CN116445848A - Preparation method of ceramic coating with longitudinal crack growth capability - Google Patents

Abstract

A preparation method of a ceramic coating with longitudinal crack growth capability. Which comprises MK resin solution preparation; preparing a metal bonding layer; preparing a first ceramic coating; preparing and curing a first MK resin layer; preparing a second ceramic coating; and preparing and curing the second MK resin layer. The invention has low cost and simple preparation process, only needs a small amount of absolute ethyl alcohol and MK resin raw materials, and can prepare the ceramic coating with longitudinal crack growth capability by respectively spraying a discontinuous MK resin layer on the inner part and the surface of the plasma spraying ceramic coating by using the reusable porous mask. On the basis of ensuring that the bonding strength of the ceramic coating is not obviously reduced, the longitudinal micro-cracking of the discontinuous MK resin layer in the thermal cycle process can consume thermal cycle energy, release thermal cycle internal stress and reduce crack expansion driving force at the interface of part of the ceramic coating/bonding layer, thereby obviously prolonging the thermal cycle life of the ceramic coating.

Description

Preparation method of ceramic coating with longitudinal crack growth ability

technical field

The invention belongs to the technical field of ceramic coating structure design and optimization, and in particular relates to a preparation method of a ceramic coating capable of growing longitudinal cracks.

Background technique

At present, ceramic coatings (thermal barrier coatings, high-temperature sealing coatings, etc.) prepared by plasma spraying (APS) technology have been widely used in the hot end parts of aero-engines. However, due to the harsh service environment, ceramic coatings are prone to spalling failures. There are two main mechanical causes that lead to the peeling off of APS conventional ceramic coatings, one of which is the growth stress formed by the volume growth of thermally grown oxides. The second cause is the interfacial mismatch stress due to the mismatch of thermal expansion coefficients between the superalloy substrate, bonding layer, ceramic coating, and thermally grown oxide (TGO) layer. Therefore, one of the effective ways to improve the service life of ceramic coatings is to control the driving force of crack growth, that is, to release the growth stress of the growing TGO layer and the thermal mismatch stress at the ceramic coating/TGO interface during the working process of the ceramic coating. .

Early researchers used the electron beam physical vapor deposition (EB-PVD) method to prepare ceramic coatings with a "columnar" structure, and the internal stress can be effectively released through numerous "column" micro-cracks, so the EB-PVD method prepared The ceramic coating has good performance, but the cost of EB-PVD is expensive, and the coating deposition efficiency is very low. Plasma-enhanced chemical vapor deposition technology (PE-CVD), laser chemical vapor deposition technology (L-CVD), plasma physical vapor deposition technology (PS-PVD) and low-pressure plasma spraying thin coating technology (LPPS-TF) were successively developed in the later stage Ceramic coatings with "columnar" or similar "columnar" structures can be prepared, which improves the life of ceramic coatings to varying degrees. However, the above methods still face the challenges of demanding raw materials, low deposition efficiency, expensive equipment or The coating forming process is complex and other problems.

Another way to release the internal stress of ceramic coatings is micro-crack technology. At first, scholars at home and abroad can prepare ceramic coatings with longitudinal cracks by using suspension plasma spraying technology (SPS) and solution precursor plasma spraying technology (SPPS). , these longitudinal cracks are similar to the columnar grain gaps in EB-PVD coatings, which have the function of internal stress release, thereby improving the strain tolerance and life of ceramic coatings. However, the coating process of SPS and SPPS is complicated, and the volatilization of the solvent in the suspension or solution precursor will absorb a lot of heat, and the spraying distance is greatly reduced compared with the plasma spraying technology, resulting in a decrease in the stability and controllability of the coating preparation process. In 2013 and 2014, Lisa Pin et al. and Lu Zhe et al. successively proposed the method of using sol-gel (Sol-Gel) + high temperature heat treatment to generate network cracks and surface concentrated heating to generate longitudinal cracks, which prolong the ceramic coating to varying degrees. layer life. However, the shape of cracks produced by Sol-Gel+ high temperature treatment is irregular, and the density is uncontrollable. Some cracked areas are difficult to fill with plasma sprayed coatings, which makes the service life of thermal barrier coatings with this structure unstable. The method of concentrated surface heating to generate longitudinal cracks has low density and uneven distribution, and is prone to continuous growth of transverse cracks, which has limited effect on improving coating performance. In 2018, ZengJinyan et al. used APS combined with dry ice blasting technology to implant microcracks in the ceramic coating. The vertical microcracks in the coating not only reduced the thermal stress, but also improved the strain tolerance of the ceramic coating, thereby improving the ceramic coating. layer lifetime. However, this method cannot control the formation of transverse microcracks, and lamellar exfoliation failure caused by continuous growth of transverse cracks is prone to occur.

