Artificial preparation method of multi-scale aero-engine environment sediment particles

Abstract

The invention belongs to the technical field of thermal barrier coatings, and provides an artificial preparation method of multi-scale aero-engine environment sediment particles. The preparation method comprises the following steps: grinding CMAS original powder into mixture powder; calculating the mass of the required mixture powder according to the powder density of the CMAS original powder and the particle size of the target sediment particles; weighing the mixture powder, and pressing the mixture powder into sheets; in an air suspension furnace, tabletting and melting the mixture powder into balls by adopting a laser; and rapidly cooling to normal temperature to obtain the target sediment particles with the target particle size. The melting process of the CMAS powder is greatly improved, the gas suspension furnace and the laser are used for heating, single CMAS particles with the designed size can be obtained in a short time, the preparation time is shortened, and the preparation cost is effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of thermal barrier coatings, and in particular to an artificial preparation method for multi-scale aviation engine environmental sediment particles. Background Art

[0002] In the application of modern aircraft engines and gas turbines, the high temperature resistance and corrosion resistance of thermal barrier coating materials are crucial, especially in harsh high temperature environments, where these coatings are subjected to extremely high stress and thermal strain. However, with the continuous increase in operating temperature, corrosion problems caused by environmental sediments such as sand, dust and volcanic ash in the atmosphere (mainly composed of CaO-MgO-AlO-SiO, referred to as CMAS) have become one of the main factors for the failure of thermal barrier coatings. CMAS will melt at high temperatures and spread to the surface of the thermal barrier coating and penetrate into the interior, resulting in local peeling and cracking of the coating, or even failure of the entire coating system. Therefore, studying the behavior of CMAS particles at high temperatures is crucial to improving the corrosion resistance of the coating and extending its service life.

[0003] In the prior art, CMAS with different component contents are usually prepared by high-temperature melting method and melt cooling method. An appropriate amount of CMAS original powder is selected and placed in a crucible, and then the crucible is placed at high temperature until the powder completely becomes molten, and the melt is cooled at a faster rate under certain supercooling conditions to form glass. Finally, the obtained glass is crushed and ground to prepare CMAS powder with relatively uniform composition. In order to study the high-temperature behavior of CMAS, most of the current schemes are to press the prepared CMAS powder into a block of a certain size and place it on the surface of the thermal barrier coating material, and then observe the morphological changes of the sample in a high-temperature environment and test the spreading area, penetration layer thickness and other data after CMAS melting at different temperatures.

[0004] However, the above method also has many obvious problems. First, during the high-temperature melting process, due to the long time, the sample may have serious volatilization and severe component segregation. In addition, since the melt is contained in a crucible, the induced nucleation problem caused by the inevitable contact between the crucible wall and the melt greatly restricts the glass forming ability. It is worth noting that the thermodynamic behavior of CMAS particles of different particle sizes and the melting dynamics at high temperatures are significantly different. The method of pressing powder into blocks cannot observe the high-temperature behavior of a single particle at all. Therefore, it is crucial to develop a preparation method that can obtain single CMAS particles with uniform composition and different particle sizes for studying the high-temperature properties of CMAS. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention proposes a method for artificially preparing multi-scale aerospace engine environmental sediment particles. The preparation method has made significant improvements on the melting process of CMAS powder, using an air suspension furnace and a laser for heating, and can obtain single CMAS particles of designed size in a short time, which not only shortens the preparation time, but also effectively reduces the preparation cost.

[0006] The technical solution of the present invention is as follows:

[0007] A method for artificially preparing multi-scale aircraft engine environmental sediment particles comprises the following steps:

[0008] Step S1: grinding the original CMAS powder to obtain a mixture powder with uniform composition;

[0009] Step S2: Calculate the required mixture powder mass according to the powder density of the CMAS original powder and the particle size of the target sediment particles;

[0010] Step S3: Weigh the mixture powder according to the required mass of the mixture powder and press it into a sheet;

[0011] Step S4: In an air suspension furnace, a laser is used to melt the mixture powder into a spherical shape;

[0012] Step S5: Rapidly cool to room temperature to obtain target sediment particles with target particle size.

[0013] Preferably, the CMAS raw powder is artificially synthesized CMAS powder, sand, volcanic ash, dust or other natural environmental sediments.

[0014] Preferably, in step S4, the gas flow rate in the gas suspension furnace is 100-700 mm / min, and the gas is air, oxygen or nitrogen.

[0015] Preferably, the laser in step S4 is CO 2 Laser, power is 100-600W, heating temperature is 1500-3000℃, heating rate is 100-500℃ / min, and continuous holding time is 3-20s.

