A method for preparing a chemical vapor deposition dysprosium hafnate ceramic coating

Abstract

The application is a preparation method of a chemical vapor deposition dysprosium hafnium oxide ceramic coating, which uses Dy and Hf metal particles and related process gas as raw materials, uses chemical vapor deposition technology, and controls the heating temperature of a vacuum chamber of a chemical vapor deposition device, vacuum degree, process gas type and flow, deposition time and other factors to first co-deposit and prepare Dy2O3 and HfO2 mixed oxides on the surface of a nickel-based high-temperature alloy, and then in-situ synthesize a Dy2Hf2O7 ceramic coating with a fluorite structure at high temperature. The ceramic coating has the advantages of stable high-temperature phase structure, low thermal conductivity, sintering resistance, molten salt corrosion resistance and excellent strain tolerance, is suitable for use in high-temperature flame service working conditions above 1300 DEG C, and can improve the heat insulation effect of the thermal barrier coating of the turbine blade of an aero-engine.

Description

TECHNICAL FIELD

[0001] The application is a preparation method of chemical vapor deposition dysprosium hafnate ceramic coating, belonging to high-temperature protective coating manufacturing technology. BACKGROUND

[0002] With the development of modern aviation gas turbine engine towards high thrust-to-weight ratio, high efficiency, low fuel consumption and long service life, the service temperature of the hot end component is also higher and higher, and the un-protected high-temperature alloy has been difficult to meet the harsh service environment of the hot end component. Thermal barrier coating (TBCs) can provide a thermal barrier between hot gas flow and engine components, so that the hot end component forms a temperature gradient along the thickness direction of the coating under high temperature load, reduces the heat transfer of high temperature gas to the base alloy, makes up for the shortage of allowable working temperature of the base high-temperature alloy component, and prolongs the service life of the component.

[0003] Among the commonly used thermal barrier coating materials at present, the ceramic layer material is Y2O3 stabilized ZrO2 (YSZ). YSZ is recognized as a standard ceramic thermal barrier coating material, which has high thermal expansion coefficient, low thermal conductivity and good thermal shock resistance, but the long-term use temperature cannot exceed 1200℃. Above 1200℃, the non-phase change tetragonal phase changes into tetragonal phase and cubic phase; during the cooling process, the tetragonal phase changes into monoclinic phase, which produces about 4% volume expansion and crack in the coating, thereby leading to coating peeling failure, and reducing the overall life of the thermal barrier coating.

[0004] The preparation process of new type of rare earth composite oxide ceramic coating at home and abroad mainly adopts atmospheric plasma spraying and suspension plasma spraying two process technologies. The shortcomings of these two methods are difficult to meet the needs of high temperature conditions such as sintering resistance of ceramic coating, interface bonding strength and high strain tolerance microstructure, and the coating prepared by these two processes has many holes, obvious defect morphology and inherent transverse cracks, etc., which will cause the short long-term peeling resistance life of the coating. SUMMARY

[0005] The present application is designed to provide a preparation method of chemical vapor deposition dysprosium hafnate ceramic coating in view of the above-mentioned prior art, and the purpose is to realize Dy2Hf2O7 as the ceramic coating of thermal barrier coating system, and for this purpose, the corresponding preparation process is researched and obtained, which fills the research gap at home and abroad.

[0006] The purpose of the present application is realized by the following technical scheme:

[0007] The method for preparing the chemical vapor deposition dysprosium hafnium oxide ceramic coating has the characteristics that: the method uses a chemical vapor deposition process, takes Dy and Hf metal particles and process gas as raw materials, first co-deposits Dy2O3 and HfO2 mixed oxides on the surface of a nickel-based high-temperature alloy, and then in-situ synthesizes a Dy2Hf2O7 ceramic coating with a fluorite structure at high temperature, and the process parameters of the method include:

