Method for recycling titanium waste to prepare high-performance surface-modified titanium filter

Abstract

This invention provides a method for preparing high-performance surface-modified titanium filters from recycled titanium waste, relating to the technical field of filter preparation. The method includes sequential steps of titanium raw material hydrogenation, preparation of micron-sized hydride titanium powder, preparation of a porous titanium filter cold forming mold, preparation of a titanium filter compact, preparation of the porous titanium filter, and surface modification of the high-performance surface-modified titanium filter. The filters prepared from the titanium waste of this invention have long service life, high filtration accuracy, short production process, and low production cost; they solve the problems of short life, easy perforation, easy breakage, insufficient filtration accuracy, and high cost associated with existing filters used for filtering titanium tetrachloride. The filter preparation technology of this invention has no special restrictions on raw material composition, can meet the needs of different production environments and conditions, and has wide applicability.

Description

Technical Field

[0001] This invention relates to the technical field of filter preparation, and in particular to a method for preparing high-performance surface-modified titanium filters by recycling titanium waste. Background Technology

[0002] Titanium (Ti) and its alloys have high specific strength, good corrosion resistance, excellent high temperature resistance and biocompatibility. They are widely used not only in aerospace, defense equipment, marine engineering, chemical industry and medical equipment, but also perform well in filtration applications in extreme environments. They are considered ideal materials for high-performance filters.

[0003] Titanium tetrachloride is the basic raw material for preparing sponge titanium. However, due to the high impurity content in the enriched feedstock used for chlorination, the prepared titanium tetrachloride contains a large amount of solid impurities. These solids severely affect the stable operation of the refining system and the quality of the refined titanium tetrachloride product, thus placing higher demands on the purification efficiency of titanium tetrachloride. Previously, stainless steel and ceramic filters were used, but these suffered from short filter lifespan, easy perforation, and breakage. Therefore, factories currently typically use metallic titanium filters for purification. However, TiCl4 is corrosive, and metallic titanium filters still experience corrosion, low yield, and require further improvement in service life. Furthermore, using electrolytic titanium powder as the filter material makes metallic titanium filters very expensive, severely restricting the development of titanium tetrachloride filtration technology. Therefore, it is necessary to regulate the intrinsic properties of metallic titanium filters to improve their corrosion resistance and extend their service life.

[0004] Furthermore, sub-grade titanium refers to products produced during the sponge titanium production process that fail to meet national quality standards for sponge titanium due to their quality, morphology, and particle size. Currently, sub-grade titanium is mainly used as an additive in steelmaking, a grain refiner in aluminum processing, a raw material for smelting titanium-iron alloys, titanium casting, and titanium powder metallurgy. However, these applications do not fully realize the value of sub-grade titanium, necessitating the development of an efficient technology for recycling and utilizing sub-grade titanium to achieve high-value utilization of titanium resources.

[0005] Therefore, there is an urgent need for a low-cost, high-yield, near-net-shape preparation method that uses non-equivalent titanium, sponge titanium, or titanium waste as raw materials or additives for filters. This method would significantly reduce the manufacturing cost of titanium filter elements, improve the material properties of titanium filters through coating, and enable the recycling of titanium waste. This would meet the requirements of efficient and low-cost purification of titanium tetrachloride and high-value utilization of non-equivalent titanium.

[0006] Chinese patent CN108251789A discloses a method for in-situ preparation of TiCN coating on titanium alloy surface. The method involves mechanically cleaning the surface of the titanium alloy workpiece, applying petroleum jelly, then laser irradiating it under nitrogen atmosphere protection, and finally cleaning and drying. Although the TiCN coating prepared by this method can improve heat dissipation, wear resistance, local repair and corrosion resistance, it will block the pores if applied to porous structures.

[0007] Chinese patent CN104141063A discloses a method for preparing titanium carbide-reinforced porous titanium-based materials in situ. This method employs powder metallurgy pore-forming agent technology, using urea, carbon powder, and titanium powder through batching, mixing, pressing, and sintering steps to synthesize titanium carbide-reinforced porous titanium-based composite materials in situ. While this method enhances mechanical properties, high-temperature performance, and corrosion resistance, the use of urea as a pore-forming agent results in insufficient porosity and pore size uniformity in the prepared porous material, affecting the filtration accuracy and efficiency when used as a filter.

[0008] Chinese patent CN107287464A discloses a method for preparing a titanium-based porous composite material containing nano-TiN ceramics. This method uses powder metallurgy pore-forming agent technology. By introducing high-purity nitrogen gas at a certain pressure during the ball milling of titanium powder, a composite powder preform containing nano-TiN ceramic particles is prepared. A certain amount of anhydrous ethanol is added as a mixing agent and binder, and it is uniformly mixed with short rod-shaped urea. The mixture is then pressed into a green body, sintered under low temperature vacuum, and sintered under high temperature solid-state to prepare the titanium-based porous composite material. Not only is the preparation process complex, but the amount of nano-titanium nitride particles prepared and their distribution in the composite powder are also difficult to control effectively. The defects of urea as a pore-forming agent are not resolved, and the filtration performance of the prepared porous material is poor. Summary of the Invention

[0009] To address the shortcomings of existing titanium filters using titanium tetrachloride filtration technology, such as short service life, easy perforation, easy breakage, insufficient filtration accuracy, complex process flow, easy pore clogging, uneven pore distribution, poor high-temperature resistance and corrosion resistance, high manufacturing cost, and poor filtration efficiency, while coatings can alleviate these issues, the coating process suffers from problems such as high urea loss, poor pore opening effect, insufficient bonding between nano-TiN ceramic particles and the titanium alloy matrix, uneven distribution of nano-TiN particles, difficulty in simultaneously controlling pore size, distribution, and shape, as well as the interaction between pores and particles, the possibility of further weakening of interfacial bonding at high temperatures, or adverse chemical reactions between particles and the matrix. This invention proposes a method for preparing high-performance surface-modified titanium filters from recycled titanium waste, which solves the aforementioned problems. The technical solution is as follows:

[0010] A method for preparing a high-performance surface-modified titanium filter from recycled titanium waste, comprising the following steps:

[0011] S1. Hydrogenation of titanium raw materials: The titanium raw material blocks are hydrogenated in a hydrogenation furnace to obtain easily breakable hydrogenated titanium blocks;

[0012] S2, Preparation of micron-sized titanium hydride powder: The easily breakable titanium hydride block of S1 is placed in a ball mill jar filled with high-purity argon gas for high-energy ball milling. A pore-forming agent is added during ball milling to obtain micron-sized titanium hydride powder.

