Ultralow-temperature crystallization copper plating method for surface of micron ceramic particleTechnical Field
The invention discloses an ultralow-temperature crystallization copper plating method for the surfaces of micron ceramic particles, and belongs to the field of ceramic particle surface treatment.
Background
The ceramic particles have the characteristics of high strength, high hardness, high temperature resistance, friction and wear resistance, chemical corrosion resistance and the like. The surface of the ceramic particles is metallized by plating copper on the surface of the ceramic particles, and the ceramic particles can be widely applied to industries such as composite materials, wear-resistant materials, high-temperature resistant materials, antioxidation coatings and the like. The current surface treatment methods of ceramic particles mainly comprise an electroplating method and an electroless plating method. The electroplating method is to form a plating layer on the surface of particles through electrode reaction, but the waste water and the waste gas generated by electroplating can cause environmental pollution; the alloy plating layer after the chemical plating treatment has good uniformity, but the chemical plating usually needs to use noble metal for activation treatment, and also has the disadvantages of waste liquid discharge, high cost, complex waste liquid treatment process and the like.
Disclosure of Invention
The invention aims to provide an ultralow-temperature crystallization copper plating method for the surfaces of micron ceramic particles, which specifically comprises the following steps:
(1) Adding the pretreated ceramic particles and Cu (NO3)2) into ethanol and magnetically stirring for 30 minutes to obtain Cu (NO3)2 ethanol saturated mixed solution containing ceramic particles, wherein the mass of the pretreated ceramic particles is 15-20% of copper nitrate and 95-100% of ethanol.
(2) The mixed solution is placed into a low-temperature constant-temperature experimental box, the temperature is reduced to the ultralow temperature of minus 50 ℃ to minus 100 ℃, then magnetic stirring is carried out for 0.5 to 1h, the solubility of Cu (NO3)2 in ultralow-temperature ethanol is reduced, and the Cu is crystallized and separated out on the surface of ceramic particles, the mixed solution is filtered and separated at the ultralow temperature, and then the ceramic particles with the surfaces coated with Cu (NO3)2 film) are obtained in a normal-temperature environment, and the ceramic particles with the surfaces coated with CuO film are obtained after thermal decomposition.
Preferably, the ceramic particles coated with the CuO film on the surface of the ceramic particles are subjected to the reduction process: the ceramic particles with the CuO film coated on the surface are placed into a reduction tank of a high-efficiency CuO composite powder reduction device to be heated to 400-500 ℃, H2 is introduced into the reduction tank from an air inlet pipe at a flow rate of 4-7L/min, a power input device is started, the reduction tank is enabled to rotate at a rotation speed of 14-17 r/min, the powder is enabled to be fully contacted with H2, the ceramic particles with the Cu film coated on the surface are obtained after high-efficiency reduction for 1-2H, and generated waste gas is discharged through a ventilation net, a porous flange plate and an exhaust pipe.
Preferably, the ceramic particles of the present invention are one of TiB2、SiC、Al2O3、SiO2 and BN having a particle size of 1 to 100. Mu.m.
Preferably, the pretreatment of the ceramic particles is to add the ceramic particles into a solution of H2SO4 with the concentration of 20 percent, magnetically stir for 30 minutes, filter, repeatedly wash with deionized water to be neutral, and then place the mixture in a drying oven for heat preservation at 150 ℃ for 1 hour for later use.
Preferably, the thermal decomposition of the present invention is specifically: and heating the ceramic particles coated with the Cu (NO3)2 film on the surface to 300-500 ℃ for decomposition for 1-4h, so that Cu (NO3)2) on the surface of the ceramic particles is decomposed and converted into CuO, and the ceramic particles coated with the CuO film on the surface are obtained.
