CN115074723B - A kind of preparation method of high temperature thermal barrier coating on the surface of molybdenum alloy - Google Patents

Abstract

The invention discloses a method for preparing a high-temperature thermal barrier coating on the surface of a molybdenum alloy, comprising: S1, pretreatment of the molybdenum alloy plate: grinding the surface of the molybdenum alloy plate, ultrasonic cleaning, and drying; S2, preparing the middle layer material: the middle layer material Zirconia powder; S3, preparation of thermal barrier coating materials: thermal barrier coating materials include: Cr: 2.0-5.0wt%; Ti: 1.0-2.0wt%; Ni: 2.0-3.0wt%; Mn: 0.1-0.5 wt%; B: 0.5-1.0wt% and the remainder MoSi ₂ ; S4, preparing the intermediate layer: applying the intermediate layer material on the surface of the pretreated molybdenum alloy plate, and sintering to form the intermediate layer; S5, preparing a preset powder coating : mixing the thermal barrier coating material with the binder to form a coating slurry, applying the coating slurry on the intermediate layer, and drying to obtain a preset powder coating; S6, preparing a high-temperature thermal barrier coating: for the preset powder The coating is laser clad to obtain a high temperature thermal barrier coating on the intermediate layer. The process of the invention is simple, and can improve the working life, bonding strength and high temperature oxidation resistance of the thermal barrier coating at high temperature.

Description

A kind of preparation method of high temperature thermal barrier coating on the surface of molybdenum alloy

technical field

The invention relates to the field of high-temperature thermal barrier protection of refractory metals, in particular to a method for preparing a high-temperature thermal barrier coating on the surface of a molybdenum alloy.

Background technique

Refractory metal molybdenum alloy has good strength and thermal stability at high temperature, low thermal expansion coefficient, excellent thermal conductivity, electrical conductivity and good corrosion resistance. It has a good prospect in high-temperature service occasions, but due to the low-temperature brittleness and high-temperature oxidation resistance of molybdenum alloy itself, it cannot maintain good performance in high-temperature occasions, and at the same time, "catastrophic" oxidation will occur. Stable working efficiency is achieved at high temperature, which also limits the application range of molybdenum alloys in high temperature service occasions.

A large number of projects have proved that silicide coatings have broad prospects for high-temperature thermal barrier protection. MoSi ₂ , as one of the typical silicide coating materials, has excellent service performance at high temperatures, high hardness and wear resistance, and has Excellent high temperature oxidation resistance, Si element forms dense amorphous SiO ₂ with oxygen on the coating surface at high temperature, SiO ₂ can isolate the substrate from reacting with oxygen, and SiO ₂ has a certain self-healing ability to repair the coating at high temperature The micro-cracks generated under it can effectively protect the matrix. However, the coating prepared from pure MoSi ₂ is relatively brittle and prone to cracks during use. The linear expansion coefficient of the molybdenum alloy and the pure MoSi ₂ coating is quite different, and the bonding to the substrate is weak, and the coating is prone to peeling off. Therefore, it is necessary to add alloying elements on the basis of pure _MoSi2 coating to make up for the defects between the coating and the substrate.

Contents of the invention

The purpose of the present invention is to provide a high-temperature thermal barrier coating on the surface of molybdenum alloy for the defects that the coating prepared from pure _MoSi2 is relatively brittle, prone to cracks and weak bonding between the coating and the substrate during use. Layer preparation methods to solve the above-mentioned existing problems.

