A high-temperature conductive graphene solution and its preparation method

Abstract

This invention discloses a high-temperature conductive graphene solution and its preparation method, comprising the following components by weight: 1800-2000 parts of a dispersion containing 3-5 nm graphene quantum dots, wherein the quantum dot content is 5-10 wt%; 450-510 parts of tin dioxide with a particle size ≤0.2 μm; 15-20 parts of ammonium tungstate and 15-20 parts of lanthanum oxide; 30-40 parts of manganese chloride tetrahydrate, 20-30 parts of nickel chloride, and 20-30 parts of copper chloride; 8000-10000 parts of a solvent system, wherein deionized water ≤4000 parts, anhydrous ethanol ≤5000 parts, isopropanol ≤100 parts, and n-butanol ≤50 parts; 800-1000 parts of tri-n-butyltin hydride and 100-300 parts of citric acid. Due to the adoption of the above technical solutions, this application has achieved breakthroughs in the stability of conductive networks through quantum dot bridging mechanisms; the standard deviation of electron migration path length has been reduced from 1.2 μm to 0.08 μm; the heterojunction interface has been optimized and a Type-II band structure has been formed, resulting in an 82% reduction in contact resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nanocomposites for high-temperature electronic device manufacturing, and specifically provides a high-temperature conductive solution for graphene quantum dots (GQDs) interface bridging and ZrO2 / Y2O3 dual-phase stable structure synergistic effect, which realizes ±1% heating uniformity and more than 5000 hours of life in an 800-1200℃ environment. BACKGROUND

[0002] The existing high-temperature conductive graphene solution has the following core defects in technology and preparation process:

[0003] 1. Insufficient high-temperature oxidation and structural stability Graphene is prone to oxidation with oxygen in a high-temperature environment, generating graphene oxide (GO), which significantly reduces the conductivity. During the oxidation process, the decomposition of oxygen-containing functional groups (such as epoxy and carboxyl groups) releases gases such as CO, CO2, and H2O, causing interlayer expansion of graphene, forming bubbles or airbags. Even if the structure is partially restored through high-temperature treatment (such as carbonization and graphitization), the residual microfolds will still intensify phonon scattering, reducing thermal and electrical conductivity. In addition, the thermal decomposition or oxidation of the substrate material (such as polymers) at high temperatures will also damage the overall structural stability.

[0004] 2. Dispersion and interface bonding problems The van der Waals force and π-π stacking between graphene layers cause them to easily agglomerate in solution, especially after the solvent evaporates at high temperatures, forming a conductive path that is interrupted. Traditional dispersants (such as surfactants) may decompose at high temperatures, failing to maintain a stable dispersion state. In addition, the thermal expansion coefficients of the graphene coating and the substrate (such as metal and ceramic) do not match, and the interface stress accumulates at high temperatures, causing the coating to crack or fall off. For example, the interlayer pressure during carbonization can reach 40MPa, causing the structure of the film to be destroyed.

[0005] 3. Thermal stability of the carrier material limits The commonly used polymer carrier (such as epoxy resin) is prone to decomposition at high temperatures, affecting the durability of the conductive network. Inorganic binders (such as aluminum dihydrogen phosphate) are resistant to high temperatures (500-1000℃), but may introduce insulating phases, reducing the overall electrical conductivity. In addition, the thermal decomposition products of the carrier material may contaminate the graphene surface, further degrading the performance. SUMMARY

[0006] To solve the above technical problems, the present application provides a high-temperature conductive graphene solution and a preparation method thereof to solve the above technical defects.

[0007] To solve one of the above technical problems, the technical solution adopted is as follows:

[0008] The present application provides a high-temperature conductive graphene solution, which comprises the following components by mass:

[0009] Dispersed liquid containing 3-5 nm graphene quantum dots 1800-2000 parts, wherein the quantum dot content is 5-10 wt%; tin dioxide with particle size ≤0.2 μm 450-510 parts; ammonium tungstate 15-20 parts, lanthanum oxide 15-20 parts; manganese chloride tetrahydrate 30-40 parts, nickel chloride 20-30 parts, copper chloride 20-30 parts; solvent system 8000-10000 parts, wherein the deionized water ≤4000 parts, anhydrous ethanol ≤5000 parts, isopropanol ≤100 parts, n-butanol ≤50 parts); tri-n-butyltin hydride 800-1000 parts, citric acid 100-300 parts.

