Background
Copper and copper-based composite materials are widely used as functional materials because of their good electrical conductivity, thermal conductivity, corrosion resistance, and excellent manufacturability and easy recovery. However, in general, copper-based conductive and heat-conductive composite materials have high electrical conductivity and low strength, and when the strength is increased, the electrical and thermal properties are lost. In order to improve the mechanical properties, especially the thermal stability, of the material while ensuring its electrical and thermal properties, an effective method is to use dispersion reinforcements (e.g., alumina particles) to strengthen the copper matrix.
Preparation of Al at present2O3The particle dispersion strengthening copper-based composite material mainly adopts a conventional powder metallurgy method, a mechanical alloying method, a sol-gel method and an internal oxidation method. The conventional powder metallurgy method has mature process, but the nanoscale Al is difficult to prepare by the conventional method2O3Powder, not realizing Al simultaneously2O3The particles are refined and distributed uniformly. Coarse Al2O3The particles can restrict Al2O3Cu complexThe performance of the composite material is improved. The grain size obtained by the mechanical alloying method is large, the production control is difficult, the sol-gel method process is easy to control, the performance of the prepared material is good, the material is still in the test stage at present, the internal oxidation method process is complex, the technical parameter difficulty is high, and the manufacturing cost is high.
The spray thermal decomposition prepares various metal salts into precursor solution according to the stoichiometric ratio required for preparing composite powder, the precursor solution is atomized by an atomizer and then is carried into a high-temperature reaction furnace by carrier gas, a series of physical and chemical processes of solvent evaporation, solute precipitation to form solid particles, particle drying, particle thermal decomposition, sintering and forming and the like are instantly completed in the reaction furnace, and finally ultrafine powder is formed. The raw materials are mixed in a solution state, so that the components can be uniformly distributed, the process is simple, the loss of the components is less, the stoichiometric ratio can be accurately controlled, and the method is particularly suitable for preparing multi-component composite powder. The micro powder is obtained by drying liquid drops suspended in the air, the particles are generally in a regular spherical shape, the particles are less agglomerated, subsequent washing and grinding are not needed, and the high purity and high activity of the product are ensured. The whole process is completed rapidly in short seconds, so that the liquid drop has no time for component segregation in the reaction process, and the uniformity of component distribution is further ensured.
Therefore, the invention adopts a method of combining spray pyrolysis and reduction calcination to prepare the aluminum oxide/copper composite reinforced phase.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides a method for preparing a nano alumina/copper composite reinforcing phase by spray pyrolysis.
A preparation method of a nano aluminum oxide/copper composite reinforced phase comprises the following specific steps:
(1) preparation of mixed solution of copper salt and aluminum salt: adding weighed copper salt and aluminum salt into a container filled with deionized water, and stirring to prepare a mixed solution of the copper salt and the aluminum salt at room temperature, wherein the molar concentration of the copper salt in the mixed solution is 0.001 mol/L-saturated concentration, and the molar concentration of the aluminum salt is 0.001 mol/L-saturated concentration;
(2) spray pyrolysis of copper salt/aluminum salt mixed solution: heating the tubular furnace to a certain temperature, pouring the mixed salt solution obtained in the step (1) into an atomizer, introducing small droplets generated by atomization into the tubular furnace for spray pyrolysis reaction, and collecting to obtain aluminum oxide/cuprous oxide composite powder;
(3) reduction and calcination of alumina/cuprous oxide: and (3) filling the composite powder obtained in the step (2) into a boat, then putting into a tube furnace, and reducing and calcining in a weak reducing atmosphere to obtain the aluminum oxide/copper composite reinforced phase.
In the step (1), the copper salt is one or more of copper acetate, copper nitrate, copper sulfate and copper chloride which are mixed according to any ratio, and the aluminum salt is one or more of aluminum nitrate, aluminum sulfate and aluminum chloride which are mixed according to any ratio.
Preferably, the stirring time in the step (1) of the invention is 30-120 min, and the concentrations of the copper salt and the aluminum salt are 0.01-1.0 mol/L respectively.
