material powder is dry-pressed on the Yb:YAG layer preform to form a YAG second-layer preform, thus obtaining a YAG / Yb:YAG / YAG composite laser transparent ceramic preform. After cold isostatic pressing, debinding, sintering, hot isostatic pressing and annealing, the YAG / Yb:YAG / YAG composite laser transparent ceramic is obtained.

[0081] In some embodiments, the process of dry pressing the YAG raw material powder into a YAG first-layer blank can be as follows: the YAG powder is loaded into a metal mold with a cross-sectional dimension of 40×20mm and shaken to flatten and compact it. Then, the closed mold is pressed to an actual pressure of 20-30MPa using a single-axis press, and the mold is demolded to obtain the YAG first-layer blank.

[0082] In some embodiments, the process of forming a Yb:YAG layer preform by 3D inkjet printing Yb:YAG water-based ceramic ink can be as follows: the Yb:YAG water-based ceramic ink is loaded into the 3D inkjet printer syringe and connected to the surface air path, and then the Yb:YAG water-based ceramic ink is printed on the first YAG preform by controlling the nozzle with piezoelectric ceramic according to the set printing program, and then dried to obtain a Yb:YAG layer preform.

[0083] The surface air path pressure can be 0.2-5 psi; the voltage signal frequency of the piezoelectric ceramic control nozzle can be 20-100 Hz, the pulse time can be 0.3-0.5 ms; the nozzle orifice diameter can be 50-100 μm, the printing line speed can be 8-20 mm / s, and the printing line spacing can be 0.2-0.5 mm.

[0084] The printing parameters can be adjusted based on the actual printing results. For well-mixed ink with stable rheological properties, air pressure affects the jetting speed. Too low an air pressure makes it difficult for the nozzle to eject ink, while too high an air pressure results in thicker jet lines, reduced precision, and the accumulation of large droplets at the nozzle, causing the jet to deviate or even split. The voltage signal frequency and opening time control the opening time of the printhead, thus affecting the jetting speed. A smaller printhead orifice diameter promotes finer, more precise lines, but an excessively small orifice diameter may lead to difficulty in ink ejection or even printhead clogging. Printing linear velocity is the translational speed of the printhead. When the ink jetting speed is constant, too low a linear velocity will cause excessive ink accumulation per unit length of line, increasing the printed layer thickness; too high a linear velocity can easily lead to uneven or even discontinuous line widths. The line spacing in printing is the distance between the central axes of two adjacent printed lines. When the ink rheological properties, jet speed, and printing line speed are constant, the width of the printed lines is also constant. If the line spacing is too small, the two adjacent lines will partially overlap. Even if the ink can flow evenly, it will increase the thickness of the printed layer. If it cannot flow evenly, it will increase the thickness of the overlapping area, resulting in uneven printed layer thickness. If the line spacing is too large, it will reduce the thickness of the adjacent area of ​​the two adjacent lines or even create gaps, which will also result in uneven printed layer thickness.

[0085] In some embodiments, the cold isostatic pressing pressure can be 180-220 MPa, and the time can be 0.5-2 h; the debonding environment can be air, the temperature can be 600-1000 °C, and the time can be 1-3 h; the sintering can be carried out under vacuum, with the gas pressure controlled ≤10. -2 The pressure can be 1640-1750℃, the temperature can be 1600-1700℃, and the time can be 8-15h; the hot isostatic pressure atmosphere can be argon, the pressure can be 160-250MPa, the temperature can be 1600-1700℃, and the time can be 3-6h; the annealing atmosphere can be air or oxygen, the temperature can be 1250-1350℃, and the time can be 10-20h.