The present invention is achieved through the following technical solutions:

A method for preparing a high temperature thermal barrier coating on the surface of a molybdenum alloy, characterized in that the method comprises the following steps:

S1. Pretreatment of molybdenum alloy sheet: Grinding and polishing the surface of molybdenum alloy sheet to remove surface scale, then ultrasonic cleaning, drying, and stand-by;

S2, preparing the intermediate layer material: the intermediate layer material is zirconia powder;

S3. Preparation of thermal barrier coating material: The thermal barrier coating material is composed of the following components: Cr powder 2.0-5.0wt%; Ti powder 1.0-2.0wt%; Ni powder 2.0-3.0wt%; Mn powder 0.1 -0.5wt%; B powder 0.5-1.0wt% and the balance MoSi ₂ powder;

S4. Prepare the intermediate layer: apply the intermediate layer material on the surface of the pretreated molybdenum alloy plate, and then sinter to form the intermediate layer;

S5. Prepare a preset powder coating: mix the thermal barrier coating material with a binder to form a coating slurry, then apply the coating slurry on the intermediate layer, and obtain the preset powder coating after drying. powder coating;

S6. Preparing a high-temperature thermal barrier coating: performing laser cladding on the preset powder coating to obtain a high-temperature thermal barrier coating on the intermediate layer.

Specifically, the preparation method of the high-temperature thermal barrier coating on the surface of the molybdenum alloy developed by the present invention is based on the difference in thermal expansion coefficient between the _MoSi2 coating and the molybdenum alloy, which will lead to poor bonding strength of the coating and easy peeling off of the coating. When using ZrO ₂ Material Molybdenum alloy surface prepares an intermediate layer in advance, its function is mainly to increase the bonding strength between the MoSi ₂ coating and the substrate, and ZrO ₂ can also play a toughening and strengthening role. Adding a small amount of beneficial alloying elements to the pure MoSi ₂ coating can improve the performance of the coating. The alloying of the MoSi ₂ coating is beneficial to the bonding between the coating and the substrate, and at the same time can alleviate the brittleness of the coating, further improve the stability of the coating under high temperature use, and prolong the service life of the coating.

The invention can improve the working life, bonding strength and high temperature oxidation resistance of the thermal barrier coating at high temperature.

Further, a method for preparing a high-temperature thermal barrier coating on the surface of a molybdenum alloy: step S1, pretreatment of the molybdenum alloy sheet: wherein the thickness of the molybdenum alloy sheet is 3-10 mm.

Further, a method for preparing a high-temperature thermal barrier coating on the surface of a molybdenum alloy: step S2, preparing an intermediate layer material: the intermediate layer material is zirconia powder, which is ball milled; wherein the purity of the zirconia powder is not less than 99%; the ball milling speed is 100-150 rpm, the ball milling time is 10-15 hours, and the particle size of the zirconia powder particles after ball milling is 8-10 μm.

Further, a method for preparing a high-temperature thermal barrier coating on the surface of a molybdenum alloy: step S3, preparing a thermal barrier coating material: the preparation process of the thermal barrier coating material is: according to the mass fraction, the Cr powder 2.0- 5.0wt%, Ti powder 1.0-2.0wt%, Ni powder 2.0-3.0wt%, Mn powder 0.1-0.5wt%, B powder 0.5-1.0wt%, and the balance MoSi ₂ powder were mixed and ball milled to obtain MoSi ₂ Powder-based mixed alloy powder; wherein: the ball milling speed is 120-150rpm, and the ball milling time is 12-15 hours.

Further, a method for preparing a high-temperature thermal barrier coating on the surface of a molybdenum alloy: step S3, preparation of thermal barrier coating materials: the particle size of each powder after ball milling is as follows:

The purity of Cr powder is not less than 97%, and the particle size of the powder is 3-4μm;

The purity of Ti powder is not less than 95%, and the particle size of the powder is 3-5 μm;

The purity of Ni powder is not less than 97%, and the particle size of the powder is 4-6 μm;

The purity of Mn powder is not less than 98%, and the particle size of the powder is 2-3μm;

The purity of B powder is not less than 95%, and the particle size of the powder is 2-3 μm;

The purity of MoSi ₂ powder is not less than 99%, and the powder particle size is 3-5 μm.

Specifically, the purity and particle size of each metal are preferred in the present invention. If the powder purity is low, more impurities will be formed during the cladding process, which will reduce the coating quality; if the powder particles are too large, it will easily fail to fully melt during the cladding process, and agglomerates will appear in the coating, and holes will appear, reducing the coating quality. layer quality.

