CN105177536A - Method for preparing micrometer-particle-contained high-temperature-oxidation-resistant composite coating on surface of niobium alloy - Google Patents

Abstract

The invention discloses a preparation method of a high-temperature oxidation-resistant composite coating containing micron particles on the surface of a niobium alloy. Firstly, the Ni-CeO ₂ coating is deposited on the substrate through the chemical composite plating process; then, the Al-rich infiltration layer is deposited on the coating through the embedding infiltration process to form a composite coating. The composite coating prepared by the invention is well combined with the substrate, the coating is uniform and compact, has good high-temperature oxidation resistance, can withstand oxidation at 1200 DEG C, prolongs the service life of the coating, and has a simple process.

Description

Preparation method of high temperature oxidation resistant composite coating containing micron particles on the surface of niobium alloy

technical field

The invention relates to the technical field of high-temperature protective coatings, in particular to a method for preparing a high-temperature oxidation-resistant composite coating containing micron particles on the surface of a niobium alloy.

Background technique

When aerospace, nuclear industry and gas turbines are working, the blades must withstand high temperatures of 1000°C to 1200°C. Nickel-based high temperature is limited by its own melting point (about 1400°C), and its service temperature limit is only 1100°C. Therefore, it is imperative to develop high-temperature structural materials with higher service temperatures. Metal niobium (Nb) has the advantages of high melting point, low density and high specific strength at high temperature, etc., but the oxidation resistance of niobium and niobium alloys is poor, and pure metal Nb will undergo catastrophic "powdering" oxidation at 600 °C. Oxidation belongs to a system with obvious cracks in the oxide layer. As the oxide layer thickens, the internal stress generated on the interface between the oxide and the metal will crack the oxide layer, followed by catastrophic oxidation. Therefore, improving the high temperature oxidation resistance of niobium alloy is the key to broaden its application.

The current target application temperature of niobium alloy is 1200°C. Alloying and surface coating are effective ways to improve the oxidation resistance of niobium alloys, but the addition of alloying elements must be controlled within a reasonable range, otherwise the mechanical properties of the alloy will be reduced; Coating a protective coating on the surface of the alloy can not only improve the high temperature oxidation resistance and corrosion resistance of the alloy, but also have good mechanical properties, so the surface coating is widely used. Niobium Alloy High-Temperature Oxidation-Resistant Materials and Method for Preparing High-Temperature Oxidation-Resistant Coatings" (Application No.: 201210237037.7); the coating prepared by this method effectively solves the problem of low-density niobium alloys at temperatures above 800°C, especially at temperatures around 1100°C. The problem of severe oxidation in the atmospheric environment; ② "Methods for preparing high-temperature oxidation-resistant coatings on niobium-tungsten alloys" (application number: 201110024937.9), this technology mainly uses cold spraying and laser cladding technology on niobium-tungsten alloys (Nb521) Prepare high-temperature anti-oxidation nanocomposite coatings on the surface; ③ "High-temperature anti-oxidation materials and high-temperature anti-oxidation coatings prepared therefrom" (application number: 200610137224.2), this technology is mainly by making high-temperature anti-oxidation materials into powder, adding other After the paint is mixed, it is applied to the substrate and then sintered to prepare the coating; ④ "Niobium Alloy High Temperature Oxidation Resistant Silicide Coating and Its Preparation Method" (application number: 200710192652.X), this technology is first passed on the surface of the niobium alloy substrate Vacuum sintering the particle size molybdenum layer, and then under the protection of argon, the coating is prepared by cladding siliconization. Although the coatings prepared by the above four patents have solved the problem of niobium alloy oxidation in high-temperature atmospheric environments, the coatings are mainly prepared by slurry method and spraying method, and the specific test results (such as phase analysis) after the coating is oxidized and shape characteristics, etc.) are not yet clear.

Contents of the invention

The technical problem to be solved by the present invention is to provide a niobium alloy with micro A method for preparing a high-temperature oxidation-resistant composite coating for particles.

