Preparation method of high-density and high-densification polycrystalline trachyandesite under high temperature and high pressure conditions

Abstract

The application discloses a preparation method of high-density high-densification polycrystalline trachyandesite under high-temperature high-pressure conditions. –3 The application discloses a preparation method of high-density high-densification polycrystalline trachyandesite under high-temperature high-pressure conditions, which comprises the following steps: completely sealing trachyandesite sample powder in a ladle cover with a vacuum degree of 10 –3 Pa; placing the ladle cover in a graphite furnace cylinder body of a high-pressure container of a hot isostatic pressing device, covering a graphite sealing cover; taking argon as a pressure transmission medium; adopting a multi-gradient hot isostatic pressing forming process of first increasing pressure and then increasing temperature to increase the temperature in the cylinder body sample bin to 950°C and the pressure to 91.5 MPa, and keeping constant temperature and constant pressure for 6.8 hours; adopting a multi-gradient cylinder body temperature and pressure decreasing mode to decrease the temperature in the cylinder body sample bin to 176°C and the pressure to 58.7 MPa; and finally, decreasing the pressure and temperature to room temperature to obtain a polycrystalline trachyandesite aggregate sample; and the technical blank of preparing a large bulk experimental sample of high-densification polycrystalline trachyandesite aggregate under high-temperature high-pressure conditions is solved.

Description

Technical Field

[0001] This invention belongs to the field of experimental sample synthesis technology for large-volume calc-alkaline series magmatic extrusive rocks aggregates – polycrystalline intermediate syenite-trachyte, and particularly relates to a method for preparing high-density, high-compact polycrystalline trachyandesite under high temperature and high pressure conditions. Background Technology

[0002] Intermediate igneous rocks are an important class of igneous rocks whose silica content ranges from 53% to 65%. In terms of mineral composition, they are dominated by the aluminosilicate mineral feldspar, and the percentage of dark minerals in these rocks falls between that of acidic and basic igneous rocks. The Rittmann index, an important parameter characterizing the acidity and alkalinity of igneous rocks, is used to determine their acidity and alkalinity. Based on the Rittmann index (RI), intermediate igneous rocks are mainly divided into: when the RI is less than 3.3, they are calc-alkaline intermediate igneous rocks, called diorite-andesite; when the RI is between 3.3 and 9.0, they are calc-alkaline to alkaline intermediate igneous rocks, called syenite-trachyte; and when the RI is greater than 9.0, they are transitional intermediate igneous rocks, called nepheline syenite-phonolite. Among these, syenite-trachyte can be further divided into intrusive syenite-trachyte and extrusive syenite-trachyte. Intrusive syenite-trachyte can be further subdivided into six different rock types: calc-alkaline syenite, alkaline syenite, monzonite, quartz monzonite, syenite porphyry, and albite porphyry. Syenite and quartz syenite are the most typical calc-alkaline syenites, while nepheline syenite, alkali-ambiridite, and dacite-alkali syenite are the most typical alkaline syenites. Extrusive syenite-trachyte can be further subdivided into four different rock types: calc-alkaline trachyte, alkaline trachyte, trachyandesite, and keratophyre. Based on the calcium oxide weight percentage in extrusive syenite-trachyte, it is mainly divided into: when the calcium oxide weight percentage is higher than 3.5%, it is called calc-alkaline trachyte; when the calcium oxide weight percentage is lower than 3.5%, it is called alkaline trachyte. Based on the ratio of sodium oxide to potassium oxide by weight in extrusive syenite-trachyte, it is mainly divided into the following categories: when the ratio of sodium oxide to potassium oxide by weight is higher than 1.5%, it is called sodium-rich trachyte; when the ratio of sodium oxide to potassium oxide by weight is lower than 1.5%, it is called potassium-rich trachyte.

[0003] Trachyandesite is a typical extrusive rock of the calc-alkaline syenite-trachyte series within intermediate igneous rocks. Its corresponding intrusive rock is monzoite, which lies between trachyte and andesite, and therefore shares the same mineralogical composition. In nature, naturally occurring trachyandesite exhibits red, gray, white, or light yellow surface colors; typical trachytic, interlocking, porphyritic, and vitreous interlocking textures; and vesicular and massive structures. The main constituent minerals of trachyandesite consist of phenocrysts and matrix. Plagioclase, with andesite and plagioclase as typological minerals, is the primary mineral constituting both the phenocrysts and matrix. The most typical plagioclase phenocrysts in trachyandesite are of the high-temperature type, exhibiting distinct zoning and positive reaction rim structures. In trachyandesite, dark minerals are mainly amphibole and biotite, often appearing as phenocrysts with darkened rims. Accessory minerals in trachyandesite are mainly nepheline, leucite, zoisite, zeolite, zircon, sphene, ilmenite, magnetite, and apatite. Calcium-bearing phosphate minerals—apatite—exposed in trachyandesite often exhibit significant pleochroism. The matrix of trachyandesite often contains vesicles or secondary mineral infilling. Typical secondary minerals and vesicle-filling minerals include opal, epidote, chlorite, calcite, zeolite, and iron oxides. In addition, naturally exposed trachyandesite typically undergoes alteration phenomena such as zeolization and alunitization under low-temperature hydrothermal geological processes; under high-temperature hydrothermal geological processes, it typically undergoes alteration phenomena such as silicification, zoisite alteration, kaolinization, and sericitization. To date, geologists have conducted extensive research on the material source and geological origin of trachyandesite, proposing three important academic viewpoints: (1) Geological origin of basaltic magma differentiation: Recent strontium isotope dating results show that trachyandesite samples collected in the field often have similar isotopic geological ages to basalt. Therefore, trachyandesite and basalt have a symbiotic or associated relationship, suggesting that trachyandesite is a product of basaltic magma differentiation in the deep Earth; (2) Geological origin of basaltic magma assimilation: Experimental rock The results of the geochemical study of the rock show that the chemical composition of the trachyandesite produced in the deep crust of the continent is between that of basalt and andesite. It is proposed that the trachyandesite is the result of the geological process of basaltic magma from the deep continental crust of the earth assimilated into granite; (3) Geological origin of plate tectonic movement: During the geological tectonic movement of subduction and collision between continental plates and oceanic plates, a large amount of andesitic magma is generated. When the magma surges to the mantle wedge region, the high temperature andesitic magma it carries causes partial melting of the volatile-rich mantle peridotite, which then forms trachyandesite.

