Method for preparing titanium carbonitride powder by secondary sintering method
Through the secondary sintering method, the problem of limited production capacity of carbon tube furnaces is solved through the combination of presintering and secondary sintering, and high-efficiency production of high-quality titanium carbonitride powder is achieved, reducing equipment costs and land occupation, and improving production efficiency.
Patent Information
- Application Number
- CN202510624900.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-15
- Publication Date
- 2025-08-08
AI Technical Summary
When preparing titanium carbon nitride powder, it is difficult to improve production capacity while ensuring product quality. The equipment covers a large area and is costly, and the capacity of graphite boats is limited.
The secondary sintering method is used to react the titanium dioxide and carbon black mixture at 1400~1600℃ through the presintering stage to generate the presintering material, and then the secondary sintering is performed at 1700~1900℃ to increase the amount of graphite boat loading and optimize the nitrogen flow, and the boat pushing speed is 50~70 minutes/boat.
It has increased the production capacity of a single graphite carbon tube furnace, reduced the equipment footprint and cost, reduced the operator's needs, and improved product quality and production efficiency.
Smart Images
Figure CN120440848A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for preparing titanium carbonitride powder, in particular to a method for preparing titanium carbonitride powder by using a secondary sintering method. Background Art
[0002] Titanium carbonitride is a new titanium-based hard material with high-temperature resistance, high hardness, corrosion resistance, and oxidation resistance. It is the basic material for manufacturing titanium-based cermets. Compared with traditional tungsten carbide-based cermets, it has the advantages of lighter weight and lower price, making it widely used.
[0003] There are various methods for producing titanium carbonitride. In actual production, the most common method is the titanium dioxide carbothermal reduction method, which offers advantages such as high production capacity, stable quality, and low cost. The basic steps for producing titanium carbonitride powder using the titanium dioxide carbothermal reduction method include mixing, drying, loading into boats, sintering, crushing, pulverizing, quality inspection, and packaging. The mixing process typically involves mixing titanium dioxide and carbon black. Of the eight steps mentioned above, sintering is a critical process, and the setting and execution of each parameter in this process impact product quality and production capacity. The existing process utilizes a single-shot sintering method, using a graphite carbon tube furnace as the sintering equipment. The mixed powder is quantitatively loaded into a semicircular graphite boat and introduced into the furnace chamber through the front furnace tube opening. The front furnace door is closed, and a boat pusher system pushes the boat toward the rear furnace tube. After pushing one boat, the push rod is pulled back to open the front furnace door, and another boat is added. The front furnace door is closed, and the boat pusher is repeated, continuously moving the boat toward the rear furnace tube. In the high-temperature section of the furnace, the titanium dioxide in the mixture reacts with the carbon powder and the nitrogen introduced into the furnace to form a sintered titanium carbonitride. The rear furnace door is opened regularly to remove the graphite boat and collect and store the finished product.
[0004] Under existing technical conditions, the equipment used in other processes can be increased in capacity by increasing the equipment specifications, but this is not the case with carbon tube furnaces. The material (mixed powder of titanium dioxide and carbon black) has a small specific gravity, not exceeding 0.5 g / cm 3 , the amount of graphite boat loaded is small, and the finished product obtained after sintering is small. The reaction formula of titanium dioxide carbon thermal reduction method is as follows:
[0005] TiO2+ 5 / 2 C + 1 / 4 N2= 1 / 2 TiC + 1 / 2 TiN + 2 CO ↑ It can be calculated that the theoretical yield of titanium carbonitride is 55.4% of the mixture. Therefore, using the one-step process of carbon thermal reduction of titanium dioxide, the production capacity of a single carbon tube furnace is limited by the amount of material loaded in the graphite boat, that is, the diameter Φ of the furnace tube. However, the diameter Φ of the furnace tube cannot be arbitrarily enlarged. It is limited by the maximum supply size of its processing material. At present, the outer diameter of the electrode graphite parts available for making furnace tubes is 40 cm, so the diameter of the furnace tube is limited. In addition, the method of trying to increase production capacity by increasing the pushing speed is also limited by the insulation time of the material at the reaction temperature. The pushing speed cannot change significantly, otherwise it will affect the product quality.