The present invention adopts following technical scheme to solve the above-mentioned technical problem:

A method for preparing a high-temperature oxidation-resistant composite coating containing micron particles on the surface of a niobium alloy, comprising the following steps:

(1) Pretreatment: the base material was successively ultrasonically cleaned in acetone and absolute ethanol with a mass concentration of 99.9% respectively for 10 minutes, and dried;

(2) Coating pretreatment: the substrate is subjected to chemical degreasing, pickling, primary zinc dipping, zinc stripping, secondary zinc dipping and water washing in sequence;

(3) Particle activation: the CeO ₂ micron particles were soaked in alcohol with a mass concentration of 99.9% and activated in deionized water for 10 minutes each;

(4) Preparation of Ni-CeO ₂ coating: The formula of the plating solution is: nickel sulfate 25-35g/L, sodium hypophosphite 15-25g/L, trisodium citrate 15-20g/L, ammonium chloride 10-25g/L L, sodium acetate 15-25g/L; after preparing the plating solution according to the above formula, adjust the pH value of the plating solution to 8 with ammonia water, place the reaction in a magnetic stirrer during the process, and activate the activated CeO ₂ micron particles are added to the plating solution at 8-10g/L, the sample is suspended in the plating solution, and the reaction time is t=1h;

(5) Embedding aluminizing: prepare the infiltrating agent according to the following mass percentages: Al ₂ O ₃ powder 85-89%, Al powder 9-11%, NaF powder 2-4%, mix and grind; Put it into a crucible and embed the infiltrating agent, place the crucible in the quartz tube of a vacuum tube furnace, evacuate to 100-900mtorr, and keep it at a furnace temperature of 860-940°C for 3-4 hours; after the heat preservation is completed, cool it down to room temperature with the furnace , to obtain the composite coating.

The degreaser formula for chemical degreasing in the step (2) is: 25g/LNa ₃ PO ₄ 12H ₂ O, 30g/LNa ₂ CO ₃ , 10g/LNa ₂ SiO ₃ ; pickling uses mixed acid, the proportion The volume ratio of water and sulfuric acid solution is 1:1, and the mass concentration of sulfuric acid solution is 95-98%; the formula of zinc dipping solution used in one zinc dip is: 50g/LNaOH, 2g/LKNaC ₄ H ₄ O ₆ ·H ₂ O,5g/LZnO,2g/LFeCl ₃ 6H ₂ O,1g/LNaNO ₃ ; the zinc stripping solution used for stripping zinc is: water and nitric acid solution with a volume ratio of 1:1, and the mass concentration of nitric acid solution is 65-68% ; The second zinc dipping solution is the same as the primary zinc dipping solution; the water washing is distilled water washing.

The alcohol immersion in the step (3) is to add CeO ₂ micron particles into an alcohol solution with a mass concentration of 99.9% for immersion, and add 2g/L of nonionic surfactant OP-21 and then stir and soak for 10min until the alcohol solution is clarified , Pour off the alcohol solution and add deionized water to soak for 10 minutes.

In the step (5), the heating rate of the vacuum tube furnace is 10° C./min.

The beneficial effects of the present invention are:

1. The present invention adopts the chemical plating process and the embedding infiltration process to prepare the composite coating, which is well combined with the substrate, and the coating is uniform and compact.

2. The composite coating is to deposit a layer of Al-rich coating on the surface of the Ni-CeO ₂ coating. It is a new alloying method, which is different from other methods of directly adding Al, Ni, Ce and other elements to the Nb alloy.

3. Effectively prolong the service life of the coating. The surface of the coating is rich in Al and Ni, and the rare earth element Ce is added. The coating is mainly composed of AlNi phase, Al ₃ Nb phase and CeO ₂ phase, and a continuous and dense Al ₂ O ₃ film is formed in a high temperature environment, thereby delaying the degradation of the coating , showing good high temperature oxidation resistance.

4. Coatings with different compositions and thicknesses can be obtained by controlling the deposition parameters. The process is simple and repeatable, and is suitable for industrial production.

5. The composite coating can withstand long-term oxidation at 1200°C.

Description of drawings

Fig. 1 is the XRD spectrum of the composite coating of Example 1 of the present invention.

Fig. 2 is the surface morphology of the porous composite coating in Example 1 of the present invention.

Fig. 3 is the cross-sectional morphology of the infiltrated composite coating in Example 1 of the present invention.

Fig. 4 is the oxidation weight gain curve of the composite coating in Example 1 of the present invention oxidized at 1200°C for 20 hours.

Fig. 5 is the 20h XRD pattern of the composite coating in Example 1 of the present invention oxidized at 1200°C.

Fig. 6 is the cross-sectional morphology of the composite coating in Example 1 of the present invention oxidized at 1200°C for 20 hours. In the figure, 1. Al ₂ O ₃ film; 2. Composite coating; 3. Nb substrate.

Fig. 7 is the 20h XRD pattern of the composite coating in Example 2 of the present invention oxidized at 1000°C.

Figure 8 is the cross-sectional morphology of the composite coating in Example 2 of the present invention oxidized at 1000°C for 20 hours. In the figure, 1. Al ₂ O ₃ film; 2. Composite coating; 3. Nb substrate.

