Radiation-resistant low-expansion fluoride glass and preparation method thereof

Abstract

The invention discloses radiation-resistant low-expansion fluoride glass and a preparation method thereof, and relates to the technical field of novel glass. All the components of the fluoride glass provided by the invention are fluorine-containing compounds, and the fluoride glass comprises ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6, and the mole percent of all the components is (40 to 55): (10 to 15): (10 to 15): (5 to 10): (5 to 10): (2 to 5): (3 to 5): (5 to 10): (5 to 10). The fluoride glass with excellent performance is prepared from the raw materials through the steps of vacuum drying, grinding and screening, ball milling, tubular furnace melting, forming, annealing treatment and the like, impurities and internal stress in the prepared fluoride glass can be reduced through the preparation process, stable glass performance is guaranteed, and the fluoride glass is suitable for the related fields of optics, radiation resistance and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new glass, in particular to a kind of radiation-resistant low-expansion fluoride glass and preparation method thereof. BACKGROUND

[0002] The fluoride glass has significant application potential in related fields due to excellent optical transmittance, but the existing fluoride glass generally has insufficient radiation resistance, and is prone to lattice defect accumulation under long-term radiation environment, resulting in decreased light transmittance and deteriorated structural stability, and the thermal expansion coefficient of some products is high, which is prone to deformation or even cracking under temperature fluctuation conditions, affecting the service life of the device. At the same time, improper handling of fluorine-containing raw materials in traditional preparation process can further exacerbate the defects of mechanical properties and optical properties of fluoride glass, which is difficult to meet the requirements of material stability and reliability in high-end fields. Therefore, to meet the increasingly stringent performance requirements of glass materials in the fields of optical engineering, radiation detection, high-temperature environment devices and the like, it is an important research direction in the field of fluoride glass materials to develop fluoride glass with optimized components, excellent radiation resistance and low expansion, and to build a preparation process that can effectively control impurities and reduce internal stress. SUMMARY

[0003] In view of the deficiencies of the prior art, the present application provides a kind of radiation-resistant low-expansion fluoride glass and preparation method thereof. The present application prepares fluoride glass with excellent performance by vacuum drying, grinding and screening, ball milling, tube furnace melting, shaping and annealing of various fluoride raw materials, and the preparation process of the present application can reduce impurities and internal stress in the prepared fluoride glass, ensuring stable glass performance and being suitable for optical, radiation-resistant and other related fields.

[0004] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0005] In a first aspect, the present application provides a kind of radiation-resistant low-expansion fluoride glass, all component ingredients of the radiation-resistant low-expansion fluoride glass are fluorine-containing compounds;The fluorine-containing compounds include ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6;The mole percentage of ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 is (40-55):(10-15):(10-15):(5-10):(5-10):(2-5):(3-5):(5-10):(5-10).

[0006] By specific proportioning of fluorine-containing compounds, low-expansion coefficient, high radiation resistance and good chemical stability of the glass are achieved.

[0007] In the present application, ZrF4 forms the skeleton of the fluoride glass network, in which the rigid structure of Zr-F bond provides basic stability. In addition, CaF2, BaF2 and SrF2 act as crystal network modifiers, by introducing larger Ca 2+ , Ba 2+ and Sr 2+ ions, fill the interstitial space of the crystal network, and inhibit the volume expansion of the crystal caused by thermal vibration generated by radiation. At the same time, the addition of LiF, NaF, AlF3 and Na3AlF6 introduces small-sized lithium ions, sodium ions and aluminum ions, which further fill the interstitial space of the crystal network, and cooperate with ZrF4, BaF2 and SrF2, just like further filling small stones and sand into a container full of large stones, to promote the densification of the crystal network of the fluoride glass, thereby further reducing its thermal expansion coefficient. At the same time, the mutual bonding between various metal ions and fluorine ions significantly enhances the structural rigidity of the crystal network of the prepared fluoride glass, which in turn can reduce radiation-induced structural defects and improve radiation resistance. Finally, CeF3 introduces Ce elements in the fluoride glass, because its outer electron configuration is unique 4f 1 5d 1 6s 2 , so that two valence states of Ce 3+ and Ce 4+ can exist stably in the fluoride glass, and the two valence states can be converted by capturing free electrons and holes generated by radiation, thereby blocking the formation of crystal color centers and further improving radiation resistance.

