Preparation method of large-size high-stability zirconium hydride
By combining powder metallurgy technology with ball milling, cold isostatic pressing and sintering processes, the instability problem of zirconium hydride bulk materials was solved, and large-size, highly stable zirconium hydride bulk materials were prepared, realizing the stability and large-scale production of the material.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-18
- Publication Date
- 2026-04-07
AI Technical Summary
Existing technologies for preparing large-size zirconium hydride bulk materials suffer from problems such as hydrogen-induced cracking, slow hydrogenation rate, high cost, and difficulty in controlling the stoichiometric ratio of hydrogen to zirconium. In particular, uneven hydrogen permeation in bulk zirconium materials leads to material instability.
Zirconium hydride bulk materials were prepared using powder metallurgy technology through ball milling, cold isostatic pressing and sintering processes. A binder was used to enhance mechanical strength and a zirconia film was formed on the surface to improve thermal stability.
Large-size, highly stable zirconium hydride bulk materials were successfully prepared, avoiding hydrogen-induced cracking and high-temperature hydrogen loss. The stoichiometric ratio of hydrogen to zirconium was stable, and the preparation cycle was short, making it suitable for large-scale production.
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Figure CN121800534A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of powder metallurgy, and particularly relates to a preparation method of large-size high-stability zirconium hydride. BACKGROUND
[0002] In advanced nuclear reactors, such as small modular reactors (SMR) and space reactors, due to the compact size, the shielding material of the reactor has higher requirements. As a high-efficiency, long-lasting and reliable space power supply, the advanced nuclear reactor has the advantages of light weight, small volume, high power, strong anti-radiation ability and long service life, and is the optimal choice for future space limited high-power power supply. The moderator is one of the most important core components of the advanced nuclear reactor. In order to support the compact design, hydrogen-rich materials become the preferred choice for the design of the shielding material of the advanced nuclear reactor. Zirconium hydride is a new type of neutron moderator material. Since ZrH2 has a small specific gravity, a high hydrogen content, a strong neutron moderation ability and a good thermal conductivity, it becomes the first choice of moderator material in the design of the advanced nuclear reactor.
[0003] The preparation process of the zirconium hydride neutron moderator material is mostly to process pure zirconium into a required shape and size, and place it in a hydrogenation furnace to prepare ZrH2 block material through high-temperature and normal-pressure hydrogenation. However, this process mainly has three problems in the actual preparation process: first, hydrogen-induced cracks and high-temperature hydrogen loss. In the hydrogenation process, the small atomic radius of hydrogen atoms entering the zirconium block with a large atomic radius will cause serious lattice distortion and volume expansion, resulting in the breakage of the zirconium hydride block material; second, the conventional block hydrogenation method is to prepare the zirconium hydride block material under normal pressure by reducing the hydrogenation rate and the cooling rate, which has the problems of slow hydrogenation rate, long preparation period, high cost and difficult control of hydrogen atom density; third, as the volume of the zirconium block increases, the ratio of hydrogen to zirconium stoichiometry decreases. For large zirconium materials, due to the hydrogenation method, the hydrogen permeation is not uniform, and the hydrogen atom density cannot be controlled, so the ratio of hydrogen to zirconium stoichiometry decreases. Therefore, it is urgent to propose a large-size zirconium hydride block preparation method which is simple in process, free of cracks and good in stability. SUMMARY
[0004] In order to solve the above technical problems, the application provides a preparation method of large-size high-stability zirconium hydride. The application adopts powder metallurgy technology to mix, press and sinter the zirconium hydride powder, and finally prepares a large-size zirconium hydride block material which has good thermal stability and stable hydrogen to zirconium stoichiometric ratio.
[0005] The application discloses a preparation method of large-size high-stability zirconium hydride, which comprises the following steps: zirconium hydride powder and binder powder are weighed according to mass percentage, the powder is mixed and then put into a ball mill for ball milling, the powder after ball milling is grinded and sieved, the powder passing through the sieve is loaded into a mold, then cold isostatic pressing is performed on the mold, the zirconium hydride blank formed by pressing is put into a sintering furnace for sintering, and the zirconium hydride bulk material is obtained after sintering.
[0006] Further, the use amount of zirconium hydride accounts for 98-99wt%, and the use amount of the binder accounts for 1-2wt%.
[0007] Further, the binder is at least one of polyvinyl alcohol, polyvinyl butyral and polyvinyl chloride.
[0008] Further, the ball milling process is that the zirconium hydride powder and the binder powder weighed according to the proportion are mixed and then placed in a ball mill jar, zirconium oxide ball milling balls are added according to a mass ratio of 4:1, and ball milling is performed at a rotating speed of 180r / min for 8h.