[0013] S3. Preparation of cold isothermal forming mold for porous titanium filter: A tubular or square tube soft sleeve is made of polyurethane or silicone. The soft sleeve has a stainless steel core rod in the middle. The core rod is fixed by polyurethane or silicone plugs that match the upper and lower ends of the soft sleeve. A porous stainless steel bushing is fitted on the outside of the polyurethane or silicone soft sleeve. The bushing is the same length as the soft sleeve and the bushing is larger than the soft sleeve. The soft sleeve, core rod, plug and bushing constitute the cold isothermal forming mold.

[0014] S4. Preparation of porous titanium filter compact: The micron-sized titanium hydride powder of S2 is loaded into the tubular or square tube soft sleeve of S3 and sealed. Then, the forming mold containing the powder is placed into a cold isostatic press for cold isostatic pressing, demolded and taken out to obtain a tubular or square tube porous titanium filter compact.

[0015] S5. Preparation of porous titanium filter: Place the S4 tubular or square tubular titanium filter blank into a vacuum sintering furnace, evacuate the vacuum, and heat to sinter to obtain a porous titanium filter.

[0016] S6. Surface modification of porous titanium filter: The S5 porous filter is subjected to surface modification treatment by passing nitrogen or methane gas through it to obtain a high-performance porous titanium filter with a porous coating on the surface.

[0017] Optionally, the hydrogenation temperature in S1 is 300-600℃, the holding time is 1-4h, the hydrogen content in the easily broken hydrogenated titanium block is 2-3.2wt.%, and the titanium raw material block is substandard titanium, sponge titanium or other titanium waste with no oil on the surface.

[0018] Optionally, the pore-forming agent in S2 is a salt of NaCl, KCl, or CaCl2, with an addition amount of 1-5 wt.%; the ball-to-material ratio of the high-energy ball mill is 5:1-10:1, the ball milling speed is 300-600 rpm, the grinding balls are stainless steel balls with a diameter of 6-10 mm, the ball milling time is 2-4 h, and the particle size of the micron-sized titanium hydride powder is 50-200 mesh, with an irregular block shape.

[0019] Optionally, in S3, the total length of the soft sleeve is 5-200cm, and the thickness is 5-25mm. The lower end of the soft sleeve structure is a single mold and cannot be opened, while the upper end is a split mold and can be partially opened through serrated or corrugated engagement. The length of the upper end is 1 / 2-3 / 4 of the total length of the sleeve. The stainless steel bushing has a left-right split mold structure and is fixed by hose clamps or buckles. The bushing thickness is 1-3mm. The mandrel taper is 1-3°, and the bushing diameter is 2-8mm larger than the soft sleeve diameter. The perforated stainless steel bushing has a hole diameter of 3-20mm, and the hole area is 50-80% of the outer surface area of ​​the bushing.

[0020] Optionally, the pressing pressure of the S4 cold isostatic pressing is 80-200MPa, the holding pressure is 60-240s, the wall thickness of the tubular or square tube titanium filter blank is 10-20mm, and the porosity is 30-55%.

[0021] Optionally, the vacuum sintering temperature in S5 is 950-1200℃, and the vacuum degree is 10. -2 Pa, sintering time is 1-4h.

[0022] Optionally, the high-performance porous titanium filter in S5 has a porosity of 30-60%, a pore size of 10-100μm, a hydrogen content of ≤0.03wt.%, and a compressive strength of ≥150MPa.

[0023] Optionally, the surface modification treatment temperature in S6 is 750-1000℃, and the holding time is 1-2h.

[0024] Optionally, the inner and outer walls of the high-performance porous titanium filter with a porous coating in S6 are both made of TiN or TiC porous coating, with a coating thickness of 1-3 mm, a porosity of 30-60%, a pore size of 10-100 μm, a hydrogen content of ≤0.03 wt.%, and a compressive strength of ≥200 MPa.

[0025] Technical principle of the invention:

[0026] To address the shortcomings of existing titanium tetrachloride filters, such as short service life, easy perforation, easy breakage, and insufficient filtration accuracy, as well as high production costs, this invention proposes a high-performance filter made primarily from non-titanium chloride, combined with technologies such as hydrogenation crushing, cold isostatic pressing, and vacuum sintering. This enables the high-value recycling of non-titanium chloride.

[0027] The titanium used as a raw material in this invention is not limited to incomplete titanium; sponge titanium or other titanium waste with no oil stains on the surface, such as titanium shavings and scraps, can also be used as raw materials. The raw material cost is low, the industrial applicability is strong, the process is simple, and the flow is short. It is not only suitable for titanium tetrachloride filtration but also for filtration of other industrial products, demonstrating excellent technical versatility.

[0028] The soft sleeve structure, mandrel taper design, mandrel fixing method, and stainless steel bushing structure designed in this invention were obtained through extensive experimental optimization and verification. They were also combined with the characteristics of titanium alloy powder, forming problems, demolding difficulty, filter structure, quality, and were matched with parameters such as deformation control, shrinkage rate, porosity, and coating thickness during the cold forming process of titanium alloy filters. These features could not be obtained by calculation based on conventional experimental operations.

[0029] To ensure the integrity and forming quality of the directly formed filter structure, this invention designs a soft-shell sleeve structure. The lower end is a single mold that cannot be opened, while the upper end is a split mold that can be partially opened. Through serrated or corrugated engagement, the length of the upper end is 1 / 2 to 3 / 4 of the total sleeve length. This design ensures convenient demolding of the formed filter blank, maintains the integrity of the blank structure, and prevents problems such as damage, missing corners, and cracks. The fact that the lower end cannot be opened ensures accurate mold closing, avoiding problems such as inaccurate mold positioning and poor surface quality of the blank caused by an excessively long sleeve.

[0030] This invention relates to a filter with a directly formed hollow structure. The intermediate core rod structure is designed to be fixed by plugs that match the upper and lower ends of the soft sleeve. This ensures that the core rod does not move during powder filling, resulting in uniform powder filling and consistent wall thickness of the blank. It also maintains the straightness of the filter's hollow structure. Furthermore, to facilitate demolding without damaging the internal structure of the blank, the core rod is designed with a 1-3° taper. After the blank is formed, the taper allows for direct removal of the core rod, simplifying and facilitating the process. The internal structure of the blank remains intact and free of defects. The taper angle design was obtained through extensive testing and verification; an excessively large taper angle can lead to uneven stress, preventing forming, or causing the blank to crack during pressing.

[0031] To ensure the surface quality of the filter blank, this invention employs a porous stainless steel bushing structure. The bushing has holes with a diameter of 3-20 mm, a hole area of ​​50-80% of the bushing's outer surface area, and a thickness of 1-3 mm. This design ensures the shape and structure of the soft sleeve, preventing deformation of the tall filter blank and eliminating issues such as bending and warping. It also guarantees the engagement stability of the open-end soft sleeve, avoiding defects such as unevenness at the opening. Furthermore, the porous structure does not interfere with the transmission of liquid pressure to the soft sleeve, ensuring consistent blank density. In addition, the bushing's left-right mold separation structure simplifies demolding.