The copper salt/aluminum salt mixed solution spray pyrolysis reaction in the step (2) of the invention comprises the following specific processes: pouring the copper salt/aluminum salt mixed solution into an atomizer, wherein the power of the atomizer is 25-100W/L, when the temperature of the tube furnace is raised to 600-750 ℃, starting the atomization mode of the atomizer, the copper salt/aluminum salt mixed solution is subjected to evaporation and drying together in a low-temperature region, and then the copper salt/aluminum salt solution is subjected to thermal decomposition in a high-temperature region to generate nano cuprous oxide and aluminum oxide, (wherein the high-temperature region is a heating region, and the low-temperature region is a heat conduction region).
The weak reducing atmosphere in the step (3) of the invention is as follows: the mixed gas of the inert atmosphere and hydrogen or nitric oxide is subjected to reduction calcination at 950-1250 ℃ for 0.5-4.0 h.
The invention has the beneficial effects that:
(1) the aluminum oxide/copper composite reinforced phase prepared by the method has a nanoscale size, and the copper and the aluminum oxide are uniformly dispersed, wherein the molar ratio of the aluminum oxide to the copper can be regulated and controlled by adjusting the concentration of the solution.
(2) The aluminum oxide/copper composite reinforced phase prepared by the method fully utilizes the characteristic of spray pyrolysis, the copper salt/aluminum salt mixed solution is evaporated and dried in a low-temperature area, then the copper salt/aluminum salt mixed solution is thermally decomposed in a high-temperature area to generate nano aluminum oxide/cuprous oxide, the interface of the nano aluminum oxide/cuprous oxide and the interface of the nano aluminum oxide/cuprous oxide are tightly combined, and the aluminum oxide/cuprous oxide is reduced under the hydrogen condition to obtain the nano aluminum oxide/copper composite reinforced phase, thereby being beneficial to dispersion strengthening of a copper-based composite material and obtaining a better reinforcing effect.
(3) The method for preparing the aluminum oxide/copper composite reinforced phase has simple process, the composite reinforced phase is obtained by two steps of spray pyrolysis and reduction calcination, and the production efficiency is high.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments, but the scope of the present invention is not limited to the description.
Example 1
A preparation method of an aluminum oxide/copper composite reinforced phase comprises the following specific steps:
(1) preparing a mixed solution of copper acetate and aluminum nitrate: weighing 6.0 g of copper acetate, adding the copper acetate into a beaker filled with 3L of deionized water, then weighing 11.3g of aluminum nitrate, adding the aluminum nitrate into the beaker filled with 3L of deionized water of copper salt, and fully dissolving the aluminum nitrate by magnetic stirring for 30 min at room temperature to prepare a mixed solution of copper salt and aluminum salt; the concentration of the obtained copper salt and aluminum salt is 0.01 mol/L;
(2) spray pyrolysis of the mixed solution: pouring the mixed solution prepared in the step (1) into an atomizer, starting the atomizer in an atomization mode (the atomizer is positioned at one end of the tube furnace) when the tube furnace is heated and the temperature rises to 600 ℃, setting the power to be 75W, evaporating and drying liquid drops generated by the mixed solution of copper salt and aluminum salt through ultrasonic atomization in a low-temperature region, and then carrying out thermal decomposition on the mixed solution in a high-temperature region to obtain the aluminum oxide/cuprous oxide composite powder.
(3) Reducing the alumina/cuprous oxide composite powder; firstly, the composite powder obtained in the step (2) is loaded into a corundum boat, then the corundum boat loaded with the composite powder is placed into a corundum tube furnace, the tube furnace is vacuumized, when the vacuum degree in the tube furnace reaches 0.01 Pa, a vacuum pump is closed, high-purity argon containing 5.0 wt% of hydrogen is introduced, the temperature is raised to 950 ℃ by the heating tube furnace, and reduction is carried out for 4.0h, so that the aluminum oxide/copper composite enhanced phase is obtained.
