阅读说明：本技术 一种锤击和切削复合去除损伤环境障涂层的喷砂层剥方法 (sandblasting layer stripping method for removing damaged environmental barrier coating by combination of hammering and cutting ) 是由 杨冠军 李广荣 刘梅军 杨博 李成新 李长久 于 2019-11-07 设计创作，主要内容包括：本发明公开一种锤击和切削复合去除损伤环境障涂层的喷砂层剥方法,首先,筛选硬度小于基体且大于涂层材料的砂粒材料；其次,采用500～1000μm的粗砂通过依次变化攻角在涂层表面形成锤击/切削的复合作用,达到逐层剥落涂层、且使70％的基体表面裸露的目的；最后采用50～450μm的细砂以0°～30°的攻角冲蚀涂层,以去除局部的残留涂层,达到95％以上的基体面积裸露的目的。本发明所提出的基于锤击/切削复合作用的损伤环境障涂层的喷砂层剥去除方法,可在不损伤基体的前提下,有效去除损伤的环境障涂层,以确保高质量新涂层的制备。(The invention discloses a sandblasting layer stripping method for removing damaged environmental barrier coatings by combining hammering and cutting, which comprises the steps of screening sand grain materials with hardness smaller than that of a matrix and larger than that of a coating material, forming a hammering/cutting combined action on the surface of the coating by sequentially changing an attack angle by using 500-1000 mu m coarse sand to achieve the purposes of peeling off the coating layer by layer and exposing 70% of the surface of the matrix, and finally eroding the coating by using 50-450 mu m fine sand at the attack angle of 0-30 degrees to remove partial residual coatings to achieve the purpose of exposing more than 95% of the area of the matrix.)

The sandblasting layer stripping method for removing the damaged environmental barrier coating by combining hammering and cutting is characterized by comprising the following steps of:

step 1, using sand to attack angle α₁Eroding the damaged environment barrier coating (5) until pits and bulges are formed on the upper part of the damaged environment barrier coating (5);

step 2, using sand grains to attack angle α₂Erosion damaging the environmental barrier coating (5) until the pits and lands formed in step 1 are removed, the angle of attack α₂Specific angle of attack α₁At least 60 degrees smaller;

step 3, repeating the step 1 to the step 2 until the surface of the matrix (4) is exposed by more than or equal to 70 percent;

step 4, using sand to attack angle α₂The environmental barrier coating (5) is eroded until more than or equal to 95 percent of the surface of the matrix is exposed;

in steps 1 to 4, the hardness of the selected sand grains is greater than the hardness of the damage environment barrier coating (5) and less than the hardness of the matrix (4).

2. The blast stripping method for combined peening and cutting removal of damaged environmental barrier coating as claimed in claim 1,the angle of attack α₁Is 60 degrees to 90 degrees, and the attack angle is α degrees₂Is 0 to 30 degrees.

3. The grit blasting delamination method for removing damaged environmental barrier coating by combined hammering and cutting as set forth in claim 1, wherein in steps 1-4, the material of said grit is Al₂O₃Or SiO₂。

4. The grit blasting delamination method for composite peening and cutting removal of damaged environmental barrier coating as claimed in claim 1, wherein said grit used in Steps 2 and 4 is polygonal and said grit used in step 1 is spherical.

5. The blasting delamination method for removing damaged environmental barrier coating by combined hammering and cutting as claimed in claim 1, wherein in steps 1-4, the damaged environmental barrier coating (5) is eroded by a blasting machine with blast air pressure of 0.1-0.5 MPa and particle velocity of 30-80 m/s.

6. The grit blasting delamination method for composite peening and cutting removal of damaged environmental barrier coating as claimed in claim 1, wherein the grit sizes used in step 1 and step 2 are the same, and the grit size used in step 4 is 10% -45% of the grit size used in step 1.

7. The abrasive blasting delamination method for removing damaged environmental barrier coating by composite hammering and cutting methods according to claim 1 or claim 6, wherein the grit sizes used in step 1 and step 2 are 500 μm to 1000 μm, and the grit size used in step 4 is 50 μm to 450 μm.

Technical Field

The invention belongs to the technical field of coatings, and particularly relates to a high-efficiency nondestructive removing method for damaged environmental barrier coatings.

Background

The current major research is continuous fiber reinforced ceramic matrix composite materials, mainly carbon fiber reinforced silicon carbide (C)_fSilicon carbide (SiC) reinforced by silicon carbide fiber_fSiC) and oxide/oxide ceramic matrix composites.

However, the surface stability of the ceramic matrix composite material with good stability in dry environment is drastically deteriorated in the working environment of the engine, which is caused by the layers of dense and stable SiO formed on the surface of the ceramic matrix composite material in the high temperature dry environment₂The material can be protected from further oxidation and has good surface stability, while when the environment contains water vapor, SiO₂Reacting with steam to generate Si (OH) easy to volatilize₄EBC refers to a protective coating ( is an oxide or oxide mixture ceramic coating) on the surface of a high-temperature structural material used in the engine environment, and the coating can establish barriers between the high-temperature structural material and the severe environment (corrosive cutoff, high-speed airflow scouring and the like) of the engine to prevent or reduce the influence of the engine environment on the performance of the high-temperature structural material.

