A method for producing spherical aluminum nitride powder for a thermally conductive filler

Abstract

The present application relates to the field of spherical aluminum nitride powder, and particularly relates to a preparation method of spherical aluminum nitride powder for heat-conducting filler, which comprises the following steps: taking spherical aluminum oxide as a precursor, mixing with a sintering aid, and then performing carbon thermal reduction reaction under a nitrogen atmosphere in a preset environment to generate spherical aluminum nitride powder. The preliminary product is subjected to heat-conducting performance test and preliminary determination. For the preliminary product that does not meet the standard, further spherical characteristic value analysis and nitrogen flow adjustment are performed to optimize sphericity, or agglomeration index analysis and heating or cooling rate adjustment are performed to inhibit agglomeration. For the preliminary product that meets the standard, carbon removal treatment is performed, and the removal temperature is adjusted by monitoring the specific surface area of the product. The present application effectively solves the problems of low sphericity, easy agglomeration and poor heat-conducting performance in the traditional method, and can stably prepare aluminum nitride powder with high sphericity, low agglomeration and strong heat-conducting performance.

Description

Technical Field

[0001] This invention relates to the field of spherical aluminum nitride powder technology, and more particularly to a method for preparing spherical aluminum nitride powder for use as a thermally conductive filler. Background Technology

[0002] In the field of thermally conductive fillers, spherical aluminum nitride powder is widely used in high-performance composite materials such as electronic packaging and heat dissipation substrates due to its high thermal conductivity, low dielectric constant, and good thermal matching. However, the core problem of low sphericity is that spherical aluminum nitride powder used in existing thermally conductive fillers is generally low. Specifically, this manifests as irregular powder particle morphology, high surface roughness, and a significant tendency to agglomerate, leading to reduced filling density and obstructed heat conduction paths, ultimately limiting the improvement of the thermal conductivity and reliability optimization of composite materials.

[0003] Traditional preparation methods, such as direct nitriding and carbothermic reduction, can synthesize aluminum nitride powder, but they have significant limitations in controlling sphericity.

[0004] Firstly, when irregular alumina or aluminum nitride is used as raw material, the original angular structure of the particles is easily retained after high-temperature nitriding reaction, making it difficult to form products with high sphericity. Even if spherical alumina is used as a precursor, insufficient surface tension or local overheating during high-temperature sintering can still easily lead to particle deformation and melting adhesion.

[0005] Secondly, even slight deviations in parameters such as nitriding reaction temperature, nitrogen flow rate, and holding time can easily lead to surface roughening, increased internal porosity, or abnormal grain growth in the particles, directly affecting the sphericity of the final powder. For example, insufficient nitrogen flow rate may result in incomplete alumina reduction and residual impurity phases; excessively high temperatures or prolonged holding times may cause particle melting and agglomeration, destroying the spherical structure. Thirdly, current technologies for quantitatively assessing sphericity largely rely on manual visual inspection or simple particle size distribution testing, lacking a dynamic control mechanism based on the correlation between thermal conductivity and morphology. When the initial thermal conductivity of the powder does not meet the standard, traditional methods struggle to accurately pinpoint the root cause, leading to significant blind adjustments in the process and difficulty in improving yield. Finally, improper control of the oxidizing atmosphere during the decarbonization stage can easily lead to powder surface oxidation, a surge in specific surface area, or localized sintering, further deteriorating sphericity and thermal conductivity. Current technologies lack a decarbonization parameter optimization strategy based on dynamic feedback of specific surface area, making it difficult to achieve a balanced control between carbon residue and sphericity. Summary of the Invention

[0006] Therefore, the present invention provides a method for preparing spherical aluminum nitride powder for thermally conductive fillers, in order to overcome the problem of low sphericity of spherical aluminum nitride powder for thermally conductive fillers in the prior art.

[0007] To achieve the above objectives, the present invention provides a method for preparing spherical aluminum nitride powder for thermally conductive fillers, comprising:

[0008] Step S1: Obtain spherical alumina and sintering aid within a preset particle size range;

[0009] Step S2: Mix the spherical alumina with the sintering aid to obtain a mixture.

[0010] Step S3: The mixture is embedded in carbon powder and placed into a crucible;

[0011] Step S4: Place the sagger containing the mixture and carbon powder into a high-temperature calcining furnace for nitrogen atmosphere calcination treatment. The calcination treatment parameters include a first preset flow rate of nitrogen, a first preset temperature, and a first preset duration.

