Preparation method of high-density bulk polycrystalline potassium feldspar aggregate under high temperature and high pressure conditions

Abstract

This invention discloses a method for preparing high-density bulk polycrystalline potassium feldspar polymers under high temperature and high pressure conditions, wherein potassium feldspar sample powder is sealed in 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 (HIP) equipment, and a graphite sealing cap was placed on top. Argon gas was used as the pressure transmission medium. A multi-gradient HIP process was adopted to raise the temperature in the sample chamber of the cylinder to 1080 °C and the pressure to 85.9 MPa. After holding the temperature and pressure for 8.1 hours, the temperature in the sample chamber of the cylinder was lowered to 171 °C and the pressure to 51.9 MPa at a cooling rate of 15.15 °C / min and a depressurization rate of 0.57 MPa / min. Finally, the pressure was released and the sample was cooled to room temperature to obtain polycrystalline potassium feldspar polymer. This process fills the technical gap in the preparation of large-volume experimental samples of high-density polycrystalline potassium feldspar polymers under high temperature and high pressure conditions.

Description

Technical Field

[0001] This invention belongs to the field of experimental sample synthesis technology of bulk framework-structured alkaline feldspar series oxygen-containing salt mineral polymers - polycrystalline alkali metal or alkaline earth metal aluminosilicate minerals, and particularly relates to a method for preparing high-density bulk polycrystalline potassium feldspar polymers under high temperature and high pressure conditions. Background Technology

[0002] Acidic igneous rocks, also known as granite-rhyolite rocks, are rocks with a silica content greater than 66% in their chemical composition. They are typical supersaturated silicate rocks, with high potassium oxide and sodium oxide content, averaging 6% to 8%, while calcium oxide, ferric oxide, and ferrous oxide content are relatively low. They can be classified as intrusive or extrusive. When the Rittmann index in acidic igneous rocks is less than 3.3, they are called calc-alkaline acidic igneous rocks; when the Rittmann index is between 3.3 and 9.0, they are called alkaline acidic igneous rocks, with calc-alkaline acidic igneous rocks being the most common. Intrusive acidic igneous rocks mainly include: plutonic acidic igneous rocks, intermediate-plutonic acidic granites, and epi-acidic granites, with granite, granodiorite, and granite porphyry being the main representative rocks. In a narrow sense, granite refers to a large class of intrusive rocks composed of three main rock-forming minerals: quartz, potassium feldspar, and plagioclase, with quartz content exceeding 20% ​​and the combined content of quartz, potassium feldspar, and plagioclase exceeding 85%. In reality, within granites, as quartz content decreases while potassium feldspar content increases, a transition to syenite is observed; conversely, as quartz content decreases while plagioclase content increases, a transition to diorite is observed. Rocks with quartz content between 5% and 20% and exhibiting distinctly similar morphological characteristics are collectively called transitional rocks, such as quartz diorite, quartz monzonite, and quartz syenite. In a broader sense, granite includes transitional rocks and granite in the narrow sense. Geological field observations indicate that these transitional rocks and granite in the narrow sense often develop within the same intrusive body, exhibiting a gradual transition through rock association or symbiosis, and are closely related in terms of geological genesis and spatiotemporal distribution. In addition to these minerals, minor minerals, accessory minerals, and impurities in granite mainly consist of biotite, amphibole, pyroxene, pebbles, diopside, aegirine, nephrite, apatite, zircon, epidote, rutile, and magnetite. The alteration of biotite into chlorite is also quite common. Although the content of these minor minerals, accessory minerals, and impurities in granite is not high, their variety is significant for exploring the geological genesis, stratigraphic age, magmatic evolution history, and diagenetic and mineralization specificity of granite.

[0003] As the most typical oxygen-containing salt mineral of the alkaline feldspar series, potassium feldspar is mainly distributed in calc-alkaline granites. It is an important rock-forming mineral widely present in the middle and upper crust, with its potassium oxide content reaching as high as 7%. Granites with such high potassium feldspar content and composed of potassium feldspar, quartz, and plagioclase as the three main rock-forming minerals are usually called potassium feldspar granites. Potassium feldspar exposed in calc-alkaline granites mainly includes microcline, orthoclase, striated feldspar, and sanidine, often containing small amounts of associated / symbiotic impurities such as muscovite, biotite, kaolinite, montmorillonite, amphibole, garnet, hematite, magnetite, rutile, nepheline, and tourmaline. Sanidine, as a major high-temperature variant, is exposed in shallow intrusive acidic igneous rocks and can also appear in extrusive acidic igneous rocks. Potassium feldspar, typically found in granites, exists in two polymorphs: monoclinic and triclinic. These polymorphs can be clearly identified through X-ray diffraction and vacuum Fourier transform infrared spectroscopy. Generally, the presence of these two completely different crystal forms (monclinic and orthorhombic) in potassium feldspar exhibits a significant positive correlation with crystal order, which is of paramount scientific importance for systematically revealing the origin and geological genesis of magmatic materials in granite source regions.