[0004] To investigate the formation mechanisms and occurrence paths of common geological hazards deep within the Earth, such as volcanoes, earthquakes, and debris flows, geologists typically employ high-pressure equipment with multiple large cavities, 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 trachyandesite aggregates under high temperature and pressure conditions. Obtaining a large-sized experimental sample of polycrystalline trachyandesite aggregate, measuring 46.31 mm (diameter) × 71.57 mm (height), is a crucial step in simulating these physical properties under high temperature and pressure conditions. Geologists typically use naturally occurring trachyandesite found in the field as a substitute for polycrystalline trachyandesite as experimental samples. However, naturally occurring trachyandesite has drawbacks: low sample density, numerous impurity minerals (such as nepheline, leucite, zoisite, zeolite, zircon, sphene, ilmenite, magnetite, apatite, opal, epidote, chlorite, calcite, iron oxides, and various framework silicate minerals, island silicate minerals, sodium aluminum silicate minerals, aluminum silicate minerals, hydrous layered silicate minerals, phosphate minerals, carbonate minerals, and spinel group minerals), and the main constituent minerals plagioclase and amphibole. Biotite suffers from numerous insurmountable drawbacks, such as large and unevenly distributed crystal grains, difficulty in eliminating optimal lattice orientation, and significant anisotropy of crystal axes. Consequently, many different high-temperature and high-pressure mineral and rock property simulation teams around the world use natural trachyandesite as the initial sample and employ various high-pressure equipment with multiple large cavities, such as hydrothermal autoclaves, piston cylinder presses, and rotary shear friction testers. However, the experimental data on the physical properties of natural trachyandesite 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.

[0005] 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 rock 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, 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 large-volume polycrystalline trachyandesite aggregates (e.g., with a diameter greater than 40 mm), the top and bottom of the trachyandesite powder inevitably experience significant asymmetric shrinkage due to unidirectional compression during high temperature, high pressure, and quasi-hydrostatic experiments. This results in numerous macroscopic voids and defects during the preparation of large-volume polycrystalline rock aggregates. These macroscopic voids and defects cause wrinkles or pores in the central part of the cross-section of the large-volume polycrystalline trachyandesite aggregate, ultimately making the sample prone to severe porosity or aggregation along the center of the wrinkles or pores. This is the unavoidable shrinkage and porosity effect during the synthesis of large-volume polycrystalline rock aggregates under high temperature, high pressure, and quasi-hydrostatic conditions. The shrinkage and porosity effects of these polycrystalline trachyandesite aggregate samples lead to severe excessive deformation, resulting in numerous voids, fracture wrinkles, and cavities in the prepared bulk polycrystalline trachyandesite aggregate samples. This significantly affects the preparation results of bulk polycrystalline trachyandesite aggregate samples. Therefore, neither natural trachyandesite nor small-sized (no more than 6 mm) trachyandesite 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 large-volume polycrystalline trachyte andesite 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 solubility, friction coefficient, shear stress, and other mineral and rock properties of large-volume calc-alkaline series magmatic extrusive rock aggregates—polycrystalline intermediate syenite-trachyte minerals and rocks—under high-temperature and high-pressure conditions. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a method for preparing high-density, high-compact polycrystalline trachyandesite under high temperature and high pressure conditions, thereby filling the technical gap in the preparation of large-volume experimental samples of high-compact polycrystalline trachyandesite aggregates under high temperature and high pressure conditions. This method provides important experimental sample support for the experimental simulation study of the solubility, friction coefficient, and shear stress of large-volume calc-alkaline series magmatic extrusive rock aggregates—polycrystalline intermediate syenite-trachyte minerals and rock properties—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 testers.

[0007] The technical solution of this invention is:

[0008] A method for preparing high-density, high-compact polycrystalline trachyandesite under high temperature and high pressure conditions, the method comprising: completely sealing trachyandesite sample powder under a vacuum of 10... –3 The steel cladding was placed in the graphite furnace cylinder of the high-pressure vessel of the hot isostatic pressing equipment; the steel cladding was placed in the graphite furnace cylinder, and the graphite sealing cap was placed on it; argon was used as the pressure transmission medium; a multi-gradient hot isostatic pressing process of first increasing the pressure and then increasing the temperature was used to raise the temperature in the cylinder sample chamber to 950 °C and the pressure to 91.5 MPa, and the temperature and pressure were kept constant for 6.8 hours; a multi-gradient cylinder cooling and depressurization method was used to lower the temperature in the cylinder sample chamber to 176 °C and the pressure to 58.7 MPa; finally, the pressure was released and the temperature was lowered to room temperature to obtain a polycrystalline trachyandesite aggregate sample.

