Method for producing high density and bulk polycrystalline quartz aggregates under hot isostatic pressing conditions

Abstract

The application discloses a preparation method of high-density and large bulk polycrystalline quartz aggregate under hot isostatic pressing conditions. –3 The Pa size is 55.94 mm outer diameter*88.77 mm height*3 mm wall thickness, the ladle sleeve is placed in a graphite furnace cylinder body of a hot isostatic pressing high-pressure container and covered with a graphite sealing cover; a multi-gradient hot isostatic pressing method is adopted to increase the temperature and pressure in sequence by taking argon as a pressure transmission medium, the temperature in the cylinder sample bin is increased to 940 DEG C, the pressure is increased to 114.1 MPa, and the temperature and pressure are kept for 4.5 hours; a multi-gradient cylinder temperature and pressure reduction mode is adopted to reduce the temperature in the cylinder sample bin to 180 DEG C, and the pressure is reduced to 72.8 MPa; finally, the pressure is released and the temperature is reduced to room temperature to obtain the polycrystalline quartz aggregate; and the problem of preparation of high-density polycrystalline quartz aggregate bulk experimental samples under high-temperature and high-pressure conditions is solved.

Description

Technical Field

[0001] This invention belongs to the field of experimental sample synthesis technology of bulk framework structured dioxide mineral polymers – polycrystalline quartz group minerals, and particularly relates to a method for preparing high-density and bulk polycrystalline quartz polymers under hot isostatic pressing. Background Technology

[0002] Quartz minerals (chemical formula: SiO2) belong to the group of oxide minerals and are also important end-member components of silicate minerals. O is a basic structural unit in their composition. 2– [SiO4] is shared with and interconnected to form a three-dimensional, infinitely extending framework structure, usually referring to the general term for α-quartz (low-temperature quartz, trigonal crystal system) and β-quartz (high-temperature quartz, hexagonal crystal system). In nature, based on the significant differences in crystal structure properties, the identified polymorphs of quartz mainly include: low-temperature quartz (α-quartz), high-temperature quartz (β-quartz), low-temperature tridymite (α-tridymite), medium-temperature tridymite (β1-tridymite), high-temperature tridymite (β2-tridymite), low-temperature cristobalite (α-cristobalite), high-temperature cristobalite (β-cristobalite), black cristobalite, fibrous silica, opal, kaolinite, stearite, and coesite, totaling 13 types. Recent research in high-pressure mineral physics indicates that due to significant differences in physicochemical conditions such as temperature, pressure, redox state, and volatile composition among different geological structural units deep within the Earth, these visible polymorphic variants can easily undergo interconversion of quartz mineral phases with different structural states. Among these polymorphic variants, low-temperature quartz (α-quartz), high-temperature quartz (β-quartz), low-temperature tridymite (α-tridymite), medium-temperature tridymite (β1-tridymite), high-temperature tridymite (β2-tridymite), low-temperature cristobalite (α-cristobalite), high-temperature cristobalite (β-cristobalite), black cristobalite, fibrous silica, opal, and kaolinite exist in geologically complex environments with lower temperatures and pressures. In contrast, stearite and coesite, which are polymorphic variants, mainly occur in eclogites and kimberlites in ultra-high-pressure metamorphic belts (for example, the most typical exposure is in the Sulu-Dabie Mountains region of eastern China) and in ultra-high-speed, high-pressure meteorite craters (for example, the most typical exposure is in the Yilan meteorite crater in Heilongjiang Province, northeastern China), and exist stably in geologically complex environments with higher temperatures and pressures. The study of the interconversion system of quartz homogeneous polymorphs under physicochemical conditions such as temperature, pressure, redox state, and volatile components is of great scientific significance for in-depth exploration of the composition, structure, and material cycle of the deep Earth and for revealing the evolutionary history of the Earth and planets.

[0003] Quartz is the most widely distributed oxide mineral in the Earth's deep interior, found in all spheres, especially in the middle and lower crust where it is the most important rock-forming mineral, accounting for about 11% of the total continental crust. It possesses excellent physicochemical properties, including hardness, translucency, wear resistance, brittleness, lack of cleavage, acid resistance, greasy luster, and corrosion resistance. In terms of theoretical chemical composition, quartz contains 100% SiO2 oxide or 46.74% Si and 53.26% O. Although natural quartz is relatively pure, isomorphous substitution of silicon in its structure is very common. Silicon can undergo substitution reactions with small amounts of cations such as H, Li, Na, K, Ca, Fe, Mg, Mn, Al, and Ti, forming many different types of vacancies or defects. These defects have a significant impact on the electrical, elastic, viscoelastic, mechanical, and equation of state properties of quartz, particularly exhibiting extremely important anisotropic behavior along the crystal axis.

[0004] As an important end-member component and major rock-forming mineral of silicate minerals, quartz is widely exposed in various geological formations of igneous, sedimentary, and metamorphic rocks. In sedimentary rocks exposed at the surface, quartz is the main component of quartz sandstone; in typical metamorphic rocks exposed at the surface, quartz is the main rock-forming mineral of crystalline schist, quartzite, and gneiss; and in common igneous rocks at the surface, quartz is also a major constituent mineral of granite, andesite, rhyolite, granodiorite, amphibolite, and quartz monzonite. Quartz crystal clusters, arranged in a comb-like structure and exposed as long columnar crystals in veins, are mostly found in pegmatite caves. Quartz contains primarily impurity minerals, which exist as associated minerals, inclusions, and lattice structure impurities. These impurity minerals (such as albite, potassium feldspar, biotite, muscovite, dolomite, calcite, rutile, fluorite, pyrite, and magnetite) not only affect the physicochemical properties of quartz but also determine the difficulty of its purification. Currently, the main quartz mineral resources in nature with important industrial applications include granite pegmatite, quartzite, quartz sandstone, vein quartz, natural crystal, quartz sand, and rose quartz. After comprehensive surveying, exploration, mining, extraction, purification, and processing, these quartz mineral resources are widely used in many key areas that constrain national security and economic and social development, such as petroleum geology, energy and chemical industry, glass manufacturing, refractory materials, new energy vehicles, integrated circuits, optical fiber communication, ceramic preparation, industrial building materials, optical devices, microelectronics manufacturing, semiconductor devices, and piezoelectric sensors.

[0005] To investigate the formation mechanisms and occurrence principles of common geological disasters deep within the Earth, such as volcanoes, earthquakes, and debris flows, geologists typically employ multi-faceted, large-cavity high-pressure equipment, including hydrothermal autoclaves, piston cylinder presses, and rotary shear friction testing machines, to conduct simulation experiments on the solubility, friction coefficient, shear stress, and other physical parameters of large-volume polycrystalline quartz polymers under high temperature and pressure conditions. Obtaining a large-sized polycrystalline quartz polymer experimental sample (46.58 mm (diameter) × 70.57 mm (height)) is a crucial step in simulating these physical properties under high temperature and pressure conditions. Geologists typically use natural quartz found in the field instead of polycrystalline quartz as experimental samples. However, natural quartz has many drawbacks, including low sample density, a large number of impurity minerals (such as framework silicate minerals, layered silicate minerals, carbonate minerals, oxide minerals, fluoride minerals, and metal sulfides of different compositions, including albite, potassium feldspar, biotite, muscovite, dolomite, calcite, rutile, fluorite, pyrite, and magnetite), large and unevenly distributed single crystal grains of the main minerals, difficulty in eliminating the preferred orientation of the crystal lattice, and significant anisotropy of the crystal axis. As a result, many different high-temperature and high-pressure mineral and rock property simulation teams around the world use natural quartz as the initial sample and employ multi-faceted large-cavity high-pressure equipment such as hydrothermal autoclaves, piston cylinder presses, and rotary shear friction testers. The experimental data on the physical properties of natural quartz under high-temperature and high-pressure conditions obtained show significant differences, making it difficult to widely apply these experimental results to the interpretation of the formation mechanisms and occurrence mechanisms of geological disasters such as volcanoes, earthquakes, and debris flows.

