Method for preparing Ti2AlN / Al2O3 composite powder by reducing titanium concentrate

Abstract

The invention provides a technical route for preparing high-added-value titanium-based MAX phase composite powder through cooperation of gas-based reduction and titanium nitride concentrate so as to achieve collaborative optimization of efficient utilization of titanium resources and value increase of products. According to the method, the titanium concentrate is used as a raw material, and after drying and screening treatment, NH3 is used as a reducing gas to carry out a reduction nitridation reaction in a horizontal tube furnace. Grinding the reduction nitridation product Ti (N, O), and then carrying out acid leaching, filtering and drying to obtain an acid leaching product; mixing and grinding an acid leaching product and additives Al and Ti powder, sintering in a vertical tube furnace to obtain titanium-based MAX-phase composite powder, and carrying out acid leaching impurity removal to obtain Ti2AlN / Al2O3 composite powder. The method has the advantages of short process flow, simplicity in operation, adoption of carbon-free reduction, low reaction temperature, high added value of products and the like, and provides a new thought for high-value utilization of the titanium concentrate.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, specifically to a method for preparing Ti(N,O) by reduction of titanium concentrate and for synthesizing Ti2AlN / Al2O3 composite powder. Background Technology

[0002] Titanium and titanium alloys, due to their superior properties, are gradually replacing aluminum alloys and steel in the field of advanced industrial structural materials, earning them the title of "the third metal." They influence the development of numerous high-tech industries, including aerospace, marine engineering, biomedicine, chemical energy, and everyday life. With the increasing depletion of natural rutile resources, the global titanium industry is gradually shifting towards the more abundant ilmenite deposits. However, the vast majority of ilmenite in nature has a low TiO2 grade, leading to increased energy consumption and pollution in titanium product manufacturing processes.

[0003] my country's Panzhihua-Xichang region is rich in vanadium and titanium resources, with titanium primarily existing in the form of titanium concentrate. Currently, the electric arc furnace (EAF) smelting method is the most mature titanium slag production process globally. This method uses titanium concentrate as raw material, adding carbonaceous reducing agents such as petroleum coke, coal, or coke to prepare pellets. These pellets are then selectively reduced in an electric arc furnace at 1600–1800℃ to obtain iron and enriched titanium slag. The titanium slag is then used in the sulfuric acid process to produce titanium dioxide. However, as the grade of titanium concentrate decreases, the added value of producing titanium dioxide as a single product also decreases, while energy consumption and pollution further increase.

[0004] To increase the added value of titanium products, research has begun on the reduction of titanium concentrate to prepare Max phase composite materials. Max phase composite materials, as a novel type of ceramic material, combine the excellent properties of both ceramics and metals, exhibiting thermal and electrical conductivity similar to metallic materials and oxidation resistance and high-temperature resistance similar to ceramic materials. Ti-Al based Max phase materials have become the most widely studied and industrially promising Max phase system due to their unique physicochemical properties. However, current synthesis of Ti-Al based Max phases and their composites often uses high-purity titanium powder (purity >99.5%) or secondary compounds (such as TiC, TiN, TiO2, etc.) as titanium-containing raw materials. These raw materials are highly processed end products of the titanium industry, and therefore relatively expensive, which is one of the important reasons for the high cost of preparing Ti-Al based Max phase materials.

[0005] Before synthesizing the MAX phase from titanium concentrate, reduction of the titanium concentrate is generally required. Titanium concentrate reduction typically employs either solid-state reduction or gas-solid reduction processes. The former uses graphite, coke, or similar reducing agents to perform carbothermic solid-state reduction and carbonitriding of the titanium concentrate under Ar or N2 atmospheres. The latter uses CH4-H2 as a reducing agent to prepare titanium carbonitriding products and can achieve efficient reduction at lower temperatures. Driven by the development of new clean energy sources, renewable energy source NH3, which can decompose at high temperatures to produce H2 and N2, is a highly efficient hydrogen energy carrier. It possesses stronger reducing power than H2 and can also provide a nitrogen source for the reaction system, making it a highly promising new reducing agent. Furthermore, first-principles calculations show that increased temperature facilitates the diffusion of NH3 on the (001) surface of FeTiO3 crystals, and the intermediate product of NH3 decomposition, NH... x (x=0-3) and H tend to adsorb at Fe and O sites, which is conducive to the deoxygenation reaction. This phenomenon indicates that the presence of metallic iron can promote the reductive nitridation process of metal oxides by NH3.