[0008] In a second aspect, the present application provides a method for preparing a radiation-resistant low-expansion fluoride glass, comprising the following steps:

[0009] S1, placing each component containing a fluorine compound in a crucible, placing the crucible in a vacuum drying box, and obtaining dried raw materials after drying;

[0010] S2, transferring the dried raw materials to a mortar, grinding and then passing through a nylon screen to obtain screened raw materials;

[0011] S3, mixing the screened raw materials weighed in proportion, adding to a maroon ball mill tank, adding ball milling medium, controlling the ball-to-material ratio and ball milling speed, and obtaining mixed raw materials after ball milling under the protection of inert gas;

[0012] S4, loading the mixed raw materials into a crucible and placing it in a tube furnace, introducing inert gas, first purging at a first flow rate for 30-60 min, and then maintaining a second flow rate for continuous aeration;

[0013] S5, increasing the temperature of the tube furnace from room temperature to 400℃ at a first heating rate, maintaining for 1-2 h, and then increasing to 700℃ at a second heating rate and maintaining for 2-3 h to obtain molten mixed raw materials;

[0014] S6, pouring the molten mixed raw materials into a preheated mold while hot, and naturally cooling to room temperature to obtain a shaped glass;

[0015] S7, placing the shaped glass and the mold into an annealing furnace, and obtaining the radiation-resistant low-expansion fluoride glass after annealing treatment.

[0016] In an embodiment, in S1, the specific parameters of drying are as follows: temperature 120-150℃, pressure 10-50Pa, and drying time 4-6h.

[0017] In the present application, the temperature of drying is higher than the boiling point of water but lower than the decomposition temperature of the fluoride used, and the low-pressure environment of the vacuum drying box ensures rapid removal of water and prevents the generation of HF gas to corrode the glass structure during subsequent high-temperature treatment.

[0018] In an embodiment, in S2, the grinding time is 1-2h, and the mesh number of the nylon screen is 100-200.

[0019] In the present application, ball milling under the protection of inert gas after water removal can avoid the reaction of fluoride raw materials; grinding and crushing the raw material particles and sieving to remove coarse particles can avoid local composition unevenness or the generation of unmelted residues during melting.

[0020] In an embodiment, in S3, the ball-to-material ratio is 3:1, the ball milling speed is 200-300r / min, and the ball milling time is 2-4h.

[0021] A ball-to-material ratio of 3:1 provides sufficient mechanical impact force to break up agglomerates in the raw materials; a moderate speed can avoid excessive heating that causes structural damage to the composition of the glass raw materials; and the control of the ball milling time can balance the dispersion effect and energy consumption, and also prevent the introduction of other impurities due to excessive grinding.

[0022] In an embodiment, in S3 and S4, the inert gas includes any one of nitrogen, argon, and a mixed gas of nitrogen and argon; in the mixed gas of nitrogen and argon, the volume ratio of nitrogen to argon is (20-30):(70-80).

[0023] In an embodiment, in S4, the first flow rate is 50-60mL / min, and the second flow rate is 20-30mL / min.

[0024] Using nitrogen, argon, or a mixed gas of the two, first rapid purging and then stable aeration can effectively isolate oxygen and moisture.

[0025] For a feasible embodiment, in S5, the first heating rate is 5-10℃ / min, and the second heating rate is 30-50℃ / min.

[0026] In the present application, slow heating from room temperature to 400℃ can avoid the breakage of raw materials due to thermal stress; and accelerating the heating from 400℃ to 700℃ can reduce the decomposition and volatilization of raw material components at high temperature.

[0027] For a feasible embodiment, in S6, the preheated mold includes any one of a graphite mold and a silicon carbide mold; and the preheating temperature is 300-400℃.

[0028] In the present application, the graphite mold or the silicon carbide mold has a much higher thermal conductivity than the ordinary mold, and the graphite mold or the silicon carbide mold can quickly absorb heat during preheating, and the overall temperature is uniform; therefore, after the molten glass liquid is poured in, the mold can uniformly conduct heat, avoiding the occurrence of non-uniform temperature at the interface between the glass and the mold, so as to reduce the stress of the molten fluoride during forming, and further prevent cracks.

[0029] For a feasible embodiment, in S7, the annealing process includes:

[0030] First, the temperature is raised to 350-400℃ at a rate of 5-10℃ / min, then the temperature is kept for 2-4h, and finally the temperature is reduced to 100℃ at a rate of 1-2℃ / min, and then the product is naturally cooled to room temperature.

[0031] In the present application, the further annealing process is to first raise the temperature to 350-400℃, which can relax the internal structure of the prepared glass, combined with sufficient holding time, so as to fully release the stress therein; and then slowly cooling to avoid the formation of secondary stress.

