1. A preparation method of a nano yttria-stabilized zirconia thermal barrier coating is characterized by comprising the following steps:

step 1, preparing ZrOCl₂·8H₂O and Y (NO)₃)₃·6H₂O, mixing the solution A;

step 2, dropwise adding excessive ammonia water into the mixed solution A in the step 1 gradually and continuously stirring until Zr (OH) is generated₄And Y (OH)₃Mixed white precipitate of (2);

step 3, adding a PVA aqueous solution into the mixed white precipitate obtained in the step 2 to obtain a mixture;

step 4, placing the mixture obtained in the step 3 on a roller ball mill for ball milling to obtain ball-milled slurry;

step 5, granulating the ball-milled slurry obtained in the step 4 on a spray granulator, and removing water to obtain dry Zr (OH)₄And Y (OH)₃The spherical mixed powder of (4);

step 6, putting the spherical mixed powder obtained after granulation in the step 5 into a powder feeder, performing thermal spraying on the surface of the metal substrate in an atmospheric plasma spraying mode, and performing Zr (OH) under the condition of high-temperature flame₄And Y (OH)₃After pyrolysis, Y³⁺Incorporated into ZrO₂In the crystal lattice, a high-density nanometer yttria-stabilized zirconia thermal barrier coating is formed.

2. The method for preparing a nano-yttria-stabilized zirconia thermal barrier coating according to claim 1, wherein in the step 1, ZrOCl is added according to the volume of the mixed solution A being 1000mL₂·8H₂O and Y (NO)₃)₃·6H₂The mass fraction of O is 10-50 wt.%, Zr⁴⁺Y of (A) is³⁺The molar concentration ratio is 89: 11-97: 3.

3. the method for preparing a nano yttria-stabilized zirconia thermal barrier coating according to claim 1, wherein in the step 2, the volume concentration of ammonia water is 30-50%.

4. The method for preparing a nano yttria-stabilized zirconia thermal barrier coating according to claim 1, wherein in the step 3, the mass concentration of the PVA aqueous solution is 5-10%, and the addition amount is 100-200 mL.

5. The method for preparing a nano yttria-stabilized zirconia thermal barrier coating according to claim 1, wherein in the step 4, the rotation speed of the roller ball mill is 40-80 r/min, and the working time is 12-24 h.

6. The method for preparing a nano yttria-stabilized zirconia thermal barrier coating according to claim 1, wherein in the step 5, the parameters of the granulation are as follows: the inlet temperature of the spray granulator is 300-350 ℃, the outlet temperature is 120-150 ℃, the temperature in the cavity is 180-200 ℃, the nozzle speed is 28000-35000 r/min, and the feeding speed is 100-150 g/min.

7. The method for preparing a nano yttria-stabilized zirconia thermal barrier coating according to claim 1, wherein in step 6, parameters of the plasma spraying are as follows: current 240-280A, voltage 30-50V, primary gas Ar and N₂The flow rate is 14.0-18.0L/min, and the secondary gas N₂The flow rate is 2.0-4.0L/min, the spraying distance is 80-100 mm, the flow rate of the powder carrier gas is 3.0-5.0L/min, and the powder feeding rate is 2.0-2.5 g/min.

8. A nano yttria-stabilized zirconia thermal barrier coating, characterized by being prepared by the preparation method of any one of claims 1 to 7.

Background

In recent years, gas turbines have been rapidly developed and widely used as a new generation of energy power devices following internal combustion engines and steam engines in various fields such as energy, power generation, and ship power. With the increasing of the thermal efficiency of the gas turbine, the machine will bring more heat when working, which brings more demands and challenges to the performances of high temperature resistance, high pressure resistance, wear resistance, oxidation resistance and the like of important components in the gas turbine. The thermal barrier coating is used as a high-temperature protection technology, can effectively isolate huge heat from a protected component, and protects an internal component from being influenced by high temperature.