[0009] Further, the grinded and sieved process is that the powder after ball milling is grinded and sieved through a 200-mesh sieve.
[0010] Further, the cold isostatic pressing process is that the powder is loaded into a mold, the mold is sealed after vacuumizing and sealing, and then cold isostatic pressing is performed on the mold in a cold isostatic pressing machine, the pressing pressure of the cold isostatic pressing is set to 100-300MPa, the pressure maintaining time is set to 10-20min, and the pressure releasing speed is set to 3MPa / s.
[0011] Further, the mold is a hard rubber short pipe mold.
[0012] Further, the sintering process is that the zirconium hydride blank formed by pressing is put into an atmosphere sintering furnace for sintering, the sintering temperature is set to 300-500 DEG C, and the holding time is set to 0.5-3h.
[0013] Further, the atmosphere is carbon dioxide.
[0014] Further, the zirconium hydride bulk material is taken out after being cooled to room temperature with the furnace.
[0015] The application provides a preparation method of large-size high-stability zirconium hydride. BRIEF DESCRIPTION OF DRAWINGS
[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings used in the embodiment description will be briefly introduced. Obviously, the drawings described below are only some of the embodiments described in the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.
[0017] Figure 1 XRD spectra of zirconium hydride sintered in CO2 atmosphere for embodiments 1-4.
[0018] Figure 2 XRD spectra of zirconium hydride prepared in embodiment 1 before and after annealing at 600 DEG C. DETAILED DESCRIPTION
[0019] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.
[0020] Unless specifically indicated, all the temperatures in the present application are in Celsius, and each preferred solution can be freely combined as needed. Those skilled in the art can understand that the data and various parameters recorded in the embodiments are only exemplary and do not constitute a limitation on the present application. Each component used in the following examples and comparative examples is a compound known in the art, and the equipment used is well known in the art. Each component and equipment used in the present application can be obtained by commercial means or prepared by known technology.
[0021] The application provides a preparation method of large-size high-stability zirconium hydride, which comprises the following steps: taking zirconium hydride powder and binder powder according to the mass percentage, mixing the powders, putting the mixed powders into a ball mill for ball milling, grinding the ball-milled powders and sieving, putting the sieved powders into a mold, cold isostatic pressing the mold, putting the pressed zirconium hydride blank into a sintering furnace for sintering, and taking out the zirconium hydride bulk material after the zirconium hydride bulk material is cooled to room temperature in the furnace.
[0022] Preferably, the use amount of zirconium hydride accounts for 98-99wt%, and the use amount of the binder accounts for 1-2wt%.
[0023] Preferably, the binder is at least one of polyvinyl alcohol, polyvinyl butyral and polyvinyl chloride.
[0024] Preferably, the ball milling process is that the proportionally taken zirconium hydride powder and binder powder are mixed and then put into a ball mill tank, zirconium oxide ball milling balls are added according to the mass ratio of 4:1, and ball milling is carried out at a rotation speed of 180r / min for 8h.
[0025] Preferably, the grinding and sieving process is that the ball-milled powders are ground and sieved through a 200-mesh sieve.
[0026] Preferably, the cold isostatic pressing process is that the powders are put into a mold, the mold is sealed after vacuumizing and sealing, and then cold isostatic pressing is carried out in a cold isostatic pressing machine, the pressing pressure of the cold isostatic pressing is set to 100-300MPa, the pressure holding time is 10-20min, and the pressure releasing speed is 3MPa / s. More preferably, the mold is a hard rubber short pipe mold.
[0027] Preferably, the sintering process is that the pressed zirconium hydride blank is put into an atmosphere sintering furnace for sintering, the sintering temperature is set to 300-500℃, and the holding time is 0.5-3h. More preferably, the atmosphere is carbon dioxide.
[0028] The technical principle of preparing the large-size high-stability zirconium hydride bulk material is that the zirconium hydride powder is pressed into a block-shaped zirconium hydride blank through cold isostatic pressing, the mechanical strength of the block-shaped zirconium hydride is enhanced through the binder, and a zirconium oxide film is formed on the surface of the block-shaped zirconium hydride material through sintering, which is used for enhancing the thermal stability of the block-shaped zirconium hydride. The composite forming of the zirconium hydride is realized through ball milling and cold isostatic pressing, and the preparation of the large-size zirconium hydride material can be realized through the size control of the hard rubber short pipe mold.
[0029] The application will be described in more detail below with reference to exemplary embodiments. The following examples or experimental data are intended to exemplarily illustrate the application, and it should be clear for those skilled in the art that the application is not limited to these examples or experimental data.
