Magnesium silicon nitride powder as well as preparation method and application thereof

Abstract

The invention relates to magnesium silicon nitride powder as well as a preparation method and application thereof, and belongs to the technical field of structural ceramic powder materials. The preparation method comprises the following steps: pinning silicon nitride powder into magnesium powder to form magnesium-based composite powder with a micro-nano composite structure on the surface; mixing the magnesium-based composite powder with a dispersing agent to obtain a reaction precursor; carrying out self-propagating synthesis reaction on the reaction precursor to obtain silicon magnesium nitride composite powder; and sequentially carrying out acid pickling treatment and calcination treatment on the silicon magnesium nitride composite powder to obtain the silicon magnesium nitride powder. The yield of the prepared magnesium silicon nitride is 95% or above, the oxygen content of the product is lower than 0.15 wt.%, and the particle size is controlled to be 1-2 microns and is uniformly distributed; the method is suitable for application of sintering aids of high-performance ceramics, refractory material components and reinforcement phases of metal-based composite materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of structural ceramic powder materials, and particularly relates to a silicon magnesium nitride powder, a preparation method and application thereof. BACKGROUND

[0002] As an important nitride ceramic material, silicon magnesium nitride has a wide application prospect in the fields of high-performance ceramic substrates, microelectronic packaging, heat-conducting substrates, refractory materials and metal matrix composite reinforcing phases due to its high thermal conductivity, excellent mechanical properties, stable chemical properties and good high-temperature stability. In recent years, with the development of electronic devices towards high power and high integration, higher requirements are put forward for the purity, particle size distribution, oxygen content and crystallinity of the silicon magnesium nitride powder.

[0003] In addition, the existing technology generally has problems of low reaction conversion rate, easy agglomeration of product particles, inaccurate oxygen content control and poor process repeatability, which restricts the application of silicon magnesium nitride in high-performance ceramics and electronic materials. SUMMARY

[0004] The present application provides a preparation method of high-quality silicon magnesium nitride powder with high reaction efficiency, controllable product morphology and composition, high purity and low oxygen content, aiming at the defects in the existing synthesis technology of silicon magnesium nitride powder.

[0005] The purpose of the present application can be achieved by the following technical solutions.

[0006] In a first aspect of the present application, a preparation method of silicon magnesium nitride powder is provided, comprising the following steps: pinning silicon nitride powder in magnesium powder to form magnesium-based composite powder with a micro-nano composite structure on the surface; mixing the magnesium-based composite powder with a dispersant to obtain a reaction precursor; performing self-propagating synthesis reaction on the reaction precursor to obtain silicon magnesium nitride composite powder, and sequentially performing acid washing treatment and calcination treatment on the silicon magnesium nitride composite powder to obtain the silicon magnesium nitride powder.

[0007] Preferably, the pinning mode comprises plasma ball milling; the atmosphere of the plasma ball milling is negative pressure inert atmosphere, the electric current is 60mA-80mA, the ball milling time is 1h-10h, the ball milling rotation speed is 1200rmp-1400rmp, and the ball-to-material ratio is (5-30):1.

[0008] The pinning step described in the application can simultaneously realize interface pinning and activation effect. The application utilizes the synergistic effect of plasma discharge and high-energy mechanical ball milling to realize continuous bombardment of high-energy electron flow on the surface of the powder under specific current (60 mA-80 mA), rotational speed (1200 rpm-1400 rpm), and ball-to-powder ratio (5-30):1, effectively removing the native oxide layer on the surface of the magnesium powder and exposing the high-activity metal surface. At the same time, the violent mechanical collision pins the nanoscale silicon nitride particles in the plastic matrix of the micron-sized magnesium powder, forming a firm micro-nano composite structure. This micro-nano composite structure greatly increases the contact area between the two phases and introduces a large number of lattice defects and strains, realizing the composite interface and high-activity state, so that the subsequent self-propagating reactants do not need to undergo long-range bulk diffusion, but only need to exchange atoms / ions in a short range, thereby significantly reducing the activation energy of the synthesis reaction, effectively inhibiting the volatilization of magnesium, and thus realizing high conversion rate and rapid reaction.

