CN114101693A

CN114101693A - Low-oxygen europium nickel powder for 3D printing and preparation method thereof

Info

Publication number: CN114101693A
Application number: CN202010898639.1A
Authority: CN
Inventors: 王凯先; 杨帆; 林文雄; 薛丽燕; 张雪松; 邵志恒
Original assignee: Xiamen Institute of Rare Earth Materials
Current assignee: Xiamen Institute of Rare Earth Materials
Priority date: 2020-08-31
Filing date: 2020-08-31
Publication date: 2022-03-01

Abstract

The invention discloses a low-oxygen europium-nickel powder for 3D printing and a preparation method thereof, comprising the following steps: S1. Weighing equal-quality raw metal europium and nickel, placing them in a vacuum suspension smelting furnace, and smelting the vacuum suspension smelting The furnace is evacuated and argon gas is introduced; S2, in the cooling water circulation state, increase the current to melt the metal raw material, reduce the current to cool the metal melt, repeat the above steps for remelting, and obtain a low-oxygen europium-nickel alloy ingot; S3, the The low-oxygen europium-nickel alloy ingot is cut into small squares, crushed and roughly ground into powder, and then plasma gas atomized to obtain spherical powder. The invention adopts the vacuum suspension smelting process to prepare the low-oxygen europium-nickel powder, and can control the oxygen content and element segregation in the alloy smelting process by maintaining the vacuum and argon state during the whole smelting process, and at the same time, plasma atomization is used to obtain Europium-nickel powder with excellent physical and mechanical properties and high spheroidization rate can be used for 3D printing to obtain high-precision products.

Description

Low-oxygen europium nickel powder for 3D printing and preparation method thereof

Technical Field

The invention belongs to the technical field of rare earth alloys, and particularly relates to low-oxygen europium nickel powder for 3D printing and a preparation method thereof.

Background

The 3D printing has high requirements on the form and performance of the used material, the material is generally spherical powder, the spheroidization rate is higher than 98%, and the high spheroidization rate can ensure the uniformity of the printed powder and subsequent printing. At present, the preparation technology of domestic high-end spherical metal powder is not mature enough, and the problems of overhigh oxygen content in metal raw materials for preparing powder and the like exist, generally, the oxygen content is controlled to be below 0.15 percent (mass fraction), and the ductility and fracture toughness of a printed product are seriously damaged due to overhigh oxygen content. For example, the vacuum induction melting gas atomization and electrode induction melting gas atomization technologies are generally adopted for preparing spherical metal powder, the vacuum induction melting gas atomization has the problems of low electric energy conversion efficiency, high energy consumption and the like, and carbonization reaction is easy to occur when molten metal flows through a graphite material flow guide pipe at high temperature, so that the carbon content of the powder is increased, and the comprehensive performance of the powder is influenced; the electrode induction melting gas atomization technology has the problems that the liquid flow stability is not easy to control and the like, and meanwhile, the components of the electrode are analyzed due to uneven heating in the melting process, so that the components of the powder are uneven.

Therefore, there is an urgent need for a new method for preparing high spheroidization rate powder for 3D printing.

Disclosure of Invention

The invention aims to provide a low-oxygen europium nickel powder for 3D printing and a preparation method thereof, and the method can control the oxygen content and the element segregation in the whole alloy smelting process.

In order to achieve the above object, according to an aspect of the present invention, there is provided a method for preparing europium nickel powder having low oxygen content for 3D printing, comprising the steps of: s1, weighing equal-mass raw materials of europium and nickel, putting the raw materials into a clean vacuum suspension smelting furnace, vacuumizing a cavity of the vacuum suspension smelting furnace, and introducing argon for cleaning; s2, increasing current to melt the metal raw material under the cooling water circulation state, then reducing the current to cool the metal melt, repeating the steps to re-melt the cast ingot, and obtaining the low-oxygen europium nickel alloy cast ingot with equal mass ratio; and S3, cutting the low-oxygen europium nickel alloy cast ingot into small squares in a multi-line mode, crushing and roughly grinding the small squares to prepare coarse powder, and obtaining spherical powder through plasma gas atomization powder-making equipment.