[0012] Step S5: Remove the sagger from the high-temperature calcining furnace and cool it to room temperature under a nitrogen atmosphere with a first preset flow rate to obtain spherical aluminum nitride powder initial product;

[0013] Step S6: Perform thermal conductivity test on the spherical aluminum nitride powder sample to obtain the thermal conductivity coefficient of the spherical aluminum nitride powder sample, and preliminarily determine whether the preparation of the spherical aluminum nitride powder sample meets the preset standard based on the thermal conductivity coefficient.

[0014] Step S7: In response to the preliminary determination that the preparation of the spherical aluminum nitride powder does not meet the preset standard, the preparation of the spherical aluminum nitride powder does not meet the preset standard based on the spherical characteristic value of the spherical aluminum nitride powder, or the reason why the preparation of the spherical aluminum nitride powder does not meet the preset standard is determined based on the agglomeration index.

[0015] Step S8: In response to the determination that the preparation of the spherical aluminum nitride powder initial product meets the preset standard, the spherical aluminum nitride powder initial product that meets the preset standard is placed in an oxidizing atmosphere for decarbonization treatment to obtain the spherical aluminum nitride powder finished product; the decarbonization treatment parameters include a second preset flow rate, a second preset temperature, and a second preset duration.

[0016] Step S9: Obtain the specific surface area of ​​the spherical aluminum nitride powder product, and determine whether the decarbonization treatment of the spherical aluminum nitride powder product meets the preset standard based on the specific surface area.

[0017] Furthermore, in response to the thermal conductivity being less than the second preset thermal conductivity, it is preliminarily determined that the preparation of the spherical aluminum nitride powder prototype does not meet the preset standard;

[0018] In response to the thermal conductivity being greater than or equal to a second preset thermal conductivity, it is determined that the preparation of the spherical aluminum nitride powder precursor meets the preset standard.

[0019] Furthermore, in response to the fact that the thermal conductivity is less than the first preset thermal conductivity, the reason why the preparation of the spherical aluminum nitride powder initial product does not meet the preset standard is determined according to the agglomeration index;

[0020] In response to the thermal conductivity being greater than or equal to a first preset thermal conductivity and less than a second preset thermal conductivity, the preparation of the initial spherical aluminum nitride powder is verified according to the spherical characteristic value of the spherical aluminum nitride powder to determine whether it meets the preset standard.

[0021] Furthermore, in response to the spherical feature value being less than a preset spherical feature value threshold, it is verified whether the preparation of the spherical aluminum nitride powder initial product meets the preset standard;

[0022] In response to the spherical feature value being greater than or equal to a preset spherical feature value threshold, the preparation of the spherical aluminum nitride powder precursor is verified to be inconsistent with the preset standard, and the nitrogen flow rate of the first preset flow rate is reduced according to the difference between the spherical feature value and the preset spherical feature value threshold.

[0023] Furthermore, the reduction in the nitrogen flow rate of the first preset flow rate is positively correlated with the difference between the spherical feature value and the preset spherical feature value threshold.

[0024] Furthermore, the spherical characteristic value is the ratio of the standard deviation of the diameter of the spherical aluminum nitride powder in several directions to the average diameter.

[0025] Furthermore, the reasons why the preparation of the initial spherical aluminum nitride powder did not meet the preset standards were determined based on the agglomeration index, wherein...

[0026] If the agglomeration index is less than the preset agglomeration index threshold, it is determined that the reason why the preparation of the spherical aluminum nitride powder does not meet the preset standard is that the heating rate of the high-temperature calcining furnace is not up to standard, and the heating rate of the high-temperature calcining furnace is increased according to the difference between the preset agglomeration index threshold and the agglomeration index.

[0027] If the agglomeration index is greater than or equal to the preset agglomeration index threshold, the reason why the preparation of the spherical aluminum nitride powder does not meet the preset standard is that the sagger cooling rate is not up to standard, and the sagger cooling rate is reduced according to the difference between the agglomeration index and the preset agglomeration index threshold.

[0028] The agglomeration index is the ratio of the number of agglomerates to the total number of particles in the initial spherical aluminum nitride powder.

[0029] Furthermore, the heating rate of the high-temperature calcining furnace is positively correlated with the difference between the preset agglomeration index threshold and the agglomeration index.

