Disclosure of Invention
The invention provides a method for preparing a diamond metal matrix composite material by a selective laser melting process, aiming at solving the problems of poor wettability of diamond and a matrix, a large number of pore defects and thermal erosion of diamond in the process of preparing the diamond metal matrix composite material by the existing selective laser melting process.
A method for preparing a diamond metal matrix composite by a selective laser melting process is carried out according to the following steps:
firstly, preparing the plated diamond powder:
plating a transition layer with the thickness of 0.1-10 mu m on the surface of the diamond powder by a plating process to obtain plated diamond powder;
secondly, mixing:
mechanically and uniformly mixing the plated diamond powder and metal powder to obtain mixed powder;
the volume ratio of the diamond powder to the metal powder after plating is 1 (0.8-3); the melting point of the metal powder is lower than 1500 ℃;
thirdly, selective laser melting molding:
in selective laser melting equipment, controlling the oxygen content to be lower than 0.1%, preheating a substrate to 20-200 ℃, carrying out laser forming by using mixed powder under the conditions that the laser power is 50-2000W, the scanning speed is 1-500 mm/s, the spot diameter is 0.2-5 mm, the substrate temperature is 20-200 ℃ and the single powder spreading thickness of the substrate is 0.1-0.4 mm, and finally stopping heating, and taking the formed composite material off the substrate after the substrate is cooled;
fourthly, sintering:
and sintering the formed composite material in a vacuum furnace or an atmosphere furnace to obtain the diamond metal-based composite material.
The invention has the beneficial effects that: 1) according to the invention, the outermost layer of the diamond is plated with the high-melting-point metal, so that the diamond is prevented from being directly irradiated by laser in the laser forming process, the damage and the thermal corrosion of the diamond are reduced, and meanwhile, the direct contact between the matrix melt and the diamond is avoided due to the existence of the refractory metal plating layer in the forming process, so that the wettability between the matrix melt and the reinforcement is improved.
2) The invention is suitable for preparing the composite material with the melting point of the matrix (metal powder) lower than 1500 ℃. Can realize the high-density diamond metal matrix composite material, and the density can reach more than 80 percent.
3) The invention utilizes the selective laser melting process to prepare the diamond metal matrix composite, and can test the preparation of the isomeric piece with low cost and short period of the diamond metal matrix composite.
The invention is used for a method for preparing a diamond metal matrix composite material by a selective laser melting process.
Detailed Description
The technical solution of the present invention is not limited to the specific embodiments listed below, and includes any combination of the specific embodiments.
The first embodiment is as follows: the method for preparing the diamond metal matrix composite material by the selective laser melting process is carried out according to the following steps:
firstly, preparing the plated diamond powder:
plating a transition layer with the thickness of 0.1-10 mu m on the surface of the diamond powder by a plating process to obtain plated diamond powder;
secondly, mixing:
mechanically and uniformly mixing the plated diamond powder and metal powder to obtain mixed powder;
the volume ratio of the diamond powder to the metal powder after plating is 1 (0.8-3); the melting point of the metal powder is lower than 1500 ℃;
thirdly, selective laser melting molding:
in selective laser melting equipment, controlling the oxygen content to be lower than 0.1%, preheating a substrate to 20-200 ℃, carrying out laser forming by using mixed powder under the conditions that the laser power is 50-2000W, the scanning speed is 1-500 mm/s, the spot diameter is 0.2-5 mm, the substrate temperature is 20-200 ℃ and the single powder spreading thickness of the substrate is 0.1-0.4 mm, and finally stopping heating, and taking the formed composite material off the substrate after the substrate is cooled;
fourthly, sintering:
and sintering the formed composite material in a vacuum furnace or an atmosphere furnace to obtain the diamond metal-based composite material.
The beneficial effects of the embodiment are as follows:
1) according to the embodiment, the outermost layer of the diamond is plated with the high-melting-point metal, so that the diamond is prevented from being directly irradiated by laser in the laser forming process, the damage and the heat corrosion of the diamond are reduced, and meanwhile, the direct contact between the matrix melt and the diamond is avoided due to the existence of the refractory metal plating layer in the forming process, so that the wettability between the matrix melt and the reinforcement is improved.