According to the present invention, step S3 is followed by a step of surface treating the low-oxygen europium nickel alloy. Preferably, the surface treatment step includes sanding the surface of the low-oxygen europium nickel alloy to make the surface bright, and cleaning the surface with absolute ethyl alcohol after sanding.

According to the invention, the method also comprises a step of vacuum drying the low-oxygen europium nickel alloy after surface treatment, and the low-oxygen europium nickel alloy is placed into a vacuum drying oven with the vacuum degree of 3 Pa-5 Mpa and dried for 15-20 minutes at the temperature of 100-120 ℃.

According to the invention, the step of vacuumizing the chamber of the vacuum suspension smelting furnace and introducing argon for cleaning in the step S1 comprises the following steps: s11, opening the mechanical pump, roughing the valve, evacuating the air in the furnace, and reducing the pressure in the furnace to 10-20 Pa; s12, opening the front valve and the molecular pump, and allowing the rotation speed of the molecular pump to reach 25000-; s13, closing the rough pumping valve and opening the main pumping valve to reduce the pressure in the furnace to 5.7-7.7 x 10^-3Pa; and S14, closing the main extraction valve, introducing argon gas with half atmospheric pressure, and cleaning the furnace body.

According to the invention, said step S2 comprises: s21, opening a normal temperature water pump and a cooling water pump to ensure that cooling water circulates in the smelting process; s22, opening a power supply box, increasing the current to 15-20A, and starting to increase the current at the rate of 5-10A when the raw materials of europium and nickel turn red to melt the metal raw materials; and S23, after the metal raw materials of europium and nickel are completely melted, reducing the current at the speed of 10-20A, and slowly cooling the metal melt. Preferably, the metal europium and the metal nickel are heated and remelted for 2-3 times. Preferably, the raw materials of europium and nickel are both square blocks, the size is 7 mm-10 mm, and the purity is 99.999%.

Preferably, the electromagnetic stirrer is started to stir in the remelting process so as to ensure the uniformity of the alloy smelting process, and the stirring current of the electromagnetic stirrer is 4-5A.

According to the invention, after the metal melt is cooled, the circulating water is closed, the air release valve is opened to balance the internal pressure and the external pressure, and the furnace door is opened for sampling.

According to the invention, a high-frequency induction plasma generator is adopted to provide plasma of the plasma gas atomization powder making equipment, the working power is 30-80 kw, the argon working flow is 20-50 slpm, the argon protective gas flow is 20-120 splm, and the powder feeding efficiency is 50-90 g/min.

According to another aspect of the present invention, there is also provided a low-oxygen europium nickel powder for 3D printing, prepared by any one of the above methods.

The invention has the beneficial effects that:

the invention adopts the vacuum suspension smelting process to prepare the low-oxygen europium-nickel powder for 3D printing, and controls the oxygen content and the element segregation in the alloy smelting process by keeping the vacuum and argon states in the whole smelting process, so that the elements are uniformly distributed in the alloy, and the conditions that the element content in a certain area is extremely high and the element content in a certain area is extremely low are avoided. Europium-nickel powder with excellent physical and mechanical properties is prepared by adopting a plasma atomization technology subsequently, and the plasma atomization has the following advantages: the atomization efficiency is high, and the metal melting and atomization processes are carried out simultaneously; the whole process is protected by inert atmosphere, which is beneficial to obtaining high-purity powder; the atomizing gas has higher temperature, can delay the solidification of particles and fully spheroidize; the fine powder has high yield and almost no satellite balls; narrow particle size distribution range and the like, advanced preparation process, accurate parameters and capability of being used for 3D printing to obtain products with high precision.