[0032] Beneficial technical effects:

[0033] In the present application, ZrF4 is used to form the skeleton of fluoride glass network, in which the rigid structure of Zr-F bond provides basic stability. In addition, CaF2, BaF2 and SrF2 are used as crystal network modifiers, which can introduce larger Ca 2+ , Ba 2+ and Sr 2+Ions fill the gaps in the crystal network, suppressing the crystal volume expansion caused by thermal vibrations induced by radiation. Simultaneously, the addition of LiF, NaF, AlF3, and Na3AlF6 introduces small-sized lithium, sodium, and aluminum ions, further filling the gaps in the crystal network. These ions, in conjunction with ZrF4, BaF2, and SrF2, act like adding pebbles and sand to a container already full of large rocks, promoting the densification of the crystal network in the fluoride glass and thus further reducing its coefficient of thermal expansion. Furthermore, the bonding between various metal ions and fluoride ions significantly enhances the structural rigidity of the resulting fluoride glass crystal network, thereby reducing radiation-induced structural defects and improving radiation resistance. Finally, Ce is introduced into the fluoride glass via CeF3, due to its unique 4f outer electron configuration. 1 5d 1 6s 2 Therefore, Ce can exist stably in fluoride glasses. 3+ and Ce 4+ The two valence states can interconvert by capturing free electrons and holes generated by radiation, thereby blocking the formation of crystal color centers and further improving radiation resistance. Simultaneously, by combining raw material dehydration and ball milling for homogenization, effective inert atmosphere protection during melting, the use of matching graphite or silicon carbide molds, and temperature control during annealing, the resulting fluoride glass possesses radiation resistance, low expansion, high chemical stability, and structural integrity, making it suitable for various demanding applications. Attached Figure Description

[0034] Figure 1 This is a schematic flowchart of a method for preparing radiation-resistant, low-expansion fluoride glass according to an embodiment of this application. Detailed Implementation

[0035] To facilitate understanding of the content described in this application, the technical solutions described herein are further explained below with reference to specific embodiments; however, this application is not limited thereto. All equivalent transformations or simple substitutions made based on the substantive content of this application should fall within the protection scope of this application.

[0036] The singular forms “for,” “or,” “a,” “any,” and “the” used in this application are intended to include the plural forms unless the context clearly indicates otherwise.

[0037] The following describes in detail, with reference to different embodiments, the preparation method of the radiation-resistant, low-expansion fluoride glass provided in this application.

[0038] Example 1

[0039] like Figure 1As shown in the preparation method of a radiation-resistant low-expansion fluoride glass comprises the following steps:

[0040] S1, ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 are placed in a crucible, the crucible is placed in a vacuum drying box, and after drying, dry raw materials are obtained; wherein the molar percentage of ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 is: 45:12:12:7:6:3:4:6:5; The specific parameters of vacuum drying are: temperature 130℃, pressure 20Pa, and drying time 5h;

[0041] S2, the dry raw materials are transferred to a mortar, ground and sieved through a nylon screen to obtain a sieved raw material; wherein the grinding time is 1.5h, and the mesh size of the nylon screen is 150 mesh;

[0042] S3, the sieved raw material mixed in proportion is added to an agate ball mill tank, the ball milling medium is added, the ball-to-material ratio and the ball milling speed are controlled, and after ball milling under nitrogen protection, the mixed raw material is obtained; wherein the ball-to-material ratio is 3:1, the ball milling speed is 250r / min, and the ball milling time is 3h;

[0043] S4, the mixed raw material is loaded into a crucible and placed in a tube furnace, nitrogen is introduced, first at a first flow rate of 55mL / min for 45min, and then at a second flow rate of 25mL / min for continuous aeration;

[0044] S5, the temperature of the tube furnace is increased from room temperature to 400℃ at a first heating rate of 8℃ / min, and then increased to 700℃ at a second heating rate of 40℃ / min and kept for 2.5h, to obtain a molten mixed raw material;

[0045] S6, the molten mixed raw material is poured into a preheated graphite mold with a temperature of 350℃ while hot, and naturally cooled to room temperature to obtain a shaped glass;

[0046] S7, the shaped glass and the mold are placed in an annealing furnace, and after annealing treatment, the radiation-resistant low-expansion fluoride glass is obtained; wherein the annealing process comprises: first increasing the temperature to 380℃ at a rate of 8℃ / min, then keeping for 3h, and finally decreasing to 100℃ at a rate of 1.5℃ / min, and then taking out and naturally cooling to room temperature.

[0047] Example 2

[0048] As Figure 1 shown, a preparation method of a radiation-resistant low-expansion fluoride glass comprises the following steps:

[0049] S1, ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 are respectively placed in a crucible, the crucible is placed in a vacuum drying box, and after drying, dry raw materials are obtained; wherein the molar percentage of ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 is: 40:15:10:5:5:5:5:5:10; the specific parameters of vacuum drying are: temperature 120℃, pressure 10Pa, and drying time 6h;

[0050] S2, the dry raw materials are transferred to a mortar, ground and sieved through a nylon screen to obtain a sieved raw material; wherein the grinding time is 2h, and the mesh number of the nylon screen is 200 meshes;

[0051] S3, the sieved raw material weighed in proportion is mixed and added to a agate ball mill tank, ball milling medium is added, the ball-to-material ratio and the ball milling speed are controlled, and after ball milling under nitrogen protection, a mixed raw material is obtained; wherein the ball-to-material ratio is 3:1, the ball milling speed is 200r / min, and the ball milling time is 4h;

