Method for efficiently preparing titanium nitride through carbothermal reduction and titanium nitride

Abstract

The invention relates to the technical field of titanium nitride preparation, and discloses a method for efficiently preparing titanium nitride through carbothermal reduction and titanium nitride.The method comprises the steps that a titanium-containing raw material, a calcium-containing raw material and a carbonaceous raw material are prepared and ground, and a binder is added into the ground raw materials for mixing to obtain a mixture; pressing the mixture in a ball press machine to obtain raw material balls; the raw material balls are placed in a graphite crucible and fired in a plurality of temperature zones in a pushed slab kiln in sequence, and the temperatures of the plurality of temperature zones are sequentially increased and then decreased. The method is favorable for reducing the production cost and improving the production efficiency, the addition of the calcium-containing compound is favorable for shortening the nitriding time, reducing the nitriding temperature and improving the reaction efficiency, and the mass percent of C and O in the titanium nitride prepared by the method is less than 1%.

Description

Technical Field

[0001] The invention relates to the technical field of titanium nitride preparation, and in particular to a method for efficiently preparing titanium nitride by carbothermal reduction. Background Art

[0002] Titanium nitride (TiN) is an important inorganic material with many advantages and a wide range of applications. The hardness of titanium nitride is about 2000-3000HV, which is 2-3 times that of steel and close to the hardness of diamond, making it an excellent tool material that can efficiently cut and process various materials. Its melting point is as high as 2930℃, and it is not easy to oxidize and corrode in high temperature environments. Therefore, it can be used as a high-temperature coating material to prevent wear and corrosion of mechanical parts at high temperatures. At the same time, titanium nitride can still maintain its hardness and shape in harsh environments such as high temperature, high pressure, and high speed, and is widely used in the field of high wear resistance. Titanium nitride also has certain electrical and thermal conductivity and is a good resistance material. At present, there are various methods for preparing titanium nitride, including physical vapor deposition, chemical vapor deposition, sol-gel, mechanical alloying, thermal decomposition, carbon thermal reduction, etc. Each method has its own specific disadvantages, such as physical vapor deposition (PVD), which requires high vacuum conditions and high equipment costs; particulate contamination is easily generated during the preparation process; chemical vapor deposition (CVD), which requires high temperature and high pressure conditions, high equipment costs, and chemical contamination is easily generated during the preparation process; direct nitridation (such as direct nitridation of metal titanium powder or TiH2), the raw material price is high, batch production is not possible, and the process is prone to powder sintering, resulting in losses. In summary, the methods of the prior art are limited in the production and application of titanium nitride due to various factors such as high cost, low efficiency, complex process, harsh preparation conditions, and difficulty in large-scale preparation.

[0003] Therefore, there is a need in the prior art for improving the method for efficiently preparing titanium nitride by carbothermal reduction. Summary of the invention

[0004] In view of this, the purpose of the embodiments of the present invention is to provide a method for efficiently preparing titanium nitride by carbothermal reduction. The introduction of calcium-containing compounds helps to shorten the nitriding time, reduce the nitriding temperature, and improve the reaction efficiency.

[0005] Based on the above purpose, an embodiment of the present invention provides a method for efficiently preparing titanium nitride by carbothermal reduction, comprising the following steps: Preparing titanium-containing raw materials, calcium-containing raw materials, and carbonaceous raw materials for grinding, and adding a binder to the ground raw materials for mixing to obtain a mixed material; The mixed material is pressed in a ball press to obtain raw material balls; The raw material ball is placed in a graphite crucible and fired in a plurality of temperature zones in a push plate kiln in sequence to obtain titanium nitride, and the temperatures in the plurality of temperature zones are changed in sequence to first increase and then decrease.

[0006] In some embodiments, 100 parts of titanium-containing raw materials contain 0.5 to 1.2 parts of calcium compounds, calculated by the mass of Ca, and the raw materials are mixed at a molar ratio of C:O=1:(1-2).