[0009] More preferably, the dispersant includes at least one of ammonium carbonate, ammonium bicarbonate, and ammonium chloride; the mixing method of the dispersant includes mechanical mixing or manual mixing; the rotational speed of the mechanical mixing is 30 rpm-250 rpm; and the mass ratio of the dispersant to the magnesium-based composite powder is (0.01-0.1):1.

[0010] The dispersant can achieve in-situ decomposition and physical isolation in the reaction system. Under the high-temperature conditions of the subsequent self-propagating synthesis reaction, the dispersant rapidly decomposes and releases gas, which escapes from the inside of the powder, thereby achieving in-situ pore formation. The formed pore structure not only can construct temporary gas channels and physical spacing between the reactant particles, promoting the full reaction of kilogram-level reactants, but also can effectively limit the excessive spreading and merging of the magnesium melt during the reaction process, avoiding the densification sintering of the powder. In addition, the porous structure is beneficial to the deep penetration of nitrogen to the reaction interface, and the reducing atmosphere created by the decomposition process helps to maintain a low oxygen partial pressure in the reaction area, thereby ensuring the high purity of the final product.

[0011] The molar ratio of the magnesium powder to the silicon nitride powder is (1-4):1; and / or, the silicon nitride includes α-Si3N4.

[0012] The self-propagating synthesis reaction is carried out in a nitrogen atmosphere or a nitrogen-hydrogen atmosphere, and the reaction pressure of the self-propagating synthesis reaction is 0.5 MPa-6 MPa. An igniter is used to start the reaction, and the igniter includes at least one of titanium powder, carbon powder, and magnesium powder.

[0013] Preferably, the silicon magnesium nitride composite powder is subjected to multi-step acid pickling, and the acid pickling treatment removes excess magnesium powder and oxides thereof; the calcination treatment is performed in a nitrogen atmosphere, the temperature of the calcination treatment is 800-1000°C, and the time of the calcination treatment is 1-4 hours.

[0014] The multi-step acid pickling process described in the present application can effectively dissolve by-products generated in the reaction, such as MgO and Mg2Si, etc.; the nitrogen atmosphere calcination process can remove trace amounts of adsorbed water and volatile impurities remaining in the powder and reduce the oxygen content; at the same time, effectively eliminate the internal stress generated by the rapid cooling of the self-propagating reaction, and improve the crystallinity of the product to achieve chemical stability and physical properties.

[0015] The particle size of the magnesium powder is 1-50 μm, and the particle size of the silicon nitride powder is 30-100 nm.

[0016] The micro-nano composite structure includes magnesium powder and silicon nitride powder, and the particles of the silicon nitride powder are pinned to the surface of the magnesium powder. In this way, a heterogeneous composite interface can be formed, and the interface bonding strength is high. In the present application, the particle size of the magnesium-based composite powder is 800 nm-30 μm.

[0017] In the second aspect of the present application, the present application provides a silicon magnesium nitride powder prepared by the method of the first aspect; the silicon magnesium nitride powder satisfies one or more of the following conditions: The particle size of the silicon magnesium nitride powder is 1-2 μm; Based on the total moles of the silicon magnesium nitride powder, the mole percentage of magnesium in the silicon magnesium nitride powder is 20-50%, and the mole percentage of silicon nitride in the silicon magnesium nitride powder is 50-80%; Based on the total mass of the silicon magnesium nitride powder, the mass percentage of oxygen in the silicon magnesium nitride powder is less than 0.15%; The yield of the silicon magnesium nitride is greater than or equal to 95%.

[0018] In the third aspect of the present application, the present application provides a use of the aforementioned silicon magnesium nitride powder in a sintering aid, a refractory material component, or a metal matrix composite reinforcement phase.

[0019] The beneficial effects of the high-yield silicon magnesium nitride powder preparation method of the present application include: (1) The micro-nano composite structure constructed by plasma ball milling greatly reduces the activation energy of the self-propagating reaction, improves the reaction conversion rate, and stabilizes the yield at more than 95%; (2) The decomposition of dispersant not only can be used for pore-forming, making the reaction proceed fully, but also can create a local reducing atmosphere, combined with subsequent pickling and nitrogen calcination, effectively removing impurities such as MgO, Mg2S and adsorbed water, so that the oxygen content of the final product is strictly controlled below 0.15wt.%; (3) The gas channels generated by the decomposition of dispersant prevent the excessive spreading of molten magnesium and the sintering agglomeration of particles, and the obtained magnesium silicon nitride powder has a narrow particle size distribution (1-2 μm) and excellent dispersibility. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a micro-morphology diagram of the magnesium silicon nitride powder prepared in Example 1.