Further, a method for preparing a high-temperature thermal barrier coating on the surface of a molybdenum alloy: step S4, preparing an intermediate layer: apply the intermediate layer material on the surface of the pretreated molybdenum alloy plate, and then adopt a spark plasma sintering method , Sintered to form a 0.1-0.5mm thick middle layer.

Further, a method for preparing a high-temperature thermal barrier coating on the surface of a molybdenum alloy: step S4, preparing an intermediate layer: wherein the process parameters of the spark plasma sintering method are: sintering temperature 1800-2000°C, sintering pressure 30-40MPa, sintering Time 5-7 minutes.

Further, a method for preparing a high-temperature thermal barrier coating on the surface of a molybdenum alloy: step S5, preparing a preset powder coating: mixing the thermal barrier coating material with a binder to form a coating slurry, and then applying the The coating slurry is applied on the intermediate layer, and the preset powder coating is obtained after drying; wherein: the binder is acetone; the mass ratio of the thermal barrier coating material to the binder is It is 1: (0.6-1); the thickness of the preset powder coating is 1-2mm, and it is dried at 110-130° C. for 5-15 minutes.

Preferably, the thickness of the preset powder coating in the present invention is 1-2 mm, and the preset powder coating is too thick to fully melt the alloy powder in the molten pool; the preset powder coating is too thin, and the laser protection gas is easy to blow the powder away , will form droplet splashing, and the quality of the formed coating is poor.

Further, a method for preparing a high-temperature thermal barrier coating on the surface of a molybdenum alloy: step S6, preparing a high-temperature thermal barrier coating: performing laser cladding on the preset powder coating, and obtaining a 1-2 mm Thick high-temperature thermal barrier coating; wherein: the laser cladding is carried out on YLS-4000 laser surface modification equipment, and the laser process parameters are 20mm in height, 4.2mm in spot diameter, 30% overlap rate, and laser power of 3000-3500W, scanning speed 5-8mm/s, argon gas flow 10-20L/min.

The coating preparation methods adopted in the present invention are spark plasma sintering technology and laser cladding technology. The spark plasma sintering technology generally adopts the method of pressure sintering, and the prepared coating structure is dense and uniform. Laser cladding technology has a good prospect in the field of coating preparation due to its low dilution, high material utilization, stable heat source and fast cooling rate. The pre-prepared powder coating prepared by irradiating the surface of the substrate with a high-energy laser beam will rapidly melt and solidify the powder, forming a layer of silicide coating with good surface quality on the surface of the substrate. During the cladding process, there is no droplet splashing phenomenon, the cladding process is stable, the cladding efficiency is high, and automatic production can be realized. Therefore, the present invention adopts the laser cladding technology to prepare the coating, which has high theoretical value and practical significance.

Beneficial effects of the present invention:

(1) The process of the present invention utilizes the intermediate layer structure prepared by spark plasma sintering technology to be dense and uniform, and the sintering period can save energy consumption, and obtain a _ZrO2 coating (intermediate layer) with fine grain fine mechanical properties; then use preset powder The coating is prepared by laser cladding, and the mixed alloy powder is fused on the surface of the substrate by laser cladding, and at the same time, it is melted and bonded with the spark plasma sintered intermediate layer. Laser cladding has concentrated energy and low heat loss. It can quickly form a molten pool on the substrate to melt the alloy powder and the substrate. In the molten pool, the alloying elements and the molybdenum substrate dissolve and diffuse to form intermetallic compounds. At the same time, the cooling rate of laser cladding is relatively high, and a transition zone of metallurgical bonding is formed between the coating and the substrate. The addition of alloying elements in the coating can have a beneficial effect on the transition zone of metallurgical bonding, optimizing the relationship between the coating and the substrate. The combination of the Mn element in the mixed alloy powder is beneficial to the corrosion of the coating by oxygen in the high-temperature service environment, and the deoxidation of the Mn element and the continuous and dense SiO ₂ film synergistically reduce the impact of oxygen on the coating and the substrate. Even under the action of thermal stress, the coating cracks and oxidation channels are formed, and the Mn element can still reduce the influence of oxygen on the coating and molybdenum substrate. Part of the powder that has not been melted in time will form an agglomeration area at the bottom of the molten pool, and defects such as pores and cracks are prone to occur. In order to enhance the bonding between the coating and the substrate and reduce defects such as pores and cracks in the coating, the present invention uses _MoSi2 as The coating is prepared by mixing the main alloy powder, and the alloying elements go through the process of wetting, dissolving and diffusing to enhance the bonding between the coating and the substrate and reduce defects such as pores and cracks.