The above studies all use a certain technology or method to optimize the micromorphology or microstructure of the ceramic coating, by releasing the growing stress of the TGO layer and the thermal mismatch at the interface of the ceramic surface layer/TGO layer during the working process. stress to improve the thermal cycle cracking resistance of ceramic coatings, but the above methods still face problems such as high preparation cost, low production efficiency, high technical difficulty, and poor effect.

Contents of the invention

In order to solve the above problems, the object of the present invention is to provide a method for preparing a ceramic coating capable of growing longitudinal cracks.

In order to achieve the above object, the ceramic coating preparation method provided by the present invention has the ability to grow longitudinal cracks and includes the following steps in order:

1) Preparation of MK resin solution: using a magnetic stirrer to stir absolute ethanol as a solvent and MK resin as a solute to prepare a resin solution;

2) Preparation of metal bonding layer: CoCrAlY powder is sprayed on the surface of nickel-based alloy substrate by plasma spraying technology to prepare a metal bonding layer;

3) Preparation of the first layer of ceramic coating: use plasma spraying technology to spray YSZ powder (brand AI-1075) on the surface of the above-mentioned metal bonding layer to prepare the first layer of ceramic coating;

4) Preparation of the first layer of MK resin layer: using a porous mask and a spray gun to spray the MK resin solution prepared in step 1) on the surface of the first layer of ceramic coating to prepare the first layer of MK resin with the function of longitudinal crack growth layer;

5) curing of the first MK resin layer: placing the nickel-based alloy substrate with the MK resin layer prepared in step 4) in a high-temperature electric furnace for heating and curing;

6) Preparation of the second layer of ceramic coating: repeat step 3) to prepare a second layer of ceramic coating on the surface of the first layer of MK resin layer;

7) preparation of the second layer of MK resin layer: repeat step 4), prepare the second layer of MK resin layer on the surface of the second layer of ceramic coating;

8) The second layer of MK resin layer is cured: repeat step 5), thus making the ceramic coating capable of growing longitudinal cracks.

In step 1), the weight ratio of the absolute ethanol to the MK resin is 30-40:5-7; the rotating speed of the magnetic stirrer is 700-800r/min, the stirring time is 14-16h, and the stirring temperature is room temperature.

In step 2), the plasma spraying voltage is 40-41V, the current is 780-800A, the powder feeding rate is 30-35g/min, the spraying distance is 100-120mm, and the thickness of the metal bonding layer is 100-150μm .

In step 3) and step 6), the voltage of the plasma spraying is 40.5-41.5V, the current is 790-810A, the powder feeding rate is 35-40g/min, the spraying distance is 100-120mm, the first layer of ceramic coating The thickness of the layer is 200 to 250 μm.

In step 4) and step 7), the pressure of the spraying gun is 0.5-0.6 MPa, the spraying distance is 150-200 mm, and the amount of spraying MK resin solution is 8-10 ml/506 mm ² .

In step 5) and step 8), the heating and curing temperature of the high-temperature electric furnace is 600-800° C., and the curing time is 25-35 minutes.

The preparation method of the ceramic coating provided by the present invention with the ability to grow longitudinal cracks has the following advantages:

(1) The cost is low, and the preparation process is relatively simple. Only a small amount of absolute ethanol and MK resin raw materials are used to spray a layer of discontinuous ceramic coating on the inside and surface of the plasma sprayed ceramic coating using a reusable porous mask. MK resin layer, a ceramic coating with longitudinal crack growth ability can be prepared.

(2) The discontinuous MK resin prepared based on the porous mask can prevent the continuous growth of transverse cracks. On the basis of ensuring that the bonding strength of the ceramic coating does not decrease significantly, the longitudinal microstructure of the discontinuous MK resin layer during the thermal cycle Cracking can consume thermal cycle energy, release thermal cycle internal stress, and reduce crack propagation driving force at part of the ceramic coating/bonding layer interface, thereby significantly improving the thermal cycle life of the ceramic coating.

Description of drawings

Figure 1 is the micrograph of the discontinuous MK resin layer prepared by spraying gun, where the magnifications of (a) and (b) are 200 and 20 respectively.

Fig. 2 is the cross-sectional morphology of the ceramic coating with longitudinal crack growth ability provided by the present invention before thermal cycle.