ZrO₂As a thermal barrier coating material, the material has the advantages of high melting point, large thermal expansion coefficient, small thermal conductivity, excellent mechanical property and the like, but ZrO₂In the process from room temperature to higher service temperature, ZrO₂A phase transition occurs, which results in ZrO during each thermal cycle₂Irreversible volume shrinkage of the coating occurs, eventually leading to peeling of the coating. And Y is₂O₃Y in (1)³⁺Due to its ionic radius and Zr⁴⁺Accordingly, the material can replace the Zr position in the crystal lattice, introduce oxygen defects to form a phonon scatterer, reduce the thermal conductivity and simultaneously prevent the crystal lattice from transforming, and avoid the problems of thermal expansion and the like during service, so that the YSZ type thermal barrier coating can be used as a thermal barrier material with development potentialOne, the first step. At present, the preparation of the YSZ coating is usually carried out by a plasma spraying method, wherein spherical YSZ powder particles are melted by high-temperature flame, and then molten or semi-molten liquid drops are blown on the surface of a workpiece by using compressed air. But due to ZrO₂The melting point of the YSZ powder is higher, the residence time in flame is shorter, and the YSZ powder cannot be completely melted, so that the prepared YSZ thermal barrier coating has the problems of low density, uneven particle distribution, poor coating adhesion and the like.

Disclosure of Invention

The invention aims to provide a nano-yttria stabilized zirconia thermal barrier coating and a preparation method thereof, which solve the problem of common ZrO₂Incomplete melting of the particles of the thermal barrier coating, low density, uneven distribution, poor adhesion of the coating and the like.

The invention is realized by adopting the following technical scheme:

a preparation method of a nanometer yttria-stabilized zirconia thermal barrier coating comprises the following steps:

step 1, preparing ZrOCl₂·8H₂O and Y (NO)₃)₃·6H₂O, mixing the solution A;

step 2, dropwise adding excessive ammonia water into the mixed solution A in the step 1 gradually and continuously stirring until Zr (OH) is generated₄And Y (OH)₃Mixed white precipitate of (2);

step 3, adding a PVA aqueous solution into the mixed white precipitate obtained in the step 2 to obtain a mixture;

step 4, placing the mixture obtained in the step 3 on a roller ball mill for ball milling to obtain ball-milled slurry;

step 5, granulating the ball-milled slurry obtained in the step 4 on a spray granulator, and removing water to obtain dry Zr (OH)₄And Y (OH)₃The spherical mixed powder of (4);

step 6, putting the spherical mixed powder obtained after granulation in the step 5 into a powder feeder, performing thermal spraying on the surface of the metal substrate in an atmospheric plasma spraying mode, and performing Zr (OH) under the condition of high-temperature flame₄And Y (OH)₃After pyrolysis, Y³⁺Incorporated into ZrO₂In the crystal lattice, a high-density nanometer yttria-stabilized zirconia thermal barrier coating is formed.

The invention is further improved in that in the step 1, ZrOCl is added according to the volume of the mixed solution A being 1000mL₂·8H₂O and Y (NO)₃)₃·6H₂The mass fraction of O is 10-50 wt.%, Zr⁴⁺Y of (A) is³⁺The molar concentration ratio is 89: 11-97: 3.

the invention has the further improvement that in the step 2, the volume concentration of the ammonia water is 30-50%.

The invention is further improved in that in the step 3, the mass concentration of the PVA aqueous solution is 5-10%, and the addition amount is 100-200 mL.

The further improvement of the invention is that in the step 4, the rotating speed of the roller ball mill is 40-80 r/min, and the working time is 12-24 h.

In a further improvement of the invention, in step 5, the granulation parameters are as follows: the inlet temperature of the spray granulator is 300-350 ℃, the outlet temperature is 120-150 ℃, the temperature in the cavity is 180-200 ℃, the nozzle speed is 28000-35000 r/min, and the feeding speed is 100-150 g/min.

