A low thermal expansion mineral casting and its preparation method

Abstract

The present invention belongs to the field of mineral castings, and particularly relates to a low thermal expansion mineral casting and a preparation method thereof. The raw material components of the mineral casting provided by the present invention include: 35-70 wt% of silanized mineral aggregate, 20-60 wt% of negative thermal expansion additive, and 5-15 wt% of binder; the negative thermal expansion additive is β-eucryptite; the components of the binder are epoxy resin and curing agent. By embedding the negative thermal expansion material - β-eucryptite in the mineral casting, the present invention reduces the thermal expansion coefficient of the mineral casting, improves the manufacturing precision, and the obtained mineral casting has good isotropy, and the deformation amounts in all directions are uniform, and it has wide applications in machine tool manufacturing, construction or transportation.

Description

Technical Field

[0001] The present invention belongs to the field of mineral castings, and particularly relates to a low thermal expansion mineral casting and a preparation method thereof. Background Art

[0002] As an important equipment for industrial production, the performance of machine tools plays a crucial role in the quality and production efficiency of products. Due to the intensification of market competition and the continuous upgrading of digital production technologies, automation, adaptability, integration, and intelligence have become increasingly important in modern manufacturing. With the continuous development of the equipment manufacturing industry towards precision, ultra-precision, high speed, and high efficiency, the vibration generated during the processing has become a key factor affecting the dimensional accuracy and surface quality of workpieces, requiring machine tools to have better static and dynamic performance. The requirements for precision in large ultra-precision measuring instruments and processing equipment have reached the nanometer level or even higher.

[0003] Currently, the materials commonly used for manufacturing the platforms of processing equipment and measuring instruments are cast iron and marble. However, the low seismic resistance of cast iron makes it difficult to be used in the ultra-precision field. At the same time, the high energy consumption and pig iron consumption during the production process of cast iron also limit its application. And the difficulty of processing marble into complex shapes and the gradual consumption of natural stone also make it difficult to be used on a large scale.

[0004] Due to its characteristics such as high strength, high stiffness, and good damping performance, mineral castings have gradually attracted people's attention. Compared with cast iron, the bed of a processing equipment made of mineral castings can improve the seismic resistance by 1.4 times, and the price can be about 15 times cheaper. When preparing a measuring platform of the same volume, compared with cast iron, using mineral castings will reduce carbon emissions by 77.80%. Compared with cast iron, mineral castings can integrate components such as sensors and cooling channels. Mineral castings have excellent wear resistance and corrosion resistance, which can greatly extend the service life of machine tools. At the same time, mineral castings can be freely shaped into various shapes and sizes to meet the design requirements of different machine tools. Mineral castings do not require the stone to have a complete shape, and small stones during the mining process can be used. It can be cast into shape like cast iron. Using mineral castings in processing equipment helps to improve the processing accuracy of the equipment, reduce energy costs, and improve environmental friendliness.

[0005] In the ultra-precision field, the change in material expansion caused by heat sources will lead to a decrease in precision. However, the resin component of mineral castings brings a relatively high coefficient of thermal expansion, making it difficult to be used in more precise processing equipment. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a low thermal expansion mineral casting and a preparation method thereof. The mineral casting provided by the present invention has a relatively low coefficient of thermal expansion.

[0007] The present invention provides a low thermal expansion mineral casting, and the raw material components include: 35-70 wt% of silanized mineral aggregate, 20-60 wt% of negative thermal expansion additive, and 5-15 wt% of binder; the negative thermal expansion additive is β - lithium feldspathoid; the components of the binder are epoxy resin and curing agent.

[0008] Preferably, the silanized mineral aggregate includes mineral aggregate and silanizing reagent attached to the surface of the mineral aggregate. The mineral aggregate is one or more of fused quartz sand, granite, and marble, and the silanizing reagent is one or more of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-mercaptopropyltriethoxysilane.

[0009] Preferably, the mass ratio of the mineral aggregate to the silanizing reagent in the silanized mineral aggregate is 100:(1-5).

[0010] Preferably, the particle size of the silanized mineral aggregate is 0.05-5 mm.

[0011] Preferably, the particle size of the silanized mineral aggregate conforms to continuous gradation.

[0012] Preferably, the D 50 particle size of the β - lithium feldspathoid ≤ 10 μm.

[0013] Preferably, the particle size of the β - lithium feldspathoid is 0.05-5 mm and conforms to continuous gradation.