[0006] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the Invention
[0007] The present invention aims to provide a method for preparing titanium carbonitride powder by a double sintering method, which solves the problem that it is difficult to increase the production capacity while ensuring the quality when sintering titanium carbonitride powder in existing carbon tube furnaces. By using two sintering processes, the loading amount of the graphite boat is increased, the production capacity of a single graphite carbon tube furnace is increased, and the quality of the titanium carbonitride powder is guaranteed.
[0008] In order to achieve the above object, the present invention provides a method for preparing titanium carbonitride powder by a secondary sintering method, the method comprising the following steps: (1) Pre-sintering stage A mixture of titanium dioxide and carbon black in a mass ratio of 1:(0.3-0.4) is placed in a container and placed in a heating device. Nitrogen is passed through the container and heated at 1400-1600°C. After the center temperature of the material reaches the set temperature, the reaction is complete. After the reaction is completed, the material is cooled and taken out of the furnace to obtain a pre-burned material. (2) Pre-burning material mixing stage Mixing the pre-burned materials uniformly; (3) Secondary sintering stage The mixed pre-sintered material is added to a graphite boat, which is then placed in a carbon tube furnace and sintered with nitrogen. The sintering temperature is 1700-1900°C, and the boat pushing speed is 50-70 minutes per boat. The sintered material after being taken out of the furnace is a titanium carbonitride sintered product, which is then crushed to obtain a titanium carbonitride powder product.
[0009] Preferably, in step (1), the nitrogen flow rate is 1.0-1.5 L / min per kilogram of charge to ensure a slightly positive pressure in the heating device; in step (2), the nitrogen flow rate is 2.0-3.0 L / min per kilogram of charge. The nitrogen flow rate in step (2) is determined based on the production of different brands of titanium carbonitride powder.
[0010] Preferably, in step (1), the device for the pre-sintering stage is selected from any one of an electric furnace, a tunnel furnace, a pusher furnace, a rotary furnace, and a tubular furnace. The selection of the pre-sintering equipment mainly considers efficiency and ease of operation. More preferably, a rotary kiln is used, which has high efficiency and is easy to operate. Other types of furnaces are more complicated to load and unload.
[0011] Preferably, in step (1), the reaction time is 1 to 2 hours.
[0012] Preferably, in step (1), heating is performed at a temperature of 1400-1500°C.
[0013] Preferably, in step (2), the pre-burned materials are mixed using a mixer.
[0014] Preferably, in step (3), the diameter Φ of the carbon tube furnace is 128-220 mm, and the length of the graphite boat is 300-500 mm. The outer diameter of the graphite boat used in the present invention may also be larger than the existing outer diameter Φ128 mm. After the pre-sintering process, the middle component of the pre-sintered material is already titanium carbonitride, and the temperature, nitrogen flow rate, and reaction time required for subsequent sintering are reduced, which can improve the problems caused by only using a graphite boat with an increased outer diameter.
[0015] The method of preparing titanium carbonitride powder by a secondary sintering method of the present invention solves the problem that it is difficult to increase production capacity while ensuring quality in the sintering preparation of titanium carbonitride powder using existing graphite carbon tube furnaces, and has the following advantages: (1) The method of the present invention adopts a secondary sintering process, which greatly reduces the weight and volume of materials through pre-sintering. In the secondary sintering, the loading amount of the graphite boat can be increased, and the quality of the product is guaranteed. The production capacity of a single graphite carbon tube furnace is increased, and the production capacity of a single sintering equipment is doubled; (2) The life of a carbon tube furnace is about 3 to 4 months. Each set of carbon tubes and accessories costs 6,000 to 8,000 yuan, depending on the type of furnace. This amounts to about 20,000 yuan per year. The cost of the product's graphite boat is about 2 yuan per kg. With an annual output of 10 tons, the cost of the graphite boat is 20,000 yuan. Each furnace consumes 40,000 yuan of graphite parts per year, and 50 furnaces cost about 2 million yuan. The area required for installation, production, and water and electricity support for each carbon tube furnace is about 60 square meters, and 50 furnaces cost about 3,000 square meters. The method of the present invention can reduce the number of installed graphite carbon tube furnaces by 50%. Calculated at RMB 300,000 per set, the investment in a production line with an annual production capacity of 1,000 tons can be reduced by more than RMB 15 million. Graphite consumables such as graphite boats and carbon tubes can be reduced by 50%, and the cost of a production line with an annual production capacity of 1,000 tons can be reduced by more than RMB 2 million. The area occupied by sintering equipment can be reduced by 50%, and the area occupied by a production line with an annual production capacity of 1,000 tons can be reduced by 3,000 square meters. The number of sintering operators can be reduced by 30%, and the number of sintering operators in a production line with an annual production capacity of 1,000 tons can be reduced by 30%. The maintenance cost of sintering equipment can be reduced by 50%, and the cost of supporting environmental protection and safety facilities and management of sintering equipment can be reduced by 50%. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is the phase analysis diagram of the material of the present invention at different temperatures.