[0006] Compared with existing technologies, artificially synthesized island-shaped silicate mineral single crystal experimental samples can be prepared under high temperature and high pressure conditions using quasi-hydrostatic presses such as YJ-3000t and Kawai-1000t, as shown in patent {Dai Lidong and Hu Haiying. Chinese National Invention Patent: A method for preparing low-titanium dry forsterite single crystals under high temperature and high pressure conditions. Patent No.: ZL202111317925.5}. However, this method is limited to preparing island-shaped silicate mineral single crystal experimental samples rather than polycrystalline mineral aggregate samples. The obtained island-shaped silicate mineral single crystals have a particle size ranging from 100 micrometers to 425 micrometers, and the particle size distribution is uneven. The size of the obtained single crystal minerals is severely limited by the sample chamber volume. The cylindrical sample size of the high temperature and high pressure experimental product—single crystal island-shaped silicate minerals—obtained by this method does not exceed 6 mm (bottom diameter) × 6 mm (height). Therefore, the size of the artificially synthesized island-shaped silicate mineral samples cannot meet the requirements for simulating the physical properties of minerals and rocks under high temperature and high pressure conditions in large blocks. Although existing techniques, using quasi-hydrostatic presses such as the YJ-3000t and Kawai-1000t, can produce samples only a few millimeters in size, they are a relatively effective method for synthesizing single-crystal mineral samples under high temperature, high pressure, and quasi-hydrostatic conditions. However, when this method is applied to the synthesis of bulk polycrystalline quartz aggregate samples (e.g., with a diameter greater than 40 mm), significant asymmetric shrinkage inevitably occurs at the top and bottom of the quartz sample powder due to unidirectional compression during the high temperature, high pressure, and quasi-hydrostatic experiments. This results in numerous macroscopic voids and defects during the preparation of bulk polycrystalline mineral aggregate samples. These macroscopic voids and defects cause wrinkles or pores in the central part of the cross-section of the bulk polycrystalline quartz aggregate, ultimately making it easy for the sample to undergo severe porosity or aggregation along the center of the wrinkles or pores. This is the unavoidable shrinkage and porosity effect during the synthesis of bulk polycrystalline mineral aggregate samples under high temperature, high pressure, and quasi-hydrostatic conditions. The shrinkage and porosity effects of these polycrystalline quartz polymer samples lead to severe excessive deformation, resulting in numerous voids, folds, and cavities in the bulk polycrystalline quartz polymer samples. This significantly affects the preparation results of the bulk polycrystalline quartz polymer samples. Therefore, neither natural quartz nor small-sized (no more than 6 mm) quartz single crystal samples obtained in the laboratory can meet the minimum experimental sample size requirements for mineral and rock property simulation on multi-faceted, large-cavity high-pressure equipment such as hydrothermal autoclaves, piston cylinder presses, and rotary shear friction testing machines. To date, there is still no effective synthesis method.Therefore, it is particularly urgent to effectively synthesize a high-density, high-compactness, high-purity, and bulk polycrystalline quartz aggregate experimental sample that meets the needs of various high-temperature and high-pressure laboratory simulations in earth science research, especially for experimental simulation studies of the physical properties of bulk framework-structured dioxide mineral aggregates—polycrystalline quartz group minerals and rocks—under high-temperature and high-pressure conditions, such as solubility, friction coefficient, and shear stress. Summary of the Invention

[0007] The technical problem to be solved by this invention is to provide a method for preparing high-density and bulk polycrystalline quartz polymers under hot isostatic pressing, thereby filling the technical gap in the preparation of bulk experimental samples of high-density polycrystalline quartz polymers under high temperature and high pressure conditions. This method aims to obtain bulk high-density polycrystalline quartz polymer experimental samples, providing important experimental sample support for the experimental simulation study of the solubility, friction coefficient, shear stress, and other properties of bulk framework-structured oxide mineral polymers—polycrystalline quartz group minerals—under high temperature and high pressure conditions on multi-faceted large-cavity high-pressure equipment such as hydrothermal autoclaves, piston cylinder presses, and rotary shear friction testing machines.

[0008] The technical solution of this invention is:

[0009] A method for preparing high-density and bulk polycrystalline quartz polymers under hot isostatic pressing, comprising: compacting and sealing quartz sample powder to a vacuum degree of 10. –3 The sample was placed in a steel cladding with dimensions of 55.94 mm (outer diameter) × 88.77 mm (height) × 3 mm (wall thickness). The cladding was then placed inside the graphite furnace of a hot isostatic pressing (HIP) high-pressure vessel and sealed with a graphite cap. Using argon as the pressure transfer medium, a multi-gradient HIP method was employed, first increasing the pressure and then increasing the temperature, to raise the temperature inside the sample chamber to 940°C and the pressure to 114.1 MPa, which was maintained for 4.5 hours. A multi-gradient cooling and depressurization method was then used to lower the temperature inside the sample chamber to 180°C, and the pressure was reduced to 72.8 MPa. Finally, the pressure was released and the sample was cooled to room temperature to obtain a polycrystalline quartz polymer.

[0010] The preparation of the quartz sample powder includes:

[0011] Step 1: Select hexagonal prismatic quartz single crystal mineral particles with a minimum particle size of 8.9 mm and a maximum particle size of 13.3 mm as the initial sample;

[0012] Step 2: Place the selected quartz single crystal mineral particles on an ultrasonic cleaner, and use acetone, alcohol and deionized water as cleaning solutions in sequence for ultrasonic cleaning for 26 minutes.

[0013] Step 3: Select 330 grams of quartz single crystal particles that are complete in crystal form, colorless and transparent, with fresh surface and free of impurities.

[0014] Step 4: Place the quartz single crystal particles in a vacuum drying oven at 200 degrees Celsius and dry for at least 39 hours;

[0015] Step 5: Crush the dried quartz single crystal mineral particles into mineral single crystal particles with a particle size of less than 2 mm.

[0016] Step 6: Grind the mineral single crystal particles into quartz mineral powder with a particle size of 10.68 micrometers to 20.75 micrometers;

[0017] Step 7: Pack the quartz mineral powder into a paper sealed bag and dry it in a vacuum drying oven at 85 degrees Celsius for 9 days to obtain quartz sample powder.

[0018] The method for preparing the steel cladding includes: selecting a continuously cast slab of No. 20 low-carbon steel with a wall thickness of 3 mm as the initial raw material for the steel cladding sleeve, heating it to 200 °C, and then using a roughing mill and a finishing mill to cool it to a set temperature through laminar flow, and then coiling it into a steel strip coil by a coiler. This coil undergoes three rolling processes and multiple hot rolling processes including edge trimming to obtain a steel cladding sleeve with dimensions of 55.94 mm (outer diameter) × 88.77 mm (height) × 3 mm (wall thickness); selecting a continuously cast slab of No. 20 low-carbon steel with a wall thickness of 3 mm as the initial raw material for the steel cladding cap, and using the same multiple hot rolling process to prepare the upper and lower sealing caps of the steel cladding, and then welding the sleeve, upper sealing cap, and lower sealing cap together by high-temperature vacuum welding to prepare a complete steel cladding.

[0019] The quartz sample powder was compacted and sealed to a vacuum degree of 10. –3 The method for a steel cladding with dimensions of 55.94 mm (outer diameter) × 88.77 mm (height) × 3 mm (wall thickness) includes:

[0020] Step 9: First, vacuum weld the sleeve and lower sealing cap of the steel cladding. Then, place the quartz sample powder inside the steel cladding. After compaction, vacuuming, high-temperature degassing, and high-temperature vacuum welding, the quartz sample powder is compacted and sealed in a vacuum of 10... –3 The steel cladding of Pa was used for vacuuming for at least 75 hours, followed by high-temperature degassing at 400 °C.