[0016] Preferably, during the heating and melting in step S4, the heating method of heating up, cooling down, and heating up again is repeated multiple times to remove bubbles.

[0017] Preferably, in step S5, rapid cooling is achieved by increasing the gas flow rate.

[0018] Preferably, in step S1, grinding is performed using an agate mortar, and the grinding time is not less than 15 minutes.

[0019] Preferably, the step S3 specifically includes:

[0020] The mixture powder is weighed according to the required mass of the mixture powder, and is put into a tablet pressing mold, and the tablet pressing mold is placed on a tablet pressing machine for pressurization and pressure maintenance to obtain a mixture powder tablet.

[0021] Preferably, the diameter of the die cavity of the tablet pressing mold is 1-4 mm, the pressurization pressure is 300-500 MPa, and the holding time is 3-6 min.

[0022] Preferably, the throat diameter of the nozzle connected to the air inlet valve in the furnace chamber of the gas suspension furnace is 0.5-5 mm.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention proposes an artificial preparation method for multi-scale aircraft engine environmental sediment particles. During the preparation process of the preparation method, the mixture powder is pressed into a tablet, heated and melted, and then suspended in the air without any contact with the outer wall, thereby effectively preventing the occurrence of component segregation problems and ensuring the uniformity of the sediment particles.

[0025] 2. The present invention proposes a method for artificially preparing multi-scale aircraft engine environmental sediment particles. The mixed powder tableting has the characteristics of fast heating rate and short heating time from the initial melting to the forming, which effectively prevents the problem of component volatilization.

[0026] 3. The present invention proposes a method for artificially preparing multi-scale aircraft engine environmental sediment particles. During the preparation process, different reaction atmospheres can be selected according to the different components of the CMAS original powder, thereby solving the problem that the CMAS original powder reacts with the air and thus affects the purity of the target sediment particles.

[0027] 4. The present invention proposes a method for artificially preparing multi-scale aircraft engine environmental sediment particles. By calculating the mass of CMAS original powder required for the target sediment particles and selecting nozzles with different throat diameters, target sediment particles with a diameter of 1-6 mm can be obtained.

[0028] 5. The present invention proposes a method for artificially preparing multi-scale aircraft engine environmental sediment particles, which has high preparation efficiency, and the target sediment particles prepared have uniform composition, no bubbles inside, and stable quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. The features and advantages of the present invention can be more clearly understood by referring to the drawings. The drawings are schematic and should not be understood as limiting the present invention in any way. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 The present invention is a flow chart of a method for artificially preparing multi-scale aerospace engine environmental sediment particles.

[0031] Figure 2 The present invention is a schematic diagram of air suspension for tabletting a molten mixture powder in an air suspension furnace.

[0032] Figure 3 This is a physical picture of the CMAS particles prepared in Example 1.

[0033] Figure 4 Electron probe X-ray microanalysis (EPMA) was used to determine the homogeneity and component content of the prepared samples. DETAILED DESCRIPTION

[0034] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0035] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0036] The present invention proposes a method for artificially preparing multi-scale aerospace engine environmental sediment particles, such as Figure 1 As shown, the specific steps include:

[0037] Step S1: Put the CMAS raw powder into an agate mortar and grind it thoroughly to obtain a mixture powder with uniform composition, and the grinding time is not less than 15 minutes to obtain the CMAS raw powder with uniform composition, wherein the CMAS raw powder adopts artificially synthesized CMAS powder, sand, volcanic ash, dust or other natural environmental sediments;

[0038] Step S2: Calculate the required mixture powder mass according to the powder density of the CMAS original powder and the particle size of the target sediment particles;

[0039] Step S3: After weighing, put it into a tablet pressing mold, put the tablet pressing mold on a tablet pressing machine to pressurize and hold the pressure for a period of time, the mold cavity diameter of the tablet pressing mold is 1-4 mm, the pressurization pressure is 300-500 MPa, and the holding time is 3-6 min;

[0040] Step S4: After the tablet press is depressurized, the tablet pressing mold is removed and the prepared mixture powder tablet is taken out, and the mixture powder tablet is placed in the furnace chamber of the air suspension furnace, and the air inlet valve is controlled to make the mixture powder tablet in a suspended state, and the laser is turned on, and the laser power is controlled to heat the tablet to make it molten and melt into a spherical state, such as Figure 2 As shown;

[0041] The nozzle throat diameter connected to the air inlet valve in the furnace chamber of the gas suspension furnace is 0.5-5 mm, the gas flow rate in the gas suspension furnace is 100-700 mm / min, and the gas is air, oxygen or nitrogen; the laser is CO 2 Laser, power is 100-600W, heating temperature is 1500-3000℃, heating rate is 100-500℃ / min, and continuous heat preservation time is 3-20s; when heating and melting, the heating method of heating, cooling, and then heating is repeated many times to remove bubbles;

[0042] Step S5: Turn off the laser, increase the flow rate of the air intake valve to increase the cooling rate, so that the molten ball is quickly cooled to room temperature, and then turn off the air intake valve to take out the obtained target sediment particles.