[0014] The present invention provides a preparation method of the low thermal expansion mineral casting described in the above technical solution, including the following steps:

[0015] Mix the silanized mineral aggregate, negative thermal expansion additive, and binder, and then pour the mixture into a mold, cure and form to obtain a low thermal expansion mineral casting.

[0016] Preferably, the silanized mineral aggregate is prepared according to the following steps:

[0017] Spray the solution of the silanizing reagent onto the surface of the mineral aggregate and dry to obtain the silanized mineral aggregate.

[0018] Preferably, after pouring the mixture into the mold, vibrate and compact the mold filled with the mixture.

[0019] Compared with the prior art, the present invention provides a low thermal expansion mineral casting and a preparation method thereof. The raw material components of the mineral casting provided by the present invention include: 35-70 wt% of silanized mineral aggregate, 20-60 wt% of negative thermal expansion additive, and 5-15 wt% of binder; the negative thermal expansion additive is β-eucryptite; the component of the binder is epoxy resin and curing agent. By embedding the negative thermal expansion material - β-eucryptite in the mineral casting, the present invention reduces the thermal expansion coefficient of the mineral casting, improves the manufacturing precision, and the obtained mineral casting has good isotropy, with uniform deformation in all directions, and has wide applications in machine tool manufacturing, construction or transportation. Detailed Embodiments

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] The present invention provides a low thermal expansion mineral casting, and its raw material components include: 35-70 wt% of silanized mineral aggregate, 20-60 wt% of negative thermal expansion additive, and 5-15 wt% of binder.

[0022] In the mineral casting provided by the present invention, the silanized mineral aggregate includes mineral aggregate and silanizing reagent attached to the surface of the mineral aggregate; wherein, the mineral aggregate is preferably one or more of fused quartz sand, granite and marble; the silanizing reagent is preferably one or more of γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), γ-aminopropyltriethoxysilane (KH-550), γ-methacryloxypropyltrimethoxysilane (KH-570) and γ-mercaptopropyltriethoxysilane (KH-580); the mass ratio of the mineral aggregate to the silanizing reagent in the silanized mineral aggregate is preferably 100:(1-5), and specifically can be 100:1, 100:1.5, 100:2, 100:2.5, 100:3, 100:3.5, 100:4, 100:4.5 or 100:5.

[0023] In the mineral casting provided by the present invention, the particle size of the silanized mineral aggregate is preferably 0.05-5 mm; the particle size of the silanized mineral aggregate preferably conforms to a continuous gradation, and more preferably conforms to a seven-stage continuous gradation. In the present invention, in the seven-stage continuous gradation, the particle size range of the first-stage particles is preferably 0.076-0.15 mm, and the proportion of the first-stage particles is preferably 8-12 wt%, more preferably 10.586 wt%; the particle size range of the second-stage particles is preferably 0.15-0.22 mm, and the proportion of the second-stage particles is preferably 7-11 wt%, more preferably 9.064 wt%; the particle size range of the third-stage particles is preferably 0.22-0.5 mm, and the proportion of the third-stage particles is preferably 14-18 wt%, more preferably 16.075 wt%; the particle size range of the fourth-stage particles is preferably 0.5-0.9 mm, and the proportion of the fourth-stage particles is preferably 4-8 wt%, more preferably 5.891 wt%; the particle size range of the fifth-stage particles is preferably 0.9-1.6 mm, and the proportion of the fifth-stage particles is preferably 18-22 wt%, more preferably 19.626 wt%; the particle size range of the sixth-stage particles is preferably 1.6-2.5 mm, and the proportion of the sixth-stage particles is preferably 15-19 wt%, more preferably 16.871 wt%; the particle size range of the seventh-stage particles is preferably 2.5-4 mm, and the proportion of the seventh-stage particles is preferably 19-24 wt%, more preferably 21.887 wt%.

[0024] In the mineral casting provided by the present invention, the content of the silanized mineral aggregate in the raw materials can specifically be 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt% or 70 wt%.