[0009] The method for raising the temperature inside the cylinder sample chamber to 950°C and the pressure to 91.5 MPa using a multi-gradient hot isostatic pressing process with prior pressurization followed by heating includes: raising the temperature inside the cylinder sample chamber to 600°C and the pressure to 72.2 MPa within a temperature range of room temperature–600°C using a heating rate of 18.37°C / min and a pressurization rate of 0.78 MPa / min; and raising the temperature inside the cylinder sample chamber to 950°C and the pressure to 91.5 MPa within a high-temperature range of 600°C–950°C using a heating rate of 11.67°C / min and a pressurization rate of 0.64 MPa / min, and maintaining the temperature and pressure at the same level for 6.8 hours.

[0010] The method of reducing the temperature inside the cylinder sample chamber to 176 °C and the pressure to 58.7 MPa using a multi-gradient cylinder cooling and depressurization approach includes: after maintaining a constant temperature and pressure of 91.5 MPa and 950 °C for 6.8 hours, the temperature inside the cylinder sample chamber is reduced to 850 °C and the pressure to 87.2 MPa using a cooling rate of 5 °C / min and a depressurization rate of 0.22 MPa / min, and then maintained at the same temperature and pressure for 1.0 hour; and the temperature inside the cylinder sample chamber is reduced to 176 °C and the pressure to 58.7 MPa using a cooling rate of 10.21 °C / min and a depressurization rate of 0.43 MPa / min.

[0011] Beneficial effects of this invention:

[0012] 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 advanced geochemistry, ore genesis, rock rheology, geodynamics, hot isostatic pressing materials science, hot isostatic pressing powder metallurgy, seismology, igneous magmatism, high-pressure rheology, mineral physics, deep Earth materials science, high-pressure materials science, materials science, and high-pressure experimental mineralogy, large-volume, highly dense polycrystalline trachyandesite aggregate experimental samples were prepared under high temperature and high pressure conditions using an RD80×100‒2000–200 double 2000 type hot isostatic pressing equipment.

[0013] The initial raw material selected for this invention is trachyandesite collected in the field, without any alteration, with a fresh surface, and free of impurities. This trachyandesite is crushed into uniform polycrystalline rock powder. The powder is then 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 cleaning to ensure the trachyandesite sample powder is in a completely sealed environment protected by argon inert gas. The steel sheath containing the trachyandesite sample powder is placed in the sample chamber of an RD80×100‒2000–200 double 2000 type hot isostatic pressing (HIP) device, where it is sintered under high temperature and pressure to form a large, highly dense polycrystalline trachyandesite aggregate. The prepared polycrystalline trachyandesite aggregate sample can be widely used in diagenetic and mineralization experimental simulation studies of the physicochemical properties of minerals and rocks under high temperature and high pressure conditions.

[0014] The steel cladding dimensions used in the hot isostatic pressing test of this invention are: 57.06 mm (outer diameter) × 84.68 mm (height) × 3 mm. The obtained large-size polycrystalline trachyandesite aggregate samples can reach a diameter of 46.31 mm and a height of 71.57 mm. During the hot isostatic pressing (HIP) experiment of the polycrystalline trachyandesite aggregate 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 trachyandesite sample powder in all directions, effectively avoiding the adverse effects of shrinkage porosity and porosity during the HIP experiment. The inert argon gas ensures complete isolation between the trachyandesite sample powder and air within the sample chamber, effectively preventing redox reactions between the trachyandesite 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 trachyandesite aggregate samples, potentially leading to the introduction of impurity ions.

[0015] This invention employs a multi-gradient hot isostatic pressing (HIP) process, first increasing pressure and then increasing temperature, to prepare polycrystalline trachyandesite aggregate experimental samples with excellent physicochemical properties such as fine crystal size, high density, and high purity. This breakthrough overcomes the technical bottleneck of synthesizing large-volume experimental samples of high-density polycrystalline trachyandesite aggregates. Furthermore, this invention's multi-gradient HIP process is not limited by the shape and size of the sample, allowing for the preparation of complex polycrystalline rock 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's multi-gradient HIP process can obtain polycrystalline trachyandesite aggregate experimental samples with near-theoretical density and extremely high sample strength.

[0016] This invention, based on an RD80×100‒2000–200 double 2000-type hot isostatic pressing (HIP) device, employs a multi-gradient HIP molding process of first increasing pressure and then increasing temperature. For the first time, it obtains experimental samples of large-volume, uniformly distributed, high-density, high-compactness, and high-strength polycrystalline trachyte andesite aggregates under conditions of 91.5 MPa and 950 °C. These samples can be widely applied to experimental simulations of the solubility, friction coefficient, and shear stress properties of large-volume calc-alkaline series magmatic extrusive rock aggregates—polycrystalline intermediate syenite-trachyte minerals—on multi-faceted, large-cavity high-pressure equipment 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 mechanisms of common geological disasters such as deep-earth volcanoes, earthquakes, and debris flows. Attached Figure Description

[0017] 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 changes in the sample chamber over time during the preparation of polycrystalline rough andesite polymer are shown in the figure.

[0018] Figure 2 To obtain fine-grained coarse andesite sample powder by crushing and grinding with the aid of a jaw crusher (model: BB 200) and a high-efficiency Retsch disc vibratory mill (model: RS200), optical microscopic observation results of the coarse andesite sample before the hot isostatic pressing experiment were obtained using a high-magnification, high-precision Olympus SZX16 research-grade stereomicroscopic imaging platform.