[0043] The prepared samples were tested for homogeneity and composition using EPMA. Three test points were randomly selected for each sample, and the difference in the content of each point was no more than 1%, which was defined as uniform composition. The composition of the sample with uniform composition was defined as the average value of the three test points.

[0044] Example 1

[0045] (1) Artificially synthesized CMAS powder (33CaO-9MgO-13AlO-45SiO) was selected as the original CMAS powder. 5 g of the original CMAS powder was placed in an agate mortar and ground for 20 min. In order to make the powder composition and particle size more uniform after grinding, a small amount of anhydrous ethanol can be added as a grinding medium. After grinding, the powder was placed in a sealed bag for storage for subsequent use.

[0046] (2) In order to prepare CMAS particles with diameters of 1, 2, and 3 mm, 1.48 mg, 11.84 mg, and 39.98 mg of synthetic CMAS powder were weighed according to the density of the synthetic CMAS powder. The weighed synthetic CMAS powder was placed in a tablet pressing mold with a cavity diameter of 2 mm, and the tablet pressing mold was placed on a tablet pressing machine and a radial pressure of 350 MPa was applied and maintained for 4 min.

[0047] (3) Take 1.48 mg of the pressed tablets made of the synthetic CMAS powder and put them into the furnace chamber of the air suspension furnace. The air inlet valve flow rate is set to 200, and oxygen is selected as the gas. In order to ensure that the sample does not fall into the air inlet channel after preparation, the throat diameter of the nozzle connected to the air inlet valve in the furnace chamber is selected to be 0.8 mm. Take 11.84 mg of the pressed tablets made of the synthetic CMAS powder and put them into the furnace chamber of the air suspension furnace. The air inlet valve flow rate is set to 300, and oxygen is selected as the gas. In order to ensure that the sample does not fall into the air inlet channel after preparation, the throat diameter of the nozzle connected to the air inlet valve in the furnace chamber is selected to be 1.8 mm. Take 39.98 mg of the pressed tablets made of the synthetic CMAS powder and put them into the furnace chamber of the air suspension furnace. The air inlet valve flow rate is set to 400, and oxygen is selected as the gas. In order to ensure that the sample does not fall into the air inlet channel after preparation, the throat diameter of the nozzle connected to the air inlet valve in the furnace chamber is selected to be 2.7 mm.

[0048] (4) Open CO 2 The laser power was set to 200W, the heating temperature was 1800℃, and the heating rate was 300℃ / min. The continuous holding time was 6s. In order to eliminate the residual bubbles in the sample, the "heating-cooling-heating" operation mode was repeated 5 times.

[0049] (5) Turn off CO 2 The laser cools the molten ball to room temperature quickly. 2 After the laser, increase the flow rate of the air inlet valve by 40. After the CMAS particles are completely cooled, turn off the air inlet valve and take out the obtained CMAS beads for storage. Figure 3 shown.

[0050] (6) CMAS balls were subjected to EPMA test. The test results are as follows Figure 4 shown.

[0051] Example 2

[0052] (1) Select natural volcanic ash as the original CMAS powder. Take 8g of natural volcanic ash and put it into an agate mortar for grinding for 25 minutes. In order to make the powder composition and particle size more uniform after grinding, a small amount of anhydrous ethanol can be added as a grinding medium. After grinding, the powder is placed in a sealed bag for storage for subsequent use.

[0053] (2) In order to prepare CMAS particles with diameters of 1, 2, and 3 mm, 2.41 mg, 19.24 mg, and 64.78 mg of natural volcanic ash were weighed according to the density of natural volcanic ash. The weighed natural volcanic ash was placed in a tableting mold with a cavity diameter of 1.5 mm, and the mold was placed on a tablet press and a radial pressure of 400 MPa was applied and maintained for 4 min.