[0021] The beneficial effects of this invention are:

[0022] This invention organically combines general geology, magmatic petrology, crystallography, dynamics of Earth's structural evolution, ore field tectonic geology, crystal defect chemistry, meteoritics and Earth's origin, engineering geology, optical mineralogy, isotope geochemistry, genetic mineralogy, mining geology, introduction to geophysics, rock mechanics, mineralogy, petrography, geochemistry, ore deposit geology, mineral resource geology, sedimentary petrology, metamorphic petrology, regional field geology, structural geology, stratigraphy, geochronology, and experimental petrology. With a background in Earth science disciplines such as geochemistry, ore genesis, rock rheology, geodynamics, hot isostatic pressing, hot isostatic powder metallurgy, seismology, igneous magmatism, high-pressure rheology, mineral physics, deep Earth science, high-pressure materials science, materials science, and high-pressure experimental mineralogy, this team uses an RD80×100‒2000–200 double 2000-type hot isostatic pressing equipment to prepare large-volume, highly dense polycrystalline quartz aggregate experimental samples under high temperature and high pressure conditions.

[0023] The initial raw material selected for this invention is gem-quality single-crystal quartz particles collected in the field, which are crushed into uniform mineral single-crystal powder. The powder is placed in a steel sheath and subjected to a series of processes including compaction, vacuuming, high-temperature degassing, high-temperature vacuum welding, argon filling, and furnace washing to ensure that the quartz sample powder is in a completely sealed environment protected by argon inert gas. The steel sheath containing the quartz sample powder is placed in the sample chamber of an RD80×100‒2000–200 double 2000 type hot isostatic pressing equipment, and sintered under high temperature and high pressure to form a large-volume, highly dense polycrystalline quartz aggregate. The prepared polycrystalline quartz aggregate sample can be widely used in the experimental simulation research of diagenesis and mineralization of mineral and rock physicochemical properties under high temperature and high pressure conditions.

[0024] The steel sheath used in the hot isostatic pressing (HIP) experiment of this invention has the following dimensions: 55.94 mm (outer diameter) × 88.77 mm (height) × 3 mm (wall thickness). This allows for the acquisition of large-sized polycrystalline quartz polymer samples with a diameter of up to 46.58 mm and a height of up to 70.57 mm. During the HIP experiment on the polycrystalline quartz polymer samples under high temperature and high pressure conditions, inert argon gas is used as the pressure transmission medium. By increasing the temperature and compressing the inert argon gas, uniform pressure and temperature are applied to the quartz sample powder in all directions, effectively avoiding the adverse effects of shrinkage cavities and porosity during the HIP experiment. The inert argon gas ensures complete isolation between the quartz sample powder and air within the sample chamber, effectively preventing redox reactions between the quartz sample powder and air during the HIP experiment. Furthermore, this invention avoids the traditional high-pressure chemical reaction method, which may introduce excessive chemical reagents during the preparation of polycrystalline quartz polymer samples, potentially leading to the introduction of impurity ions.

[0025] This invention employs a multi-gradient hot isostatic pressing (HIP) process, which first increases pressure and then increases temperature. The resulting polycrystalline quartz polymer experimental samples exhibit excellent physicochemical properties, including fine crystal size, high density, and high purity. This breakthrough overcomes the technical bottleneck of synthesizing large-volume experimental samples of high-density polycrystalline quartz polymers. Furthermore, this multi-gradient HIP process is not limited by the shape or size of the sample and can produce complex polycrystalline mineral samples with irregular shapes. Compared to existing technologies that use quasi-hydrostatic presses such as the YJ-3000t and Kawai-1000t to prepare artificially synthesized island-shaped silicate mineral single crystals under high temperature and high pressure, this invention, with its multi-gradient HIP process, can obtain polycrystalline quartz polymer experimental samples with near-theoretical density and extremely high sample strength.

[0026] This invention, based on an RD80×100‒2000–200 dual 2000-type hot isostatic pressing (HIP) device, employs a multi-gradient HIP molding process involving first increasing pressure and then increasing temperature. For the first time, it yields large-volume, uniformly distributed, high-density, highly compact, and high-strength polycrystalline quartz aggregate experimental samples under conditions of 114.1 MPa and 940 °C. These samples can be widely applied to experimental simulations of the solubility, friction coefficient, and shear stress properties of large-volume framework-structured oxide mineral aggregates—polycrystalline quartz group mineral rocks—on high-pressure equipment with multiple large cavities, such as hydrothermal autoclaves, piston cylinder presses, and rotary shear friction testing machines. This provides crucial experimental sample support for systematically exploring the formation mechanisms and occurrence principles of common geological disasters such as deep-earth volcanoes, earthquakes, and debris flows. Attached Figure Description

[0027] Figure 1 To utilize the RD80×100‒2000–200 double 2000 type hot isostatic pressing equipment, and adopt a multi-gradient hot isostatic pressing molding process of first increasing pressure and then increasing temperature, the temperature and pressure in the sample chamber during the preparation of polycrystalline quartz polymer are shown in the curves of temperature and pressure change over time.

[0028] Figure 2 To obtain fine-grained quartz sample powder by crushing and grinding with the help of a jaw crusher (model: BB 200) and a high-efficiency Retsch disc vibratory mill (model: RS200), optical microscopic observation results of quartz samples before hot isostatic pressing experiments were obtained using a high-precision Olympus SZX16 research-grade stereomicroscopic imaging platform.

[0029] Figure 3 This document presents the optical microscopic observation results of the surface morphology and particle size distribution of polycrystalline quartz polymer samples obtained from hot isostatic pressing experiments at 114.1 MPa and 940 °C using the high-precision Olympus SZX16 research-grade stereomicroscopy platform. Detailed Implementation

[0030] A method for preparing high-density and bulk polycrystalline quartz polymers under hot isostatic pressing, comprising:

[0031] Step 1: Use hexagonal prismatic quartz single crystal mineral particles as the initial sample; use a high-precision Olympus SZX16 research-grade stereomicroscopy imaging platform to accurately measure the particle size of the initial sample. The smallest particle size of the quartz single crystal is 8.9 mm and the largest particle size is 13.3 mm. If the mineral grain size of the quartz single crystal is too large, only a low-magnification, high-precision Olympus SZX16 research-grade stereomicroscopy platform can be used for sample selection, making it difficult to accurately identify high-purity quartz single crystals that do not contain other symbiotic / associated minerals or impurity minerals. If the mineral grain size of the quartz single crystal is too small, it is difficult to effectively separate the quartz single crystal from framework silicate minerals, layered silicate minerals, carbonate minerals, oxide minerals, fluoride minerals, and metal sulfides of different compositions, such as albite, potassium feldspar, biotite, muscovite, dolomite, calcite, rutile, fluorite, pyrite, and magnetite. Furthermore, this invention requires the selection of mineral single crystals with a relatively large weight, which will consume a lot of time and manpower.

[0032] Step 2: Place the selected quartz single crystal particles on an ultrasonic cleaner and use acetone, alcohol and deionized water as cleaning solutions in sequence for ultrasonic cleaning for 26 minutes to remove impurities from the sample surface.

[0033] Step 3: Using a high-magnification, high-precision Olympus SZX16 research-grade stereomicroscopic imaging platform, carefully select 330 grams of quartz single crystal particles with complete crystal form, colorless transparency, fresh surface, and no other impurity minerals to ensure that the initial sample quartz single crystal has high purity before the hot isostatic pressing experiment under high temperature and high pressure conditions.

[0034] Step 4: Place the carefully selected quartz single crystal particles in a vacuum drying oven at 200 degrees Celsius for at least 39 hours to completely remove adsorbed water from the sample surface. If the temperature is too low, a certain amount of adsorbed water may adhere to the surface of the quartz crystals, making it difficult to accurately weigh the initial sample quartz single crystal particles during further grinding. If the temperature is too high, it may cause a structural phase transformation reaction in the quartz single crystals, ultimately severely affecting the preparation effect of the hot isostatic pressing experimental sample under high temperature and high pressure conditions.

