Ceramic shell for inhibiting sands sticking on surface of high-temperature alloy turbine blades and preparation method thereof

A technology of turbine blades and high-temperature alloys, which is applied in the field of precision casting, can solve the problems of reduced productivity, scrapped blades, recrystallization of the surface of blades with out-of-tolerance dimensions, and achieve the effects of reducing sand sticking and increasing strength

Active Publication Date: 2019-06-21
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The high-temperature chemical reaction between the active elements in the alloy and the shell mainly includes the decomposition of ceramic oxides and the replacement reaction between ceramic oxides and alloy melts, and the products are metal oxides and gases, which result in the formation of chemical oxides on the surface of the blades. The sticky sand defect changes the surface composition of the blade, deteriorates the surface quality of the blade, makes it difficult to shell and even scraps the blade; on the other hand, the serious chemical sticky sand layer on the blade surface is difficult to remove by ordinary mechanical methods, so the blade has to Casting with a margin, and removing the sticky sand layer through subsequent machining, not only caused an increase in the production cost of the blade and a decrease in productivity, but also buried hidden dangers for the formation of defects such as blade size out-of-tolerance and surface recrystallization

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Step 1, prepare the surface coating of the ceramic shell:

[0033] Weigh 20kg of silica sol with a particle content of 25wt% and a pH value of 8, add it to the slurry mixing tank, start the mixer, and add 75kg of silica sol with a particle size of 320 mesh and α~Al 2 o 3 Fused corundum powder with a content of 99.0 wt%, 1 kg of hexagonal boron nitride (purity ≥ 99.0 wt%, free boron content below 0.5 wt%, particle size of 1 μm), 0.8 kg of calcined kaolin with a particle size of 1 μm, 0.2 kg Titanium dioxide with a particle size of 0.5 μm, 2.5 kg of polyvinyl acetate emulsion with a solid content of 25 wt %, and 0.125 kg each of wetting agent, defoamer, dispersant and preservative, stirred for 2 hours, and the measured viscosity was 20 s (No. 5 Zahn cup ), then transfer the topcoat to the L-shaped dip bucket.

[0034] Step 2, preparing the ceramic shell:

[0035] Dip the cleaned and blown-dried wax pattern into the above prepared surface coating, let the coating hang o...

Embodiment 2

[0040] Step 1, prepare the surface coating of the ceramic shell:

[0041] Weigh 25kg of silica sol with a particle content of 30wt% and a pH value of 8.5, add it to the slurry mixing tank, start the mixer, and add 69kg of silica sol with a particle size of 325 mesh and α~Al 2 o 3Fused corundum powder with content ≥99.0wt%, 15kg hexagonal boron nitride (purity ≥99.0wt%, free boron content less than 0.5wt%, particle size 5μm), 1.2kg calcined kaolin with particle size 20μm, 0.3kg Particle size is the titanium dioxide of 20 μm, 2kg solid content is the latex of 30wt%, and each 0.125kg of wetting agent, defoamer, dispersant and preservative, stir 7h, measure viscosity and be 25s (No. 5 Zahn cup), then put The top coat is transferred to the L-shaped dip bucket.

[0042] Step 2, preparing the ceramic shell:

[0043] Dip the cleaned and blown-dried wax pattern into the above prepared surface coating, let the coating hang on the wax pattern evenly, and then evenly sprinkle the 90-me...

Embodiment 3

[0048] Step 1, prepare the surface coating of the ceramic shell:

[0049] Weigh 30kg of silica sol with a particle content of 35wt% and a pH value of 9, add it to the slurry mixing tank, start the mixer, and add 60kg of silica sol with a particle size of 330 mesh and α~Al 2 o 3 Fused corundum powder with content ≥99.0wt%, 4kg hexagonal boron nitride (purity ≥99.0wt%, free boron content less than 0.5wt%, particle size 10μm), 3.2kg calcined kaolin with particle size 38μm, 0.8kg Particle size is 38 μm titanium dioxide, 1.5kg solid content is the polyvinyl acetate latex of 35wt%, and each 0.125kg of wetting agent, defoamer, dispersant and bactericide, stir 12h, measure viscosity and be 35s (No. 5 Zahn cup ), and then transfer the topcoat to the L-shaped dipping bucket.

[0050] Step 2, preparing the ceramic shell:

[0051] Dip the cleaned and blown-dried wax pattern into the above prepared surface coating, let the coating hang on the wax pattern evenly, and then evenly sprinkle...

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Abstract

The invention discloses a preparation method of a ceramic shell for inhibiting sands sticking on a surface of high-temperature alloy turbine blades. The preparation method comprises the following steps: 1, preparing surface coating of the ceramic shell, adding fused corundum powder, composite powder of hexagonal boron nitride, calcined kaolin and titanium dioxide, latex, wetting agent, defoaming agent, dispersing agent and preservative into silica solution under a stirring state, and continuously stirring for 2-12 hours to obtain the surface coating of the ceramic shell; and 2, preparing the ceramic shell. The invention further discloses the ceramic shell for inhibiting the sands sticking on the surface of the high-temperature alloy turbine blades. Chemical sand sticking caused by wetting-reaction can be inhibited by the ceramic shell, and the sand sticking caused by mechanical heat penetration of the metal melt can be reduced.

Description

technical field [0001] The invention relates to the technical field of precision casting, in particular to a ceramic shell for suppressing sand sticking on the surface of a superalloy turbine blade and a preparation method thereof. Background technique [0002] During the directional solidification investment casting process of superalloy turbine blades, the element diffusion and wettability of the solid-liquid two-phase interface between the alloy melt and the ceramic shell are closely related to the alloy composition, ceramic composition, and surface roughness of the shell. . The shell surface layer has a porous structure. Under the static pressure of the alloy melt during pouring, the melt easily penetrates into the pores of the shell surface layer. After solidification and cooling, metal burrs surrounding the sand particles are formed on the surface of the blade. At the same time, the mixture of alloy and sand particles will also firmly adhere to the surface of the blad...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22C3/00B22C1/02B22C9/04
Inventor 李飞孙宝德
Owner SHANGHAI JIAO TONG UNIV
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