Siliceous furnace lining material for smelting environment with high scrap ratio and preparation method of siliceous furnace lining material

Abstract

The invention relates to a siliceous furnace lining material for a smelting environment with a high scrap ratio and a preparation method of the siliceous furnace lining material. The siliceous furnace lining material comprises the following components in parts by mass: 30-40 parts of selected microcrystalline silica tailings, 30-40 parts of fused quartz, 20-35 parts of spherical zirconium composite silica powder and 1-2 parts of a sintering aid. Wherein the SiO2 content of the selected microcrystalline silica tailings is greater than or equal to 99.5%. According to the present invention, the 99.5% selected microcrystalline silica tailings are adopted as the aggregate, such that the impurity reaction sites can be effectively reduced, the refractoriness can be increased to more than or equal to 1720 DEG C, and the spherical zirconium composite silica micro-powder is adopted as the matrix so as to effectively inhibit the cracking of the furnace lining and improve the fluidity of the slurry; boric acid in the sintering aid can promote low-temperature sintering to form a glass-phase combined phase. According to the siliceous furnace lining material for the smelting environment with the high scrap ratio, the sintering layer is specifically composed of the cristobalite phase and the silicon zirconium glass phase, and the siliceous furnace lining of an intermediate frequency furnace can be better protected.

Description

Technical Field

[0001] This invention relates to the field of silicon material technology, and in particular to a silicon furnace lining material for high scrap ratio smelting environments and its preparation method. Background Technology

[0002] Medium-frequency induction furnaces are widely used high-temperature equipment in the field of metal smelting. The furnace lining material is usually in direct contact with high-temperature furnaces or carbon bricks. When the furnace is working, it must withstand high temperatures. An ideal furnace lining material needs to have a low thermal conductivity, so as to reduce the hot surface temperature of the carbon bricks or reduce the heat loss of the furnace. In high-temperature furnaces and other thermal equipment, furnace lining material is a common refractory material. The quality of the furnace lining determines the smelting quality and production cost of the medium-frequency induction furnace.

[0003] Currently, the furnace lining materials for medium-frequency induction furnaces used in smelting carbon steel are mostly made of quartz as the main raw material, mixed with boric acid as a sintering agent. With the increasing amount of scrap steel, more and more foundries are introducing scrap steel to replace part of the pig iron in the casting process, and are gradually increasing the scrap steel ratio. Impurities such as Al2O3 and CaO in scrap steel react with SiO2 to form anorthite (CaAl2Si2O8, melting point 1550 ℃) or cordierite (Mg2Al4Si5O18, melting point 1450 ℃), forming a liquid phase that accelerates erosion and leads to poor resistance to abnormal erosion of the furnace lining material. Quartz can undergo crystal transformation at high temperatures, which also reduces the erosion resistance of the furnace lining material. Ordinary silica powder particles are irregular and cannot completely fill the gaps between aggregates (apparent porosity > 18%), and low-viscosity slag can easily penetrate into the deep layer of the furnace lining, leading to uncontrolled penetration. Polycrystalline silica undergoes phase transformation at high temperatures, causing volume expansion, and microcracks propagate during cooling, leading to thermal shock cracks. Impurities hinder the transformation of SiO2 into cristobalite, and local unsintered areas become erosion channels, resulting in uneven sintered layers. Although existing technologies pay attention to the matching of furnace charge, due to the large variety of scrap steel, such as pig iron blocks, modified pig iron, steel scrap, iron scrap, internally recycled scrap steel, and externally purchased scrap steel, the volume and weight of the furnace charge vary greatly. With limited scrap steel storage space and a fast production pace, it is difficult for staff to achieve a reasonable matching of the charge. This can easily lead to large fluctuations in slag volume and unstable temperature, making it difficult to effectively protect the furnace lining material.