[0035] Step 5: Place the initial sample of quartz single crystal particles on a jaw crusher (model: BB 200), set the instrument's drive power to 1.5 kW, and use a crushing time of 7 minutes to crush the natural quartz single crystal into mineral single crystal particles with a particle size of less than 2 mm. The purpose is to fully crush the sample to obtain quartz single crystal particles with a medium particle size (less than 2 mm).

[0036] Step 6: Place the sample on a high-efficiency Retsch disc vibratory mill (model: RS200), using a high-speed mode of 1350 rpm and setting the instrument's drive power to 1.5 kW. Grind the mineral single crystal particles into fine-grained quartz mineral powder with a particle size of 10.68 μm to 20.75 μm (see...). Figure 2 The amount of single-crystal quartz sample ground in a single cycle is 100 grams, and the grinding time is 5 minutes. Quartz sample powder in this particle size range has a large specific surface area (surface area per unit weight of mineral powder), which significantly increases the contact area between particles due to pressure and temperature. This is more conducive to forming a strong bonding force between quartz sample powder particles during the hot isostatic pressing experiment of this invention, thereby greatly improving the compactness and density of the prepared fine-grained polycrystalline quartz polymer sample.

[0037] Step 7: Considering that the quartz sample powder with a relatively fine particle size is easy to absorb water in the air, put it into a paper sealed bag and place it in a vacuum drying oven at 85 degrees Celsius for 9 days to completely remove the adsorbed water on the surface of the sample powder.

[0038] Step 8: In the process of preparing polycrystalline quartz polymer samples using an RD80×100‒2000–200 double 2000 type hot isostatic pressing (HIP) equipment, a sample steel sheath was prepared using low-carbon steel of No. 20 steel. No. 20 steel refers to steel with a carbon content between 0.17% and 0.23%. The low-carbon steel (No. 20 steel) sheath selected in this case has the following main superior properties: (1) The low-carbon steel (No. 20 steel) sheath does not react with the quartz sample powder, avoiding contamination of the sample during the HIP experiment and directly affecting the preparation effect; (2) The low-carbon steel (No. 20 steel) sheath can withstand the temperature of 940 °C and the pressure of 114.1 required for the preparation of polycrystalline quartz polymer samples under the HIP conditions of this invention. MPa; (3) The steel sheath material of low carbon steel (20 steel) has good air tightness, which ensures that the quartz sample powder will not leak under high temperature, high pressure and argon gas pressure transmission medium conditions, and can also ensure the sealing of the steel sheath and the sealing of the weld during the vacuum exhaust process. All these properties are very reliable; (4) The steel sheath of low carbon steel (20 steel) also has excellent properties such as relatively easy edge rolling, cutting, processing, deformation and welding performance.

[0039] This invention selects a continuously cast slab of No. 20 low-carbon steel with a wall thickness of 3 mm as the initial raw material for the steel cladding sleeve. After heating it to 200 °C, it is cooled to the set temperature by laminar flow using a roughing mill and a finishing mill. It is then rolled into a steel strip coil by a coiler, and then undergoes multiple hot rolling processes including three rolling and edge trimming to finally obtain a hot isostatic pressing test steel cladding sleeve for quartz sample powder with dimensions of 55.94 mm (outer diameter) × 88.77 mm (height) × 3 mm (wall thickness).

[0040] Similarly, a continuously cast slab of No. 20 low-carbon steel with a wall thickness of 3 mm was selected as the initial raw material for the steel cladding cover. The same hot rolling process was used to prepare the upper and lower sealing covers of the steel cladding. The sleeve, upper and lower sealing covers were welded together by high-temperature vacuum welding to prepare a complete steel cladding for hot isostatic pressing of quartz sample powder.

[0041] Step 9: First, vacuum weld the sleeve and lower sealing cap of the steel cladding. Then, place the dried quartz sample powder inside the steel cladding. After a series of key steps, including compaction, vacuuming, high-temperature degassing, and high-temperature vacuum welding, the sample powder is completely sealed in a vacuum of 10... –3 Pa is in the steel ladle sleeve.

[0042] Achieving such a low vacuum level within the steel-clad cavity requires at least 75 hours of evacuation, while simultaneously degassing the sample at 400 °C to ensure the quartz powder is completely in a sealed vacuum environment and that all moisture is removed. The quartz powder sealed within the steel cladding must be thoroughly compacted. –3 The series of processes, including extremely low vacuum, 400°C high-temperature degassing, and high-temperature vacuum welding, are mainly aimed at: (1) ensuring that the quartz sample powder is fully compacted, which can ensure that enough quartz sample powder is sealed in the steel sleeve, which will help increase the density of the hot isostatic pressing product polycrystalline quartz polymer, thereby greatly improving the preparation effect of the final product bulk polycrystalline quartz polymer sample; (2) ensuring that the quartz sample powder is fully compacted, which can ensure the filling amount of quartz sample powder sealed in the steel sleeve, which will help enhance the compactness between quartz sample powder particles, effectively avoid the sample from deforming too much during the hot isostatic pressing experiment, thereby greatly improving the compactness of the final product bulk polycrystalline quartz polymer sample; (3) maintaining 10 –3The extremely low vacuum of Pa ensures that the steel sheath is easily deformed under high temperature and high pressure, thereby uniformly transmitting the high pressure borne by the steel sheath to the quartz sample powder inside it; (4) Under the condition of 400 °C, the quartz sample powder is degassed at high temperature, completely removing the water vapor that may exist in the sample powder; (5) The steel sheath is welded by high temperature vacuum, which effectively isolates the welding head from direct contact with air, and the high temperature oxidation of the metal welding point can be completely avoided, which will greatly enhance the sealing performance of the steel sheath.

[0043] Step 10: Carefully place the steel sleeve containing the quartz sample powder into the graphite furnace cylinder of the high-pressure vessel of the hot isostatic pressing (HIP) equipment, and cover it with the graphite sealing cap. This invention uses an RD80×100‒2000–200 double 2000-type HIP equipment to densify the quartz sample powder under high temperature and high pressure conditions. The graphite furnace cylinder is the core component of this equipment and also the heating element that achieves the extremely high sample chamber temperature of 2000 degrees Celsius.

[0044] Step 11: Turn on the main power switch, dedicated computer automatic program, exhaust fan and argon concentration detection alarm of the RD80×100‒2000–200 dual 2000 type hot isostatic pressing equipment in sequence. Because the hot isostatic pressing (HIP) equipment operates at a power of 30 kW / hour, it is an ultra-high-power, high-temperature, and high-pressure instrument. Therefore, to ensure the safety of the experimental operators, the main power switch must be kept off when the equipment is not in operation. To ensure automatic control and arbitrary adjustment of temperature and pressure during HIP experiments, a dedicated computer-controlled software program has been developed for this instrument. A dual-pipeline high-power exhaust system is used to prevent leakage of the inert argon gas pressure transmission medium during the HIP experiment of polycrystalline quartz polymer samples under high temperature and pressure. Excessive argon concentration in the operating space could lead to asphyxiation for the operators. A high-sensitivity laboratory-specific argon concentration monitoring alarm is used. Its main purpose is to monitor the argon concentration in the sealed laboratory space during the operation of the HIP equipment in real time. Abnormal changes in argon concentration in the sealed space can also determine the operating status of high-pressure argon in the pipes and circuits of the high-pressure device, ensuring the absolute safety of the operators during HIP experiments.

