Method for preparing composite powder for laser 3D printing by sol coating method
Technical Field
The invention relates to a method for preparing composite powder for laser 3D printing by a sol coating method, and belongs to the technical field of composite powder preparation.
Background
The ceramic reinforced aluminum-based composite material combines excellent specific strength and specific rigidity of a metal matrix and excellent high-temperature mechanical property and wear resistance of a ceramic phase, and is widely applied to the fields of aerospace, automobile manufacturing, nuclear energy equipment and the like. With increasingly complex service conditions and more severe requirements on the performance and efficiency of structural members, structural materials must simultaneously meet various performance requirements, and the production and application of traditional composite materials are limited to a certain extent.
In the prior art, ceramic particles are selected from refractory metal borides, carbides, nitrides, silicides and sulfides, a plurality of reinforcement mixed reinforced metal matrix composite materials are prepared by a powder metallurgy technology, and the ceramic particles are formed in situ in a metal matrix of the composite reinforced material. It can also be prepared by introducing various nano-reinforcing particles such as Al during atomization powder preparation process2O3、SiC、TiB2、BN、AlN、SiO2、ZrB2、ZrO2The combination of two or more than two kinds of the components makes the atomization pulverization and the nano-particle strengthening completed synchronously, and the matrix and the nano-particle are metallurgically combined, thus realizing the preparation of the multiphase reinforced aluminum matrix composite powder. For laser additive manufacturing, the in-situ synthesis method is still limited to generate a single ceramic phase, and for the preparation of a two-phase composite material, an additional method is mostly adopted. Due to the higher phase interface mismatching degree of the added ceramic phase and the metal matrix and the inevitable stress concentration, the post-treatment cost is greatly increased, which is not beneficial to the rapid preparation of the two-phase composite material.
In addition, the TiB is prepared by combining traditional fusion casting and atomization2A method for reinforcing aluminium-based composite powders, based on the main principle of using a mixed fluoride salt (KBF)4+K2TiF6) Reaction method, in-situ self-producing TiB in aluminium melt2Reinforcing phase to produce TiB2Reinforcing aluminum-based composite material casting blank, and preparing TiB from the casting blank by an atomization method2A reinforced aluminum matrix composite powder. This method is due to KBF in the preparation process4It is decomposed at high temperature or quickly hydrolyzed by water vapor to generate a great amount of toxic smog and cause environmental pollution. In addition, the reinforcing phase in the aluminum matrix composite material prepared by the method is often larger in size and easy to agglomerate, and the improvement of the comprehensive performance of the composite material is not facilitated.
Disclosure of Invention
The invention aims at the problems that the double reinforced phases of the laser additive manufacturing composite material in the prior art can not be synthesized simultaneously and the prior TiB2The problem of the preparation method of the reinforced aluminum-based composite material powder is to provide a sol coating methodThe invention discloses a method for preparing composite powder for laser 3D printing, which is characterized in that a titanium dioxide precursor and a hydrolysis inhibitor react in deionized water by a sol-gel method to obtain TiO2Sol of TiO2The sol is evenly coated on the surface of the B powder to prepare TiO2Coating the composite powder with @ B, and adding TiO2And carrying out vacuum ball milling treatment on the @ B coated composite powder and the aluminum alloy powder to obtain the composite powder for laser 3D printing. The powder material prepared by the method is used for the laser additive manufacturing process, and TiO is used2B can be fully contacted and reacted in an AlSi10Mg alloy melt to generate TiB in situ2And B2O3A ceramic reinforcement; the method can improve the utilization rate of the aluminum alloy powder to laser, is beneficial to improving the comprehensive performance of the composite material, and does not generate substances which pollute the environment in the powder preparation process.
A method for preparing composite powder for laser 3D printing by a sol coating method comprises the following specific steps:
(1) slowly dropping a titanium dioxide precursor and a hydrolysis inhibitor into deionized water, uniformly mixing, adjusting the pH value of a system to 2-3 by using dilute nitric acid under the stirring condition, and stirring for reacting for 8-10 h to obtain TiO2Sol;
(2) adding pure B powder to TiO2Mixing the sol evenly to make TiO2Uniformly coating the sol on the surface of pure B powder, aging at room temperature, drying and grinding to obtain TiO2@ B coated composite powder;
(3) adding TiO into the mixture2And carrying out ball milling treatment on the @ B coated composite powder and aluminum alloy powder to obtain the composite powder for laser 3D printing.
The titanium dioxide precursor in the step (1) is titanate, and the titanate is ethyl titanate, propyl titanate or butyl titanate.
The hydrolysis inhibitor in the step (1) is a mixture of glacial acetic acid and absolute ethyl alcohol, the glacial acetic acid accounts for 10-20% of the total volume of the glacial acetic acid and the absolute ethyl alcohol, and the volume ratio of the titanium dioxide precursor to the hydrolysis inhibitor to the deionized water is 1:3.5: 2-1: 4: 2.