Figure 9 is the oxidation weight gain curve of the composite coatings of Examples 1 and 2 of the present invention oxidized at 1000°C for 20h. In the figure, (a) 860°C rich Al/Ni-P-CeO2/C103 coating (b) 940°C rich Al/Ni-P-CeO2/C103 coating (c) substrate.

Fig. 10 is the cross-sectional morphology of the composite coating in Example 3 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments and accompanying drawings, but this does not constitute a limitation to the protection scope of the claims of the present invention.

Example 1:

A method for preparing a high-temperature oxidation-resistant composite coating containing micron particles on the surface of a niobium alloy, comprising the following steps:

1. Pretreatment: The base material is niobium alloy, and the base material is ultrasonically cleaned in acetone and absolute ethanol with a mass concentration of 99.9% respectively for 10 minutes, and dried;

2. Coating pretreatment:

Substrates are pretreated in turn as follows:

Chemical degreasing, degreasing agent formula: 25g/LNa ₃ PO ₄ 12H ₂ O, 30g/LNa ₂ CO ₃ , 10g/LNa ₂ SiO ₃ ;

Pickling, mixed acid proportioning is: water: sulfuric acid volume ratio=1:1, wherein sulfuric acid mass concentration is 95%;

One-time zinc dipping, the formula of zinc dipping solution is: 50g/LNaOH, 2g/LKNaC ₄ H ₄ O ₆ H ₂ O, 5g/LZnO, 2g/LFeCl ₃ 6H ₂ O, 1g/LNaNO ₃ ;

Zinc stripping, zinc stripping solution is water: nitric acid volume ratio=1:1, wherein nitric acid mass concentration is 65%;

The second zinc dipping is the same as the primary zinc dipping solution;

Wash with distilled water;

3. Particle activation: soak CeO ₂ micron particles in an alcohol solution with a mass concentration of 99.9%, and add 2g/L OP-21 to stir and soak. After the alcohol solution is clarified, pour out the alcohol solution and add deionized water to soak. Solution and deionized water immersion activation treatment for 10 minutes each;

4. Preparation of Ni-CeO ₂ coating:

The formula of the plating solution is: nickel sulfate 25g/L, sodium hypophosphite 20g/L, trisodium citrate 18g/L, ammonium chloride 18g/L, sodium acetate 18g/L;

Adjust the pH value of the plating solution to 8 with ammonia water, add activated CeO ₂ micron particles into the plating solution at a plating temperature of 80°C at a rate of 10g/L, hang the sample in the plating solution for 1h, and prepare Ni-CeO ₂ coating, the process is placed in a magnetic stirrer to react;

5. Embedding aluminizing:

Prepare the penetrating agent according to the following mass percentages: Al ₂ O ₃ powder 87%, Al powder 10%, NaF powder 3%, mix and grind;

Put the sample containing the coating into the crucible and embed the infiltrant. The crucible is placed in the quartz tube of the vacuum tube furnace, vacuumed to 100mtorr, and aluminized in the vacuum tube furnace. The heating rate of the vacuum tube furnace is 10°C/min , the aluminizing temperature is 940°C, and the holding time is 4h. After the holding is completed, it is cooled to room temperature with the furnace to obtain a composite coating with a thickness of 40μm.

Example 2

1, pretreatment is the same as embodiment 1.

2. Coating pretreatment:

Substrates are pretreated in turn as follows:

Chemical degreasing is the same as in Example 1.

Pickling, mixed acid proportioning is: water: sulfuric acid volume ratio=1:1, wherein sulfuric acid concentration is 97%;

One-time galvanizing and two-time galvanizing are all the same as in Example 1.

Zinc stripping, zinc stripping solution is water: nitric acid volume ratio=1:1, wherein nitric acid mass concentration is 66%;

Wash with distilled water;

3. Particle activation: soak CeO ₂ micron particles in an alcohol solution with a mass concentration of 99.9%, and add 2g/L OP-21 to stir and soak. After the alcohol solution is clarified, pour out the alcohol solution and add deionized water to soak; Solution and deionized water immersion activation treatment for 10 minutes each.