[0045] This invention uses argon as an inert gas as the pressure transfer medium. Argon is chosen because it is a colorless, tasteless, odorless, non-toxic, chemically stable, and thermally conductive inert gas. Compared with nitrogen, argon has more stable chemical properties and can completely maintain the chemical composition and process performance of the prepared material, thereby greatly improving the repeatability of the preparation molding process and the reliability of the product performance. However, in the hot isostatic pressing experiment, the main drawbacks of choosing nitrogen as the pressure transfer medium are as follows: (1) Under high temperature and high pressure conditions, nitrogen inevitably reacts with various metals or alloys, especially for samples containing multiple active metals such as titanium, aluminum, and zirconium. The samples will be nitrided, and a nitride layer will be formed on the surface of the sample, which will seriously change the mechanical properties and chemical composition of the prepared product; (2) When preparing oxide ceramics (such as alumina, zirconium oxide, etc.) or many other functional ceramics through hot isostatic pressing, if nitrogen is chosen as the pressure transfer medium, nitrogen can easily enter the crystal in the form of defects or vacancies during the high temperature and high pressure experiment. (3) Nitrogen used in industrial applications often contains trace amounts of water, carbon dioxide and oxygen. If the purification is incomplete or incomplete, the oxidation, denitrification and decarbonization reactions of the sample will be accelerated during the high temperature and high pressure experiment, which will seriously affect the physicochemical properties of the sample product. (4) Although nitrogen has a lower cost advantage compared to argon, for high-value-added hot isostatic pressing workpieces such as aerospace parts and medical implants, the aviation safety cost, health cost and scrap loss cost caused by the nitriding reaction are far greater than the gas pressure transmission medium cost of the hot isostatic pressing experiment itself. Compared with hydrogen, argon can be mixed with oxygen in the air in any proportion, and hydrogen may also cause an explosion hazard under high temperature and high pressure. Compared with other common inert gases such as helium and neon, argon has unique advantages such as good thermal conductivity and lower price.

[0046] This invention uses high-purity argon gas with a purity of 99.999% as the pressure transmission medium. Its main purpose is to: (1) inject argon gas into the cylinder through a high-pressure pipeline with the help of a booster pump, and then heat it in the cylinder by a high-temperature resistant graphite furnace. The isotropic temperature and pressure will be uniformly transmitted to the quartz sample powder pressing parts to complete the hot isostatic pressing molding experiment; (2) Argon gas has excellent thermal conductivity, so the temperature distribution in the furnace is relatively uniform; (3) Selecting high-purity inert gas argon gas isolates other gases in the environment and can completely avoid the steel cladding from being oxidized during the hot isostatic pressing experiment; (4) Selecting high-purity inert gas argon gas plays an important protective role for the core component of the RD80×100‒2000–200 double two thousand type hot isostatic pressing equipment - the graphite heating element, and extends its service life.

[0047] Step 12: In this invention, argon is selected as the pressure transmission medium. During the preparation of polycrystalline quartz polymers on an RD80×100‒2000–200 dual 2000-type hot isostatic pressing (HIP) device, a multi-gradient HIP molding process of first increasing pressure and then increasing temperature is employed. Given that the initial material of this invention is a mineral powder that is difficult to mold, the use of argon as an inert gas pressure transmission medium and the selection of a multi-gradient HIP molding process of first increasing pressure and then increasing temperature can greatly improve the density and compactness of bulk polycrystalline quartz polymer products.

[0048] This invention employs a multi-gradient hot isostatic pressing (HIP) process, involving prior pressurization followed by heating, to synthesize bulk experimental samples of high-density, high-compactness, and high-purity polycrystalline quartz polymers. The target pressure and temperature for the HIP experiment are 114.1 MPa and 940 °C, respectively. If the selected target pressure and temperature are too low, the steel sheath used to seal the quartz sample powder during the HIP experiment will not be sufficiently compressed and effectively deformed, making it difficult to fully compact and sinter the sample. This severely affects the preparation of the experimental product—a bulk, high-density, and high-compact polycrystalline quartz polymer sample. Conversely, if the selected target pressure and temperature are too high, the framework-structured dioxide mineral polymer—quartz sample—will undergo a structural phase transformation reaction during the HIP experiment, which will have an extremely adverse effect on the prepared polycrystalline quartz polymer product.

[0049] This invention uses argon gas as the pressure transmission medium. The target pressure and temperature values ​​are obtained by inputting argon gas into a gas cylinder. Therefore, before the hot isostatic pressing (HIP) experiment of quartz sample powder, it is necessary to accurately calculate the amount of argon gas required for the target pressure and temperature values. Through multiple repeatable low-temperature high-pressure empty furnace HIP experiments, high-temperature low-pressure empty furnace HIP experiments, and high-temperature high-pressure empty furnace HIP experiments of quartz sample powder, precise temperature and pressure calibration of the quartz sample cavity is performed. Finally, based on the RD80×100‒2000–200 dual 2000-type HIP equipment, high-purity inert argon gas is selected as the pressure transmission medium to complete the sample preparation for a single large-volume polycrystalline quartz polymer HIP experiment. The formula for calculating the amount of argon gas consumed is as follows:

[0050] (1)

[0051] (2)

[0052] In the formula: parameter P target The target pressure for preparing polycrystalline quartz polymer samples under hot isostatic pressing is based on the target temperature (T) of the hot isostatic pressing experiment. target ) Perform the calculation; parameter P bottleThe parameter t represents the internal pressure of the inert gas argon in the cylinder; the parameter t represents the number of 40-liter large-volume and high-purity inert gas argon (purity: 99.999%) cylinders required to complete a single hot isostatic pressing experiment on a polycrystalline quartz polymer sample under high temperature and high pressure conditions.

[0053] Step 13, vacuuming, filling with argon gas and cleaning the furnace, the purpose of which is to completely remove the air from the sample chamber. The specific operation steps are as follows: (1) Vacuuming: turn on the gas vacuum pump control switch to evacuate the air in the high-pressure sample chamber that is directly connected to the gas vacuum pump. When the detection value of the vacuum degree instrument digital display reaches 10 –4 (1) When the pressure reaches 15 MPa, turn off the gas vacuum pump; (2) Fill the cylinder directly connected to the high-purity inert gas argon with argon gas, and stop filling the pressure medium when the pressure in the sample chamber reaches 15 MPa; (3) Clean the furnace: turn on the gas vacuum pump and pump the vacuum in the sample chamber to 10 MPa. –4 MPa, repeated evacuation and filling three times, thus completely removing all the air from the sample chamber.

[0054] Step 14: Pre-pressurization of the sample chamber. Specific operation steps: (1) Calculate the amount of inert argon gas according to Formula 1 and Formula 2. In order to achieve the target pressure of 114.1 MPa and the target temperature of 940 °C, at least 4 argon cylinders with an internal pressure of 15 MPa are required; (2) Fill the argon cylinders with an internal pressure of 15 MPa evenly into the high-pressure pressurization tank of the hot isostatic pressing equipment. Then, through the high-pressure delivery pipeline, fill the cylinder with argon gas from the high-pressure pressurization tank, so that the pressure of the high-pressure pressurization tank and the pressure in the cylinder are balanced; (3) Turn on the diaphragm compressor and pump all the remaining argon gas in the high-pressure tank into the quartz sample chamber of the cylinder, so that the pre-pressurization of the sample chamber in the cylinder is pressurized to 58.7 MPa.

[0055] Step 15: Multi-gradient cylinder block heating and pressurization (see...) Figure 1Taking into account the target pressure and temperature for preparing polycrystalline quartz polymer samples in hot isostatic pressing (HIP), as well as the safety, reliability, and durability of the graphite heating element itself, a precise and automatic multi-gradient cylinder heating and pressurization HIP procedure was developed. The specific steps are as follows: Within the temperature range of room temperature–600 °C, a heating rate of 18.04 °C / min and a pressurization rate of 1.03 MPa / min were used to raise the temperature in the cylinder sample chamber to 600 °C and the pressure to 89.6 MPa; within the medium temperature range of 600 °C–860 °C, a heating rate of 13 °C / min and a pressurization rate of 0.85 MPa / min were used to raise the temperature in the cylinder sample chamber to 860 °C and the pressure to 106.5 MPa, maintaining this temperature and pressure for 1.0 hour to ensure that the polycrystalline framework structure of the oxide minerals was fully compacted and cemented; after maintaining this temperature and pressure for 1.0 hour, the temperature and pressure were then maintained in the high temperature range of 860 °C–940 °C. Within a temperature range of °C, the temperature inside the sample chamber was raised to 940 °C and 114.1 MPa using a heating rate of 5.33 °C / min and a pressurization rate of 0.51 MPa / min. As the temperature increased, the argon gas inside the sealed cylinder expanded dramatically, while the cylinder volume remained constant, meaning the argon gas volume was uniformly compressed, resulting in uniform high pressure. Ultimately, the pressure inside the sample chamber was maintained at 114.1 MPa. The quartz sample powder was then held at 114.1 MPa and 940 °C for 4.5 hours. Quartz, an important end-member component of silicate minerals and a major rock-forming mineral, is an oxide mineral widely distributed in various spheres of the deep Earth. It is exposed in various geological formations, including igneous, sedimentary, and metamorphic rocks. It exhibits a complex crystal system with typical P1–P2 space groups and low symmetry, consisting of trigonal–orthorhombic–hexagonal crystals, as well as relatively complex crystal morphology, distinct preferred lattice orientations, and anisotropic physicochemical properties.