[0021] Figure 2 is a micro-morphology diagram of the magnesium silicon nitride powder prepared in Example 2.

[0022] Figure 3 is a micro-morphology diagram of the magnesium silicon nitride powder prepared in Example 3.

[0023] Figure 4 is a micro-morphology diagram of the magnesium silicon nitride powder prepared in Example 4.

[0024] Figure 5 is an XRD diagram of the magnesium silicon nitride prepared in Example 1.

[0025] Figure 6 is an XRD diagram of the magnesium silicon nitride prepared in Example 2.

[0026] Figure 7 is an XRD diagram of the magnesium silicon nitride prepared in Example 3.

[0027] Figure 8 is an XRD diagram of the magnesium silicon nitride prepared in Example 4. DETAILED DESCRIPTION

[0028] Hereinafter, specific embodiments of the magnesium silicon nitride powder, its preparation method and application of the present application are disclosed in detail with appropriate reference to the accompanying drawings. However, there will be cases where unnecessary detailed description is omitted. For example, there are cases where detailed description of matters well known, repeated description of practically identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy, facilitating understanding by those skilled in the art. In addition, the accompanying drawings and the following description are provided in order for those skilled in the art to fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0029] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. The range defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range.

[0030] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0031] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0032] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0033] Existing technologies suffer from problems such as low purity, low yield, and difficulty in morphology control. Therefore, this application develops a method for preparing silicon magnesium nitride powder that is simple in process, has high reaction efficiency, high product purity, low oxygen content, excellent particle dispersibility, and is suitable for industrial production. The innovations are reflected in the raw material pretreatment, reaction interface design, atmosphere control, and post-treatment processes, which improve the overall performance of silicon magnesium nitride powder.

[0034] This application proposes a silicon-magnesium nitride powder, its preparation method, and its application through a self-propagating synthesis method after pretreatment of the powder. The preparation method of the silicon-magnesium nitride powder includes the following steps: Silicon nitride powder is embedded in magnesium powder to form magnesium-based composite powder with a micro-nano composite structure on the surface. The magnesium-based composite powder is mixed with a dispersant to obtain a reaction precursor; The reaction precursor undergoes a self-propagating synthesis reaction to obtain silicon magnesium nitride composite powder; the silicon magnesium nitride composite powder is then subjected to acid washing and calcination treatments to obtain the silicon magnesium nitride powder.

[0035] The pinning method includes plasma ball milling; the plasma ball milling atmosphere is a negative pressure inert atmosphere, the current is 60mA~80mA, the ball milling time is 1h~10h, the ball milling speed is 1200rpm~1400rpm, and the ball-to-material ratio is (5~30):1.

[0036] The dispersant includes at least one of ammonium carbonate, ammonium bicarbonate, and ammonium chloride; the dispersant is mixed by mechanical mixing or manual mixing, and the mechanical mixing speed is 30 rpm to 250 rpm.

[0037] The mass ratio of the dispersant to the magnesium-based composite powder is (0.01~0.1):1.

[0038] The molar ratio of magnesium powder to silicon nitride powder is (1~4):1; and / or, the silicon nitride is selected from α-Si3N4.

[0039] The self-propagating synthesis reaction is carried out in a nitrogen atmosphere or a nitrogen-hydrogen atmosphere, and the reaction pressure of the self-propagating synthesis reaction is independently 0.5 MPa to 6 MPa; the reaction is initiated by a pyrotechnic agent, which includes at least one of titanium powder, carbon powder, and magnesium powder.

[0040] The silicon-magnesium nitride composite powder is subjected to multi-step acid washing; the calcination treatment is carried out in a nitrogen atmosphere, the calcination temperature is 800℃~1000℃, and the calcination time is 1h~4h, thereby improving the crystallinity and releasing internal stress.