[0052] S4, the mixed raw material is loaded into a crucible and placed in a tube furnace, nitrogen is introduced, first purged at a first flow rate of 50mL / min for 60min, and then continuously ventilated at a second flow rate of 20mL / min;

[0053] S5, the temperature of the tube furnace is increased from room temperature to 400℃ at a first heating rate of 5℃ / min, then increased to 700℃ at a second heating rate of 30℃ / min after keeping for 2h, and kept for 3h to obtain a molten mixed raw material;

[0054] S6, the molten mixed raw material is poured into a preheated silicon carbide mold with a preheating temperature of 300℃ while hot, and naturally cooled to room temperature to obtain a shaped glass;

[0055] S7, the shaped glass and the mold are placed in an annealing furnace together, and after annealing treatment, the radiation-resistant low-expansion fluoride glass is obtained; wherein the annealing process includes: first increasing the temperature to 350℃ at a rate of 5℃ / min, then keeping for 4h, and finally decreasing to 100℃ at a rate of 1℃ / min, and then taking out and naturally cooling to room temperature.

[0056] Example 3

[0057] As Figure 1 shown, a preparation method of a radiation-resistant low-expansion fluoride glass comprises the following steps:

[0058] S1, ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 are respectively placed in a crucible, the crucible is placed in a vacuum drying box, and after drying, dry raw materials are obtained; wherein the molar percentage of ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 is: 45:10:10:10:5:2:3:8:7; the specific parameters of vacuum drying are: temperature 150℃, pressure 50Pa, and drying time 4h;

[0059] S2, the dry raw materials are transferred to a mortar, ground and sieved through a nylon screen to obtain a sieved raw material; wherein the grinding time is 1h, and the mesh size of the nylon screen is 100 meshes;

[0060] S3, the sieved raw material mixed in proportion is added to a maroon ball mill tank, a ball milling medium is added, the ball-to-material ratio and the ball milling speed are controlled, and after ball milling under the protection of a mixed gas of nitrogen and argon, a mixed raw material is obtained; wherein the ball-to-material ratio is 3:1, the ball milling speed is 300r / min, the ball milling time is 2h, and the volume ratio of nitrogen to argon is 25:75;

[0061] S4, the mixed raw material is loaded into a crucible and placed in a tube furnace, a mixed gas of nitrogen and argon is introduced, first purged at a first flow rate of 60mL / min for 30min, and then continuously ventilated at a second flow rate of 30mL / min; the volume ratio of nitrogen to argon is 25:75;

[0062] S5, the temperature of the tube furnace is increased from room temperature to 400℃ at a first heating rate of 10℃ / min, then increased to 700℃ at a second heating rate of 50℃ / min after maintaining for 1h, and the molten mixed raw material is obtained;

[0063] S6, the molten mixed raw material is poured into a preheated graphite mold with a preheating temperature of 400℃ while hot, and naturally cooled to room temperature to obtain a shaped glass;

[0064] S7, the shaped glass and the mold are placed in an annealing furnace together, and after annealing treatment, the radiation-resistant low-expansion fluoride glass is obtained; wherein the annealing process includes: first increasing the temperature to 400℃ at a rate of 10℃ / min, then maintaining for 2h, and finally decreasing to 100℃ at a rate of 2℃ / min, and then taking out and naturally cooling to room temperature.

[0065] Example 4

[0066] As Figure 1 shown, a preparation method of a radiation-resistant low-expansion fluoride glass comprises the following steps:

[0067] S1, ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 are respectively placed in a crucible, the crucible is placed in a vacuum drying box, and after drying, dry raw materials are obtained; wherein the molar percentage of ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 is: 55:10:10:5:5:2:3:5:5; the specific parameters of vacuum drying are: temperature 135℃, pressure 30Pa, and drying time 4.5h;

[0068] S2, the dry raw materials are transferred to a mortar, ground and sieved through a nylon screen to obtain sieved raw materials; wherein the grinding time is 1.5h, and the mesh size of the nylon screen is 150 meshes;

[0069] S3, the sieved raw materials are mixed after being weighed in proportion, and then added to a agate ball mill tank, ball milling medium is added, the ball-to-material ratio and the ball milling speed are controlled, and after ball milling under the protection of a mixed gas of nitrogen and argon, a mixed raw material is obtained; wherein the ball-to-material ratio is 3:1, the ball milling speed is 250r / min, and the ball milling time is 2.5h; the volume ratio of nitrogen to argon is 20:80;

[0070] S4, the mixed raw material is loaded into a crucible and placed in a tube furnace, a mixed gas of nitrogen and argon is introduced, first purged at a first flow rate of 55mL / min for 40min, and then continuously ventilated at a second flow rate of 25mL / min; the volume ratio of nitrogen to argon is 20:80;

[0071] S5, the temperature of the tube furnace is increased from room temperature to 400℃ at a first heating rate of 8℃ / min, maintained for 1.5h, then increased to 700℃ at a second heating rate of 45℃ / min and maintained for 2.5h, to obtain a molten mixed raw material;

[0072] S6, the molten mixed raw material is poured into a preheated silicon carbide mold with a preheating temperature of 350℃ while hot, and naturally cooled to room temperature to obtain a shaped glass;

[0073] S7, the shaped glass and the mold are placed in an annealing furnace, and after annealing treatment, the radiation-resistant low-expansion fluoride glass is obtained; wherein the annealing process includes: first increasing the temperature to 350℃ at a rate of 8℃ / min, then maintaining for 2.5h, and finally decreasing to 100℃ at a rate of 1.5℃ / min, and then taking out and naturally cooling to room temperature.

