Alkali-resistant basalt fiber as well as preparation method and application thereof

Abstract

The invention relates to the technical field of basalt fibers, and discloses an alkali-resistant basalt fiber and a preparation method and application thereof.The alkali-resistant basalt fiber is prepared from, by mass, 40%-70% of SiO2, 4%-11% of Al2O3, 2%-8% of CaO + MgO, 2%-9% of Fe2O3 + FeO, 4%-13% of K2O + Na2O, 4%-10% of TiO2, 2%-9% of ZrO2, 1%-6% of B2O3, 1%-6% of MoO2 and 1%-4% of Ta2O5 + Nb2O5; the basalt fiber disclosed by the invention can keep relatively high stability under an alkaline condition, and the service life of the basalt fiber is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of basalt fiber, and particularly relates to an alkali-resistant basalt fiber, a preparation method thereof, and an application thereof. Background Art

[0002] Basalt fiber has low cost, high cost performance, energy conservation, environmental protection, non-toxic and harmless in the production process, and is known as the "green material and new material" without pollution in the 21st century. Compared with glass fiber, basalt fiber has excellent properties such as high mechanical properties (high elastic modulus, high fracture strength), good insulation performance, excellent heat resistance and thermal stability, and strong radiation resistance, making it widely used in the fields of national defense and military industry, transportation, construction, vehicle and ship manufacturing, petrochemical industry, environmental protection equipment, electronic information, aerospace, etc. However, due to the use of natural basalt ore as raw material, the properties of the prepared basalt fiber are relatively single. Under alkaline conditions, Si element, Al element, and B element in the fiber material react with OH - to cause fiber damage and reduce the physical and chemical properties of the fiber. Therefore, how to effectively improve the alkali resistance of basalt fiber is one of the key problems urgently needed to be solved in this field.

[0003] For this reason, related technologies have disclosed a method, product, and equipment for manufacturing alkali-resistant basalt fiber. Although this method discloses that after soaking in a saturated Ca(OH)2 solution at 100°C for 4 hours, the tensile strength of the fiber can still remain above 800 MPa, and the retention rate of the single-filament strength exceeds 75%; however, the total content of SiO2 and Al2O3 is relatively high, resulting in unsatisfactory alkali resistance; and the raw materials include fluorite, which decomposes to generate fluorine-containing gases during the production process of the fiber, not only polluting the air but also possibly having an adverse impact on the growth environment of surrounding organisms; related technologies have disclosed a formula for alkali-resistant basalt fiber with a multi-mineral combination. The formula is 40-60 parts by weight of basalt, 5-15 parts by weight of dolomite, 10-18 parts by weight of white bubble stone, 6-8 parts by weight of zircon, 2-5 parts by weight of ilmenite, 5-10 parts by weight of celestite, 6-14 parts by weight of calcite, 3-9 parts by weight of diopside, and 8-11 parts by weight of kaolin. The finished product is soaked in an alkaline solution for 28 days. However, the calculated loss rate of SiO2 in the fiber is relatively high.

[0004] Therefore, how to optimize and improve basalt fiber to improve its alkali resistance is one of the technical problems urgently needed to be solved in this field. Summary of the Invention

[0005] In view of this, the present invention provides an alkali-resistant basalt fiber.

[0006] The present invention also provides a preparation method of the above alkali-resistant basalt fiber.

[0007] In a first aspect, the present invention provides an alkali-resistant basalt fiber. In terms of mass percentage content, the chemical composition of the basalt fiber includes: SiO2 40%-70%, Al2O3 4%-11%, CaO+MgO 2%-8%, Fe2O3+FeO 2%-9%, K2O+Na2O 4%-13%, TiO2 4%-10%, ZrO2 2%-9%, B2O3 1%-6%, MoO2 1%-6%, Ta2O5+Nb2O5 1%-4%.

[0008] In an alternative embodiment, the chemical composition of the basalt fiber includes: SiO2 45%-69%, Al2O3 5%-10%, CaO+MgO 4%-6%, Fe2O3+FeO 3%-6%, K2O+Na2O 5%-9%, TiO2 6%-7%, ZrO2 4%-6%, B2O3 2%-4%, MoO2 1%-4%, Ta2O5+Nb2O5 1%-3%.