[0006] Therefore, this study investigates a process for preparing Ti(N,O) carbon and nitrogen compounds by reducing titanium concentrate with NH3, followed by sintering to prepare MAX phase Ti2AlN / Al2O3 composite powder. The aim is to address issues such as insufficient high-value utilization of titanium concentrate, high cost of MAX phase raw materials, and large carbon emissions from traditional reduction processes. Summary of the Invention

[0007] To address the aforementioned shortcomings in the existing technology, the present invention aims to provide a method for preparing Ti(N,O) by reduction of titanium concentrate and for synthesizing Ti2AlN / Al2O3 composite powder.

[0008] To achieve the above objectives, the present invention employs the following process: a method for preparing Ti(N,O) by reduction of titanium concentrate and synthesizing Ti2AlN / Al2O3 composite powder, comprising the following steps:

[0009] S0: Pre-oxidation step: Titanium concentrate powder is calcined in air to obtain pre-oxidized titanium concentrate; the calcination temperature is 850-900℃, and the holding time is 3-5 hours. Pre-oxidation treatment of titanium concentrate is used to improve the rate of the reduction nitriding reaction.

[0010] S1: Pre-oxidized titanium concentrate is dried at 100℃ for at least 12 hours, ground and sieved to a particle size of 100–150 μm, and then subjected to a reduction nitriding reaction at 1100–1200℃ for 1–8 hours under an NH3 atmosphere to obtain the reduction nitriding product Ti(N,O). The titanium concentrate is ground and then dried in an oven at 100℃ for at least 12 hours to remove moisture, and sieved to obtain titanium concentrate raw material with a particle size of 100–150 μm. The raw material is placed in a corundum crucible and subjected to reduction nitriding under an NH3 atmosphere to obtain the reduction nitriding product Ti(N,O). The reduction nitriding reaction time is 1–8 hours, and the temperature is 1100–1200℃.

[0011] S2: The reduced nitrided product Ti(N,O) obtained in S1 is ground and mixed, and then acid-leached in dilute hydrochloric acid leaching solution. After filtration, it is placed in an oven and dried at 100℃ for more than 12 hours to remove moisture and obtain the acid-leached product.

[0012] S3: The acid-leached product obtained in S2 is ground and mixed with additives Al or Ti, then pressed into briquettes. The molar ratio of the acid-leached product to additives Al and Ti is (0.8-1.2):(1.3-2):1. Sintering is carried out under an inert gas atmosphere, followed by natural cooling and grinding to obtain MAX phase composite powder. This powder is then purified by acid leaching with dilute hydrochloric acid to obtain Ti2AlN / Al2O3 composite powder. Specifically, Ar gas is introduced into a vertical tube furnace for sintering, followed by natural cooling and grinding to obtain MAX phase composite powder. This powder is then purified by acid leaching to obtain Ti2AlN / Al2O3 composite powder.

[0013] Furthermore, the pre-oxidation step of SO can improve the rate of the reduction nitridation reaction. The pre-oxidation treatment is carried out at a temperature of 900°C for 4 hours in an air atmosphere.

[0014] Furthermore, in the S1 reduction reaction, the reduction gas flow process involves introducing Ar gas at a rate of 500 sccm for 30 minutes before heating to purge the air from the furnace. Then, under the protection of flowing Ar gas, the temperature is raised to 1100-1200℃. The reduction heating program is as follows: the heating rate is 5-10℃ / min. After reaching the predetermined temperature, the Ar gas is turned off, and NH3 is introduced at a flow rate of 200 sccm. Finally, after the holding period, the NH3 is switched to Ar gas at a flow rate of 200-500 sccm, and the temperature is lowered to 800℃ at a cooling rate of 5℃ / min before naturally cooling to room temperature with the furnace.

[0015] Furthermore, in S2 and S3, the concentration of dilute hydrochloric acid as the leaching medium is 2-4 mol / L, the acid leaching liquid-to-solid ratio is 8-12 mL / g, the stirring temperature is 45-55℃, and the leaching time is 1-3 hours. Preferably, the concentration of dilute hydrochloric acid as the acid leaching medium is 3 mol / L, the liquid-to-solid ratio is 10 mL / g, the reaction time is 2 hours, the reaction temperature is 50℃, and the reaction requires stirring.