The principle of the invention is as follows:
1. ultralow temperature crystallization copper plating principle
The ultra-low temperature crystallization copper plating is performed by adding the pretreated ceramic particles and Cu (NO3)2) into ethanol (melting point-114.1 ℃) at room temperature to obtain Cu (NO3)2 ethanol saturated mixed solution) containing the ceramic particles, and FIG. 1 shows the measured solubility curve of Cu (NO3)2) in ultra-low temperature ethanol along with the temperature, as can be seen from FIG. 1, cu (NO3)2) has a large difference in solubility in ethanol at room temperature (20 ℃ -30 ℃) and-100 ℃, so Cu (NO3)2) is dissolved in ethanol at room temperature (20 ℃ -30 ℃) and the preferable cooling range is-50 ℃ -100 ℃.
The method comprises the steps of adding Cu (NO3)2) into normal-temperature ethanol containing ceramic particles to form saturated solution, reducing the temperature to be ultralow temperature of minus 50 ℃ to minus 100 ℃, reducing the solubility of Cu (NO3)2 in the ethanol, crystallizing and separating out the surface of the ceramic particles, then heating and decomposing the ceramic particles coated with Cu (NO3)2), putting the ceramic particles into the efficient CuO composite powder reduction device (figure 3), heating, introducing H2, rotating the ceramic particles, and fully contacting the powder with gas, so that the CuO is efficiently reduced to Cu., and the ultralow-temperature crystallization is realized by adopting normal-temperature Cu (NO3)2/ethanol saturated solution to coat Cu (NO3)2) on the surface of the ceramic particles through physical cooling, thereby saving Cu (NO3)2 raw materials and reducing the environmental pollution problem caused by waste liquid.
2. Copper coating layer thickness control principle
According to the mass of ceramic particles: copper nitrate mass: ethanol mass= (15-20): (95-100): 100 (NO3)2) and Cu (NO3)2) were added to ethanol, and by controlling the temperature of the Cu (NO3)2 ethanol saturated mixed solution containing the ceramic particles, the solubility of Cu (NO3)2) in ultra-low temperature ethanol was reduced, and thus Cu was crystallized out on the surface of the ceramic particles, according to fig. 1, cu (NO3)2 solubility in ultra-low temperature ethanol was changed according to the temperature profile and fitting formula (1), cu (NO3)2 solubility in ethanol RT:
(1) Wherein, T is the temperature, DEG C; solubility of RT—Cu(NO3)2 in ethanol at T ℃, g/100g ethanol.
Based on the difference between the solubilities of Cu (NO3)2 in ethanol at normal and ultra-low temperatures) in formula (1), cu (mass of precipitation M1 of NO3)2 on the surface of ceramic particles:
M1＝RT1-RT2 (2)
(2) Wherein, the mass of M1—Cu(NO3)2 precipitated on the surface of the ceramic particles, g/100g ethanol; solubility of RT1—Cu(NO3)2 in normal temperature ethanol, g/100g ethanol; solubility of RT2—Cu(NO3)2 in ultra-low temperature ethanol, g/100g ethanol.
Cu (mass M2 of NO3)2 decomposed into CuO by heating) can be obtained from the ratios of Cu (NO3)2 to CuO relative molecular mass in the chemical formula of CuO by heating of the formulae (2) and Cu (NO3)2:
M2＝0.42(RT1-RT2) (3)
(3) Wherein, the mass of M1—Cu(NO3)2 precipitated on the surface of the ceramic particles, g/100g ethanol; m2—Cu(NO3)2 is heated and decomposed into the mass of CuO, and g/100g of ethanol; solubility of RT1—Cu(NO3)2 in normal temperature ethanol, g/100g ethanol; solubility of RT2—Cu(NO3)2 in ultra-low temperature ethanol, g/100g ethanol.
According to formula (3) and the relative molecular mass ratio of CuO to Cu in the chemical formula of CuO through heating reduction in H2 atmosphere, the mass M3 of CuO through heating reduction to Cu can be obtained:
M3＝0.34(RT1-RT2) (4)
(4) Wherein M2—Cu(NO3)2 is heated and decomposed into the mass of CuO, g/100g of ethanol; m3 -CuO is heated and reduced to Cu mass, g/100g ethanol in H2 atmosphere; solubility of RT1—Cu(NO3)2 in normal temperature ethanol, g/100g ethanol; solubility of RT2—Cu(NO3)2 in ultra-low temperature ethanol, g/100g ethanol.