[0009] In an alternative embodiment, the chemical composition of the basalt fiber includes: SiO2 54%, Al2O3 10%, CaO+MgO 5%, Fe2O3+FeO 6%, K2O+Na2O 7%, TiO2 7%, ZrO2 5%, B2O3 3%, MoO2 2%, Ta2O5+Nb2O5 1%.

[0010] In an alternative embodiment, the chemical composition of the basalt fiber includes: SiO2 56%, Al2O3 9%, CaO+MgO 4%, Fe2O3+FeO 4%, K2O+Na2O 6%, TiO2 6%, ZrO2 6%, B2O3 4%, MoO2 3%, Ta2O5+Nb2O5 2%.

[0011] In an alternative embodiment, the chemical composition of the basalt fiber includes: SiO2 59%, Al2O3 5%, CaO+MgO 6%, Fe2O3+FeO 3%, K2O+Na2O 8%, TiO2 6%, ZrO2 4%, B2O3 2%, MoO2 4%, Ta2O5+Nb2O5 3%.

[0012] In a second aspect, the present invention provides a method for preparing the above alkali-resistant basalt fiber, comprising the following steps: (1) Mixing and stirring the raw materials of the alkali-resistant basalt fiber to obtain a mixed material; (2) Subjecting the mixed material to melting and wire drawing treatments in sequence to obtain the alkali-resistant basalt fiber; The raw material composition of the alkali-resistant basalt fiber includes basalt, rutile, zircon, ascharite, potassium feldspar, molybdenite, and tantalum-niobium ore tailings.

[0013] In an alternative embodiment, the melting temperature is 1450°C - 1600°C.

[0014] In an alternative embodiment, the drawing temperature is 1320°C - 1450°C.

[0015] In an alternative embodiment, in step (1), before the mixing and stirring, grinding and magnetic separation treatments are further included in sequence.

[0016] In an alternative embodiment, the mass ratio of the basalt, the rutile, the zircon, the ascharite, the potassium feldspar, the molybdenite, and the tantalum-niobium ore tailings is 60 - 100:5 - 13:5 - 15:3 - 10:3 - 40:2 - 8:20 - 50.

[0017] In a third aspect, the present invention provides the application of the above alkali-resistant basalt fiber in civil engineering and aerospace.

[0018] Compared with the prior art, the technical solution of the present invention has the following advantages: 1. The alkali-resistant basalt fiber provided by the present invention, the chemical composition of the basalt fiber includes: SiO2 40%-70%, Al2O3 4%-11%, CaO+MgO 2%-8%, Fe2O3+FeO 2%-9%, K2O+Na2O 4%-13%, TiO2 4%-10%, ZrO2 2%-9%, B2O3 1%-6%, MoO2 1%-6%, Ta2O5+Nb2O5 1%-4%; the basalt fiber of the present invention can maintain high stability under alkaline conditions and extend its service life. Specifically: The main component of potassium feldspar is potassium aluminosilicate, which is a common feldspar mineral, mainly providing potassium element and silicate components. Potassium feldspar has a low melting point and a long melting time, which can improve the melting performance of the basalt fiber raw material and make it easier to draw into fiber filaments; MgO, Na2O, and CaO can fill and supplement the network structure inside the basalt fiber, which is beneficial to improving the alkali-resistant corrosion of the fiber; the main component of rutile is TiO2, which can improve the corrosion resistance and waterproof performance of the basalt fiber; ZrO2 can improve the alkali-resistant corrosion of the basalt fiber and also improve the heat resistance of the basalt fiber; the main components of ascharite include elements such as magnesium and boron, which is a common boron mineral. Using ascharite to provide boron element, the addition of boron element can improve the chemical stability of the basalt fiber and make it show good corrosion resistance in different chemical environments; molybdenite contains rich molybdenum element, and molybdenum element has excellent corrosion resistance. Adding it to the basalt fiber is beneficial to enhancing the corrosion resistance of the basalt fiber under alkaline conditions; tantalum-niobium ore tailings contain rich tantalum element and niobium element. Tantalum element and niobium element have strong corrosion resistance and high melting points. Adding them to the basalt fiber is beneficial to enhancing the adaptability of the basalt fiber to the corrosion environment and extending the service life of the fiber; at the same time, it is beneficial to improve the heat resistance and mechanical properties (tensile strength, elastic modulus) of the basalt fiber, so that it can maintain excellent performance in extreme high-temperature environments.