[0041] The magnesium powder has a particle size of 1μm to 50μm; the silicon nitride powder has a particle size of 30nm to 100nm.

[0042] The particle size of the magnesium-based composite powder is 800 nm to 30 μm.

[0043] Example 1: The raw materials for magnesium silicon nitride in this embodiment include: magnesium powder, silicon nitride powder, and ammonium chloride. The magnesium powder has a purity ≥99.5% and a particle size distribution of 20μm-50μm; the silicon nitride powder has an α-Si3N4 phase content ≥95%, a purity ≥99%, and a particle size distribution of 50nm-80nm. S1. The silicon nitride powder is pinned into the magnesium powder substrate to form a magnesium-based composite powder.

[0044] Take magnesium powder and silicon nitride powder with a molar ratio of 1.5:1 and add them to a plasma ball milling jar; evacuate the ball milling jar, then purge with nitrogen and evacuate again, repeating this process 2-3 times to create a nitrogen negative pressure environment inside the ball milling jar, which is conducive to plasma discharge; The ball milling process parameters were set as follows: discharge current 70mA, ball milling time 5h, ball milling speed 1300rpm, and silicon nitride milling ball to material mass ratio of 10:1.

[0045] After plasma ball milling, silicon nitride nanoparticles are embedded in the magnesium powder plastic matrix, forming magnesium-based composite powder with a micro-nano composite structure.

[0046] S2. The magnesium-based composite powder is uniformly mixed with the dispersant to obtain the reaction precursor powder.

[0047] Ammonium chloride, a dispersant, was added to the magnesium-based composite powder. The mass ratio of ammonium chloride to magnesium-based composite powder was 0.05:1.

[0048] The dispersant and magnesium-based composite powder were mixed uniformly for 60 minutes using a three-dimensional mixer (30 rpm) to obtain the reaction precursor powder.

[0049] S3. The reaction precursor undergoes a self-propagating synthesis reaction to obtain silicon magnesium nitride composite powder.

[0050] The precursor powder was loosely packed in a high-purity graphite crucible, with a loose packing density of 0.85 g / cm³. 3 .

[0051] Place the crucible in the self-propagating reaction apparatus, evacuate to 10 Pa, and then fill with high-purity nitrogen gas until the pressure is 1.0 MPa.

[0052] Titanium powder was used as an igniter, and a self-propagating synthesis reaction was initiated by igniting a tungsten wire coil. The ignition lasted for about 30 seconds, and after natural cooling, bulk silicon-magnesium nitride composite powder was obtained.

[0053] S4. The silicon nitride magnesium composite powder is subjected to acid washing and calcination treatment in sequence to obtain silicon nitride magnesium powder.

[0054] After the blocky magnesium silicon nitride composite powder was initially crushed by a crusher, it was subjected to a two-step acid washing with a 0.5 mol / L dilute hydrochloric acid solution. First, it was stirred at room temperature for 1 hour, and then stirred in a 60℃ water bath for 2 hours to fully remove the by-products MgO and Mg2Si.

[0055] After acid washing, the product was washed with deionized water until neutral, and then dried in a vacuum drying oven at 100°C for 12 hours.

[0056] The dried powder was then placed in a tube furnace and heated to 900°C at a rate of 5°C / min under a high-purity nitrogen atmosphere. The temperature was held for 2 hours, and then cooled to room temperature with the furnace at a rate of 3°C / min to obtain high-purity magnesium silicon nitride powder.

[0057] The silicon magnesium nitride powder prepared by the method in this embodiment has a grain size of 1μm-2μm. Figure 1 The purity is 99.85%, the yield is 96.42%, and the oxygen content is ≤0.08wt.% (the specific data of each indicator are shown in Table 1).

[0058] The magnesium silicon nitride powder obtained in Example 1 was subjected to XRD testing, and the XRD pattern is shown below. Figure 5 As shown.

[0059] Example 2: The reaction materials in this embodiment are the same as in Example 1, except that the dispersant used is ammonium carbonate. S1. In the same way as in Example 1, the silicon nitride powder is pinned into a magnesium powder substrate to form a magnesium-based composite powder.

