Silicon magnesium nitride powder, its preparation method and application

Abstract

This application relates to a silicon nitride magnesium powder, its preparation method, and its applications, belonging to the technical field of structural ceramic powder materials. The preparation method includes: embedding silicon nitride powder into magnesium powder to form a magnesium-based composite powder with a micro / nano composite structure on its surface; mixing the magnesium-based composite powder with a dispersant to obtain a reaction precursor; subjecting the reaction precursor to a self-propagating synthesis reaction to obtain the silicon nitride magnesium composite powder; and sequentially subjecting the silicon nitride magnesium composite powder to acid washing and calcination treatments to obtain the silicon nitride magnesium powder. The prepared silicon nitride magnesium has a yield of over 95%, an oxygen content of less than 0.15 wt.%, and a particle size controlled between 1 μm and 2 μm with uniform distribution; it is suitable for applications such as a sintering aid for high-performance ceramics, a component of refractory materials, and a reinforcing phase in metal matrix composites.

Description

Technical Field

[0001] This application relates to the field of structural ceramic powder materials technology, and in particular to a silicon magnesium nitride powder, its preparation method and application. Background Technology

[0002] Magnesium silicon nitride (MgSi) is an important nitride ceramic material. Due to its high thermal conductivity, excellent mechanical properties, stable chemical properties, and good high-temperature stability, it shows broad application prospects in high-performance ceramic substrates, microelectronic packaging, thermally conductive substrates, refractory materials, and metal matrix composite reinforcement phases. In recent years, with the development of electronic devices towards higher power and higher integration, higher requirements have been placed on the purity, particle size distribution, oxygen content, and crystallinity of magnesium silicon nitride powder.

[0003] In addition, existing technologies generally suffer from problems such as low reaction conversion rate, easy agglomeration of product particles, inaccurate control of oxygen content, and poor process repeatability, which restrict the application of silicon magnesium nitride in high-performance ceramics and electronic materials. Summary of the Invention

[0004] This application addresses the shortcomings of existing silicon-magnesium nitride powder synthesis technologies by providing a method for preparing high-quality silicon-magnesium nitride powder with high reaction efficiency, controllable product morphology and composition, high purity, and low oxygen content.

[0005] The objective of this application can be achieved through the following technical solutions.

[0006] The first aspect of this application provides a method for preparing magnesium silicon nitride powder, comprising the following steps:

[0007] Silicon nitride powder is embedded in magnesium powder to form magnesium-based composite powder with a micro-nano composite structure on the surface.

[0008] The magnesium-based composite powder is mixed with a dispersant to obtain a reaction precursor;

[0009] 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.

[0010] Preferably, 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.

[0011] The pinning step described in this application can simultaneously achieve interface pinning and activation effects. This application utilizes the synergistic effect of plasma discharge and high-energy mechanical ball milling to achieve continuous bombardment of the powder surface by high-energy electron beams under specific current (60mA-80mA), rotation speed (1200rpm-1400rpm), and ball-to-powder ratio ((5~30):1). This effectively removes the original oxide layer on the magnesium powder surface, exposing a highly active metal surface. At the same time, the intense mechanical collision pins nanoscale silicon nitride particles into the plastic matrix of micron-scale magnesium powder, forming a robust 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, achieving a composite interface and a highly active state. This allows subsequent self-propagating reactants to undergo atomic / ion exchange within a short range without long-range bulk diffusion, thereby significantly reducing the activation energy of the synthesis reaction, effectively suppressing magnesium volatilization, and thus achieving high conversion rate and rapid reaction.

[0012] More preferably, the dispersant includes at least one of ammonium carbonate, ammonium bicarbonate, and ammonium chloride; the dispersant is mixed by mechanical mixing or manual mixing; the mechanical mixing speed is 30 rpm to 250 rpm; and the mass ratio of the dispersant to the magnesium-based composite powder is (0.01 to 0.1):1.

[0013] 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 gases, which escape from the interior of the powder, thereby achieving in-situ pore formation. The resulting porous structure not only constructs temporary gas channels and physical spaces between reactant particles, promoting the full reaction of kilogram-scale reactants, but also effectively limits the excessive spreading and coalescence of magnesium melt during the reaction process, preventing the powder from densifying and sintering. In addition, this porous structure facilitates the deep penetration of nitrogen into the reaction interface, while the reducing atmosphere created during the decomposition process helps maintain a low oxygen partial pressure in the reaction region, thus ensuring the high purity of the final product.

[0014] The molar ratio of magnesium powder to silicon nitride powder is (1~4):1; and / or, the silicon nitride includes α-Si3N4.

[0015] 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 to 6 MPa; the reaction is started by an igniter, which includes at least one of titanium powder, carbon powder, and magnesium powder.