The further improvement of the invention is that in step 6, the parameters of the plasma spraying are as follows: current 240-280A, voltage 30-50V, primary gas Ar and N₂The flow rate is 14.0-18.0L/min, and the secondary gas N₂The flow rate is 2.0-4.0L/min, the spraying distance is 80-100 mm, the flow rate of the powder carrier gas is 3.0-5.0L/min, and the powder feeding rate is 2.0-2.5 g/min.

A nanometer yttria-stabilized zirconia thermal barrier coating is prepared by the preparation method.

The invention has at least the following beneficial technical effects:

1. the invention provides a preparation method of a nano yttria-stabilized zirconia thermal barrier coating, which directly utilizes generated nano Zr (OH)₄And Y (OH)₃White coprecipitation is used as a precursor, and is made into mixed spherical feed through spray granulation after ball milling, so that the components of the white coprecipitation and the mixed spherical feed are uniform, and the problem of high-temperature sintering is avoidedThe crystal grains are large, the melting is easier in the spraying process, and the coating is more compact.

2. Compared with the traditional high-temperature calcination powder preparation, spray granulation and zirconia coating plasma spraying processes, the preparation method of the nano yttria-stabilized zirconia thermal barrier coating provided by the invention directly utilizes Zr (OH)₄And Y (OH)₃The spherical mixed powder of (A) is decomposed by the high-temperature action of a plasma torch as a spray coating material, and Y is³⁺Incorporated into ZrO₂Forming YSZ thermal barrier coating in the crystal lattice. The yttria-stabilized zirconia thermal barrier coating is prepared by a one-step method, the production steps are simple and convenient, the energy is saved, and the cost is low;

3. compared with the traditional thermal barrier coating process, the nano-grade zirconia powder is used as the raw material, the relative density of the obtained coating is increased from 62.3% to 84.5%, and the bonding force between the coating and a substrate is increased from 35.2N to 52.4N. The feed has more complete melting degree, high density and stronger adhesive force with the substrate, and solves the problem of common ZrO₂Incomplete melting of the particles of the thermal barrier coating, low density, uneven distribution, poor adhesion of the coating and the like.

Drawings

FIG. 1 shows Zr (OH) according to the present invention₄And Y (OH)₃SEM picture of the ball feedstock;

FIG. 2 is an XRD pattern of a yttria-stabilized zirconia thermal barrier coating prepared in accordance with the present invention;

FIG. 3 is an SEM image of a yttria-stabilized zirconia thermal barrier coating prepared in accordance with the present invention;

FIG. 4 is a graph of the mechanical properties of a yttria-stabilized zirconia thermal barrier coating prepared in accordance with the present invention, wherein FIG. 4(a) is a graph of relative density of the coating and FIG. 4(b) is a graph of bonding force.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

The invention provides a preparation method of a nano yttria-stabilized zirconia thermal barrier coating, which is implemented by the following steps:

step 1, preparing ZrOCl according to a certain proportion₂·8H₂O/Y(NO₃)₃·6H₂O, mixing the solution; the volume of the mixed solution is 1000mL, ZrOCl₂·8H₂O and Y (NO)₃)₃·6H₂The mass fraction of O is 10-50 wt.%, Zr⁴⁺Y of (A) is³⁺The molar concentration ratio is 89: 11-97: 3.

step 2, dropwise adding excessive ammonia water into the mixed solution in the step 1 step by step and continuously stirring until Zr (OH) is generated₄And Y (OH)₃Mixed white precipitate of (2); wherein the concentration of the ammonia water is 30-50%.

Step 3, adding a certain amount of PVA aqueous solution into the solution in the step 2; the concentration of PVA is 5-10%, and the addition amount is 100-200 mL.

Step 4, placing the mixture obtained in the step 3 on a roller ball mill for ball milling; the rotating speed of the roller ball mill is 40-80 r/min, and the working time is 12-24 h.