The microstructure of the composite powder prepared in this example is shown in fig. 1-9, and SEM images show that the size of the powder is in the order of nanometers, the morphology of the powder is spherical, XRD results show that the composite powder mainly contains alumina and copper, no other impurities are present, and EDX shows that alumina is dispersed in a copper matrix very uniformly.
Example 2
A preparation method of an aluminum oxide/copper composite reinforced phase comprises the following specific steps:
(1) preparation of mixed solution of copper nitrate and aluminum nitrate: under the condition of stirring, firstly weighing 56 g of copper nitrate into a 3L deionized water beaker, then weighing 113 g of aluminum nitrate into the 3L deionized water beaker added with the copper salt, and stirring for 40 min by adopting magnetic force at room temperature to fully dissolve the aluminum nitrate to prepare a mixed solution of the copper salt and the aluminum salt. The concentrations of the obtained copper salt and aluminum salt solutions were both 0.1 mol/L.
(2) Spray pyrolysis of the mixed solution: pouring the mixed solution prepared in the step (1) into an atomizer, starting the atomization mode of the atomizer when the temperature of the tubular furnace is raised to 650 ℃, setting the power to be 150W, evaporating and drying liquid drops generated by ultrasonic atomization of the mixed solution of copper salt and aluminum salt in a low-temperature region, and then carrying out thermal decomposition on the mixed solution in a high-temperature region to obtain the aluminum oxide/cuprous oxide composite powder.
(3) Reducing the alumina/cuprous oxide composite powder; firstly, the composite powder obtained in the step (2) is loaded into a corundum boat, then the corundum boat loaded with the composite powder is placed into a corundum tube furnace, the tube furnace is vacuumized, when the vacuum degree in the tube furnace reaches 0.01 Pa, a vacuum pump is closed, high-purity nitrogen containing 5.0 wt% of hydrogen is introduced, the temperature is raised to 1050 ℃ by the heating tube furnace, and reduction is carried out for 1.0 h, so that the aluminum oxide/copper composite enhanced phase is obtained.
SEM analysis shows that the size of the powder is in nanometer order of magnitude, the morphology of the powder presents spherical characteristics, and EDX analysis shows that the aluminum oxide is dispersed in the copper matrix very uniformly.
Example 3
A preparation method of an aluminum oxide/copper composite reinforced phase comprises the following specific steps:
(1) preparation of a mixed solution of copper chloride and aluminum chloride: under the condition of stirring, firstly weighing copper chloride and then adding the copper chloride into a 3L deionized water beaker, then weighing aluminum chloride and adding the aluminum chloride into the 3L deionized water beaker added with the copper salt, and stirring the mixture at room temperature for 40 min by adopting magnetic force to fully dissolve the copper salt and the aluminum salt to prepare a mixed solution of the copper salt and the aluminum salt. The concentration of the obtained copper salt and aluminum salt solutions was 1.0 mol/L.
(2) Spray pyrolysis of the mixed solution: pouring the mixed solution prepared in the step (1) into an atomizer, starting the atomization mode of the atomizer when the temperature of the tubular furnace is raised to 650 ℃, setting the power to be 300W, evaporating and drying liquid drops generated by ultrasonic atomization of the mixed solution of copper salt and aluminum salt in a low-temperature region, and then carrying out thermal decomposition on the mixed solution in a high-temperature region to obtain the aluminum oxide/cuprous oxide composite powder.
(3) Reducing the alumina/cuprous oxide composite powder; firstly, the composite powder obtained in the step (2) is loaded into a corundum boat, then the corundum boat loaded with the composite powder is placed into a corundum tube furnace, the tube furnace is vacuumized, when the vacuum degree in the tube furnace reaches 0.01 Pa, a vacuum pump is closed, nitrogen containing 5.0 wt% of carbon monoxide is introduced, the temperature of the tube furnace is raised to 1250 ℃ and reduced for 0.5h, and the aluminum oxide/copper composite enhanced phase is obtained.