(2) The present invention adopts the _{ZrO2 intermediate} layer prepared by spark plasma sintering, which has a dense and uniform structure, fine grains, and short sintering time to save energy loss. The high-temperature bonding strength of the layer can be improved. The laser cladding technology of the present invention prepares high-temperature thermal barrier coatings. It is carried out on YLS-4000 laser surface modification equipment. The cladding process is stable and uniform. Due to the protection of argon gas, there is no oxidation and burning during the cladding process. The laser energy density Higher, can melt the material in a short time, the heat is concentrated, the heat loss is small, the material utilization rate is high, and it is suitable for the automatic production process.

(3) The coating prepared by the present invention has a complete and uniform macroscopic appearance, no defects such as obvious cracks and pores, good metallurgical bonding between the coating and the substrate, compact structure, and fine grains. In the present invention, the addition of alloying elements plays a role in evolution and has a beneficial effect on the performance and service life of the coating: the Cr element plays a role in refining the crystal grains and also has a beneficial effect on the hardness of the coating The addition of Ti element is helpful to the high temperature resistance of the coating. Ti and Si form Ti ₅ Si ₃ phase in the coating, which enhances the hardness of the coating. At the same time, the bonding force between Ti atoms and Si atoms is high. It is beneficial to the metallurgical bonding between the coating and the substrate; Ni element is a commonly used alloy element in normal high temperature occasions, Ni element has good structural stability at high temperature, forms intermetallic compounds, and strengthens the coating performance. It has good high-temperature anti-oxidation effect, which is beneficial to the service life of the coating at high temperature; the addition of B element is conducive to the formation of borosilicate film on the surface of the coating to improve the high-temperature oxidation resistance of the coating; Mn element has the effect of deoxidation, At high temperature, the Mn element has high activity and is preferentially combined with oxygen. At the same time, the Si element combines with oxygen to form a continuous and dense SiO ₂ film. Under the protection of the SiO ₂ film, the Mn element deoxidizes to reduce the erosion of oxygen on the coating at high temperature. The high-temperature thermal barrier coating prepared by the method of the present invention has undergone 10 cycles of oxidation experiments at 1300°C. The coating does not appear to fall off, and the oxidation weight gain is 0.412 mg/cm ² . In the oxidation experiment at 630°C, the coating The quality of the layer is good, and there is no "Pesting" phenomenon (referring to a phenomenon that can cause the alloy to crack into small molecules or powder). In terms of coating hardness, the hardness of the MoSi ₂ coating without alloying elements is about 863HV, and the hardness of the coating after adding alloying elements is about 1179HV, and the hardness of the coating with alloying elements is 1.3 times that of the coating without alloying elements .

