Method for preventing mixed crystal defect of single crystal blade based on laser heating technology

Abstract

The invention relates to the field of alloy directional solidification, in particular to a method for preventing a mixed crystal defect of a single crystal blade based on the laser heating technology. When a mold shell for single crystal blade production is prepared, on a back layer, slurry coating is independently carried out on a blade margin plate through slurry containing titanium diboride, and other mold shell preparation processes are not changed. In the directional solidification procedure of the single crystal blade, the position, where the mixed crystal defect is likely to occur and the margin plate is located, of the mold shell of the single crystal blade is subjected to laser heating, and by means of the effective absorption of the mold shell for laser energy, the margin plate of the single crystal blade is in a local heat preservation state. By means of the characteristics of high concentration and fast heating of the laser heating energy, the temperature of the margin plate is reasonably controlled when alloy of the margin plate of the single crystal blade is solidified, the situation that the margin plate is in a local supercooling state when close to a directional solidification thermal baffle region, then spontaneous nucleation occurs and the mixed crystal defect is caused is avoided, and thus smooth growth of single crystal is guaranteed.

Description

technical field [0001] The invention relates to the field of directional solidification of alloys, in particular to a method for preventing miscellaneous crystal defects in single crystal blades based on laser heating technology. Background technique [0002] With its superior performance, gas turbines were first widely used in the field of aero-engines. In order to improve the kinetic energy efficiency of aero-engines, people used superalloy directional solidification technology to make turbine blades into a single crystal form, which increased the high-temperature service life of the blades by dozens of times. , with the continuous advancement of gas turbine technology, in the last 30 years, the efficiency of industrial gas turbines has been greatly improved by applying the single crystal blade technology of aeroengines to the manufacture of large industrial gas turbine blades. Since the size of industrial internal combustion engines is much larger than aerospace blades, t...

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Problems solved by technology

Although this method can play a role of heat preservation to a certain extent, improve the temperature field distribution at the edge plate of the single crystal blade, and reduce the generation of miscellaneous crystals, but the strength of the bond between the ceramic fiber and the formwork is very low when the slurry is used. It is difficult to bond the ceramic fiber to the mold shell, and the last two layers of the mold shell are made of coarse sand, which makes the gap between the U-shaped insulation block and the mold shell inevitable, and the strength of the mold shell is difficult to be guaranteed.

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