[0008] A. The solid material is: Dy metal particles and Hf metal particles, and the purity of the metal particles is greater than 98%, and the size of the two kinds of metal particles is Φ5mm*3mm;

[0009] B. The process gas is: H2 gas, Ar gas, HCl gas and CO2 gas, and the purity is greater than 99.99%;

[0010] C. When Dy and Hf metal particles are used as raw materials to co-deposit Dy2O3 and HfO2 mixed oxides on the surface of a nickel-based high-temperature alloy, the H2 gas flow is 52L / min-68L / min, the HCl gas flow is 6.6L / min-8.2L / min, the CO2 gas flow is 38L / min-52L / min, the heating temperature of the vacuum chamber is 1180℃-1260℃, the vacuum degree of the vacuum chamber is 30mbar-60mbar, and the deposition time is 240min-300min;

[0011] D. When Dy and Hf metal particles are used as raw materials to in-situ synthesize a Dy2Hf2O7 ceramic coating at high temperature, the H2 gas flow is 42L / min-56L / min, the Ar gas flow is 18L / min-26L / min, the heating temperature of the vacuum chamber is 1340℃-1480℃, the vacuum degree of the vacuum chamber is 620mbar-740mbar, and the deposition time is 120min-180min.

[0012] The above technical solution uses Dy and Hf metal particles and related process gas as raw materials, uses chemical vapor deposition technology, controls the heating temperature, vacuum degree, process gas type and flow, deposition time and other factors of the vacuum chamber of the chemical vapor deposition equipment, first co-deposits Dy2O3 and HfO2 mixed oxides on the surface of a nickel-based high-temperature alloy, and then in-situ synthesizes a Dy2Hf2O7 ceramic coating with a fluorite structure at high temperature. The ceramic coating has the advantages of high-temperature phase structure stability, low thermal conductivity, sintering resistance, molten salt corrosion resistance and excellent strain tolerance, is suitable for use in high-temperature flame service conditions above 1300℃, and can improve the heat insulation effect of the thermal barrier coating of the turbine blade of an aero-engine.

[0013] In implementation, the surface of the nickel-based high-temperature alloy to be prepared with a coating is located directly above the Dy and Hf metal particles as ceramic targets, and the vertical distance therebetween is 350mm.

[0014] In the implementation, the process parameters are as follows:

[0015] C, when Dy2O3 and HfO2 mixed oxides are co-deposited on the surface of the nickel-based superalloy with Dy and Hf metal particles as raw materials, the H2 gas flow is 52 L / min, the HCl gas flow is 8.2 L / min, the CO2 gas flow is 38 L / min, the heating temperature of the vacuum chamber is 1180℃, the vacuum degree of the vacuum chamber is 60 mbar, and the deposition time is 300 min;

[0016] D, when Dy2Hf2O7 ceramic coating is synthesized in-situ at high temperature with Dy and Hf metal particles as raw materials, the H2 gas flow is 56 L / min, the Ar gas flow is 18 L / min, the heating temperature of the vacuum chamber is 1480℃, the vacuum degree of the vacuum chamber is 620 mbar, and the deposition time is 120 min.

[0017] In the implementation, the process parameters are as follows:

[0018] C, when Dy2O3 and HfO2 mixed oxides are co-deposited on the surface of the nickel-based superalloy with Dy and Hf metal particles as raw materials, the H2 gas flow is 68 L / min, the HCl gas flow is 6.6 L / min, the CO2 gas flow is 52 L / min, the heating temperature of the vacuum chamber is 1260℃, the vacuum degree of the vacuum chamber is 30 mbar, and the deposition time is 240 min;

[0019] D, when Dy2Hf2O7 ceramic coating is synthesized in-situ at high temperature with Dy and Hf metal particles as raw materials, the H2 gas flow is 42 L / min, the Ar gas flow is 26 L / min, the heating temperature of the vacuum chamber is 1340℃, the vacuum degree of the vacuum chamber is 740 mbar, and the deposition time is 180 min.