2) This embodiment is suitable for the preparation of composite materials with a matrix (metal powder) melting point below 1500 ℃. Can realize the high-density diamond metal matrix composite material, and the density can reach more than 80 percent.
3) The embodiment utilizes the selective laser melting process to prepare the diamond metal matrix composite, and can be used for testing the preparation of the isomeric piece with low cost and short period of the diamond metal matrix composite.
The second embodiment is as follows: the first difference between the present embodiment and the specific embodiment is: the transition layer in the first step is a single metal plating layer or an alloy plating layer of several metal substances of hafnium, niobium, tantalum, tungsten and molybdenum. The rest is the same as the first embodiment.
The third concrete implementation mode: this embodiment is different from the first or second embodiment in that: the plating process in the first step is physical vapor deposition, chemical plating or electroplating. The other is the same as in the first or second embodiment.
The fourth concrete implementation mode: the difference between this embodiment mode and one of the first to third embodiment modes is: when the transition layer is a tungsten layer, the preparation method specifically comprises the following steps: the plating target material is pure tungsten target material by magnetron sputtering, the temperature in the furnace is 700-900 ℃, and the plating time is 10-60 min. The others are the same as the first to third embodiments.
The fifth concrete implementation mode: the difference between this embodiment and one of the first to fourth embodiments is: the diamond powder in the step one is single crystal diamond powder; the grain diameter of the diamond powder in the step one is 20-400 microns. The rest is the same as the first to fourth embodiments.
The sixth specific implementation mode: the difference between this embodiment and the first to fifth embodiments is: the metal powder in the second step is one or more of pure aluminum, pure copper, aluminum alloy, copper alloy, stainless steel and nickel-based alloy powder; the grain diameter of the metal powder in the second step is 10-60 mu m. The other is the same as the first to the fifth embodiments.
The seventh embodiment: the present embodiment differs from the first or sixth embodiment in that: and the mechanical mixing in the step two is that the planet ball mill is used for mixing for 0.5 to 2 hours. The rest is the same as the first or sixth embodiment.
The specific implementation mode is eight: the present embodiment differs from one of the first to seventh embodiments in that: the substrate in the third step and the metal powder in the second step are made of the same material. The rest is the same as the first to seventh embodiments.
The specific implementation method nine: the present embodiment differs from the first to eighth embodiments in that: the laser forming in the third step is specifically carried out according to the following steps: the first layer scans for two periods, then each layer scans for one period, the scanning directions of the layers are in an orthogonal relation, and the overlapping rate of the scanning intervals is 0-50%. The other points are the same as those in the first to eighth embodiments.
The detailed implementation mode is ten: the present embodiment differs from one of the first to ninth embodiments in that: and in the fourth step, the formed composite material is placed in a vacuum furnace or an atmosphere furnace for sintering, and the method specifically comprises the following steps: when the metal powder is pure copper or copper alloy, the heat preservation time is 0.5-4 h under the condition that the temperature is 800-1050 ℃; when the metal powder is pure aluminum or aluminum alloy, the heat preservation time is 0.5 h-5 h under the condition that the temperature is 500 ℃ -640 ℃; when the metal powder is stainless steel, the heat preservation time is 0.5-5 h under the condition that the temperature is 1100-1300 ℃; when the metal powder is nickel-based alloy, the heat preservation time is 0.5-5 h under the condition that the temperature is 1100-1300 ℃. The other points are the same as those in the first to ninth embodiments.
The following examples were used to demonstrate the beneficial effects of the present invention:
the first embodiment is as follows:
a method for preparing a diamond metal matrix composite by a selective laser melting process is carried out according to the following steps:
firstly, preparing the plated diamond powder:
plating a transition layer with the thickness of 0.5-1.5 mu m on the surface of the diamond powder by a plating process to obtain plated diamond powder;
secondly, mixing:
mechanically and uniformly mixing the plated diamond powder and metal powder to obtain mixed powder;
the volume ratio of the diamond powder to the metal powder after plating is 1: 1.5;
thirdly, selective laser melting molding:
in selective laser melting equipment, introducing high-purity argon to ensure that the oxygen content in a forming cavity is lower than 0.1%, preheating a substrate to 200 ℃, carrying out laser forming on mixed powder according to a designed shape under the conditions that the laser power is 300W, the scanning speed is 50mm/s, the spot diameter is 0.3mm, the substrate temperature is 200 ℃ and the single powder laying thickness of the substrate is 0.25mm, and finally stopping heating, wherein after the substrate is cooled, the formed composite material is taken down from the substrate;
fourthly, sintering:
and (3) placing the formed composite material in a vacuum furnace, preserving the heat for 2 hours under the conditions that the vacuum degree is 1Pa and the temperature is 1000 ℃, and then cooling along with the furnace to obtain the diamond copper-based composite material.