[0004] 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 potassium feldspar aggregates under high temperature and pressure conditions. Obtaining a large-sized polycrystalline potassium feldspar aggregate experimental sample (46.93 mm (diameter) × 69.45 mm (height)) is a crucial step in simulating these physical properties under high temperature and pressure conditions. Geologists typically use naturally occurring potassium feldspar found in the field as a substitute for polycrystalline potassium feldspar aggregates in their experimental samples. However, natural potassium feldspar samples often suffer from low density, contain numerous impurities (such as muscovite, biotite, kaolinite, montmorillonite, amphibole, garnet, hematite, magnetite, rutile, nepheline, tourmaline, and other hydrous layered aluminosilicate minerals, hydrous chain silicate minerals, island silicate minerals, spinel group minerals, dioxide minerals, framework silicate minerals, and hydrous cyclic borosilicate minerals), and have varying potassium feldspar single-crystal grain sizes among the main constituent minerals. Due to its large size and uneven distribution, difficulty in eliminating the preferred orientation of the crystal lattice, and significant anisotropy of the crystal axis, the natural potassium feldspar has many insurmountable drawbacks. As a result, many different high-temperature and high-pressure mineral and rock property simulation teams around the world use natural potassium feldspar 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. However, the experimental data on the physical properties of natural potassium feldspar 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 mechanism and occurrence mechanism 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 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 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 bulk polycrystalline potassium feldspar aggregates (e.g., with a diameter greater than 40 mm), the top and bottom of the potassium feldspar powder inevitably experience significant asymmetric shrinkage 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 aggregates. These macroscopic voids and defects cause wrinkles or pores in the central part of the cross-section of the bulk polycrystalline potassium feldspar 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 aggregates under high temperature, high pressure, and quasi-hydrostatic conditions. The shrinkage and porosity effects of these polycrystalline potassium feldspar polymer samples lead to severe excessive deformation, resulting in numerous voids, fracture wrinkles, and cavities in the prepared bulk polycrystalline potassium feldspar polymer samples. This significantly affects the preparation results of bulk polycrystalline potassium feldspar polymer samples. Therefore, neither natural potassium feldspar nor small-sized (no more than 6 mm) potassium feldspar 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 large-volume polycrystalline potassium feldspar 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 properties of large-volume framework-structured alkaline feldspar series oxygen-containing salt mineral aggregates—polycrystalline alkali metal or alkaline earth metal aluminosilicate 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 bulk polycrystalline potassium feldspar aggregates under high temperature and high pressure conditions, thereby filling the technical gap in the preparation of bulk experimental samples of high-density polycrystalline potassium feldspar aggregates under high temperature and high pressure conditions. This method aims to obtain bulk high-density polycrystalline potassium feldspar aggregate 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 alkaline feldspar series oxygen-containing salt mineral aggregates—polycrystalline alkali metal or alkaline earth metal aluminosilicate minerals and rocks—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] Technical solution of the present invention:

[0008] A method for preparing high-density bulk polycrystalline potassium feldspar polymers under high temperature and high pressure conditions, the method comprising: sealing potassium feldspar 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, and a graphite sealing cap was placed on it. Argon gas was selected as the pressure transmission medium. The temperature inside the cylinder sample chamber was raised to 1080 °C and the pressure was raised to 85.9 MPa using a multi-gradient hot isostatic pressing process of first increasing the pressure and then increasing the temperature. After holding the temperature and pressure for 8.1 hours, the temperature inside the cylinder sample chamber was reduced to 171 °C and the pressure was reduced to 51.9 MPa at a cooling rate of 15.15 °C / min and a depressurization rate of 0.57 MPa / min. Finally, the pressure was released and the temperature was cooled to room temperature to obtain polycrystalline potassium feldspar polymer.

[0009] The method for raising the temperature inside the cylinder sample chamber to 1080 °C and the pressure to 85.9 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 63.9 MPa within the temperature range of room temperature–600 °C using a heating rate of 18.2 °C / min and a pressurization rate of 0.66 MPa / min; raising the temperature inside the cylinder sample chamber to 900 °C and the pressure to 76.5 MPa within the temperature range of 600 °C–900 °C using a heating rate of 10 °C / min and a pressurization rate of 0.42 MPa / min within the temperature range of 900 °C–1080 °C using a heating rate of 7.2 °C / min and a pressurization rate of 0.38 MPa / min within the temperature range of 900 °C–1080 °C using a heating rate of 7.2 °C / min and a pressurization rate of 0.38 MPa / min within the temperature range of 1080 °C and 85.9 MPa within the temperature range of 1080 °C and 1080 °C.

