Silicon-based ceramic core preparation method

Abstract

The invention discloses a silicon-based ceramic core preparation method. The method comprises the following steps: powder configuration and mixing, slurry preparation, compression moulding and sintering, wherein the sintering step comprises the following processes: wax melting, gasification, intensified gasification, cristobalite transitional change, cristobalite change and final sintering. The silicon-based ceramic core prepared by using the preparation method is good in creep resistance, low in high temperature deflection, low in shrinking percentage, high in strength, high in porosity, and easy for core leach.

Description

technical field [0001] The invention relates to a ceramic core, in particular to a method for preparing a silicon-based ceramic core. Background technique [0002] The ceramic core is the abbreviation of a ceramic core used in the investment casting process. As an adapter to form the cavity of the casting, its function is to form the inner cavity structure of the casting, and together with the external mold and the mold shell, ensure the casting Dimensional accuracy requirements for the cavity. Ceramic cores are usually used to form the cavity of castings with complex shapes or difficult to form, as a special process method to simplify process difficulty, reduce cost and improve product qualification rate. [0003] 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, etc., and are widely used in hollow turbine blades, a...

AI Technical Summary

Problems solved by technology

When the content of cristobalite is low, the creep resistance of the ceramic core will be poor, and the ceramic core will soften and denature under the action of molten metal

Increasing the sintering temperature can increase the cristobalite content of the ceramic core after firing. If the final firing temperature is too low, the cristobalite conversion content of silica is too low, which will cause the core's room temperature strength and high temperature strength to be low.

[0027] Second: During the sintering process, if the temperature rises too fast, the conversion rate of cristobalite will be low, which will lead to the decrease of the high temperature deformation resistance of the ceramic core, the high temperature deflection, and the large shrinkage rate.

In the process of sintering the silicon-based ceramic core, dewaxing is required. If the temperature rises too fast, paraffin wax and beeswax will flow out quickly, and groove marks will flow on the silicon-based ceramic core body, which will reduce the inner cavity of the blade. Dimensional accuracy; if the dewaxing is not clean, it will cause cracks or even cracks in the ceramic core due to the gasification and expansion of paraffin wax and beeswax in the subsequent firing process