[0010] In order to better achieve the purpose of the application, the application also has the following more optimal scheme implementation:

[0011] In some embodiments, the solvent system 8930 parts, wherein the deionized water 3900 parts, anhydrous ethanol 4900 parts, isopropanol 100 parts, n-butanol 30 parts;

[0012] In some embodiments, the tin dioxide is treated by gradient ball milling, and the process is: a) first section: 300 rpm ball milling for 24 hours, using Φ3mm zirconium oxide grinding beads;

[0013] b) second section: 1000 rpm ball milling for 12 hours, replacing Φ5mm grinding beads;

[0014] c) third section: 2000 rpm ball milling for 12 hours, replacing Φ8mm grinding beads.

[0015] Another object of the application is to provide the preparation method of the high-temperature conductive graphene ink as described above, comprising the following steps:

[0016] (1) phase separation preparation:

[0017] Solution A: After mixing graphene dispersion, deionized water, copper chloride and anhydrous ethanol, add tin dioxide at 60°C;

[0018] Solution B: Mix anhydrous ethanol, ammonium tungstate, nickel chloride, manganese chloride tetrahydrate at 80°C, and add indium oxide and tri-n-butyltin hydride under nitrogen;

[0019] (2) Gradient mixing: Solution B is added to solution A at a rate of 0.8-1.2 mL / min, and the stirring speed is

[0020] 700-900 rpm;

[0021] (3) Performance control: add citric acid to pH=3.4-3.6, and then add n-butanol;

[0022] (4) curing treatment: 60±2℃ for 24 hours, heating rate 2±0.5℃ / min.

[0023] In some embodiments, the solution after mixing in step (2) has a transmittance of ≥90% at 600 nm and a Zeta potential of ≤-35 mV.

[0024] In some embodiments, the high-temperature conductive graphene ink is used in the manufacture of high-temperature devices, including:

[0025] a) preheat the substrate to 750-850℃;

[0026] b) plasma spraying: pulse voltage 2500-3000V, argon pressure 0.5-0.8MPa, spraying time 10-50 seconds;

[0027] c) silk-screen silver electrode: silver content ≥80%, thickness 15-25μm;

[0028] d) step sintering: 150℃ / 5min→400℃ / 5min→750℃ / 10min.

[0029] In some embodiments, the plasma spraying is controlled by double signal triggering:

[0030] Signal 1: start spraying after the substrate is detected in place by an infrared sensor;

[0031] Signal 2: control the fluctuation range of the constant temperature system to ±10℃ by real-time temperature feedback.

[0032] Compared with the prior art, the above technical solutions have the following advantages: the stability of the conductive network breaks through the quantum dot bridging mechanism: 3-5nm GQDs fill the interlayer gap of graphene sheets (spacing ≈0.34nm), reducing the standard deviation of the electron migration path length from 1.2μm to 0.08μm (AFM line scan analysis); heterojunction interface optimization: SnO2(Eg=3.6eV) and graphene(Dirac point-4.5eV) form a Type-II energy band structure, reducing the contact resistance by 82%(Kelvin probe force microscopy test). DETAILED DESCRIPTION

[0033] The application will be further described in detail below in conjunction with the examples, which are only intended to provide a clearer understanding of the technical features, objectives and effects of the application.

[0034] The present application discloses a high-temperature conductive graphene ink, which comprises the following components by mass:

[0035] A dispersion liquid containing 3-5 nm graphene quantum dots 1800 parts, the quantum dot content in which is 5wt%; tin dioxide with a particle size of ≤0.2 μm 450 parts; ammonium tungstate 15 parts, lanthanum oxide 15 parts; manganese chloride tetrahydrate 30 parts, nickel chloride 20 parts, copper chloride 20 parts; solvent system 8930 parts, deionized water 3900 parts, anhydrous ethanol 4900 parts, isopropyl alcohol 100 parts, n-butanol 30 parts; tri-n-butyltin hydride 800 parts, citric acid 100 parts.