[0010] The beneficial effects of this invention are:

[0011] 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 used an RD80×100‒2000–200 double 2000-type hot isostatic pressing equipment to prepare large-volume, highly dense polycrystalline potassium feldspar aggregate experimental samples under high temperature and high pressure conditions.

[0012] The initial raw material selected for this invention is gem-quality single-crystal potassium feldspar particles collected in the field, which are crushed into uniform mineral single-crystal 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 washing to ensure that the potassium feldspar sample powder is in a completely sealed environment protected by argon inert gas. The steel sheath containing the potassium feldspar sample powder is then 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, highly dense polycrystalline potassium feldspar aggregate. The prepared polycrystalline potassium feldspar 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.

[0013] The steel sheath used in the hot isostatic pressing (HIP) experiment of this invention has the following dimensions: 57.27 mm (outer diameter) × 85.25 mm (height) × 3 mm (wall thickness). This allows for the production of large-sized polycrystalline potassium feldspar polymer samples with diameters reaching 46.93 mm and heights reaching 69.45 mm. During the HIP experiment on the polycrystalline potassium feldspar 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 potassium feldspar 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 potassium feldspar sample powder and air within the sample chamber, effectively preventing redox reactions between the potassium feldspar 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 potassium feldspar polymer samples, potentially leading to the introduction of impurity ions.

[0014] This invention employs a multi-gradient hot isostatic pressing (HIP) process, first increasing pressure and then temperature, to prepare polycrystalline potassium feldspar polymer 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 potassium feldspar polymers. Furthermore, this invention's multi-gradient HIP process is not limited by the shape or size of the sample, allowing for the preparation of 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 conditions, this invention's multi-gradient HIP process can obtain polycrystalline potassium feldspar polymer experimental samples with near-theoretical density and extremely high sample strength.

[0015] 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 potassium feldspar aggregate experimental samples under conditions of 85.9 MPa and 1080 °C. These samples can be widely applied to high-pressure equipment with multiple large cavities, such as hydrothermal autoclaves, piston cylinder presses, and rotary shear friction testing machines, to simulate the solubility, friction coefficient, and shear stress of large-volume framework-structure alkaline feldspar series oxygen-containing salt mineral aggregates—polycrystalline alkali metal or alkaline earth metal aluminosilicate mineral rocks—under high temperature and high pressure conditions. 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

[0016] 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 potassium feldspar polymer are shown in the curves of temperature and pressure changes over time.

[0017] Figure 2 To obtain fine-grained potassium feldspar 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 potassium feldspar samples before hot isostatic pressing experiments were obtained using a high-magnification, high-precision Olympus SZX16 research-grade stereomicroscopic imaging platform.

[0018] Figure 3 This document presents the optical microscopic observation results of the surface morphology and particle size distribution of polycrystalline potassium feldspar polymer samples obtained from hot isostatic pressing experiments at 85.9 MPa and 1080 °C using the high-precision Olympus SZX16 research-grade stereomicroscopic imaging platform. Detailed Implementation

[0019] A method for preparing high-density bulk polycrystalline potassium feldspar polymers under high temperature and high pressure conditions, comprising:

[0020] Step 1: Use elongated elliptical potassium feldspar 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 potassium feldspar single crystal is 4.8 mm and the largest particle size is 10.9 mm. If the mineral grain size of potassium feldspar 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 potassium feldspar single crystals that do not contain other symbiotic / associated minerals or impurities. If the mineral grain size of potassium feldspar single crystal is too small, it is difficult to effectively separate potassium feldspar single crystals from hydrous layered aluminosilicate minerals, hydrous chain silicate minerals, island silicate minerals, spinel group minerals, dioxide minerals, framework silicate minerals, and hydrous cyclic borosilicate minerals of different compositions, such as muscovite, biotite, kaolinite, montmorillonite, amphibole, garnet, hematite, magnetite, rutile, nepheline, and tourmaline. Furthermore, this invention requires the selection of mineral single crystals with a relatively large weight, which will consume a lot of time and manpower.

[0021] Step 2: Place the selected potassium feldspar single crystal particles on an ultrasonic cleaner, and use acetone, alcohol and deionized water as cleaning solutions in sequence for ultrasonic cleaning for 24 minutes to remove impurities from the sample surface.

[0022] Step 3: Under the high-magnification, high-precision Olympus SZX16 research-grade stereomicroscopic imaging platform, 285 grams of potassium feldspar single crystal particles with complete crystal form, uniform color (flesh red), fresh surface, and no other impurity minerals were carefully selected to ensure that the initial sample of potassium feldspar single crystal particles had high purity before the hot isostatic pressing experiment under high temperature and high pressure conditions.