[0007] In some embodiments, the titanium-containing raw material is titanium dioxide, the calcium-containing raw material includes one or more of calcium carbonate, calcium oxide, and calcium fluoride, and the carbonaceous raw material includes one or more of graphite and carbon black.

[0008] In some embodiments, the amount of binder added is 7% to 12% of the total amount of the ground raw material.

[0009] In some embodiments, the binder is any one of water, a mixed slurry of water and starch, and a mixed slurry of water and glucose.

[0010] In some embodiments, the push plate kiln includes three temperature zones, the temperature range of the first temperature zone is 100-800°C, the maximum temperature of the second temperature zone is 1200-1400°C, and the temperature of the third temperature zone drops from the maximum temperature to room temperature.

[0011] In some embodiments, the nitrogen pressure in the push plate kiln is 20-150 Pa, and the nitrogen flow rate is 1.5 L / min-15 L / min.

[0012] In some embodiments, the heating time in the first temperature zone is 1 to 5 hours, the heating time in the second temperature zone is 3 to 10 hours, and the cooling time in the third temperature zone is 2 to 5 hours.

[0013] In some embodiments, the three raw materials are ground to -200 mesh, and a binder is added and mixed, and the mixing is performed in a wet mixer for 2 to 3 hours.

[0014] On the other hand, the present invention further provides titanium nitride, which is prepared using the method as described above. In the titanium nitride, the mass fraction ratio of N to Ti is 0.18-0.27, and the mass percentages of C and O are less than 1%.

[0015] The present invention has at least the following beneficial technical effects: The present invention provides a method for preparing titanium nitride, which helps to reduce production costs and improve production efficiency. The addition of calcium-containing compounds may interact with other components in the raw materials during the carbon thermal reduction process to form a low-melting point eutectic or promote the formation of certain intermediate products. These changes are conducive to accelerating the reaction rate, thereby shortening the nitriding time. In addition, the addition of calcium-containing compounds may reduce the activation energy of the reaction by changing the reaction path or forming an intermediate phase that is conducive to nitrogen penetration, which means that at a lower temperature, the reactants can obtain enough energy to react, thereby achieving low temperature of the nitriding process. The mass percentage of C and O in the titanium nitride prepared by the method of the present invention is less than 1%. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0016] Figure 1 The present invention provides a flow chart of an embodiment of a method for preparing titanium nitride by carbothermal reduction. DETAILED DESCRIPTION

[0017] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0018] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions; the terms "first", "second", etc. in the specification and claims of the present invention or the above-mentioned drawings are used to distinguish different objects rather than to describe a specific order. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0019] In addition, reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0020] There are various problems in the methods for preparing titanium nitride in the prior art. Specifically, CN201910446227.1 discloses a method for preparing porous titanium nitride, but this method requires long-term ball milling and has low production efficiency; oxidation is easily produced during the preparation process. CN201510005889.7 discloses a method for preparing titanium nitride, but this method has low production efficiency, cannot be industrialized on a large scale, and has high requirements for the control of the composition of raw materials. In summary, there is a need in the prior art to provide a method for preparing titanium nitride that is efficient, easy to industrialize, and can save energy.

[0021] like Figure 1 The method for efficiently preparing titanium nitride by carbothermal reduction provided by the present invention comprises the following steps: S1: preparing titanium-containing raw materials, calcium-containing raw materials, and carbonaceous raw materials for grinding, and adding a binder to the ground raw materials for mixing to obtain a mixture; S2 presses the mixture in a ball press to obtain raw material balls; S3: placing the raw material ball in a graphite crucible and firing it in a plurality of temperature zones in a push plate kiln in sequence to obtain titanium nitride, wherein the temperatures in the plurality of temperature zones are changed in sequence to first increase and then decrease.