[0019] Figure 3 This document presents the optical microscopic observation results of the surface morphology and grain size distribution of a polycrystalline trachyandesite aggregate sample, a product of hot isostatic pressing experiments conducted at 91.5 MPa and 950 °C, using the high-precision Olympus SZX16 research-grade stereomicroscopic imaging platform. Detailed Implementation

[0020] A method for preparing high-density, high-compact polycrystalline trachyandesite under high temperature and high pressure conditions, comprising:

[0021] Step 1: Square, dense, massive trachyandesite was used as the initial sample. A high-precision Olympus SZX16 research-grade stereomicroscopy platform was used to accurately measure the grain size of the initial sample. The smallest sample size of the trachyandesite was 5.4 mm and the largest sample size was 11.2 mm. If the trachyandesite sample size 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 trachyandesite samples free of other associated / symbiotic minerals and impurities. If the trachyandesite sample size is too small, it is difficult to effectively separate trachyandesite from framework silicate minerals, island silicate minerals, sodium aluminum silicate minerals, aluminum silicate minerals, hydrous layered silicate minerals, phosphate minerals, carbonate minerals, and spinel group minerals of different compositions, such as nepheline, leucite, zoisite, zeolite, zircon, sphene, ilmenite, magnetite, apatite, opal, epidote, chlorite, calcite, and iron oxides. Furthermore, this invention requires the selection of trachyandesite samples with a relatively large weight, which will consume a significant amount of time and manpower.

[0022] Step 2: Place the selected rough andesite block sample on an ultrasonic cleaner and use acetone, alcohol and deionized water as cleaning solutions in sequence for ultrasonic cleaning for 15 minutes to remove impurities from the sample surface.

[0023] Step 3: Using a high-magnification, high-precision Olympus SZX16 research-grade stereomicroscopic imaging platform, carefully select 300 grams of trachyandesite blocky samples with uniform gray-green color, fresh surface, and no other impurity minerals to ensure that the initial trachyandesite sample has high purity before the hot isostatic pressing experiment under high temperature and high pressure conditions.

[0024] Step 4: Place the carefully selected trachyandesite block samples in a vacuum drying oven at 200 degrees Celsius for at least 18 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 trachyandesite sample, making it difficult to accurately weigh the initial trachyandesite sample during further grinding. If the temperature is too high, it may cause a decomposition reaction in the trachyandesite, ultimately severely affecting the preparation effect of the hot isostatic pressing (HIP) experiment sample under high temperature and high pressure conditions.

[0025] Step 5: Place the initial trachyandesite sample on a jaw crusher (model: BB 200), set the instrument's drive power to 1.5 kW, and use a crushing time of 10 minutes to crush the trachyandesite into rock particles with a diameter of less than 2 mm. The purpose is to fully crush the sample to obtain trachyandesite samples with a medium particle size (less than 2 mm).

[0026] Step 6: Place the sample on a high-efficiency Retsch disc vibratory grinder (model: RS200), using a high-speed mode of 1270 rpm and setting the instrument's drive power to 1.5 kW. Grind the rock particles into fine-grained coarse andesite sample powder with a particle size of 13.75 μm to 23.46 μm (see...). Figure 2 The amount of trachyandesite sample ground in a single cycle is 100 grams, and the grinding time is 5 minutes. Trachyandesite powder within this particle size range has a large specific surface area (surface area per unit weight of rock powder), which significantly increases the contact area between particles due to pressure and temperature effects. This is more conducive to forming strong bonding forces between the particles of the trachyandesite powder during the hot isostatic pressing experiment of this invention, thereby greatly improving the compactness and density of the prepared fine-grained polycrystalline trachyandesite aggregate sample.

[0027] Step 7: Considering that the fine-grained coarse andesite sample powder is very easy to absorb water in the air, it is placed in a paper sealed bag and dried in a vacuum drying oven at 85 degrees Celsius for 10 days to completely remove the adsorbed water on the surface of the sample powder.

[0028] Step 8: In the process of preparing polycrystalline rough andesite 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 rough andesite 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 950 °C and the pressure of 91.5 °C required for the preparation of polycrystalline rough andesite polymer samples under the HIP conditions of this invention. MPa; (3) The steel sheath material of low carbon steel (No. 20 steel) has good air tightness, which ensures that the powder of rough andesite sample 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 (No. 20 steel) also has excellent properties such as relatively easy edge rolling, cutting, processing, deformation and good welding performance.

[0029] 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. 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 the cladding for the hot isostatic pressing test of rough andesite sample powder with dimensions of 57.06 mm (outer diameter) × 84.68 mm (height) × 3 mm (wall thickness).

[0030] 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 the hot isostatic pressing test of rough andesite sample powder.

[0031] Step 9: First, vacuum weld the sleeve and lower sealing cap of the steel cladding. Then, place the dried rough andesite sample powder inside the steel cladding. After a series of processes including compaction, vacuuming, high-temperature degassing, and high-temperature vacuum welding, the rough andesite sample powder is completely sealed in a vacuum of 10... –3Pa is in the steel ladle sleeve.

[0032] Achieving such a low vacuum level within the steel-clad cavity requires at least 68 hours of evacuation, while simultaneously subjecting the sample to high-temperature degassing at 400 °C to ensure the trachyandesite powder is completely in a sealed vacuum environment and that all moisture in the sample is removed. The trachyandesite 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 rough andesite sample powder is fully compacted, which can ensure that a sufficient amount of rough andesite sample powder is sealed in the steel sleeve, which will help increase the density of the polycrystalline rough andesite aggregate of the hot isostatic pressing test product, thereby greatly improving the preparation effect of the final product bulk polycrystalline rough andesite aggregate sample; (2) ensuring that the rough andesite sample powder is fully compacted, which can ensure the filling amount of rough andesite sample powder sealed in the steel sleeve, which will help enhance the compactness between the rough andesite sample powder particles, effectively avoiding excessive deformation of the sample during the hot isostatic pressing test, thereby greatly improving the compactness of the final product bulk polycrystalline rough andesite aggregate sample; (3) maintaining 10 –3 The 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 rough andesite sample powder sealed inside; (4) Under the condition of 400 °C, the rough andesite sample powder is degassed at high temperature, completely removing any water vapor that may be present in the sample powder; (5) The steel sheath is welded by high temperature vacuum, which effectively isolates the weld head from direct contact with air, and the high temperature oxidation of the metal weld point can be completely avoided, which will greatly enhance the sealing performance of the steel sheath.