[0032] This invention directly simplifies the process of preparing titanium powder from incompletely hydrogenated titanium hydride. It proposes to use incompletely hydrogenated titanium hydride as raw material to prepare porous titanium filters. During the sintering process, titanium hydride undergoes a dehydrogenation reaction, achieving integrated dehydrogenation and sintering. The hydrogen gas released at high temperature is used to create pores. After sintering, the hydrogen content is ≤0.03wt.%, which shortens the production process and reduces production costs.

[0033] The hydrogenated powder used in this invention has a particle size of 50-200 mesh, which avoids the problem that when the powder particle size is small, the relative density of the pressed blank is large and it is difficult to ensure the porosity of the filter. It also avoids the problems that when the powder particle size is large, the filter strength is low, and it is easy to have slag shedding and short service life.

[0034] In the preparation process of this invention, the hydrogen content of the titanium hydride block is ≥2wt.% and ≤3.2wt.%, which was obtained through extensive experimental verification and optimization and cannot be calculated through conventional experiments. The lower limit of 2wt.% hydrogen content ensures that the titanium hydride block can be easily broken during high-energy ball milling, while the upper limit of 3.2wt.% ensures the structural stability of the pressed blank during the pressing process, making it less prone to crushing. It also avoids problems such as excessive dehydrogenation during sintering due to excessive hydrogen content, which could damage the integrity of the filter structure and cause cracks. Furthermore, incomplete hydrogenation reduces production costs and improves production efficiency. It is worth noting that this invention directly simplifies the process of preparing incompletely hydrogenated titanium powder by proposing the use of incompletely hydrogenated titanium hydride as raw material to prepare porous titanium filters. During sintering, the titanium hydride undergoes a dehydrogenation reaction, achieving integrated dehydrogenation and sintering. The hydrogen gas released at high temperature also serves to create pores. After sintering, the hydrogen content is ≤0.03wt.%, shortening the production process and reducing production costs.

[0035] The cold isostatic pressing process of this invention ensures the yield of titanium filters. By designing claddings of different specifications and shapes, the requirements of filters for different application scenarios can be met. Using inhomogeneous titanium as raw material to prepare filters realizes the recycling of resources and further reduces production costs.

[0036] This invention utilizes nitrogen or methane gas surface treatment to generate TiC or TiN reinforced coatings in situ on the inner and outer surfaces of porous titanium filters. This process does not affect the porosity of the filter and gives the porous titanium filter the advantages of high wear resistance, high hardness, and high corrosion resistance of TiC or TiN, thus significantly extending the service life of the filter.

[0037] This invention utilizes low-cost raw materials, employs a simple and short preparation process, and boasts strong industrial applicability. Furthermore, it recycles and reuses titanium resources, achieving sustainable development of titanium resources. The filter prepared by this invention is not only applicable to titanium tetrachloride filtration but also suitable for filtration of other industrial products, especially those operating in extreme environments, demonstrating excellent technical versatility.

[0038] The above technical solution has at least the following advantages compared with the existing technology:

[0039] The above-described solution of the present invention proposes a method for preparing high-performance surface-modified titanium filters by recycling titanium waste. This method can solve the problems of existing titanium filters using titanium tetrachloride, such as short service life, insufficient filtration accuracy, complex process flow, easy pore clogging, uneven pore distribution, poor high temperature resistance and corrosion resistance, high preparation cost, poor filtration efficiency, large urea loss and poor pore opening effect, insufficient bonding between nano-TiN ceramic particles and titanium alloy matrix, uneven distribution of nano-TiN particles, difficulty in simultaneously controlling the size, distribution and shape of pores, as well as the interaction between pores and particles, and the possibility that high temperature may further weaken the interfacial bonding force or cause adverse chemical reactions between particles and matrix.

[0040] This invention uses incompletely hydrogenated titanium hydride as raw material to prepare porous titanium filters. During the sintering process, titanium hydride undergoes a dehydrogenation reaction, achieving integrated dehydrogenation and sintering. The hydrogen gas released at high temperature also serves to create pores. After sintering, the hydrogen content is ≤0.03wt.%, which shortens the production process and reduces production costs.

[0041] This invention employs mold design and fabrication, along with cold isostatic pressing (COP) technology, to achieve near-finished filters, thereby reducing manufacturing costs. In particular, by designing the specifications and shape of the COP cladding, filters tailored to different application scenarios can be manufactured.

[0042] The application of the cold isostatic pressing process in this invention effectively improves the yield of titanium filters, with a material utilization rate of ≥98%. Furthermore, using inhomogeneous titanium as a raw material further reduces production costs. The filter prepared by this invention significantly improves the purification efficiency of titanium tetrachloride, providing a more economical and efficient solution for the recycling and production of titanium resources.

[0043] In summary, compared to other traditional methods, the method of this invention uses non-equivalent titanium and other titanium waste materials with oil-free surfaces, such as titanium shavings and scraps, as raw materials. It employs processes such as hydrogenation crushing, cold forming, sintering, and surface modification to prepare a high-performance titanium filter. This filter features long service life, high filtration accuracy, short production process, and low production cost. It solves the problems of existing filters used for filtering titanium tetrachloride, such as short lifespan, easy perforation, easy breakage, insufficient filtration accuracy, and high cost. The filter preparation technology of this invention has no special restrictions on raw material composition, can meet the needs of different production environments and conditions, and has wide applicability. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a process flow diagram of a method for preparing high-performance surface-modified titanium filters from recycled titanium waste according to the present invention;

[0046] Figure 2 This is a structural diagram of the soft sleeve and bushing involved in the method of preparing high-performance surface-modified titanium filter by recycling titanium waste according to the present invention, wherein: Figure (a) is the main view of the bushing, Figure (b) is the main view of the soft sleeve, and Figure (c) is the effect diagram after the soft sleeve is opened. Detailed Implementation

[0047] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0048] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0049] In the embodiments of the present invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that when the distinction is not emphasized, their intended meanings are consistent.

[0050] In this embodiment of the invention, sometimes a subscript such as W1 may be written in a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0051] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0052] A method for preparing a high-performance surface-modified titanium filter from recycled titanium waste, comprising the following steps:

[0053] S1. Hydrogenation of titanium raw materials: The titanium raw material blocks are hydrogenated in a hydrogenation furnace to obtain easily breakable hydrogenated titanium blocks;

[0054] S2, Preparation of micron-sized titanium hydride powder: The easily breakable titanium hydride block of S1 is placed in a ball mill jar filled with high-purity argon gas for high-energy ball milling. A pore-forming agent is added during ball milling to obtain micron-sized titanium hydride powder.