The pure B powder in the step (2) is amorphous powder, and the particle size of the pure B powder is 1 to E5μm,TiO2TiO in @ B coated composite powder2The mass ratio of B to B was 11: 5.
And (3) ageing at room temperature for 2-3 days.
Preferably, the grinding process in the step (2) is carried out in a horizontal or planetary ball mill, the ratio of stainless steel grinding balls to phi 5 to phi 10 is 2 to 1, the ball-to-material ratio is 10 to 1, the fixed rotation speed is 150-250 rpm, the ball milling is carried out for 20min each time, the suspension time is 10min, and the total grinding time is 3-4 h;
the aluminum alloy powder in the step (3) is spherical powder, the particle size of the aluminum alloy powder is 15-105 micrometers, and preferably, the particle size of the powder used in the selective laser melting process is 15-53 micrometers; the particle size of the powder used in the laser near-net forming process is 53-105 μm;
TiO in composite powder for laser 3D printing2The mass fraction of the @ B coated powder is 1-10%.
Further, the aluminum alloy powder is AlSi10Mg alloy powder, AlSi7Mg alloy powder or other aluminum alloy powder for laser additive manufacturing.
Furthermore, the AlSi10Mg alloy powder comprises, by mass, 9-11% of Si, 0.2-0.45% of Mg, less than or equal to 0.55% of Fe, less than or equal to 0.45% of Mn, less than or equal to 0.05% of Cu, less than or equal to 0.15% of Ti, less than or equal to 0.1% of Zn, less than or equal to 0.05% of Sn, and the balance of Al.
Further, the AlSi7Mg alloy powder comprises, by mass, 6.5-7.5% of Si, 0.25-0.45% of Mg, less than or equal to 0.5% of Fe, less than or equal to 0.35% of Mn, less than or equal to 0.2% of Cu, less than or equal to 0.25% of Ti, less than or equal to 0.3% of Zn, less than or equal to 0.01% of Sn, and the balance of Al;
preferably, in the ball milling process in the step (3), the ratio of stainless steel milling balls phi 5 to phi 10 is 3 to 1, the ball-material ratio is 5 to 1, the fixed rotation speed is 200-300 rpm, and the ball milling mixing time is 2-3 h;
the TiO is2The powder is anatase type TiO2Powder or rutile TiO2And (3) powder.
The reaction equation of the in-situ synthesis related to the invention is
In which the mole ratioThe ratio is n (TiO)
2) N (B) 3:10, molar mass ratio M (TiO)
2) M (B) 79.9:10.81, M (TiO) is determined as mass ratio of reactants according to the mass relation of substances, M is n.M
2):m(B)=11:5。
The composite powder prepared by the method is used for laser 3D printing of ceramic reinforced metal matrix composite material, TiO2The @ B coated composite powder can be subjected to in-situ chemical reaction under the action of laser beam, and can be used for simultaneously synthesizing two required reinforcing phases TiB2And B2O3And the content of the reinforcing phase can be accurately regulated and controlled according to the stoichiometric ratio of the chemical reaction.
Preparation principle of composite powder for laser 3D printing: titanate as TiO2The precursor of (1) and the mixed solution of glacial acetic acid and absolute ethyl alcohol are used as hydrolysis inhibitors, and a layer of TiO is coated on the surface of pure B particles by a chemical method (sol-gel method)2Gel film, and dispersing it uniformly in AlSi10Mg alloy powder to obtain composite powder for additive manufacturing, and prepared TiO2In the process of laser forming of the @ B coated composite powder particle, TiO on the surface2The gel film is burnt with B particles in an AlSi10Mg alloy melt to synthesize dual-enhanced-phase TiB2And B2O3。
The invention has the beneficial effects that:
(1) in the composite powder for laser 3D printing, TiO2The gel film is tightly coated on the surface of the pure B particles, the gel film and the pure B particles are fully contacted and do not react with AlSi10Mg melt in the laser processing process, and the pollution to a matrix phase is effectively reduced while the in-situ reaction rate is improved;
(2) the invention relates to TiO coated on the surface of B powder in composite powder for laser 3D printing2The gel film can greatly increase the absorption rate of a powder material system to infrared laser, thereby improving the utilization rate of the aluminum alloy powder to the laser and improving the fusion quality of the composite material;
(3) the method of the invention does not generate substances which pollute the environment all the time in the preparation process, and the prepared composite material has small reinforcing phase size, thereby being beneficial to improving the comprehensive performance of the composite material.