[0023] Step 4: Place the carefully selected potassium feldspar single crystal particles in a vacuum drying oven at 200 degrees Celsius for at least 26 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 potassium feldspar crystals, making it difficult to accurately weigh the initial sample of potassium feldspar single crystal particles during further grinding. If the temperature is too high, it may cause a decomposition reaction of the potassium feldspar single crystals, ultimately severely affecting the preparation effect of the hot isostatic pressing experimental sample under high temperature and high pressure conditions.

[0024] Step 5: Place the initial sample of potassium feldspar 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 potassium feldspar single crystal particles into mineral single crystal particles with a particle size of less than 2 mm. The purpose is to fully crush the sample to obtain potassium feldspar single crystal particles with a medium particle size (less than 2 mm).

[0025] Step 6: Place the sample on a high-efficiency Retsch disc vibratory mill (model: RS200), using a high-speed mode of 1410 rpm and setting the instrument's drive power to 1.5 kW. Grind the mineral single crystal particles into fine-grained potassium feldspar mineral powder with a particle size of 10.51 μm to 20.22 μm (see...). Figure 2 The amount of single-crystal potassium feldspar sample ground in a single cycle is 100 grams, and the grinding time is 8 minutes. Potassium feldspar powder within 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 effects. This is more conducive to forming a stronger bonding force between potassium feldspar powder particles during the hot isostatic pressing experiment of this invention, thereby greatly improving the compactness and density of the prepared fine-grained polycrystalline potassium feldspar polymer sample.

[0026] Step 7: Considering that the potassium feldspar sample powder with a relatively fine particle size is easy to absorb water in the air, it is placed in a paper sealed bag and dried in a vacuum drying oven at 90 degrees Celsius for 17 days to completely remove the adsorbed water on the surface of the sample powder.

[0027] Step 8: In the process of preparing polycrystalline potassium feldspar 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 potassium feldspar 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 1080 °C and the pressure of 85.9 °C required for the preparation of polycrystalline potassium feldspar 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 potassium feldspar 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 good welding performance.

[0028] 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 steel cladding for the potassium feldspar sample powder hot isostatic pressing test with dimensions of 57.27 mm (outer diameter) × 85.25 mm (height) × 3 mm (wall thickness).

[0029] 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 experiment of potassium feldspar sample powder.

[0030] Step 9: First, vacuum weld the sleeve and lower sealing cap of the steel cladding. Then, place the dried potassium feldspar sample powder inside the steel cladding. After a series of processes including compaction, vacuuming, high-temperature degassing, and high-temperature vacuum welding, the potassium feldspar sample powder is completely sealed in a vacuum of 100 kJ / L. –3 Pa is in the steel ladle sleeve.

[0031] Achieving such a low vacuum level within the steel-clad cavity requires at least 58 hours of evacuation, while simultaneously degassing the sample at 400 °C to ensure the potassium feldspar powder is completely in a sealed vacuum environment and that all moisture is removed. The potassium feldspar 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 potassium feldspar sample powder is fully compacted, which can ensure that a sufficient amount of potassium feldspar sample powder is sealed in the steel sleeve, which will help increase the density of the polycrystalline potassium feldspar polymer in the hot isostatic pressing experiment, thereby greatly improving the preparation effect of the final product bulk polycrystalline potassium feldspar polymer sample; (2) ensuring that the potassium feldspar sample powder is fully compacted, which can ensure the filling amount of potassium feldspar sample powder sealed in the steel sleeve, which will help enhance the compactness between potassium feldspar sample powder particles, effectively avoiding excessive deformation of the sample during the hot isostatic pressing experiment, thereby greatly improving the compactness of the final product bulk polycrystalline potassium feldspar 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 potassium feldspar sample powder sealed inside; (4) Under the condition of 400 °C, the potassium feldspar 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 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.

[0032] Step 10: Carefully place the steel sleeve containing the potassium feldspar 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 potassium feldspar 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.

[0033] 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 potassium feldspar 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.

[0034] 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.

[0035] 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 potassium feldspar 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.

[0036] Step 12: In this invention, argon is used as the pressure transmission medium. During the preparation of polycrystalline potassium feldspar 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. Since the initial material of this invention is a mineral powder that is difficult to mold, using argon as the inert gas pressure transmission medium and selecting 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 potassium feldspar polymer products.