[0033] Step 10: Carefully place the steel sleeve containing the rough andesite 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 rough andesite 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.

[0034] 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 trachyandesite 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 pipelines and circuits of the high-pressure device, ensuring the absolute safety of the operators during HIP experiments.

[0035] 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.

[0036] 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 and 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 rough andesite sample powder compaction to complete the hot isostatic pressing 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.

[0037] Step 12: In this invention, argon gas is used as the pressure transmission medium. During the preparation of polycrystalline trachyandesite polymers on an RD80×100‒2000–200 double 2000-type hot isostatic pressing (HIP) equipment, 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 rock powder, which is difficult to mold, the use of argon gas as the 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 large-volume polycrystalline trachyandesite polymer products.

[0038] This invention employs a multi-gradient hot isostatic pressing (HIP) process, involving prior pressurization followed by heating, to synthesize large-volume experimental samples of high-density, high-compactness, and high-purity polycrystalline trachyandesite aggregates. The target pressure and temperature for the HIP experiment are 91.5 MPa and 950 °C, respectively. If the selected target pressure and temperature are too low, the steel cladding used to seal the trachyandesite 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—large-volume, high-density, and high-compact polycrystalline trachyandesite aggregate samples. Conversely, if the selected target pressure and temperature are too high, the polycrystalline calc-alkaline series of neutral syenite-trachyte extrusive rocks—trachyandesite samples will undergo decomposition reactions during the HIP experiment, thus having an extremely adverse effect on the prepared polycrystalline trachyandesite aggregate product.

[0039] 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 the rough andesite 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 forming experiments, high-temperature low-pressure empty furnace HIP forming experiments, and high-temperature high-pressure empty furnace HIP forming experiments of the rough andesite sample powder, the precise temperature and pressure calibration of the rough andesite sample cavity is performed. Finally, based on the RD80×100‒2000–200 double 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 rough andesite aggregate HIP experiment. The formula for calculating the amount of argon gas consumed is as follows:

[0040] (1);

[0041] (2);

[0042] In the formula: parameter P target The target pressure for preparing polycrystalline trachyandesite aggregate samples under hot isostatic pressing (T) is based on the target temperature of the hot isostatic pressing experiment (T).target ) Perform the calculation; parameter P bottle The pressure inside the cylinder represents the inert gas argon; 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 trachyandesite aggregate sample under high temperature and high pressure conditions.

[0043] 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.

[0044] Step 14: Pre-filling and pressurizing 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 91.5 MPa and the target temperature of 950 °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 rough andesite sample chamber of the cylinder, so that the sample chamber in the cylinder is pre-filled and pressurized to 48.9 MPa.

[0045] Step 15: Multi-gradient cylinder block heating and pressurization (see...) Figure 1). Taking into account the target pressure and temperature for preparing polycrystalline trachyandesite aggregate samples in hot isostatic pressing (HIP), as well as the safety, reliability, and durability of the graphite heating element itself, a multi-gradient cylinder heating and pressurization HIP procedure was precisely controlled and automatically adjusted. The specific steps are as follows: Within the temperature range of room temperature to 600 °C, a heating rate of 18.37 °C / min and a pressurization rate of 0.78 MPa / min were used to raise the temperature in the cylinder sample chamber to 600 °C and the pressure to 72.2 MPa; In the high-temperature zone of 600 °C to 950 °C, a heating rate of 11.67 °C / min and a pressurization rate of 0.64 MPa / min were used to raise the temperature in the cylinder sample chamber to 950 °C and the pressure to 91.5 MPa, and the temperature and pressure were maintained at constant for 6.8 hours to ensure that the polycrystalline calc-alkaline series of neutral syenite-trachyte extrusive rock-trachyandesite samples were fully compacted and cemented. As the temperature rises, the argon gas inside the sealed cylinder expands dramatically. Since the cylinder volume remains constant, the argon gas volume is uniformly compressed, generating uniform high pressure. Ultimately, the pressure inside the sample chamber is maintained at 91.5 MPa. Trachyandesite is formed gradually through magma eruptions during global plate tectonics, from relatively active to relatively stable geological periods. It is often exposed in the late stages of orogeny or in areas of relatively stable tectonic activity. Its main constituent minerals (plagioclase, amphibole, and biotite) exhibit complex crystal morphology, distinct preferred lattice orientations, and anisotropic physicochemical properties.

[0046] This invention employs a multi-gradient hot isostatic pressing (HIP) process, first increasing pressure and then increasing temperature, to prepare polycrystalline trachyandesite aggregates. The trachyandesite sample powder is held under pressure and temperature of 91.5 MPa and 950 °C for 6.8 hours to ensure a sufficiently long stepped holding time. If the holding time is too short, it is difficult to form strong bonding forces between the particles of the trachyandesite sample powder with its diverse crystal morphologies, and it is also difficult to overcome the influence of many unfavorable factors such as the preferred orientation and anisotropy of the trachyandesite crystal lattice, thus affecting the density and strength of the final bulk polycrystalline trachyandesite aggregate sample. If the holding time is too long, although a highly dense and strong polycrystalline trachyandesite aggregate can be obtained, the final bulk polycrystalline trachyandesite aggregate 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.