[0019] The alkali-resistant basalt fiber provided by the present invention has a lower cost and a longer service life compared with ordinary basalt fiber materials, and is suitable for use under extreme conditions.

[0020] 2. The preparation method of the alkali-resistant basalt fiber of the present invention has a simple raw material composition, a mature preparation process, and is easy to realize industrial production and popularization and application.

[0021] 3. The preparation method of the alkali-resistant basalt fiber of the present invention further includes grinding and magnetic separation treatment before the stirring and mixing step, which can effectively remove impurities in the raw materials. Specific Embodiments

[0022] The following embodiments are provided to better further understand the present invention, which is not limited to the described optimal embodiment, and does not limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with those of other prior arts falls within the protection scope of the present invention.

[0023] For those embodiments where specific experimental steps or conditions are not indicated, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For the reagents or instruments whose manufacturers are not indicated, they are all conventional reagent products that can be obtained through commercial purchase.

[0024] The present invention will be further described in detail below in conjunction with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present invention.

[0025] Example 1 This embodiment provides a preparation method for alkali-resistant basalt fibers, which includes the following steps: (1) Weigh 79 parts by weight of basalt, 7 parts by weight of rutile, 10 parts by weight of zircon, 3 parts by weight of ascharite, 3 parts by weight of potassium feldspar, 3 parts by weight of molybdenite, and 20 parts by weight of tantalum-niobium ore tailings. After fine grinding, magnetic separation treatment, and stirring and mixing, a mixed material is obtained; (2) Melting the above mixed material in a high-temperature furnace at 1500 °C to obtain a basalt fiber melt; (3) Drawing and pulling the above basalt fiber melt through a platinum-rhodium alloy spinneret at 1320 °C; wherein, the composition of the basalt fiber includes: SiO2 54%, Al2O3 10%, CaO + MgO 5%, Fe2O3 + FeO 6%, K2O + Na2O 7%, TiO2 7%, ZrO2 5%, B2O3 3%, MoO2 2%, Ta2O5 + Nb2O5 1%; and then through a buncher, a fiber tensioner, and an automatic winding machine under the action of a sizing agent to finally form a bobbin.

[0026] Example 2 This embodiment provides a preparation method for alkali-resistant basalt fibers, which includes the following steps: (1) Weigh 82 parts by weight of basalt, 6 parts by weight of rutile, 8 parts by weight of zircon, 9 parts by weight of ascharite, 9 parts by weight of potassium feldspar, 4 parts by weight of molybdenite, and 40 parts by weight of tantalum-niobium ore tailings. After fine grinding, magnetic separation treatment, and stirring and mixing, a mixed material is obtained; (2) Melting the above mixed material in a high-temperature furnace at 1550 °C to obtain a basalt fiber melt; (3) It is obtained by drawing and pulling the above basalt fiber melt with a platinum-rhodium alloy spinneret at 1380°C; among them, the composition of the basalt fiber includes: 56% SiO2, 9% Al2O3, 4% CaO + MgO, 4% Fe2O3 + FeO, 6% K2O + Na2O, 6% TiO2, 6% ZrO2, 4% B2O3, 3% MoO2, 2% Ta2O5 + Nb2O5; and then it is formed into a cylinder through a buncher, a fiber tensioner, and an automatic winding machine under the action of a sizing agent.

[0027] Example 3 This example provides a method for preparing alkali-resistant basalt fiber, which includes the following steps: (2) Weigh 84 parts by weight of basalt, 9 parts by weight of rutile, 8 parts by weight of zircon, 5 parts by weight of ascharite, 30 parts by weight of potassium feldspar, 8 parts by weight of molybdenite, and 30 parts by weight of tantalum-niobium ore tailings. After fine grinding, magnetic separation treatment, and stirring and mixing, a mixed material is obtained; (2) Melting the above mixed material in a high-temperature furnace at 1600°C to obtain a basalt fiber melt; (3) It is obtained by drawing and pulling the above basalt fiber melt with a platinum-rhodium alloy spinneret at 1450°C; among them, the composition of the basalt fiber includes: 59% SiO2, 5% Al2O3, 6% CaO + MgO, 3% Fe2O3 + FeO, 8% K2O + Na2O, 6% TiO2, 4% ZrO2, 2% B2O3, 4% MoO2, 3% Ta2O5 + Nb2O5; and then it is formed into a cylinder through a buncher, a fiber tensioner, and an automatic winding machine under the action of a sizing agent.