[0016] Furthermore, in S3, to eliminate the influence of impurities in the Ti(N,O) powder on its molar mass when calculating the amount of ingredients, a uniform molar mass of 62 g / mol of Ti(N,O) powder is used. The S3 reduction heating program is as follows: before heating, Ar gas is introduced at a rate of 500 sccm for 30 min to purge the air in the furnace. Then, under the protection of flowing Ar gas, the temperature is raised and held. During the heating and holding process, the flow rate of Ar gas is 150 sccm. The temperature is raised to 1300-1500℃ under the protection of flowing Ar gas and held. During the heating and holding process, the flow rate of Ar gas is 150 sccm. The heating rate is 5-10℃ / min below 1000℃, specifically 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min; 5-10℃ / min in the range of 1000-1400℃, specifically 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min; and 2-5℃ / min above 1400℃, specifically 2℃ / min, 3℃ / min, 4℃ / min or 5℃ / min. After the holding time is completed, the temperature is reduced at a rate of 2-5℃ / min within the range of 1400-1500℃, and 5-10℃ / min below 1400℃. Specifically, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min can be selected. After the temperature drops to 800℃, the furnace is allowed to cool naturally to room temperature.

[0017] Compared with the prior art, the present invention has at least the following advantages:

[0018] 1. Electric arc furnace smelting of low-grade titanium concentrate raw materials suffers from high energy consumption and carbon emissions. This invention utilizes NH3 as a highly efficient hydrogen carrier. Under high-temperature conditions, NH3 can dissociate to generate highly reactive intermediates such as N, NH, and NH2, which have stronger reducing power than H2. It can also provide a nitrogen source for the reaction system, eliminating the need for additional N2 introduction, thus simplifying the process and reducing energy consumption.

[0019] 2. The high content of impurities such as CaO and MgO in titanium slag produced by electric arc smelting prevents its direct use in high-end industries, limiting its application to titanium dioxide production via the sulfuric acid process. This invention addresses this issue by resolving the trace amounts of CaO, MgO, and SiO2 in the titanium concentrate reduction-nitridation products. These trace amounts not only do not hinder the synthesis of the Ti-Al MAX phase but also positively contribute to its performance improvement. Therefore, low-cost titanium concentrate can directly replace high-purity titanium powder in the preparation of high-value-added Ti2AlN / Al2O3 composite powder, achieving a "low-in, high-out" approach to titanium resource utilization.

[0020] 3. By adjusting the reduction temperature and time, sintering temperature, time and material ratio, this invention can precisely control the purity of Ti(N,O) and the content of Ti2AlN, resulting in high product stability. Attached Figure Description

[0021] Figure 1 This is a simplified diagram of the process method of the present invention.

[0022] Figure 2 This is the XRD pattern of titanium concentrate raw material.

[0023] Figure 3 The images are SEM images of titanium concentrate raw materials, where (a) and (b) represent SEM images at different magnifications.

[0024] Figure 4 The XRD pattern is shown for the product of titanium concentrate reduced at 1200℃ for 6 hours.

[0025] Figure 5 The images show the SEM and EDS images of the product obtained from the reduction of titanium concentrate at 1200℃ for 6 hours.

[0026] Figure 6 The image shows the XRD pattern of the sintered product after sintering at 1500℃ for 4 hours before acid leaching.

[0027] Figure 7 This is a SEM image of the sintered product after acid leaching and sintering at 1500℃ for 4 hours.

[0028] Figure 8 SEM images of the sintered products after acid leaching and sintering at 1500℃ for 4 hours are shown, where (a) and (b) are before acid leaching, and (c) and (d) are after acid leaching.

[0029] in Figure 2 , Figure 4 , Figure 6 and Figure 7 The horizontal axis represents the diffraction angle 2θ, and the vertical axis represents the intensity of the diffraction peak. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings.

[0031] A method for preparing Ti2AlN / Al2O3 composite powder by reduction of titanium concentrate includes the following steps:

[0032] S1: The titanium concentrate powder is roasted in air atmosphere to obtain pre-oxidized titanium concentrate; wherein the roasting temperature is 850-900℃ and the holding time is 3-5 hours. The roasting temperature can be selected as 850℃, 880℃ or 900℃, and the holding time can be selected as 3h, 4h or 5h.