[0036] In some embodiments: it can also be a dispersion liquid containing 3-5 nm graphene quantum dots 2000 parts, the quantum dot content in which is 10wt%; tin dioxide with a particle size of ≤0.2 μm 510 parts; ammonium tungstate 20 parts, lanthanum oxide 20 parts; manganese chloride tetrahydrate 40 parts, nickel chloride 30 parts, copper chloride 30 parts; solvent system 10000 parts, deionized water 4450 parts, anhydrous ethanol 5410 parts, isopropyl alcohol 90 parts, n-butanol 50 parts; tri-n-butyltin hydride 1000 parts, citric acid 300 parts.

[0037] The tin dioxide is treated by gradient ball milling, and the process is as follows:

[0038] a) First section: 300 rpm ball milling for 24 hours, using Φ3mm zirconium oxide grinding beads;

[0039] b) Second section: 1000 rpm ball milling for 12 hours, replacing Φ5mm grinding beads;

[0040] c) Third section: 2000 rpm ball milling for 12 hours, replacing Φ8mm grinding beads.

[0041] The preparation method of the high-temperature conductive graphene ink of the application comprises the following steps:

[0042] (1) Phase separation preparation:

[0043] Solution A: After mixing graphene dispersion liquid, deionized water, copper chloride and anhydrous ethanol, tin dioxide is added and treated at 60℃;

[0044] Solution B: Anhydrous ethanol, ammonium tungstate, nickel chloride, manganese chloride tetrahydrate are mixed at 80℃, and indium oxide and tri-n-butyltin hydride are added under nitrogen;

[0045] (2) Gradient mixing: Solution B is added to Solution A at a rate of 0.8-1.2 mL / min, and the stirring speed is 700-900 rpm;

[0046] 700-900 rpm;

[0047] (3) Performance regulation: citric acid is added dropwise to pH=3.4-3.6, and n-butanol is further added;

[0048] (4) Curing treatment: 60±2℃ for 24 hours, heating rate 2±0.5℃ / min.

[0049] In some embodiments, the solution after mixing in step (2) has a transmittance of ≥90% at 600 nm and a Zeta potential of ≤-35 mV.

[0050] In some embodiments, the high-temperature conductive graphene solution is used in the manufacture of high-temperature devices, including:

[0051] a) Preheat the substrate to 750-850℃;

[0052] b) Plasma spraying: pulse voltage 2500-3000V, argon pressure 0.5-0.8MPa, spraying time 10-50 seconds;

[0053] c) Screen-printed silver electrode: silver content ≥80%, thickness 15-25μm;

[0054] d) Step sintering: 150℃ / 5min→400℃ / 5min→750℃ / 10min.

[0055] In some embodiments, the plasma spraying is controlled by double signal triggering:

[0056] Signal 1: Infrared sensor detects the substrate in place and starts spraying;

[0057] Signal 2: Real-time temperature feedback controls the fluctuation range of the constant temperature system within ±10℃.

[0058] In addition, in the formula system, the following table (mass percentage)

[0059] Components Dosage Functional mechanism and innovative design Graphene phase 15.2％ 3-5nm GQDs (5-8% of the proportion), quantum confinement effect bridging layer defects Solvent system 67.8％ Ethanol / isopropanol / n-butanol complex (surface tension 25±0.5mN / m) Conductive enhancer 5.0％ Sn02 / In203 heterojunction (0.7 eV conduction band offset, promotes electron tunneling) High-temperature stabilizer 0.3％ WO3-La2O3 core-shell structure Interface regulator 11.7％ Mn 2+ -π bond coordination energy - 2.3 eV

[0060] The key control points of the process are: the solution B is added at a rate of 1mL / min (too fast flow rate leads to SnO2 agglomeration, particle size increases to >500nm); the solidification heating rate is 2℃ / min (rate >5℃ / min leads to phase separation, transmittance <80%).

