Preparation method for precision-investment casting mold shell of easily-oxidized metals

Abstract

The invention provides a precision-investment casting method for easily-oxidized metals. The precision-investment casting method comprises the following steps of (1) preparation of a surface layer of a mold shell, specifically, a refractory powder is added into a binder and evenly mixed, a wetting agent and an antiforming agent are further added, and even mixing is conducted to prepare surface layer coating; and the coating is smeared on a wax patter, and after drying, the above operations are repeated for many times to form a surface layer mold shell; (2) preparation of a reinforcement layer of the mold shell, specifically, a bauxite powder is added into a silica sol binder and evenly mixed, bauxite sand is adopted to conduct stuccoing, and after drying, the above operations are repeated for many times to form a reinforcement layer mold shell; (3) mold shell dewaxing and roasting, specifically, an infrared dewaxing technology is adopted; and (4) melting and pouring, a vacuum consumable kish melting method is adopted to conduct melting, and a centrifugal pouring technology is adopted to conduct pouring. According to the precision-investment casting method for easily-oxidized metals, a casting produced by adopting the method is precise in size, the minimum wall thickness is small than or equal to 1.0 mm, the surface roughness is smaller than or equal to 6.3 mu m, the surface reaction layer is smaller than or equal to 0.03 mm, and the surface is free of the defects of cold shut, flow marks, microcracks and the like; and moreover the production cost is reduced, the production cycle is shortened, and the method is suitable for volume production.

Description

technical field [0001] The invention relates to a process method for preparing investment casting mold shells for easily oxidized metals. Background technique [0002] Easily oxidizable metals (titanium, zirconium, etc.) have the characteristics of low density, high specific strength, and corrosion resistance, and have been widely used in aviation, aerospace, nuclear energy, chemical, and medical industries. Easily oxidizable metals have high activity in the molten state, and can chemically react with commonly used refractory materials to varying degrees, and can also react with O 2 , N 2 、H 2 and CO 2 And other gases have chemical reactions, affecting the quality of castings. Therefore, the casting technology of easily oxidized metals has high requirements on casting materials and casting equipment, and appropriate casting materials and casting methods must be selected to ensure the quality of castings. [0003] At present, the oxidizable metal casting technology mainl...

AI Technical Summary

Problems solved by technology

However, there are certain problems in this process technology. On the one hand, the yttrium oxide material is relatively expensive, resulting in high production costs. On the other hand, the yttrium sol binder has poor stability during the preparation process and is prone to gelation. Zirconium acetate binder The gelling speed is slow and reversible during the shell making process. After gelling, it will "dissolve" when it encounters water, and it will fall off from the wax mold. Therefore, the shell needs a long drying time, resulting in a mold preparation cycle. longer