阅读说明：本技术 一种无机纤维复合硅基陶瓷型芯及其制备方法 (Inorganic fiber composite silicon-based ceramic core and preparation method thereof ) 是由 李飞 于 2019-10-22 设计创作，主要内容包括：本发明属于陶瓷制备技术领域,涉及一种基于3D打印技术的无机纤维复合硅基陶瓷型芯,其型芯料浆由石英玻璃粉、矿化剂、陶瓷纤维和光固化树脂组成。本发明的陶瓷型芯制备步骤是：将85~95wt%的石英玻璃粉、3~10wt%的硅酸锆粉、2~5wt%的氧化铝纤维搅拌干混后,加占比30~50wt%光固化树脂球磨共混,获得陶瓷型芯料浆；3D打印出陶瓷型芯素坯,再浸泡去除多余的未固化树脂；陶瓷型芯素坯放入紫外固化箱二次固化；陶瓷型芯素坯置于陶瓷匣钵的轻质氧化镁粉中,在型芯烧结炉中烧结；型芯吹粉清理并检测后修型；最后型芯强化,获得无机纤维复合硅基陶瓷型芯。本发明提供的硅基陶瓷型芯及制备方法,可制备结构复杂、具有优良抗高温蠕变和脱芯性能的硅基陶瓷型芯。(The invention belongs to the technical field of ceramic preparation, and relates to an inorganic fiber composite silicon-based ceramic core based on a 3D printing technology, wherein core slurry of the inorganic fiber composite silicon-based ceramic core comprises quartz glass powder, a mineralizer, ceramic fibers and light-cured resin.)

1. An inorganic fiber composite silicon-based ceramic core is characterized in that: carrying out photocuring 3D printing on the core slurry, sintering, and reinforcing with ethyl silicate hydrolysate to obtain the silicon-based ceramic core, wherein the core slurry is composed of quartz glass powder, a mineralizer, ceramic fibers and photocuring resin.

2. The inorganic fiber composite silicon-based ceramic core of claim 1, wherein: SiO in the quartz glass powder₂The content is more than 99wt%, and the particle size distribution is 1-30 μm.

3. The inorganic fiber composite silicon-based ceramic core of claim 1, wherein: the mineralizer is zirconium silicate micro powder, wherein Fe₂O₃The impurity content is less than 0.1wt%, and the particle size distribution is 1-30 μm.

4. The inorganic fiber composite silicon-based ceramic core of claim 1, wherein: the ceramic fiber is alumina fiber with alpha-alumina content over 99wt%, diameter of 5-10 micron and length of 50-300 micron.

5. The inorganic fiber composite silicon-based ceramic core of claim 1, wherein: the photocuring resin is water-based polyurethane acrylate or water-based epoxy acrylate or polyester acrylate containing a photoinitiator, and the viscosity is less than or equal to 270CPS at the temperature of 30 ℃.

6. The inorganic fiber composite silicon-based ceramic core of claim 1, wherein: the ethyl silicate hydrolysate is prepared by mixing the following components: 34.3% of ethyl silicate, 25% of absolute ethyl alcohol, 1.5% of isopropanol, 13% of propylene glycol methyl ether, 25.8% of acidic silica sol and 0.4% of hydrochloric acid with the mass concentration of 20%, wherein the components are in mass percentage.

7. The method of making an inorganic fiber composite silicon-based ceramic core according to any of claims 1-6, comprising the steps of:

preparing core slurry: adding 85-95wt% of quartz glass powder, 3-10wt% of zirconium silicate powder and 2-5wt% of alumina fiber into a mixer, and forcibly stirring and dry-mixing for 2-5h to obtain a ceramic core material; adding light-cured resin accounting for 30-50wt% of the ceramic core material into a planetary ball mill, adding the ceramic core material according to the proportion, and performing ball milling and blending for 30-60min to obtain ceramic core slurry;