[0030] Furthermore, the decrease in the sagger cooling rate is positively correlated with the difference between the agglomeration index and the preset agglomeration index threshold.

[0031] Furthermore, based on the specific surface area, it is determined whether the decarbonization treatment of the spherical aluminum nitride powder product meets the preset standard, wherein,

[0032] If the specific surface area is less than the preset specific surface area threshold, then the decarbonization treatment of the spherical aluminum nitride powder product is determined to meet the preset standard.

[0033] If the specific surface area is greater than or equal to a preset specific surface area threshold, it is determined that the decarbonization treatment of the spherical aluminum nitride powder product does not meet the preset standard, and the second preset temperature is reduced according to the difference between the specific surface area and the preset specific surface area threshold.

[0034] Furthermore, the decrease in the second preset temperature is positively correlated with the difference between the specific surface area and the preset specific surface area threshold.

[0035] Compared with existing technologies, the advantages of this invention are as follows: This invention uses spherical alumina as a precursor and directly generates spherical aluminum nitride through a carbothermic reduction reaction, inheriting the spherical morphology of the raw material. This method avoids the problems of low sphericity and rough surface caused by insufficient melting and improper cooling in traditional physical methods from the reaction mechanism perspective. Therefore, it can stably prepare aluminum nitride powder with high sphericity, laying a structural foundation for the high thermal conductivity of the final product.

[0036] Furthermore, this invention breaks through the passive mode of traditional preparation methods by introducing a multi-level feedback judgment system based on thermal conductivity, spherical characteristic value, agglomeration index, and specific surface area. This system can not only accurately diagnose whether the product meets the standards, but also further pinpoint specific problems in the production process and realize automatic and precise reverse adjustment of process parameters, thereby improving the intelligence of the production process and the consistency of product quality.

[0037] Furthermore, by designing the reaction to involve "embedding carbon powder" and conducting it at a specific nitrogen flow rate, a uniform and controllable local environment is created for the carbothermic reduction reaction. The mechanism in step S7 that adjusts the nitrogen flow rate based on the spherical characteristic value feedback effectively prevents particle adhesion, sintering, or morphological collapse caused by uneven reaction atmosphere or excessively vigorous reaction, ensuring that the morphology of the initial spherical alumina can be inherited by the final product.

[0038] Furthermore, traditional decarbonization processes are prone to surface oxidation of aluminum nitride powder due to temperature runaway, forming an aluminum oxide layer that severely impairs thermal conductivity. This invention addresses this by controlling the decarbonization temperature in reverse based on the specific surface area of ​​the powder after decarbonization. This allows for finding the optimal process window that thoroughly removes residual carbon while maximally suppressing the oxidation of the aluminum nitride itself, thus ensuring the high purity and high thermal conductivity of the final product.

[0039] Furthermore, this invention creatively uses the "agglomeration index" as a key diagnostic indicator, and can clearly distinguish whether agglomeration is caused by "insufficient heating rate" or "insufficient cooling rate," and adjust the relevant parameters accordingly. This fundamentally solves the problems of poor dispersibility and poor flowability caused by hard agglomeration of powder, allowing it to be more uniformly distributed in the matrix when used as a thermally conductive filler, forming a highly efficient thermally conductive network.

[0040] Furthermore, the process of this invention has a high degree of integration, and through its built-in intelligent feedback and adjustment system, it can quickly stabilize the process, reducing waste and downtime caused by trial and error and batch non-conformities. At the same time, the carbothermic reduction route using spherical alumina as raw material has a greater advantage in terms of cost for large-scale production compared to the plasma spheroidization method, which is highly dependent on high-end equipment and has high energy consumption. Attached Figure Description

[0041] Figure 1 This is a flowchart illustrating the preparation method of spherical aluminum nitride powder for thermally conductive fillers according to an embodiment of the present invention.

[0042] Figure 2 This invention provides a flowchart for the preliminary determination of whether the preparation of the spherical aluminum nitride powder initial product conforms to a preset standard based on the thermal conductivity.

[0043] Figure 3 The present invention provides a flowchart for verifying whether the preparation of the initial spherical aluminum nitride powder conforms to a preset standard based on the spherical characteristic value of the spherical aluminum nitride powder in this embodiment of the invention.