[0022] Further, in S1, titanium-containing raw materials, calcium-containing raw materials, and carbonaceous raw materials are prepared in a specific ratio. The titanium-containing raw material is titanium dioxide, the calcium-containing raw material includes one or more of calcium carbonate, calcium oxide, and calcium fluoride, and the carbonaceous raw material includes one or more of graphite and carbon black. Among them, 100 parts of titanium-containing raw materials, based on the mass of Ca, contain 0.5 to 1.2 parts of calcium compounds, and the raw materials are mixed according to the molar ratio of C:O=1:(1~2). The proportion of carbonaceous raw materials is converted according to the oxygen content ratio in the titanium raw material and the calcium raw material. For example, there are 10 mol of oxygen in the titanium raw material and the calcium raw material, and the carbon ratio is between 5 and 10 mol. The three raw materials are ground to pass through a 200-mesh sieve, and then a binder is added to mix to obtain a mixture. The ground material can significantly increase the surface area of ​​the raw material, making the raw material particles finer and more uniform. This is conducive to the full contact and mixing of the raw materials in the subsequent reaction process, thereby improving the reaction efficiency.

[0023] In some embodiments, the binder is any one of water, a mixed slurry of water and starch, and a mixed slurry of water and glucose, and the amount of the binder added is 7% to 12% of the total amount of the raw materials after grinding.

[0024] In some embodiments, the mixing is carried out in a wet mixer for 2 to 3 hours. The wet mixing method can enable better contact and mixing between the raw material particles, thereby improving the mixing uniformity, mixing multiple raw materials evenly together, and avoiding the situation where the local raw material concentration is too high or too low during the reaction, thereby ensuring the consistency and stability of the reaction.

[0025] Furthermore, in S2, the mixed material is pressed in a ball press to obtain raw material balls. By ball pressing, the loose wet mixed raw materials can be compressed into dense spheres, thereby significantly improving the packing density of the raw materials. This is conducive to the raw materials being able to be more closely packed together in the subsequent firing process, reducing gaps and improving reaction efficiency. The formation of raw material balls makes the contact area between the reactants relatively concentrated, which is conducive to the transfer of heat and substances.

[0026] Further, in S3, the push plate kiln includes three temperature zones, the first temperature zone is a low temperature drying zone, the second temperature zone is a high temperature nitriding zone, and the third temperature zone is a low temperature cooling zone. In the low temperature drying zone, the raw material ball is slowly heated to remove internal moisture, reducing cracks or deformation caused by too fast evaporation of moisture, thereby improving the stability of the raw material ball. The high temperature nitriding zone provides a sufficient temperature environment to allow certain elements in the raw material ball to react with nitrogen to form the required nitride. : The raw material ball quickly enters the low temperature cooling zone after the high temperature nitriding zone, which can effectively reduce the temperature gradient, reduce the thermal stress caused by rapid cooling, and avoid product cracking or deformation.

[0027] Among them, the temperature range of the first temperature zone is 100~800℃, the maximum temperature of the second temperature zone is 1200~1400℃, and in some embodiments, the maximum temperature of the second temperature zone can be 1200, 1250, 1300, 1400℃. The third temperature zone is reduced from the maximum temperature obtained in the second temperature zone to room temperature. Specifically, the heating time in the first temperature zone is 1~5h, the heating time in the second temperature zone is 3~10h, and the cooling time in the third temperature zone is 2~5h. The nitrogen pressure in the push plate kiln is 20~150Pa, and the nitrogen flow rate is 1.5L / min~15L / min.

[0028] In the titanium nitride prepared by the method of the present invention, the mass fraction ratio of N to Ti is 0.18-0.27, and the mass percentages of C and O are less than 1%.

[0029] The present invention will be further explained below in conjunction with specific embodiments.

[0030] Example 1 S1 prepares titanium dioxide, CaCO3, and graphite powder for grinding, and adds water as a binder to the ground raw materials to mix to obtain a mixture; S2 presses the mixture in a ball press to obtain raw material balls; S3: placing the raw material ball in a graphite crucible and firing it in multiple temperature zones in a push plate kiln in sequence to obtain titanium nitride.

[0031] Specifically, 100 kg of titanium dioxide, 1.4 kg of CaCO3, and 28 kg of graphite powder were mixed and ground to -200 mesh. 13 kg of water was added as a binder and wet mixed for 2 hours. The ball was pressed by a ball press under a pressure of 8 MPa, and the prepared ball was a biconical structure with thin sides and thick in the middle, wherein the thickest part was 26 mm thick, 44 mm long, and 36 mm wide.