[0016] Preferably, the silicon nitride magnesium composite powder is subjected to multi-step acid washing to remove excess magnesium powder and its oxides; the calcination treatment is carried out in a nitrogen atmosphere at a temperature of 800℃~1000℃ for a time of 1h~4h.

[0017] The multi-step pickling process described in this application can effectively dissolve byproducts generated during the reaction, such as MgO and Mg2Si; the nitrogen atmosphere calcination process can remove residual trace amounts of adsorbed water and volatile impurities from the powder and reduce the oxygen content; at the same time, it can effectively eliminate the internal stress generated by the rapid cooling of the powder due to the self-propagating reaction and improve the crystallinity of the product to achieve chemical stability and physical properties.

[0018] The magnesium powder has a particle size of 1μm to 50μm; the silicon nitride powder has a particle size of 30nm to 100nm.

[0019] The micro / nano composite structure comprises magnesium powder and silicon nitride powder, with silicon nitride particles anchored to the surface of the magnesium powder. This allows for the formation of a heterogeneous composite interface with high interfacial bonding strength. In this application, the particle size of the magnesium-based composite powder is 800 nm to 30 μm.

[0020] In a second aspect of this application, a magnesium silicon nitride powder prepared by the method of the first aspect is provided; the magnesium silicon nitride powder satisfies one or more of the following conditions:

[0021] The particle size of the silicon magnesium nitride powder is 1μm~2μm;

[0022] 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%.

[0023] 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%.

[0024] The yield of the silicon magnesium nitride is greater than or equal to 95%.

[0025] In a third aspect, this application provides the application of the aforementioned magnesium silicon nitride powder in sintering aids, refractory material components, or reinforcing phases of metal matrix composites.

[0026] The beneficial effects of the high-yield method for preparing magnesium silicon nitride powder in this application include:

[0027] (1) The micro-nano composite structure constructed by plasma ball milling significantly reduces the activation energy of the self-propagating reaction, improves the reaction conversion rate, and stabilizes the yield at over 95%.

[0028] (2) The decomposition of dispersant can not only be used to create pores and make the reaction complete; it can also create a local reducing atmosphere, which, combined with subsequent acid washing and nitrogen calcination, can effectively remove impurities such as MgO and Mg2S and adsorbed water, so that the oxygen content of the final product is strictly controlled below 0.15wt.%;

[0029] (3) The gas channels generated by the decomposition of the dispersant prevent the excessive spreading of molten magnesium and the sintering and agglomeration of particles. The resulting silicon nitride magnesium powder has a narrow particle size distribution (1μm-2μm) and excellent dispersibility. Attached Figure Description

[0030] Figure 1 This is a microscopic morphology diagram of the magnesium silicon nitride powder prepared in Example 1.

[0031] Figure 2 This is a microscopic morphology diagram of the magnesium silicon nitride powder prepared in Example 2.

[0032] Figure 3 This is a microscopic morphology diagram of the magnesium silicon nitride powder prepared in Example 3.

[0033] Figure 4 This is a microscopic morphology diagram of the magnesium silicon nitride powder prepared in Example 4.

[0034] Figure 5 The image shows the XRD pattern of magnesium silicon nitride prepared in Example 1.

[0035] Figure 6 The image shows the XRD pattern of magnesium silicon nitride prepared in Example 2.

[0036] Figure 7 The image shows the XRD pattern of magnesium silicon nitride prepared in Example 3.

[0037] Figure 8 The image shows the XRD pattern of magnesium silicon nitride prepared in Example 4. Detailed Implementation

[0038] The following detailed description, with appropriate reference to the accompanying drawings, discloses the silicon magnesium nitride powder, its preparation method, and embodiments of its application. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of essentially the same structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0039] 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.

[0040] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0041] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0042] 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).

[0043] 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.

[0044] 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:

[0045] Silicon nitride powder is embedded in magnesium powder to form magnesium-based composite powder with a micro-nano composite structure on the surface.

[0046] The magnesium-based composite powder is mixed with a dispersant to obtain a reaction precursor;

[0047] 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.

[0048] 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.

[0049] 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.

[0050] The mass ratio of the dispersant to the magnesium-based composite powder is (0.01~0.1):1.

[0051] The molar ratio of magnesium powder to silicon nitride powder is (1~4):1; and / or, the silicon nitride is selected from α-Si3N4.

[0052] 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.

[0053] 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.

[0054] The magnesium powder has a particle size of 1μm to 50μm; the silicon nitride powder has a particle size of 30nm to 100nm.

[0055] The particle size of the magnesium-based composite powder is 800 nm to 30 μm.

[0056] Example 1:

[0057] 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.

[0058] S1. The silicon nitride powder is pinned into the magnesium powder substrate to form a magnesium-based composite powder.

[0059] 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;

[0060] 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.