[0044] Figure 4 This is a flowchart illustrating the reasons why the preparation of the initial spherical aluminum nitride powder does not meet the preset standard based on the agglomeration index, according to an embodiment of the present invention.

[0045] Figure 5 This is a flowchart illustrating the process of determining whether the decarbonization treatment of the spherical aluminum nitride powder product meets the preset standard based on the specific surface area, as described in this embodiment of the invention. Detailed Implementation

[0046] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0047] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0048] Please see Figure 1-5 The following are flowcharts illustrating the preparation methods of spherical aluminum nitride powder for thermally conductive fillers according to embodiments of the present invention: a flowchart illustrating the preliminary determination of whether the preparation of the initial spherical aluminum nitride powder conforms to a preset standard based on thermal conductivity; a flowchart illustrating the verification of whether the preparation of the initial spherical aluminum nitride powder conforms to a preset standard based on the spherical characteristic value of the spherical aluminum nitride powder; a flowchart illustrating the determination of the reasons why the preparation of the initial spherical aluminum nitride powder does not conform to the preset standard based on the agglomeration index; and a flowchart illustrating the determination of whether the decarbonization treatment of the finished spherical aluminum nitride powder conforms to a preset standard based on the specific surface area.

[0049] An embodiment of the present invention provides a method for preparing spherical aluminum nitride powder for use as a thermally conductive filler, comprising:

[0050] Step S1: Obtain spherical alumina and sintering aid within a preset particle size range;

[0051] Step S2: Mix the spherical alumina with the sintering aid to obtain a mixture.

[0052] Step S3: The mixture is embedded in carbon powder and placed into a crucible;

[0053] Step S4: Place the sagger containing the mixture and carbon powder into a high-temperature calcining furnace for nitrogen atmosphere calcination treatment. The calcination treatment parameters include a first preset flow rate of nitrogen, a first preset temperature, and a first preset duration.

[0054] Step S5: Remove the sagger from the high-temperature calcining furnace and cool it to room temperature under a nitrogen atmosphere with a first preset flow rate to obtain spherical aluminum nitride powder initial product;

[0055] Step S6: Perform thermal conductivity test on the spherical aluminum nitride powder sample to obtain the thermal conductivity coefficient of the spherical aluminum nitride powder sample, and preliminarily determine whether the preparation of the spherical aluminum nitride powder sample meets the preset standard based on the thermal conductivity coefficient.

[0056] Step S7: In response to the preliminary determination that the preparation of the spherical aluminum nitride powder does not meet the preset standard, the preparation of the spherical aluminum nitride powder does not meet the preset standard based on the spherical characteristic value of the spherical aluminum nitride powder, or the reason why the preparation of the spherical aluminum nitride powder does not meet the preset standard is determined based on the agglomeration index.

[0057] Step S8: In response to the determination that the preparation of the spherical aluminum nitride powder initial product meets the preset standard, the spherical aluminum nitride powder initial product that meets the preset standard is placed in an oxidizing atmosphere for decarbonization treatment to obtain the spherical aluminum nitride powder finished product; the decarbonization treatment parameters include a second preset flow rate, a second preset temperature, and a second preset duration.

[0058] Step S9: Obtain the specific surface area of ​​the spherical aluminum nitride powder product, and determine whether the decarbonization treatment of the spherical aluminum nitride powder product meets the preset standard based on the specific surface area.

[0059] Specifically, the preset particle size range is set to 1μm-100μm, preferably 60μm; the first preset flow rate is set to 5L / min-15L / min, preferably 10L / min; the first preset temperature is set to 1600℃-1800℃, preferably 1700℃; the first preset duration is set to 4h-10h, preferably 7h; the second preset flow rate is set to 10L / min-20L / min, preferably 15L / min; the second preset temperature is set to 500℃-700℃, preferably 600℃; and the second preset duration is set to 2h-5h, preferably 3h. It should be noted that the data in this embodiment are all results obtained through preliminary experimental verification before the method of this invention is implemented. Each preset value can be adjusted according to specific usage conditions, as long as the method of this invention can clearly define different specific situations in the single-item judgment process through the obtained values.