[0033] S1: After drying the pre-oxidized titanium concentrate at 100℃ for more than 12 hours, grind and sieve it to a particle size of 100-150 μm and place it in an alumina crucible. Reduce and nitridate the ore under an NH3 atmosphere to obtain the reduced nitriding product Ti(N,O). The reduction reaction temperature is 1100–1200℃, and the reduction nitriding reaction time is 1–8 hours. Specifically, the reduction time can be selected as 1 hour, 3 hours, 6 hours, or 8 hours; the reduction temperature can be selected as 1100℃, 1150℃, or 1200℃.

[0034] S2: The reduced nitrided product Ti(N,O) obtained in S1 is ground and mixed, and then acid-leached in dilute hydrochloric acid leaching solution. After filtration, it is placed in an oven and dried at 100℃ for more than 12 hours to remove moisture and obtain the acid-leached product.

[0035] S3: The acid leaching product obtained in S2 is ground and mixed with additives, then pressed into a block and placed in a corundum crucible. Ar gas is introduced into the vertical tube furnace for sintering. After natural cooling, it is ground to obtain MAX phase composite powder. After acid leaching to remove impurities, Ti2AlN / Al2O3 composite powder is obtained. The molar ratio of acid leaching product to additives Al and Ti is (0.8-1.2):(1.3-2):1. Specifically, the molar ratio of Ti(N,O):Ti(N,O):Al:Ti can be 0.8:2:1, 0.9:2:1, 1.0:2:1, 1.1:2:1 or 1.2:2:1; the molar ratio of Al:Ti(N,O):Al:Ti can be 0.9:1.3:1, 0.9:1.5:1, 0.9:1.7:1 or 0.9:1.9:1; the sintering temperature is 1300℃, 1400℃ or 1500℃; and the sintering time is 1h, 2h or 4h.

[0036] Specifically, the SO pre-oxidation process is as follows: the pre-oxidation temperature is 900℃, the time is 4 hours, and the atmosphere is air.

[0037] Specifically, the reduction gas circulation process of S1 is as follows: Before heating, Ar gas is introduced at a rate of 500 sccm for 30 minutes to purge the air from the furnace. Then, under the protection of flowing Ar gas, the temperature is increased at a rate of 10℃ / min below 1000℃ and 5℃ / min above 1000℃. After reaching the predetermined temperature of 1100℃, 1150℃, or 1200℃, the Ar gas is turned off and NH3 is introduced at a flow rate of 200 sccm. Finally, after the holding period, the NH3 is switched to Ar gas at a flow rate of 500 sccm, and the temperature is reduced to 800℃ at a rate of 5℃ / min before the furnace is allowed to cool naturally to room temperature.

[0038] Specifically, the acid leaching conditions for S2 are: dilute hydrochloric acid concentration of 3 mol / L, liquid-to-solid ratio of 10 mL / g, reaction time of 2 h, and stirring at a constant temperature of 50 °C.

[0039] Specifically, the sintering heating process for sample S3 was as follows: Before heating, Ar gas was introduced at a rate of 500 sccm for 30 minutes to purge the air from the furnace. Then, heating and holding were carried out under the protection of flowing Ar gas, with the Ar gas flow rate at 150 sccm during the heating and holding processes. Heating was performed to 1300, 1400, or 1500℃, with a heating rate of 10℃ / min below 1000℃, 5℃ / min in the 1000-1400℃ range, and 2℃ / min in the 1400-1500℃ range. After the holding time, cooling was carried out at a rate of 2℃ / min within the 1400-1500℃ range, and 5℃ / min below 1400℃. After cooling to 800℃, the furnace was allowed to cool naturally to room temperature.

[0040] Specifically, when calculating the batching for sample S3, to eliminate the influence of impurities in the Ti(N,O) powder on its molar mass, a uniform 62 g / mol was used as the molar mass of the Ti(N,O) powder. The sintering conditions were 1500℃ and a reaction time of 4 h. When studying the Ti(N,O) ratio, the Al:Ti molar ratio was fixed at 2:1; when studying the Al ratio, the Ti(N,O):Ti molar ratio was fixed at 0.9:1; when studying the effect of temperature, the Ti(N,O):Al:1Ti molar ratios were selected as 0.9:1.3:1 and 0.9:1.7:1, with a sintering time of 4 h; when studying the effect of time, the Ti(N,O):Al:1Ti molar ratios were selected as 0.9:1.3:1 and 0.9:1.7:1, with sintering at 1500℃.

[0041] Specifically, the Max phase sample obtained by S3 sintering was acid-leached to remove impurities using dilute hydrochloric acid with a concentration of 3 mol / L for 2 hours.