[0004] Therefore, existing medium-frequency furnace linings generally use polycrystalline quartz sand (SiO2 ≤ 98.5%) with boric acid sintering agent. Due to impurities such as Al2O3 and CaO in the scrap steel reacting with SiO2 to form anorthite (CaAl2Si2O8, melting point 1550 ℃) or cordierite (Mg2Al4Si5O18, melting point 1450 ℃), a liquid phase is formed, accelerating erosion and resulting in poor resistance to abnormal erosion of the lining. Simultaneously, the irregular particle size of ordinary silica powder cannot completely fill the aggregate gaps, and low-viscosity molten slag easily penetrates deep into the lining, potentially leading to uncontrolled lining penetration. Furthermore, polycrystalline silica undergoes a quartz phase transformation at high temperatures, resulting in significant volume expansion. During cooling, microcracks propagate, impurities hinder the transformation of SiO2 into cristobalite, and unsintered areas become erosion channels, easily leading to thermal shock cracks and uneven sintering layers. Summary of the Invention

[0005] Therefore, it is necessary to provide a silicon furnace lining material and its preparation method that can better protect the silicon furnace lining of medium frequency furnaces in high scrap steel ratio smelting environments, in order to address the above-mentioned technical problems.

[0006] The first aspect of this invention provides a siliceous furnace lining material for high scrap ratio smelting environments, comprising: 30-40 parts by weight of selected microcrystalline silica tailings, 30-40 parts by weight of fused silica, 20-35 parts by weight of spherical zircon composite silica powder, and 1-2 parts by weight of sintering aids. The selected microcrystalline silica tailings have a SiO2 content of ≥99.5%.

[0007] In one embodiment, the grain size of the selected microcrystalline silica tailings is less than or equal to 10 μm.

[0008] In one embodiment, the selected microcrystalline silica tailings have a particle size range of 1-3 mm.

[0009] In one embodiment, the SiO2 content of the fused silica is greater than or equal to 99.5%.

[0010] In one embodiment, the fused silica has a particle size of 0.1-1 mm.

[0011] In one embodiment, the ZrO2 content in the spherical zirconium composite silicon micropowder is 15±2%, and the D50 of the spherical zirconium composite silicon micropowder is 0.2μm, and the sphericity is greater than or equal to 0.9.

[0012] In one embodiment, the sintering aid is boric acid or boric anhydride.

[0013] In one embodiment, the boric acid or boric anhydride has a purity of 99% or higher and a particle size of 45 μm or lower.

[0014] The second aspect of this invention provides a method for preparing a siliceous furnace lining material for a high scrap ratio smelting environment, for preparing the siliceous furnace lining material for a high scrap ratio smelting environment as described in any one of the first aspects, the method comprising: 30-40 parts by weight of selected microcrystalline silica tailings, 30-40 parts by weight of fused silica, 20-35 parts by weight of spherical zircon composite silica powder and 1-2 parts by weight of sintering aid are added to a mixer and mixed thoroughly to obtain siliceous furnace lining material. The selected microcrystalline silica tailings have a SiO2 content of ≥99.5%.

[0015] In one embodiment, the grain size of the selected microcrystalline silica tailings is less than or equal to 10 μm, and the particle size range of the selected microcrystalline silica tailings is 1-3 mm. The SiO2 content of the fused silica is greater than or equal to 99.5%, and the particle size of the fused silica is 0.1-1 mm; The ZrO2 content in the spherical zirconium composite silicon micropowder is 15±2%, and the D50 of the spherical zirconium composite silicon micropowder is 0.2μm, and the sphericity is greater than or equal to 0.9. The sintering aid is boric acid or boric anhydride, wherein the purity of the boric acid or boric anhydride is greater than or equal to 99%, and the particle size of the boric acid or boric anhydride is less than or equal to 45 μm.