(4) The alloying of MoSi ₂ coating can effectively reduce defects such as cracks and pores. During the use of the coating, the alloying elements can stabilize the performance, strengthen the high temperature oxidation resistance of the coating at high temperature, and effectively cope with the high temperature and complex environment. The lack of performance defects of the undercoat layer provides good practical significance for the performance optimization design of high temperature thermal barrier coatings.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Apparently, the described embodiments are only some of the embodiments of the present invention, not all of them. The following description of at least one exemplary embodiment is merely illustrative in nature and in no way taken as limiting the invention, its application or uses. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Example 1

A method for preparing a high-temperature thermal barrier coating on a molybdenum alloy surface, comprising the following specific steps:

S1. Pretreatment of molybdenum alloy plates: Grinding and polishing the surface of molybdenum alloy plates with a thickness of 4 mm to remove surface scale, then cleaning and drying with an ultrasonic cleaning machine, and set aside;

S2, preparation of the intermediate layer material: _ZrO powder with a purity of 99% was milled in a ball mill at 120 r/mm for 15 hours to obtain a powder with a particle size of 8 μm, which was the intermediate layer material;

S3. Preparation of thermal barrier coating materials: by mass fraction, Cr powder 2.0wt% (purity 97%); Ti powder 1.0wt% (purity 95%); Ni powder 2.0wt% (purity 97%); Mn powder 0.1 wt% (purity 98%); B powder 0.5wt% (purity 95%) and balance MoSi ₂ powder (94.4wt%, purity 99%) carry out ball milling (ball mill speed 120r/mm, ball milling 15 hours), obtain MoSi ₂ powder-based mixed alloy powder;

S4, prepare the intermediate layer: apply the above-mentioned intermediate layer material on the surface of the pretreated molybdenum alloy plate, and then use the spark plasma sintering method to sinter to form a 0.3mm thick intermediate layer; wherein: the sintering process parameters are: the sintering temperature is 1800°C, sintering pressure 30MPa, sintering time 7 minutes;

S5. Preparing a pre-set powder coating: mixing the above thermal barrier coating material with acetone at a mass ratio of 1:0.6 to form a coating slurry, and then applying the coating slurry on the intermediate layer, Dry at 120°C for 10 minutes to obtain a 1.5mm thick pre-powder coating;

S6. Preparation of high-temperature thermal barrier coating: use YLS-4000 laser surface modification equipment to carry out laser cladding on the above-mentioned preset powder coating, and the coating prepared on the surface of the molybdenum alloy has a uniform surface, a dense structure, and a thickness of about 1.3mm. Among them: laser cladding process parameters are height 20mm, spot diameter 4.2mm, overlap rate 30%, laser power 3000W, scanning speed 6mm/s, argon gas volume 15L/min.

Example 2

A method for preparing a high-temperature thermal barrier coating on a molybdenum alloy surface, comprising the following specific steps:

S1. Pretreatment of molybdenum alloy plates: Grinding and polishing the surface of molybdenum alloy plates with a thickness of 4 mm to remove surface scale, then cleaning and drying with an ultrasonic cleaning machine, and set aside;

S2, prepare the intermediate layer material: ZrO ₂ powder with a purity of 99% is ball milled for 13 hours at 100 r/mm in a ball mill to obtain a powder with a particle size of 10 μm, which is the intermediate layer material;

S3, preparing thermal barrier coating materials: by mass fraction, 3.0wt% of Cr powder; 2.0wt% of Ti powder; 2.0wt% of Ni powder; 0.3wt% of Mn powder; 0.8wt% of B powder and the balance MoSi ₂ powder ( 91.9wt%) to carry out ball milling (ball mill rotating speed 150r/mm, ball milling 10 hours), obtain the mixed alloy powder based on _MoSi2 powder;

S4. Preparation of the intermediate layer: apply the above-mentioned intermediate layer material on the surface of the pretreated molybdenum alloy plate, and then use the spark plasma sintering method to sinter to form the intermediate layer; wherein: the sintering process parameters are: the sintering temperature is 1900 ° C, the sintering The pressure is 35MPa, and the sintering time is 6 minutes;

S5. Preparing a pre-set powder coating: mixing the above-mentioned thermal barrier coating material and acetone at a mass ratio of 1:1 to form a coating slurry, and then applying the coating slurry on the intermediate layer, Dry at 130°C for 15 minutes to obtain a 1.5mm thick pre-powder coating;

S6. Preparation of high-temperature thermal barrier coating: use YLS-4000 laser surface modification equipment to carry out laser cladding on the above-mentioned preset powder coating, and the coating prepared on the surface of molybdenum alloy has a uniform surface, dense structure, and a thickness of about 1.6mm Among them: laser cladding process parameters are height 20mm, spot diameter 4.2mm, overlap rate 30%, laser power 3500W, scanning speed 7mm/s, argon gas volume 15L/min.