[0060] S2. In the same manner as in Example 2, ammonium carbonate was used as a dispersant and uniformly mixed with magnesium-based composite powder to obtain a reaction precursor. The mass ratio of ammonium carbonate to magnesium-based composite powder was 0.08:1.

[0061] S3. The reaction precursor undergoes a self-propagating synthesis reaction to obtain silicon magnesium nitride composite powder.

[0062] The reaction precursor was loosely packed in a high-purity alumina crucible, with a loose packing density of 0.90 g / cm³. 3 .

[0063] Place the crucible in the self-propagating reaction apparatus, evacuate to 10 Pa, and then fill with high-purity nitrogen gas to a pressure of 3 MPa.

[0064] A mixture of carbon and magnesium powder was used as an igniter, and a self-propagating high-temperature synthesis reaction was initiated by igniting the mixture through a tungsten filament coil. The ignition lasted for about 30 seconds, and after natural cooling, bulk silicon-magnesium nitride composite powder was obtained.

[0065] S4. The silicon nitride magnesium composite powder was further acid-washed and calcined in the same manner as in Example 1 to obtain silicon nitride magnesium powder.

[0066] The silicon magnesium nitride powder prepared by the method in this embodiment has a grain size of 1.5μm-2μm. Figure 2 The purity is 99.89%, the yield is 95.11%, and the oxygen content is ≤0.12wt.% (the specific data of each indicator are shown in Table 1).

[0067] The silicon magnesium nitride powder obtained in Example 2 was subjected to XRD testing, and the XRD pattern is shown below. Figure 6 As shown.

[0068] Example 3: The silicon nitride magnesium raw material composition in this embodiment is the same as in Example 1; S1. In the same way as in Example 1, the silicon nitride powder is pinned into a magnesium powder substrate to form a magnesium-based composite powder.

[0069] S2. In the same manner as in Example 1, magnesium-based composite powder and dispersant are uniformly mixed to obtain a reaction precursor.

[0070] S3. The precursor powder undergoes a self-propagating synthesis reaction to obtain silicon magnesium nitride composite powder.

[0071] The reaction precursor was loosely packed in a high-purity graphite crucible with a loose packing density of 0.70 g / cm³.

[0072] Place the crucible in the self-propagating reaction apparatus, evacuate to 10 Pa, and then fill with high-purity nitrogen gas to a pressure of 6 MPa.

[0073] Titanium powder was used as an igniter, and ignition was initiated by passing an electric current through a tungsten filament coil, triggering a self-propagating reaction. The ignition lasted for about 30 seconds, and after natural cooling, bulk silicon-magnesium nitride composite powder was obtained.

[0074] S4. The silicon nitride magnesium composite powder is subjected to multi-step acid washing and calcination to obtain silicon nitride magnesium powder.

[0075] After the silicon-magnesium nitride composite product was crushed, a three-step acid washing process was adopted: first, it was treated with 0.5 mol / L dilute hydrochloric acid for 1 hour, then with 1 mol / L dilute nitric acid for 1 hour, and finally, it was lightly etched with HF-HCl mixture (volume ratio 1:10) for 30 minutes.

[0076] After pickling, wash with deionized water until neutral, and dry in a vacuum drying oven at 100°C for 12 hours.

[0077] The dried powder was then placed in a tube furnace and heated to 950°C at a rate of 3°C / min under a flowing high-purity nitrogen-hydrogen mixed atmosphere. The temperature was held for 4 hours and then cooled to room temperature with the furnace at a rate of 2°C / min to obtain ultra-high purity silicon magnesium nitride powder.

[0078] The silicon magnesium nitride powder prepared by the method in this embodiment has a grain size of 1.4μm-2μm. Figure 3 The purity is ≥99.97%, the yield reaches 94.5%, and the oxygen content is ≤0.04wt.% (the specific data of each indicator are shown in Table 1).

[0079] The silicon magnesium nitride powder obtained in Example 3 was subjected to XRD testing, and the XRD pattern is shown below. Figure 7 As shown.

[0080] Example 4: The reaction raw materials in this embodiment are the same as in Example 1, except that the dispersant used is ammonium bicarbonate. S1. The silicon nitride powder is pinned into the magnesium powder substrate to form a magnesium-based composite powder.