Drawings

Fig. 1 is an ingot diagram of a low-oxygen europium nickel alloy for 3D printing prepared in example 1 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and embodiments. It should be emphasized that the specific embodiments described herein are merely illustrative of the invention, are some, not all, and therefore do not limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The invention provides a preparation method of low-oxygen europium nickel powder for 3D printing, which comprises the following steps:

s1, weighing raw materials of europium (Eu) and nickel (Ni) with equal mass, putting the raw materials into a clean vacuum suspension smelting furnace, vacuumizing a cavity of the vacuum suspension smelting furnace, and introducing argon for cleaning. Preferably, the raw materials of europium and nickel are both square blocks, the size is 7 mm-10 mm, and the purity is 99.999%. The step S1 of vacuumizing the chamber of the vacuum suspension smelting furnace and introducing argon for cleaning comprises the following steps: s11, opening the mechanical pump, roughing the valve, evacuating the air in the furnace, and reducing the pressure in the furnace to 10-20 Pa; s12, opening the front valve and the molecular pump, and allowing the rotation speed of the molecular pump to reach 25000-; s13, closing the rough pumping valve and opening the main pumping valve to reduce the pressure in the furnace to 5.7-7.7 x 10^-3Pa; and S14, closing the main extraction valve, introducing argon gas at about half atmospheric pressure, and cleaning the furnace body.

And S2, increasing current to melt the metal raw material in a cooling water circulation state, then reducing the current to cool the metal melt, repeating the steps to remelt the cast ingot, closing the circulating water after the metal melt is cooled, opening a vent valve to balance the internal pressure and the external pressure, and opening a furnace door to sample to obtain the low-oxygen europium nickel alloy cast ingot with equal mass ratio.

Specifically, step S2 includes: s21, opening a normal temperature water pump and a cooling water pump to ensure that cooling water circulates in the smelting process; s22, opening a power supply box, increasing the current to 15-20A, and starting to increase the current at the rate of 5-10A when the raw materials of europium and nickel turn red to melt the metal raw materials; and S23, after the metal raw materials of europium and nickel are completely melted, reducing the current at the speed of 10-20A, and slowly cooling the metal melt. Preferably, the metal europium and the metal nickel are heated and remelted for 2-3 times. And starting the electromagnetic stirrer to stir in the remelting process to ensure the uniformity of the alloy smelting process, wherein the stirring current of the electromagnetic stirrer is 4-5A.

And S3, cutting the low-oxygen europium nickel alloy cast ingot into small squares in a multi-line mode, crushing and roughly grinding the small squares to prepare coarse powder, and obtaining spherical powder through plasma gas atomization powder-making equipment. Preferably, a high-frequency induction plasma generator is adopted to provide plasma of the plasma gas atomization powder making equipment, the working power is 30-80 kw, the argon working flow is 20-50 slpm, the argon protective gas flow is 20-120 splm, and the powder feeding efficiency is 50-90 g/min. High-speed and high-temperature plasma gas emitted by the plasma nozzle is used as an atomizing medium, so that feeding, melting and atomizing of metal raw materials are completed in the same step, the sphericity of powder is guaranteed, and the method can be used for 3D printing.

According to the present invention, step S3 is followed by a step of surface treating the low-oxygen europium nickel alloy. The surface treatment step comprises: and (3) polishing the surface of the low-oxygen europium nickel alloy by using sand paper to ensure that the surface is bright, and cleaning by using absolute ethyl alcohol after polishing. And (3) drying the surface-treated low-oxygen europium nickel alloy in vacuum, putting the dried low-oxygen europium nickel alloy into a vacuum drying oven with the vacuum degree of 3 Pa-5 Mpa, and drying for 15-20 minutes at the temperature of 100-120 ℃.

According to another aspect of the present invention, there is also provided a low-oxygen europium nickel powder for 3D printing, which is prepared by any one of the above methods. Preferably, the low-oxygen europium nickel powder has the characteristics of high spheroidization rate and the like.