[0047] Step 16: Multi-gradient cylinder cooling and depressurization. After the rough andesite sample powder was kept at a constant temperature and pressure of 91.5 MPa and 950 °C for 6.8 hours, the temperature inside the cylinder sample chamber was reduced to 850 °C and the pressure to 87.2 MPa at a cooling rate of 5 °C / min and a depressurization rate of 0.22 MPa / min, and kept at the same temperature and pressure for 1.0 hour. After being kept at the same temperature and pressure for 1.0 hour, the temperature inside the cylinder sample chamber was reduced to 176 °C and the pressure was reduced to 58.7 MPa at a relatively slow cooling rate of 10.21 °C / min and a relatively slow depressurization rate of 0.43 MPa / min. Compared to the pressurization process, a slower cooling and depressurization rate is adopted. This is mainly because if the cooling and depressurization rates are too fast, the internal stress of the steel cladding will not be fully released, which will lead to the fragmentation and damage of the bulk polycrystalline trachyandesite aggregate product, thus seriously affecting the preparation effect.

[0048] This invention selects a sample chamber temperature of 176 °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 temperature exceeds 180 °C, the resulting internal pressure is too high, which could easily damage the graphite heating furnace and potentially cause a safety accident with the HIP equipment. Conversely, if the sample chamber temperature is below 160 °C, the resulting internal pressure is too low, making 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.

[0049] 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.

[0050] Step 18, Cooling. After all the inert argon gas in the pipeline has been completely removed, the cooling system connected to the hot isostatic pressing furnace body continues to be turned on, and the natural cooling program is started to reduce the temperature inside the furnace from 176 °C to room temperature (~25 °C).

[0051] Step 19: Set the control program for the hot isostatic pressing (HIP) equipment, open the furnace chamber, carefully remove the polycrystalline rough andesite polymer steel-clad workpiece sealed after the HIP experiment, and accurately measure the dimensions of the steel cladding after the HIP forming experiment: 52.31 mm (outer diameter) × 81.57 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 19.04%. This invention exhibits such a large volumetric shrinkage rate (η) of the steel sheath. 钢包套 =19.04%), confirming that the steel cladding used to seal and encapsulate the rough andesite sample powder underwent sufficient compression and effective deformation during the hot isostatic pressing experiment.

[0052] Step 20: Using a high-speed diamond saw blade cutter with a 1.0 mm thick diamond saw blade, the polycrystalline trachyandesite aggregate sample was carefully peeled from the steel ladle. The weight of the sample after the experiment was accurately measured to be 299 grams, and the weight of the steel ladle was 500 grams. This indicates that the weight of the trachyandesite 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 trachyandesite aggregate sample obtained after the HIP experiment: 46.31 mm (diameter) × 71.57 mm (height). Comparing the initial volume of the trachyandesite 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. 粗面安山岩 Its calculation formula can be expressed as: η 粗面安山岩 =(V 实验前粗面安山岩 –V 实验后粗面安山岩 ) / V 实验前粗面安山岩 The volume shrinkage rate (η × 100%) is 21.17%. This invention exhibits such a large volume shrinkage rate (η) in the trachyandesite sample powder. 粗面安山岩 =21.17%), confirming that during the hot isostatic pressing experiment, the rough andesite sample powder placed in the steel cladding was fully compacted and sintered under high temperature and high pressure conditions.

[0053] This invention utilizes an RD80×100‒2000–200 dual 2000-type hot isostatic pressing (HIP) apparatus to synthesize a polycrystalline trachyandesite polymer from the initial material—a single-phase trachyandesite—which is then crushed into medium-sized trachyandesite particles, ground into fine-grained trachyandesite powder, and finally synthesized into a polycrystalline trachyandesite polymer. A multi-gradient HIP process, involving prior pressurization followed by heating, is employed to prepare high-density, highly compact, high-purity, and large-volume polycrystalline trachyandesite polymers. No other impurity phases are introduced during the entire preparation process, resulting in polycrystalline trachyandesite polymer samples with 100% purity.

[0054] Under epoxy resin inlay protection, a representative sample (17 mm × 17 mm cross-section) was cut from the polycrystalline trachyandesite polymer workpiece, a product of hot isostatic pressing experiments. The sample underwent epoxy resin inlay protection, cutting, grinding, and surface polishing. Using a high-precision Olympus SZX16 research-grade stereomicroscopic imaging platform, the surface morphology and grain size distribution characteristics of the experimental product—the polycrystalline trachyandesite polymer—were tested. The test results (see...) Figure 3 The polycrystalline trachyandesite aggregate 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 cladding and inert argon gas pressure transmission medium throughout the hot isostatic pressing (HIP) experiment, ensuring the sample powder remains in a closed vacuum environment. This effectively isolates the aggregate from gases such as nitrogen, oxygen, and water vapor, thus achieving uniform particle distribution, no particle growth, and no recrystallization in the polycrystalline trachyandesite aggregate. 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 trachyandesite aggregate products, such as particle growth, uneven particle distribution, and recrystallization.