[0060] Specifically, in practice, the first step is to strictly select spherical alumina and sintering aids according to the preset particle size range to ensure that the quality and specifications of the raw materials meet the requirements. The selected spherical alumina and sintering aids are then placed in a specialized mixing device, where thorough stirring and mixing ensure uniform distribution, resulting in a stable mixture. Next, the mixture is carefully embedded in carbon powder, ensuring complete encapsulation. The crucible containing the mixture and carbon powder is then steadily placed into a high-temperature calcining furnace. The nitrogen supply system is activated, and the nitrogen flow rate is precisely adjusted to the first preset flow rate. Simultaneously, the temperature of the high-temperature calcining furnace is set to the first preset temperature, and a timer is started, allowing the mixture to react under the set conditions for the first preset time. After the reaction is complete, the crucible is quickly removed from the high-temperature calcining furnace. Throughout the cooling process, a nitrogen atmosphere at the preset flow rate is maintained to prevent the initial spherical aluminum nitride powder from reacting with oxygen in the air, until it cools to room temperature.

[0061] Specifically, a TPS 2500S probe is selected and sandwiched between two samples. A constant current is applied to heat the probe, and the thermal conductivity is calculated by measuring the change in probe resistance over time. A laser particle size analyzer is used to calculate the spherical characteristic value, and relevant data is obtained based on the analysis and processing of the scattered light signal from the sample particles. An agglomeration index analyzer is used to calculate the agglomeration index, which quantifies the agglomeration of sample particles using a specific method. A specific surface area analyzer is used to calculate the specific surface area, obtaining the value by measuring parameters such as the amount of gas adsorbed in the sample. The specific equipment used is not limited, as long as it can output corresponding data results based on the parameters of the spherical aluminum nitride powder.

[0062] Specifically, in response to the thermal conductivity being less than the second preset thermal conductivity, it is preliminarily determined that the preparation of the spherical aluminum nitride powder prototype does not meet the preset standard;

[0063] In response to the thermal conductivity being greater than or equal to a second preset thermal conductivity, it is determined that the preparation of the spherical aluminum nitride powder precursor meets the preset standard.

[0064] Specifically, in response to the fact that the thermal conductivity is less than the first preset thermal conductivity, the reason why the preparation of the spherical aluminum nitride powder initial product does not meet the preset standard is determined according to the agglomeration index;

[0065] In response to the thermal conductivity being greater than or equal to a first preset thermal conductivity and less than a second preset thermal conductivity, the preparation of the initial spherical aluminum nitride powder is verified according to the spherical characteristic value of the spherical aluminum nitride powder to determine whether it meets the preset standard.

[0066] Specifically, the first preset thermal conductivity is set to 200 W / (m·k), and the second preset thermal conductivity is set to 320 W / (m·k). By judging according to different ranges of thermal conductivity, this method provides a clear and easy-to-operate standard for quality control in the production process, which helps to improve the stability and consistency of the product and ensure that the final spherical aluminum nitride powder is stable and consistent.

[0067] Specifically, thermal conductivity is chosen as the evaluation standard because it is a crucial indicator of a material's ability to conduct heat. For thermally conductive fillers, their thermal conductivity directly determines their effectiveness in practical applications. As a thermally conductive filler, higher thermal conductivity of spherical aluminum nitride powder means it can more efficiently conduct heat from the heat source to the heat dissipation part, thereby improving the overall system's heat dissipation efficiency. In fields with extremely high heat dissipation requirements, such as electronic devices and power electronic components, fillers with high thermal conductivity can ensure that equipment maintains a stable temperature under long-term high-load operation, avoiding performance degradation, shortened lifespan, or even damage due to overheating. Using thermal conductivity as the evaluation standard directly and accurately reflects the thermal conductivity of spherical aluminum nitride powder in practical applications, providing a key basis for product quality control and performance optimization. By setting a reasonable thermal conductivity threshold, it is possible to clearly distinguish between high-quality products that meet the requirements and substandard products that do not, allowing for timely adjustments and improvements during the production process to ensure that the final product meets the stringent thermal conductivity requirements of different application scenarios.

[0068] Specifically, in response to the spherical feature value being less than a preset spherical feature value threshold, the preparation of the spherical aluminum nitride powder initial product is verified to meet a preset standard;

[0069] In response to the spherical feature value being greater than or equal to a preset spherical feature value threshold, the preparation of the spherical aluminum nitride powder precursor is verified to be inconsistent with the preset standard, and the nitrogen flow rate of the first preset flow rate is reduced according to the difference between the spherical feature value and the preset spherical feature value threshold.