[0056] This invention employs a multi-gradient hot isostatic pressing (HIP) process, involving prior pressurization followed by heating, to prepare polycrystalline quartz polymer samples. During the pressurization and heating process, the samples are held at 860 °C and 940 °C for 1.0 hour and 4.5 hours respectively, ensuring sufficiently long stepped holding times. If the holding time is too short, it is difficult to form strong bonding forces between the low-symmetry and diverse crystal morphologies of quartz mineral particles, and it is also difficult to overcome the influence of many unfavorable factors such as the preferred orientation and anisotropy of the quartz lattice, thus affecting the density and strength of the final bulk polycrystalline quartz polymer sample. Conversely, if the holding time is too long, although a highly dense and strong polycrystalline quartz polymer can be obtained, the final bulk polycrystalline quartz polymer sample will experience particle growth, uneven particle distribution, and recrystallization under prolonged high temperature and high pressure, severely affecting the preparation effect and resulting in higher experimental costs.

[0057] Step 16: Multi-gradient cylinder cooling and depressurization. After the quartz sample powder was kept at 114.1 MPa and 940 °C for 4.5 hours, the temperature inside the sample chamber was reduced to 860 °C and the pressure to 109.3 MPa at a cooling rate of 5.33 °C / min and a depressurization rate of 0.32 MPa / min, and kept at the same temperature and pressure for 1.0 hour. After 1.0 hour of constant temperature and pressure, the temperature inside the sample chamber was reduced to 180 °C and the pressure to 72.8 MPa at a slower cooling rate of 14.78 °C / min and a slower depressurization rate of 0.79 MPa / min. Compared to the pressurization process, a slower cooling and depressurization rate was used mainly because if the cooling and depressurization rates were too fast, the internal stress of the steel sheath would not be fully released, leading to the fragmentation and damage of the large-volume polycrystalline quartz polymer product, which would seriously affect the preparation effect.

[0058] This invention selects a sample chamber cylinder temperature of 180 °C because this temperature falls within the safe temperature range (160 °C–180 °C) that the RD80×100‒2000–200 dual 2000 type hot isostatic pressing (HIP) equipment can withstand direct pressure relief. If the sample chamber cylinder temperature exceeds 180 °C, the resulting excessive internal pressure in the sample chamber could easily damage the graphite heating furnace and may also cause a safety accident with the HIP equipment. If the sample chamber cylinder temperature is below 160 °C, the resulting excessively low internal pressure in the sample chamber makes it difficult to ensure that the argon inert pressure-transmitting medium sealed within the sample chamber is completely expelled during the pressure relief process in the HIP experiment.

[0059] Step 17, Depressurization. First, allow the argon gas in the hot isostatic pressing (HIP) cylinder to flow freely back to the high-pressure pressurization tank through the pipeline. Then, when the cylinder pressure and the high-pressure pressurization tank pressure reach equilibrium, turn on the diaphragm compressor to vent the gas in the cylinder and discharge all residual gas through the pipeline.

[0060] Step 18, Cooling. After all the inert argon gas in the pipeline has been completely removed, the cooling system connected to the furnace body of the hot isostatic pressing equipment continues to be turned on, and the natural cooling program is started to reduce the temperature inside the furnace from 180 °C to room temperature (~25 °C).

[0061] Step 19: Set the control program for the hot isostatic pressing (HIP) equipment, open the furnace chamber, carefully remove the polycrystalline quartz polymer steel-clad workpiece sealed after the HIP experiment, and accurately measure the dimensions of the steel cladding after the HIP forming experiment: 52.58 mm (outer diameter) × 80.57 mm (height). Compare the volume of the steel cladding before the HIP experiment and calculate the volume shrinkage rate (η) of the steel cladding before and after the HIP experiment. 钢包套 Its calculation formula can be expressed as: η 钢包套 =(V 实验前钢包套 –V 实验后钢包套 ) / V 实验前钢包套 The shrinkage rate (η × 100%) is 19.81%. This invention exhibits such a large volumetric shrinkage rate (η × 100%) for the steel sheath. 钢包套 =19.81%), confirming that the steel cladding used to seal and encapsulate the quartz sample powder underwent sufficient compression and effective deformation during the hot isostatic pressing experiment.

[0062] Step 20: Using a high-speed diamond saw blade cutter with a 1.0 mm thick diamond saw blade, the polycrystalline quartz polymer sample was carefully peeled from the steel ladle. The weight of the sample after the experiment was accurately measured to be 329 grams, and the weight of the steel ladle was 500 grams. This shows that the weight of the quartz sample remained essentially unchanged before and after the multi-gradient hot isostatic pressing (HIP) experiment, which involved increasing pressure followed by increasing temperature. Further precise measurements were taken of the dimensions of the polycrystalline quartz polymer sample obtained after the HIP experiment: 46.58 mm (diameter) × 70.57 mm (height). Comparing this to the initial volume of quartz powder encapsulated in the steel ladle before the HIP experiment, the volume shrinkage rate (η) of the sample before and after the HIP experiment was calculated. 石英 Its calculation formula can be expressed as: η 石英 =(V 实验前石英 –V 实验后石英 ) / V 实验前石英 The volume shrinkage rate (η × 100%) is 22.06%. This invention achieves such a large volume shrinkage rate (η) for quartz sample powder. 石英 =22.06%), confirming that during the hot isostatic pressing experiment, the quartz sample powder placed in the steel cladding was fully compacted and sintered under high temperature and high pressure conditions.

[0063] This invention utilizes an RD80×100‒2000–200 dual 2000-type hot isostatic pressing (HIP) apparatus to synthesize a polycrystalline quartz polymer from the initial material—a single-phase quartz single crystal—which is then crushed into medium-sized quartz single crystal particles, ground into fine quartz powder, and finally synthesized into the final product. Employing a multi-gradient HIP process that first increases pressure and then increases temperature, high-density, high-compactness, high-purity, and bulk polycrystalline quartz polymers are prepared. No other impurity phases are introduced during the entire preparation process, and the purity of the resulting polycrystalline quartz polymer samples can reach 100%.

[0064] Under epoxy resin embedding protection, a representative sample (17 mm × 17 mm cross-section) was cut from the polycrystalline quartz polymer workpiece, a product of the hot isostatic pressing experiment. The sample underwent epoxy resin embedding protection, cutting, grinding, and surface polishing. Using a high-precision Olympus SZX16 research-grade stereomicroscopic imaging platform, the surface morphology and particle size distribution characteristics of the polycrystalline quartz polymer sample were tested. The test results are shown in (see...). Figure 3 The polycrystalline quartz polymer exhibits clear grain boundary continuity, with minimal differences in the proportion of sample particles of different sizes, demonstrating a distinctly uniform particle size distribution. This invention utilizes a fully sealed steel sheath, inert argon gas pressure transmission medium, and a consistently closed vacuum environment for the sample powder during the hot isostatic pressing (HIP) experiment. This effectively isolates the sample from gases such as nitrogen, oxygen, and water vapor, thus achieving uniform particle distribution, no particle growth, and no recrystallization in the polycrystalline quartz polymer. Compared to existing technologies that use quasi-hydrostatic presses such as the YJ-3000t and Kawai-1000t to synthesize island-shaped silicate mineral single crystals under high temperature and high pressure, this invention employs a multi-gradient HIP process that first increases pressure and then increases temperature, effectively overcoming numerous drawbacks of polycrystalline quartz polymer products, such as particle growth, uneven particle distribution, and recrystallization.