[0061] In some embodiments, the graphene solution:

[0062] 1. Raw material: flake graphite (20 mesh, carbon content > 99.9%) 1 kg; equipment: UH750 ultrasonic high pressure homogenizer (maximum power 3000 W); process: 2 kg deionized water + 100 ml isopropanol, 2000 W variable frequency processing (20 kHz-1 MHz) 5 h→ add 10 ml 10 wt% CTAB solution→ 3000 rpm centrifugation for 30 min→ 0.22 μm ceramic membrane filtration; product index: flake diameter 1.2±0.3 μm, number of layers 3.2±0.8 layers, GQDs content 7.3 wt% (Raman ID / IG=0.08).

[0063] 2. Solution-water composite process

[0064] Solution A (conductive matrix phase):

[0065] Step 1: 2000 g graphene solution + 3900 g deionized water→ 40 kHz ultrasonic 10 min (deagglomeration);

[0066] Step 2: add 20 g CuCl2→ magnetic stirring 500 rpm / 30 s (form Cu 2+ coordination environment);

[0067] Step 3: add 4900 g anhydrous ethanol→ stir for 30 s;

[0068] Step 4: add 510 g ball-milled SnO2 (D50=0.18 μm)→ 60 °C water bath stirring for 15 min (transmittance 86%);

[0069] Step 5: add 100 g isopropanol→ stand for 30 min (complete sol-gel transition). Solution B (high-temperature stable phase):

[0070] Step 1: 1000 g ethanol + 20 g (NH4) 10 W 12 O 41 → stir for 30 s;

[0071] Step 2: add 30 g NiCl2→ stir for 60 s;

[0072] Step 3: add 40 g MnCl2·4H2O→ 80 °C stirring until the conductivity is stable (about 20 min);

[0073] Step 4: add 120 g In2O3+ 1000 g CH 12 H 28 Sn under nitrogen protection→ stir for 10 min;

[0074] Step 5: Add 20 g La2O3→ stir for 2 min (La2O3@WO3 core-shell structure is formed); Gradient mixing: solution B is added dropwise into solution A at 1 mL / min (800 rpm), and after dropping, stirring is continued for 25 min→ 250 g of citric acid is added dropwise to pH = 3.5 (Zeta potential -35 mV)→ 30 g of n-butanol is added and stirred for 1 min.

[0075] Plasma spray film forming

[0076]

[0077]

[0078] Performance verification:

[0079] Sheet resistance: 8.0 ± 0.2 Ω / □ (four-point probe method, 25°C);

[0080] 1000°C lifetime: 5120 hours (failure criteria: resistance increase > 20% or film peeling > 5% area); Film thickness uniformity: 201 ± 6 nm (CV = 2.98%, measured by white light interferometer).

[0081] In some embodiments, the plasma high-temperature plating can also be as follows:

[0082] 1. The prepared nanoscale liquid medicine is quantitatively filled into a high-temperature acid and alkali resistant medicine tank at 2000 ml per time, and the medicine tank filled with the medicine is inserted into a self-assembled plasma high-temperature plating machine. The power of the machine is turned on, the high-voltage output is switched to pulse output, the voltage output amplitude is about AC 2500-3000V, the current is about 1.2A, the spray gun gas pressure is adjusted to 0.8Mpa, the protective gas (argon) is adjusted to 0.6Mpa, the water cooling circulation system is turned on, the infrared object automatic sensing spraying is turned on, the plating area constant temperature system is turned on, to ensure that the workpiece is constant at about 800 degrees when the plating machine is working, and the workpiece reaches the sensing area after waiting for automatic spraying.

[0083] 2. Put the ceramic pot into the tunnel furnace and heat it to 800 degrees for 10 minutes. After 10 minutes, the ceramic pot or (pot) is sent to the spraying positioning work area through the ceramic roller conveyor belt. The infrared automatic sensor of the plasma high-temperature plating machine outputs two signals after sensing that the workpiece is in place. Signal 1 triggers the plasma high-temperature plating machine to start automatic spraying of the above-mentioned medicine for about 20 seconds (the spraying time is adjusted according to the actual demand of sheet resistance, about 10-50 seconds). Signal 2 triggers the plating area constant temperature system, which keeps the workpiece constant at about 800 degrees during plating. After plating is completed, the ceramic roller conveyor belt transports the object to the high-pressure cooling area for cooling. The infrared temperature measurement system detects that the object is below 40 degrees, and then transports the object to the silk screen printing work area.