[0055] S3. Preparation of cold isothermal forming mold for porous titanium filter: A tubular or square tube soft sleeve is made of polyurethane or silicone. The soft sleeve has a stainless steel core rod in the middle. The core rod is fixed by polyurethane or silicone plugs that match the upper and lower ends of the soft sleeve. A porous stainless steel bushing is fitted on the outside of the polyurethane or silicone soft sleeve. The bushing is the same length as the soft sleeve and the bushing is larger than the soft sleeve. The soft sleeve, core rod, plug and bushing constitute the cold isothermal forming mold.

[0056] S4. Preparation of porous titanium filter compact: The micron-sized titanium hydride powder of S2 is loaded into the tubular or square tube soft sleeve of S3 and sealed. Then, the forming mold containing the powder is placed into a cold isostatic press for cold isostatic pressing, demolded and taken out to obtain a tubular or square tube porous titanium filter compact.

[0057] S5. Preparation of porous titanium filter: Place the S4 tubular or square tubular titanium filter blank into a vacuum sintering furnace, evacuate the vacuum, and heat to sinter to obtain a porous titanium filter.

[0058] S6. Surface modification of porous titanium filter: The S5 porous filter is subjected to surface modification treatment by passing nitrogen or methane gas through it to obtain a high-performance porous titanium filter with a porous coating on the surface.

[0059] Specifically, the hydrogenation treatment temperature in S1 is 300-600℃, the holding time is 1-4h, the hydrogen content in the easily broken hydrogenated titanium blocks is 2-3.2wt.%, and the titanium raw material blocks are non-equivalent titanium, sponge titanium or other titanium waste with no oil stains on the surface.

[0060] Specifically, the pore-forming agent in S2 is a salt of NaCl, KCl, or CaCl2, with an addition amount of 1-5 wt.%; the ball-to-material ratio of the high-energy ball mill is 5:1-10:1, the ball milling speed is 300-600 rpm, the grinding balls are stainless steel balls with a diameter of 6-10 mm, the ball milling time is 2-4 h, and the micron-sized titanium hydride powder has a particle size of 50-200 mesh and an irregular block shape.

[0061] Specifically, in S3, the total length of the soft sleeve is 5-200cm, and the thickness is 5-25mm. The lower end of the soft sleeve structure is a single mold and cannot be opened, while the upper end is a split mold and can be partially opened through serrated or corrugated engagement. The length of the upper end is 1 / 2-3 / 4 of the total length of the sleeve. The stainless steel bushing has a left-right split mold structure and is fixed by hose clamps or buckles. The bushing thickness is 1-3mm. The mandrel taper is 1-3°, and the bushing diameter is 2-8mm larger than the soft sleeve diameter. The perforated stainless steel bushing has a hole diameter of 3-20mm, and the hole area is 50-80% of the outer surface area of ​​the bushing.

[0062] Specifically, the pressing pressure of S4 cold isostatic pressing is 80-200MPa, the holding pressure is 60-240s, the wall thickness of the tubular or square tube titanium filter blank is 10-20mm, and the porosity is 30-55%.

[0063] Specifically, the vacuum sintering temperature in S5 is 950-1200℃, and the vacuum degree is 10. -2 Pa, sintering time is 1-4h.

[0064] Specifically, the high-performance porous titanium filter in S5 has a porosity of 30-60%, a pore size of 10-100μm, a hydrogen content of ≤0.03wt.%, and a compressive strength of ≥150MPa.

[0065] Specifically, the surface modification treatment temperature in S6 is 750-1000℃, and the holding time is 1-2h.

[0066] Specifically, the inner and outer walls of the high-performance porous titanium filter with a porous coating in S6 are both made of TiN or TiC porous coating, with a coating thickness of 1-3 mm, a porosity of 30-60%, a pore size of 10-100 μm, a hydrogen content of ≤0.03 wt.%, and a compressive strength of ≥200 MPa.

[0067] Example 1

[0068] A method for preparing a high-performance surface-modified titanium filter from recycled titanium waste, comprising the following steps:

[0069] S1. Hydrogenation of titanium raw materials: 200 kg of titanium blocks of different grades are hydrogenated in a hydrogenation furnace at a temperature of 300℃. Hydrogen gas is introduced and the holding time is 2 hours. The hydrogen content in the easily broken hydrogenated titanium blocks is 2.9 wt.%, thus obtaining easily broken hydrogenated titanium blocks.

[0070] S2. Preparation of micron-sized titanium hydride powder: The easily breakable titanium hydride blocks from S1 were placed in a ball mill jar filled with high-purity argon gas for high-energy ball milling. The ball-to-material ratio for high-energy ball milling was 5:1, the milling speed was 300 rpm, the grinding balls were stainless steel balls with a size of 6 mm, and the milling time was 2 hours. During ball milling, 2 wt.% NaCl pore-forming agent was added to obtain micron-sized titanium hydride powder. The particle size of the micron-sized titanium hydride powder was 100 mesh, and the shape was irregular blocky.

[0071] S3. Preparation of cold isothermal forming mold for porous titanium filter: A tubular soft sleeve is made of polyurethane, with a stainless steel core rod in the middle of the soft sleeve. The core rod is fixed by polyurethane plugs that match the upper and lower ends of the soft sleeve. A porous stainless steel bushing is fitted on the outside of the polyurethane soft sleeve. The bushing is the same length as the soft sleeve and the bushing is larger than the soft sleeve. The cold isothermal forming mold is composed of the soft sleeve, core rod, plug and bushing.

[0072] The soft sleeve has a total length of 80cm, an inner diameter of 80mm, and a thickness of 10mm. The lower end of the soft sleeve is a single mold and cannot be opened, while the upper end is a split mold and can be partially opened through serrated or corrugated engagement. The length of the upper end is 5 / 8 of the total length of the sleeve. The stainless steel bushing has a left-right split mold structure and is fixed by hose clamps or buckles. The mandrel has a diameter of 58mm and a taper of 2°. The bushing is 80cm long, has a diameter of 102mm, and a bushing hole diameter of 5mm, with the hole area accounting for 60% of the total bushing area.

[0073] S4. Preparation of Titanium Filter Preform: Micron-sized alloy powder (S2) is loaded into the tubular soft sleeve (S3) and sealed. Then, the forming mold containing the powder is placed in a cold isostatic press for cold isostatic pressing at a pressure of 150 MPa for 180 seconds. The preform is then demolded to obtain a porous tubular titanium filter preform. The porous tubular titanium filter preform has a wall thickness of 10 mm and a porosity of 40%.

[0074] S5. Preparation of porous titanium filter: The S4 tubular titanium filter blank is placed in a vacuum sintering furnace, and after vacuuming, it is heated for sintering. The vacuum sintering temperature is 1100℃ and the vacuum degree is 10. -2 Pa, sintering time of 2h, to obtain a porous titanium filter;

[0075] The porous filter has a porosity of 40%, a pore size of 100 μm, a hydrogen content of 0.01 wt.%, and a compressive strength of 150 MPa.