[0017] Figure 2 This is an electron microscope image of the pre-sintered material obtained by pre-sintering in Example 2 of the present invention.
[0018] Figure 3 This is an electron microscope image of the finished product obtained by secondary sintering in Example 1 of the present invention.
[0019] Figure 4 This is an electron microscope image of the finished product obtained by single sintering in Comparative Example 4 of the present invention. DETAILED DESCRIPTION
[0020] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.
[0021] It should be noted that if specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer shall be followed. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.
[0022] Throughout this disclosure, all features, such as values, amounts, amounts, and concentrations, specified in numerical ranges or percentage ranges are provided for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to encompass and specifically disclose all possible subranges and individual values within those ranges (including integers and fractions).
[0023] The features described in this disclosure may be combined in any manner, and as long as there are no conflicts between the combinations of these features, all possible combinations should be considered within the scope of this specification. Each feature disclosed in this specification may be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the features disclosed are merely general examples of equivalent or similar features.
[0024] The present invention provides a method for preparing titanium carbonitride powder by a secondary sintering method, the method comprising the following steps: (1) Pre-sintering stage A mixture of titanium dioxide and carbon black at a mass ratio of 1:(0.3-0.4) is placed in a container and placed in a heating device. Nitrogen is introduced and heated at 1400-1600°C. After the center temperature of the material reaches the set temperature, the reaction is complete. After the reaction is complete, the material is cooled and removed from the furnace to obtain a pre-burned material. The ratio of titanium dioxide to carbon black is within the range of 1:(0.3-0.4) and can be adjusted to meet product requirements based on the carbon and nitrogen content requirements of the product. (2) Pre-burning material mixing stage Mixing the pre-burned materials uniformly; (3) Secondary sintering stage The mixed pre-sintered material is added to a graphite boat, which is then placed in a carbon tube furnace and sintered with nitrogen. The sintering temperature is 1700-1900°C, and the boat pushing speed is 50-70 minutes per boat. The sintered material after being taken out of the furnace is a titanium carbonitride sintered product, which is then crushed to obtain a titanium carbonitride powder product.
[0025] The present invention achieves a doubling of production capacity by adding a pre-sintering process at 1400-1600°C during the titanium carbonitride sintering process. This allows for a moderate reaction of the materials, a high weight loss rate, and a significant volume reduction, thereby increasing the unit charge of the graphite boat. Furthermore, the pre-sintering temperature is between 1400-1600°C, which is lower than that of the primary sintering process, thus achieving energy savings. Furthermore, the pre-sintering furnace offers a wide range of options, a low rated temperature not exceeding 1600°C, low cost, ease of use, and low operating costs. Furthermore, the larger furnace chamber or longer insulation section allows for high production capacity and high production efficiency.
[0026] Specifically, any one of an electric heating furnace, a tunnel furnace, a push plate furnace, a rotary furnace and a tubular furnace may be used, which are conventional products known in the art.
[0027] The following describes in detail a method for preparing titanium carbonitride powder by a secondary sintering method provided by the present invention through examples and comparative examples.