[0037] 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 potassium feldspar polymers. The target pressure and temperature for the HIP experiment are 85.9 MPa and 1080 °C, respectively. If the selected target pressure and temperature are too low, the steel sheath used to seal the potassium feldspar sample powder during the HIP experiment will not be sufficiently compressed and effectively deformed. This makes it difficult to fully compact and sinter the sample, severely affecting the preparation of the experimental product—a bulk, high-density, and high-compact polycrystalline potassium feldspar polymer sample. Conversely, if the selected target pressure and temperature are too high, the polycrystalline framework structure of the alkali metal or alkaline earth metal aluminosilicate mineral—potassium feldspar—will decompose during the HIP experiment, severely impacting the prepared polycrystalline potassium feldspar polymer.

[0038] 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 potassium feldspar 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 molding experiments, high-temperature low-pressure empty furnace HIP molding experiments, and high-temperature high-pressure empty furnace HIP molding experiments of potassium feldspar sample powder, precise temperature and pressure calibration of the potassium feldspar sample chamber 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 potassium feldspar polymer HIP experiment. The formula for calculating the amount of argon gas consumed is as follows:

[0039] (1)

[0040] (2)

[0041] In the formula: parameter P target The target pressure for preparing polycrystalline potassium feldspar polymer samples under hot isostatic pressing (T) is based on the target temperature of the hot isostatic pressing experiment (T). target ) Perform the calculation; parameter Pbottle 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 potassium feldspar polymer sample under high temperature and high pressure conditions.

[0042] Step 13, vacuuming, filling with argon gas and cleaning the furnace, the purpose of which is to completely remove the air from the potassium feldspar 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.

[0043] 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 85.9 MPa and the target temperature of 1080 °C, at least 3 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 potassium feldspar sample chamber of the cylinder, so that the pre-pressurization of the sample chamber in the cylinder is pressurized to 44.1 MPa.

[0044] Step 15: Multi-gradient cylinder block heating and pressurization (see...) Figure 1Taking into account the target pressure and temperature for preparing polycrystalline potassium feldspar polymer samples in the hot isostatic pressing (HIP) experiment, as well as the safety, reliability, and durability of the graphite heating element itself, a multi-gradient cylinder heating and pressurization HIP experimental procedure was precisely controlled and automatically adjusted. The specific steps are as follows: In the temperature range of room temperature–600 °C, a heating rate of 18.2 °C / min and a pressurization rate of 0.66 MPa / min were used to raise the temperature in the cylinder sample chamber to 600 °C and the pressure to 63.9 MPa; in the medium temperature range of 600 °C–900 °C, a heating rate of 10 °C / min and a pressurization rate of 0.42 MPa / min were used to raise the temperature in the cylinder sample chamber to 900 °C and the pressure to 76.5 MPa; in the high temperature range of 900 °C–1080 °C, a heating rate of 7.2 °C / min and a pressurization rate of 0.38 MPa / min were used. A pressurization rate of MPa / min was used to raise the temperature inside the sample chamber to 1080 °C and the pressure to 85.9 MPa. As the temperature increased, the argon gas inside the sealed cylinder expanded dramatically. Since the cylinder volume remained constant, the argon gas volume was uniformly compressed, resulting in uniform high pressure. Ultimately, the pressure inside the sample chamber was maintained at 85.9 MPa, ensuring that the framework-structured alkali metal or alkaline earth metal aluminosilicate mineral – potassium feldspar – was fully compacted and cemented. The potassium feldspar sample powder was held at 85.9 MPa and 1080 °C for 8.1 hours. Potassium feldspar is a widely distributed and abundant non-water-soluble potassium mineral resource in the middle and lower crust of the Earth. It is mainly found in various igneous and metamorphic rocks, with a distinct geographical concentration. It is a low-symmetry monoclinic-triclinic crystal system mineral, exhibiting complex crystal morphology, obvious lattice preference orientation, and anisotropic physicochemical properties.

[0045] This invention employs a multi-gradient hot isostatic pressing (HIP) process, involving first increasing pressure and then increasing temperature, to prepare polycrystalline potassium feldspar polymer samples. The samples are held at a target pressure of 89.5 MPa and a target temperature of 1080 °C for 8.1 hours to ensure a sufficiently long holding time. If the holding time is too short, it is difficult to form strong bonding forces between the low-symmetry and diverse crystal morphologies of potassium feldspar mineral particles, and it is also difficult to overcome the influence of many unfavorable factors such as the preferred lattice orientation and anisotropy of potassium feldspar minerals, thus affecting the density and strength of the final bulk polycrystalline potassium feldspar polymer sample. Conversely, if the holding time is too long, although a highly dense and strong polycrystalline potassium feldspar polymer can be obtained, the final bulk polycrystalline potassium feldspar polymer sample will experience particle growth, uneven particle distribution, and recrystallization under prolonged high temperature and pressure, severely affecting the preparation effect and resulting in higher experimental costs.