3D printing of core biscuit: establishing a 3D model of the ceramic core by a computer, decomposing the 3D model into a series of two-dimensional models with the thickness of 100-;

secondary curing of the core biscuit: putting the core biscuit obtained in the step 2) into an ultraviolet curing box to be cured for 1-5 hours continuously;

and (3) core sintering: placing the core biscuit obtained in the step 3) into light magnesium oxide powder of a ceramic sagger, and sintering in a core sintering furnace, wherein the sintering temperature is as follows: heating to 200 ℃ and preserving heat for 2h, heating to 500 ℃ and preserving heat for 2h, heating to 1000 ℃ and preserving heat for 2h, then heating to 1200 ℃ and preserving heat for 2h, wherein the heating speed is 30 ℃/h, cooling to room temperature along with the furnace, and then discharging;

and (3) core trimming: carrying out surface powder blowing cleaning on the sintered ceramic core, and then detecting and modifying the shape by using a core measuring tool;

core strengthening: and putting the core into a container filled with ethyl silicate hydrolysate, then putting the container in a negative pressure environment to enable the ethyl silicate hydrolysate to permeate into pores of the core, keeping the soaking time for 2 hours, then putting the core on a frame to be dried for 24 hours, and finally drying the core for 2 hours at 150 ℃ to obtain the inorganic fiber composite silicon-based ceramic core.

Technical Field

The invention relates to the technical field of ceramic preparation, in particular to an inorganic fiber composite silicon-based ceramic core and a preparation method thereof.

Background

With the increasing of the temperature of the gas before the turbine of the aviation gas turbine engine, the improvement of the heat dissipation capacity of the turbine blade through the complex air-cooling inner cavity structure becomes the key of the advanced engine manufacturing, and therefore higher requirements are put forward on the ceramic core for forming the inner cavity structure of the blade. Ceramic cores are key components in the manufacture of high performance turbine blades, and their performance and quality directly affect the performance of the turbine blades.

The traditional method for forming the ceramic core mainly comprises hot-pressing injection molding, wherein a base material and a mineralizer are uniformly mixed, a plasticizer is added at the same time, then ceramic biscuit is obtained after hot-pressing injection molding, and the biscuit is sintered to obtain the ceramic core. The hot-pressing injection molding is beneficial to casting ceramic cores with complex structures and fine sizes, but the slurry needs to be heated and provided with pressure during pouring, the wax removal time is long, and the process is complex.

The silica-based ceramic core using quartz glass as a main raw material is most widely applied to the manufacture of high-temperature alloy columnar crystals and single crystal blades due to the excellent decoring performance. However, because the silicon-based core has a low fire resistance temperature, the silicon-based core is generally applied below 1560 ℃, and meanwhile, the silicon-based core has low high-temperature strength and poor high-temperature creep resistance, and the application of the silicon-based core is limited to a certain extent. Therefore, if the high-temperature strength and the high-temperature creep resistance can be improved, the alloy is expected to be applied to the precision casting and forming of large-scale high-temperature alloy hollow blades such as gas turbine orientation and single crystal blades. Patent 201410224963.X discloses a fiber-reinforced ceramic core material and a hot-press injection molding process, which show that the addition of silicon carbide fiber can avoid the cracking of the core in the roasting process, however, the early preparation process of the core material is relatively complex, and the cost of the silicon carbide fiber is high, so that the practical application of the core material is limited.

The 3D printing method is different from the traditional material reducing (such as cutting) and material waiting (such as forging) manufacturing methods, a mold is not needed in the manufacturing process, a complex structure which cannot be achieved or is difficult to achieve by the traditional method can be realized, the processing procedures are greatly reduced, the processing period is shortened, and the technical characteristics well accord with the manufacturing requirements of the ceramic core. At present, the 3DP process in the 3D printing technology is successfully used for manufacturing sand cores in the field of sand casting, and is widely applied to forming of complex aluminum alloy castings. However, the ceramic product printed by the 3DP process has high surface roughness, and generally cannot meet the requirement of precision casting of the oriented blade with high surface precision. Patent 201710284229.6 discloses a method for making a short fiber mixed calcium oxide based ceramic powder and uses a 3DP process to achieve integral formation of a ceramic core and shell, however, the patent does not disclose surface roughness data of the ceramic core.

Disclosure of Invention

The invention aims to solve the defects of the technology and provide an inorganic fiber composite silicon-based ceramic core based on a 3D printing technology and a preparation method thereof, and the inorganic fiber composite silicon-based ceramic core can be used for preparing a silicon-based ceramic core with a complex structure and excellent high-temperature creep resistance and decoring performance.

In order to achieve the purpose, the invention provides the following technical scheme:

the invention provides an inorganic fiber composite silicon-based ceramic core, which is prepared by carrying out photocuring 3D printing on core slurry, sintering and reinforcing by ethyl silicate hydrolysate to obtain the silicon-based ceramic core, wherein the core slurry is composed of quartz glass powder, a mineralizer, ceramic fibers and photocuring resin.