[0076] S6. Surface modification of porous titanium filter: The S5 porous filter is subjected to surface modification treatment by passing nitrogen gas through it. The surface modification treatment temperature is 800℃, the holding time is 1h, the TiN coating thickness is 1mm, and after cooling, a high-performance porous titanium filter with a porous coating on the surface is obtained.

[0077] The high-performance porous titanium filter with a porous coating on its surface prepared in this embodiment has a porosity of 40%, a pore size of 100 μm, a hydrogen content of ≤0.01 wt.%, and a compressive strength of 200 MPa.

[0078] Example 2

[0079] A method for preparing a high-performance surface-modified titanium filter from recycled titanium waste, comprising the following steps:

[0080] S1. Hydrogenation of titanium raw materials: 300 kg of titanium shavings with no oil stains on the surface were hydrogenated in a hydrogenation furnace at a temperature of 350℃. Hydrogen gas was introduced and the holding time was 1 hour. The hydrogen content in the easily broken hydrogenated titanium blocks was 3.1 wt.%, and easily broken hydrogenated titanium blocks were obtained.

[0081] S2. Preparation of micron-sized titanium hydride powder: The easily breakable titanium hydride blocks from S1 were placed in a ball mill jar filled with high-purity argon gas for high-energy ball milling. The ball-to-material ratio for high-energy ball milling was 8:1, the milling speed was 300 rpm, the grinding balls were stainless steel balls with a size of 6 mm, and the milling time was 1 hour. During ball milling, 1 wt.% NaCl pore-forming agent was added to obtain micron-sized titanium hydride powder. The particle size of the micron-sized titanium hydride powder was 150 mesh, and the shape was irregular blocky.

[0082] S3. Preparation of cold isothermal forming mold for porous titanium filter: A tubular soft sleeve is made of silicone, with a stainless steel core rod in the middle of the soft sleeve. The core rod is fixed by silicone plugs that match the upper and lower ends of the soft sleeve. A porous stainless steel bushing is fitted to the outside of the silicone soft sleeve. The bushing is the same length as the soft sleeve and the bushing is larger than the diameter of the soft sleeve. The cold isothermal forming mold is composed of the soft sleeve, core rod, plug and bushing.

[0083] The soft sleeve has a total length of 150cm, an inner diameter of 70mm, and a thickness of 15mm. The lower end of the soft sleeve is a single mold and cannot be opened, while the upper end is a split mold and can be partially opened through serrated or corrugated engagement. The length of the upper end is 5 / 8 of the total length of the sleeve. The stainless steel bushing has a left-right split mold structure and is fixed by hose clamps or buckles. The mandrel has a diameter of 38mm and a taper of 1°. The bushing is 150cm long, has a diameter of 102mm, and a bushing hole diameter of 10mm, with the hole area accounting for 80% of the total bushing area.

[0084] S4. Preparation of Titanium Filter Preform: S2 micron-sized alloy powder is loaded into the tubular soft sleeve in S3 and sealed. Then, the forming mold containing the powder is placed in a cold isostatic press for cold isostatic pressing at a pressure of 200 MPa for 200 seconds. The preform is then demolded to obtain a porous tubular titanium filter preform. The porous tubular titanium filter preform has a wall thickness of 15 mm and a porosity of 35%.

[0085] S5. Preparation of porous titanium filter: The S4 tubular titanium filter blank is placed in a vacuum sintering furnace, and after vacuuming, it is heated for sintering. The vacuum sintering temperature is 1150℃ and the vacuum degree is 10. -2 Pa, sintering time of 1 h, to obtain a porous titanium filter;

[0086] The porous filter has a porosity of 31%, a pore size of 80 μm, a hydrogen content of 0.01 wt.%, and a compressive strength of 160 MPa.

[0087] S6. Surface modification of porous titanium filter: Methane gas is introduced into the S5 porous filter for surface modification treatment. The surface modification treatment temperature is 850℃, the holding time is 1h, the TiC coating thickness is 1mm, and after cooling, a high-performance porous titanium filter with a porous coating on the surface is obtained.

[0088] The high-performance porous titanium filter with a porous coating on its surface prepared in this embodiment has a porosity of 31%, a pore size of 80 μm, a hydrogen content of 0.01 wt.%, and a compressive strength of 220 MPa.

[0089] Example 3

[0090] A method for preparing a high-performance surface-modified titanium filter from recycled titanium waste, comprising the following steps:

[0091] S1. Hydrogenation of titanium raw materials: 100 kg of sponge titanium blocks were hydrogenated in a hydrogenation furnace at a temperature of 320°C. Hydrogen gas was introduced and the holding time was 2 hours. The hydrogen content in the easily broken hydrogenated titanium blocks was 2.7 wt.%, thus obtaining easily broken hydrogenated titanium blocks.

[0092] S2. Preparation of micron-sized titanium hydride powder: The easily breakable titanium hydride blocks from S1 were placed in a ball mill jar filled with high-purity argon gas for high-energy ball milling. The ball-to-material ratio for high-energy ball milling was 10:1, the milling speed was 400 rpm, the grinding balls were stainless steel balls with a size of 8 mm, and the milling time was 2 hours. During ball milling, 1 wt.% NaCl pore-forming agent was added to obtain micron-sized titanium hydride powder. The particle size of the micron-sized titanium hydride powder was 200 mesh, and the shape was irregular blocky.

[0093] S3. Preparation of cold isothermal forming mold for porous titanium filter: A square tubular soft sleeve is made of polyurethane, with a stainless steel core rod in the middle of the soft sleeve. The core rod is fixed by polyurethane plugs that match the upper and lower ends of the soft sleeve. A porous stainless steel bushing is fitted on the outside of the polyurethane soft sleeve. The bushing is the same length as the soft sleeve and the bushing diameter is larger than the soft sleeve diameter. The cold isothermal forming mold is composed of the soft sleeve, core rod, plug and bushing.

[0094] The soft sleeve has a total length of 50cm, an inner side length of 60mm, and a thickness of 10mm. The lower end of the soft sleeve is a single mold and cannot be opened, while the upper end is a split mold and can be partially opened through serrated or corrugated engagement. The length of the upper end is 5 / 8 of the total length of the sleeve. The stainless steel bushing has a left-right split mold structure and is fixed by hose clamps or buckles. The mandrel has a side length of 39mm, a taper of 3°, a bushing length of 50cm, a bushing diameter of 82mm, a bushing hole diameter of 15mm, and a hole area of ​​60% of the total bushing area.

[0095] S4. Preparation of Titanium Filter Preform: S2 micron-sized alloy powder is loaded into the square tubular soft sleeve from S3 and sealed. Then, the forming mold containing the powder is placed in a cold isostatic press for cold isostatic pressing at a pressure of 100 MPa for 150 seconds. The preform is then demolded to obtain a porous square tubular titanium filter preform. The wall thickness of the porous square tubular titanium filter preform is 10 mm, and the porosity is 37%.