[0086] Cold isostatic pressing (COP) can improve the density of the green body after dry pressing. Insufficient pressure and time will lead to insufficient density, making it prone to cracking after COP or during sintering. Debinding removes residual organic matter from the composite ceramic green body. Insufficient temperature and time will result in incomplete or no decomposition of the organic matter, while excessive temperature and time will cause powder remelting and grain growth before the organic matter decomposition process is complete, leading to an increase in defects within the sample. Sintering is the process of powder remelting and grain growth after debinding. Insufficient temperature and time will result in an incomplete process, with low crystallinity and numerous defects such as pores; excessive temperature and time will cause excessive grain growth, reducing the sample's strength. Hot isostatic pressing (HIP) is the process of migrating and eliminating defects such as pores within the sample after sintering. Insufficient temperature, pressure, and time will result in incomplete defect elimination. Exceeding reasonable temperature, pressure, and time will not only fail to significantly improve defect elimination but will also affect the service life of the equipment or even cause damage. Annealing is the process of eliminating internal stress and oxidizing all Yb ions to +3 valence after hot isostatic pressing. Insufficient temperature and time will lead to incomplete annealing, resulting in lower sample strength and transmittance. Excessive temperature and time will cause grain remelting and recrystallization within the sample, reducing the effectiveness of sintering and hot isostatic pressing.

[0087] The phase formation of YAG occurs through solid-state reactions during the sintering process after molding, as follows: Al₂O₃ + 2Y₂O₃ → Y₄Al₂O₉ (YAM): (900-1100℃); Y₄Al₂O₉ + Al₂O₃ → 4YAlO₃ (YAP): (1100-1250℃); 3YAlO₃ + Al₂O₃ → Y₃Al₅O₂ 12(YAG): (1400-1600℃). In this invention, the raw materials for forming the Yb:YAG structure are Al2O3, Y2O3 and Yb2O3 powders. The phase formation of Yb:YAG is also carried out through solid-state reaction during the sintering process after molding. The process is similar to that of YAG, except that Yb2O3 gradually replaces part of Y2O3 and Al2O3 in the reaction.

[0088] The YAG / Yb:YAG / YAG composite laser-transparent ceramic obtained by the preparation method provided by this invention has YAG and Yb:YAG components as cubic isotropic structures with an average grain size of 2-10 μm, a relative density ≥99.9%, and a Yb:YAG layer thickness of 50-250 μm. Specifically, when the thickness of the YAG / Yb:YAG / YAG composite laser-transparent ceramic sample is 4.5-5.5 mm, the linear transmittance at a wavelength of 1030 nm is ≥80%.

[0089] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention fall within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0090] Example 1

[0091] The method for preparing YAG / Yb:YAG / YAG composite laser-transparent ceramics provided in this embodiment includes the following steps:

[0092] (1) Preparation of YAG raw material powder. Al2O3 raw material powder (purity ≥99.9%, average particle size 0.24μm) and Y2O3 raw material powder (purity ≥99.9%, average particle size 4.11μm) were weighed at a mass ratio of 1:1.33 (molar ratio 5:3). Then, high-purity Al2O3 grinding balls with a mass ratio of 2:1.33 and an amount of ethanol equal to the total mass of the two powders were weighed and added together into a 5L ball mill jar. The mixture was ball milled at 100r / min for 48h. The mixture was then filtered through a funnel-shaped sieve, dried at 80℃ for 18h, and sieved twice through a 100-mesh sieve to obtain the YAG raw material powder.

[0093] (2) Preparation of Yb:YAG raw material powder. Al2O3 (purity ≥99.9%, average particle size 0.24μm), Y2O3 (purity ≥99.9%, average particle size 4.11μm) and Yb2O3 powder (purity ≥99.9%, average particle size 1μm) were weighed according to the mass ratio of 254.90:321.79:29.55 (molar ratio 5:2.85:0.15) respectively, and the Yb:YAG raw material powder was obtained by referring to the preparation process in step (1).

[0094] (3) Preparation of Yb:YAG water-based ceramic ink. 30g of Yb:YAG raw material powder was weighed and prepared according to a solid content of 20 vol%. A solution with pH=11 was prepared using ammonia and water. Considering the hydration effect of the oxide ceramic powder, 29.3ml of ammonia solution was measured as the solvent. 0.1846g of 65wt.% CE-64 (polymethyl methacrylate) aqueous solution was weighed as the dispersant (CE-64 accounts for 0.4wt.% of the mixed powder mass), 5.2ml of diethylene glycol was used as the humectant (20 vol% of the total volume of the water-based ceramic ink), and 66g of high-purity Al2 with a particle size of 5mm was weighed. O3 grinding balls were ball-milled in a 0.5L nylon container at 120 rpm for 24 hours. Then, the mixture was filtered through a funnel-shaped sieve into a degassing tank. 0.03 g of polyethylene glycol 400 as a binder and 0.03 g of MgO as a sintering aid were weighed and added to the degassing tank. The mixture was ultrasonically sonicated at 50 Hz for 5 minutes, then mixed in a centrifugal mixer at 1500 rpm for 5 minutes. Finally, the mixture was degassed in a vacuum environment of 1 kPa at 1500 rpm for 6 minutes and filtered to obtain the Yb:YAG water-based ceramic ink.