[0032] The material balls are loaded into a graphite crucible and sent to a push plate kiln for firing. The push plate kiln is mainly divided into three temperature zones. Zone 1 is a low-temperature preheating zone with a temperature of 100-800°C and a reaction time of 3h. Zone 2 is a high-temperature nitriding zone with a maximum temperature of 1400°C and a reaction time of 5h. Zone 3 is a low-temperature cooling zone, which is cooled to room temperature and has a cooling time of 2h. A nitrogen atmosphere is introduced into the push plate kiln with a nitrogen flow rate of 8 L / min. Titanium iron nitride is obtained by reaction. The products after the reaction are calculated by mass percentage, of which Ti is 76.5%, N is 18.2%, C is 0.8%, O is 0.9%, and the rest are impurities.

[0033] Example 2 S1 prepares titanium dioxide, calcium oxide, and graphite powder for grinding, and adds water as a binder to the ground raw materials to mix to obtain a mixture; S2 presses the mixture in a ball press to obtain raw material balls; S3: placing the raw material ball in a graphite crucible and firing it in multiple temperature zones in a push plate kiln in sequence to obtain titanium nitride.

[0034] Specifically, 100 kg of titanium dioxide, 1.38 kg of calcium oxide, and 26 kg of graphite powder are mixed and ground to -200 mesh. 12.7 kg of water is added as a binder and wet mixed for 2 hours. After the ball press is pressed under a pressure of 8 MPa, the prepared ball is a double-conical sheet structure with thin sides and thick middle, wherein the thickest part is 26 mm thick, 44 mm long, and 36 mm wide. The ball is loaded into a graphite crucible and sent to a push plate kiln for firing. The push plate kiln is mainly divided into three areas. Area 1 is a low-temperature preheating area with a temperature of 100-800 ° C and a reaction time of 3 hours. Area 2 is a high-temperature nitriding area with a maximum temperature of 1400 ° C and a reaction time of 5 hours. Area 3 is a low-temperature cooling area, cooled to room temperature, and the cooling time is 2 hours. A nitrogen atmosphere is introduced into the push plate kiln, and the nitrogen flow rate is 10 L / min. Titanium ferronitride is obtained by reaction. The product after the reaction is calculated by mass percentage, wherein Ti is 76.8%, N is 19.6%, C is 0.81%, O is 0.83%, and the rest are impurities.

[0035] Example 3 S1: preparing titanium dioxide, calcium fluoride and graphite powder for grinding, adding water and glucose mixture as a binder to the ground raw materials to obtain a mixture; S2 presses the mixture in a ball press to obtain raw material balls; S3: placing the raw material ball in a graphite crucible and firing it in multiple temperature zones in a push plate kiln in sequence to obtain titanium nitride.

[0036] 100 kg of titanium sponge, 1 kg of calcium fluoride, and 27 kg of graphite powder were mixed and ground to -200 mesh. 13.2 kg of water and glucose mixture were added as a binder and wet mixed for 2 hours. The ball was pressed by a ball press under a pressure of 8 MPa. The prepared ball was a biconical structure with thin sides and thick in the middle, with a thickness of 26 mm at the thickest point, a length of 44 mm, and a width of 36 mm.

[0037] The material balls are loaded into a graphite crucible and sent to a push plate kiln for firing. The push plate kiln is mainly divided into three areas. Area 1 is a low-temperature preheating area with a temperature of 100-800°C and a reaction time of 3h. Area 2 is a high-temperature nitriding area with a maximum temperature of 1400°C and a reaction time of 5h. Area 3 is a low-temperature cooling area, which is cooled to room temperature and has a cooling time of 2h. A nitrogen atmosphere is introduced into the push plate kiln with a nitrogen flow rate of 10L / min. Titanium iron nitride is obtained by reaction. The products after the reaction are calculated by mass percentage, of which Ti is 75.8%, N is 19.2%, C is 0.83%, O is 0.85%, and the rest are impurities.