Fig. 3 shows the cross-sectional morphology of the ceramic coating with longitudinal crack growth ability provided by the present invention after 50 thermal cycles (one thermal cycle process is 1100 ° C for 15 minutes, compressed air cooling for 15 minutes).

Figure 4 shows the cross-sectional morphology of the ceramic coating with longitudinal crack growth ability provided by the present invention after 150 thermal cycles (one thermal cycle process is 1100 ° C for 15 minutes, compressed air cooling for 15 minutes).

Detailed ways

Embodiments of the present invention are described in detail below, and the embodiments are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

Example 1:

The method for preparing a ceramic coating with the ability to grow longitudinal cracks provided in this embodiment includes the following steps in order:

1) Preparation of MK resin solution: Utilize magnetic stirrer to stir dehydrated alcohol as solvent and MK resin as solute to be prepared into MK resin solution, the weight ratio of dehydrated alcohol and MK resin is 30: 5, the magnetic stirrer The rotating speed is 700r/min, the stirring time is 14h, and the stirring temperature is room temperature;

2) Preparation of metal bonding layer: use plasma spraying technology to spray CoCrAlY powder (grade CO110) on the surface of nickel-based alloy substrate to prepare a metal bonding layer. The voltage of plasma spraying is 40V, the current is 780A, and the powder feeding rate is The spraying distance is 30g/min, the spraying distance is 100mm, and the thickness of the metal bonding layer is 100μm;

3) Preparation of the first layer of ceramic coating: use plasma spraying technology to spray YSZ powder (brand name AI-1075) on the surface of the above metal bonding layer to prepare the first layer of ceramic coating, and the voltage of plasma spraying is 40.5V , the current is 790A, the powder feeding rate is 35g/min, the spraying distance is 100mm, and the thickness of the first layer of ceramic coating is 200μm;

4) Preparation of the first layer of MK resin layer: using a porous mask and a spray gun to spray the MK resin solution prepared in step 1) on the surface of the first layer of ceramic coating to prepare the first layer of MK resin with the function of longitudinal crack growth layer, the pressure of the spraying gun is 0.5MPa, the spraying distance is 150mm, and the amount of spraying MK resin solution is 8ml/506mm ² ;

5) The first layer of MK resin layer is cured: the nickel-based alloy substrate with the MK resin layer prepared in step 4) is placed in a high-temperature electric furnace for heating and curing, the curing temperature is 600°C, and the curing time is 25 minutes;

6) Preparation of the second layer of ceramic coating: repeat step 3), prepare the second layer of ceramic coating on the surface of the first layer of MK resin, the voltage of plasma spraying is 40.5V, the current is 790A, and the powder feeding rate is 35g/ min, the spraying distance is 100mm, and the thickness of the second layer of ceramic coating is 200μm;

7) preparation of the second layer of MK resin layer: repeat step 4), prepare the second layer of MK resin layer on the surface of the second layer of ceramic coating, the pressure of the spraying gun is 0.5MPa, and the spraying distance is 150mm, spraying the MK resin solution The dosage is 8ml/506mm ² ;

8) Curing of the second MK resin layer: Repeat step 5), the curing temperature is 600° C., and the curing time is 25 minutes, thereby preparing the ceramic coating with the ability to grow longitudinal cracks.

Example 2:

The method for preparing a ceramic coating with the ability to grow longitudinal cracks provided in this embodiment includes the following steps in order:

1) Preparation of MK resin solution: Utilize magnetic stirrer to stir dehydrated alcohol as solvent and MK resin as solute and prepare MK resin solution, the weight ratio of dehydrated alcohol and MK resin is 35: 6, the magnetic stirrer The rotating speed is 750r/min, the stirring time is 15h, and the stirring temperature is room temperature;

2) Preparation of metal bonding layer: use plasma spraying technology to spray CoCrAlY powder (brand CO110) on the surface of nickel-based alloy substrate to prepare a metal bonding layer. The voltage of plasma spraying is 40.5V, the current is 790A, and the powder feeding The speed is 32g/min, the spraying distance is 110mm, and the thickness of the metal bonding layer is 120μm. ;

3) Preparation of the first layer of ceramic coating: use plasma spraying technology to spray YSZ powder (grade AI-1075) on the surface of the above-mentioned metal bonding layer to prepare the first layer of ceramic coating, the voltage of plasma spraying is 41V, The current is 800A, the powder feeding rate is 37g/min, the spraying distance is 110mm, and the thickness of the first layer of ceramic coating is 220μm;