[0046] Step 16: Cooling and depressurizing the cylinder. After the potassium feldspar sample powder was kept at a constant temperature and pressure of 85.9 MPa and 1080 °C for 8.1 hours, the temperature inside the sample chamber was reduced to 171 °C and the pressure to 51.9 MPa at a relatively slow and uniform cooling rate of 15.15 °C / min and a uniform depressurization rate of 0.57 MPa / min. The relatively slow and uniform cooling and depressurization rate was adopted primarily because if the cooling and depressurization rate were too fast, the internal stress of the steel sheath would not be fully released, leading to the direct fragmentation and damage of the large-volume polycrystalline potassium feldspar polymer sample, which would severely affect the preparation results.

[0047] This invention selects a sample chamber temperature of 171 °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.

[0048] 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.

[0049] 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 171 °C to room temperature (~25 °C).

[0050] Step 19: Set the control program for the hot isostatic pressing (HIP) equipment, open the furnace chamber, carefully remove the polycrystalline potassium feldspar polymer steel-clad workpiece sealed after the HIP experiment, and accurately measure the dimensions of the steel cladding after the HIP molding experiment: 52.93 mm (outer diameter) × 79.45 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 20.39%. This invention exhibits such a large volumetric shrinkage rate (η) of the steel sheath. 钢包套=20.39%), confirming that the steel sleeve used to seal and encapsulate the potassium feldspar sample powder was fully compressed and effectively deformed during the hot isostatic pressing experiment.

[0051] Step 20: Using a high-speed diamond saw blade cutter with a 1.0 mm thick diamond saw blade, the polycrystalline potassium feldspar polymer sample was carefully peeled from the steel ladle. The weight of the sample after the experiment was accurately measured to be 284 grams, and the tare weight of the steel ladle was 500 grams. This indicates that the weight of the potassium feldspar 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 potassium feldspar polymer sample obtained after the HIP experiment: 46.93 mm (diameter) × 69.45 mm (height). Comparing the initial potassium feldspar powder volume 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. 钾长石 Its calculation formula can be expressed as: η 钾长石 =(V 实验前钾长石 –V 实验后钾长石 ) / V 实验前钾长石 The volume shrinkage rate (η × 100%) is 22.67%. This invention exhibits such a large volume shrinkage rate (η × 100%) in potassium feldspar sample powder. 钾长石 =22.67%), confirming that during the hot isostatic pressing experiment, the potassium feldspar sample powder placed in the steel cladding was fully compacted and sintered under high temperature and high pressure conditions.

[0052] This invention utilizes an RD80×100‒2000–200 dual 2000-type hot isostatic pressing (HIP) apparatus to synthesize a polycrystalline potassium feldspar polymer from the initial material—a single-phase potassium feldspar single crystal—which is then crushed into medium-sized potassium feldspar single crystal particles, ground into fine potassium feldspar 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 potassium feldspar polymers are prepared. No other impurity phases are introduced during the entire preparation process, and the purity of the resulting polycrystalline potassium feldspar polymer samples can reach 100%.

[0053] Under epoxy resin inlay protection, a representative sample (19 mm × 19 mm cross-section) was cut from the polycrystalline potassium feldspar polymer workpiece, a product of hot isostatic pressing. 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 particle size distribution characteristics of the polycrystalline potassium feldspar polymer sample were tested. The test results (see...) Figure 3The polycrystalline potassium feldspar 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 as the pressure transfer 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 a uniform particle distribution, free from particle growth and recrystallization in the polycrystalline potassium feldspar polymer. In contrast 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 molding process that first increases pressure and then increases temperature, effectively overcoming numerous drawbacks of polycrystalline potassium feldspar polymer products, including particle growth, uneven particle distribution, and recrystallization.