[0065] High-resolution scanning electron microscopy was used to observe the microstructure of polycrystalline quartz polymer samples obtained from hot isostatic pressing experiments, and precise density tests were performed. The obtained polycrystalline quartz polymers had a density as high as 99.8%, exhibiting extremely high compactness. In the hot isostatic pressing (HIP) experiment, the present invention improves the following specific experimental scheme to ensure the acquisition of highly dense polycrystalline quartz polymer samples: (1) a higher pre-pressurization pressure (58.7 MPa); (2) a multi-gradient gradually decreasing cylinder heating mode, namely, in the low-temperature zone of the HIP experiment: room temperature–600 °C, the heating rate is 18.04 °C / min; in the medium-temperature zone: 600 °C–860 °C, the heating rate is 13 °C / min; in the high-temperature zone: 860 °C–940 °C, the heating rate is 5.33 °C / min; (3) a multi-gradient gradually decreasing cylinder pressure mode, namely, in the low-pressure zone of the HIP experiment: 58.7 MPa–89.6 MPa, the pressure rate is 1.03 MPa / min; in the medium-pressure zone: 89.6 MPa–106.5 MPa… Under pressure of MPa, the pressurization rate is 0.85 MPa / min; under high pressure: 106.5 MPa–114.1 MPa, the pressurization rate is 0.51 MPa / min; (4) a multi-gradient, slower cylinder cooling mode, that is, under high temperature: 940 °C–860 °C in the hot isostatic pressing experiment, the cooling rate is 5.33 °C / min; under medium and low temperature: 860 °C–180 °C, the cooling rate is 14.78 °C / min; (5) a multi-gradient, slower cylinder depressurization mode, that is, under high pressure: 114.1 MPa–109.3 MPa in the hot isostatic pressing experiment, the depressurization rate is 0.32 MPa / min; under medium and low pressure: 109.3 MPa–72.8 MPa, the depressurization rate is 0.79 MPa / min. MPa / min; (6) Multi-gradient cylinder constant temperature and pressure mode, that is, when the temperature and pressure rise during the hot isostatic pressing experiment, the constant temperature and pressure is maintained for 1.0 hours at 860 °C and 106.5 MPa; at the highest temperature (940 °C) and the highest pressure (114.1 MPa), the constant temperature and pressure is maintained for a sufficiently long time of 4.5 hours; when the temperature drops to 860 °C and the pressure is 109.3 MPa, the constant temperature and pressure is maintained for 1.0 hours.All these optimized and improved hot isostatic pressing (HIP) experimental schemes can promote sufficient diffusion and particle aggregation between quartz sample powders during HIP, eliminate the adverse effects of dendritic formation between sample powders, and thus form a uniform equiaxed grain structure; they can also promote the uniform isotropic temperature and pressure transmission during HIP, prevent the occurrence of local weaknesses or cracks, and thus greatly improve the compactness of the polycrystalline quartz polymer sample produced by HIP. In addition, this invention applies a higher temperature (940 °C), a higher pressure (114.1 MPa), and a sufficiently long heat and pressure holding time (4.5 hours) to promote the formation of good bonding force between the particles of the quartz sample powder, thereby greatly improving the density and strength of the polycrystalline quartz polymer sample produced by hot isostatic pressing. It also effectively overcomes the unavoidable temperature gradient, pressure gradient, and many adverse factors such as pores, voids, cracks, and healing defects in the experimental products produced by the existing technology that uses quasi-hydrostatic presses such as YJ-3000t and Kawai-1000t to synthesize island silicate mineral single crystals.

[0066] The Archimedes method using organically combined deionized water and the water intrusion method for porous and complex structures were employed to accurately measure the density of polycrystalline quartz polymer samples obtained from hot isostatic pressing experiments. The measured density of the polycrystalline quartz polymer was 2.65 g / cm³. 3 This density value falls exactly within the theoretical density of 2.53 g / cm³ for naturally collected quartz, as measured by geologists. 3 –2.66 g / cm 3Within the specified range, the obtained bulk polycrystalline quartz polymer samples exhibited extremely high density. The achievement of such high-density polycrystalline quartz polymer products is highly related to the optimized molding process employed during this hot isostatic pressing experiment, including quartz sample powder pretreatment, selection of No. 20 steel sample cladding, a reasonable cooling and depressurization hot isostatic pressing process, and high-temperature degassing at 400 °C. The quartz sample powder raw material pretreatment involves fine-grained quartz mineral powder with a particle size of 10.68 to 20.75 micrometers. Quartz within this particle size range has a large specific surface area, significantly increasing the contact area between sample particles. This promotes stronger bonding and greatly enhances the density of the prepared polycrystalline quartz polymer sample. A 3 mm thick 20# low-carbon steel continuous casting slab serves as the steel cladding, possessing excellent physical properties such as low strength, low hardness, high plasticity, and good toughness. This allows the high pressure borne by the steel cladding to be evenly transferred to the quartz sample powder enclosed within, further increasing the density of the prepared polycrystalline quartz polymer sample. An optimized and improved cooling and depressurization hot isostatic pressing process is employed, particularly using a slower, multi-gradient cylinder depressurization mode (pressurization rate: 0.51 MPa / min – 1.03 MPa / min; depressurization rate: 0.32 MPa / min – 0.79 MPa / min). (MPa / min) ensures that the internal stress of large-volume polycrystalline quartz polymer workpieces is fully released, effectively overcoming the adverse effects of delamination, cracks, and fissures in the sample product, and greatly improving the density of the polycrystalline quartz polymer sample. A high-temperature degassing optimization molding process at 400 °C is used, sealing the quartz sample powder in a steel sleeve and performing high-temperature vacuum degassing at 400 °C to minimize gas residue, thereby obtaining polycrystalline quartz polymer experimental samples with a very uniform density distribution under hot isostatic pressing. In contrast, existing technologies, such as the synthesis of island silicate mineral single crystals using quasi-hydrostatic presses like the YJ-3000t and Kawai-1000t, inevitably generate internal friction due to the unidirectional pressing, leading to uneven density distribution and delamination problems in the experimental product.

Claims

1. A method for preparing high-density and bulk polycrystalline quartz polymers under hot isostatic pressing, characterized in that: The method includes: compacting and sealing the quartz sample powder to a vacuum degree of 10. –3 The sample was placed in a steel cladding with dimensions of 55.94 mm (outer diameter) × 88.77 mm (height) × 3 mm (wall thickness). The cladding was then placed inside the graphite furnace of a hot isostatic pressing (HIP) high-pressure vessel and sealed with a graphite cap. Using argon as the pressure transfer medium, a multi-gradient HIP method was employed, first increasing the pressure and then increasing the temperature, to raise the temperature inside the sample chamber to 940 °C and the pressure to 114.1 MPa, which was maintained for 4.5 hours. A multi-gradient cooling and depressurization method was then used to lower the temperature inside the sample chamber to 180 °C, and the pressure was reduced to 72.8 MPa. Finally, the pressure was released and the sample was cooled to room temperature to obtain a polycrystalline quartz polymer.