[0016] The aforementioned silica furnace lining material for high scrap ratio smelting environments and its preparation method involve thoroughly mixing 30-40 parts by mass of selected microcrystalline silica tailings with a SiO2 content of ≥99.5%, 30-40 parts by mass of fused silica, 20-35 parts by mass of spherical zirconium composite silica powder, and 1-2 parts by mass of sintering aids in a mixer. Using 99.5% selected microcrystalline silica tailings as aggregate effectively reduces impurity reaction sites and increases the refractoriness to ≥1720 °C. Simultaneously, using spherical zirconium composite silica powder as a matrix effectively inhibits furnace lining cracking and improves slurry fluidity. Furthermore, boric acid in the sintering aid promotes low-temperature sintering, forming a glassy composite phase. Experiments show that, regarding slag penetration, spherical zirconium composite silicon micropowder, as a matrix, can fill pores to an apparent porosity of ≤15%, reducing penetration depth by 40%. Regarding the problem of cooling phase transformation cracking, the zirconium composite silicon micropowder transforms from a tetragonal phase to a monoclinic phase during cooling, resulting in volume expansion that compensates for the thermal shock of quartz phase transformation shrinkage. The slow cooling phase transformation expansion (+3~5%) of the zirconium silicon micropowder in the 1000-1170 ℃ range can offset 60-70% of the quartz shrinkage stress, reducing the peak thermal stress by 59%. The added spherical micropowder improves fluidity, increases the uniformity of molding density, and significantly improves the consistency of sintered layer thickness. The specific composition of the sintered layer is "cristobalite phase and zirconium silicon glass phase." Therefore, this invention can better protect the silicon lining of the medium-frequency furnace. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the ZrO2 action mechanism provided by the present invention; Figure 2 This is a schematic diagram of the sintered layer gradient structure provided by the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this specification are for illustrative purposes only and do not represent the only possible implementation.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0022] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0023] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0024] The following is combined with Figures 1-2 This invention describes a silica furnace lining material for high scrap ratio smelting environments and its preparation method.

[0025] like Figure 1 As shown, in one embodiment, a silica furnace lining material for high scrap ratio smelting environments comprises the following components: 30-40 parts by weight of selected microcrystalline silica tailings, 30-40 parts by weight of fused silica, 20-35 parts by weight of spherical zircon composite silica powder, and 1-2 parts by weight of sintering aids.

[0026] Among them, the SiO2 content of the selected microcrystalline silica tailings is greater than or equal to 99.5%, the grain size of the selected microcrystalline silica tailings is less than or equal to 10μm, and the particle size range of the selected microcrystalline silica tailings is 1-3mm; the SiO2 content of the fused silica is greater than or equal to 99.5%, and the particle size of the fused silica is 0.1-1mm; the ZrO2 content in the spherical zirconium composite silica powder is 15±2%, and the D50 of the spherical zirconium composite silica powder is 0.2μm, and the sphericity is greater than or equal to 0.9; the sintering aid is boric acid or boric anhydride, the purity of boric acid or boric anhydride is greater than or equal to 99%, and the particle size of boric acid or boric anhydride is less than or equal to 45μm.

[0027] This invention provides a silica furnace lining material for high scrap ratio smelting environments. During the high scrap ratio smelting process, the intermediate reaction and reaction products at the low-temperature stage (300-1000 ℃) are as follows: 300-450 ℃: The intermediate product is boron anhydride (B2O3), and the chemical reaction equation is: 2H3BO3 → B2O3+3H2O↑. At this time, it is in an amorphous glassy state. 700-900 ℃: The intermediate product is a borosilicate premelt, and the chemical reaction equation is: B2O3 + SiO2 → xB2O3·ySiO2 (amorphous).

[0028] The intermediate reaction and reaction products during the high-temperature stage (1000-1450 ℃) are as follows: 1200-1300 ℃: The product at this temperature is mainly cristobalite, which is transformed from tridymite; 1350-1450 ℃: At this temperature, ZrO2-SiO2 liquid phase sintering mainly occurs, with the reaction: SiO2 + ZrO2 → ZrSiO4 (trace amount), forming glass-encapsulated t-ZrO2 grains.