[0054] High-resolution scanning electron microscopy was used to observe the microstructure of the polycrystalline potassium feldspar polymer sample obtained from the hot isostatic pressing experiment, and precise density tests were performed. The obtained polycrystalline potassium feldspar polymer 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 potassium feldspar polymer samples: (1) a higher pre-pressurization pressure (44.1 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 18.2 °C / min; in the medium-temperature zone (600 °C–900 °C), the heating rate is 10 °C / min; and in the high-temperature zone (900 °C–1080 °C), the heating rate is 7.2 °C / min; (3) a multi-gradient gradually decreasing cylinder pressure mode, namely, in the low-pressure zone of the HIP experiment (44.1 MPa–63.9 MPa), the pressure rate is 0.66 MPa / min; and in the medium-pressure zone (63.9 MPa–76.5 MPa), the pressure rate is 0.66 MPa / min. Under pressure of MPa, the pressurization rate is 0.42 MPa / min and under high pressure: 76.5 MPa–85.9 MPa, the pressurization rate is 0.38 MPa / min; (4) The relatively slow cylinder uniform cooling and depressurization mode, under pressure of 85.9 MPa–51.9 MPa, the uniform cooling rate and depressurization rate are 15.15 °C / min and 0.57 MPa / min, respectively; (5) The long-term constant temperature and constant pressure mode, at the highest temperature (1080 °C) and the highest pressure (85.9 MPa), ensures a sufficiently long constant temperature and constant pressure of 8.1 hours. All these optimized and improved hot isostatic pressing (HIP) experimental schemes can promote sufficient diffusion and particle aggregation between potassium feldspar 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 potassium feldspar polymer samples produced by HIP. In addition, this invention applies a higher temperature (1080 °C), a higher pressure (85.9 MPa), and a sufficiently long heat and pressure holding time (8.1 hours) to promote the formation of good bonding force between the particles of potassium feldspar sample powder, thereby greatly improving the density and strength of the polycrystalline potassium feldspar 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 prepared product that exist in the existing technology for synthesizing island silicate mineral single crystals by means of quasi-hydrostatic presses such as YJ-3000t and Kawai-1000t.

[0055] The Archimedes method using organically combined deionized water and the water intrusion method for porous, complex structures were employed to accurately measure the density of polycrystalline potassium feldspar polymer samples obtained from hot isostatic pressing experiments. The measured density of the polycrystalline potassium feldspar polymer was 2.58 g / cm³. 3 This density value falls exactly within the theoretical density of 2.54 g / cm³ for naturally collected potassium feldspar, as measured by geologists. 3 -2.59 g / cm 3 Within the specified range, the obtained bulk polycrystalline potassium feldspar polymer samples exhibited extremely high density. The high density of these polycrystalline potassium feldspar polymer products is highly correlated with the optimized molding process employed during this hot isostatic pressing experiment, including pretreatment of the potassium feldspar 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 potassium feldspar sample powder raw materials, namely fine-grained potassium feldspar mineral powder with a particle size of 10.51 micrometers to 20.22 micrometers, is performed. Potassium feldspar in this particle size range has a large specific surface area, which significantly increases the contact area between sample particles, making it more conducive to the formation of strong and good cementing force, thereby greatly improving the density of the prepared polycrystalline potassium feldspar polymer sample. A 3 mm thick 20# low-carbon steel continuous casting slab is used 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 uniformly transferred to the potassium feldspar sample powder enclosed within it, thus greatly improving the density of the prepared polycrystalline potassium feldspar polymer sample. An optimized and improved cooling and depressurization hot isostatic pressing process is adopted, especially the relatively slow and uniform cylinder depressurization mode (pressurization rate: 0.38 MPa / min – 0.66 MPa / min; depressurization rate: 0.57 MPa / min). (MPa / min) ensures that the internal stress of large-volume polycrystalline potassium feldspar 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 potassium feldspar polymer sample. A high-temperature degassing optimization molding process at 400 °C is employed, sealing the potassium feldspar sample powder in a steel sleeve and subjecting it to high-temperature vacuum degassing at 400 °C to minimize residual gas, thereby obtaining polycrystalline potassium feldspar 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 bulk polycrystalline potassium feldspar polymers under high temperature and high pressure conditions, characterized in that: The method includes: sealing potassium feldspar sample powder in a vacuum chamber with a vacuum degree of 10. –3 The steel cladding was placed in the graphite furnace cylinder of the high-pressure vessel of the hot isostatic pressing equipment, and a graphite sealing cap was placed on it. Argon gas was selected as the pressure transmission medium. The temperature inside the cylinder sample chamber was raised to 1080 °C and the pressure was raised to 85.9 MPa using a multi-gradient hot isostatic pressing process of first increasing the pressure and then increasing the temperature. After holding the temperature and pressure for 8.1 hours, the temperature inside the cylinder sample chamber was reduced to 171 °C and the pressure was reduced to 51.9 MPa at a cooling rate of 15.15 °C / min and a depressurization rate of 0.57 MPa / min. Finally, the pressure was released and the temperature was cooled to room temperature to obtain polycrystalline potassium feldspar polymer.

2. The method for preparing high-density bulk polycrystalline potassium feldspar polymer under high temperature and high pressure conditions according to claim 1, characterized in that: Methods for preparing potassium feldspar sample powder include: Step 1: Select elongated elliptical potassium feldspar single crystal mineral particles with a minimum particle size of 4.8 mm and a maximum particle size of 10.9 mm as the initial sample; Step 2: Place the selected potassium feldspar single crystal mineral particles on an ultrasonic cleaner, and use acetone, alcohol and deionized water as cleaning solutions in sequence for ultrasonic cleaning for 24 minutes. Step 3: Select 285 grams of potassium feldspar single crystal particles that are complete in crystal form, uniform in color (flesh red), fresh in surface, and free of impurities. Step 4: Place the selected potassium feldspar single crystal particles in a vacuum drying oven at 200 degrees Celsius and dry for at least 26 hours; Step 5: Crush the dried potassium feldspar single crystal particles into mineral single crystal particles with a particle size of less than 2 mm. Step 6: Grind the mineral single crystal particles into potassium feldspar mineral powder with a particle size of 10.51 micrometers to 20.22 micrometers; Step 7: Pack the potassium feldspar mineral powder into a sealed paper bag and dry it in a vacuum drying oven at 90 degrees Celsius for 17 days.