The calculation formula of the surface area of the ceramic particles can be obtained according to the density formula, the particle size and the mass of the ceramic particles:
(5) Wherein S is the surface area of the ceramic particles, cm2;ρ1 is the density of the ceramic particles, g/cm3; m-mass of ceramic particles, g/100g ethanol; r-particle size of ceramic particles, μm.
According to the mass of the ceramic particles: copper nitrate mass: ethanol mass= (15-20): (95-100): 100, and by combining the formulas (1), (2), (3), (4) and (5), cu (NO3)2, cuO, and Cu (7, 8) can be derived from the molecular mass of the reactants:
(6) In the formula (8) of the above,Cu (average thickness of NO3)2 coating, mum; average thickness of deltaCuO -CuO coating, mum; average thickness of deltaCu -Cu coating, mum; surface area of S-ceramic particles, precipitation mass of cm2;M1—Cu(NO3)2 on the surface of ceramic particles, g/100g ethanol, mass of M2—Cu(NO3)2 decomposed into CuO by heating, g/100g ethanol, mass of M3 -CuO reduced to Cu by heating in H2 atmosphere, g/100g ethanol, density of rho1 -ceramic particles, density of g/cm3;ρ2—Cu(NO3)2, density of rho2＝2.32g/cm3;ρ3 -CuO, density of rho3＝6.31g/cm3;ρ4 -Cu, density of rho4＝8.96g/cm3, mass of M-ceramic particles, g/100g ethanol, particle size of R-ceramic particles, mum; solubility of RT1—Cu(NO3)2 in ethanol at normal temperature, g/100g ethanol, solubility of RT2—Cu(NO3)2 in ethanol at ultra-low temperature, g/100g ethanol.
3. Cu (NO3)2) is heated to decompose and reduce, and the temperature and time are selected
At 170 ℃, cu (NO3)2 is easy to decompose when heated to 250 ℃ and is completely decomposed, if heated to above 600 ℃, part of CuO is converted into Cu2 O. The decomposition temperature is 300-500 ℃ and the decomposition time is 1-4h for completely decomposing Cu (NO3)2 into CuO) coated on the surface of ceramic particles.
As is clear from the change in the Gibbs free energy of CuO reduced to Cu by heating in H2 atmosphere (FIG. 2), gibbs free energy is negative in the range of 25℃to 850℃and thus the reduction reaction proceeds spontaneously. But when the temperature is lower than 400 ℃, the reduction time is longer and the efficiency is low, and by adopting the efficient CuO composite powder reduction device (shown in figure 3), the reduction temperature is 400-500 ℃ and the reduction time is 1-2h.
The invention has the beneficial effects that:
the ultra-low temperature crystallization adopts normal temperature Cu (NO3)2/ethanol saturated solution to coat Cu (NO3)2) on the surface of ceramic particles through physical cooling, then the Cu (NO3)2) on the surface of the ceramic particles is heated and decomposed into CuO, the CuO is put into the efficient CuO composite powder reduction device (figure 3) of the invention, H2 is introduced after heating and rotated, so that the powder is fully contacted with H2, cuO is efficiently reduced into Cu, and further copper coating on the surface of the ceramic particles is realized.
Drawings
FIG. 1 is a graph showing the solubility of Cu (NO3)2 in ultra-low temperature ethanol as a function of temperature).
FIG. 2 shows the Gibbs free energy change for reduction of CuO to Cu in an atmosphere of H2 at 25℃to 850 ℃.
FIG. 3 is a schematic diagram of an efficient CuO composite powder reduction apparatus.