[0055] High-resolution scanning electron microscopy was used to observe the microstructure of polycrystalline trachyandesite aggregates obtained from hot isostatic pressing experiments, and precise density tests were performed. The obtained polycrystalline trachyandesite aggregates 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 trachyandesite aggregate samples: (1) a higher pre-pressurization pressure (48.9 MPa); (2) a multi-gradient gradually decreasing cylinder heating mode, i.e., a heating rate of 18.37 °C / min in the low-temperature zone (room temperature–600 °C) and a heating rate of 11.67 °C / min in the medium-high temperature zone (600 °C–950 °C); (3) a multi-gradient gradually decreasing cylinder pressurization mode, i.e., a pressurization rate of 0.78 MPa / min in the low-pressure zone (48.9 MPa–72.2 MPa) and a pressurization rate of 0.64 MPa / min in the medium-high pressure zone (72.2 MPa–91.5 MPa); (4) a multi-gradient gradually steepening cylinder cooling mode, i.e., a cooling rate of 0.64 MPa / min in the high-temperature zone (950 °C–92.2 MPa). (5) A multi-gradient cylinder depressurization mode with gradually steepening pressure, i.e., a depressurization rate of 0.22 MPa / min under the high pressure zone of 91.5 MPa–87.2 MPa and a depressurization rate of 0.43 MPa / min under the medium and low pressure zone of 87.2 MPa–58.7 MPa; (6) A multi-gradient cylinder constant temperature and constant pressure mode, i.e., a sufficiently long constant temperature and constant pressure of 6.8 hours at the highest temperature (950 °C) and highest pressure (91.5 MPa) during the hot isostatic pressing experiment; and a constant temperature and constant pressure of 1.0 hours at the temperature of 850 °C and the pressure of 87.2 MPa during the cooling and depressurization process in the hot isostatic pressing experiment. All these optimized and improved hot isostatic pressing (HIP) experimental schemes can promote sufficient diffusion and particle aggregation between trachyandesite 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 trachyandesite aggregate sample produced by HIP.In addition, this invention applies a higher temperature (950 °C), a higher pressure (91.5 MPa), and a sufficiently long heat and pressure holding time (6.8 hours) to promote the formation of good cementation between the particles of the trachyandesite sample powder, thereby greatly improving the density and strength of the polycrystalline trachyandesite aggregate 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 prepared product that exist in the existing technology for synthesizing island silicate mineral single crystals using quasi-hydrostatic presses such as YJ-3000t and Kawai-1000t.

[0056] The Archimedes method using organically combined secondary deionized water and the water intrusion method for porous and complex structures were employed to accurately measure the density of polycrystalline trachyandesite aggregate samples obtained from hot isostatic pressing experiments. The measured density of the polycrystalline trachyandesite aggregate was 2.87 g / cm³. 3 This density value falls exactly within the theoretical density of 2.55 g / cm³ for naturally collected trachyandesite, as measured by geologists. 3 –2.90 g / cm 3Within the specified range, the obtained bulk polycrystalline trachyandesite aggregate samples exhibited extremely high density. The achievement of such high-density polycrystalline trachyandesite aggregate products is highly related to the optimized molding process employed during this hot isostatic pressing experiment, including pretreatment of the trachyandesite sample powder raw material, selection of No. 20 steel sample cladding, a reasonable cooling and depressurization hot isostatic pressing molding process, and high-temperature degassing at 400 °C. Pretreatment of rough andesite sample powder raw materials, specifically fine-grained rough andesite sample powder with a particle size of 13.75 μm to 23.46 μm, is performed. This particle size range of rough andesite has a large specific surface area of ​​rock powder, significantly increasing the contact area between sample particles. This is more conducive to the formation of strong and good cementation, thereby greatly increasing the density of the prepared polycrystalline rough andesite aggregate sample. A 3 mm thick 20# low-carbon steel continuous casting slab is used as the steel cladding. This cladding possesses excellent physical properties such as low strength, low hardness, high plasticity, and good toughness, thus uniformly transferring the high pressure borne by the cladding to the rough andesite sample powder enclosed within it, further increasing the density of the prepared polycrystalline rough andesite aggregate sample. An optimized and improved cooling and depressurization hot isostatic pressing process is employed, particularly using a relatively slow multi-gradient cylinder depressurization mode (pressurization rate: 0.64 MPa / min – 0.78 MPa / min; depressurization rate: 0.22). (MPa / min – 0.43 MPa / min) ensures that the internal stress of large-volume polycrystalline trachyandesite 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 trachyandesite polymer sample. A high-temperature degassing optimization molding process at 400 °C is used. The trachyandesite sample powder is sealed in a steel sleeve and subjected to high-temperature vacuum degassing at 400 °C to minimize gas residue, thereby obtaining polycrystalline trachyandesite 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, high-compact polycrystalline trachyandesite under high temperature and high pressure conditions, characterized in that: The method includes: completely sealing the trachyandesite sample powder under a vacuum of 10... –3 The steel cladding was placed in the graphite furnace cylinder of the high-pressure vessel of the hot isostatic pressing equipment; the steel cladding was placed in the graphite furnace cylinder, and the graphite sealing cap was placed on it; argon was used as the pressure transmission medium; a multi-gradient hot isostatic pressing process of first increasing the pressure and then increasing the temperature was used to raise the temperature in the cylinder sample chamber to 950 °C and the pressure to 91.5 MPa, and the temperature and pressure were kept constant for 6.8 hours; a multi-gradient cylinder cooling and depressurization method was used to lower the temperature in the cylinder sample chamber to 176 °C and the pressure to 58.7 MPa; finally, the pressure was released and the temperature was lowered to room temperature to obtain a polycrystalline trachyandesite aggregate sample.

2. The method for preparing high-density, high-compact polycrystalline trachyandesite under high temperature and high pressure conditions according to claim 1, characterized in that: The method for preparing the rough andesite sample powder includes: Step 1: Select square, dense, massive trachyandesite samples with a minimum sample size of 5.4 mm and a maximum sample size of 11.2 mm as initial samples; Step 2: Place the selected rough andesite block sample on an ultrasonic cleaner and use acetone, alcohol and deionized water as cleaning solutions in sequence for ultrasonic cleaning for 15 minutes. Step 3: Select 300 grams of rough andesite block samples that are uniformly grayish-green in color, have a fresh surface, and are free of impurities. Step 4: Place the trachyandesite block sample in a vacuum drying oven at 200 degrees Celsius and dry for at least 18 hours; Step 5: Crush the trachyandesite into rock particles with a diameter of less than 2 mm; Step 6: Grind the rock particles into trachyandesite sample powder with a particle size of 13.75 micrometers to 23.46 micrometers; Step 7: Pack the rough andesite sample powder into a paper sealed bag and dry it in a vacuum drying oven at 85 degrees Celsius for 10 days.