[0042] The present invention will now be described in further detail with reference to the accompanying drawings and specific examples.

[0043] The main chemical components of the titanium concentrate from Panzhihua are shown in Table 1.

[0044] Table 1. Chemical composition analysis of Panzhihua titanium concentrate (wt.%)

[0045]

[0046] Its XRD pattern is as follows Figure 2 As shown, the main phases of the titanium concentrate are titanium FeTiO3 and MgTiO3, with trace amounts of MgO and SiO2 that are difficult to detect. Its SEM image is shown below. Figure 3 As shown, the titanium concentrate particles have a smooth and dense block structure, and the internal structure of the particles is also relatively dense, with no obvious voids or cracks.

[0047] Example 1: A method for preparing Ti2AlN / Al2O3 composite powder by reduction of titanium concentrate, the specific steps of which are as follows:

[0048] S1 titanium concentrate pre-oxidized at 900℃ in air for 4 hours was sieved to obtain titanium concentrate raw material with a particle size of 100μm. 1g of the raw material was weighed and placed in a corundum crucible in the middle isothermal section of a horizontal tube furnace for reduction nitridation. Before heating, Ar gas was introduced at a rate of 500 sccm for 30 min to purge the air from the furnace. Then, under the protection of flowing Ar gas, the temperature was increased at a rate of 10℃ / min below 1000 sccm and 5℃ / min above 1000℃. After reaching 1200℃, the Ar gas was stopped, and NH3 was introduced at a flow rate of 200 sccm. Finally, after holding at this temperature for 6 hours, the NH3 was replaced with Ar gas at 500 sccm, and the temperature was reduced to 800℃ at a rate of 5℃ / min before naturally cooling to room temperature with the furnace. The product at room temperature was then ground and mixed for characterization and analysis. Its XRD pattern is shown below. Figure 4 As shown, the main phases of the reduced nitridation products are Fe and Ti(N,O) phases. Their SEM and EDS images are shown below. Figure 5 As shown, the product particles exhibit a broken and porous morphology. EDS surface scan results revealed that some Fe-enriched areas highly overlap with the Ti / N element distribution.

[0049] The reduced nitriding product Ti(N,O) taken out after S2 cooling to room temperature is ground and mixed together and placed in a beaker. Under the conditions of acid leaching with dilute hydrochloric acid concentration of 3mol / L, liquid-to-solid ratio of 10mL / g, reaction time of 2h, and reaction temperature of 50℃, the mixture is stirred at a constant temperature. After the reaction is completed, the mixture is filtered and placed in an oven to dry at 100℃ for more than 12h to remove moisture and obtain the acid-leached product.

[0050] S3 was added to the acid-leached product Ti(N,O) at a molar ratio of Ti(N,O):Al:Ti of 0.9:1.7:1, along with Al and Ti additives. After grinding and mixing, the mixture was placed in an alumina crucible and sintered in the isothermal section of a vertical tube furnace. Before heating, Ar gas was introduced at a rate of 500 sccm for 30 min to purge the air from the furnace. Then, under the protection of flowing Ar gas, the temperature was raised to 1500℃ and held. During heating and holding, the Ar gas flow rate was 150 sccm. The heating rate was 10℃ / min below 1000℃, 5℃ / min in the 1000-1400℃ range, and 2℃ / min in the 1400-1500℃ range. After holding for 4 hours, the temperature was lowered at a rate of 2℃ / min in the 1400-1500℃ range, and 5℃ / min below 1400℃. After cooling to 800℃, the furnace was allowed to cool naturally to room temperature.

[0051] The sintered sample at room temperature was ground to obtain MAX phase powder. After acid leaching to remove impurities, Ti2AlN / Al2O3 composite powder was obtained, and the phase composition of the powder was characterized and analyzed. The XRD pattern of the sintered product before acid leaching is shown below. Figure 6 As shown in the XRD pattern, the main phase is Ti₂AlN, the minor phases are Ti₄AlN₃, Al₃Ti, and trace amounts of Al₂O₃. The XRD pattern of the product after acid leaching is shown below. Figure 7 As shown, XRD indicates that the diffraction peaks of the Ti3Al phase have largely disappeared. SEM images of the sintered products before and after acid leaching are shown below. Figure 8 As shown, before acid leaching: SEM images reveal that it mainly consists of multi-layered plate-like Ti2AlN blocks, covered with a smooth Al3Ti phase, and numerous irregular submicron-sized Ti2AlN / Al2O3 mixed particles in aggregated clusters. After acid leaching: The Al3Ti phase on the product surface is selectively corroded and dissolved by hydrochloric acid, and some Ti2AlN undergoes interlayer delamination due to the loss of the Al3Ti binder phase.