4) Preparation of the first layer of MK resin layer: using a porous mask and a spray gun to spray the MK resin solution prepared in step 1) on the surface of the first layer of ceramic coating to prepare the first layer of MK resin with the function of longitudinal crack growth layer, the pressure of the spraying gun is 0.55MPa, the spraying distance is 170mm, and the amount of spraying MK resin solution is 9ml/506mm ² ;

5) The first layer of MK resin layer is cured: the nickel-based alloy substrate with the first layer of MK resin layer prepared in step 4) is placed in a high-temperature electric furnace for heating and curing, the curing temperature is 700°C, and the curing time is 30 minutes;

6) Preparation of the second layer of ceramic coating: repeat step 3), prepare the second layer of ceramic coating on the surface of the first layer of MK resin layer, the voltage of plasma spraying is 41V, the current is 800A, and the powder feeding rate is 37g/ min, the spraying distance is 110mm, and the thickness of the second layer of ceramic coating is 220μm;

7) preparation of the second layer of MK resin layer: repeat step 4), and prepare the second layer of MK resin layer on the surface of the second layer of ceramic coating, the pressure of the spraying gun is 0.55MPa, and the spraying distance is 170mm, spraying the MK resin The amount of solution is 9ml/506mm ² ;

8) Curing of the second MK resin layer: Repeat step 5), the curing temperature is 700° C., and the curing time is 30 minutes, thereby preparing the ceramic coating with the ability to grow longitudinal cracks.

Example 3:

The method for preparing a ceramic coating with the ability to grow longitudinal cracks provided in this embodiment includes the following steps in order:

1) Preparation of MK resin solution: Utilize magnetic stirrer to stir dehydrated alcohol as solvent and MK resin as solute and prepare MK resin solution, the weight ratio of dehydrated alcohol and MK resin is 40: 7, the magnetic stirrer The rotating speed is 800r/min, the stirring time is 16h, and the stirring temperature is room temperature;

2) Preparation of metal bonding layer: use plasma spraying technology to spray (CoCrAlY powder, grade CO110) on the surface of nickel-based alloy substrate to prepare a metal bonding layer. The voltage of plasma spraying is 41V, the current is 800A, and the powder feeding rate is The spraying distance is 35g/min, the spraying distance is 120mm, and the thickness of the metal bonding layer is 150μm. ;

3) Preparation of the first layer of ceramic coating: use plasma spraying technology to spray YSZ powder (brand name AI-1075) on the surface of the above metal bonding layer to prepare the first layer of ceramic coating, and the voltage of plasma spraying is 41.5V , the current is 810A, the powder feeding rate is 40g/min, the spraying distance is 120mm, and the thickness of the first layer of ceramic coating is 250μm;

4) Preparation of the first layer of MK resin layer: using a porous mask and a spray gun to spray the MK resin solution prepared in step 1) on the surface of the first layer of ceramic coating to prepare the first layer of MK resin with the function of longitudinal crack growth layer, the pressure of the spraying gun is 0.6MPa, the spraying distance is 200mm, and the amount of spraying MK resin solution is 10ml/506mm ² ;

5) The first layer of MK resin layer is cured: the nickel-based alloy substrate with the first layer of MK resin layer prepared in step 4) is placed in a high-temperature electric furnace for heating and curing, the curing temperature is 800 ° C, and the curing time is 35 minutes;

6) Preparation of the second layer of ceramic coating: repeat step 3), prepare the second layer of ceramic coating on the surface of the first layer of MK resin layer, the voltage of plasma spraying is 41.5V, the current is 810A, and the powder feeding rate is 40g /min, the spraying distance is 120mm, and the thickness of the second layer of ceramic coating is 250μm;

7) preparation of the second layer of MK resin layer: repeat step 4), prepare the second layer of MK resin layer on the surface of the second layer of ceramic coating, the pressure of the spraying gun is 0.6MPa, and the spraying distance is 200mm, spraying the MK resin solution The dosage is 10ml/506mm ² ;

8) Curing of the second MK resin layer: Step 5) was repeated, the curing temperature was 800° C., and the curing time was 35 minutes, thereby producing the ceramic coating capable of growing longitudinal cracks.

Figure 1 is the micrograph of the discontinuous MK resin layer prepared by spraying gun, where the magnifications of (a) and (b) are 200 and 20 respectively. It can be seen from Figure 1 that the MK resin layer prepared based on the shielding effect of the circular hole mask presents a discontinuous arrangement on the ceramic coating.

Fig. 2 is the cross-sectional morphology of the ceramic coating with longitudinal crack growth ability provided by the present invention before thermal cycle. It can be seen from Figure 2 that after adding two discontinuous MK resin layers, there is no obvious interface in the cross-sectional morphology of the new ceramic coating, and the combination between the ceramic coating and the discontinuous MK resin layer is good, and the new ceramic coating The layers were free of cracking prior to thermal cycling.

