Preparation method of mullite whisker reinforced aluminum-based ceramic core for directional solidification

A technology of mullite whiskers and ceramic cores, applied in the field of investment casting, can solve the problems of the adverse effects of high temperature creep resistance of cores, poor high temperature creep resistance, decreased high temperature strength, etc. High temperature creep performance, high open porosity, and the effect of reducing volume shrinkage

Inactive Publication Date: 2020-12-08
SHANGHAI JIAO TONG UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the silicon-based ceramic core mainly made of quartz glass has good alkali-solution core removal performance, its high-temperature creep resistance is poor, and it is prone to deformation and fracture during the directional solidification process of large-scale gas turbine blades
[0003] Aluminum-based ceramic cores based on alumina-based existing improved technologies have higher high-temperature resistance, but alumina has a high melting point, so some mineralizers are often added to aluminum-based ceramic cores to reduce the firing

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0028]Example 1

[0029]This embodiment includes the following steps:

[0030]Step 1. Surface treatment of lignin fiber

[0031]The lignin fiber is soaked in a silane coupling agent at a weight ratio of 1:20 and kept for 1 hour, and then the lignin fiber is dried at 120° C. for 24 hours to obtain a surface-modified lignin fiber for use.

[0032]Step two, mixing of ceramic core matrix materials

[0033]The raw materials of 75wt% fused corundum powder, 9wt% aluminum hydroxide powder, 2wt% yttrium oxide powder, 6wt% nano silica powder, 3wt% aluminum trifluoride powder, 5wt% lignin fiber Add it to the V-type mixer, perform forced mixing and dry mixing, and the mixing time is 1 hour to obtain the ceramic core matrix material, which is ready for use.

[0034]Step 3. Add a plasticizer composed of 55wt% semi-refined paraffin, 35wt% beeswax, 3wt% polyethylene and 7wt% oleic acid into the mixer; adjust the temperature of the mixer at 110°C, and wait for the plasticizer After all is melted, according to 80wt% o...

Example Embodiment

[0040]Example 2

[0041]This embodiment includes the following steps:

[0042]Step 1. Surface treatment of lignin fiber

[0043]The lignin fiber is soaked in the silane coupling agent at a weight ratio of 1:20 and kept for 1 hour, and then the lignin fiber is dried at 120° C. for 24 hours to obtain the surface-modified lignin fiber for use.

[0044]Step 2: Mixing of ceramic core matrix materials

[0045]80wt% fused corundum powder, 7.5wt% aluminum hydroxide powder, 3.5wt% yttrium oxide powder, 5wt% nano silica powder, 2wt% aluminum trifluoride powder, 2wt% lignin fiber Add the raw materials to the V-type mixer, perform forced mixing and dry mixing, and the mixing time is 1h to obtain the ceramic core matrix raw material, which is ready for use.

[0046]Step 3: Add a plasticizer composed of 70wt% semi-refined paraffin, 23wt% beeswax, 2wt% polyethylene and 5wt% oleic acid into the mixer; adjust the temperature of the mixer at 120°C, and wait for the plasticizer After all is melted, the ceramic core ma...

Example Embodiment

[0052]Example 3

[0053]This embodiment includes the following steps:

[0054]Step 1. Surface treatment of lignin fiber

[0055]The lignin fiber is soaked in the silane coupling agent at a weight ratio of 1:20 and kept for 1 hour, and then the lignin fiber is dried at 120° C. for 24 hours to obtain the surface-modified lignin fiber for use.

[0056]Step 2: Mixing of ceramic core matrix materials

[0057]Raw materials of 85wt% fused corundum powder, 5wt% aluminum hydroxide powder, 5wt% yttrium oxide powder, 3wt% nano silica powder, 1wt% aluminum trifluoride powder, 1wt% lignin fiber Add it to the V-type mixer, perform forced mixing and dry mixing, and the mixing time is 1h to obtain the ceramic core matrix material, which is ready for use.

[0058]Step 3. Add a plasticizer composed of 80wt% semi-refined paraffin, 15wt% beeswax, 1wt% polyethylene and 4wt% oleic acid into the mixer; adjust the temperature of the mixer at 130°C and wait for the plasticizer After all is melted, the ceramic core matrix raw...

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Abstract

The invention discloses a preparation method of a mullite whisker reinforced aluminum-based ceramic core for directional solidification. The preparation method comprises the following steps: mixing fused corundum powder used as raw material of ceramic core matrix, aluminum hydroxide powder, yttrium oxide powder, nano silicon dioxide powder, aluminum trifluoride powder and surface-treated lignin fibers for improving the porosity of the mold core, stirring and mixing with a molten plasticizer to obtain mold core slurry, and pressing to obtain a ceramic mold core blank; putting the ceramic core blank into magnesium oxide powder, carrying out four-stage sintering to burn off lignin fibers and improve the porosity, finally, carrying out impregnation with yttrium oxide sol, and then, carrying out roasting strengthening so that aluminum hydroxide and nano silicon dioxide in the ceramic core blank generate mullite whiskers in situ under the catalysis of aluminum trifluoride; therefore, the mullite whisker reinforced aluminum-based ceramic core for directional solidification of turbine blades of aero-engines and gas turbines is obtained. The obtained ceramic core can bear the high temperature of 1,550-1,700 DEG C in the directional solidification process of hollow turbine blades of large-size aero-engines and gas turbines, is small in deformation and does not crack under the high temperature gradient.

Description

technical field [0001] The invention relates to a technology in the field of investment casting, in particular to a method for preparing a mullite whisker-reinforced aluminum-based ceramic core for directional solidification of aeroengines and gas turbine blades. Background technique [0002] The role of the ceramic core is to form the inner cavity of the hollow blade of the aero-engine and gas turbine, and together with the investment pattern and the shell to ensure the dimensional accuracy of the wall thickness of the hollow blade, after the blade is formed, the core is removed by mechanical or chemical methods, that is A hollow structure of the blade can be obtained. The ceramic cores used in the precision casting of hollow blades of aero-engines and gas turbines are large in size and complex in shape, and the requirements for mechanical properties such as high-temperature strength and high-temperature creep resistance are much higher than those of ordinary small ceramic ...

Claims

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Application Information

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IPC IPC(8): C04B35/10C04B35/81B22C9/10C04B38/06C04B41/85C04B35/64
CPCB22C9/10C04B35/10C04B35/64C04B38/0675C04B41/5045C04B41/85C04B2235/3206C04B2235/3225C04B2235/3418C04B2235/445C04B2235/5224C04B2235/661C04B2235/96C04B38/0074
Inventor 李飞马鑫雷四雄胡兵易出山汪东红孙宝德
Owner SHANGHAI JIAO TONG UNIV
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