Example 3

A method for preparing a high-temperature thermal barrier coating on a molybdenum alloy surface, comprising the following specific steps:

S1. Pretreatment of molybdenum alloy plates: Grinding and polishing the surface of molybdenum alloy plates with a thickness of 4 mm to remove surface scale, then cleaning and drying with an ultrasonic cleaning machine, and set aside;

S2, preparation of the intermediate layer material: ZrO ₂ powder with a purity of 99% was ball milled at 110 r/mm in a ball mill for 10 hours to obtain a powder with a particle size of 9 μm, which is the intermediate layer material;

S3, preparing thermal barrier coating materials: by mass fraction, 4.0wt% of Cr powder; 2.0wt% of Ti powder; 2.5wt% of Ni powder; 0.3wt% of Mn powder; 0.8wt% of B powder and the balance MoSi ₂ powder ( 90.4wt%) to carry out ball milling (ball mill speed 130r/mm, ball milling 12 hours), obtain the mixed alloy powder based on _MoSi2 powder;

S4. Prepare the intermediate layer: apply the above-mentioned intermediate layer material on the surface of the pretreated molybdenum alloy plate, and then use the spark plasma sintering method to sinter to form the intermediate layer; wherein: the sintering process parameters are: the sintering temperature is 2000 ° C, the sintering The pressure is 32MPa, and the sintering time is 7 minutes;

S5. Preparing a pre-set powder coating: mixing the above-mentioned thermal barrier coating material and acetone at a mass ratio of 1:1 to form a coating slurry, and then applying the coating slurry on the intermediate layer, Dry at 110°C for 10 minutes to obtain a 1.5mm thick pre-powder coating;

S6. Preparation of high-temperature thermal barrier coating: use YLS-4000 laser surface modification equipment to carry out laser cladding on the above-mentioned preset powder coating, and the coating prepared on the surface of molybdenum alloy has a uniform surface, dense structure, and a thickness of about 1.8mm Among them: laser cladding process parameters are height 20mm, spot diameter 4.2mm, overlap rate 30%, laser power 3500W, scanning speed 8mm/s, argon gas volume 15L/min.

Comparative example 1

A method for preparing a high-temperature thermal barrier coating on a molybdenum alloy surface, comprising the steps of:

(1) Grinding and polishing the molybdenum alloy plate surface oxide with a thickness of 4mm, cleaning and drying with an ultrasonic cleaner;

(2) The mass percentage composition is 100wt% ZrO ₂ , 94.4wt% MoSi ₂ , 2wt% Cr, 1wt% Ti, 2wt% Ni, 0.1wt% Mn, 0.5wt% B for ball milling to obtain mainly MoSi ₂ powder The mixed alloy powder; the ball milling time is 15h, the ball mill speed is 120r/mm; the ZrO ₂ composite powder has a purity of 99%, and a particle diameter of 8-10μm; the MoSi ₂ powder has a purity of 99%, and a particle diameter of 3-5μm; Cr powder The purity is 97%, and the particle diameter is 3-4μm; the purity of Ti powder is 95%, and the particle diameter is 3-5μm; the purity of Ni powder is 97%, and the particle diameter is 4-6μm; the purity of Mn powder is 98%, and the particle diameter is 2-3μm; B powder purity is 95%, particle diameter is 2-3μm;

