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Silicon-base ceramic core added with cristobalite

A technology of ceramic cores and additives, applied in the direction of cores, molds, and mold components, can solve the problem of failure to meet the requirements of directional casting of blades, high temperature creep resistance has not been reported, and deterioration of ceramic cores. Core performance and other issues, to achieve the effect of improving high temperature creep resistance, improving high temperature creep resistance, and improving high temperature deformation resistance

Inactive Publication Date: 2011-09-14
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If the shrinkage rate of the ceramic core is too large, the dimensional accuracy of the inner cavity of the blade will be reduced; and the reduction of the porosity will deteriorate the core removal performance of the ceramic core
Therefore, the existing silicon-based ceramic cores cannot meet the requirements of directional casting of blades, and become a technical bottleneck restricting the development of hollow turbine blades. It is necessary to research and develop silicon-based ceramic cores with excellent performance.
[0004] At present, there are no reports at home and abroad on improving the high temperature creep resistance and dimensional stability of ceramic cores by pre-adding cristobalite.

Method used

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  • Silicon-base ceramic core added with cristobalite
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  • Silicon-base ceramic core added with cristobalite

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] The ceramic core composition is 74% quartz glass, 10% cristobalite, and 16% zirconia. The purity of the quartz glass is greater than or equal to 99.59%, and the purity of zirconia is greater than or equal to 99.96%. The cristobalite is calcined from quartz glass and pressed into a standard sample. Sample. According to the process, the temperature is raised to 1250 ° C for 4 hours, and after roasting, it is strengthened with ethyl silicate aqueous solution and epoxy resin / polyamide. X-ray quantitative analysis shows that the amount of cristobalite in the ceramic core is 21%. Compared with the ceramic core without adding cristobalite, the crystallization rate is obviously increased, and the high temperature deformation resistance is improved. The performance index of the core is as follows: the bending strength at room temperature is 73MPa, the high temperature deflection (30min at 1550°C) is 16mm, and the shrinkage rate is 2.3%.

Embodiment 2

[0039] The ceramic core composition is 74% quartz glass, 10% cristobalite, and 16% zirconia. The purity of the quartz glass is greater than or equal to 99.59%, and the purity of zirconia is greater than or equal to 99.96%. The cristobalite is calcined from quartz glass and pressed into a standard sample. Sample. According to the process, the temperature is raised to 1300 ° C for 4 hours, and after roasting, it is strengthened with ethyl silicate aqueous solution and epoxy resin / polyamide. X-ray quantitative analysis shows that the amount of cristobalite in the ceramic core is 40%. Compared with the ceramic core in Example 1, the amount of cristobalite transformation increases, indicating that the increase in sintering temperature is beneficial to the crystallization of quartz glass. The ability of the core to resist high temperature deformation is greatly improved. The performance index of the core is as follows: the bending strength at room temperature is 72MPa, the high tem...

Embodiment 3

[0041] The ceramic core composition is 44% quartz glass, 40% cristobalite, and 16% zirconia. The purity of the quartz glass is greater than or equal to 99.59%, and the purity of zirconia is greater than or equal to 99.96%. The cristobalite is calcined from quartz glass and pressed into a standard sample. Sample. According to the process, the temperature is raised to 1250 ° C for 4 hours, and after roasting, it is strengthened with ethyl silicate aqueous solution and epoxy resin / polyamide. X-ray quantitative analysis shows that the amount of cristobalite in the ceramic core is 47%. Compared with the ceramic core without adding cristobalite, the crystallization rate is significantly increased, and the high temperature deformation resistance is significantly improved. The performance index of the core is as follows: the bending strength at room temperature is 60MPa, the high temperature deflection (30min at 1550°C) is 0.6mm, and the shrinkage rate is 1.14%.

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Abstract

A silicon-base ceramic core added with cristobalite consists of the following components: quartz glass, cristobalite and zirconium oxide. In the invention, the cristobalite is added to the ceramic core; therefore, on one hand, the crystallization of the quartz glass can be promoted by using the cristobalite so that the ceramic core contains enough cristobalite after being burned as the crystallization crystal core of the quartz glass before alloy liquid pouring and a great deal of cristobalite crystals in the ceramic core become into a high-temperature resistant frame; the high-temperature creep resistance of the ceramic core is improved; and the high temperature deformation of the ceramic core is effectively reduced, and the non-core exposure rate of the directional casting blade is improved; on the other hand, the characteristic such as the viscosity flow of the quartz glass can be restrained during the roasting process of the ceramic core by using the cristobalite; the size of the ceramic core is stabilized; the contractibility rate of the ceramic core is reduced; and the precision of the internal chamber of the blade is improved. The invention provides the silicon-base ceramic core with excellent performance for directional hollow turbine blade and other precise casting fields.

Description

technical field [0001] The invention discloses a silicon-based ceramic core added with cristobalite, in particular to a silicon-based ceramic core for directional hollow turbine blades added with cristobalite; it belongs to the technical field of precision casting. Background technique [0002] Silicon-based ceramic cores have the advantages of small expansion coefficient, excellent resistance to rapid cooling and rapid heating, high mechanical strength, good chemical stability and easy core removal, and are widely used in the field of hollow turbine blade manufacturing. Silicon-based ceramic cores use quartz glass as the base material, and generally add alumina, mullite, and zircon as mineralizers. By selecting an appropriate sintering temperature, the content of cristobalite in the ceramic core is controlled to improve the shape. core performance. This type of ceramic core has a high yield rate when pouring equiaxed crystal blades with low temperature, but when it is orie...

Claims

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Application Information

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IPC IPC(8): B22C9/11B22C1/00B22C1/02
Inventor 刘志义龙永成韩向楠王荣峰夏琳燕
Owner CENT SOUTH UNIV
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