[0020] In the implementation, the process parameters are as follows:

[0021] C, when Dy2O3 and HfO2 mixed oxides are co-deposited on the surface of the nickel-based superalloy with Dy and Hf metal particles as raw materials, the H2 gas flow is 60 L / min, the HCl gas flow is 7.4 L / min, the CO2 gas flow is 45 L / min, the heating temperature of the vacuum chamber is 1220℃, the vacuum degree of the vacuum chamber is 45 mbar, and the deposition time is 270 min;

[0022] D, when Dy2Hf2O7 ceramic coating is synthesized in-situ at high temperature with Dy and Hf metal particles as raw materials, the H2 gas flow is 49 L / min, the Ar gas flow is 22 L / min, the heating temperature of the vacuum chamber is 1410℃, the vacuum degree of the vacuum chamber is 680 mbar, and the deposition time is 150 min.

[0023] The characteristics and beneficial effects of the technical scheme of the present application are as follows:

[0024] 1. The deposition temperature for preparing Dy2O3 and HfO2 mixed oxide on the surface of nickel-based superalloy is above 1180℃, and the vacuum degree is below 60mbar, which can ensure the reaction of Dy and Hf metal particles with HCl gas to form corresponding active precursors, improve the surface activity and spreadability of mixed oxide particles, avoid the residual and enrichment of loose and powdered oxide particles on the sample surface, and promote the adhesion of mixed oxide fine grains to the substrate interface;

[0025] 2. When synthesizing Dy2Hf2O7 ceramic coating in situ at high temperature, the solid phase reaction temperature is set to be above 1340℃, which can promote the mutual solid solution between mixed oxide particles, is beneficial to the high-temperature solid phase reaction of defect-type fluorite structure ceramic body, and avoids the residual of single oxide particles in the ceramic body due to incomplete solid solution. In addition, through the regulation of vacuum degree and Ar gas flow, the particle catalysis can also be achieved to accelerate the solid phase reaction synthesis rate;

[0026] 3. In the chemical vapor deposition process, through the reasonable design of HCl and CO2 gas flow, the composition ratio of Dy2O3 and HfO2 mixed oxide can be effectively controlled, the microcracks of the body oxide grains can be avoided while maintaining a high H2 gas flow in the vacuum chamber to improve the uniformity of heating temperature, and the solid solution and diffusion resistance between particles in the in-situ synthesis process at high temperature can be reduced, and the uniformity of the coating composition can be improved. DETAILED DESCRIPTION

[0027] The technical solutions of the present application will be further described in combination with the embodiments as follows:

[0028] In the following embodiments, the solid raw material for preparing the metal bonding layer is PtAl metal particles with a purity of more than 98%. The process gas for preparing the metal bonding layer is H2, Ar and HCl gas, all with a purity of more than 99.999%. The equipment for preparing the metal bonding layer is a chemical vapor deposition device.

[0029] The metal bonding layer is a metal transition layer on the surface of nickel-based single crystal superalloy, which is between the high-temperature alloy and the ceramic coating.

[0030] In the following embodiments, the equipment for preparing the dysprosium hafnate ceramic coating is a chemical vapor deposition device.

[0031] Embodiment 1:

[0032] The steps of the method for preparing the dysprosium hafnate ceramic coating by chemical vapor deposition according to the present application are as follows:

[0033] Step one, nickel-based single crystal superalloy pretreatment: 1000 grit sandpaper is used to pre-grind and remove the residues on the surface of the superalloy; before cleaning, a sandblasting machine is used to remove the oxide skin on the surface of the superalloy, the sand particles are less than 125 μm, and the working pressure is 0.2 MPa; after water sandblasting, tap water is used for flushing, deionized water is used for soaking, alcohol is used for dehydration, and drying is performed;