(3) After ball milling, ZrO ₂ powder is uniformly pre-placed on the polished molybdenum alloy plate, and the coating is sintered by spark plasma sintering technology. The sintering process parameters are: sintering temperature 1800°C, sintering pressure 30MPa, sintering time For 7 minutes, the above-mentioned mixed alloy powder is preset on the intermediate layer, using acetone as a binder, and the pre-coated coating is placed in a drying oven at 120 ° C for 10 minutes to obtain a preset powder coating with a thickness of 1.5mm;

(4) Utilize YLS-4000 laser surface modification equipment to carry out laser cladding to the preset powder coating, and the described laser cladding process parameters are height 20mm, spot diameter 4.2mm, lap rate 30%, laser power: 3000W, scanning speed of 6mm/s, argon gas volume of 15L/min, the surface of the coating prepared on the molybdenum alloy surface is uniform, the structure is dense, and the thickness is about 1.3mm. High temperature thermal barrier coating.

The high-temperature thermal barrier coatings prepared in Comparative Example 1 and Example 1 have little difference in thickness, and the prepared coating structure is in the form of dendrite growth. This is due to the characteristics of high cooling rate of laser cladding. The coating There are no defects such as cracks and pores, which shows that the molten pool formed by laser cladding melts the alloy powder evenly. However, the metallurgical bonding effect between the coating prepared in Comparative Example 1 and the molybdenum alloy substrate is poor, which is due to the difference in the coefficient of linear expansion of the alloy components in the substrate and the coating. The coating prepared in Example 1 has a good metallurgical bonding effect after the _ZrO2 intermediate layer is prepared by spark plasma sintering in advance, and after adding alloy elements, the coating does not have defects such as cracks and pores, and the hardness of the coating is also improved.

Test: Test the interface strength and high-temperature performance of the above-mentioned Examples 1-3 and Comparative Example 1, and use the Vickers hardness indentation method to test the interface bonding strength of the coating. Calculate the interface bonding strength according to the formula C∝P ⁿ , where n is affected by the thickness of the coating, C is the crack length, and P is the indentation load. The high-temperature service performance is tested with a KBS1400 heating furnace, and the temperature is set at 1300°C; see Table 1 for specific test results.

Table 1 is the test result of above-mentioned embodiment 1-3 and comparative example 1 coating performance

From the above test results in Table 1, it can be seen that the working life and bonding strength of the high temperature thermal barrier coating prepared in the present invention are significantly improved at high temperature. The invention adopts the mixed alloy powder mainly composed of _MoSi2 to prepare the coating, and the alloy elements go through the process of wetting, dissolving and diffusing to enhance the bonding between the coating and the substrate, reduce defects such as pores and cracks, and improve the high-temperature service performance.

The above-mentioned preferred embodiments of the present invention are only used to explain the present invention, and are not intended to limit the present invention. All obvious changes or changes derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims (9)

1. The preparation method of the molybdenum alloy surface high-temperature heat barrier coating is characterized by comprising the following steps:

s1, pretreatment of a molybdenum alloy plate: polishing the surface of the molybdenum alloy plate, removing surface oxide skin, then ultrasonically cleaning and drying for later use;

s2, preparing an intermediate layer material: the intermediate layer material is zirconia powder;

s3, preparing a thermal barrier coating material: the thermal barrier coating material consists of the following components: 2.0-5.0wt% of Cr powder; 1.0 to 2.0wt% of Ti powder; 2.0 to 3.0wt% of Ni powder; mn powder 0.1-0.5wt%; 0.5-1.0wt% of B powder and the balance MoSi ₂ A powder;

s4, preparing an intermediate layer: coating the intermediate layer material on the surface of the pretreated molybdenum alloy plate, and then sintering to form the intermediate layer;

s5, preparing a preset powder coating: mixing the thermal barrier coating material with a binder to form coating slurry, then coating the coating slurry on the intermediate layer, and drying to obtain the preset powder coating;

s6, preparing a high-temperature heat barrier coating: and carrying out laser cladding on the preset powder coating to obtain a high-temperature heat-barrier coating on the intermediate layer.