[0030] Example 1 Preparation of large-size high-stability zirconium hydride bulk material, comprising the following steps: S1. batching 9.9 kg of zirconium hydride powder, 0.1 kg of polyvinyl butyral powder, wherein the average particle size of the zirconium hydride powder is 4 μm, and the average particle size of the polyvinyl butyral powder is 10 μm; S2. Ball milling After mixing the zirconium hydride and polyvinyl butyral powders, they are placed in a ball mill tank, and zirconia milling balls are added according to a mass ratio of 4:1 to carry out ball milling at a speed of 180 r / min for 8 h; after multiple batches of ball milling, ball milling of all raw materials is completed; S3. Sieving The milled powder is ground and sieved through a 200-mesh sieve; S4. Molding The powder passing through the sieve is loaded into a hard rubber short tube mold with an inner diameter of 55 mm, and after vacuum sealing and sealing, it is placed in a cold isostatic pressing machine; S5. Cold isostatic pressing The cold isostatic pressing pressure is set to 200 MPa, and the pressure holding time is 15 min; after the pressure holding of the cold isostatic pressing is completed, the pressure is released at a speed of 3 MPa / s to obtain a block-shaped zirconium hydride blank; S6. Sintering The block-shaped zirconium hydride blank is placed in an atmosphere furnace for sintering, the sintering temperature is 400℃, the holding time is 2 h, the sintering atmosphere is CO2, and after the sintering program is completed, the furnace is cooled to room temperature to obtain a block-shaped zirconium hydride.
[0031] Example 2 Preparation of large-size high-stability zirconium hydride bulk material, comprising the following steps: S1. batching 9.8 kg of zirconium hydride powder, 0.2 kg of polyvinyl alcohol powder, wherein the average particle size of the zirconium hydride powder is 4 μm, and the average particle size of the polyvinyl alcohol powder is 10 μm; S2. Ball milling After mixing the zirconium hydride and polyvinyl alcohol powders, they are placed in a ball mill tank, and zirconia milling balls are added according to a mass ratio of 4:1 to carry out ball milling at a speed of 180 r / min for 8 h; after multiple batches of ball milling, ball milling of all raw materials is completed; S3. Sieving The milled powder is ground and sieved through a 200-mesh sieve; S4. Molding The powder passing through the screen is loaded into a hard rubber short tube mold with a volume of 120 mm x 120 mm x 12 mm, and after vacuum sealing and sealing, it is placed in a cold isostatic pressing machine; S5. Cold isostatic pressing The cold isostatic pressing pressure is set to 300 MPa, the pressure holding time is 10 min, and after the pressure holding of the cold isostatic pressing is completed, the pressure is released at a speed of 3 MPa / s to obtain a blocky zirconium hydride blank; S6. Sintering The blocky zirconium hydride blank is placed in an atmosphere furnace for sintering, the sintering temperature is 500℃, the holding time is 0.5 h, the sintering atmosphere is CO2, and after the sintering program is completed, the furnace is cooled to room temperature to obtain a blocky zirconium hydride.
[0032] Example 3 Preparation of large-size high-stability zirconium hydride block material, comprising the following steps: S1. Proportioning 9.85 kg of zirconium hydride powder and 0.15 kg of polyvinyl chloride powder are weighed, wherein the average particle size of the zirconium hydride powder is 4 μm, and the average particle size of the polyvinyl chloride powder is 10 μm; S2. Ball milling After the zirconium hydride and polyvinyl chloride powders are mixed, they are placed in a ball mill tank, and zirconia ball milling balls are added according to a mass ratio of ball to material of 4:1 for ball milling at a speed of 180 r / min for 8 h; after multiple batches of ball milling, ball milling of all raw materials is completed; S3. Screening The milled powder is ground and screened through a 200-mesh screen; S4. Molding The powder passing through the screen is loaded into a hard rubber short tube mold with an inner diameter of 55 mm, and after vacuum sealing and sealing, it is placed in a cold isostatic pressing machine; S5. Cold isostatic pressing The cold isostatic pressing pressure is set to 100 MPa, the pressure holding time is 20 min, and after the pressure holding of the cold isostatic pressing is completed, the pressure is released at a speed of 3 MPa / s to obtain a blocky zirconium hydride blank; S6. Sintering The blocky zirconium hydride blank is placed in an atmosphere furnace for sintering, the sintering temperature is 300℃, the holding time is 3 h, the sintering atmosphere is CO2, and after the sintering program is completed, the furnace is cooled to room temperature to obtain a blocky zirconium hydride.