[0061] 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.

[0062] S2. The magnesium-based composite powder is uniformly mixed with the dispersant to obtain the reaction precursor powder.

[0063] 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.

[0064] 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.

[0065] S3. The reaction precursor undergoes a self-propagating synthesis reaction to obtain silicon magnesium nitride composite powder.

[0066] The precursor powder was loosely packed in a high-purity graphite crucible, with a loose packing density of 0.85 g / cm³. 3 .

[0067] 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.

[0068] 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.

[0069] S4. The silicon nitride magnesium composite powder is subjected to acid washing and calcination treatment in sequence to obtain silicon nitride magnesium powder.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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).

[0074] 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.

[0075] Example 2:

[0076] The reaction materials in this embodiment are the same as in Example 1, except that the dispersant used is ammonium carbonate.

[0077] 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.

[0078] S2. In the same manner as in Example 1, 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.

[0079] S3. The reaction precursor undergoes a self-propagating synthesis reaction to obtain silicon magnesium nitride composite powder.

[0080] The reaction precursor was loosely packed in a high-purity alumina crucible, with a loose packing density of 0.90 g / cm³. 3 .

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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).

[0085] 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.

[0086] Example 3:

[0087] The silicon nitride magnesium raw material composition in this embodiment is the same as in Example 1;

[0088] 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.

[0089] S2. In the same manner as in Example 1, magnesium-based composite powder and dispersant are uniformly mixed to obtain a reaction precursor.

[0090] S3. The precursor powder undergoes a self-propagating synthesis reaction to obtain silicon magnesium nitride composite powder.

[0091] The reaction precursor was loosely packed in a high-purity graphite crucible with a loose packing density of 0.70 g / cm³.

[0092] 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.

[0093] 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.

[0094] S4. The silicon nitride magnesium composite powder is subjected to multi-step acid washing and calcination to obtain silicon nitride magnesium powder.

[0095] 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.

[0096] After pickling, wash with deionized water until neutral, and dry in a vacuum drying oven at 100°C for 12 hours.

[0097] 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.

[0098] 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).

[0099] 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.

[0100] Example 4:

[0101] The reaction raw materials in this embodiment are the same as in Example 1, except that the dispersant used is ammonium bicarbonate.

[0102] S1. The silicon nitride powder is pinned into the magnesium powder substrate to form a magnesium-based composite powder.

[0103] 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;

[0104] 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.

[0105] S2. Mix the magnesium-based composite powder with the dispersant evenly to obtain the reaction precursor powder.

[0106] 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.

[0107] S3. The precursor powder undergoes a self-propagating synthesis reaction to obtain silicon magnesium nitride composite powder.

[0108] The precursor powder was loosely packed in a high-purity graphite crucible with a loose packing density of 0.75 g / cm³.

[0109] 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.

[0110] 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.

[0111] S4. The silicon nitride magnesium composite powder is subjected to acid washing and calcination treatment to obtain silicon nitride magnesium powder.

[0112] 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.

[0113] 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).

[0114] 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.

[0115] Comparative Example 1

[0116] 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.

[0117] 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.

[0118] Comparative Example 2

[0119] 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.

[0120] 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.

[0121] Example 5

[0122] 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.

[0123] 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.

[0124] Example 6

[0125] 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.

[0126] 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.%.

[0127] Table 1 Performance characterization data of the examples and comparative examples

[0128]

[0129] Note: In Table 1, “\” indicates that the relevant data could not be obtained because the product did not meet the test requirements.

[0130] 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.

[0131] 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.

[0132] 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 a magnesium-based composite powder with a micro-nano composite structure on the surface; the particle size of the magnesium powder is 1μm~50μm; the particle size of the silicon nitride powder is 30nm~100nm; the micro-nano composite structure includes the magnesium powder and the silicon nitride powder, and the silicon nitride powder particles are embedded in the surface of the magnesium powder. The magnesium-based composite powder is mixed with a dispersant to obtain a reaction precursor; the dispersant includes at least one of ammonium carbonate, ammonium bicarbonate, and ammonium chloride. 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. 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.

2. The method according to claim 1, characterized in that: The dispersant is mixed by mechanical mixing, wherein the mechanical mixing speed is 30 rpm to 250 rpm.

3. 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.

4. 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.

5. 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.

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

7. The method according to claim 1, characterized in that: The particle size of the magnesium-based composite powder is 800 nm to 30 μm.

8. A silicon magnesium nitride powder, characterized in that, The silicon magnesium nitride powder prepared by the method according to any one of claims 1-7 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%.

9. The application of magnesium silicon nitride powder prepared by the method of any one of claims 1-7, or magnesium silicon nitride powder as described in claim 8, in sintering aids, refractory material components, or reinforcing phases of metal matrix composites.

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