4. Preparation of Ni-CeO ₂ coating:

Plating solution formula: nickel sulfate 28g/L, sodium hypophosphite 15g/L, trisodium citrate 15g/L, ammonium chloride 10g/L, sodium acetate 15g/L; adjust the pH value of the plating solution to 8 with ammonia water, At a plating temperature of 70°C, add activated CeO ₂ nanoparticles into the plating solution at 8 g/L, hang the sample in the plating solution for 1 hour, and prepare the Ni-CeO ₂ coating. The process is placed in a magnetic stirrer to react ;

5. Embedding aluminizing:

Prepare the penetrating agent according to the following mass percentages: Al ₂ O ₃ powder 85%, Al powder 11%, NaF powder 4%, mix and grind;

Put the sample containing the coating into the crucible and embed the infiltrant. The crucible is placed in the quartz tube of the vacuum tube furnace, vacuumed to 900mtorr, and aluminized in the vacuum tube furnace. The heating rate of the vacuum tube furnace is 10°C/min , the aluminizing temperature is 860°C, and the holding time is 3h. After the holding is completed, it is cooled to room temperature with the furnace to obtain a composite coating with a thickness of 20μm.

Example 3:

1, pretreatment is the same as embodiment 1.

2. Coating pretreatment:

The samples were pretreated sequentially as follows:

Chemical degreasing is the same as in Example 1.

Pickling, mixed acid proportioning is: water: sulfuric acid volume ratio=1:1, wherein sulfuric acid concentration is 98%;

One-time galvanizing and two-time galvanizing are all the same as in Example 1.

Zinc stripping, zinc stripping solution is water: nitric acid volume ratio=1:1, wherein nitric acid mass concentration is 68%;

3. Particle activation: soak CeO ₂ micron particles in an alcohol solution with a mass concentration of 99.9%, and add 2g/L OP-21 to stir and soak. After the alcohol solution is clarified, pour out the alcohol solution and add deionized water to soak; Solution and deionized water immersion activation treatment for 10 minutes each.

4. Preparation of Ni-CeO ₂ coating:

Plating solution formula: nickel sulfate 35g/L, sodium hypophosphite 25g/L, trisodium citrate 20g/L, ammonium chloride 25g/L, sodium acetate 25g/L;

Adjust the pH value of the plating solution to 8 with ammonia water, add activated CeO ₂ micron particles into the plating solution at a rate of 9 g/L at a plating temperature of 75 ° C, and hang the sample in the plating solution for 1 hour plating to prepare Ni-CeO ₂ coating, the process is placed in a magnetic stirrer to react;

5. Embedding aluminizing:

Prepare the penetrating agent according to the following mass percentages: Al ₂ O ₃ powder 89%, Al powder 9%, NaF powder 2%, mix and grind;

Put the sample containing the coating into the crucible and embed the infiltrant. The crucible is placed in the quartz tube of the vacuum tube furnace, vacuumed to 500mtorr, and aluminized in the vacuum tube furnace. The heating rate of the vacuum tube furnace is 10°C/min , the aluminizing temperature is 900°C, and the holding time is 4h. After the holding is completed, it is cooled to room temperature with the furnace to obtain a composite coating. The thickness of the composite coating is about 40 μm.

One, with the high-temperature anti-oxidation composite coating that embodiment 1 makes, utilize XRD diffraction to detect the phase structure of coating respectively, utilize scanning electron microscope (SEM) to observe the surface and cross-sectional morphology of coating, measurement result is shown in Fig. 1- Figure 7, the measurement results show that:

It can be seen from Figure 1 that the infiltrated composite coating is mainly composed of Al ₃ Nb, Al ₃ Ni, AlNi, and CeO ₂ phases, indicating that during the aluminizing process, the Al in the outer layer, the Ni element in the inner layer and the matrix all undergo obvious diffusion reactions. , thus forming Al-Ni, Al-Nb phases.

It can be seen from Figure 2 that the surface of the composite coating has a floc structure and contains micropores, without cracking and falling off, and is well combined with the matrix.

It can be seen from Figure 3 that the coating grows uniformly and densely, and is closely combined with the substrate.

It can be seen from Figure 4 that after oxidation at 1200°C for 20h, the weight gain of the sample containing the composite coating is only 2.7mg/cm ² after oxidation for 20h, which is much smaller than the weight gain of the substrate at 1000°C/20h in Figure 9.

It can be seen from Figure 5 that after oxidation at 1200°C for 20 h, the Al ₂ O ₃ phase was formed on the surface of the coated sample.

It can be seen from Figure 6 that after oxidation at 1200°C/20h, an oxide layer is formed on the outer layer of the coating. After a long time of high-temperature oxidation, holes appear in the outer layer of the coating, while the inner layer maintains good continuity and compactness. , the bond between the coating and the substrate is still tight.

It can be seen from Figure 9 that the weight gain of the niobium alloy substrate is 254.1mg/cm ² after oxidation at 1000°C for 20 hours, and the weight gain of the sample after plating and infiltration at 940°C for 20 hours is 2.2mg/cm ² , indicating that the composite coating contains The high-temperature oxidation resistance of the sample is good, which is 114 times higher than that of the matrix after calculation.