[0096] S5. Preparation of porous titanium filter: The S4 square tubular titanium filter blank is placed in a vacuum sintering furnace, and then heated for sintering after vacuuming. The vacuum sintering temperature is 1200℃ and the vacuum degree is 10. -2 Pa, sintering time of 2h, to obtain a porous titanium filter;

[0097] The porous filter has a porosity of 35%, a pore size of 90 μm, a hydrogen content of 0.01 wt.%, and a compressive strength of 170 MPa.

[0098] S6. Surface modification of porous titanium filter: Methane gas is introduced into the S5 porous filter for surface modification treatment. The surface modification treatment temperature is 900℃, the holding time is 2h, the TiC coating thickness is 1mm, and after cooling, a high-performance porous titanium filter with a porous coating on the surface is obtained.

[0099] The high-performance porous titanium filter with a porous coating on its surface prepared in this embodiment has a porosity of 35%, a pore size of 90 μm, a hydrogen content of 0.01 wt.%, and a compressive strength of 220 MPa.

[0100] Example 4

[0101] A method for preparing a high-performance surface-modified titanium filter from recycled titanium waste, comprising the following steps:

[0102] S1. Hydrogenation of titanium raw materials: 50 kg of titanium blocks of different grades are hydrogenated in a hydrogenation furnace at a temperature of 350℃. Hydrogen gas is introduced and the holding time is 2 hours. The hydrogen content in the easily broken hydrogenated titanium blocks is 3.2 wt.%, thus obtaining easily broken hydrogenated titanium blocks.

[0103] S2. Preparation of micron-sized titanium hydride powder: The easily breakable titanium hydride blocks from S1 were placed in a ball mill jar filled with high-purity argon gas for high-energy ball milling. The ball-to-material ratio for high-energy ball milling was 5:1, the milling speed was 400 rpm, the grinding balls were stainless steel balls with a size of 8 mm, and the milling time was 2 hours. During ball milling, 5 wt.% NaCl pore-forming agent was added to obtain micron-sized titanium hydride powder. The particle size of the micron-sized titanium hydride powder was 150 mesh, and the shape was irregular blocky.

[0104] S3. Preparation of cold isothermal forming mold for porous titanium filter: A tubular soft sleeve is made of polyurethane, with a stainless steel core rod in the middle of the soft sleeve. The core rod is fixed by polyurethane plugs that match the upper and lower ends of the soft sleeve. A porous stainless steel bushing is fitted on the outside of the polyurethane soft sleeve. The bushing is the same length as the soft sleeve and the bushing is larger than the soft sleeve. The cold isothermal forming mold is composed of the soft sleeve, core rod, plug and bushing.

[0105] The soft sleeve has a total length of 100cm, an inner diameter of 60mm, and a thickness of 10mm. The lower end of the soft sleeve is a single mold and cannot be opened, while the upper end is a split mold and can be partially opened through serrated or corrugated engagement. The length of the upper end is 5 / 8 of the total length of the sleeve. The stainless steel bushing has a left-right split mold structure and is fixed by hose clamps or buckles. The mandrel has a diameter of 38mm and a taper of 1°. The bushing is 1000cm long, has a diameter of 82mm, and a bushing hole diameter of 3mm, with the hole area accounting for 60% of the total bushing area.

[0106] S4. Preparation of Titanium Filter Preform: Micron-sized alloy powder (S2) is loaded into a tubular soft sleeve (S3) and sealed. The powder-filled mold is then placed in a cold isostatic press for cold isostatic pressing at a pressure of 140 MPa for 120 seconds. The preform is then demolded to obtain a porous tubular titanium filter preform. The wall thickness of the porous tubular titanium filter preform is 10 mm, and the porosity is 39%.

[0107] S5. Preparation of porous titanium filter: The S4 tubular titanium filter blank is placed in a vacuum sintering furnace, and after vacuuming, it is heated for sintering. The vacuum sintering temperature is 950℃ and the vacuum degree is 10. -2 Pa, sintering time of 2h, to obtain a porous titanium filter;

[0108] The porous filter has a porosity of 37%, a pore size of 70 μm, a hydrogen content of 0.01 wt.%, and a compressive strength of 190 MPa.

[0109] S6. Surface modification of porous titanium filter: The S5 porous filter is subjected to surface modification treatment by passing nitrogen gas through it. The surface modification treatment temperature is 850℃, the holding time is 2h, the TiN coating thickness is 2mm, and after cooling, a high-performance porous titanium filter with a porous coating on the surface is obtained.

[0110] The high-performance porous titanium filter with a porous coating on its surface prepared in this embodiment has a porosity of 37%, a pore size of 70 μm, a hydrogen content of 0.01 wt.%, and a compressive strength of 280 MPa.

[0111] Example 5

[0112] A method for preparing a high-performance surface-modified titanium filter from recycled titanium waste, comprising the following steps:

[0113] S1. Hydrogenation of titanium raw materials: 80 kg of titanium shavings with no oil stains on the surface were hydrogenated in a hydrogenation furnace at a temperature of 320℃. Hydrogen gas was introduced and the holding time was 2 hours. The hydrogen content in the easily broken hydrogenated titanium blocks was 3 wt.%, and easily broken hydrogenated titanium blocks were obtained.

[0114] S2. Preparation of micron-sized titanium hydride powder: The easily breakable titanium hydride blocks from S1 were placed in a ball mill jar filled with high-purity argon gas for high-energy ball milling. The ball-to-material ratio for high-energy ball milling was 5:1, the milling speed was 400 rpm, the grinding balls were stainless steel balls with a size of 10 mm, and the milling time was 2 hours. During ball milling, 5 wt.% KCl pore-forming agent was added to obtain micron-sized titanium hydride powder. The particle size of the micron-sized titanium hydride powder was 200 mesh, and the shape was irregular blocky.

[0115] S3. Preparation of cold isothermal forming mold for porous titanium filter: A tubular soft sleeve is made of polyurethane, with a stainless steel core rod in the middle of the soft sleeve. The core rod is fixed by polyurethane plugs that match the upper and lower ends of the soft sleeve. A porous stainless steel bushing is fitted on the outside of the polyurethane soft sleeve. The bushing is the same length as the soft sleeve and the bushing is larger than the soft sleeve. The cold isothermal forming mold is composed of the soft sleeve, core rod, plug and bushing.

[0116] The soft sleeve has a total length of 90cm, an inner diameter of 120mm, and a thickness of 15mm. The lower end of the soft sleeve is a single mold and cannot be opened, while the upper end is a split mold and can be partially opened through serrated or corrugated engagement. The length of the upper end is 1 / 2 of the total length of the sleeve. The stainless steel bushing has a left-right split mold structure and is fixed by hose clamps or buckles. The mandrel has a diameter of 88mm and a taper of 2°. The bushing is 90cm long, has a diameter of 152mm, and a bushing hole diameter of 5mm, with the hole area being 50% of the total bushing area.