The vacuum suspension furnace technology adopted by the invention is based on the vacuum induction melting technology, and utilizes the electromagnetic suspension force to make the metal molten pool in the crucible be in a suspension or quasi-suspension state, thereby eliminating the interaction between the molten pool and the crucible and preparing the material with high purity, uniform components and accuracy. The invention adopts the vacuum suspension furnace technology and has the following advantages: 1) the crucible material does not pollute furnace burden, and strong electromagnetic stirring is realized in the smelting process; 2) the reaction with the crucible can not occur and the furnace charge is hardly burnt; 3) the method can reach higher smelting temperature, has good product quality, less waste products and high yield, and can greatly reduce the preparation cost of the material; 4) the leftover materials can still keep high purity and can be recycled; 5) the crucible burning loss can not occur, the service life of the crucible is long, and the oxygen content of the smelted ingot can be effectively controlled when the smelting is carried out under the high vacuum condition.

Plasma atomization refers to a technology of injecting solid particles into inert gas plasma, completely evaporating the solid particles under the action of high temperature of the plasma, existing in a steam form, and then rapidly cooling the solid particles by using a gas quenching cooling technology to rapidly condense, nucleate and grow saturated steam to form ultrafine powder. The plasma atomization process is a unique process for producing active metal spherical micro powder, and parts produced by the plasma atomization process have excellent physical and mechanical properties due to the fact that the plasma atomization powder is fine.

The technical scheme of the invention is further explained by combining specific examples.

Example 1

Step S1: 400g (7mm) of europium metal square blocks and 400g (7mm) of nickel metal square blocks are weighed as reaction raw materials, and the purity of the square blocks is 99.999 percent.

Step S2: and opening the vacuum suspension smelting furnace, cleaning slag or dust in the furnace body, and then cleaning with absolute ethyl alcohol. Putting the metal square blank into a crucible, closing a furnace door, opening a rough pumping valve of a mechanical pump, evacuating the air in the furnace to reduce the pressure in the furnace to 10Pa, opening a pre-valve and a molecular pump, closing the rough pumping valve after the rotating speed of the molecular pump reaches 27000r/min, and opening a main pumping valve to reduce the pressure in the furnace to 6.7 multiplied by 10^-3And Pa, closing the main pumping valve, introducing argon to clean the furnace body, and then opening a normal-temperature water pump and a cooling water pump to ensure the circulation of cooling water in the smelting process.

Step S3: and opening a power supply box, increasing the current to 20A, observing the condition of the metal square in the crucible, waiting for the metal square to turn red, increasing the current according to 10A each time so that the metal raw material starts to melt, and melting all the metal raw material along with the slow increase of the current. The current is reduced by 15A each time so that the metal melt in the crucible is slowly cooled down, during which the circulating water is always in operation. And remelting the ingot by the same method after the ingot is cooled, and repeating the step for 2-3 times. And closing circulating water, opening an air release valve to balance internal pressure and external pressure, opening a furnace door for sampling, and smelting to obtain the europium-nickel alloy with equal mass ratio. And (3) polishing the surface of the europium-nickel alloy by using sand paper to enable the surface of the europium-nickel alloy to be bright, cleaning the polished europium-nickel alloy by using absolute ethyl alcohol, and drying the surface-treated europium-nickel alloy in a vacuum drying oven at the temperature of 120 ℃ and the vacuum degree of 3Pa for 15 min.

Step S4: cutting the europium-nickel alloy ingot into small squares in equal mass ratio, crushing and coarsely grinding the small squares to prepare coarse powder. The method comprises the steps of enabling coarse powder to pass through plasma gas atomization powder making equipment to obtain spherical powder, enabling a high-frequency induction plasma generator to provide plasma, enabling the working power to be 50kw, the argon working flow to be 30slpm, enabling the flow of argon protective gas to be 90splm, enabling the powder feeding efficiency of the equipment to be 60g/min, obtaining metal powder with high spheroidization rate after ball milling treatment, and enabling the metal powder to be used for 3D printing.

Step S5: and (4) sending the spherical powder prepared in the step S4 into a 3D printing device, modeling through computer modeling software, and partitioning the built three-dimensional model into sections layer by layer. And leading the established model into 3D printing equipment, spraying powder onto a workbench, wherein the heating temperature of the workbench is 300 ℃, and gradually accumulating the powder sprayed onto the workbench due to the heating action until the product is printed.

The europium-nickel powder prepared in example 1 was tested for its oxygen content, which was 300ppm, using a glow discharge mass spectrometer.