[0095] (4) Preparation of YAG / Yb:YAG / YAG composite laser transparent ceramic. 10g of YAG raw material powder was weighed and spread evenly in a 40×20mm rectangular mold, pressurized to an actual pressure of 20MPa, and a layer of Yb:YAG water-based ceramic ink was inkjet printed onto the dry-pressed powder. The printing parameters were: surface gas pressure of 0.8psi, voltage signal frequency of the piezoelectric ceramic control nozzle of 25Hz, pulse time of 0.4ms, nozzle orifice diameter of 100μm, linear velocity of 12mm / s, and line spacing of 0.3mm. Then, another 10g... YAG raw material powder was evenly spread on the printed blank and pressurized to an actual pressure of 30 MPa to obtain a YAG / Yb:YAG / YAG composite laser transparent ceramic blank. Next, the blank was vacuum-sealed and cold isostatically pressed in hydraulic oil at a pressure of 200 MPa for 2 hours to increase its density. Then, the blank was placed in an air atmosphere debinding furnace at a temperature of 800℃ for 2 hours to debind it. The debinded blank was then sintered in a vacuum environment sintering furnace at a pressure of 5 × 10⁻⁶ MPa. -3The sample was sintered at 1680℃ for 12 hours under argon atmosphere. After sintering, it was subjected to hot isostatic pressing (HIP) at 200 MPa, 1650℃, and 4 hours in an argon atmosphere furnace. The HIP sample was then annealed at 1290℃ for 15 hours in an oxygen atmosphere furnace. Finally, the sample was cut to the required size and polished on both sides to obtain the YAG / Yb:YAG / YAG composite laser-transparent ceramic.

[0096] The YAG / Yb:YAG / YAG composite laser-transparent ceramic prepared in Example 1 has a cubic isotropic structure with an average grain size of 3.14 μm and a relative density of 99.9%. The thickness of the Yb:YAG component is 70 μm. When the thickness of the composite ceramic sample is 5.5 mm, the linear transmittance at a wavelength of 1030 nm is 80.75% (see Example 1). Figure 1 ).

[0097] Example 2

[0098] The preparation method of this Example 2 is the same as that of Example 1, the main difference being: in step (2), the mass ratio of Al2O3, Y2O3 and Yb2O3 powder is adjusted to 254.90:304.86:59.10 (molar ratio 5:2.7:0.3); in step (3), the ink ball milling dispersion time is 32h.

[0099] The YAG / Yb:YAG / YAG composite laser transparent ceramic prepared in Example 2 has a cubic isotropic structure with an average grain size of 2.27 μm and a relative density of 99.9%. The thickness of the Yb:YAG layer is 200 μm. When the thickness of the composite ceramic sample is 4.5 mm, the linear transmittance at a wavelength of 1030 nm is 81.73%.

[0100] Comparative Example 1

[0101] The preparation method of Comparative Example 1 is the same as that of Example 1, the main difference being: in step (3), the total amount of water and ammonia solution added is adjusted to 39.0 ml, the amount of diethylene glycol added is 6 ml, and the ink solid content is controlled to be 10 vol%.

[0102] Comparative Example 2

[0103] The preparation method of Comparative Example 2 is the same as that of Example 1, the main difference being that in step (3), the total amount of water and ammonia solution added is adjusted to 14.2 ml, the amount of diethylene glycol added is 1.5 ml, and the ink solid content is controlled to be 30 vol%.

[0104] Figure 2The graph shows the viscosity of the Yb:YAG water-based ceramic ink used in Example 1 and Comparative Examples 1 and 2 as a function of shear rate. As can be seen from the graph, when the shear rate exceeds 100 / s, the viscosity of Example 1 and Comparative Example 2 is between 3 and 10 mPa·s, while the viscosity of Comparative Example 1 is lower. This would cause ink leakage to begin during inkjet printing even without the application of a piezoelectric signal.