[0025] In the mineral casting provided by the present invention, the negative thermal expansion additive is β - lithium nepheline; the D 10 particle size of the β - lithium nepheline is preferably ≤3 μm, D 50 particle size is preferably ≤10 μm, D 90The particle size is preferably ≤20 μm; alternatively, the particle size of the β-eucryptite is preferably 0.05 - 5 mm and conforms to a continuous gradation, more preferably conforms to a seven-stage continuous gradation. In the present invention, in the seven-stage continuous gradation, the particle size range of the first-stage particles is preferably 0.076 - 0.15 mm, and the proportion of the first-stage particles is preferably 8 - 12 wt%, more preferably 10.586 wt%; the particle size range of the second-stage particles is preferably 0.15 - 0.22 mm, and the proportion of the second-stage particles is preferably 7 - 11 wt%, more preferably 9.064 wt%; the particle size range of the third-stage particles is preferably 0.22 - 0.5 mm, and the proportion of the third-stage particles is preferably 14 - 18 wt%, more preferably 16.075 wt%; the particle size range of the fourth-stage particles is preferably 0.5 - 0.9 mm, and the proportion of the fourth-stage particles is preferably 4 - 8 wt%, more preferably 5.891 wt%; the particle size range of the fifth-stage particles is preferably 0.9 - 1.6 mm, and the proportion of the fifth-stage particles is preferably 18 - 22 wt%, more preferably 19.626 wt%; the particle size range of the sixth-stage particles is preferably 1.6 - 2.5 mm, and the proportion of the sixth-stage particles is preferably 15 - 19 wt%, more preferably 16.871 wt%; the particle size range of the seventh-stage particles is preferably 2.5 - 4 mm, and the proportion of the seventh-stage particles is preferably 19 - 24 wt%, more preferably 21.887 wt%.

[0026] In the mineral casting provided by the present invention, the content of the negative thermal expansion additive in the raw materials can specifically be 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt% or 60 wt%.

[0027] In the mineral casting provided by the present invention, the binder is composed of epoxy resin and curing agent; wherein, the epoxy resin is preferably E-51 epoxy resin; the curing agent is preferably the adduct of diethylenetriamine and butyl glycidyl ether (593 curing agent); the mass ratio of the epoxy resin to the curing agent is preferably (2 - 6):1, and can specifically be 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1 or 6:1.

[0028] In the mineral casting provided by the present invention, the content of the binder in the raw materials can specifically be 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt% or 15wt%.

[0029] The present invention provides a method for preparing a low thermal expansion mineral casting as described in the above technical solution, comprising the following steps:

[0030] Mix the silanized mineral aggregate, negative thermal expansion additive and binder, and then pour the mixture into a mold and cure it to form a low thermal expansion mineral casting.

[0031] In the preparation method provided by the present invention, the specific types, key index information and dosage ratios of the silanized mineral aggregate, negative thermal expansion additive and binder have been introduced above and will not be elaborated herein.

[0032] In the preparation method provided by the present invention, the silanized mineral aggregate is prepared according to the following steps: Sprinkle a solution of a silanizing reagent on the surface of the mineral aggregate and dry it to obtain the silanized mineral aggregate. Among them, before use, the mineral aggregate is preferably dried first, the drying temperature is preferably 70-90°C, more preferably 80°C, the drying time is preferably 1-5h, more preferably 3h; the solvent in the solution is preferably ethanol and / or water, and the mass ratio of the silanizing reagent, ethanol and water in the solution is preferably 20:(60-80):(5-10), more preferably 20:72:8; the mass ratio of the mineral aggregate to the silanizing reagent in the solution is preferably 100:(1-5), and specifically can be 100:1, 100:1.5, 100:2, 100:2.5, 100:3, 100:3.5, 100:4, 100:4.5 or 100:5; the drying temperature after spraying is preferably 70-90°C, more preferably 80°C, and the drying time is preferably 2-6h, more preferably 4h.

[0033] In the preparation method provided by the present invention, before use, the negative thermal expansion additive is preferably dried first, the drying temperature is preferably 70-90°C, more preferably 80°C, and the drying time is preferably 1-5h, more preferably 3h.

[0034] In the preparation method provided by the present invention, after pouring the mixture into the mold, it is preferred to compact the mold filled with the mixture. Among them, the vibration frequency of the compaction is preferably 40-80 Hz, specifically it can be 40 Hz, 45 Hz, 50 Hz, 55 Hz, 60 Hz, 65 Hz, 70 Hz, 75 Hz or 80 Hz; the amplitude of the compaction is preferably 1-5 mm, specifically it can be 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm or 5 mm; the time of the compaction is preferably 0.5-2 h, specifically it can be 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h, 1.2 h, 1.5 h, 1.7 h or 2 h.

[0035] In the preparation method provided by the present invention, the temperature of the curing and forming is preferably 5-40 °C, specifically it can be 5 °C, 10 °C, 15 °C, 20 °C, 25 °C, 30 °C, 35 °C or 40 °C; the time of the curing and forming is preferably 12-48 h, specifically it can be 12 h, 16 h, 20 h, 24 h, 28 h, 32 h, 36 h, 40 h, 44 h or 48 h.