[0028] Example 1 A method for preparing titanium carbonitride powder by a secondary sintering method, using a carbon tube furnace, the diameter of the carbon tube furnace is 168 mm, and the length of a graphite boat is 400 mm. The method comprises the following steps: (1) Pre-sintering stage A 300g mixture of titanium dioxide and carbon black (hereinafter referred to as the material) was placed on a tray, with a mass ratio of titanium dioxide to carbon black ranging from 1:(0.3-0.4) and placed into a tube furnace. Nitrogen (99.999% purity) was introduced at a flow rate of 1.0L / min per kilogram of material to ensure a slight positive pressure within the tube furnace. The mixture was heated to 1400°C. Once the center temperature of the material reached the set temperature, it was held for 60 minutes. After sufficient reaction, it was cooled and removed from the furnace at room temperature, yielding 172g of pre-sintered material.
[0029] (2) Pre-burning material mixing stage Add the above-obtained pre-burned material into a blender and mix until it is uniform; (3) Secondary sintering stage The mixed pre-sintered material is added to a graphite boat, filled to the brim, and then placed in a graphite carbon tube furnace for sintering at a temperature of 1880-1920°C, a nitrogen flow rate of 3.0 L / min, and a boat push speed of 60 min / boat. The sintered material after exiting the furnace is the titanium carbonitride sintered product, which is then crushed to produce the finished titanium carbonitride powder, i.e., TiCN55.
[0030] In the secondary sintering stage, the pre-sintered material (containing carbon, titanium carbonitride and titanium oxide) reacts with nitrogen at the sintering temperature to obtain a single-phase titanium carbonitride sintered body with high purity.
[0031] Titanium carbonitride is a composite compound formed in a single TiC lattice where nitrogen atoms occupy the positions of the original carbon atoms in the lattice. x N y There are two ideal modes for the ratio of carbon and nitrogen atoms in TiC 0.5 N 0.5 (TiCN55) and TiC0.7N0.3 (TiCN73), TiCN55 powder is prepared in this embodiment and the following embodiments and comparative examples. The quality of titanium carbonitride powder products mainly depends on the oxygen content and free carbon content. The smaller the better. The total carbon content and nitrogen content should be determined according to user requirements. Generally speaking, the higher the carbon content, the higher the strength and the worse the toughness. The higher the nitrogen content, the lower the strength and the higher the toughness. The composition index of TiCN55 prepared in this embodiment is shown in Table 2, and the electron microscope image of the prepared titanium carbonitride powder is shown in Table 2. Figure 3 .
[0032] Examples 2-3 A method for preparing titanium carbonitride powder by a secondary sintering method, using the same ratio of titanium dioxide to carbon black as in Example 1, and substantially the same method as in Example 1, except that: In step (1), Examples 2 and 3 were pre-sintered at 1500°C and 1600°C, respectively, and the obtained pre-sintered materials were 173g and 174g, respectively. The results are shown in Tables 1 and Figure 1 The electron microscope image of the pre-sintered material obtained by pre-sintering in Example 2 is shown in FIG. Figure 2 .
[0033] Comparative Examples 1-3 A method for preparing titanium carbonitride powder by a secondary sintering method, using the same ratio of titanium dioxide to carbon black as in Example 1, and substantially the same method as in Example 1, except that: In step (1), Comparative Examples 1 to 3 were pre-sintered at 1100°C, 1200°C, and 1300°C, respectively. The pre-sintered materials obtained in Comparative Examples 2 and 3 were 232g and 276g, respectively. The results are shown in Tables 1 and Figure 1 .
[0034] The sintering conditions at different pre-sintering temperatures are shown in Table 1. The phase analysis of the materials at different temperatures is shown in Table 1. Figure 1 From Table 1 and Figure 1 From the results, it can be seen that the pre-sintering temperature has a great influence on the weight loss rate. The pre-sintering effect at 1100~1300℃ is not good. Pre-sintering at 1400~1600℃ can make the carbon dioxide and carbon black in the material react moderately, consume most of the oxygen and carbon elements, and most of the oxygen elements and part of the carbon elements generate carbon monoxide and are discharged. The remaining solid part is composed of carbon, titanium carbonitride, and titanium oxide, but the weight is greatly reduced, especially from 1200℃ to 1300℃ and 1300℃ to 1400℃, the weight loss rate increases greatly, and the weight loss rate is basically stable at 1400~1600℃. The weight loss rate at 1400~1600℃ is about 42%, and the volume is reduced by about 50%.