Step 5, granulating the ball-milled slurry obtained in the step 4 on a spray granulator, and removing water to obtain dry Zr (OH)₄And Y (OH)₃The spherical mixed powder of (4); wherein the granulation parameters are as follows: the inlet temperature of the spray granulator is 300-350 ℃, the outlet temperature is 120-150 ℃, the temperature in the cavity is 180-200 ℃, the nozzle speed is 28000-35000 r/min, and the feeding speed is 100-150 g/min;

step 6, putting the spherical powder obtained after granulation in the step 5 into a powder feeder, performing thermal spraying on the surface of the metal substrate in an atmospheric plasma spraying mode, and performing Zr (OH) under the condition of high-temperature flame₄And Y (OH)₃After pyrolysis, Y³⁺Incorporated into ZrO₂In the crystal lattice, a high-density nanometer yttria-stabilized zirconia (YSZ) thermal barrier coating is formed. Wherein the parameters of plasma spraying are as follows: current 240-280A, voltage 30-50V, primary gas (Ar + N)₂) A flow rate of 14.0 to 18.0L/min, and a secondary gas (N)₂) The flow rate is 2.0-4.0L/min, the spraying distance is 80-100 mm, the flow rate of the powder carrier gas is 3.0-5.0L/min, and the powder feeding rate is 2.0-2.5 g/min.

Example 1

Step 1, preparing ZrOCl with a certain proportion₂·8H₂O/Y(NO₃)₃·6H₂O mixed solution: preparing 1000mL of mixed solution ZrOCl₂·8H₂O/Y(NO₃)₃·6H₂Mass fraction of O10 wt.%, Zr⁴⁺Y of (A) is³⁺The molar concentration ratio is 89: 11.

step 2, dropwise adding excessive ammonia water into the mixed solution in the step 1 and continuously stirring until Zr (OH) is generated₄And Y (OH)₃Mixed white precipitate of (2): wherein the concentration of ammonia is 30 wt.%.

Step 3, adding a certain amount of PVA aqueous solution into the solution in the step 2; the PVA concentration was 5% and the amount added was 200 mL.

Step 4, placing the mixture obtained in the step 3 on a roller ball mill for ball milling; the rotating speed of the roller ball mill is 40r/min, and the working time is 12 h.

Step 5, granulating the ball-milled slurry obtained in the step 4 on a spray granulator, and removing water to obtain dry Zr (OH)₄And Y (OH)₃The spherical mixed powder of (4); wherein the granulation parameters are as follows: the inlet temperature of the spray granulator is 350 ℃, the outlet temperature is 150 ℃, the temperature in the cavity is 200 ℃, the nozzle speed is 28000r/min, and the feeding speed is 100 g/min;

step 6, putting the spherical powder obtained after granulation in the step 5 into a powder feeder, performing thermal spraying on the surface of the metal substrate in an atmospheric plasma spraying mode, and performing Zr (OH) under the condition of high-temperature flame₄And Y (OH)₃After pyrolysis, Y³⁺Incorporated into ZrO₂In the crystal latticeAnd forming the high-density nano yttria-stabilized zirconia (YSZ) thermal barrier coating. Wherein the parameters of plasma spraying are as follows: current 240A, voltage 50V, primary gas (Ar + N)₂) Flow rate 14.0L/min, secondary gas (N)₂) The flow rate is 2.0L/min, the spraying distance is 80mm, the flow rate of the powder carrier gas is 3.0L/min, and the powder feeding rate is 2.0 g/min.

Example 2

Step 1, preparing ZrOCl with a certain proportion₂·8H₂O/Y(NO₃)₃·6H₂O mixed solution: preparing 1000mL of mixed solution ZrOCl₂·8H₂O/Y(NO₃)₃·6H₂Mass fraction of O30 wt.%, Zr⁴⁺Y of (A) is³⁺The molar concentration ratio is 97: 3.

step 2, dropwise adding excessive ammonia water into the mixed solution in the step 1 step by step and continuously stirring until Zr (OH) is generated₄And Y (OH)₃Mixed white precipitate of (2); wherein the concentration of ammonia water is 50%.