[0038] The present invention provides a method for preparing titanium nitride, which helps to reduce production costs and improve production efficiency. The addition of calcium-containing compounds may interact with other components in the raw materials during the carbon thermal reduction process to form a low-melting point eutectic or promote the formation of certain intermediate products. These changes are conducive to accelerating the reaction rate, thereby shortening the nitriding time. In addition, the addition of calcium-containing compounds may reduce the activation energy of the reaction by changing the reaction path or forming an intermediate phase that is conducive to nitrogen penetration, which means that at a lower temperature, the reactants can obtain enough energy to react, thereby achieving low temperature of the nitriding process. The mass percentage of C and O in the titanium nitride prepared by the method of the present invention is less than 1%. The above are exemplary embodiments disclosed in the present invention, but it should be noted that various changes and modifications may be made without departing from the scope disclosed in the embodiments of the present invention as defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any particular order. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0039] It should be understood that, as used herein, the singular forms "a", "an" are intended to include the plural forms as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations including one or more of the associated listed items.

[0040] The serial numbers of the embodiments disclosed in the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0041] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the above embodiments of the present invention, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A method for efficiently preparing titanium nitride by carbothermal reduction, characterized in that: include: Preparing titanium-containing raw materials, calcium-containing raw materials, and carbonaceous raw materials for grinding, and adding a binder to the ground raw materials for mixing to obtain a mixed material; Pressing the mixture in a ball press to obtain raw material balls; The raw material balls are placed in a graphite crucible and fired in a plurality of temperature zones in a push plate kiln in sequence to obtain titanium nitride, wherein the temperatures of the plurality of temperature zones are sequentially changed to first increase and then decrease.

2. The method for efficiently preparing titanium nitride by carbothermal reduction according to claim 1, characterized in that: The titanium-containing raw material is 100 parts, and the calcium-containing compound is 0.5 to 1.2 parts, calculated by the mass of Ca. The raw materials are mixed in a molar ratio of C:O=1:(1-2).

3. The method for efficiently preparing titanium nitride by carbothermal reduction according to claim 1, characterized in that: The titanium-containing raw material is titanium dioxide, the calcium-containing raw material includes one or more of calcium carbonate, calcium oxide and calcium fluoride, and the carbonaceous raw material includes one or more of graphite and carbon black.

4. The method for efficiently preparing titanium nitride by carbothermal reduction according to claim 1, characterized in that: The amount of the binder added is 7% to 12% of the total amount of the raw materials after grinding.

5. The method for efficiently preparing titanium nitride by carbothermal reduction according to claim 1, characterized in that: The binder is any one of water, a mixture of water and starch, and a mixture of water and glucose.

6. The method for efficiently preparing titanium nitride by carbothermal reduction according to claim 1, characterized in that: The push plate kiln comprises three temperature zones, the temperature range of the first temperature zone is 100-800° C., the highest temperature of the second temperature zone is 1200-1400° C., and the temperature of the third temperature zone drops from the highest temperature to room temperature.

7. The method for efficiently preparing titanium nitride by carbothermal reduction according to claim 1, characterized in that: The nitrogen pressure in the push plate kiln is 20-150 Pa, and the nitrogen flow rate is 1.5 L / min-15 L / min.

8. The method for efficiently preparing titanium nitride by carbothermal reduction according to claim 6, characterized in that: The heating time in the first temperature zone is 1 to 5 hours, the heating time in the second temperature zone is 3 to 10 hours, and the cooling time in the third temperature zone is 2 to 5 hours.

9. The method for efficiently preparing titanium nitride by carbothermal reduction according to claim 1, characterized in that: The three raw materials are ground to -200 mesh, and a binder is added for mixing. The mixing is performed in a wet mixer for 2 to 3 hours.

10. Titanium nitride, prepared by the method according to any one of claims 1 to 9, characterized in that: In the titanium nitride, the mass fraction ratio of N to Ti is 0.18-0.27, and the mass percentages of C and O are less than 1%.

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