The transition layer in the first step is a tungsten layer.
The plating process in the first step is magnetron sputtering, and is specifically carried out according to the following steps: the plating target material is pure tungsten target material, the temperature in the furnace is 800 ℃, and the plating time is 40 min.
The diamond powder in the step one is single crystal diamond powder.
The particle size of the diamond powder in the first step is 75 microns.
And the metal powder in the second step is pure copper powder.
And the particle size of the metal powder in the second step is 50 microns.
The substrate in the third step is pure copper.
And the mechanical mixing in the step two is that the planet ball mill is used for mixing for 30 min.
The laser forming according to the designed shape in the third step specifically comprises the following steps: the first layer is scanned for two periods, then each layer is scanned for one period, the scanning directions of the layers are orthogonal, the overlapping rate of the scanning intervals is 50%, and the cylindrical body with the diameter of 12mm multiplied by 10mm is formed.
Fig. 1 is a scanning electron microscope image of the diamond copper-based composite material prepared in the first embodiment, and it can be seen from the image that the diamond is complete in shape, no obvious hot firing phenomenon occurs, and no obvious pore exists when the diamond is wrapped by the matrix, indicating that the densification process is better.
The density of the diamond copper-based composite material prepared in the first embodiment is 81.2%.
Example two:
a method for preparing a diamond metal matrix composite by a selective laser melting process is carried out according to the following steps:
firstly, preparing the plated diamond powder:
plating a transition layer with the thickness of 0.3-0.8 mu m on the surface of the diamond powder by a plating process to obtain plated diamond powder;
secondly, mixing:
mechanically and uniformly mixing the plated diamond powder and metal powder to obtain mixed powder;
the volume ratio of the diamond powder to the metal powder after plating is 1: 1.2;
thirdly, selective laser melting molding:
in selective laser melting equipment, introducing high-purity argon to ensure that the oxygen content in a forming cavity is lower than 0.1%, preheating a substrate to 200 ℃, carrying out laser forming on the mixed powder according to a designed shape under the conditions that the laser power is 300W, the scanning speed is 15mm/s, the spot diameter is 0.5mm, the substrate temperature is 200 ℃ and the single powder laying thickness of the substrate is 0.12mm, and finally stopping heating, and taking the formed composite material off the substrate after the substrate is cooled;
fourthly, sintering:
and (3) putting the formed composite material into a vacuum furnace, preserving the heat for 2.5 hours under the conditions that the vacuum degree is 1Pa and the temperature is 1100 ℃, and then cooling along with the furnace to obtain the diamond/316L stainless steel composite material.
The transition layer in the first step is a molybdenum layer.
The plating process in the first step is magnetron sputtering, and is specifically carried out according to the following steps: the plating target material is pure molybdenum target material, the temperature in the furnace is 850 ℃, and the plating time is 60 min.
The diamond powder in the step one is single crystal diamond powder.
The particle size of the diamond powder in the first step is 100 microns.
And the metal powder in the second step is 316L stainless steel powder.
The particle size of the metal powder in the second step is 17-53 μm.
The substrate in step three is a 316L substrate.
And the mechanical mixing in the step two is that the planet ball mill is used for mixing for 30 min.
The laser forming according to the designed shape in the third step specifically comprises the following steps: scanning two periods in the first layer, scanning one period in each layer, scanning direction between layers in orthogonal relation, scanning interval overlapping rate of 50%, and forming shape of 10 × 10 × 10mm3The block of (1).
The density of the diamond/316L stainless steel composite material prepared in example two is 83.7%.