[0028] Example 4 This example provides a method for preparing alkali-resistant basalt fiber, which includes the following steps: (1) Weigh 89 parts by weight of basalt, 7 parts by weight of rutile, 10 parts by weight of zircon, 3 parts by weight of ascharite, 40 parts by weight of potassium feldspar, 5 parts by weight of molybdenite, and 50 parts by weight of tantalum-niobium ore tailings. After fine grinding, magnetic separation treatment, and stirring and mixing, a mixed material is obtained; (2) Melting the above mixed material in a high-temperature furnace at 1450°C to obtain a basalt fiber melt; (3) It is obtained by drawing and pulling the above-mentioned basalt fiber melt through a platinum-rhodium alloy spinneret at 1350 °C; among them, the composition of the basalt fiber includes: 60% SiO2, 11% Al2O3, 2% CaO + MgO, 2% Fe2O3 + FeO, 9% K2O + Na2O, 4% TiO2, 2% ZrO2, 1% B2O3, 5% MoO2, 4% Ta2O5 + Nb2O5; and then through a buncher, a fiber tensioner, and an automatic winding machine under the action of a sizing agent to finally form a bobbin.

[0029] Example 5 This example provides a method for preparing alkali-resistant basalt fiber, which includes the following steps: (1) Weigh 65 parts by weight of basalt, 5 parts by weight of rutile, 15 parts by weight of zircon, 10 parts by weight of ascharite, 20 parts by weight of potassium feldspar, 2 parts by weight of molybdenite, and 50 parts by weight of tantalum-niobium ore tailings, and obtain a mixed material after fine grinding, magnetic separation treatment, and stirring and mixing; (2) Melt the above-mentioned mixed material in a high-temperature furnace at 1600 °C to obtain a basalt fiber melt; (3) It is obtained by drawing and pulling the above-mentioned basalt fiber melt through a platinum-rhodium alloy spinneret at 1450 °C; among them, the composition of the basalt fiber includes: 47% SiO2, 4% Al2O3, 7% CaO + MgO, 2% Fe2O3 + FeO, 13% K2O + Na2O, 5% TiO2, 7% ZrO2, 5% B2O3, 6% MoO2, 4% Ta2O5 + Nb2O5; and then through a buncher, a fiber tensioner, and an automatic winding machine under the action of a sizing agent to finally form a bobbin.

[0030] Example 6 This example provides a method for preparing alkali-resistant basalt fiber, which includes the following steps: (1) Weigh 60 parts by weight of basalt, 10 parts by weight of rutile, 5 parts by weight of zircon, 3 parts by weight of ascharite, 17 parts by weight of potassium feldspar, 6 parts by weight of molybdenite, and 50 parts by weight of tantalum-niobium ore tailings, and obtain a mixed material after fine grinding, magnetic separation treatment, and stirring and mixing; (2) Melt the above-mentioned mixed material in a high-temperature furnace at 1580 °C to obtain a basalt fiber melt; (3) It is obtained by drawing and pulling the above-mentioned basalt fiber melt through a platinum-rhodium alloy spinneret at 1425°C; among them, the composition of the basalt fiber includes: 41% SiO2, 11% Al2O3, 8% CaO + MgO, 8% Fe2O3 + FeO, 10% K2O + Na2O, 10% TiO2, 2% ZrO2, 1% B2O3, 5% MoO2, 4% Ta2O5 + Nb2O5; and then it is formed into a bobbin through a buncher, a fiber tensioner, and an automatic winding machine under the action of a sizing agent.