[0074] Example 5

[0075] As Figure 1 shown, a preparation method of a radiation-resistant low-expansion fluoride glass comprises the following steps:

[0076] S1, ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 are respectively placed in a crucible, the crucible is placed in a vacuum drying box, and after drying, dry raw materials are obtained; wherein the molar percentage of ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 is: 46:10:12:5:5:3:4:10:5; the specific parameters of vacuum drying are: temperature 140℃, pressure 40Pa, and drying time 5.5h;

[0077] S2, the dry raw materials are transferred to a mortar, ground and sieved through a nylon screen to obtain sieved raw materials; wherein the grinding time is 1.5h, and the mesh size of the nylon screen is 120 meshes;

[0078] S3, the sieved raw materials are mixed after being weighed in proportion, and then added to a maroon ball mill tank, ball milling medium is added, the ball-to-material ratio and the ball milling speed are controlled, and after ball milling under the protection of a mixed gas of nitrogen and argon, a mixed raw material is obtained; wherein the ball-to-material ratio is 3:1, the ball milling speed is 200r / min, and the ball milling time is 3.5h; the volume ratio of nitrogen to argon is 30:70;

[0079] S4, the mixed raw material is loaded into a crucible and placed in a tube furnace, a mixed gas of nitrogen and argon is introduced, first purged at a first flow rate of 50mL / min for 50min, and then continuously ventilated at a second flow rate of 20mL / min; the volume ratio of nitrogen to argon is 30:70;

[0080] S5, the temperature of the tube furnace is increased from room temperature to 400℃ at a first heating rate of 5℃ / min, maintained for 2h, and then increased to 700℃ at a second heating rate of 40℃ / min and maintained for 3h, to obtain a molten mixed raw material;

[0081] S6, the molten mixed raw material is poured into a preheated graphite mold with a preheating temperature of 320℃ while hot, and naturally cooled to room temperature to obtain a shaped glass;

[0082] S7, the shaped glass and the mold are placed in an annealing furnace together, and after annealing treatment, the radiation-resistant low-expansion fluoride glass is obtained; wherein the annealing process includes: first increasing the temperature to 360℃ at a rate of 5℃ / min, then maintaining for 3.5h, and finally decreasing to 100℃ at a rate of 1℃ / min, and then taking out and naturally cooling to room temperature.

[0083] Example 6

[0084] As Figure 1 shown, a preparation method of a radiation-resistant low-expansion fluoride glass comprises the following steps:

[0085] S1, ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 are respectively placed in a crucible, the crucible is placed in a vacuum drying box, and after drying, dry raw materials are obtained; wherein the molar percentage of ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 is: 43:12:13:7:5:2:5:6:7; the specific parameters of vacuum drying are: temperature 125℃, pressure 25Pa, and drying time 5h;

[0086] S2, the dry raw materials are transferred to a mortar, ground and sieved through a nylon screen to obtain a sieved raw material; wherein the grinding time is 2h, and the mesh number of the nylon screen is 180 meshes;

[0087] S3, the sieved raw material weighed in proportion is mixed and added to a carnelian ball mill tank, ball milling medium is added, the ball-to-material ratio and the ball milling speed are controlled, and after ball milling under argon protection, a mixed raw material is obtained; wherein the ball-to-material ratio is 3:1, the ball milling speed is 250r / min, and the ball milling time is 3h;

[0088] S4, the mixed raw material is loaded into a crucible and placed in a tube furnace, argon is introduced, first purged at a first flow rate of 50mL / min for 40min, and then continuously ventilated at a second flow rate of 25mL / min;

[0089] S5, the temperature of the tube furnace is increased from room temperature to 400℃ at a first heating rate of 5℃ / min, maintained for 1.5h, then increased to 700℃ at a second heating rate of 45℃ / min and maintained for 2h, to obtain a molten mixed raw material;

[0090] S6, the molten mixed raw material is poured into a preheated silicon carbide mold with a preheating temperature of 360℃ while hot, and naturally cooled to room temperature to obtain a shaped glass;

[0091] S7, the shaped glass is placed in an annealing furnace together with the mold, and after annealing treatment, the radiation-resistant low-expansion fluoride glass is obtained; wherein the annealing process includes: first increasing the temperature to 350℃ at a rate of 5℃ / min, then maintaining for 3h, and finally decreasing to 100℃ at a rate of 1.5℃ / min, and then taking out and naturally cooling to room temperature.