[0105] Figure 3 The images show the inkjet printing results on dry-pressed YAG preforms using the ink from Example 1 (right side) and the ink from Comparative Example 2 (left side). As can be seen from the images, the ink prepared in Example 1 forms well on the dry-pressed YAG preform, while the ink from Comparative Example 2 quickly cracks on the dry-pressed YAG preform.

[0106] Comparative Example 3

[0107] The preparation method of Comparative Example 3 is the same as that of Example 1, the main difference being that in step (3), the ink ball milling dispersion time is 8h.

[0108] Comparative Example 4

[0109] The preparation method of Comparative Example 4 is the same as that of Example 1, the main difference being that in step (3), the ink ball milling dispersion time is 16h.

[0110] Figure 4 This diagram illustrates the sedimentation effect of the Yb:YAG water-based ceramic inks used in Examples 1 and 2, and Comparative Examples 3 and 4, after being left to stand in sealed sample bottles for one week. As can be seen from the diagram, the inks from Example 1 (ball-milled for 24 hours) and Example 2 (ball-milled for 32 hours) showed only minor supernatant stratification, indicating relatively stable inks. In contrast, the inks from Comparative Examples 3 and 4 exhibited significant sedimentation and stratification.

[0111] Comparative Example 5

[0112] The preparation method of Comparative Example 5 is the same as that of Example 1, the main difference being that in step (4), the printing line speed is 25 mm / s and the printing line spacing is 0.5 mm.

[0113] Figure 5 These are schematic diagrams of the composite ceramic samples after hot isostatic pressing (HIP) treatment in Example 2 (left) and Comparative Example 5 (right). As can be seen from the figures, the printed layer in Example 2 is more uniform, while the thickness in Comparative Example 5 is less uniform in the areas of the printed lines and gaps between them.

[0114] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for preparing YAG / Yb:YAG / YAG composite laser-transparent ceramics, characterized in that, Includes the following steps: Al2O3 raw material powder and Y2O3 raw material powder are mixed to obtain YAG raw material powder. Then, the YAG raw material powder is dry-pressed into a YAG first-layer preform. Next, Yb:YAG water-based ceramic ink is 3D inkjet printed on the YAG first-layer preform to form a Yb:YAG layer preform. Then, YAG raw material powder is dry-pressed on the Yb:YAG layer preform to form a YAG second-layer preform, resulting in a YAG / Yb:YAG / YAG composite laser transparent ceramic preform. After cold isostatic pressing, debinding, sintering, hot isostatic pressing and annealing, the YAG / Yb:YAG / YAG composite laser transparent ceramic is obtained. The Yb:YAG water-based ceramic ink includes: A mixed powder composed of Al2O3 powder, Y2O3 powder, and Yb2O3 powder; the solid content of the mixed powder is 20-25 vol%, and the molar ratio of Al2O3 powder, Y2O3 powder, and Yb2O3 powder is 5:3-x:x, where 0 < x ≤ 0.3; Dispersant; the content of the dispersant is 0.2-0.8 wt% of the mass of the mixed powder; pH control agent; the dosage of the pH control agent is controlled to adjust the pH of the Yb:YAG water-based ceramic ink to between 10 and 11.5, and the ink pH ≥ 9.5 within 24 hours under sealed conditions at 20-25℃; Moisturizer; the content of the moisturizer is 5-20 vol% of the total volume of Yb:YAG water-based ceramic ink. Binder; the content of the binder is 0.1-0.5 wt% of the mass of the mixed powder; Sintering aid; the content of the sintering aid is 0.1-0.5 wt% of the mass of the mixed powder; The process parameters for the 3D inkjet printing of Yb:YAG water-based ceramic ink include: surface gas pressure of 0.2-5psi, voltage signal frequency of 20-100Hz, pulse time of 0.3-0.5ms, nozzle orifice diameter of 50-100μm, printing line speed of 8-20mm / s, and printing line spacing of 0.2-0.5mm.

