A kind of composite coating molding preparation method of ceramic core

Abstract

The purpose of the present invention is to provide a preparation process of a ceramic core and superalloy cavity structure casting, wherein the preparation process of the ceramic core is: dividing the inner cavity into left and right half cavities at the maximum section of the casting inner cavity Structure, prepare the left and right half-core wax molds that are completely consistent with the shape and size of the internal cavity structure of the casting, and the inner dimensions corresponding to the concave parts of the left and right half-core wax molds are exactly the same as the outer structure dimensions of the ceramic core; The left and right half-model cores are prepared by the precision casting process. After the half-model cores are dried, they are dewaxed and roasted. After sintering, the largest cross-sections of the left and right half-model cores are trimmed. Negative tolerances are reserved for the left and right trimmed surfaces; bonding is used The left and right half-mold ceramic cores are combined into a monolithic ceramic core, and then dried for 4-8 hours to obtain a ceramic core for superalloy castings. The method can improve the comprehensive performance of the ceramic core, simplify the preparation process and process, ensure the matching between the core and the mold shell and reduce the casting cost.

Description

technical field [0001] The invention belongs to the technical field of high-temperature alloy precision casting, and particularly provides a preparation method of a ceramic core. Background technique [0002] High-temperature alloy precision castings are widely used in power generation, power industry and other fields. Such castings usually have complex inner cavity structures, which cannot be directly produced by traditional precision casting processes. Usually, ceramic cores are used to form the inner cavity structure, and then chemical methods are used. The core is removed, and finally the cavity of the casting is formed. [0003] At present, ceramic cores are mostly alumina-based or silica-based materials, and the powder particles are relatively fine (greater than 200 mesh). They are often prepared by powder mixing, slurry preparation, injection molding and sintering processes. The process is cumbersome and lengthy. , there are certain process difficulties and deficienc...

AI Technical Summary

Problems solved by technology

[0003] At present, ceramic cores are mostly alumina-based or silica-based materials, and the powder particles are relatively fine (greater than 200 mesh). They are often prepared by powder mixing, slurry preparation, injection molding and sintering processes. The process is cumbersome and lengthy. , there are certain process difficulties and deficiencies, such as the core is easily deformed during the injection molding and sintering process, and the core shrinks after sintering, resulting in out-of-tolerance or unqualified dimensions, etc.

In addition, during the use process, due to the large performance difference between the ceramic core and the mold shell, the core is often bent or broken, which leads to a significant increase in the cost of castings and the scrap rate

For castings with multiple small through-hole cross-sections and large concave cavity structures, the ordinary precision casting process cannot guarantee the accurate molding of the inner cavity

The normal coating, sanding and other processes used in the literature (coating core precision casting hollow blade castings, pages 11-13, "Special Casting and Nonferrous Alloys, Issue 1, 1994") have certain limitations. , if only the inner cavity is not very narrow, it is required that the internal cooling channel of the casting must be in a straight-through shape without twists and turns, and the length of the inner cavity is short and less than 100mm, otherwise it cannot be guaranteed to coat the central part

At the same time, it is very difficult to remove the corundum type core after pouring

Castings with multiple small through-hole cross-sections and large concave cavity structures cannot be prepared using the processes in the above literature

However, the preparation of ceramic cores by injection molding has low efficiency, high cost and limited performance. Therefore, it is necessary to develop a new process to prepare such structural castings.

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