[0033] Example 4 The process for preparing a large-size high-stability zirconium hydride block material in this example is the same as that in Example 1, except that the sintering temperature and holding time are different. In this example, the sintering temperature is 500℃ and the holding time is 1 h.
[0034] Thermal stability analysis and exploration of zirconium hydride bulk materials XRD analysis was performed on the large-size, highly stable zirconium hydride bulk materials prepared in Examples 1-4. Figure 1 The XRD patterns of zirconium hydride in Examples 1-4 are shown below. Figure 1 It is known that the main component of zirconium hydride after sintering in a CO2 atmosphere is still ZrH2, with a very small amount of ZrO2. It is evident that a zirconium oxide film forms on the surface of the bulk zirconium hydride material after sintering in a CO2 atmosphere. Observation of the zirconium hydride bulk materials prepared in Examples 1-4 shows that there are no cracks on the surface of the bulk materials, not even microcracks. This indicates that the large-size zirconium hydride bulk materials prepared by the method of this invention do not suffer from hydrogen-induced cracking or high-temperature hydrogen loss, and will not lead to the breakage of the zirconium hydride bulk material. Moreover, the stoichiometric ratio of hydrogen to zirconium in zirconium hydride does not decrease with the increase of the bulk size. The zirconium hydride bulk materials prepared in each embodiment of this invention are all ZrH2 materials.
[0035] The zirconium hydride bulk material prepared in Example 1 was vacuum annealed at 600°C for 1 hour. XRD analysis was performed on the zirconium hydride before and after annealing, and the results are as follows: Figure 2 As shown, after annealing at 600℃, the composition of the bulk zirconium hydride material remained unchanged, still being ZrH2, and no new components appeared. This demonstrates that the sintering process of this invention can form a zirconium oxide film on the surface of the bulk zirconium hydride material, thereby significantly enhancing the thermal stability of the bulk zirconium hydride. Even after annealing at 600℃, the chemical structure of the ZrH2 material remains stable and reliable.
[0036] All materials used in this invention are commercially available and can be purchased from retail sources. The above description is merely a preferred embodiment of the invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.
Claims
1. A method for preparing large-size, highly stable zirconium hydride, characterized in that, The preparation method includes the following steps: weighing zirconium hydride powder and binder powder according to mass percentage, mixing the powder and putting it into a ball mill for ball milling, grinding the ball-milled powder and sieving it, loading the powder that has passed through the sieve into a mold, then performing cold isostatic pressing on the mold, placing the pressed zirconium hydride billet into a sintering furnace for firing, and obtaining zirconium hydride bulk material after firing.
2. The method for preparing large-size, highly stable zirconium hydride according to claim 1, characterized in that, The amount of zirconium hydride used is 98-99 wt%, and the amount of binder used is 1-2 wt%.
3. The method for preparing large-size, highly stable zirconium hydride according to claim 1, characterized in that, The adhesive is at least one of polyvinyl alcohol, polyvinyl butyral, and polyvinyl chloride.
4. The method for preparing large-size, highly stable zirconium hydride according to claim 1, characterized in that, The ball milling process involves mixing zirconium hydride powder and binder powder according to a certain ratio and placing them in a ball milling jar. Zirconia grinding balls are added at a mass ratio of 4:1, and the mixture is ball milled at a speed of 180 r / min for 8 hours.
5. The method for preparing large-size, highly stable zirconium hydride according to claim 1, characterized in that, The grinding and sieving process involves grinding the ball-milled powder and passing it through a 200-mesh sieve.
6. The method for preparing large-size, highly stable zirconium hydride according to claim 1, characterized in that, The cold isostatic pressing process involves loading powder into a mold, sealing the mold by vacuuming, and then placing it into a cold isostatic press for cold isostatic pressing. The pressing pressure is set to 100~300MPa, the holding time is 10~20min, and the depressurization speed is 3MPa / s.
7. The method for preparing large-size, highly stable zirconium hydride according to claim 6, characterized in that, The mold is a hard rubber short tube mold.
8. The method for preparing large-size, highly stable zirconium hydride according to claim 1, characterized in that, The firing process involves placing the pressed zirconium hydride billet into an atmosphere sintering furnace for firing, setting the sintering temperature to 300~500℃, and the holding time to 0.5~3h.
9. The method for preparing large-size, highly stable zirconium hydride according to claim 8, characterized in that, The atmosphere is carbon dioxide.
10. The method for preparing large-size, highly stable zirconium hydride according to claim 1, characterized in that, The zirconium hydride bulk material was removed after cooling to room temperature in the furnace.