[0092] Comparative Example 1

[0093] A preparation method of a radiation-resistant low-expansion fluoride glass, comprising the following steps:

[0094] S1, ZrF4, BaF2, SrF2, CaF2 and CeF3 are respectively placed in a crucible, the crucible is placed in a vacuum drying box, and dry raw materials are obtained after drying; wherein the molar percentage of ZrF4, BaF2, SrF2, CaF2 and CeF3 is: 55:15:15:5:10; the specific parameters of vacuum drying are: temperature 130℃, pressure 20Pa, and drying time 5h;

[0095] S2, the dry raw materials are transferred to a mortar, ground and sieved through a nylon screen to obtain a sieved raw material; wherein the grinding time is 1.5h, and the mesh number of the nylon screen is 150 meshes;

[0096] S3, the sieved raw materials are mixed according to the proportion, then added to a maroon ball mill tank, ball mill medium is added, the ball-to-material ratio and the ball milling speed are controlled, and then the mixed raw materials are obtained after ball milling under nitrogen protection; wherein the ball-to-material ratio is 3:1, the ball milling speed is 250r / min, and the ball milling time is 3h;

[0097] S4, the mixed raw materials are loaded into a crucible and placed in a tube furnace, nitrogen is introduced, first purged at a first flow rate of 55mL / min for 45min, and then continuously ventilated at a second flow rate of 25mL / min;

[0098] S5, the temperature of the tube furnace is increased from room temperature to 400℃ at a first heating rate of 8℃ / min, then kept for 1.5h, and then increased to 700℃ at a second heating rate of 40℃ / min and kept for 2.5h, to obtain molten mixed raw materials;

[0099] S6, the molten mixed raw materials are poured into a preheated graphite mold with a preheating temperature of 350℃ while hot, and naturally cooled to room temperature to obtain a shaped glass;

[0100] S7, the shaped glass and the mold are placed in an annealing furnace together, and the radiation-resistant low-expansion fluoride glass is obtained after annealing treatment; wherein the annealing treatment process comprises: first increasing the temperature to 380℃ at a rate of 8℃ / min, then keeping for 3h, and finally decreasing to 100℃ at a rate of 1.5℃ / min, and then taking out and naturally cooling to room temperature.

[0101] Comparative Example 2

[0102] A preparation method of a radiation-resistant low-expansion fluoride glass, comprising the following steps:

[0103] S1, ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2 and Na3AlF6 are respectively placed in a crucible, the crucible is placed in a vacuum drying box, and after drying, dry raw materials are obtained; wherein the molar percentage of ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2 and Na3AlF6 is: 53:10:10:10:5:2:3:7; the specific parameters of vacuum drying are: temperature 150℃, pressure 50Pa, and drying time 4h;

[0104] S2, the dry raw materials are transferred to a mortar, ground and sieved through a nylon screen to obtain sieved raw materials; wherein the grinding time is 1h, and the mesh size of the nylon screen is 100 meshes;

[0105] S3, the sieved raw materials mixed in proportion are added to a agate ball mill tank, ball milling medium is added, the ball-to-material ratio and the ball milling speed are controlled, and after ball milling under the protection of a mixed gas of nitrogen and argon, a mixed raw material is obtained; wherein the ball-to-material ratio is 3:1, the ball milling speed is 300r / min, the ball milling time is 2h, and the volume ratio of nitrogen to argon is 25:75;

[0106] S4, the mixed raw material is loaded into a crucible and placed in a tube furnace, a mixed gas of nitrogen and argon is introduced, first purged at a first flow rate of 60mL / min for 30min, and then continuously ventilated at a second flow rate of 30mL / min; the volume ratio of nitrogen to argon is 25:75;

[0107] S5, the temperature of the tube furnace is increased from room temperature to 400℃ at a first heating rate of 10℃ / min, then increased to 700℃ at a second heating rate of 50℃ / min after keeping for 1h, and the molten mixed raw material is obtained;

[0108] S6, the molten mixed raw material is poured into a preheated graphite mold with a temperature of 400℃ while hot, and naturally cooled to room temperature to obtain a shaped glass;

[0109] S7, the shaped glass and the mold are placed in an annealing furnace together, and the annealing treatment is carried out to obtain the radiation-resistant low-expansion fluoride glass; wherein the annealing process includes: first increasing the temperature to 400℃ at a rate of 10℃ / min, then keeping for 2h, and finally decreasing to 100℃ at a rate of 2℃ / min, and then taking out and naturally cooling to room temperature.