[0031] Comparative Example 1 This comparative example provides a method for preparing alkali-resistant basalt fiber, which is basically the same as the steps of Example 1, except that the raw material composition includes: 80 parts by weight of basalt, 10 parts by weight of rutile, 10 parts by weight of zircon, 3 parts by weight of ascharite, 6 parts by weight of potassium feldspar, 4 parts by weight of molybdenite, 41 parts by weight of tantalum-niobium ore tailings, and the composition of the basalt fiber includes: 55% SiO2, 8% Al2O3, 3% CaO + MgO, 5% Fe2O3 + FeO, 4% K2O + Na2O, 10% TiO2, 5% ZrO2, 1% B2O3, 4% MoO2, 5% Ta2O5 + Nb2O5.

[0032] Comparative Example 2 This comparative example provides a method for preparing alkali-resistant basalt fiber, which is basically the same as the steps of Example 1, except that the raw material composition includes: 83 parts by weight of basalt, 6 parts by weight of rutile, 7 parts by weight of zircon, 9 parts by weight of ascharite, 28 parts by weight of potassium feldspar, 2 parts by weight of molybdenite, 18 parts by weight of tantalum-niobium ore tailings, and the composition of the basalt fiber includes: 57% SiO2, 10% Al2O3, 8% CaO + MgO, 2% Fe2O3 + FeO, 10% K2O + Na2O, 4% TiO2, 3% ZrO2, 3% B2O3, 2.5% MoO2, 0.5% Ta2O5 + Nb2O5.

[0033] Comparative Example 3 This comparative example provides a method for preparing alkali-resistant basalt fiber, which is basically the same as the steps of Example 1, except that it includes: 80 parts by weight of basalt, 10 parts by weight of rutile, 9 parts by weight of zircon, 4 parts by weight of ascharite, 5 parts by weight of potassium feldspar, 11 parts by weight of molybdenite, 22 parts by weight of tantalum-niobium ore tailings, and the composition of the basalt fiber includes: 55% SiO2, 5% Al2O3, 2% CaO + MgO, 3% Fe2O3 + FeO, 4% K2O + Na2O, 9% TiO2, 8% ZrO2, 6% B2O3, 7% MoO2, 1% Ta2O5 + Nb2O5.

[0034] Comparative Example 4 This comparative example provides a method for preparing alkali-resistant basalt fibers, which is basically the same as the steps of Example 1, except that the raw material composition includes: 86 parts by weight of basalt, 9 parts by weight of rutile, 9 parts by weight of zircon, 4 parts by weight of ascharite, 4 parts by weight of potassium feldspar, 1 part by weight of molybdenite, and 28 parts by weight of tantalum-niobium ore tailings. The composition of the basalt fiber includes: 59% SiO2, 5% Al2O3, 2% CaO + MgO, 2% Fe2O3 + FeO, 4% K2O + Na2O, 9% TiO2, 9% ZrO2, 6% B2O3, 0.5% MoO2, and 3.5% Ta2O5 + Nb2O5.

[0035] Experimental Example 1 Cut the basalt fibers prepared in each example and comparative example into samples with uniform sizes, and evenly divide them into four groups. Place them in 0.1 mol / L NaOH solution and 1 mol / L NaOH solution respectively. After standing for 12 h, 24 h, and 36 h, calculate the loss rate of each sample respectively.

[0036] Under alkaline environmental conditions, the following reactions occur on the surface of the basalt fiber samples:

[0037] According to the following formula, calculate the loss rate of the basalt fiber in NaOH solutions with different concentrations. The results are shown in Table 1:

[0038] Among them, m1 is the mass of the basalt fiber before corrosion, and m2 is the mass of the basalt fiber after corrosion.

[0039] Table 1 Loss rates of basalt fibers in each example and comparative example in NaOH solutions with different concentrations (%)

[0040] As can be seen from the above table, the loss rates of the basalt fibers prepared in Examples 1 - 6 are 3.04% - 5.23% at 12 h, 3.33% - 5.58% at 24 h, and 3.76% - 5.83% at 36 h; in the basalt fiber prepared in Comparative Example 1, the content of Ta2O5 + Nb2O5 is too large, which destroys the silicon - oxygen tetrahedron structure in the basalt fiber, causes the fracture of the silicate network, and reduces its alkali - resistance; in the basalt fiber prepared in Comparative Example 2, the content of Ta2O5 + Nb2O5 is too small to significantly change the alkali - resistance of the basalt fiber; in the basalt fiber prepared in Comparative Example 3, the content of MoO2 is too large, which destroys the network structure of the basalt fiber, accelerates the erosion in the alkaline solution, and leads to an increase in the mass loss of the basalt fiber; in the basalt fiber prepared in Comparative Example 4, the content of MoO2 is relatively small and fails to significantly change the properties of the basalt fiber. Due to its poor alkali - resistance, it has a large mass loss rate in the alkaline solution.