Step 3, adding a certain amount of PVA aqueous solution into the solution in the step 2; the PVA concentration was 10% and the amount added was 100 mL.

Step 4, placing the mixture obtained in the step 3 on a roller ball mill for ball milling; the rotating speed of the roller ball mill is 80r/min, and the working time is 12 h.

Step 5, granulating the ball-milled slurry obtained in the step 4 on a spray granulator, and removing water to obtain dry Zr (OH)₄And Y (OH)₃The spherical mixed powder of (4); wherein the granulation parameters are as follows: the inlet temperature of the spray granulator is 300 ℃, the outlet temperature is 120 ℃, the temperature in the cavity is 180 ℃, the nozzle speed is 35000r/min, and the feeding speed is 150 g/min;

step 6, putting the spherical powder obtained after granulation in the step 5 into a powder feeder, performing thermal spraying on the surface of the metal substrate in an atmospheric plasma spraying mode, and performing Zr (OH) under the condition of high-temperature flame₄And Y (OH)₃After pyrolysis, Y³⁺Incorporated into ZrO₂In the crystal lattice, a high-density nanometer yttria-stabilized zirconia (YSZ) thermal barrier coating is formed. Wherein the parameters of plasma spraying are as follows: current 280A, voltage 30VPrimary gas (Ar + N)₂) Flow rate 18.0L/min, secondary gas (N)₂) The flow rate is 4.0L/min, the spraying distance is 100mm, the flow rate of the powder carrier gas is 5.0L/min, and the powder feeding rate is 2.5 g/min.

Example 3

Step 1, preparing ZrOCl with a certain proportion₂·8H₂O/Y(NO₃)₃·6H₂O mixed solution: preparing 1000mL of mixed solution ZrOCl₂·8H₂O/Y(NO₃)₃·6H₂Mass fraction of O40 wt.%, Zr⁴⁺Y of (A) is³⁺The molar concentration ratio is 95: 5.

step 2, dropwise adding excessive ammonia water into the mixed solution in the step 1 step by step and continuously stirring until Zr (OH) is generated₄And Y (OH)₃Mixed white precipitate of (2); wherein the concentration of ammonia water is 50%.

Step 3, adding a certain amount of PVA aqueous solution into the solution in the step 2; the PVA concentration was 10% and the amount added was 150 mL.

Step 4, placing the mixture obtained in the step 3 on a roller ball mill for ball milling; the rotating speed of the roller ball mill is 80r/min, and the working time is 12 h.

Step 5, granulating the ball-milled slurry obtained in the step 4 on a spray granulator, and removing water to obtain dry Zr (OH)₄And Y (OH)₃The spherical mixed powder of (4); wherein the granulation parameters are as follows: the inlet temperature of the spray granulator is 320 ℃, the outlet temperature is 130 ℃, the temperature in the cavity is 190 ℃, the nozzle speed is 30000r/min, and the feeding speed is 120 g/min;

step 6, putting the spherical powder obtained after granulation in the step 5 into a powder feeder, performing thermal spraying on the surface of the metal substrate in an atmospheric plasma spraying mode, and performing Zr (OH) under the condition of high-temperature flame₄And Y (OH)₃After pyrolysis, Y³⁺Incorporated into ZrO₂In the crystal lattice, a high-density nanometer yttria-stabilized zirconia (YSZ) thermal barrier coating is formed. Wherein the parameters of plasma spraying are as follows: current 260A, Voltage 40V, Primary gas (Ar + N)₂) Flow rate of 16.0L/min, secondary gas (N)₂) Flow rate of 3.0L/min, spraying distance of 90mm, powder carrier gasThe flow rate is 40L/min, and the powder feeding rate is 2.3 g/min.

