Auxiliary technique capable of increasing graphite mould titanium alloy casting quality

Abstract

The invention relates to an auxiliary process for improving quality of a graphite type titanium alloy casting, which comprises the following steps: before pouring, using Y2O3, adhesive and deionized water to prepare surface slurry for accurately casting titanium according to a ratio of 85:10:5, using a thin brush to evenly coat the surface slurry on the surface of a graphite type core for forming the casting during pouring till fully covering, roasting the graphite type core in vacuum at a temperature of between 900 and 1,000 DEG C after the graphite type core is placed for 1 hour, preserving heat for 2 to 4 hours at a vacuum degree of less than or equal to 10Pa, cooling the graphite type core to be below 300 DEG C along with cooling of a furnace, discharging the graphite type core and then preserving heat at a temperature of between 100 and 200 DEG C in a baking oven, and taking out the graphite type core for standby during pouring. The auxiliary process can use the special surface slurry to fill pores on the surface of graphite, prevents the graphite from attaching to the surface of the casting after pouring, reduces the defects of cold lap, flow mark and the like generated on the surface of the casting, and increases tendency to forming gross shrinkage by the casting.

Description

technical field [0001] The invention belongs to the technical field of casting technology, and in particular relates to an auxiliary process for improving the quality of graphite-type titanium alloy castings. Background technique [0002] The existing cast titanium alloy molding process is mainly organic processing graphite type process and investment precision casting process. The molding material of machining graphite type process is artificial graphite, and the molding material of investment precision casting is mainly oxide ceramic shell, such as zirconia and yttrium oxide. [0003] The machined graphite type process method is to machine the artificial graphite rod or plate into a cavity consistent with the shape of the casting, and pour it after high-temperature roasting. Artificial graphite is not eroded by molten titanium, has good thermal shock resistance, good high temperature stability, strong resistance to deformation, and low cost. It is widely used in the casti...

AI Technical Summary

Problems solved by technology

[0004] 1. Due to the good thermal conductivity of artificial graphite, coupled with the characteristics of low specific heat and easy solidification of titanium, defects such as cold shut and flow marks often occur on the surface of titanium castings, resulting in a decrease in the surface quality of titanium castings, resulting in post-processing of titanium castings (repair welding, welding, etc.) Grinding and trimming) increased difficulty and workload

[0005] 2. The graphite type has high strength and poor yield, and micro-cracks are easy to occur on the casting surface

[0006] 3. The internal density of artificial graphite is poor, and there are pores. Graphite is easy to adhere to the surface of titanium castings after pouring, which is difficult to clean

[0007] 4. The graphite type is not suitable for machining. The structural part needs to be processed manually with a foundry shovel and a file. After processing, it is difficult to ensure smoothness at the knife marks, resulting in a decrease in roughness and difficult to ensure dimensional tolerances.

This process overcomes the shortcomings of the machining graphite process, but it needs to make professional molds, resulting in increased costs when pouring single pieces and small batches of castings; and its existing oxide ceramic shell has low strength, and it is difficult to cast large titanium castings. The shell is easy to crack, causing water to run out and even the casting to be scrapped