[0117] S4. Preparation of Titanium Filter Preform: Micron-sized alloy powder (S2) is loaded into the tubular soft sleeve (S3) and sealed. Then, the forming mold containing the powder is placed in a cold isostatic press for cold isostatic pressing at a pressure of 120 MPa for 120 seconds. The preform is then demolded to obtain a porous tubular titanium filter preform. The wall thickness of the porous tubular titanium filter preform is 15 mm, and the porosity is 36%.

[0118] S5. Preparation of porous titanium filter: The S4 tubular titanium filter blank is placed in a vacuum sintering furnace, and after vacuuming, it is heated for sintering. The vacuum sintering temperature is 1100℃ and the vacuum degree is 10. -2 Pa, sintering time of 2h, to obtain a porous titanium filter;

[0119] The porous filter has a porosity of 34%, a pore size of 60 μm, a hydrogen content of 0.01 wt.%, and a compressive strength of 180 MPa.

[0120] S6. Surface modification of porous titanium filter: Methane gas is introduced into the S5 porous filter for surface modification treatment. The surface modification treatment temperature is 900℃, the holding time is 1h, the TiC coating thickness is 2mm, and after cooling, a high-performance porous titanium filter with a porous coating on the surface is obtained.

[0121] The high-performance porous titanium filter with a porous coating on its surface prepared in this embodiment has a porosity of 34%, a pore size of 60 μm, a hydrogen content of 0.01 wt.%, and a compressive strength of 280 MPa.

[0122] Example 6

[0123] A method for preparing a high-performance surface-modified titanium filter from recycled titanium waste, comprising the following steps:

[0124] S1. Hydrogenation of titanium raw materials: 120 kg of sponge titanium blocks were hydrogenated in a hydrogenation furnace at a temperature of 350°C. Hydrogen gas was introduced and the holding time was 2 hours. The hydrogen content in the easily broken hydrogenated titanium blocks was 3.1 wt.%, thus obtaining easily broken hydrogenated titanium blocks.

[0125] S2. Preparation of micron-sized titanium hydride powder: The easily breakable titanium hydride blocks from S1 were placed in a ball mill jar filled with high-purity argon gas for high-energy ball milling. The ball-to-material ratio for high-energy ball milling was 10:1, the milling speed was 500 rpm, the grinding balls were stainless steel balls with a size of 10 mm, and the milling time was 2 hours. During the milling process, 1 wt.% of CaCl2 pore-forming agent was added to obtain micron-sized titanium hydride powder. The particle size of the micron-sized titanium hydride powder was 200 mesh, and the shape was irregular blocky.

[0126] S3. Preparation of cold isothermal forming mold for porous titanium filter: A square tubular soft sleeve is made of polyurethane, with a stainless steel core rod in the middle of the soft sleeve. The core rod is fixed by polyurethane plugs that match the upper and lower ends of the soft sleeve. A porous stainless steel bushing is fitted on the outside of the polyurethane soft sleeve. The bushing is the same length as the soft sleeve and the bushing diameter is larger than the soft sleeve diameter. The cold isothermal forming mold is composed of the soft sleeve, core rod, plug and bushing.

[0127] The soft sleeve has a total length of 200cm, an inner side length of 100mm, and a thickness of 15mm. The lower end of the soft sleeve is a single mold and cannot be opened, while the upper end is a split mold and can be partially opened through serrated or corrugated engagement. The length of the upper end is 1 / 4 of the total length of the sleeve. The stainless steel bushing has a left-right split mold structure and is fixed by hose clamps or buckles. The mandrel has a side length of 68mm, a taper of 3°, a bushing length of 200cm, a bushing diameter of 136mm, a bushing hole diameter of 15mm, and a hole area of ​​70% of the total bushing area.

[0128] S4. Preparation of Titanium Filter Preform: S2 micron-sized alloy powder is loaded into the square tubular soft sleeve from S3 and sealed. Then, the forming mold containing the powder is placed in a cold isostatic press for cold isostatic pressing at a pressure of 120 MPa for 150 seconds. The preform is then demolded to obtain a porous square tubular titanium filter preform. The wall thickness of the porous square tubular titanium filter preform is 15 mm, and the porosity is 34%.

[0129] S5. Preparation of porous titanium filter: The S4 square tubular titanium filter blank is placed in a vacuum sintering furnace, and then heated for sintering after vacuuming. The vacuum sintering temperature is 1200℃ and the vacuum degree is 10. -2 Pa, sintering time of 2h, to obtain a porous titanium filter;

[0130] The porous filter has a porosity of 30%, a pore size of 40 μm, a hydrogen content of 0.01 wt.%, and a compressive strength of 180 MPa.

[0131] S6. Surface modification of porous titanium filter: Methane gas is introduced into the S5 porous filter for surface modification treatment. The surface modification treatment temperature is 900℃, the holding time is 2h, the TiC coating thickness is 2mm, and after cooling, a high-performance porous titanium filter with a porous coating on the surface is obtained.

[0132] The high-performance porous titanium filter with a porous coating on its surface prepared in this embodiment has a porosity of 30%, a pore size of 40 μm, a hydrogen content of 0.01 wt.%, and a compressive strength of 290 MPa.

[0133] The above-described solution of the present invention proposes a method for preparing high-performance surface-modified titanium filters by recycling titanium waste. This method can solve the problems of existing titanium filters using titanium tetrachloride, such as short service life, insufficient filtration accuracy, complex process flow, easy pore clogging, uneven pore distribution, poor high temperature resistance and corrosion resistance, high preparation cost, poor filtration efficiency, large urea loss and poor pore opening effect, insufficient bonding between nano-TiN ceramic particles and titanium alloy matrix, uneven distribution of nano-TiN particles, difficulty in simultaneously controlling the size, distribution and shape of pores, as well as the interaction between pores and particles, and the possibility that high temperature may further weaken the interfacial bonding force or cause adverse chemical reactions between particles and matrix.

[0134] This invention uses incompletely hydrogenated titanium hydride as raw material to prepare porous titanium filters. During the sintering process, titanium hydride undergoes a dehydrogenation reaction, achieving integrated dehydrogenation and sintering. The hydrogen gas released at high temperature also serves to create pores. After sintering, the hydrogen content is ≤0.03wt.%, which shortens the production process and reduces production costs.

[0135] This invention employs mold design and fabrication, along with cold isostatic pressing (COP) technology, to achieve near-finished filters, thereby reducing manufacturing costs. In particular, by designing the specifications and shape of the COP cladding, filters tailored to different application scenarios can be manufactured.