Figure 3 and Figure 4 respectively show the cross-sectional morphology of the ceramic coating with longitudinal crack growth ability provided by the present invention after 50 and 150 thermal cycles. It can be seen from Figure 3 that after 50 thermal cycles of the new ceramic coating, obvious longitudinal cracks appeared in the ceramic coating, and there were almost no obvious transverse cracks, and the bonding between the ceramic coating and the metal bonding layer remained intact. good. It can be seen from Figure 4 that with the continuous increase of the number of thermal cycles, after 150 thermal cycles of the new ceramic coating, the ceramic coating has obvious sintering phenomenon, but the ceramic coating is still dominated by longitudinal cracks. There are only a few transverse cracks, and only slight cracks appear at the interface between the ceramic coating and the metal bonding layer.

The reason why the ceramic coating with longitudinal crack growth ability provided by the present invention has a better thermal cycle life is that the non-continuous MK resin prepared based on the porous mask can prevent the continuous growth of transverse cracks, thereby ensuring the new ceramic coating. The bonding strength of the layers does not decrease significantly; on the other hand, through the longitudinal micro-cracks of the discontinuous MK resin layer during the thermal cycle, the thermal cycle energy can be consumed, the internal stress of the thermal cycle can be released, and part of the ceramic coating/bonding layer interface can be reduced. The driving force for crack growth at this point can significantly improve the thermal cycle life of the new ceramic coating.

Claims (6)

1. A preparation method of a ceramic coating with longitudinal crack growth capability is characterized by comprising the following steps: the preparation method of the ceramic coating comprises the following steps in sequence:

1) MK resin solution preparation: stirring absolute ethanol as a solvent and MK resin as a solute by using a magnetic stirrer to prepare a resin solution;

2) Preparing a metal bonding layer: spraying CoCrAlY powder on the surface of a nickel-based alloy matrix by using a plasma spraying technology to prepare a metal bonding layer;

3) Preparing a first ceramic coating: spraying YSZ powder on the surface of the metal bonding layer by using a plasma spraying technology to prepare a first ceramic coating;

4) Preparing a first MK resin layer, namely spraying the MK resin solution prepared in the step 1) on the surface of the first ceramic coating layer by using a porous mask plate and a spraying gun to prepare the first MK resin layer with a longitudinal crack growth function;

5) Curing the first MK resin layer: placing the nickel-based alloy matrix with the MK resin layer prepared in the step 4) into a high-temperature electric furnace for heating and curing;

6) Preparing a second ceramic coating: repeating the step 3), and preparing a second ceramic coating on the surface of the first MK resin layer;

7) Preparing a second MK resin layer, namely repeating the step 4), and preparing the second MK resin layer on the surface of the second ceramic coating layer;

8) And (3) curing the second MK resin layer: repeating step 5), thereby producing the ceramic coating with longitudinal crack growth capability.

2. The method for producing a ceramic coating with longitudinal crack growth ability according to claim 1, characterized in that: in the step 1), the weight ratio of the absolute ethyl alcohol to the MK resin is 30-40:5-7; the rotating speed of the magnetic stirrer is 700-800 r/min, the stirring time is 14-16 h, and the stirring temperature is room temperature.

3. The method for producing a ceramic coating with longitudinal crack growth ability according to claim 1, characterized in that: in the step 2), the voltage of the plasma spraying is 40-41V, the current is 780-800A, the powder feeding rate is 30-35 g/min, the spraying distance is 100-120 mm, and the thickness of the metal bonding layer is 100-150 mu m.

4. The method for producing a ceramic coating with longitudinal crack growth ability according to claim 1, characterized in that: in the step 3) and the step 6), the voltage of the plasma spraying is 40.5-41.5V, the current is 790-810A, the powder feeding rate is 35-40 g/min, the spraying distance is 100-120 mm, and the thickness of the first ceramic coating is 200-250 mu m.

5. The method for producing a ceramic coating with longitudinal crack growth ability according to claim 1, characterized in that: in the step 4) and the step 7), the pressure of the spraying gun is 0.5-0.6 MPa, the spraying distance is 150-200 mm, and the using amount of the sprayed MK resin solution is 8-10 ml/506mm ² 。

6. The method for producing a ceramic coating with longitudinal crack growth ability according to claim 1, characterized in that: in the step 5) and the step 8), the heating curing temperature of the high-temperature electric furnace is 600-800 ℃ and the curing time is 25-35 min.