[0034] Step two, preparation of metal bonding layer: the nickel-based single crystal superalloy is loaded into a fixture, and the fixture is inserted into the gas outlet of the air guide pipe tool, vacuum is drawn and equipment pressure test is performed, and the deposition process parameters for preparing the PtAl metal bonding layer are as follows: heating furnace temperature 1070℃, reaction chamber vacuum degree 230mbar, H2 gas flow rate 36L / min, Ar gas flow rate 14L / min, HCl gas flow rate 5.5L / min, and deposition time 420min;

[0035] Step three, preparation of dysprosium hafnate ceramic coating: the sample with the prepared metal bonding layer is hung on a superalloy support by using a NiCr wire, and Dy and Hf metal particles are placed in a graphite tank in a vacuum chamber of a chemical vapor deposition device, vacuum is drawn and equipment pressure test is performed, and the deposition process parameters for preparing the dysprosium hafnate ceramic coating are as follows: first, the preparation parameters of the mixed oxide of Dy2O3 and HfO2 are as follows: H2 gas flow rate 52L / min, HCl gas flow rate 8.2L / min, CO2 gas flow rate 38L / min, heating temperature of the vacuum chamber 1180℃, vacuum degree of the vacuum chamber 60mbar, and deposition time 300min; second, after the mixed oxide is prepared, the HCl and CO2 gas flow meters are closed, the temperature is continuously increased to the set temperature in the same vacuum chamber, and the Ar gas flow meter is opened, and the preparation process parameters of the dysprosium hafnate ceramic coating are as follows: H2 gas flow rate 56L / min, Ar gas flow rate 18L / min, heating temperature of the vacuum chamber 1480℃, vacuum degree of the vacuum chamber 620mbar, and deposition time 120min.

[0036] Example 2:

[0037] The method for preparing the dysprosium hafnate ceramic coating by chemical vapor deposition comprises the following steps:

[0038] Step one, nickel-based single crystal superalloy pretreatment: 1000 grit sandpaper is used to pre-grind and remove the residues on the surface of the superalloy; before cleaning, a sandblasting machine is used to remove the oxide skin on the surface of the superalloy, the sand particles are less than 125 μm, and the working pressure is 0.2 MPa; after water sandblasting, tap water is used for flushing, deionized water is used for soaking, alcohol is used for dehydration, and drying is performed;

[0039] Step two, preparing the metal bonding layer: the nickel-based single crystal superalloy is loaded into a fixture, and the fixture is inserted into the gas outlet of the air guide pipe tool, vacuum is drawn and equipment pressure test is carried out, the deposition process parameters for preparing the PtAl metal bonding layer are as follows: heating furnace temperature 1070 DEG C, reaction chamber vacuum degree 230 mbar, H2 gas flow 36 L / min, Ar gas flow 14 L / min, HCl gas flow 5.5 L / min, deposition time 420 min;

[0040] Step three, preparing the dysprosium hafnate ceramic coating: the sample with the prepared metal bonding layer is hung on a high-temperature alloy support by using a NiCr wire, and Dy and Hf metal particles are placed in a graphite tank in a vacuum chamber of a chemical vapor deposition device, vacuum is drawn and equipment pressure test is carried out, and the deposition process for preparing the dysprosium hafnate ceramic coating is as follows: first, the preparation parameters of the mixed oxide of Dy2O3 and HfO2 are as follows: H2 gas flow 68 L / min, HCl gas flow 6.6 L / min, CO2 gas flow 52 L / min, heating temperature of the vacuum chamber 1260 DEG C, vacuum degree of the vacuum chamber 30 mbar, and deposition time 240 min; second, after the mixed oxide is prepared, the HCl and CO2 gas flow meters are closed, the temperature in the same vacuum chamber is continuously increased to the set temperature, the Ar gas flow meter is opened, and the preparation process parameters of the in-situ synthesized Dy2Hf2O7 ceramic coating are as follows: H2 gas flow 42 L / min, Ar gas flow 26 L / min, heating temperature of the vacuum chamber 1340 DEG C, vacuum degree of the vacuum chamber 740 mbar, and deposition time 180 min.