[0029] The aforementioned silica furnace lining material for high scrap ratio smelting environments uses 99.5% selected microcrystalline silica tailings as aggregate, which effectively reduces impurity reaction sites and increases refractoriness to ≥1720 ℃. Simultaneously, the use of spherical zirconium composite silica powder as a matrix effectively inhibits furnace lining cracking and improves slurry fluidity. Furthermore, boric acid in the sintering aid promotes low-temperature sintering, forming a glassy composite phase. Experiments show that, for slag penetration, spherical zirconium composite silicon micropowder, as a matrix, can fill pores to an apparent porosity of ≤15%, reducing penetration depth by 40%. Regarding the problem of cooling phase transformation cracking, the zirconium composite silicon micropowder transforms from a tetragonal phase to a monoclinic phase during cooling, resulting in volume expansion that compensates for the thermal shock of quartz phase transformation shrinkage. The slow cooling phase transformation expansion (+3~5%) of zirconium silicon micropowder in the 1000-1170 ℃ range can offset 60-70% of quartz shrinkage stress, reducing the peak thermal stress by 59%. The added spherical micropowder improves fluidity, increases the uniformity of molding density, and significantly improves the consistency of sintered layer thickness. The specific composition of its sintered layer is "cristobalite phase and silicon zirconium glass phase." Therefore, this silicon furnace lining material can better protect the silicon furnace lining of the medium-frequency furnace.

[0030] In one embodiment, a method for preparing a silica-based furnace lining material for a high scrap ratio smelting environment includes the following steps: Step S110: 30-40 parts by weight of selected microcrystalline silica tailings, 30-40 parts by weight of fused silica, 20-35 parts by weight of spherical zircon composite silica powder, and 1-2 parts by weight of sintering aid are added to a mixer and thoroughly mixed to obtain a siliceous furnace lining material.

[0031] Among them, the SiO2 content of the selected microcrystalline silica tailings is greater than or equal to 99.5%, the grain size of the selected microcrystalline silica tailings is less than or equal to 10μm, and the particle size range of the selected microcrystalline silica tailings is 1-3mm; the SiO2 content of the fused silica is greater than or equal to 99.5%, and the particle size of the fused silica is 0.1-1mm; the ZrO2 content in the spherical zirconium composite silica powder is 15±2%, and the D50 of the spherical zirconium composite silica powder is 0.2μm, and the sphericity is greater than or equal to 0.9; the sintering aid is boric acid or boric anhydride, the purity of boric acid or boric anhydride is greater than or equal to 99%, and the particle size of boric acid or boric anhydride is less than or equal to 45μm.

[0032] The aforementioned method for preparing a silica-based furnace lining material for high scrap ratio smelting environments involves thoroughly mixing 30-40 parts by mass of selected microcrystalline silica tailings with a SiO2 content of ≥99.5%, 30-40 parts by mass of fused silica, 20-35 parts by mass of spherical zirconium composite silica powder, and 1-2 parts by mass of sintering aids in a mixer. Using 99.5% selected microcrystalline silica tailings as aggregate effectively reduces impurity reaction sites and increases the refractoriness to ≥1720 °C. Simultaneously, using spherical zirconium composite silica powder as a matrix effectively inhibits furnace lining cracking and improves slurry fluidity. Furthermore, boric acid in the sintering aids promotes low-temperature sintering, forming a glassy composite phase. Experiments show that, regarding slag penetration, spherical zirconium composite silicon micropowder, as a matrix, can fill pores to an apparent porosity of ≤15%, reducing penetration depth by 40%. Regarding cooling phase transformation cracking, the zirconium composite silicon micropowder transforms from a tetragonal phase to a monoclinic phase during cooling, resulting in volume expansion that compensates for the thermal shock of quartz phase transformation shrinkage. The slow cooling phase transformation expansion (+3~5%) of zirconium silicon micropowder in the 1000-1170 ℃ range can offset 60-70% of quartz shrinkage stress, reducing peak thermal stress by 59%. The added spherical micropowder improves fluidity, increases molding density uniformity, and significantly enhances the consistency of sintered layer thickness. The sintered layer is specifically composed of "cristobalite phase and zirconium silicon glass phase." Therefore, the silicon furnace lining material prepared by this method can better protect the silicon furnace lining of the medium-frequency furnace.