[0070] Specifically, the preset spherical characteristic value threshold is set to 0.15, which is determined based on a comprehensive analysis of extensive experimental data and actual production requirements. In actual operation, close attention should be paid to changes in the spherical characteristic value, and the nitrogen flow rate should be precisely adjusted according to the difference to ensure that the produced spherical aluminum nitride powder has high-quality sphericity.

[0071] Specifically, the reduction in nitrogen flow rate at the first preset flow rate is positively correlated with the difference between the spherical characteristic value and the preset spherical characteristic value threshold. It is understood that the positive correlation can be linear or nonlinear, and is not specifically limited. The slope of the linear positive correlation is also not specifically limited and can be set according to the actual preparation conditions, as long as the larger the difference between the spherical characteristic value and the preset spherical characteristic value threshold, the greater the reduction in nitrogen flow rate at the first preset flow rate. For example, if the reduction in nitrogen flow rate at the first preset flow rate is set to ΔM, and the difference between the spherical characteristic value and the preset spherical characteristic value threshold is set to Δμ, then ΔM = γ × (Δμ + μ0), where γ is the flow rate adjustment coefficient, set to 1.06, and μ0 is a constant.

[0072] Specifically, the sphericity characteristic value is the ratio of the standard deviation of the diameter of the initial spherical aluminum nitride powder in several directions to the average diameter. It is understood that using this sphericity characteristic value as an evaluation standard can accurately quantify the sphericity of the powder particles, avoiding the subjectivity and inaccuracy of traditional visual judgment or simple size measurement. By calculating the ratio of the standard deviation of the diameter to the average diameter in multiple directions, the morphological characteristics of the particles in three-dimensional space can be comprehensively reflected, ensuring that the evaluation of sphericity is scientific and reliable. Furthermore, this indicator is closely related to thermal conductivity; the higher the sphericity, the closer the contact between particles, and the more efficient the heat conduction path, thereby significantly improving the overall thermal conductivity of the material.

[0073] Specifically, the reasons why the preparation of the initial spherical aluminum nitride powder did not meet the preset standard were determined based on the agglomeration index.

[0074] If the agglomeration index is less than the preset agglomeration index threshold, it is determined that the reason why the preparation of the spherical aluminum nitride powder does not meet the preset standard is that the heating rate of the high-temperature calcining furnace is not up to standard, and the heating rate of the high-temperature calcining furnace is increased according to the difference between the preset agglomeration index threshold and the agglomeration index.

[0075] If the agglomeration index is greater than or equal to the preset agglomeration index threshold, the reason why the preparation of the spherical aluminum nitride powder does not meet the preset standard is that the sagger cooling rate is not up to standard, and the sagger cooling rate is reduced according to the difference between the agglomeration index and the preset agglomeration index threshold.

[0076] The agglomeration index is the ratio of the number of agglomerates to the total number of particles in the initial spherical aluminum nitride powder.

[0077] Specifically, the preset agglomeration index threshold is set at 5%. This threshold, derived through experimental verification, effectively distinguishes agglomeration problems caused by substandard heating and cooling rates. In actual production, if the agglomeration index is found to exceed the preset threshold, the corresponding process parameters should be adjusted immediately based on the difference to ensure the powder's dispersibility and flowability.

[0078] Specifically, using the agglomeration index as an evaluation criterion can directly reflect the degree of powder particle agglomeration, which is closely related to the powder's dispersibility, flowability, and performance as a thermally conductive filler. By quantifying the ratio of the number of agglomerates to the total number of particles, the agglomeration status of the powder can be objectively and accurately assessed, providing a scientific basis for adjusting process parameters.

[0079] Specifically, the heating rate of the high-temperature calcining furnace is positively correlated with the difference between the preset agglomeration index threshold and the agglomeration index.

[0080] Specifically, the reduction in the sagger cooling rate is directly related to the difference between the agglomeration index and the preset agglomeration index threshold. It is understood that the adjustment parameter for reducing the sagger cooling rate can refer to the method for reducing the nitrogen flow rate of the first preset flow rate, which will not be elaborated here.

[0081] Specifically, in practice, the heating rate of the high-temperature calcining furnace needs to be precisely controlled. When the agglomeration index is detected to exceed the preset threshold, the heating rate should be increased accordingly based on the difference to improve the powder agglomeration. Similarly, the adjustment of the crucible cooling rate also needs to be cautious. The cooling rate should be reasonably reduced based on the difference between the agglomeration index and the preset threshold to ensure that the quality of the initial spherical aluminum nitride powder meets the preset standards. Through such dynamic adjustments, the preparation process can be effectively optimized, and the performance of the powder can be improved.