[0041] Example 3:

[0042] The method for preparing the dysprosium hafnate ceramic coating by chemical vapor deposition comprises the following steps:

[0043] Step one, pretreatment of the nickel-based single crystal superalloy: 1000 mesh sandpaper is used to pre-grind and remove the residues on the surface of the superalloy; before cleaning, a sandblasting machine is used to perform sandblasting treatment to remove the oxide skin on the surface of the superalloy, the sand particles are less than 125 mu m, and the working pressure is 0.2 MPa; after water sandblasting, the superalloy is washed with tap water, soaked in deionized water, dehydrated with alcohol, and dried;

[0044] Step two, preparing the metal bonding layer: the nickel-based single crystal superalloy is loaded into a fixture, and the fixture is inserted into the gas outlet of the air guide pipe tool, vacuum is drawn and equipment pressure test is carried out, the deposition process parameters for preparing the PtAl metal bonding layer are as follows: heating furnace temperature 1070 DEG C, reaction chamber vacuum degree 230 mbar, H2 gas flow 36 L / min, Ar gas flow 14 L / min, HCl gas flow 5.5 L / min, deposition time 420 min;

[0045] Step three, preparation of dysprosium hafnate ceramic coating: the sample with prepared metal bonding layer is hung on a high-temperature alloy support with a NiCr wire, and Dy and Hf metal particles are placed in a graphite tank in a vacuum chamber of a chemical vapor deposition device. The vacuum is pumped and the device is tested for pressure retention. The deposition process for preparing the dysprosium hafnate ceramic coating is as follows: first, the preparation parameters of the mixed oxide of Dy2O3 and HfO2 are as follows: H2 gas flow rate 60 L / min, HCl gas flow rate 7.4 L / min, CO2 gas flow rate 45 L / min, vacuum chamber heating temperature 1220℃, vacuum chamber vacuum degree 45mbar, and deposition time 270min; second, after the mixed oxide is prepared, the HCl and CO2 gas flow meters are closed, the temperature in the same vacuum chamber is continued to be raised to the set temperature, and the Ar gas flow meter is opened. The preparation process parameters of the in-situ high-temperature synthesis of the Dy2Hf2O7 ceramic coating are as follows: H2 gas flow rate 49 L / min, Ar gas flow rate 22 L / min, vacuum chamber heating temperature 1410℃, vacuum chamber vacuum degree 680mbar, and deposition time 150min.

[0046] The above embodiment has the advantage over the prior art that in the chemical vapor deposition process, the mixed oxide of Dy2O3 and HfO2 is first co-deposited in the same vacuum chamber, and then the Dy2Hf2O7 ceramic coating with a fluorite structure is in-situ synthesized at high temperature. The composition of the prepared ceramic coating meets the stoichiometric ratio design value, and has a strain-tolerant columnar crystal microstructure. The coating system has low thermal conductivity and high-temperature sintering resistance, which can improve the thermal insulation efficiency of the thermal barrier coating at higher service temperatures. This type of ceramic coating is suitable for use in high-temperature flame service conditions of 1300℃ and above.