[0033] Combination Figure 1 and Figure 2 As shown, the following examples 1-3 further illustrate the siliceous furnace lining material for high scrap ratio smelting environments provided by the present invention and its preparation method: Example

[0034] The main aggregate uses microcrystalline silica (SiO2) ≥ 99.5%, with a particle size of 1-3 mm (35% by mass), and grain size ≤ 10 μm. Low grain boundary defects delay phase transformation, reducing the reactivity of CaO / Al2O3 and improving the material's refractoriness. Medium-particle filler uses 0.1-1 mm fused silica, accounting for 30% by mass. The matrix uses spherical zirconium composite silica powder: ZrO2 content 15±2%, D50 = 0.2 μm, sphericity ≥ 0.9 submicron, filling pores, accounting for 35% by mass. Upon cooling, the ZrO2 phase transformation expansion (3-5%) can compress cracks (mechanism as follows). Figure 1 As shown in the figure, to suppress the problems of slag penetration and cooling phase transformation, the added spherical zirconium composite silicon micropowder can improve fluidity, increase the uniformity of molding density, and significantly improve the consistency of sintered layer thickness; the binder is boric acid with a mass ratio of 1%. After the above raw materials are prepared, they are mixed in a mixer for 30 minutes. After mixing, the silicon furnace lining material of the present invention for high scrap steel ratio smelting environment is obtained. Example

[0035] The main aggregate uses microcrystalline silica (SiO2) ≥ 99.5%, with a particle size of 1-3 mm (40% by mass), and grain size ≤ 10 μm. Low grain boundary defects delay phase transformation, reducing the reactivity of CaO / Al2O3 and improving the material's refractoriness. Medium-particle filler uses 0.1-1 mm fused silica, accounting for 30% by mass. The matrix uses spherical zirconium composite silica powder: ZrO2 content 15±2%, D50 = 0.2 μm, sphericity ≥ 0.9 submicron, filling pores, accounting for 29% by mass. Upon cooling, the ZrO2 phase transformation expansion (3-5%) can compress cracks (mechanism as follows). Figure 1 As shown in the figure, to suppress the problems of slag penetration and cooling phase transformation, the added spherical zirconium composite silicon micropowder can improve fluidity, increase the uniformity of molding density, and significantly improve the consistency of sintered layer thickness; the binder is boric acid with a mass ratio of 1%. After the above raw materials are prepared, they are mixed in a mixer for 30 minutes. After mixing, the silicon furnace lining material of the present invention for high scrap steel ratio smelting environment is obtained. Example

[0036] The main aggregate uses microcrystalline silica (SiO2) ≥ 99.5%, with a particle size of 1-3 mm (30% by mass), and grain size ≤ 10 μm. Low grain boundary defects delay phase transformation, reducing the reactivity of CaO / Al2O3 and improving the material's refractoriness. Medium-particle filler uses 0.1-1 mm fused silica, accounting for 40% by mass. The matrix uses spherical zirconium composite silica powder: ZrO2 content 15±2%, D50 = 0.2 μm, sphericity ≥ 0.9 submicron, filling pores, accounting for 20% by mass. Upon cooling, the ZrO2 phase transformation expansion (3-5%) can compress cracks (mechanism as follows). Figure 1 As shown in the figure, to suppress the problems of slag penetration and cooling phase transformation, the added spherical zirconium composite silicon micropowder can improve fluidity, increase the uniformity of molding density, and significantly improve the consistency of sintered layer thickness; the binder is boric acid with a mass ratio of 2%. After the above raw materials are prepared, they are mixed in a mixer for 30 minutes. After mixing, the silicon furnace lining material of the present invention for high scrap steel ratio smelting environment is obtained.