[0036] The technical solution provided by the present invention buries an anisotropic negative thermal expansion material - β-eucryptite in the mineral casting (microscopically, when the temperature rises, it shows an expansion behavior in the a and b axis directions of its internal unit cell, but shows a contraction in the c axis direction, and the overall expansion coefficient is -6.2×10 -6 / K; macroscopically, it shows negative expansion in a very wide temperature range (25-1000 °C)), reduces the thermal expansion coefficient of the mineral casting, improves the manufacturing accuracy, and the obtained mineral casting has good isotropy and uniform deformation in all directions. More specifically, the technical solution of the present invention has the following advantages:

[0037] (1) The density of β-eucryptite is relatively low. Low-density fillers usually have a large specific surface area, which helps to improve the interfacial bonding force between the filler and the resin. Good interfacial bonding can effectively transfer the load and improve the overall performance of the material. Moreover, low-density fillers usually show a more uniform distribution in the mineral casting, which helps to reduce the sedimentation or stratification phenomenon of the filler and optimize the macroscopic properties and consistency of the mineral casting.

[0038] (2) The raw materials of β-eucryptite are widely sourced, with low cost and good economy.

[0039] (3) The mineral aggregate is preferably fused silica sand, which has a very low coefficient of thermal expansion. Using it as the aggregate can effectively reduce the overall coefficient of thermal expansion of the mineral casting, thereby enhancing the dimensional stability of the material under temperature changes. Moreover, fused silica sand has excellent thermal stability and can maintain the stability of its physical and chemical properties under high-temperature conditions. This enables the mineral casting containing fused silica sand to maintain its performance in a high-temperature environment without a decrease in performance due to thermal expansion or material deformation. Additionally, no harmful substances are introduced during the production and use of fused silica sand, making it relatively environmentally friendly.

[0040] (4) The particle sizes of the mineral aggregate and the negative thermal expansion additive preferably conform to a continuous gradation, which helps to improve the overall density and structural strength of the material, making the mineral casting more robust when subjected to external forces or stresses. Additionally, the different particle sizes of the graded aggregate can improve the fluidity and processability of the mixture. The smaller particles can fill the voids between the larger particles, reducing the viscosity of the mixture and making it easier to form and distribute uniformly during the processing.

[0041] For the sake of clarity, the following will be described in detail through the following examples and comparative examples.

[0042] In the following examples of the present invention, the aggregate used is fused silica sand with a seven-stage continuous gradation. The gradation information is shown in the following table:

[0043]

[0044] Example 1

[0045] Prepare a mineral casting, and the specific process is as follows:

[0046] (1) Prepare 300 g of β - spodumene with a seven-stage continuous gradation (the gradation is the same as that of the seven-stage continuous gradation of fused silica sand) as the negative expansion filler, dry it at 80 °C for 3 hours to remove moisture, and cool it at room temperature.

[0047] (2) Prepare 1 kg of aggregate, dry it at 80 °C for 3 hours to remove moisture, and cool it at room temperature; mix 20 g of KH - 560 (γ-(2,3 - epoxypropoxy)propyltrimethoxysilane), 72 g of ethanol, and 8 g of deionized water, stir until clear, and then evenly spray it on the surface of the aggregate and dry it at 80 °C for 4 h to obtain the silanized aggregate.

[0048] (3) Mix epoxy resin (E - 51 epoxy resin) and 593 curing agent in a mass ratio of 4:1 to obtain the binder.

[0049] (4) Take 300 g of the above-mentioned negative expansion filler and 80 g of the above-mentioned binder, mix them evenly, and add 620 g of the above-mentioned silanized aggregate; pour the mixture into a mold, then fix it on a vibrating table, and vibrate it for 1 h under the vibration conditions of a vibration frequency of 65 Hz and an amplitude of 2.5 mm to make it dense; place the dense sample in a cool and dry place, and let it stand at room temperature for 24 h. After the sample is cured, remove the mold and cut it into appropriate mineral casting samples.

[0050] Example 2

[0051] Prepare mineral castings, and the specific process is as follows:

[0052] (1) Prepare 500 g of seven-grade continuously graded β-eucryptite (the grading information is the same as that in Example 1) as the negative expansion filler, dry it at 80 °C for 3 hours to remove moisture, and cool it at room temperature.