In fig. 3: 1-a power input device; 2-an exhaust pipe; 3-an air inlet pipe; 4-a heating furnace; 5-a reduction device housing; 6, a sealing ring; 7-a porous flange cover; 8-a breathable net; 9-a reduction tank; 10-a first bevel gear; 11-a bearing; 12-sealing the bearing; 13-supporting frames; 14-ceramic particles coated with CuO film on the surface; 15-thermocouple; 16-a second bevel gear.
FIG. 4 is a flow chart of an ultralow temperature crystallization copper plating process for the surface of ceramic particles.
Detailed Description
The device used in the embodiment of the invention is shown in figure 3, and comprises a power input device 1, an exhaust pipe 2, an air inlet pipe 3, a heating furnace 4, a reduction device shell 5, a sealing ring 6, a porous flange cover 7, a ventilation net 8, a reduction tank 9, a first bevel gear 10, a bearing 11, a sealing bearing 12, a support frame 13, ceramic particles 14 with CuO films coated on the surface, a thermocouple 15 and a second bevel gear 16; an output shaft of the power input device 1 sequentially passes through the heating furnace 4 and the reduction device shell 5 to be connected with the first bevel gear 10, and the second bevel gear 16 is meshed with the first bevel gear 10; one side of the reduction pot 9 is provided with a rotating shaft, the other side is provided with an air inlet pipe interface, the rotating shaft and the air inlet pipe interface are fixed on a supporting frame 13 through a bearing 11, the air inlet pipe 3 is connected with the air inlet pipe interface, and a sealing ring 6 is arranged at the joint; the rotating shaft is connected with a second bevel gear 16, and a supporting frame 13 is arranged at the bottom of the reduction device shell 5; the top of the reduction tank 9 is provided with a ventilation net 8 and a porous flange cover 7, and the joint of the air inlet pipe is provided with a sealing bearing 12 and the ventilation net 8; the top of the heating furnace 4 is provided with an exhaust pipe 2, and the bottom of the heating furnace 4 is provided with a thermocouple 15; a sealing ring is arranged at the joint of the air inlet pipe 3 and the reduction device shell 5.
Example 1
The ultralow-temperature crystallization copper plating method for the surface of the micron TiB2 powder is characterized by comprising the following steps of:
(1) Pretreatment of raw materials: tiB2 powder with the grain size of 1 μm on the market is added into H2SO4 solution with the concentration of 20 percent, and is magnetically stirred for 30 minutes, repeatedly washed to be neutral by deionized water, and then placed in a drying oven for heat preservation for 1 hour at 150 ℃ for drying for standby.
(2) A mixed solution was obtained: according to the mass of TiB2 powder: the mass of the copper nitrate: mass of ethanol = 20:95:100, tiB2 powder and Cu (NO3)2) were added to ethanol at room temperature (20 ℃) and magnetically stirred for 20 minutes to give Cu (NO3)2 ethanol saturated mixed solution) containing TiB2 powder.
(3) And (3) Cu (NO3)2) coating TiB2 powder, namely placing the mixed solution obtained in the step (2) into a low-temperature constant-temperature experimental box, reducing the temperature to the ultralow temperature of-50 ℃, magnetically stirring for 1h, reducing the solubility of Cu (NO3)2) in ultralow-temperature ethanol, crystallizing and separating out the Cu on the surface of the TiB2 powder, filtering the mixed solution at the ultralow temperature, separating out TiB2 powder, and placing the TiB2 powder coated with a Cu (NO3)2 film) with the thickness of 0.46 mu m on the surface in a normal-temperature environment.
(4) CuO coated TiB2 powder: the TiB2 powder coated with the Cu (NO3)2 film) obtained in the step 3 is heated to 500 ℃ to decompose for 1 hour, so that Cu (NO3)2) on the surface of the TiB2 powder is decomposed and converted into CuO, and the TiB2 powder coated with the 0.07 mu m-thick CuO film on the surface is obtained.