Drawings
FIG. 1 is a flow chart of a process for preparing composite powder for laser 3D printing;
fig. 2 is a microstructure morphology of an aluminum-based composite material prepared from the composite powder for laser 3D printing in example 1.
Detailed Description
The present invention is further described in detail below with reference to specific examples, which will assist those skilled in the art in further understanding the present invention, but are not intended to limit the present invention in any way. It should be noted that various modifications and improvements can be made without departing from the spirit of the invention and still fall within the scope of the invention.
Example 1: a method for preparing composite powder for laser 3D printing by a sol coating method (see figure 1) comprises the following specific steps:
(1) slowly dripping a titanium dioxide precursor (butyl titanate) and a hydrolysis inhibitor into deionized water, uniformly mixing, adjusting the pH value of a system to 2.5 by adopting dilute nitric acid under the condition of vigorous stirring, and stirring and reacting for 8 hours at the temperature of 50 ℃ to obtain yellow and transparent TiO2Sol; wherein the hydrolysis inhibitor is a mixture of glacial acetic acid and absolute ethyl alcohol, the glacial acetic acid accounts for 10% of the total volume of the glacial acetic acid and the absolute ethyl alcohol, and the volume ratio of the titanium dioxide precursor to the hydrolysis inhibitor to the deionized water is 1:4: 2;
(2) adding pure B powder to TiO2Mixing the sol evenly to make TiO2Uniformly coating the sol on the surface of pure B powder, aging at room temperature for 48h, drying at 80 deg.C, and grinding to obtain TiO2@ B coated composite powder; wherein the pure B powder is amorphous powder, has purity of not less than 99.99%, average particle diameter of 2 μm, and TiO2TiO in @ B coated composite powder2The mass ratio of the B to the B is 11: 5; the grinding process is carried out in a planetary ball mill, the ratio of stainless steel grinding balls phi 5 to phi 10 is 2 to 1, the ball-material ratio is 10 to 1, the fixed rotation speed is 250rpm, the ball milling is carried out for 20min every time, the grinding is suspended for 10min, the powder temperature is prevented from rising, and the total grinding time is 3 h;
(3) adding TiO into the mixture2The @ B coated composite powder and the AlSi10Mg alloy powder are placedPerforming ball milling treatment in a planetary ball mill to obtain composite powder for laser 3D printing; wherein the TiO in the composite powder for laser 3D printing2The mass fraction of the @ B coated composite powder was 1%, the AlSi10Mg alloy powder was a spherical powder having an average particle diameter of 33.5 μm, and in mass percentage, the AlSi10Mg alloy powder contained 9.87% Si, 0.3% Mg, 0.09% Fe, 0.036% Mn, 0.019% Cu, 0.014% Ti, 0.01% Zn, 0.01% Sn, and the balance Al; in the ball milling process, the ratio of stainless steel grinding balls phi 5 to phi 10 is 3 to 1, the ball-material ratio is 5 to 1, the fixed rotation speed is 200rpm, and the ball milling mixing time is 2 hours;
in this example, the composite powder for laser 3D printing is processed by laser to form in-situ authigenic reinforcing phase (TiB)2+B2O3) The mass content of (A) is 1%;
the microstructure and morphology of the ceramic reinforced metal matrix composite prepared from the composite powder by laser additive manufacturing in the embodiment is shown in fig. 2, and as can be seen from fig. 2, the composite powder generates fine needle-like TiB under the action of high-energy laser2And B2O3And (4) a reinforcing phase.