SEM analysis shows that the size of the powder is in nanometer order of magnitude, the morphology of the powder presents spherical characteristics, and EDX analysis shows that the aluminum oxide is dispersed in the copper matrix very uniformly.
Example 4
A preparation method of an aluminum oxide/copper composite reinforced phase comprises the following specific steps:
(1) preparation of a mixed solution of copper sulfate and aluminum sulfate: under the condition of stirring, firstly weighing copper sulfate and adding into a 3L deionized water beaker, then weighing 113 g of aluminum sulfate and adding into the 3L deionized water beaker added with the copper salt, and stirring for 60 min at room temperature by adopting magnetic force to fully dissolve the copper salt and the aluminum salt to prepare a mixed solution of the copper salt and the aluminum salt, wherein the concentration of the obtained copper salt and aluminum salt solution is 0.5 mol/L.
(2) Spray pyrolysis of the mixed solution: pouring the mixed solution prepared in the step (1) into an atomizer, starting the atomization mode of the atomizer when the temperature of the tubular furnace is raised to 650 ℃, setting the power to be 150W, evaporating and drying liquid drops generated by ultrasonic atomization of the mixed solution of copper salt and aluminum salt in a low-temperature region, and then carrying out thermal decomposition on the mixed solution in a high-temperature region to obtain the aluminum oxide/cuprous oxide composite powder.
(3) Reducing the alumina/cuprous oxide composite powder; firstly, the composite powder obtained in the step (2) is loaded into a corundum boat, then the corundum boat loaded with the composite powder is placed into a corundum tube furnace, the tube furnace is vacuumized, when the vacuum degree in the tube furnace reaches 0.01 Pa, a vacuum pump is closed, high-purity nitrogen containing 5.0 wt% of hydrogen is introduced, the temperature is raised to 1100 ℃ by the heating tube furnace, and reduction is carried out for 3.0 h, so that the aluminum oxide/copper composite enhanced phase is obtained.
SEM analysis shows that the size of the powder is in nanometer order of magnitude, the morphology of the powder presents spherical characteristics, and EDX analysis shows that the aluminum oxide is dispersed in the copper matrix very uniformly.
Example 5
A preparation method of an aluminum oxide/copper composite reinforced phase comprises the following specific steps:
(1) preparation of a mixed solution of copper sulfate and aluminum nitrate: under the condition of stirring, adding weighed copper nitrate into a deionized water beaker with 10L, weighing aluminum nitrate, adding into the deionized water beaker with 10L added with the copper salt, and stirring for 30 min by adopting magnetic force at room temperature to fully dissolve the copper nitrate and the aluminum salt to prepare a mixed solution of the copper salt and the aluminum salt; the concentration of the obtained copper salt and aluminum salt solution was 0.1 mol/L.
(2) Spray pyrolysis of the mixed solution: pouring the mixed solution prepared in the step (1) into an atomizer, starting the atomization mode of the atomizer when the temperature of the tubular furnace is raised to 650 ℃, setting the power to be 500W, evaporating and drying liquid drops generated by ultrasonic atomization of the mixed solution of copper salt and aluminum salt in a low-temperature region, and then carrying out thermal decomposition on the mixed solution in a high-temperature region to obtain the aluminum oxide/cuprous oxide composite powder.
(3) Reducing the alumina/cuprous oxide composite powder; firstly, the composite powder obtained in the step (2) is loaded into a corundum boat, then the corundum boat loaded with the composite powder is placed into a corundum tube furnace, the tube furnace is vacuumized, when the vacuum degree in the tube furnace reaches 0.01 Pa, a vacuum pump is closed, pure hydrogen is introduced, and the temperature is raised to 1050 ℃ by the heating tube furnace and reduced for 1.0 h to obtain the aluminum oxide/copper composite enhanced phase.
SEM analysis shows that the size of the powder is in nanometer order of magnitude, the morphology of the powder presents spherical characteristics, and EDX analysis shows that the aluminum oxide is dispersed in the copper matrix very uniformly.