[0081] Magnesium powder and silicon nitride powder with a molar ratio of 2:1 were added to a plasma ball mill jar; the ball milling atmosphere was a negative pressure nitrogen environment; The ball milling process parameters are set as follows: discharge current 75mA, ball milling time 12h, ball milling speed 1400rpm, and ball-to-material ratio 20:1.

[0082] S2. Mix the magnesium-based composite powder with the dispersant evenly to obtain the reaction precursor powder.

[0083] Ammonium bicarbonate dispersant was added to the magnesium-based composite powder, and the mixture was mechanically mixed at low speed for 60 minutes. The mass ratio of ammonium bicarbonate to magnesium-based composite powder was 0.1:1.

[0084] S3. The precursor powder undergoes a self-propagating synthesis reaction to obtain silicon magnesium nitride composite powder.

[0085] The precursor powder was loosely packed in a high-purity graphite crucible with a loose packing density of 0.75 g / cm³.

[0086] Place the crucible in the self-propagating reaction apparatus, evacuate to 10 Pa, and then fill with a high-purity nitrogen-hydrogen mixed atmosphere to a pressure of 2.0 MPa.

[0087] Titanium powder is used as an igniter, and a self-propagating reaction is initiated by igniting a tungsten filament coil with electricity. Forced cooling is then performed using a copper anvil after the reaction.

[0088] S4. The silicon nitride magnesium composite powder is subjected to acid washing and calcination treatment to obtain silicon nitride magnesium powder. After crushing the silicon-magnesium nitride composite product, it was acid-washed in two steps with 0.5 mol / L dilute hydrochloric acid, washed with water and dried, and then calcined at 900℃ for 2 hours under a nitrogen atmosphere to obtain silicon-magnesium nitride powder.

[0089] The silicon magnesium nitride powder prepared by the method in this embodiment has a grain size of 1μm-2μm. Figure 4 The purity is ≥99.98%, the yield reaches 96.2%, and the oxygen content is ≤0.11 wt% (the specific data of each indicator are shown in Table 1).

[0090] The silicon magnesium nitride powder obtained in Example 4 was subjected to XRD testing, and the XRD pattern is shown below. Figure 8 As shown.

[0091] Comparative Example 1 The difference between this comparative example and Example 1 is that plasma ball milling is not used; instead, ordinary ball milling (ball-to-material ratio 10:1, rotation speed 500 rpm, time 10 h) is used to prepare the composite powder. The remaining steps are exactly the same as in Example 1.

[0092] The silicon magnesium nitride powder prepared by this comparative method had a yield of 70.2% and an oxygen content of 0.8 wt.%. The product had uneven particle size distribution and severe agglomeration.

[0093] Comparative Example 2 The difference between this comparative example and Example 1 is that no dispersant is added, and the precursor powder is pressed into shape (loose packing density > 1.5 g / cm³) for self-propagating reaction. The remaining steps are exactly the same as in Example 1.

[0094] The silicon magnesium nitride powder prepared by this comparative method is a hard block that is difficult to break. The yield is 78.5%, the oxygen content is 1.1 wt.%, and the particles are large and widely distributed after crushing.

[0095] Example 5 The difference between this embodiment and Embodiment 1 is that the calcination step is carried out in an air atmosphere and calcined at 800°C for 2 hours. The remaining steps are exactly the same as in Embodiment 1.

[0096] The silicon magnesium nitride powder prepared by the method in this embodiment is severely oxidized, with an oxygen content >8 wt.%, and phase analysis shows that a large amount of SiO2 and MgO are generated.

[0097] Example 6 The difference between this embodiment and Embodiment 1 is that the dispersant is replaced with inert silica nanoparticles (addition amount 5%), while the remaining steps are exactly the same as in Embodiment 1.

[0098] The magnesium silicon nitride powder prepared in this embodiment has severe agglomeration, with a particle size distribution of 0.5μm-10μm, a yield of 85.3%, and an oxygen content of 0.86wt.%.

[0099] Table 1 Performance characterization data of the examples and comparative examples

[0100] Note: In Table 1, “\” indicates that the relevant data could not be obtained because the product did not meet the test requirements.