2. The preparation method according to claim 1, characterized in that, The dispersant is selected from at least one of polyacrylic acid, ammonium polyacrylate, polymethacrylic acid, ammonium polymethacrylate, and PVP; The pH control agent is selected from at least one of ammonia, triethanolamine, tetraethylenepentamine, and N-(2-hydroxyethyl)ethylenediamine; The moisturizer is selected from at least one of diethylene glycol, glycerin, and propylene glycol methyl ether; The adhesive is selected from at least one of PVA, PVB, PEG, and Isobam; The sintering aid is selected from at least one of MgO, MgAl2O4, La2O3, Gd2O3, Sc2O3, TiO2, MnO2, SiO2, CaO, CuO, MgCO3, CaCO3, SrCO3, BaCO3, and TEOS.

3. The preparation method according to claim 1, characterized in that, The preparation process of the Yb:YAG water-based ceramic ink includes the following steps: Al2O3 raw material powder, Y2O3 raw material powder and Yb2O3 raw material powder are added to ethanol and then mixed by ball milling for the first time, filtered for the first time, dried and sieved to obtain Yb:YAG raw material powder; then, water is added to the Yb:YAG raw material powder and then mixed with dispersant, pH control agent, humectant and sintering aid by ball milling for the second time, filtered for the second time, and then a binder is added and ultrasonically dispersed; after centrifugal mixing and centrifugal degassing, the Yb:YAG water-based ceramic ink is obtained.

4. The preparation method according to claim 3, characterized in that, The purity of Al2O3 raw material powder is ≥99.9%, and the particle size is 0.1-1μm; the purity of Y2O3 raw material powder is ≥99.9%, and the particle size is 0.5-10μm; the purity of Yb2O3 raw material powder is ≥99.9%, and the particle size is 0.5-10μm.

5. The preparation method according to claim 3, characterized in that, The first and second ball milling mixtures use Al2O3 grinding balls with a particle size of 3 mm and / or 5 mm. The first ball milling mixing uses chemically pure ethanol as the solvent, and the amount added is 0.8-1.5 times the total mass of Al2O3 powder, Y2O3 powder, and Yb2O3 powder. The ball milling mixing time is 18-48 hours, and the ball milling speed is 80-200 r / min. The first filtration uses a funnel-shaped sieve with a mesh size of 40-60 mesh. The drying temperature is 50-120℃, and the drying time is 12-36 hours. The sieving process uses a sieve with a mesh size of 60-120 mesh, and the sieving is performed 1-3 times. The water used for the second ball milling mixing is deionized water, and the amount added is calculated according to the ink solid content requirements; the mass ratio of Yb:YAG raw material powder to Al2O3 grinding balls is 1:1.6-2.5; the ball milling time is 18-32 hours, and the ball milling speed is 100-200 r / min; the second filtration uses a funnel-shaped screen with a mesh size of 40-60 mesh; The ultrasonic dispersion frequency is 50-53kHz, and the ultrasonic time is 5-10min.

6. The preparation method according to claim 3, characterized in that, The centrifugal mixing speed is 1000-2000 r / min, and the centrifugation time is 3-6 min; the centrifugal degassing speed is 1000-2000 r / min, the time is 5-10 min, and the vacuum degree is 1-10 kPa.

7. The preparation method according to claim 1, characterized in that, The mixing method of the YAG raw material powder is the same as the mixing method of the Yb:YAG raw material powder according to claim 3.

8. The preparation method according to claim 1, characterized in that, The pressure of the cold isostatic pressing is 180-250 MPa, and the time is 0.5-2 h; The debonding environment is air, the temperature is 600-1000℃, and the time is 1-3 hours; The sintering is carried out under vacuum, with the gas pressure controlled to be ≤10. -2 Pa, temperature 1640-1750℃, time 8-15h; The atmosphere for the hot isostatic pressing is argon, with a pressure of 160-250 MPa, a temperature of 1600-1700 °C, and a time of 3-6 h. The annealing atmosphere is air or oxygen, the temperature is 1250-1350℃, and the time is 10-20h.

9. A YAG / Yb:YAG / YAG composite laser-transparent ceramic obtained by the preparation method according to claim 1, characterized in that, In the YAG / Yb:YAG / YAG composite laser transparent ceramic, both YAG and Yb:YAG components are cubic isotropic structures with an average grain size of 2-10 μm, a relative density of ≥99.9%, and a Yb:YAG layer thickness of 50-250 μm. When the thickness of the YAG / Yb:YAG / YAG composite laser-transparent ceramic sample is 4.5-5.5 mm, the linear transmittance at a wavelength of 1030 nm is ≥80%.

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