However, under the high-temperature gas high-speed scouring environment of an aircraft engine, the EBC after being in service for periods often has the damage problems of peeling and the like, if the EBC is not maintained in time, the expensive ceramic matrix composite can be discarded for times, and even severe accidents are caused in subsequent continuous use.

Disclosure of Invention

The invention aims to provide an sandblasting layer stripping removal method for damaged environmental barrier coatings, aiming at effectively removing the damaged coatings on the premise of not damaging a substrate.

In order to achieve the purpose, the invention adopts the following technical scheme:

A blasting layer stripping method for removing damaged environmental barrier coating by hammering and cutting, comprising the following steps:

step 1, using sand to attack angle α₁Eroding the damaged environment barrier coating until pits and bulges are formed on the upper part of the damaged environment barrier coating;

step 2, using sand grains to attack angle α₂Erosion damage to the environmental barrier coating until the pits and bumps formed in step 1 are removed, the angle of attack α₂Specific angle of attack α₁At least 60 degrees smaller;

step 3, repeating the step 1 to the step 2 until the surface of the matrix is exposed by more than or equal to 70 percent;

step 4, using sand to attack angle α₂Eroding and damaging the environmental barrier coating until more than or equal to 95 percent of the surface of the matrix is exposed;

in steps 1-4, the hardness of the selected sand is greater than the hardness of the damaged environmental barrier coating and less than the hardness of the matrix.

step forward, angle of attack α₁Is 60 degrees to 90 degrees, and the attack angle is α degrees₂Is 0 to 30 degrees.

, in steps 1-4, the material of the sand grains is Al₂O₃Or SiO₂。

Further , the sand used in step 2 and step 4 is polygonal and the sand used in step 1 is spherical.

And , in the steps 1 to 4, a sand blasting machine is used for eroding the damaged environment barrier coating, the sand blasting air supply pressure is 0.1MPa to 0.5MPa, and the particle speed is 30m/s to 80 m/s.

, the sand grains used in step 1 and step 2 have the same grain size, and the grain size of the sand grain used in step 4 is 10% -45% of the grain size of the sand grain used in step 1.

, the sand grains used in step 1 and step 2 have a grain size of 500-1000 μm and the sand grains used in step 4 have a grain size of 50-450 μm.

Compared with the prior art, the invention has the following beneficial effects:

the invention discloses a sandblasting layer stripping method for removing damaged environmental barrier coatings by combining hammering and cutting, which comprises the steps of firstly selecting sandblasting hardness to enable the hardness of the sandblasting hardness to be lower than that of a substrate and higher than that of the damaged environmental barrier coatings, so that the substrate is not damaged in the process of removing the damaged environmental barrier coatings by sandblasting, secondly forming a combined hammering and cutting effect on the surfaces of the damaged environmental barrier coatings alternately by adjusting the attack angle of coarse sand grains to achieve the purpose of removing the damaged environmental barrier coatings by peeling layer by layer along the thickness direction, and achieving the purpose of removing more than 70% of the damaged environmental barrier coatings, and finally removing residual micro local areas by layer stripping through the cutting effect of fine sand grains under a small attack angle, so that more than 95% of residual coatings are effectively removed, and high-quality deposition of subsequent new coatings is ensured.

, in steps 1-4, the material of the sand grains is Al₂O₃Or SiO₂The two materials have low cost, moderate hardness and wider engineering application range of .

, the grit used in step 1 is preferably spherical to provide a hammering effect on the damaged environmental barrier coating surface and the grit used in steps 2 and 4 is preferably multi-faceted to provide a cutting effect on the damaged environmental barrier coating at low angles.

, in the steps 1 to 4, a sand blasting machine is used for eroding the damaged environment barrier coating, the sand blasting air supply pressure is 0.1-0.5 MPa, the particle speed is 30-80 m/s, the sand blasting air supply pressure is 0.1-0.5 MPa, the damage to the matrix is avoided, the efficiency of removing the damaged environment barrier coating can be guaranteed, the pressure is too high, the matrix is easily damaged, the pressure is too low, and the removal efficiency is low.

, the sand grains used in step 1 and step 2 have the same grain size, the grain size of the sand grain used in step 4 is 10% -45% of the grain size of the sand grain used in step 1, the aspect of using small grain size is to make the sand grain effectively contact with the residual micro-area so as to fully remove the residual micro-area, and the aspect of is to increase the quantity of small grain size sand grains under the same quality, increase the impact frequency of the sand grain and the residual micro-area, and also be beneficial to removing the residual micro-area.

Drawings

FIG. 1 is a schematic view of a blast-blasted damaged environmental barrier coating of the present invention;

FIG. 2 is a schematic cross-sectional view of an initial state of a damaged environmental barrier coating;

FIG. 3 is a schematic view of a peening/cutting composite based abrasive blasting damage removal coating;

in the drawings: 1-nozzle, 3-sand blasting beam current, 4-matrix, 5-damage environment barrier coating, 6-sheet layer and 7-interlayer pore crack.

Detailed Description

The following are specific examples given by the inventor, and it should be noted that these examples are preferable examples of the present invention and are used for understanding the present invention by those skilled in the art, but the present invention is not limited to these examples.

Referring to fig. 2, the damage environment barrier coating 5 on the substrate 4 comprises a plurality of stacked sheets 6 with interlayer pore cracks 7 between adjacent sheets 6.