[0053] (2) Prepare 1 kg of aggregate, dry it at 80 °C for 3 hours to remove moisture, and cool it at room temperature; mix 20 g of KH-560 (γ-(2,3-epoxypropoxy)propyltrimethoxysilane), 72 g of ethanol and 8 g of deionized water, stir until clear, and then evenly spray it on the surface of the aggregate, and dry it at 80 °C for 4 h to obtain the silanized aggregate.

[0054] (3) Mix epoxy resin (E-51 epoxy resin) and 593 curing agent in a mass ratio of 4:1 to obtain a binder.

[0055] (4) Take 500 g of the above-mentioned negative expansion filler and 80 g of the above-mentioned binder, mix them evenly, and add 420 g of the above-mentioned silanized aggregate; pour the mixture into a mold, then fix it on a vibrating table, and vibrate it for 1 h under the vibration conditions of a vibration frequency of 65 Hz and an amplitude of 2.5 mm to make it dense; place the dense sample in a cool and dry place, and let it stand at room temperature for 24 h. After the sample is cured, remove the mold and cut it into appropriate mineral casting samples.

[0056] Example 3

[0057] Refer to Example 1, the difference is only that 300 g of ungraded β-eucryptite is used as the negative expansion filler, and the D 10 particle size of this β-eucryptite is 3 μm, D 50 particle size is 10 μm, D 90 particle size is 20 μm.

[0058] Example 4

[0059] Refer to Example 2, the difference is only that 500 g of ungraded β-eucryptite is used as the negative expansion filler, and the D 10 particle size of this β-eucryptite is 3 μm, D50 The particle size is 10 μm, D 90 The particle size is 20 μm.

[0060] Comparative Example 1

[0061] Prepare a mineral casting, and the specific process is as follows:

[0062] (1) Prepare 1 kg of aggregate, dry it at 80 °C for 3 hours to remove moisture, and cool it at room temperature; mix 20 g of KH-560 (γ-(2,3-epoxypropoxy)propyltrimethoxysilane), 72 g of ethanol and 8 g of deionized water, stir until clear, and then evenly spray it onto the surface of the aggregate, and dry it at 80 °C for 4 h to obtain the silanized aggregate.

[0063] (2) Mix epoxy resin (E-51 epoxy resin) and 593 curing agent in a mass ratio of 4:1 to obtain a binder.

[0064] (3) Take 920 g of the above-mentioned silanized aggregate and 80 g of the above-mentioned binder, mix them evenly; pour the mixture into a mold, then fix it on a vibrating table, and vibrate it for 1 h under the vibration conditions of a vibration frequency of 65 Hz and an amplitude of 2.5 mm to make it dense; place the dense sample in a cool and dry place, and let it stand at room temperature for 24 h. After the sample is cured, remove the mold and cut it into appropriate mineral casting samples.

[0065] Performance test

[0066] Perform performance tests on the mineral castings prepared in Examples 1 to 4 and Comparative Example 1, and the results are shown in the following table:

[0067]

[0068] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A low thermal expansion mineral casting, characterized in that: The raw material components include: 35-70wt% of silanized mineral aggregate, 20-60wt% of negative thermal expansion additive and 5-15wt% of binder; the silanized mineral aggregate includes mineral aggregate and a silanization agent attached to the surface of the mineral aggregate, the mineral aggregate is fused quartz sand, the particle size of the silanized mineral aggregate is 0.05-5mm and meets the continuous grading; the negative thermal expansion additive is β-eucryptite, and the D 50 The particle size is ≤10 μm, or the particle size of the β-eucryptite is 0.05-5 mm and conforms to continuous grading; the components of the binder are epoxy resin and curing agent.

2. The low thermal expansion mineral casting according to claim 1, characterized in that: The silanization agent is one or more of γ-(2,3-epoxypropyloxy)propyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane and γ-mercaptopropyltriethoxysilane.

3. The low thermal expansion mineral casting according to claim 2, characterized in that: The mass ratio of the mineral aggregate to the silanization agent in the silanized mineral aggregate is 100:(1-5).

4. A method for preparing a low thermal expansion mineral casting according to any one of claims 1 to 3, characterized in that: The following steps are involved: The silanized mineral aggregate, the negative thermal expansion additive and the binder are mixed, and then the mixture is poured into a mold and solidified to obtain a low thermal expansion mineral casting.

5. The preparation method according to claim 4, characterized in that: The silanized mineral aggregate is prepared according to the following steps: The silanization agent solution is sprayed onto the surface of the mineral aggregate and dried to obtain the silanized mineral aggregate.

6. The preparation method according to claim 4, characterized in that: After the mixture is poured into the mold, the mold containing the mixture is vibrated.

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