Two, the measurement result of embodiment 2 shows:

It can be seen from Figure 7 that after oxidation at 1000°C for 20 hours, the sample containing the composite coating mainly forms Al ₂ O ₃ phase.

It can be seen from Figure 8 that after oxidation at 1000°C for 20 hours, a uniform and dense Al ₂ O ₃ layer was formed on the surface of the sample that was first plated and then infiltrated with the composite coating. Al ₂ O ₃ layers, composite coatings, and substrates are well bonded with each other without falling off.

It can be seen from Figure 9 that the weight gain of the niobium alloy substrate is 254.0653 mg/cm ² after oxidation at 1000°C for 20 hours, and the weight gain of the composite coating sample after oxidization at 860°C for 20 hours is 3.6 mg/cm ² . The sample of the layer has good high temperature oxidation resistance, which is 70 times higher than that of the matrix after calculation.

Three, the measurement result of embodiment 3 shows:

It can be seen from Figure 10 that the composite coating is flat and continuous, and the coating is closely bonded to the niobium alloy substrate without holes or cracks.

Claims (4)

1. a method for preparing a niobium alloy surface containing a high-temperature oxidation-resistant composite coating of micron particles, characterized in that, comprising the following steps: (1) Pretreatment: the base material was successively ultrasonically cleaned in acetone and absolute ethanol with a mass concentration of 99.9% respectively for 10 minutes, and dried; (2) Coating pretreatment: the substrate is subjected to chemical degreasing, pickling, primary zinc dipping, zinc stripping, secondary zinc dipping and water washing in sequence; (3) Particle activation: the CeO ₂ micron particles were soaked in alcohol with a mass concentration of 99.9% and activated in deionized water for 10 minutes each; (4) Preparation of Ni-CeO ₂ coating: The formula of the plating solution is: nickel sulfate 25-35g/L, sodium hypophosphite 15-25g/L, trisodium citrate 15-20g/L, ammonium chloride 10-25g/L L, sodium acetate 15-25g/L; after preparing the plating solution according to the above formula, adjust the pH value of the plating solution to 8 with ammonia water, place the reaction in a magnetic stirrer during the process, and activate the activated CeO ₂ micron particles are added to the plating solution at 8-10g/L, the sample is suspended in the plating solution, and the reaction time is t=1h; (5) Embedding aluminizing: prepare the infiltrating agent according to the following mass percentages: Al ₂ O ₃ powder 85-89%, Al powder 9-11%, NaF powder 2-4%, mix and grind; Put it into a crucible and embed the infiltrating agent, place the crucible in the quartz tube of a vacuum tube furnace, evacuate to 100-900mtorr, and keep it at a furnace temperature of 860-940°C for 3-4 hours; after the heat preservation is completed, cool it down to room temperature with the furnace , to obtain the composite coating. 2. as described in claim 1, the preparation method of a kind of niobium alloy surface containing the anti-high temperature oxidation composite coating of micron particles, it is characterized in that, the degreasing agent formula of chemical degreasing in the described step (2) is: 25g /LNa ₃ PO ₄ ·12H ₂ O, 30g/LNa ₂ CO ₃ , 10g/LNa ₂ SiO ₃ ; pickling uses mixed acid, the ratio of water and sulfuric acid solution volume ratio is 1:1, and the mass concentration of sulfuric acid solution 95~98%; the formula of zinc dipping solution used in one-time zinc dipping is: 50g/LNaOH, 2g/LKNaC ₄ H ₄ O ₆ ·H ₂ O, 5g/LZnO, 2g/LFeCl ₃ ·6H ₂ O, 1g/LNaNO _3. The zinc stripping solution used for stripping zinc is: water and nitric acid solution with a volume ratio of 1:1, wherein the mass concentration of nitric acid solution is 65-68%; the second zinc dipping solution is the same as the primary zinc dipping solution; the water washing is distilled water washing. 3. as described in claim 1, the preparation method of a kind of niobium alloy surface containing the anti-high temperature oxidation composite coating of micron particle, it is characterized in that, the alcohol immersion of described step ( ₃ ) is that CeO2 micron particle is added mass concentration Soak in 99.9% alcohol solution, add 2g/L non-ionic surfactant OP-21, stir and soak for 10 minutes, and when the alcohol solution is clear, pour out the alcohol solution and add deionized water to soak for 10 minutes. 4. A method for preparing a high-temperature oxidation-resistant composite coating containing micron particles on the surface of a niobium alloy as claimed in claim 1, wherein the heating rate of the vacuum tube furnace in step (5) is 10° C./min.