[0054] (3) Take 2.41 mg of natural volcanic ash and press it into a tablet and put it into the furnace chamber of the air suspension furnace. The air intake valve flow rate is set to 300, and oxygen is selected as the gas. In order to ensure that the sample will not fall into the air intake channel after preparation, the throat diameter of the nozzle connected to the air intake valve in the furnace chamber is selected to be 0.8 mm. Take 19.24 mg of natural volcanic ash and press it into a tablet and put it into the furnace chamber of the air suspension furnace. The air intake valve flow rate is set to 400, and oxygen is selected as the gas. In order to ensure that the sample will not fall into the air intake channel after preparation, the throat diameter of the nozzle connected to the air intake valve in the furnace chamber is selected to be 1.8 mm. Take 64.78 mg of natural volcanic ash and press it into a tablet and put it into the furnace chamber of the air suspension furnace. The air intake valve flow rate is set to 500, and oxygen is selected as the gas. In order to ensure that the sample will not fall into the air intake channel after preparation, the throat diameter of the nozzle connected to the air intake valve in the furnace chamber is selected to be 2.7 mm.

[0055] (4) Open CO 2 The laser power was set to 300W, the heating temperature was 2100℃, and the heating rate was 500℃ / min. The continuous holding time was 8s. In order to eliminate the residual bubbles in the sample, the "heating-cooling-heating" operation mode was repeated 6 times.

[0056] (5) Turn off CO 2 The laser cools the molten ball to room temperature quickly. 2 After the laser, increase the flow rate of the air intake valve by 35. After the CMAS particles are completely cooled, turn off the air intake valve and take out the obtained CMAS beads for storage.

[0057] (6) The prepared CMAS beads were subjected to electron probe X-ray microanalysis (EPMA) to detect the uniformity and composition of the prepared samples.

[0058] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0060] In the present invention, the terms "first", "second", "third", "fourth" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. The term "plurality" refers to two or more, unless otherwise clearly defined.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for artificially preparing multi-scale aircraft engine environmental sediment particles, characterized in that: The following steps are involved: Step S1: grinding the original CMAS powder to obtain a mixture powder with uniform composition; Step S2: Calculate the required mixture powder mass according to the powder density of the CMAS original powder and the particle size of the target sediment particles; Step S3: Weigh the mixture powder according to the required mass of the mixture powder and press it into a sheet; Step S4: In an air suspension furnace, a laser is used to melt the mixture powder into a spherical shape; Step S5: Rapidly cool to room temperature to obtain target sediment particles with target particle size.

2. The method for artificially preparing multi-scale aircraft engine environmental sediment particles according to claim 1, characterized in that: The CMAS raw powder is artificially synthesized CMAS powder, sand, volcanic ash, dust or other natural environmental sediments.

3. The method for artificially preparing multi-scale aircraft engine environmental sediment particles according to claim 1, characterized in that: In step S4, the gas flow rate in the gas suspension furnace is 100-700 mm / min, and the gas is air, oxygen or nitrogen.

4. The method for artificially preparing multi-scale aircraft engine environmental sediment particles according to claim 1, characterized in that: In step S4, the laser is a CO2 laser with a power of 100-600W, a heating temperature of 1500-3000°C, a heating rate of 100-500°C / min, and a continuous holding time of 3-20s.

5. The method for artificially preparing multi-scale aerospace engine environmental sediment particles according to claim 1, characterized in that: During the heating and melting in step S4, the heating method of heating up, cooling down, and heating up again is repeated multiple times to remove bubbles.

6. The method for artificially preparing multi-scale aircraft engine environmental sediment particles according to claim 1, characterized in that: In step S5, the gas flow rate is increased to achieve rapid cooling.

7. The method for artificially preparing multi-scale aircraft engine environmental sediment particles according to claim 1, characterized in that: In the step S1, grinding is performed using an agate mortar, and the grinding time is not less than 15 minutes.

8. The method for artificially preparing multi-scale aircraft engine environmental sediment particles according to claim 1, characterized in that: The step S3 specifically includes: The mixture powder is weighed according to the required mass of the mixture powder, and is put into a tablet pressing mold, and the tablet pressing mold is placed on a tablet pressing machine for pressurization and pressure maintenance to obtain a mixture powder tablet.

9. The method for artificially preparing multi-scale aircraft engine environmental sediment particles according to claim 8, characterized in that: The cavity diameter of the tablet pressing mold is 1-4 mm, the pressurized pressure is 300-500 MPa, and the pressure holding time is 3-6 min.

10. The method for artificially preparing multi-scale aircraft engine environmental sediment particles according to claim 1, characterized in that: The throat diameter of the nozzle connected to the air inlet valve in the furnace chamber of the gas suspension furnace is 0.5-5 mm.

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