[0110] Comparative Example 3

[0111] A preparation method of a radiation-resistant low-expansion fluoride glass, comprising the following steps:

[0112] S1, ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 were respectively placed in a crucible, the crucible was placed in a vacuum drying oven, and after drying, dry raw materials were obtained; wherein the molar percentage of ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 was: 43:12:13:7:5:2:5:6:7; the specific parameters of vacuum drying were: temperature 125℃, pressure 25Pa, and drying time 5h;

[0113] S2, the dry raw materials were transferred to a mortar, ground and sieved through a nylon screen to obtain a sieved raw material; wherein the grinding time was 2h, and the mesh size of the nylon screen was 180 meshes;

[0114] S3, the sieved raw material weighed in proportion was mixed and added to a maroon ball mill tank, ball milling medium was added, the ball-to-material ratio and the ball milling speed were controlled, and after ball milling under argon protection, a mixed raw material was obtained; wherein the ball-to-material ratio was 3:1, the ball milling speed was 250r / min, and the ball milling time was 3h;

[0115] S4, the mixed raw material was loaded into a crucible and placed in a tube furnace, argon was introduced, first swept at a first flow rate of 50mL / min for 40min, and then continuously ventilated at a second flow rate of 25mL / min;

[0116] S5, the temperature of the tube furnace was increased from room temperature to 400℃ at a first heating rate of 5℃ / min, maintained for 1.5h, then increased to 700℃ at a second heating rate of 45℃ / min and maintained for 2h, to obtain a molten mixed raw material;

[0117] S6, the molten mixed raw material was poured into a preheated stainless steel mold at a temperature of 360℃ while hot, and naturally cooled to room temperature to obtain a fluoride glass.

[0118] The fluoride glasses prepared in Examples 1-6 and Comparative Examples 1-3 were tested for radiation resistance (X-ray irradiation for 8 hours, working voltage: 100kV, working current: 7mA±0.5mA) and thermal expansion coefficient, wherein the visible light transmittance of the fluoride glass after radiation represented its radiation resistance. The test results are shown in Table 1.

[0119] Table 1 Test results of fluoride glasses prepared in Examples 1-6 and Comparative Examples 1-3 Visible light transmittance (%) after irradiation Coefficient of thermal expansion ( / °C) Example 1 92 6.7 x 10 -7 ]]> Example 2 90 7.2 x 10 -7 ]] Example 3 93 6.4 x 10 -7 ]]> Example 4 91 6.9 x 10 -7 ]]> Example 5 91 7.1 x 10 -7 ]]> Example 6 93 6.5 x 10 -7 ]]> Comparative Example 1 87 3.7 x 10 -6 ]]> Comparative Example 2 79 4.9 x 10 -7 ]] Comparative Example 3 73 5.1 x 10 -6 ]]>

[0120] As can be seen from Table 1, the radiation resistance and low expansion properties of Examples 1-6 are overall better than those of Comparative Examples 1-3.

[0121] The main reason is that embodiments 1-6 form a skeleton of fluoride glass network by ZrF4, in which the rigid structure of Zr-F bond provides basic stability. In addition, CaF2, BaF2 and SrF2 as crystal network modifiers fill the interstitial space of the crystal network by introducing larger Ca 2+ , Ba 2+ and Sr 2+ ions, and inhibit the expansion of the crystal volume caused by thermal vibration due to radiation. At the same time, the addition of LiF, NaF, AlF3 and Na3AlF6 introduces small-sized lithium ions, sodium ions and aluminum ions, which further fill the interstitial space of the crystal network, and cooperate with ZrF4, BaF2 and SrF2, just like further filling small stones and sand into a container full of large stones, promoting the densification of the crystal network in the fluoride glass, thereby further reducing its thermal expansion coefficient. At the same time, the mutual bonding between various metal ions and fluorine ions significantly enhances the structural rigidity of the crystal network of the prepared fluoride glass, which in turn can reduce radiation-induced structural defects and improve radiation resistance. Finally, CeF3 introduces Ce elements in the fluoride glass, because its outer electron configuration is unique 4f 1 5d 1 6s 2 , so in the fluoride glass there are two valence states of Ce 3+ and Ce 4+ , and the two valence states can be converted by capturing free electrons and holes generated by radiation, thereby blocking the formation of crystal color centers and further improving radiation resistance. At the same time, the combination of raw material water removal and ball milling and screening homogenization, effective inert atmosphere protection during melting, matching use of graphite or silicon carbide mold, and temperature control during annealing in the preparation process makes the prepared fluoride glass have radiation resistance, low expansion, high chemical stability and structural integrity, and is suitable for various demanding application scenarios.

[0122] In contrast, the fluoride glass prepared in Comparative Example 1 does not contain LiF, AlF3, NaF and Na3AlF6 in its composition, so it cannot introduce small-sized lithium ions, sodium ions and aluminum ions, thereby failing to further fill the interstitial space of the crystal network and cooperate with ZrF4, BaF2 and SrF2, so the crystal network in the fluoride glass cannot be further densified, and finally its thermal expansion coefficient is high. At the same time, the absence of lithium ions, sodium ions and aluminum ions reduces the mutual bonding between various metal ions and fluorine ions, so the structural rigidity of the crystal network of the fluoride glass is weakened, which in turn makes it difficult to reduce radiation-induced structural defects and reduces radiation resistance.