[0052] Examples 2-3 used the same preparation method as Example 1, the only difference being the selection of process parameters, as shown in Table 2.

[0053] Table 2

[0054]

[0055] The phase characterization results of the reduced nitriding products Ti(N,O) obtained in Examples 1-6 and the sintered Ti2AlN / Al2O3 composite powder are shown in Table 3.

[0056] Table 3

[0057]

[0058] Table 3 shows that although the experimental results of the seven sets of embodiments differed slightly under different process parameter settings, they all met the conditions and standards of the method of the present invention. The results of the seven sets of embodiments demonstrate that, within the relevant process parameter range, the present invention can precisely control the phase composition of the reduction nitridation and sintering products of titanium concentrate by adjusting the reduction temperature, reduction time, Ti(N,O):Al:Ti ratio, sintering temperature, and sintering time, thereby precisely controlling the reduction nitridation products Fe,Ti(N,O) and Ti2AlN / Al2O3 composite powders.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the technical requirements of the present invention.

Claims

1. A method for preparing Ti2AlN / Al2O3 composite powder by reduction of titanium concentrate, characterized in that it includes the following steps: S0: The titanium concentrate powder is calcined in air atmosphere to obtain pre-oxidized titanium concentrate; wherein the calcination temperature is 850-900℃ and the holding time is 3-5 hours. S1: The pre-oxidized titanium concentrate is dried for more than 12 hours, ground and sieved to a particle size of 100-150μm, and then subjected to a reduction nitriding reaction at 1100-1200℃ for 1-8 hours under NH3 atmosphere to obtain the reduction nitriding product Ti(N,O). S2: The reduced nitridation product Ti(N,O) obtained in S1 is ground and mixed, then acid-leached in dilute hydrochloric acid leachate, filtered and dried for more than 12 hours to remove moisture to obtain the acid-leached product. S3: The acid leaching product obtained in S2 is ground and mixed with additives Al and Ti, and then pressed into blocks. The molar ratio of acid leaching product to additives Al and Ti is (0.8-1.2):(1.3-2):

1. Sintering is carried out in an inert gas atmosphere at a sintering temperature of 1300-1500℃ for 1-4 hours. After natural cooling, the blocks are ground to obtain MAX phase composite powder. Then, the powder is removed by acid leaching with dilute hydrochloric acid to obtain Ti2AlN / Al2O3 composite powder.

2. The method for preparing Ti2AlN / Al2O3 composite powder by reducing titanium concentrate according to claim 1, characterized in that: The S1 reduction heating program is as follows: the heating rate is 10℃ / min below 1000℃ and 5℃ / min above 1000℃; after reaching the predetermined temperature, the Ar gas is disconnected and NH3 is introduced at a flow rate of 200 sccm; finally, after the heat preservation is completed, the NH3 is switched to Ar gas at a flow rate of 200-500 sccm, and the temperature is reduced to 800℃ at a cooling rate of 5℃ / min before naturally cooling to room temperature with the furnace.

3. The method for preparing Ti2AlN / Al2O3 composite powder by reducing titanium concentrate according to claim 1, characterized in that: In S2 and S3, the concentration of dilute hydrochloric acid is 2-4 mol / L, the acid leaching solution-to-solid ratio is 8-12 mL / g, the stirring temperature is 45-55℃, and the leaching time is 1-3 hours.

4. The method for preparing Ti2AlN / Al2O3 composite powder by reducing titanium concentrate according to claim 1, characterized in that: The S3 reduction heating program is as follows: under the protection of flowing Ar gas, the temperature is raised to 1300-1500℃ and held. During the heating and holding process, the flow rate of Ar gas is 150 sccm. The heating rate is 10℃ / min below 1000℃, 5-10℃ / min in the range of 1000-1400℃, and 2-5℃ / min above 1400℃. After the holding time is completed, the temperature is lowered at a rate of 2-5℃ / min in the range of 1400-1500℃, and 5-10℃ / min below 1400℃. After the temperature drops to 800℃, the furnace is allowed to cool naturally to room temperature.

5. A synthetic Ti2AlN / Al2O3 composite powder, characterized by: Obtained by the preparation method according to any one of claims 1-4.

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