Claims

1. A method of chemical vapor deposition of a dysprosium hafnate ceramic coating, characterized by: The method adopts chemical vapor deposition process, uses Dy and Hf metal particles and process gas as raw materials, first co-deposits Dy2O3 and HfO2 mixed oxide on the surface of nickel-based superalloy, and then in-situ synthesizes Dy2Hf2O7 ceramic coating with fluorite structure at high temperature, and the process parameters of the method include: A. The solid material is Dy metal particles and Hf metal particles, the purity of the metal particles is greater than 98%, and the size of the two metal particles is Φ5mm*3mm; B. The process gas is H2 gas, Ar gas, HCl gas and CO2 gas, and the purity is greater than 99.99%; C. When Dy and Hf metal particles are used as raw materials to co-deposit Dy2O3 and HfO2 mixed oxide on the surface of nickel-based superalloy, the H2 gas flow is 52L / min-68L / min, the HCl gas flow is 6.6L / min-8.2L / min, the CO2 gas flow is 38L / min-52L / min, the heating temperature of the vacuum chamber is 1180℃-1260℃, the vacuum degree of the vacuum chamber is 30mbar-60mbar, and the deposition time is 240min-300min; D. When Dy and Hf metal particles are used as raw materials to in-situ synthesize Dy2Hf2O7 ceramic coating at high temperature, the H2 gas flow is 42L / min-56L / min, the Ar gas flow is 18L / min-26L / min, the heating temperature of the vacuum chamber is 1340℃-1480℃, the vacuum degree of the vacuum chamber is 620mbar-740mbar, and the deposition time is 120min-180min.

2. The method of chemical vapor deposition of a dysprosium hafnate ceramic coating according to claim 1, characterized in that: The surface of the nickel-based superalloy to be prepared with the coating is located directly above the Dy and Hf metal particles as the ceramic target, and the vertical distance therebetween is 350mm.

3. The method of chemical vapor deposition of a dysprosium hafnate ceramic coating according to claim 1, characterized in that: In the process parameters: C. When Dy and Hf metal particles are used as raw materials to co-deposit Dy2O3 and HfO2 mixed oxide on the surface of nickel-based superalloy, the H2 gas flow is 52L / min, the HCl gas flow is 8.2L / min, the CO2 gas flow is 38L / min, the heating temperature of the vacuum chamber is 1180℃, the vacuum degree of the vacuum chamber is 60mbar, and the deposition time is 300min; D. When Dy and Hf metal particles are used as raw materials to in-situ synthesize Dy2Hf2O7 ceramic coating at high temperature, the H2 gas flow is 56L / min, the Ar gas flow is 18L / min, the heating temperature of the vacuum chamber is 1480℃, the vacuum degree of the vacuum chamber is 620mbar, and the deposition time is 120min.

4. The method of chemical vapor deposition of a dysprosium hafnate ceramic coating of claim 1, wherein: In the process parameters: C. When Dy and Hf metal particles are used as raw materials to co-deposit Dy2O3 and HfO2 mixed oxide on the surface of nickel-based superalloy, the H2 gas flow is 68L / min, the HCl gas flow is 6.6L / min, the CO2 gas flow is 52L / min, the heating temperature of the vacuum chamber is 1260℃, the vacuum degree of the vacuum chamber is 30mbar, and the deposition time is 240min; D. When Dy2Hf2O7 ceramic coating is in-situ synthesized at high temperature using Dy and Hf metal particles as raw materials, the H2 gas flow is 42 L / min, the Ar gas flow is 26 L / min, the heating temperature of the vacuum chamber is 1340 °C, the vacuum degree of the vacuum chamber is 740 mbar, and the deposition time is 180 min.

5. The method of chemical vapor deposition of a dysprosium hafnate ceramic coating of claim 1, wherein: In the process parameters: C. When Dy2O3 and HfO2 mixed oxides are co-deposited on the surface of a nickel-based high-temperature alloy using Dy and Hf metal particles as raw materials, the H2 gas flow is 60 L / min, the HCl gas flow is 7.4 L / min, the CO2 gas flow is 45 L / min, the heating temperature of the vacuum chamber is 1220 °C, the vacuum degree of the vacuum chamber is 45 mbar, and the deposition time is 270 min; D. When Dy2Hf2O7 ceramic coating is in-situ synthesized at high temperature using Dy and Hf metal particles as raw materials, the H2 gas flow is 49 L / min, the Ar gas flow is 22 L / min, the heating temperature of the vacuum chamber is 1410 °C, the vacuum degree of the vacuum chamber is 680 mbar, and the deposition time is 150 min.