3. The method for preparing high-density bulk polycrystalline potassium feldspar polymer under high temperature and high pressure conditions according to claim 1, characterized in that: The manufacturing methods for steel bladder sleeves 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 coiled into a steel strip coil by a coiler, and then undergoes three rolling processes and multiple hot rolling processes including edge trimming to finally obtain a steel cladding sleeve with dimensions of 57.27 mm (outer diameter) × 85.25 mm (height) × 3 mm (wall thickness). Select a continuous casting slab of No. 20 low-carbon steel with a wall thickness of 3 mm, and use the same multiple hot rolling process to prepare the upper sealing cap and lower sealing cap of the steel cladding sleeve. The sleeve, upper sealing cap and lower sealing cap are welded together by high temperature vacuum welding to prepare a complete steel cladding sleeve.

4. The method for preparing high-density bulk polycrystalline potassium feldspar polymer under high temperature and high pressure conditions according to claim 1, characterized in that: The potassium feldspar sample powder was sealed in a vacuum of 10. –3 The method for sealing the potassium feldspar sample powder in a steel cladding includes: first, vacuum welding the sleeve and lower sealing cap of the steel cladding; then, placing the dried potassium feldspar sample powder inside the steel cladding; and finally, compacting, vacuuming, high-temperature degassing, and high-temperature vacuum welding to completely seal the potassium feldspar sample powder under a vacuum of 10... –3 The sample was placed in a steel bladder containing Pa; a vacuum was applied for at least 58 hours, and the sample was simultaneously degassed at 400 °C.

5. The method for preparing high-density bulk polycrystalline potassium feldspar polymer under high temperature and high pressure conditions 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: (1)； (2)； In the formula: parameter P target The target pressure for preparing polycrystalline potassium feldspar polymer 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 cylinders with 99.999% argon purity required to complete a single hot isostatic pressing experiment on a polycrystalline potassium feldspar polymer sample under high temperature and high pressure conditions.

6. The method for preparing high-density bulk polycrystalline potassium feldspar polymer under high temperature and high pressure conditions according to claim 1, characterized in that: Argon gas filling methods 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. Evacuate until the vacuum level instrument's digital display 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 three times to completely remove all the air from the sample chamber; Step 14, Pre-pressurization of the sample chamber: Prepare at least 3 argon cylinders with an internal pressure of 15 MPa; evenly fill the argon cylinders with an internal pressure of 15 MPa into the high-pressure pressurization tank of the hot isostatic pressing equipment, and then freely fill the cylinder with 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 potassium feldspar sample chamber of the cylinder, so that the sample chamber in the cylinder is pre-pressurized to 44.1 MPa.

7. The method for preparing high-density bulk polycrystalline potassium feldspar polymer 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 1080 °C and the pressure to 85.9 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 63.9 MPa within the temperature range of room temperature–600 °C using a heating rate of 18.2 °C / min and a pressurization rate of 0.66 MPa / min; raising the temperature inside the cylinder sample chamber to 900 °C and the pressure to 76.5 MPa within the temperature range of 600 °C–900 °C using a heating rate of 10 °C / min and a pressurization rate of 0.42 MPa / min; and raising the temperature inside the cylinder sample chamber to 1080 °C and the pressure to 85.9 MPa within the temperature range of 900 °C–1080 °C using a heating rate of 7.2 °C / min and a pressurization rate of 0.38 MPa / min.

8. The method for preparing high-density bulk polycrystalline potassium feldspar polymer under high temperature and high pressure conditions according to claim 1, characterized in that: Methods for obtaining polycrystalline potassium feldspar polymers by depressurization and cooling to room temperature include: Step 17, Depressurization: First, let the argon gas in the cylinder of the hot isostatic press 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 release the gas in the cylinder and discharge all the residual gas through the pipeline. 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 171 °C to room temperature. Step 19: Set the control program for the hot isostatic pressing equipment, open the furnace, and remove the ladle sleeve after the hot isostatic pressing experiment. Step 20: Use a diamond saw blade cutter to peel the polycrystalline potassium feldspar polymer sample from the steel sheath.

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