Example 4

Step 1, preparing ZrOCl with a certain proportion₂·8H₂O/Y(NO₃)₃·6H₂O mixed solution: preparing 1000mL of mixed solution ZrOCl₂·8H₂O/Y(NO₃)₃·6H₂Mass fraction of O40 wt.%, Zr⁴⁺Y of (A) is³⁺The molar concentration ratio is 95: 5.

step 2, dropwise adding excessive ammonia water into the mixed solution in the step 1 step by step and continuously stirring until Zr (OH) is generated₄And Y (OH)₃Mixed white precipitate of (2); wherein the concentration of the ammonia water is 40 percent.

Step 3, adding a certain amount of PVA aqueous solution into the solution in the step 2; the PVA concentration was 5% and the amount added was 150 mL.

Step 4, placing the mixture obtained in the step 3 on a roller ball mill for ball milling; the rotating speed of the roller ball mill is 60r/min, and the working time is 18 h.

Step 5, granulating the ball-milled slurry obtained in the step 4 on a spray granulator, and removing water to obtain dry Zr (OH)₄And Y (OH)₃The spherical mixed powder of (4); wherein the granulation parameters are as follows: the inlet temperature of the spray granulator is 330 ℃, the outlet temperature is 130 ℃, the temperature in the cavity is 180 ℃, the nozzle speed is 32000r/min, and the feeding speed is 120 g/min;

step 6, putting the spherical powder obtained after granulation in the step 5 into a powder feeder, performing thermal spraying on the surface of the metal substrate in an atmospheric plasma spraying mode, and performing Zr (OH) under the condition of high-temperature flame₄And Y (OH)₃After pyrolysis, Y³⁺Incorporated into ZrO₂In the crystal lattice, a high-density nanometer yttria-stabilized zirconia (YSZ) thermal barrier coating is formed. Wherein the parameters of plasma spraying are as follows: current 280A, Voltage 40V, Primary gas (Ar + N)₂) Flow rate 18.0L/min, secondary gas (N)₂) The flow rate is 4.0L/min, the spraying distance is 80mm, the flow rate of the powder carrier gas is 3.5L/min, and the powder feeding rate is 2.3 g/min.

The high-density nano oxygen prepared by the method of the inventionYttrium stabilized zirconia thermal barrier coating Zr (OH)₄And Y (OH)₃As shown in fig. 1, it can be seen that the spherical feed is composed of countless fine nanoparticles without fine particles, which is favorable for melting in plasma high temperature flame.

The invention directly utilizes Zr (OH)₄And Y (OH)₃The spherical mixed powder is used as a spray coating, is decomposed under the high-temperature action of a plasma spray gun, and is used for preparing the yttria-stabilized zirconia thermal barrier coating by a one-step method, so that the production steps are simple and convenient, the energy is saved, and the cost is lower.

XRD and SEM images of the yttria zirconia thermal barrier coating obtained by the method of the invention; as shown in FIGS. 2 and 3, it can be seen that only tetragonal ZrO was present in the coating obtained after spraying₂Description of Zr (OH) after passing through the high-temperature lance₄And Y (OH)₃Are all completely decomposed, and Y³⁺Is dissolved in ZrO₂In the crystal lattice of (1), stabilized ZrO₂The function of the crystal form; in addition, the prepared coating has high melting degree, very compact coating, almost no obvious air holes and very uniform distribution, which is beneficial to improving the service life of the thermal barrier coating and the direct bonding strength of the coating and the substrate.

FIG. 4 is a graph of the mechanical properties of a yttria-stabilized zirconia thermal barrier coating prepared in accordance with the present invention. It can be seen that the YSZ coating prepared by the present invention, whether it is denser or has higher bonding strength to the substrate than commercial YSZ coatings. The relative density of the coating obtained by the invention is increased from 62.3% to 84.5%, and the bonding force between the coating and the substrate is increased from 35.2N to 52.4N.

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.