2. The method for preparing the molybdenum alloy surface high-temperature heat-barrier coating according to claim 1, wherein the steps of S1, pretreatment of the molybdenum alloy plate are as follows: wherein the thickness of the molybdenum alloy plate is 3-10mm.

3. The method for preparing the molybdenum alloy surface high-temperature heat-barrier coating according to claim 1, wherein the step S2 is to prepare an intermediate layer material: the intermediate layer is made of zirconia powder and is subjected to ball milling; wherein the purity of the zirconia powder is not less than 99%; the ball milling rotating speed is 100-150rpm, the ball milling time is 10-15 hours, and the particle size of the zirconia powder particles after ball milling is 8-10 mu m.

4. The method for preparing the molybdenum alloy surface high-temperature heat barrier coating according to claim 1, wherein the step S3 is to prepare a thermal barrier coating material: the preparation process of the thermal barrier coating material comprises the following steps: according to mass fraction, 2.0-5.0wt% of Cr powder, 1.0-2.0wt% of Ti powder, 2.0-3.0wt% of Ni powder, 0.1-0.5wt% of Mn powder, 0.5-1.0wt% of B powder and the balance MoSi ₂ Mixing and ball milling the powder to obtain MoSi ₂ A powder-based mixed alloy powder; wherein: the ball milling rotating speed is 120-150rpm, and the ball milling time is 12-15 hours.

5. The method for preparing the molybdenum alloy surface high-temperature heat-barrier coating according to claim 4, wherein the step S3 is to prepare a thermal barrier coating material: the particle size of each powder after ball milling was as follows:

the purity of Cr powder is not lower than 97%, and the particle size of the Cr powder is 3-4 mu m;

the purity of Ti powder is not lower than 95%, and the particle size of the powder is 3-5 mu m;

the purity of Ni powder is not lower than 97%, and the particle size of the powder is 4-6 mu m;

the purity of Mn powder is not less than 98%, and the particle size of the powder is 2-3 mu m;

the purity of the powder B is not lower than 95%, and the particle size of the powder B is 2-3 mu m;

MoSi ₂ the purity of the powder is not less than 99%, and the particle size of the powder is 3-5 μm.

6. The method for preparing the molybdenum alloy surface high-temperature heat-barrier coating according to claim 1, wherein in the step S4, an intermediate layer is prepared: and coating the interlayer material on the surface of the pretreated molybdenum alloy plate, and then sintering to form an interlayer with the thickness of 0.1-0.5mm by adopting a spark plasma sintering method.

7. The method for preparing the molybdenum alloy surface high-temperature heat-barrier coating according to claim 6, wherein in the step S4, an intermediate layer is prepared: the technological parameters of the spark plasma sintering method are as follows: sintering temperature is 1800-2000 ℃, sintering pressure is 30-40MPa, and sintering time is 5-7 minutes.

8. The method for preparing the molybdenum alloy surface high-temperature heat-barrier coating according to claim 1, wherein the step S5 is to prepare a preset powder coating: mixing the thermal barrier coating material with a binder to form coating slurry, then coating the coating slurry on the intermediate layer, and drying to obtain the preset powder coating; wherein: the adhesive is acetone; the mass ratio of the thermal barrier coating material to the binder is 1: (0.6-1); the thickness of the preset powder coating is 1-2mm, and the powder coating is dried for 5-15 minutes at 110-130 ℃.

9. The method for preparing the molybdenum alloy surface high-temperature heat-barrier coating according to claim 1, wherein in the step S6, the high-temperature heat-barrier coating is prepared: carrying out laser cladding on the preset powder coating to obtain a 1-2mm thick high-temperature heat-barrier coating on the intermediate layer; wherein: the laser cladding is performed on YLS-4000 laser surface modification equipment, the laser process parameters are 20mm in height, 4.2mm in spot diameter, 30% in lap joint rate, 3000-3500W in laser power, 5-8mm/s in scanning speed and 10-20L/min in argon gas flow.