[0082] Specifically, the decarbonization treatment of the spherical aluminum nitride powder product is judged based on the specific surface area to determine whether it meets a preset standard.

[0083] If the specific surface area is less than the preset specific surface area threshold, then the decarbonization treatment of the spherical aluminum nitride powder product is determined to meet the preset standard.

[0084] If the specific surface area is greater than or equal to a preset specific surface area threshold, it is determined that the decarbonization treatment of the spherical aluminum nitride powder product does not meet the preset standard, and the second preset temperature is reduced according to the difference between the specific surface area and the preset specific surface area threshold.

[0085] Specifically, the preset specific surface area threshold is set to 12 m² / g. This threshold is determined based on a comprehensive evaluation of the decarbonization effect and powder performance. In actual production, specific surface area is a key indicator for judging whether the decarbonization treatment meets the standards, directly reflecting the powder surface adsorption capacity and reactivity. When the specific surface area exceeds the preset threshold, it indicates that the decarbonization treatment may be incomplete, and residual carbon elements affect the powder surface structure. In this case, the second preset temperature should be appropriately reduced according to the difference to optimize the oxidation reaction conditions and ensure that the carbon elements are fully removed.

[0086] Specifically, specific surface area is chosen as the evaluation criterion because it comprehensively reflects the surface characteristics and purity of the powder. For thermally conductive fillers, an excessively high specific surface area may indicate residual carbon elements or incomplete oxidation. These impurities can form a thermally resistive layer, reducing the thermal conductivity of the powder. By setting a reasonable specific surface area threshold, the decarbonization process can be ensured to achieve the desired effect, resulting in a clean surface and moderate activity of the spherical aluminum nitride powder, thus maximizing its thermal conductivity in practical applications.

[0087] Specifically, in practice, the specific surface area of ​​the finished spherical aluminum nitride powder needs to be tested regularly and compared with a preset threshold. If the specific surface area exceeds the limit, the temperature parameters of the oxidizing atmosphere should be adjusted immediately, and the flow rate and purity of the oxidizing atmosphere should be checked to ensure the stability and controllability of the decarbonization process. Through such quality control measures, stable and reliable spherical aluminum nitride powder can be produced, meeting the stringent requirements of high-end electronic devices for thermally conductive fillers.

[0088] Specifically, the reduction in the second preset temperature is directly related to the difference between the specific surface area and the preset specific surface area threshold. It is understood that the adjustment parameter for reducing the second preset temperature can refer to the method for reducing the nitrogen flow rate of the first preset flow rate, which will not be elaborated upon here.