[0041] Obviously, the above - mentioned examples are only for clear illustration and not for limiting the implementation manners. For those of ordinary skill in the art, based on the above description, other different forms of changes or modifications can be made. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. An alkali-resistant basalt fiber, characterized in that, In terms of mass percentage, the chemical composition of the basalt fiber includes: SiO2 40% - 70%, Al2O3 4% - 11%, CaO + MgO 2% - 8%, Fe2O3 + FeO 2% - 9%, K2O + Na2O 4% - 13%, TiO2 4% - 10%, ZrO2 2% - 9%, B2O3 1% - 6%, MoO2 1% - 6%, Ta2O5 + Nb2O5 1% - 4%.

2. The alkali-resistant basalt fiber according to claim 1, characterized in that, The chemical composition of the basalt fiber includes: SiO2 45% - 69%, Al2O3 5% - 10%, CaO + MgO 4% - 6%, Fe2O3 + FeO 3% - 6%, K2O + Na2O 5% - 9%, TiO2 6% - 7%, ZrO2 4% - 6%, B2O3 2% - 4%, MoO2 1% - 4%, Ta2O5 + Nb2O5 1% - 3%.

3. The alkali-resistant basalt fiber according to claim 1 or 2, characterized in that, The chemical composition of the basalt fiber includes: SiO2 54%, Al2O3 10%, CaO + MgO 5%, Fe2O3 + FeO 6%, K2O + Na2O 7%, TiO2 7%, ZrO2 5%, B2O3 3%, MoO2 2%, Ta2O5 + Nb2O5 1%.

4. The alkali-resistant basalt fiber according to claim 1 or 2, characterized in that, The chemical composition of the basalt fiber includes: SiO2 56%, Al2O3 9%, CaO + MgO 4%, Fe2O3 + FeO 4%, K2O + Na2O 6%, TiO2 6%, ZrO2 6%, B2O3 4%, MoO2 3%, Ta2O5 + Nb2O5 2%.

5. The alkali-resistant basalt fiber according to claim 1 or 2, characterized in that, The chemical composition of the basalt fiber includes: SiO2 59%, Al2O3 5%, CaO + MgO 6%, Fe2O3 + FeO 3%, K2O + Na2O 8%, TiO2 6%, ZrO2 4%, B2O3 2%, MoO2 4%, Ta2O5 + Nb2O5 3%.

6. A method for preparing an alkali-resistant basalt fiber according to any one of claims 1-5, characterized in that, It includes the following steps: (1) Mix and stir the raw materials of the alkali-resistant basalt fiber to obtain a mixed material; (2) The mixed material is successively subjected to melting and wire drawing treatments to obtain the alkali-resistant basalt fiber; The raw material composition of the alkali-resistant basalt fiber includes basalt, rutile, zircon, ascharite, potassium feldspar, molybdenite, and tantalum-niobium ore tailings.

7. The preparation method of the alkali-resistant basalt fiber according to claim 6, wherein, The melting temperature is 1450°C - 1600°C; And / or, the wire drawing temperature is 1320°C - 1450°C.

8. The preparation method of the alkali-resistant basalt fiber according to claim 6 or 7, characterized in that, In step (1), before the mixing and stirring, it also includes successively performing grinding and magnetic separation treatments.

9. The method for preparing alkali-resistant basalt fibers according to claim 6 or 7, characterized in that, The mass ratio of the basalt, the rutile, the zircon, the ascharite, the potassium feldspar, the molybdenite, and the tantalum-niobium ore tailings is 60 - 100:5 - 13:5 - 15:3 - 10:3 - 40:2 - 8:20 - 50.

10. Use of the alkali-resistant basalt fiber according to any one of claims 1-5 or the alkali-resistant basalt fiber prepared by the preparation method according to any one of claims 6-9 in civil engineering and aerospace.

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