[0084] 3、Silk screen area sensor after sensing the object to start automatic printing silver electrode (silver electrode silver content to reach 80% or more, thickness 20 silk around), the silk screen workpiece by conveyor belt to CLONG-2 type high temperature tunnel furnace sintering, sintering temperature curve as follows: 150 drying 5 minutes mainly to remove the solvent volatilization in silver paste, 400 degrees 5 minutes to remove the organic matter in silver paste decomposition, 750 sintering 10 minutes after completion, the object is sent to QC platform detection by conveyor belt.

Claims

1. A high temperature conductive graphene ink, characterized in that, The composition comprises the following components by mass fraction: A dispersion liquid containing 3-5 nm graphene quantum dots, 1800-2000 parts, wherein the content of the quantum dots is 5-10 wt%; Tin dioxide with a particle size of ≤0.2 μm, 450-510 parts; Ammonium tungstate, 15-20 parts, lanthanum oxide, 15-20 parts; Manganese chloride tetrahydrate, 30-40 parts, nickel chloride, 20-30 parts, and copper chloride, 20-30 parts; The solvent system comprises deionized water, ≤4000 parts, anhydrous ethanol, ≤5000 parts, isopropyl alcohol, ≤100 parts, and n-butanol, ≤50 parts; Indium oxide, a certain number of parts, tri-n-butyltin hydride, 800-1000 parts, and citric acid, 100-300 parts.

2. The high temperature conductive graphene ink of claim 1, wherein, The solvent system comprises 8930 parts, of which deionized water, 3900 parts, anhydrous ethanol, 4900 parts, isopropyl alcohol, 100 parts, and n-butanol, 30 parts.

3. The high temperature conductive graphene ink of claim 1, wherein: The tin dioxide is subjected to gradient ball milling treatment, and the process is as follows: a) First stage: 300 rpm ball milling for 24 hours, using Φ3 mm zirconia grinding beads; b) Second stage: 1000 rpm ball milling for 12 hours, replacing the grinding beads with Φ5 mm; c) Third stage: 2000 rpm ball milling for 12 hours, replacing the grinding beads with Φ8 mm.

4. A method of producing high temperature conductive graphene ink according to any preceding claim characterised in that The method comprises the following steps: (1) Phase separation preparation: Solution A: mixing the graphene dispersion liquid, deionized water, copper chloride, and anhydrous ethanol, and then adding tin dioxide and treating at 60°C; Solution B: mixing anhydrous ethanol, ammonium tungstate, nickel chloride, manganese chloride tetrahydrate at 80°C, and then adding indium oxide and tri-n-butyltin hydride under nitrogen; (2) Gradient mixing: Solution B is added to Solution A at a rate of 0.8-1.2 mL / min, and the stirring speed is 700-900 rpm; (3) Performance adjustment: adding citric acid to pH=3.4-3.6, and then adding n-butanol; (4) Curing treatment: curing at 60±2°C for 24 hours, and the temperature rising rate is 2±0.5°C / min. After mixing in step (2), the solution has a transmittance of ≥90% at 600 nm, and a Zeta potential of ≤-35 mV.

5. The method of claim 4, wherein: The method comprises the following steps:

6. Use of the high temperature conductive graphene ink according to claim 1 in the manufacture of high temperature devices, characterized in that a) Preheating the substrate to 750-850°C; b) Plasma spraying: pulse voltage 2500-3000 V, argon pressure 0.5-0.8 MPa, and spraying time 10-50 seconds; c) Silk-printing silver electrode: silver content ≥80%, and thickness 15-25 μm; d) Staged sintering: 150°C / 5 min → 400°C / 5 min → 750°C / 10 min. The plasma spraying is controlled by double signal triggering:

7. Use according to claim 6, characterized in that: Signal 1: the infrared sensor detects that the substrate is in place, and then starts the spraying; Signal 2: the fluctuation range of the constant temperature system is controlled within ±10°C by real-time temperature feedback control. ​

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