[0136] The hydrogenated powder used in this invention has a particle size of 50-200 mesh, which avoids the problem that when the powder particle size is small, the relative density of the pressed blank is large and it is difficult to ensure the porosity of the filter. It also avoids the problems that when the powder particle size is large, the filter strength is low, and it is easy to have slag shedding and short service life.

[0137] This invention generates a TiC or TiN reinforced coating in situ on the inner and outer surfaces of a porous titanium filter through nitrogen or methane gas surface modification treatment. This does not affect the porosity of the filter, and at the same time enables the porous titanium filter to have the advantages of TiC or TiN such as high wear resistance, high hardness, and high corrosion resistance, which greatly improves the service life of the filter.

[0138] The application of the cold isostatic pressing process in this invention effectively improves the yield of titanium filters, with a material utilization rate of ≥98%. Furthermore, using inhomogeneous titanium as a raw material further reduces production costs. The filter prepared by this invention significantly improves the purification efficiency of titanium tetrachloride, providing a more economical and efficient solution for the recycling and production of titanium resources.

[0139] In summary, compared to other traditional methods, the method of this invention uses non-equivalent titanium and other titanium waste materials with oil-free surfaces, such as titanium shavings and scraps, as raw materials. It employs processes such as hydrogenation crushing, cold forming, sintering, and surface modification to prepare a high-performance titanium filter. This filter features long service life, high filtration accuracy, short production process, and low production cost. It solves the problems of existing filters used for filtering titanium tetrachloride, such as short lifespan, easy perforation, easy breakage, insufficient filtration accuracy, and high cost. The filter preparation technology of this invention has no special restrictions on raw material composition, can meet the needs of different production environments and conditions, and has wide applicability.

[0140] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0141] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be a single item or multiple items.

[0142] It should be understood that, in various embodiments of the present invention, the order of the above-mentioned process numbers does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0143] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing high-performance surface-modified titanium filters from recycled titanium waste, characterized in that, The method for preparing high-performance surface-modified titanium filters by recycling titanium waste includes the following steps: S1. Hydrogenation of titanium raw materials: The titanium raw material blocks are hydrogenated in a hydrogenation furnace to obtain easily breakable hydrogenated titanium blocks. S2, Preparation of micron-sized titanium hydride powder: The easily breakable titanium hydride block of S1 is placed in a ball mill jar filled with high-purity argon gas for high-energy ball milling. A pore-forming agent is added during ball milling to obtain micron-sized titanium hydride powder. S3. Preparation of cold isothermal forming mold for porous titanium filter: A tubular or square tube soft sleeve is made of polyurethane or silicone. The soft sleeve has a stainless steel core rod in the middle. The core rod is fixed by polyurethane or silicone plugs that match the upper and lower ends of the soft sleeve. A porous stainless steel bushing is fitted on the outside of the polyurethane or silicone soft sleeve. The bushing is the same length as the soft sleeve and the bushing is larger than the soft sleeve. The soft sleeve, core rod, plug and bushing constitute the cold isothermal forming mold. The soft sleeve has a total length of 5-200cm and a thickness of 5-25mm. The lower end of the soft sleeve is a single mold and cannot be opened, while the upper end is a split mold and can be partially opened through serrated or corrugated engagement. The length of the upper end is 1 / 2-3 / 4 of the total length of the sleeve. The stainless steel bushing has a left-right split mold structure and is fixed by hose clamps or buckles. The bushing thickness is 1-3mm. The mandrel taper is 1-3°, and the bushing diameter is 2-8mm larger than the soft sleeve diameter. The perforated stainless steel bushing has a hole diameter of 3-20mm, and the hole area is 50-80% of the outer surface area of ​​the bushing. S4. Preparation of porous titanium filter compact: The micron-sized titanium hydride powder of S2 is loaded into the tubular or square tube soft sleeve of S3 and sealed. Then, the forming mold containing the powder is placed into a cold isostatic press for cold isostatic pressing, demolded and taken out to obtain a tubular or square tube porous titanium filter compact. S5. Preparation of porous titanium filter: Place the S4 tubular or square tubular titanium filter blank into a vacuum sintering furnace, evacuate the vacuum, and heat to sinter to obtain a porous titanium filter. S6. Surface modification of porous titanium filter: The S5 porous filter is subjected to surface modification treatment by passing nitrogen or methane gas through it to obtain a high-performance porous titanium filter with a porous coating on the surface.

2. The method for preparing high-performance surface-modified titanium filters from recycled titanium waste according to claim 1, characterized in that, The hydrogenation treatment temperature in S1 is 300-600℃, and the holding time is 1-4h. The hydrogen content in the easily broken hydrogenated titanium blocks is 2-3.2wt.%. The titanium raw material blocks are non-equivalent titanium, sponge titanium or other titanium waste with no oil stains on the surface.

3. The method for preparing high-performance surface-modified titanium filters from recycled titanium waste according to claim 1, characterized in that, In S2, the pore-forming agent is a salt of NaCl, KCl, or CaCl2, with an addition amount of 1-5 wt.%; the ball-to-material ratio of the high-energy ball mill is 5:1-10:1, the ball milling speed is 300-600 rpm, the grinding balls are stainless steel balls with a diameter of 6-10 mm, the ball milling time is 2-4 h, and the particle size of the micron-sized titanium hydride powder is 50-200 mesh, with an irregular block shape.

4. The method for preparing high-performance surface-modified titanium filters from recycled titanium waste according to claim 1, characterized in that, The pressing pressure of S4 cold isostatic pressing is 80-200MPa, the holding pressure is 60-240s, the wall thickness of the tubular or square tube titanium filter blank is 10-20mm, and the porosity is 30-55%.

5. The method for preparing high-performance surface-modified titanium filters from recycled titanium waste according to claim 1, characterized in that, The vacuum sintering temperature in S5 is 950-1200℃, and the vacuum degree is 10. -2 Pa, sintering time is 1-4h.

6. The method for preparing high-performance surface-modified titanium filters from recycled titanium waste according to claim 1, characterized in that, The high-performance porous titanium filter in S5 has a porosity of 30-60%, a pore size of 10-100μm, a hydrogen content of ≤0.03wt.%, and a compressive strength of ≥150MPa.

7. The method for preparing high-performance surface-modified titanium filters from recycled titanium waste according to claim 1, characterized in that, The surface modification treatment temperature in S6 is 750-1000℃, and the holding time is 1-2h.

8. The method for preparing high-performance surface-modified titanium filters from recycled titanium waste according to claim 1, characterized in that, The S6 high-performance porous titanium filter has a porous coating on both its inner and outer walls. The coating is made of TiN or TiC with a thickness of 1-3 mm, a porosity of 30-60%, a pore size of 10-100 μm, a hydrogen content of ≤0.03 wt.%, and a compressive strength of ≥200 MPa.

Images