3. The method for preparing high-density, high-compact polycrystalline trachyandesite under high temperature and high pressure conditions according to claim 1, characterized in that: The methods for preparing steel sheaths include: Step 8: Select a continuous casting slab of No. 20 low carbon steel with a wall thickness of 3 mm, heat it to 200 °C, and then use the roughing mill and finishing mill to cool it to the set temperature through laminar flow. The slab 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 steel cladding sleeve with dimensions of 57.06 mm (outer diameter) × 84.68 mm (height) × 3 mm (wall thickness). A continuous casting slab of No. 20 low-carbon steel with a wall thickness of 3 mm was selected. The same hot rolling process was used to prepare the upper and lower sealing caps of the steel cladding. The cladding, upper and lower sealing caps were welded together by high-temperature vacuum welding to prepare a complete steel cladding.

4. The method for preparing high-density, high-compact polycrystalline trachyandesite under high temperature and high pressure conditions according to claim 1, characterized in that: The rough andesite sample powder was completely sealed in a vacuum of 10. –3 The methods in the steel ladle sleeve of Pa include: Step 9: Vacuum weld the sleeve and lower sealing cap of the steel cladding. Then, place the dried rough andesite sample powder inside the steel cladding. After compaction, vacuuming, high-temperature degassing, and high-temperature vacuum welding, the rough andesite sample powder is completely sealed in a vacuum of 10... –3 The sample was placed in a steel bladder containing Pa; vacuum was applied for at least 68 hours, and the sample was degassed at 400 °C.

5. The method for preparing high-density, high-compact polycrystalline trachyandesite under high temperature and high pressure conditions according to claim 1, characterized in that: The argon gas purity is 99.999%; the formula for calculating the amount of argon gas consumed is: (1)； (2)； In the formula: parameter P target The target pressure for preparing polycrystalline trachyandesite aggregate samples under hot isostatic pressing (T) is based on the target temperature of the hot isostatic pressing experiment (T). 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 rough andesite polymer sample under high temperature and high pressure conditions.

6. The method for preparing high-density, high-compact polycrystalline trachyandesite under high temperature and high pressure conditions according to claim 1, characterized in that: The methods for purging argon gas, the pressure-transmitting medium, include: Step 13, Vacuuming: Turn on the gas vacuum pump control switch to evacuate the air sealed in the high-pressure sample chamber, which is directly connected to the gas vacuum pump. Wait until the reading on the vacuum gauge reaches 10. –4 At MPa, turn off the gas vacuum pump; Fill the cylinder directly connected to argon gas with argon gas, and stop filling when the pressure in the sample chamber reaches 15 MPa; Clean the furnace: Turn on the gas vacuum pump and evacuate the vacuum in the sample chamber to 10 MPa. –4 MPa, repeat the evacuation and filling process three times; Step 14, Pre-pressurization of the sample chamber: Calculate the amount of argon gas required, at least 4 argon cylinders with an internal pressure of 15 MPa are needed; uniformly fill the 15 MPa argon cylinders into the high-pressure pressurization tank of the hot isostatic pressing equipment, and then freely fill the cylinder with the argon gas from the high-pressure pressurization tank through the high-pressure delivery pipeline, so that the pressure in the high-pressure pressurization tank and the pressure in the cylinder reach equilibrium; turn on the diaphragm compressor to pump all the remaining argon gas in the high-pressure tank into the rough andesite sample chamber of the cylinder, so that the sample chamber in the cylinder is pre-pressurized to 48.9 MPa.

7. The method for preparing high-density, high-compact polycrystalline trachyandesite under high temperature and high pressure conditions according to claim 1, characterized in that: The method for raising the temperature inside the cylinder sample chamber to 950 °C and the pressure to 91.5 MPa using a multi-gradient hot isostatic pressing process with prior pressurization followed by heating includes: raising the temperature inside the cylinder sample chamber to 600 °C and the pressure to 72.2 MPa within a temperature range of room temperature–600 °C using a heating rate of 18.37 °C / min and a pressurization rate of 0.78 MPa / min; and raising the temperature inside the cylinder sample chamber to 950 °C and the pressure to 91.5 MPa within a high-temperature range of 600 °C–950 °C using a heating rate of 11.67 °C / min and a pressurization rate of 0.64 MPa / min, and maintaining the temperature and pressure at the same level for 6.8 hours.

8. The method for preparing high-density, high-compact polycrystalline trachyandesite under high temperature and high pressure conditions according to claim 1, characterized in that: The method of reducing the temperature inside the cylinder sample chamber to 176 °C and the pressure to 58.7 MPa using a multi-gradient cylinder cooling and depressurization approach includes: after maintaining a constant temperature and pressure of 91.5 MPa and 950 °C for 6.8 hours, the temperature inside the cylinder sample chamber is reduced to 850 °C and the pressure to 87.2 MPa using a cooling rate of 5 °C / min and a depressurization rate of 0.22 MPa / min, and then maintained at the same temperature and pressure for 1.0 hour; and the temperature inside the cylinder sample chamber is reduced to 176 °C and the pressure to 58.7 MPa using a cooling rate of 10.21 °C / min and a depressurization rate of 0.43 MPa / min.

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