(5) Cu coated TiB2 powder: the TiB2 powder coated with the CuO film obtained in the step 4 is placed into a reduction tank 9 of a high-efficiency CuO composite powder reduction device to be heated to 500 ℃, H2 is introduced into the reduction tank 9 from an air inlet pipe 3 at a flow rate of 7L/min, a power input device 1 is started to rotate at a rotation speed of 14r/min, the powder is fully contacted with H2, tiB2 powder coated with a Cu film with the thickness of 0.04 mu m is obtained after high-efficiency reduction for 1H, and the generated waste gas is discharged through an air-permeable net 8, a porous flange 7 and an exhaust pipe 2.
Example 2
The ultralow-temperature crystallization copper plating method for the surface of the micron SiC powder is characterized by comprising the following steps of:
(1) Pretreatment of raw materials: adding SiC powder with the grain diameter of 30 μm on the market into H2SO4 solution with the concentration of 20%, magnetically stirring for 30 minutes, repeatedly washing with deionized water to be neutral, and then placing in a drying oven for heat preservation at 150 ℃ for 1 hour for drying for later use.
(2) A mixed solution was obtained: according to the mass of the SiC powder: the mass of the copper nitrate: mass of ethanol = 18:97:100, siC powder and Cu (NO3)2) were added to ethanol at room temperature (23 ℃) and magnetically stirred for 20 minutes to obtain a Cu (NO3)2 ethanol saturated mixed solution) containing SiC powder.
(3) And (3) Cu (NO3)2) coating SiC powder, namely placing the mixed solution obtained in the step (2) into a low-temperature constant-temperature experimental box, reducing the temperature to the ultralow temperature of-65 ℃, magnetically stirring for 0.8h, reducing the solubility of Cu (NO3)2) in ultralow-temperature ethanol, crystallizing and separating out the Cu on the surface of the SiC powder, filtering the mixed solution at the ultralow temperature, separating out the SiC powder, and placing the SiC powder in a normal-temperature environment to obtain the SiC powder with the surface coated with Cu (NO3)2) film with the thickness of 16.6 mu m.
(4) CuO coated SiC powder: the SiC powder coated with Cu (NO3)2 film obtained in step 3 was heated to 435 ℃ for decomposition for 2 hours, so that Cu (NO3)2) on the surface of the SiC powder was decomposed and converted into CuO, and the SiC powder coated with a CuO film having a thickness of 2.6 μm on the surface was obtained.
(5) Cu coated SiC powder: the SiC powder coated with the CuO film obtained in the step 4 is placed into a reduction tank 9 of a high-efficiency CuO composite powder reduction device (shown in figure 3) to be heated to 475 ℃, H2 is introduced into the reduction tank 9 from an air inlet pipe 3 at a flow rate of 6L/min, a power input device 1 is started to rotate at a rotation speed of 15r/min, the powder is fully contacted with H2, the SiC powder coated with a Cu film with the thickness of 1.4 mu m on the surface is obtained after high-efficiency reduction for 1.3H, and the generated waste gas is discharged through an air-permeable net 8, a porous flange 7 and an exhaust pipe 2.
Example 3
The ultralow-temperature crystallization copper plating method for the surface of the micron SiO2 powder is characterized by comprising the following steps of:
(1) Pretreatment of raw materials: adding SiO2 powder with the grain diameter of 60 μm on the market into H2SO4 solution with the concentration of 20%, magnetically stirring for 30 minutes, repeatedly washing with deionized water to be neutral, and placing in a drying oven for heat preservation at 150 ℃ for 1 hour for drying for later use.
(2) A mixed solution was obtained: according to the mass of SiO2 powder: the mass of the copper nitrate: mass of ethanol = 17:98:100, siO2 powder and Cu (NO3)2) were added to ethanol at room temperature (27 ℃ C.) and magnetically stirred for 20 minutes to give Cu (NO3)2 ethanol saturated mixed solution) containing SiO2 powder.