[0101] The embodiments herein do not exhaustively cover the points not covered by the technical scope claimed in this application, and new technical solutions formed by equivalent substitutions of one or more technical features in the technical solutions of the embodiments are also within the scope of protection claimed in this application. At the same time, in all the listed or unlisted embodiments of the solution in this application, each parameter in the same embodiment merely represents an instance of its technical solution (i.e., a feasible solution), and there is no strict matching or limiting relationship between the parameters. The parameters can be substituted for each other without violating axioms and the claims of this application, unless otherwise stated.

[0102] The technical means disclosed in this application are not limited to those described above, but also include technical solutions composed of any combination of the above technical features. The above descriptions are specific embodiments of this application. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this application, and these improvements and modifications are also considered within the scope of protection of this application.

[0103] The specific embodiments described herein are merely illustrative examples of the technical solutions of this application. Those skilled in the art to which this application pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, but without departing from the spirit of this application or exceeding the scope defined by the appended claims.

Claims

1. A method for preparing magnesium silicon nitride powder, characterized in that, include: Silicon nitride powder is embedded in magnesium powder to form magnesium-based composite powder with a micro-nano composite structure on the surface. The magnesium-based composite powder is mixed with a dispersant to obtain a reaction precursor; The reaction precursor undergoes a self-propagating synthesis reaction to obtain silicon magnesium nitride composite powder; the silicon magnesium nitride composite powder is then subjected to acid washing and calcination treatments to obtain the silicon magnesium nitride powder.

2. The method according to claim 1, characterized in that: The pinning method includes plasma ball milling; The plasma ball milling atmosphere is a negative pressure inert atmosphere, the current is 60mA~80mA, the ball milling time is 1h~10h, the ball milling speed is 1200rpm~1400rpm, and the ball-to-material ratio is (5~30):

1.

3. The method according to claim 1, characterized in that: The dispersant includes at least one of ammonium carbonate, ammonium bicarbonate, and ammonium chloride; the dispersant is mixed by mechanical mixing, wherein the mechanical mixing speed is 30 rpm to 250 rpm.

4. The method according to claim 1, characterized in that: The mass ratio of the dispersant to the magnesium-based composite powder is (0.01~0.1):

1.

5. The method according to claim 1, characterized in that: The molar ratio of the magnesium powder to the silicon nitride powder is (1~4):

1.

6. The method according to claim 1, characterized in that: The self-propagating synthesis reaction is carried out in a nitrogen atmosphere or a nitrogen-hydrogen mixed atmosphere, and the reaction pressure of the self-propagating synthesis reaction is 0.5 MPa to 6 MPa.

7. The method according to claim 1, characterized in that: The calcination process is carried out in a nitrogen atmosphere at a temperature of 800℃ to 1000℃ for a duration of 1 hour to 4 hours.

8. The method according to claim 1, characterized in that: The magnesium powder has a particle size of 1μm to 50μm; the silicon nitride powder has a particle size of 30nm to 100nm. The micro-nano composite structure includes the magnesium powder and the silicon nitride powder, wherein the silicon nitride powder particles are anchored to the surface of the magnesium powder; and / or, the particle size of the magnesium-based composite powder is 800 nm to 30 μm.

9. A silicon magnesium nitride powder, characterized in that, The silicon magnesium nitride powder prepared by the method according to any one of claims 1-8 satisfies one or more of the following conditions: The particle size of the silicon magnesium nitride powder is 1μm~2μm; Based on the total molar number of the silicon nitride magnesium powder, the molar percentage of magnesium in the silicon nitride magnesium powder is 20%~50%, and the molar percentage of silicon nitride in the silicon nitride magnesium powder is 50%~80%. Based on the total mass of the silicon magnesium nitride powder, the mass percentage of oxygen in the silicon magnesium nitride powder is less than 0.15%. The yield of the silicon magnesium nitride is greater than or equal to 95%.

10. The application of magnesium silicon nitride powder prepared by the method of any one of claims 1-8, or magnesium silicon nitride powder as described in claim 9, in sintering aids, refractory material components, or reinforcing phases of metal matrix composites.

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