[0123] The fluoride glass prepared in Comparative Example 2 does not contain CeF3 in its composition, so there is no two-valence-state Ce3+ and Ce 4+ Therefore, it is difficult to block the formation of crystal color centers, and the final fluoride glass has poor radiation resistance but little change in thermal expansion coefficient.

[0124] In the comparative example 3, the stainless steel mold is used without annealing process, so the stress in the prepared fluoride glass is difficult to release in time, and cracks are easily generated, and the stability and structural integrity are poor, the radiation resistance is poor, and the thermal expansion coefficient is large.

[0125] The above results show and describe the basic principles and main features of the present application and the advantages of the present application.

[0126] Those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection claimed by the present application is defined by the equivalents of the appended claims.

Claims

1. A radiation-resistant, low-expansion fluoride glass, characterized in that, All components of the radiation-resistant, low-expansion fluoride glass are fluorine-containing compounds; the fluorine-containing compounds include: ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6; the molar percentages of ZrF4, BaF2, SrF2, LiF, AlF3, NaF, CaF2, CeF3 and Na3AlF6 are: (40~55): (10~15): (10~15): (5~10): (5~10): (2~5): (3~5): (5~10): (5~10).

2. A method for preparing a radiation-resistant, low-expansion fluoride glass, used to prepare the radiation-resistant, low-expansion fluoride glass as described in claim 1, characterized in that, Includes the following steps: S1. Place each component of the fluorine-containing compound into a crucible, place the crucible into a vacuum drying oven, and dry to obtain the dried raw material; S2. Transfer the dried raw material to a mortar, grind it, and then pass it through a nylon sieve to obtain the sieved raw material. S3. After mixing the weighed and screened raw materials according to the proportion, add them to the agate ball mill jar, add the ball milling media, control the ball-to-material ratio and ball milling speed, and ball mill under inert gas protection to obtain the mixed raw materials. S4. Load the mixed raw materials into a crucible, place it in a tube furnace, and introduce inert gas. First, purge at the first flow rate for 30-60 minutes, and then maintain the second flow rate for continuous gas introduction. S5. Raise the temperature of the tube furnace from room temperature to 400°C at the first heating rate, hold for 1-2 hours, then continue to raise the temperature to 700°C at the second heating rate and hold for 2-3 hours to obtain molten mixed raw materials. S6. Pour the molten mixture into a preheated mold and allow it to cool naturally to room temperature to obtain the shaped glass. S7. Place the formed glass and the mold together into an annealing furnace, and after annealing, obtain the radiation-resistant, low-expansion fluoride glass.

3. The method for preparing radiation-resistant, low-expansion fluoride glass according to claim 2, characterized in that, In S1, the specific drying parameters are: temperature 120~150℃, pressure 10~50Pa, and drying time 4~6h.

4. The method for preparing radiation-resistant, low-expansion fluoride glass according to claim 2, characterized in that, In S2, the grinding time is 1~2 hours, and the nylon sieve mesh size is 100~200 mesh.

5. The method for preparing radiation-resistant, low-expansion fluoride glass according to claim 2, characterized in that, In S3, the ball-to-material ratio is 3:1, the ball milling speed is 200~300 r / min, and the ball milling time is 2~4 h.

6. The method for preparing radiation-resistant, low-expansion fluoride glass according to claim 2, characterized in that, In S3 and S4, the inert gas includes any one of nitrogen, argon, and a mixture of nitrogen and argon; in the mixture of nitrogen and argon, the volume ratio of nitrogen to argon is (20~30):(70~80).

7. The method for preparing radiation-resistant, low-expansion fluoride glass according to claim 2, characterized in that, In S4, the first flow rate is 50~60 mL / min, and the second flow rate is 20~30 mL / min.

8. The method for preparing radiation-resistant, low-expansion fluoride glass according to claim 2, characterized in that, In S5, the first heating rate is 5~10℃ / min, and the second heating rate is 30~50℃ / min.

9. The method for preparing radiation-resistant, low-expansion fluoride glass according to claim 2, characterized in that, In S6, the preheated mold includes either a graphite mold or a silicon carbide mold; the preheating temperature is 300~400℃.

10. The method for preparing radiation-resistant, low-expansion fluoride glass according to claim 2, characterized in that, In S7, the annealing process includes: First, raise the temperature to 350-400℃ at a rate of 5-10℃ / min, then keep it at that temperature for 2-4 hours. Finally, lower the temperature to 100℃ at a rate of 1-2℃ / min, and then remove it and let it cool naturally to room temperature.

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