(3) And (3) Cu (NO3)2 is coated with SiO2 powder, the mixed solution obtained in the step (2) is placed into a low-temperature constant-temperature experimental box, the temperature is reduced to the ultralow temperature of-85 ℃, and then magnetic stirring is carried out for 0.7h, so that the solubility of Cu (NO3)2 in ultralow-temperature ethanol is reduced, and the Cu is crystallized and separated out on the surface of SiO2 powder, thereby obtaining SiO2 powder with the surface coated with Cu (NO3)2 film) with the thickness of 32.5 mu m.
(4) CuO coated SiO2 powder: the SiO2 powder coated with Cu (NO3)2 film) obtained in step 3 was heated to 375 ℃ to decompose for 3 hours, so that Cu (NO3)2) on the surface of the SiO2 powder was decomposed and converted into CuO, to obtain SiO2 powder coated with a 5.0 μm thick CuO film on the surface.
(5) Cu-coated SiO2 powder: the SiO2 powder coated with the CuO film obtained in the step 4 is placed into a reduction tank 9 of a high-efficiency CuO composite powder reduction device (shown in figure 3) to be heated to 435 ℃, H2 is introduced into the reduction tank 9 from an air inlet pipe 3 at a flow rate of 5L/min, a power input device 1 is started to rotate at a rotating speed of 16r/min, the powder is fully contacted with H2, the SiO2 powder coated with a Cu film with the thickness of 2.8 mu m on the surface is obtained after high-efficiency reduction for 1.7H, and the generated waste gas is discharged through an air-permeable net 8, a porous flange 7 and an exhaust pipe 2.
Example 4
The ultralow-temperature crystallization copper plating method for the surface of micron BN powder is characterized by comprising the following steps of:
(1) Pretreatment of raw materials: adding commercial BN powder with the grain diameter of 100 mu m into a solution of H2SO4 with the concentration of 20 percent, magnetically stirring for 30 minutes, repeatedly washing with deionized water to be neutral, and then placing the neutral BN powder in a drying box for heat preservation at 150 ℃ for 1 hour for drying for later use.
(2) A mixed solution was obtained: according to the mass of BN powder: the mass of the copper nitrate: mass of ethanol = 15:100:100, BN powder and Cu (NO3)2) were added to ethanol at room temperature (30 ℃) and magnetically stirred for 20 minutes to obtain a Cu (NO3)2 ethanol saturated mixed solution) containing BN powder.
(3) Cu (NO3)2 coating BN powder) is carried out by placing the mixed solution obtained in the step 2 into a low-temperature constant-temperature experimental box, reducing the temperature to ultralow temperature of minus 100 ℃, magnetically stirring for 0.5h, reducing the solubility of Cu (NO3)2 in ultralow-temperature ethanol, crystallizing and separating out the surface of BN powder, filtering the mixed solution at ultralow temperature, separating out BN powder, and placing the BN powder in a normal-temperature environment to obtain BN powder with the surface coated with Cu (NO3)2) film with thickness of 77.6 mu m.
(4) CuO coats BN powder: the BN powder coated with Cu (NO3)2 film obtained in step 3 was heated to 300 ℃ to decompose for 4 hours, so that Cu (NO3)2) on the surface of the BN powder was decomposed and converted into CuO, to obtain BN powder coated with a CuO film having a thickness of 12.0 μm on the surface.
(5) Cu coated BN powder: the BN powder coated with the CuO film obtained in the step 4 is placed into a reduction tank 9 of a high-efficiency CuO composite powder reduction device (shown in figure 3) to be heated to 400 ℃, H2 is introduced into the reduction tank 9 from an air inlet pipe 3 at a flow rate of 4L/min, a power input device 1 is started to rotate at a rotating speed of 17r/min, the powder is fully contacted with H2, the BN powder coated with a 6.6 mu m thick Cu film on the surface is obtained after high-efficiency reduction for 2 hours, and the generated waste gas is discharged through an air-permeable net 8, a porous flange 7 and an exhaust pipe 2.