[0035] Table 1 Element content and weight loss rate of pre-sintered materials at various pre-sintering temperatures Note: / indicates not tested.
[0036] Examples 4-5 A method for preparing titanium carbonitride powder by a secondary sintering method, using the same ratio of titanium dioxide to carbon black as in Example 1, and substantially the same method as in Example 1, except that: In step (3), Examples 4 and 5 were sintered at temperatures of 1780-1820°C and 1830-1870°C, respectively, during the secondary sintering stage. The obtained sintered bodies were crushed, and the components detected were shown in Table 2.
[0037] Table 2 Effect of different secondary sintering temperatures on the composition of titanium carbonitride powder Comparative Example 4 Titanium carbonitride powder is prepared using the existing one-shot sintering process, as follows: The ratio of titanium dioxide to carbon black is exactly the same as that used in Example 1. 2.5 kg of the mixture of titanium dioxide and carbon black is charged, the sintering temperature is 1870-1900°C, the nitrogen flow rate is 4-6 L / min, and the pushing speed is 60 min / boat.
[0038] Test results: TiCN55 powder, total carbon content is 9.9~10.4%, nitrogen content is 10.7~11.0%, oxygen content is ≤0.2%, and free carbon content is ≤0.1%, which meets the index requirements.
[0039] The material weight loss results are shown in Table 6.
[0040] Table 6 Material weight loss record of existing process (one-shot sintering method) like Figure 4 As shown, it is an electron microscope image of the finished product of the 1880°C single-sintering method. Compared with the electron microscope image of the finished product of the double-sintering method in Example 1 of the present invention, neither method is ball-milled. It can be seen that the grain size and morphology of the two methods are not much different. However, the present invention adopts the double-sintering method. While being able to produce titanium carbonitride powder products of the same quality, the production capacity is greatly improved, making it easier to achieve large-scale mass production.
[0041] By applying the method of the present invention, qualified titanium carbonitride powder can be prepared, and the production capacity of a single graphite carbon tube furnace is increased by more than double.
[0042] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.
Claims
1. A method for preparing titanium carbonitride powder by a secondary sintering method, characterized in that: The method comprises the following steps: (1) Pre-sintering stage A mixture of titanium dioxide and carbon black in a mass ratio of 1:(0.3-0.4) is placed in a container and placed in a heating device. Nitrogen is passed through the container and heated at 1400-1600°C. After the center temperature of the material reaches the set temperature, the reaction is complete. After the reaction is completed, the material is cooled and taken out of the furnace to obtain a pre-burned material. (2) Pre-burning material mixing stage Mixing the pre-burned materials uniformly; (3) Secondary sintering stage The mixed pre-sintered material is added to a graphite boat, which is then placed in a carbon tube furnace and sintered with nitrogen. The sintering temperature is 1700-1900°C, and the boat pushing speed is 50-70 minutes per boat. The sintered material after being taken out of the furnace is a titanium carbonitride sintered product, which is then crushed to obtain a titanium carbonitride powder product.
2. The method for preparing titanium carbonitride powder by secondary sintering according to claim 1, characterized in that: In step (1), the nitrogen flow rate is 1.0 to 1.5 L / min per kilogram of charge; in step (2), the nitrogen flow rate is 2.0 to 3.0 L / min per kilogram of charge.
3. The method for preparing titanium carbonitride powder by secondary sintering according to claim 1, characterized in that: In step (1), the heating device in the pre-sintering stage is selected from any one of an electric furnace, a tunnel furnace, a push plate furnace, a rotary furnace and a tubular furnace.
4. The method for preparing titanium carbonitride powder by secondary sintering according to claim 1, characterized in that: In step (1), the reaction time is 1 h to 2 h.
5. The method for preparing titanium carbonitride powder by secondary sintering according to claim 1, characterized in that: In step (1), heating is performed at a temperature of 1400-1500°C.
6. The method for preparing titanium carbonitride powder by secondary sintering according to claim 1, characterized in that: In step (2), the pre-burned materials are mixed using a mixer.
7. The method for preparing titanium carbonitride powder by secondary sintering according to any one of claims 1 to 6, characterized in that: In step (3), the diameter Φ of the carbon tube furnace is 128-220 mm, and the length of the graphite boat is 300-500 mm.