[0089] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing spherical aluminum nitride powder for a thermally conductive filler, characterized by, The method comprises the following steps: S1, obtaining spherical alumina with a preset particle size range and a sintering aid; S2, mixing the spherical alumina with the sintering aid to obtain a mixture; S3, burying the mixture in carbon powder and loading the mixture into a sagger; S4, placing the sagger loaded with the mixture and the carbon powder into a high-temperature calcination furnace for nitrogen atmosphere calcination treatment, and the calcination treatment parameters include a first preset flow of nitrogen, a first preset temperature and a first preset time length; S5, taking the sagger out of the high-temperature calcination furnace, and cooling to room temperature under the first preset flow of nitrogen atmosphere to obtain a spherical aluminum nitride powder primary product; S6, testing the thermal conductivity of the spherical aluminum nitride powder primary product, and preliminarily determining whether the preparation of the spherical aluminum nitride powder primary product meets the preset standard according to the thermal conductivity; if the thermal conductivity is less than a second preset thermal conductivity, it is preliminarily determined that the preparation of the spherical aluminum nitride powder primary product does not meet the preset standard; if the thermal conductivity is greater than or equal to the second preset thermal conductivity, it is determined that the preparation of the spherical aluminum nitride powder primary product meets the preset standard; S7, in response to the preliminary determination that the preparation of the spherical aluminum nitride powder primary product does not meet the preset standard, checking whether the preparation of the spherical aluminum nitride powder primary product meets the preset standard according to the spherical characteristic value of the spherical aluminum nitride powder, and determining the reason why the preparation of the spherical aluminum nitride powder primary product does not meet the preset standard according to the agglomeration index; if the thermal conductivity is less than a first preset thermal conductivity, the reason why the preparation of the spherical aluminum nitride powder primary product does not meet the preset standard is determined according to the agglomeration index; in response to the thermal conductivity being greater than or equal to the first preset thermal conductivity and less than the second preset thermal conductivity, checking whether the preparation of the spherical aluminum nitride powder primary product meets the preset standard according to the spherical characteristic value of the spherical aluminum nitride powder; in response to the thermal conductivity being greater than or equal to the first preset thermal conductivity and less than the second preset thermal conductivity, checking whether the preparation of the spherical aluminum nitride powder primary product meets the preset standard according to the spherical characteristic value of the spherical aluminum nitride powder; in response to the spherical characteristic value being less than a preset spherical characteristic value threshold, it is checked that the preparation of the spherical aluminum nitride powder primary product meets the preset standard; in response to the spherical characteristic value being greater than or equal to the preset spherical characteristic value threshold, it is checked that the preparation of the spherical aluminum nitride powder primary product does not meet the preset standard, and the nitrogen flow of the first preset flow is reduced according to the difference between the spherical characteristic value and the preset spherical characteristic value threshold; S8, in response to determining that the preparation of the spherical aluminum nitride powder primary product meets the preset standard, placing the spherical aluminum nitride powder primary product meeting the preset standard in an oxidizing atmosphere for decarburization treatment to obtain a spherical aluminum nitride powder finished product; the decarburization treatment parameters include a second preset flow, a second preset temperature and a second preset time length; In step S9, the specific surface area of the spherical aluminum nitride powder product is obtained, and whether the carbon removal treatment of the spherical aluminum nitride powder product meets the preset standard is determined according to the specific surface area; if the specific surface area is less than a preset specific surface area threshold, it is determined that the carbon removal treatment of the spherical aluminum nitride powder product meets the preset standard; if the specific surface area is greater than or equal to the preset specific surface area threshold, it is determined that the carbon removal treatment of the spherical aluminum nitride powder product does not meet the preset standard, and the second preset temperature is reduced according to the difference between the specific surface area and the preset specific surface area threshold.

2. The method for producing spherical aluminum nitride powder for a thermally conductive filler according to claim 1, characterized by, The reduction range of the first preset flow rate of nitrogen flow is positively correlated with the difference between the spherical characteristic value and the preset spherical characteristic value threshold. The spherical characteristic value is the ratio of the standard deviation of the diameters of the spherical aluminum nitride powder product in several directions to the average diameter.

3. The method for producing spherical aluminum nitride powder for a thermally conductive filler according to claim 2, characterized by, According to the agglomeration index, the reason why the preparation of the spherical aluminum nitride powder product does not meet the preset standard is determined, wherein, If the agglomeration index is less than a preset agglomeration index threshold, it is determined that the reason why the preparation of the spherical aluminum nitride powder product does not meet the preset standard is that the high-temperature calcination furnace heating rate is not up to standard, and the high-temperature calcination furnace heating rate is increased according to the difference between the preset agglomeration index threshold and the agglomeration index; If the agglomeration index is greater than or equal to the preset agglomeration index threshold, it is determined that the reason why the preparation of the spherical aluminum nitride powder product does not meet the preset standard is that the saggar cooling rate is not up to standard, and the saggar cooling rate is reduced according to the difference between the agglomeration index and the preset agglomeration index threshold; The agglomeration index is the ratio of the number of agglomerates in the spherical aluminum nitride powder product to the total number of particles.

4. The method for producing spherical aluminum nitride powder for a thermally conductive filler according to claim 3, characterized by, The high-temperature calcination furnace heating rate is positively correlated with the difference between the preset agglomeration index threshold and the agglomeration index. The reduction range of the saggar cooling rate is positively correlated with the difference between the agglomeration index and the preset agglomeration index threshold.

5. The method of claim 4, wherein the spherical aluminum nitride powder for a thermally conductive filler is prepared by the steps of: preparing a mixture of aluminum and nitrogen; and heating the mixture to a temperature of 1,000°C or higher in a nitrogen atmosphere. The reduction range of the second preset temperature is positively correlated with the difference between the specific surface area and the preset specific surface area threshold.

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