Example 2: a method for preparing composite powder for laser 3D printing by a sol coating method (see figure 1) comprises the following specific steps:
(1) slowly dripping a titanium dioxide precursor (ethyl titanate) and a hydrolysis inhibitor into deionized water, uniformly mixing, adjusting the pH value of a system to 2 by adopting dilute nitric acid under the condition of vigorous stirring, and stirring and reacting for 10 hours at the temperature of 60 ℃ to obtain yellow and transparent TiO2Sol; wherein the hydrolysis inhibitor is a mixture of glacial acetic acid and absolute ethyl alcohol, the glacial acetic acid accounts for 20% of the total volume of the glacial acetic acid and the absolute ethyl alcohol, and the volume ratio of the titanium dioxide precursor to the hydrolysis inhibitor to the deionized water is 1:3.5: 2;
(2) adding pure B powder to TiO2Mixing the sol evenly to make TiO2Uniformly coating the sol on the surface of pure B powder, aging at room temperature for 72h, drying at 80 deg.C, and grinding to obtain TiO2@ B coated composite powder; wherein the pure B powder is amorphous powder, has purity of not less than 99.99%, average particle diameter of 5 μm, and TiO content2@ B coated compositeTiO in powder2The mass ratio of the B to the B is 11: 5; the grinding process is carried out in a planetary ball mill, the ratio of stainless steel grinding balls phi 5 to phi 10 is 2 to 1, the ball-material ratio is 10 to 1, the fixed rotation speed is 250rpm, the ball milling is carried out for 20min every time, the grinding is suspended for 10min, the powder temperature is prevented from rising, and the total grinding time is 3 h;
(3) adding TiO into the mixture2Putting the @ B coated composite powder and AlSi7Mg alloy powder into a planetary ball mill for ball milling treatment to obtain composite powder for laser 3D printing; wherein the TiO in the composite powder for laser 3D printing2The mass fraction of the @ B-coated composite powder was 10%, the AlSi7Mg alloy powder was a spherical powder having an average particle diameter of 77.5 μm, and 6.97% by mass of Si, 0.35% by mass of Mg, 0.05% by mass of Fe, 0.025% by mass of Mn, 0.015% by mass of Cu, 0.015% by mass of Ti, 0.1% by mass of Zn, 0.01% by mass of Sn, and the balance of Al in the AlSi7Mg alloy powder; in the ball milling process, the ratio of stainless steel grinding balls phi 5 to phi 10 is 3 to 1, the ball-material ratio is 5 to 1, the fixed rotation speed is 200rpm, and the ball milling mixing time is 3 hours;
in this example, the composite powder for laser 3D printing is processed by laser to form in-situ authigenic reinforcing phase (TiB)2+B2O3) The mass content of (A) is 10%;
the microstructure morphology of the ceramic reinforced metal matrix composite prepared from the composite powder through laser additive in the embodiment can be known, and the composite powder generates fine acicular TiB under the action of high-energy laser2And B2O3And (4) a reinforcing phase.
Example 3: a method for preparing composite powder for laser 3D printing by a sol coating method (see figure 1) comprises the following specific steps:
(1) slowly dripping a titanium dioxide precursor (butyl titanate) and a hydrolysis inhibitor into deionized water, uniformly mixing, adjusting the pH value of a system to 3 by adopting dilute nitric acid under the condition of vigorous stirring, and stirring and reacting for 7 hours at the temperature of 55 ℃ to obtain yellow and transparent TiO2Sol; wherein the hydrolysis inhibitor is a mixture of glacial acetic acid and absolute ethyl alcohol, the glacial acetic acid accounts for 15% of the total volume of the glacial acetic acid and the absolute ethyl alcohol, and the volume ratio of the titanium dioxide precursor to the hydrolysis inhibitor to the deionized water is 1:3.7: 2;
(2) will be pureB powder addition to TiO2Mixing the sol evenly to make TiO2Uniformly coating the sol on the surface of pure B powder, aging at room temperature for 60h, drying at 80 deg.C, and grinding to obtain TiO2@ B coated composite powder; wherein the pure B powder is amorphous powder, has purity of not less than 99.99%, average particle diameter of 3 μm, and TiO content2TiO in @ B coated composite powder2The mass ratio of the B to the B is 11: 5; the grinding process is carried out in a planetary ball mill, the ratio of stainless steel grinding balls phi 5 to phi 10 is 2 to 1, the ball-material ratio is 10 to 1, the fixed rotation speed is 250rpm, the ball milling is carried out for 20min every time, the grinding is suspended for 10min, the powder temperature is prevented from rising, and the total grinding time is 3 h;
(3) adding TiO into the mixture2Putting the @ B coated composite powder and AlSi10Mg alloy powder into a planetary ball mill for ball milling treatment to obtain composite powder for laser 3D printing; wherein the TiO in the composite powder for laser 3D printing2The mass fraction of the @ B coated composite powder was 4%, the AlSi10Mg alloy powder was a spherical powder having an average particle diameter of 33.5 μm, and in mass percentage, the AlSi10Mg alloy powder contained 9.87% Si, 0.3% Mg, 0.09% Fe, 0.036% Mn, 0.019% Cu, 0.014% Ti, 0.01% Zn, 0.01% Sn, and the balance Al; in the ball milling process, the ratio of stainless steel grinding balls phi 5 to phi 10 is 3 to 1, the ball-material ratio is 5 to 1, the fixed rotation speed is 200rpm, and the ball milling mixing time is 3 hours;
in this example, the composite powder for laser 3D printing is processed by laser to form in-situ authigenic reinforcing phase (TiB)2+B2O3) The mass content of (A) is 4%;
the microstructure morphology of the ceramic reinforced metal matrix composite prepared from the composite powder through laser additive in the embodiment can be known, and the composite powder generates fine acicular TiB under the action of high-energy laser2And B2O3And (4) a reinforcing phase.
While particular embodiments of the present invention have been described, it is to be understood that the invention is not limited to the precise embodiments described, and that various changes and modifications may be effected therein by one skilled in the art within the scope of the appended claims and the scope of the invention is to be accorded the full scope of the claims.