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Method for making alumina ceramic core and core leach method

A kind of technology of alumina ceramics and production methods, applied in the direction of core, casting mold, casting mold composition, etc., can solve the problems of small opening porosity, cracking of ceramic core, long time for core removal, etc., and achieve good creep resistance at high temperature , Improve the effect of core removal speed

Inactive Publication Date: 2008-07-30
NORTHWESTERN POLYTECHNICAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] After the above-mentioned alumina ceramic core is sintered, there is always a certain sintering shrinkage, which leads to cracking of the ceramic core due to the obstruction of burying and firing.
[0007] The core removal method for the above-mentioned alumina ceramic core is to directly dissolve the glass phase in the molten alkali to remove the core, and the high-temperature glass phase sintering makes the opening porosity of the traditional alumina ceramic core after sintering very small, and the molten alkali cannot enter Inside the ceramic core, the core removal process is the dissolution of the surface of the ceramic core, so the core removal time is long, and the core removal time is 25 to 30 hours

Method used

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  • Method for making alumina ceramic core and core leach method

Examples

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Comparison scheme
Effect test

Embodiment 1

[0028] Example 1: 75g of 180-mesh corundum powder, 265g of 250-mesh corundum powder and 290g of 325-mesh corundum powder were mixed with 150g of activated alumina and 30g of graphite powder by ball milling for 10 hours, and the ball-to-material ratio was 1:2.

[0029] Heat the plasticizer composed of 8g polyethylene, 22g beeswax and 160g paraffin to 60°C, gradually add it to the above-mentioned ball mixture, continue to stir and mix for 2 hours, and make alumina ceramic core plasticizer.

[0030] The above-mentioned plasticizer is pressed into a ceramic core according to the blade to be formed by hot pressing injection, and the hot pressing injection temperature is 50°C.

[0031] Fill the above-mentioned ceramic core in the sagger with alumina powder, and then pre-fire it; Heating to 1150°C, holding at 1150°C for 1 hour, and then cooling with the furnace.

[0032] The pre-fired ceramic core is taken out from the alumina powder for final firing. The final firing temperature is...

Embodiment 2

[0033] Example 2: 63g of 180-mesh corundum powder, 220g of 250-mesh corundum powder and 275g of 325-mesh corundum powder were mixed with 200g of activated alumina and 50g of graphite powder by ball milling for 20 hours, and the ball-to-material ratio was 1:2.

[0034] Heat the plasticizer composed of 10g polyethylene, 20g beeswax and 170g paraffin to 65°C, gradually add it to the above-mentioned ball mixture, continue stirring and mixing for 2.5 hours, and make alumina ceramic core plasticizer.

[0035] The above-mentioned plasticizer is pressed into a ceramic core according to the blade to be formed by hot pressing injection, and the hot pressing injection temperature is 55°C.

[0036] Fill the above ceramic core in the sagger with alumina powder, and then pre-fire; the pre-fire process is: rise from room temperature to 550°C within 5 hours, keep at 550°C for 4 hours, and then continue within 2.5 hours Heating to 1200°C, holding at 1200°C for 1.5 hours, and then cooling with ...

Embodiment 3

[0038] Example 3: 51 g of 180-mesh corundum powder, 255 g of 250-mesh corundum powder, 204 g of 325-mesh corundum powder, 300 g of activated alumina and 10 g of graphite powder were ball milled for 30 hours, and the ball-to-material ratio was 1:2.

[0039] Heat the plasticizer composed of 6g polyethylene, 27g beeswax and 147g paraffin to 70°C, gradually add it to the above-mentioned ball mixture, and continue to stir and mix for 3 hours to make alumina ceramic core plasticizer.

[0040] The above-mentioned plasticizer is pressed into a ceramic core according to the blade to be formed by hot pressing injection, and the hot pressing injection temperature is 60°C.

[0041] Use alumina powder to bury the above-mentioned ceramic core in a sagger, and then pre-fire; the pre-fire process is as follows: rise from room temperature to 600°C within 6 hours, keep at 600°C for 5 hours, and then continue within 3 hours Heat to 1100°C, hold at 1100°C for 2 hours, and then cool with the furna...

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Abstract

The invention discloses a method for manufacturing alumina ceramic cores, which adopts sintering of solid phase reaction, comprising two sintering methods of pre-sintering and final sintering; sintering temperature decreases to 1,350 to 1,500 DEG C from more than 1,500 DEG C in the prior art and creep resistance of high temperature is favorable. The invention also discloses a method for leaching the alumina ceramic cores. As in the process of the manufacture of the alumina ceramic cores, a volatile pore forming agent is adopted so that the forming alumina ceramic cores have relatively high porosity; in core leaching, melting alkali can reach the internal part of the alumina ceramic cores so as to integrally disperse the alumina ceramic cores. In the invention, a boiling water process and a repeated alkali cooking-dissolving- alkali cooking method are adopted, thus accelerating permeation, reaction and dissolving of the melting alkali to the internal part of the ceramic cores; the core leaching speed decreases to 10 to 16 hours from 25 to 30 hours in the prior art and the core leaching speed is accelerated.

Description

technical field [0001] The invention relates to a method for making an alumina ceramic core, and also relates to a method for removing the core from the alumina ceramic core. Background technique [0002] Alumina ceramic cores are used to form complex inner cavities of metal castings with high casting temperature and long solidification time, especially suitable for the production of superalloy turbine blades under the conditions of directional solidification and single crystal growth. [0003] The production of superalloy hollow blades has strict and contradictory requirements for the ceramic core used to form the inner cavity: one is to have good high temperature creep resistance; the other is to be soluble in acid or alkali to facilitate core removal. [0004] The known alumina ceramic core is made of β-Al 2 o 3 And glass phase additives to promote sintering, although it has excellent high temperature creep resistance, but the sintering temperature is higher than 1500 °...

Claims

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Application Information

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IPC IPC(8): C04B35/64C04B35/10B22C9/10
Inventor 成来飞张立同徐永东多贵英
Owner NORTHWESTERN POLYTECHNICAL UNIV
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