2. The method for preparing high-density and bulk polycrystalline quartz polymers under hot isostatic pressing according to claim 1, characterized in that: The preparation of the quartz sample powder includes: Step 1: Select hexagonal prismatic quartz single crystal mineral particles with a minimum particle size of 8.9 mm and a maximum particle size of 13.3 mm as the initial sample; Step 2: Place the selected quartz single crystal mineral particles on an ultrasonic cleaner, and use acetone, alcohol and deionized water as cleaning solutions in sequence for ultrasonic cleaning for 26 minutes. Step 3: Select 330 grams of quartz single crystal particles that are complete in crystal form, colorless and transparent, with fresh surface and free of impurities. Step 4: Place the quartz single crystal particles in a vacuum drying oven at 200 degrees Celsius and dry for at least 39 hours; Step 5: Crush the dried quartz single crystal mineral particles into mineral single crystal particles with a particle size of less than 2 mm. Step 6: Grind the mineral single crystal particles into quartz mineral powder with a particle size of 10.68 micrometers to 20.75 micrometers; Step 7: Pack the quartz mineral powder into a paper sealed bag and dry it in a vacuum drying oven at 85 degrees Celsius for 9 days to obtain quartz sample powder.

3. The method for preparing high-density and bulk polycrystalline quartz polymers under hot isostatic pressing according to claim 1, characterized in that: The method for preparing the steel cladding includes: selecting a continuously cast slab of No. 20 low-carbon steel with a wall thickness of 3 mm as the initial raw material for the steel cladding sleeve, heating it to 200 °C, and then using a roughing mill and a finishing mill to cool it to a set temperature through laminar flow, and then coiling it into a steel strip coil by a coiler. This coil undergoes three rolling processes and multiple hot rolling processes including edge trimming to obtain a steel cladding sleeve with dimensions of 55.94 mm (outer diameter) × 88.77 mm (height) × 3 mm (wall thickness); selecting a continuously cast slab of No. 20 low-carbon steel with a wall thickness of 3 mm as the initial raw material for the steel cladding cap, and using the same multiple hot rolling process to prepare the upper and lower sealing caps of the steel cladding, and then welding the sleeve, upper sealing cap, and lower sealing cap together by high-temperature vacuum welding to prepare a complete steel cladding.

4. The method for preparing high-density and bulk polycrystalline quartz polymers under hot isostatic pressing according to claim 1, characterized in that: The quartz sample powder was compacted and sealed to a vacuum degree of 10. –3 The method for a steel cladding with dimensions of 55.94 mm (outer diameter) × 88.77 mm (height) × 3 mm (wall thickness) includes: Step 9: First, vacuum weld the sleeve and lower sealing cap of the steel cladding. Then, place the quartz sample powder inside the steel cladding. After compaction, vacuuming, high-temperature degassing, and high-temperature vacuum welding, the quartz sample powder is compacted and sealed in a vacuum of 10... –3 The steel cladding of Pa was used for vacuuming for at least 75 hours, followed by high-temperature degassing at 400 °C.

5. The method for preparing high-density and bulk polycrystalline quartz polymers under hot isostatic pressing according to claim 1, characterized in that: The purity of the pressure-transmitting medium, argon, is 99.999%; the formula for calculating the amount of argon gas consumed is: ； ； In the formula: parameter P target The target pressure for preparing polycrystalline quartz polymer samples under hot isostatic pressing is based on the target temperature (T) of the hot isostatic pressing experiment. target ) Perform the calculation; parameter P bottle The pressure inside the cylinder represents the inert gas argon; parameter t represents the number of cylinders with a volume of 40 liters and an argon purity of 99.999% required to complete a single hot isostatic pressing experiment on a polycrystalline quartz polymer sample under high temperature and high pressure conditions.

6. The method for preparing high-density and bulk polycrystalline quartz polymers under hot isostatic pressing according to claim 1, characterized in that: The methods for purging argon gas, the pressure-transmitting medium, include: Step 13, Vacuuming, Argon Filling and Furnace Cleaning: (1) Vacuuming: Turn on the gas vacuum pump control switch to evacuate the air in the high-pressure sample chamber that is directly connected to the gas vacuum pump. When the detection value of the vacuum degree instrument digital display reaches 10 –4 (1) When the pressure reaches 15 MPa, turn off the gas vacuum pump; (2) Fill the cylinder directly connected to the argon gas with argon gas, and stop filling the pressure medium when the pressure in the sample chamber reaches 15 MPa; (3) Clean the furnace: turn on the gas vacuum pump and pump the vacuum in the sample chamber to 10 MPa. –4 MPa, repeat the evacuation and filling process three times; Step 14: Pre-pressurize the sample chamber. Calculate the required amount of argon gas. To achieve the target pressure of 114.1 MPa and the target temperature of 940 °C, at least four argon cylinders with an internal pressure of 15 MPa are required. Evenly fill the 15 MPa argon cylinders into the high-pressure pressurization tank of the hot isostatic pressing equipment. Then, through a high-pressure delivery pipeline, freely fill the cylinder with the argon gas from the high-pressure pressurization tank, thereby balancing the pressure in the high-pressure pressurization tank and the pressure in the cylinder. Turn on the diaphragm compressor to pump all the remaining argon gas from the high-pressure tank into the quartz sample chamber of the cylinder, pre-pressurizing the sample chamber to 58.7 MPa.

7. The method for preparing high-density and bulk polycrystalline quartz polymers under hot isostatic pressing according to claim 1, characterized in that: The method employing a multi-gradient hot isostatic pressing approach—first increasing pressure and then increasing temperature—to raise the temperature inside the sample chamber of the cylinder to 940 °C and the pressure to 114.1 MPa, and then holding this temperature and pressure for 4.5 hours includes: Step 15: Within the temperature range of room temperature to 600 °C, using a heating rate of 18.04 °C / min and a pressurization rate of 1.03 MPa / min, raise the temperature inside the sample chamber of the cylinder to 600 °C and the pressure to 89.6 MPa; within the medium temperature range of 600 °C to 860 °C, using a heating rate of 13 °C / min and a pressurization rate of 0.85 MPa / min, raise the temperature inside the sample chamber of the cylinder to 860 °C and the pressure to 106.5 MPa, and maintain the temperature and pressure for 1.0 hour; within the high temperature range of 860 °C to 940 °C, using a heating rate of 5.33 °C / min and a pressurization rate of 0.51 MPa / min, raise the temperature inside the sample chamber of the cylinder to 940 °C and 114.1 MPa, and maintain the temperature and pressure for 4.5 hours.

8. The method for preparing high-density and bulk polycrystalline quartz polymers under hot isostatic pressing according to claim 1, characterized in that: The method of reducing the temperature inside the cylinder sample chamber to 180 °C using a multi-gradient cylinder cooling and depressurization approach includes: using a cooling rate of 5.33 °C / min and a depressurization rate of 0.32 MPa / min to reduce the temperature inside the cylinder sample chamber to 860 °C and the pressure to 109.3 MPa, and maintaining the temperature and pressure at the same level for 1.0 hour; and using a cooling rate of 14.78 °C / min and a depressurization rate of 0.79 MPa / min to reduce the cylinder temperature inside the sample chamber to 180 °C and the pressure to 72.8 MPa.

9. The method for preparing high-density and bulk polycrystalline quartz polymers under hot isostatic pressing according to claim 1, characterized in that: Finally, the methods for depressurizing and cooling to room temperature to obtain polycrystalline quartz polymers include: Step 17, Depressurization: Allow the argon gas in the cylinder of the hot isostatic pressing equipment to flow freely back to the high-pressure pressurizing tank through the pipeline; when the cylinder pressure and the high-pressure pressurizing tank pressure reach equilibrium, turn on the diaphragm compressor to release the gas in the cylinder and discharge all the residual gas through the pipeline. Step 18, Cooling: After all the argon gas in the pipeline has been completely removed, the cooling system connected to the furnace body of the hot isostatic pressing equipment continues to be turned on, and the natural cooling program is started to reduce the temperature inside the furnace from 180 °C to room temperature. Step 19: Open the furnace chamber and remove the steel ladle-clad workpiece; Step 20: Use a diamond saw blade cutter to peel the polycrystalline quartz polymer sample from the steel sheath.

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