[0037] High-purity natural silica resources suitable for preparing siliceous furnace linings are becoming increasingly scarce. Furthermore, the production of industrial silica generates a large amount of silica tailings that are not effectively utilized, resulting in significant waste of silica resources and extremely high tailings treatment costs. This invention employs advanced artificial intelligence-based mineral processing to precisely extract high-grade ore raw materials from silica tailings, using them as raw materials for preparing high-performance siliceous furnace linings. This not only greatly improves resource utilization but also creates greater economic and social benefits.

[0038] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0039] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A siliceous furnace lining material for high scrap ratio smelting environments, characterized in that, include: 30-40 parts by weight of selected microcrystalline silica tailings, 30-40 parts by weight of fused silica, 20-35 parts by weight of spherical zircon composite silica powder, and 1-2 parts by weight of sintering aids. The selected microcrystalline silica tailings have a SiO2 content of ≥99.5%.

2. The siliceous furnace lining material for high scrap ratio smelting environments according to claim 1, characterized in that, The selected microcrystalline silica tailings have a grain size of less than or equal to 10 μm.

3. A siliceous furnace lining material for high scrap ratio smelting environments according to claim 2, characterized in that, The selected microcrystalline silica tailings have a particle size range of 1-3 mm.

4. A siliceous furnace lining material for high scrap ratio smelting environments according to claim 1, characterized in that, The SiO2 content of the fused silica is greater than or equal to 99.5%.

5. A siliceous furnace lining material for high scrap ratio smelting environments according to claim 4, characterized in that, The particle size of the fused silica is 0.1-1 mm.

6. A siliceous furnace lining material for high scrap ratio smelting environments according to claim 1, characterized in that, The ZrO2 content in the spherical zirconium composite silicon micropowder is 15±2%, and the D50 of the spherical zirconium composite silicon micropowder is 0.2μm, and the sphericity is greater than or equal to 0.

9.

7. A siliceous furnace lining material for high scrap ratio smelting environments according to claim 1, characterized in that, The sintering aid is boric acid or boric anhydride.

8. A siliceous furnace lining material for high scrap ratio smelting environments according to claim 7, characterized in that, The purity of the boric acid or boric anhydride is greater than or equal to 99%, and the particle size of the boric acid or boric anhydride is less than or equal to 45 μm.

9. A method for preparing a siliceous furnace lining material for high scrap ratio smelting environments, characterized in that, The method for preparing a siliceous furnace lining material for high scrap ratio smelting environments as described in any one of claims 1 to 8 comprises: 30-40 parts by weight of selected microcrystalline silica tailings, 30-40 parts by weight of fused silica, 20-35 parts by weight of spherical zircon composite silica powder and 1-2 parts by weight of sintering aid are added to a mixer and mixed thoroughly to obtain siliceous furnace lining material. The selected microcrystalline silica tailings have a SiO2 content of ≥99.5%.

10. A method for preparing a siliceous furnace lining material for a high scrap ratio smelting environment according to claim 9, characterized in that, The selected microcrystalline silica tailings have a grain size of less than or equal to 10 μm and a particle size range of 1-3 mm. The SiO2 content of the fused silica is greater than or equal to 99.5%, and the particle size of the fused silica is 0.1-1 mm; The ZrO2 content in the spherical zirconium composite silicon micropowder is 15±2%, and the D50 of the spherical zirconium composite silicon micropowder is 0.2μm, and the sphericity is greater than or equal to 0.

9. The sintering aid is boric acid or boric anhydride, wherein the purity of the boric acid or boric anhydride is greater than or equal to 99%, and the particle size of the boric acid or boric anhydride is less than or equal to 45 μm.

Images