The foregoing is only a preferred application of the present invention, and it should be noted that, for those skilled in the art, various modifications and improvements can be made without departing from the technical principle of the present invention, and these modifications and improvements should also be considered as the protection scope of the present invention.

Claims

1. a preparation method for the low-oxygen europium nickel powder for 3D printing, is characterized in that, comprises the following steps:

S1, take by weighing the raw material metal europium and nickel of equal quality, put into the vacuum suspension smelting furnace of cleaning up, vacuumize the chamber of described vacuum suspension smelting furnace and pass into argon to clean;

S2, in the cooling water circulation state, increase the current to melt the metal raw material, then reduce the current to cool the metal melt, repeat the above steps to remelt the ingot to obtain a low-oxygen europium-nickel alloy ingot of equal mass ratio;

S3. Multi-line cutting the low-oxygen europium-nickel alloy ingot into small squares, crushing and rough grinding to make coarse powder, and then obtaining spherical powder through a plasma gas atomization pulverizing equipment.

2 . The preparation method according to claim 1 , characterized in that, after the step S3 , the method further comprises the step of performing surface treatment on the low-oxygen europium-nickel alloy. 3 .

Preferably, the step of surface treatment includes polishing the surface of the low-oxygen europium-nickel alloy with sandpaper to make the surface bright, and cleaning with anhydrous ethanol after polishing.

3. preparation method according to claim 2 is characterized in that, also comprises the step of vacuum drying the described low-oxygen europium-nickel alloy after surface treatment, putting it into the vacuum drying oven that vacuum degree is 3Pa～5Mpa, Dry at 100°C to 120°C for 15 to 20 minutes.

4. The preparation method according to claim 1, wherein in the step S1, the steps of evacuating the chamber of the vacuum suspension smelting furnace and purging with argon gas include:

S11, open the mechanical pump, the rough pumping valve, and evacuate the air in the furnace, so that the pressure in the furnace is reduced to 10Pa-20Pa;

S12, open the pre-valve and molecular pump, and wait for the speed of the molecular pump to reach 25000-27000r/min;

S13, close the rough pumping valve and open the main pumping valve, so that the pressure in the furnace is reduced to 5.7～7.7×10 ^-3 Pa;

S14, the main suction valve is closed, and argon gas at half atmospheric pressure is introduced to clean the furnace body.

5. preparation method according to claim 1 and 2, is characterized in that, described step S2 comprises:

S21, turn on the normal temperature water pump and the cooling water pump to ensure that the cooling water circulates during the smelting process;

S22, turn on the power box, increase the current to 15A-20A, and when the raw metal europium and nickel turn red, start to increase the current at a rate of 5A-10A, so that the metal raw materials are melted;

S23, after the metal raw materials europium and nickel are all melted, the current is reduced at a rate of 10A-20A, so that the metal melt is slowly cooled.

Preferably, the metals europium and nickel are heated and remelted 2 to 3 times.

Preferably, the raw materials, europium and nickel, are both in square shape, with a size of 7 mm to 10 mm, and a purity of 99.999%.

6 . The preparation method according to claim 1 , wherein in the remelting process, an electromagnetic stirrer is turned on to stir to ensure the uniformity of the alloy melting process, and the stirring current of the electromagnetic stirrer is 4A～5A. 7 .

7 . The preparation method according to claim 1 , wherein after the metal melt is cooled, the circulating water is closed, the vent valve is opened, the internal and external pressures are balanced, and the furnace door is opened for sampling. 8 .

8 . The preparation method according to claim 1 , wherein a high-frequency induction plasma generator is used to provide the plasma of the plasma gas atomization pulverizing equipment, and the working power is 30kw～80kw, and the working flow of argon gas is 30kw to 80kw. 9 . It is 20slpm～50slpm, the flow rate of argon protective gas is 20splm～120splm, and the powder feeding efficiency is 50g/min～90g/min.

9 . A low-oxygen europium nickel powder for 3D printing, characterized in that it is prepared by the method according to any one of claims 1 to 8 .