Preferably, SiO in the silica glass frit₂The content is more than 99wt%, and the particle size distribution is 1-30 μm.

Preferably, the mineralizer is zirconium silicate micro powder, wherein Fe₂O₃The impurity content is less than 0.1wt%, and the particle size distribution is 1-30 μm.

Preferably, the ceramic fibers are preferably alumina fibers having an alpha-alumina content > 99wt%, a diameter of 5-10 μm and a length of 50-300 μm.

Preferably, the light-cured resin is water-based polyurethane acrylate or water-based epoxy acrylate or polyester acrylate containing a photoinitiator, the viscosity is less than or equal to 270CPS (30 ℃), and the light-cured resin can be cured under the irradiation of ultraviolet light to combine the ceramic powder and the fiber material together.

The source of the photocurable resin in the present invention is not particularly limited, and commercially available products familiar to those skilled in the art may be used.

The preferable components and mass percentage content of the ethyl silicate hydrolysate are as follows: 34.3 percent of ethyl silicate, 25 percent of absolute ethyl alcohol, 1.5 percent of isopropanol, 13 percent of propylene glycol methyl ether, 25.8 percent of acidic silica sol and 0.4 percent of hydrochloric acid (20 percent of mass concentration) which are mixed by a stirrer. In the present invention, the sources of the components of the silicate hydrolysis solution are not particularly limited, and commercially available products known to those skilled in the art may be used.

The invention provides a preparation method of an inorganic fiber composite silicon-based ceramic core, which comprises the following steps:

1) preparing core slurry: adding 85-95wt% of quartz glass powder, 3-10wt% of zirconium silicate powder and 2-5wt% of alumina fiber into a V-shaped mixer, and forcibly stirring and dry-mixing for 2-5h to obtain a ceramic core material; adding light-cured resin accounting for 30-50wt% of the ceramic core material into a planetary ball mill, adding the ceramic core material according to the proportion, and performing ball milling and blending for 30-60min to obtain ceramic core slurry;

2) 3D printing of core biscuit: establishing a 3D model of the ceramic core by a computer, decomposing the 3D model into a series of two-dimensional models with the thickness of 100-;

3) secondary curing of the core biscuit: putting the ceramic core biscuit obtained in the step 2) into an ultraviolet curing box to be cured for 1-5 hours continuously;

4) and (3) core sintering: placing the ceramic core biscuit obtained in the step 3) into light magnesium oxide powder of a ceramic sagger, and sintering in a core sintering furnace, wherein the optimized sintering temperature is as follows: heating to 200 ℃ and preserving heat for 2h, heating to 500 ℃ and preserving heat for 2h, heating to 1000 ℃ and preserving heat for 2h, then heating to 1200 ℃ and preserving heat for 2h, wherein the heating speed is 30 ℃/h, cooling to room temperature along with the furnace, and then discharging;

5) and (3) core trimming: carrying out surface powder blowing cleaning on the sintered ceramic core, and then detecting and modifying the shape by using a core measuring tool;

6) core strengthening: and putting the core into a container filled with ethyl silicate hydrolysate, then putting the container in a negative pressure environment to enable the ethyl silicate hydrolysate to permeate into pores of the core, keeping the soaking time for 2 hours, then putting the core on a frame to be dried for 24 hours, and finally drying the core for 2 hours at 150 ℃ to obtain the inorganic fiber composite silicon-based ceramic core.

The invention has the following beneficial effects:

according to the inorganic fiber composite silicon-based ceramic core and the preparation method thereof, the 3D printing technology and the ceramic fiber reinforced core material are successfully combined on the basis of the prior art, the advantages of the two are fully exerted, the good high-temperature mechanical property foundation is achieved, and the ceramic core biscuit with any shape, complexity and a precise structure can be easily prepared. According to the ceramic core prepared by the 3D printing technology, the ceramic core biscuit can be directly formed without designing and manufacturing a mold and undergoing the processes of mold closing, demolding and the like, so that the research and development and manufacturing periods are shortened, the product design freedom is high, errors occur, and the three-dimensional model size and the 3D printing technological parameters can be directly modified in a computer. Compared with the 3DP printing technology, the ceramic core prepared by the photocuring 3D printing process has low surface roughness and high dimensional precision, so the ceramic core has wide application prospect in the preparation of new generation turbine blades of aero-engines, and can be applied to directional solidification precision casting of the turbine blades of high-performance gas turbines.

Detailed Description

The invention is further described below by way of examples.