CN112024818B - Ablation-resistant and ablation-resistant protective coating on surface of molybdenum metal core and preparation method - Google Patents
Ablation-resistant and ablation-resistant protective coating on surface of molybdenum metal core and preparation method Download PDFInfo
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- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical group [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 title claims abstract description 66
- 238000002679 ablation Methods 0.000 title claims abstract description 25
- 239000011253 protective coating Substances 0.000 title claims abstract description 24
- 238000002360 preparation method Methods 0.000 title abstract description 10
- 239000011248 coating agent Substances 0.000 claims abstract description 48
- 238000000576 coating method Methods 0.000 claims abstract description 48
- 230000003647 oxidation Effects 0.000 claims abstract description 29
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 29
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 26
- 238000011065 in-situ storage Methods 0.000 claims abstract description 25
- 239000002131 composite material Substances 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 21
- 239000011159 matrix material Substances 0.000 claims abstract description 18
- 230000008595 infiltration Effects 0.000 claims abstract description 15
- 238000001764 infiltration Methods 0.000 claims abstract description 15
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 10
- 239000011733 molybdenum Substances 0.000 claims abstract description 9
- UNQHSZOIUSRWHT-UHFFFAOYSA-N aluminum molybdenum Chemical compound [Al].[Mo] UNQHSZOIUSRWHT-UHFFFAOYSA-N 0.000 claims description 37
- 239000005078 molybdenum compound Substances 0.000 claims description 33
- 239000000463 material Substances 0.000 claims description 32
- 229910052593 corundum Inorganic materials 0.000 claims description 26
- 238000001816 cooling Methods 0.000 claims description 23
- 238000005269 aluminizing Methods 0.000 claims description 20
- 239000010431 corundum Substances 0.000 claims description 20
- 229910052573 porcelain Inorganic materials 0.000 claims description 20
- 239000000758 substrate Substances 0.000 claims description 18
- 239000000843 powder Substances 0.000 claims description 14
- 229910045601 alloy Inorganic materials 0.000 claims description 13
- 239000000956 alloy Substances 0.000 claims description 13
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 10
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 10
- 238000004140 cleaning Methods 0.000 claims description 10
- 238000001035 drying Methods 0.000 claims description 10
- 238000011049 filling Methods 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 8
- 238000010298 pulverizing process Methods 0.000 claims description 7
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 6
- 229910052786 argon Inorganic materials 0.000 claims description 5
- 238000002844 melting Methods 0.000 claims description 5
- 230000008018 melting Effects 0.000 claims description 5
- 238000007789 sealing Methods 0.000 claims description 5
- 230000003628 erosive effect Effects 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 238000005498 polishing Methods 0.000 claims 1
- 238000004321 preservation Methods 0.000 claims 1
- 229910052594 sapphire Inorganic materials 0.000 abstract description 12
- 230000008569 process Effects 0.000 abstract description 8
- 239000010953 base metal Substances 0.000 abstract description 3
- 229910000951 Aluminide Inorganic materials 0.000 abstract 5
- 229910001182 Mo alloy Inorganic materials 0.000 abstract 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 12
- 238000005266 casting Methods 0.000 description 9
- 238000005516 engineering process Methods 0.000 description 9
- 230000008859 change Effects 0.000 description 5
- 239000013078 crystal Substances 0.000 description 5
- 239000003870 refractory metal Substances 0.000 description 5
- 229910000601 superalloy Inorganic materials 0.000 description 5
- 238000009792 diffusion process Methods 0.000 description 4
- 229910010293 ceramic material Inorganic materials 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 238000005495 investment casting Methods 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910000765 intermetallic Inorganic materials 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 229910006415 θ-Al2O3 Inorganic materials 0.000 description 2
- 229910000858 La alloy Inorganic materials 0.000 description 1
- 229910008423 Si—B Inorganic materials 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000004445 quantitative analysis Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000010183 spectrum analysis Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- 239000012720 thermal barrier coating Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C3/00—Selection of compositions for coating the surfaces of moulds, cores, or patterns
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/10—Cores; Manufacture or installation of cores
- B22C9/101—Permanent cores
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
- C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
- C23C10/34—Embedding in a powder mixture, i.e. pack cementation
- C23C10/36—Embedding in a powder mixture, i.e. pack cementation only one element being diffused
- C23C10/48—Aluminising
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C12/00—Solid state diffusion of at least one non-metal element other than silicon and at least one metal element or silicon into metallic material surfaces
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/10—Oxidising
- C23C8/12—Oxidising using elemental oxygen or ozone
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
Abstract
The invention discloses an ablation-resistant and ablation-resistant protective coating on the surface of a molybdenum metal core and a preparation method thereof. Firstly, preparing an aluminide coating on a pure molybdenum or molybdenum alloy matrix through an embedding infiltration process, and then carrying out in-situ oxidation on the aluminide coating to prepare an oxide/aluminide composite coating: wherein the composite coating is made of alpha-Al2O3、Al8Mo3、AlMo3Three phases; the total thickness of the coating is 15-70 mu m; the outermost layer of the coating is continuous and compact alpha-Al2O3The layer can play a remarkable role in ablation resistance and ablation resistance protection on the molybdenum metal core; firm metallurgical bonding is formed between the alumina layer and the aluminide layer of the coating and between the aluminide layer and the base metal, and the coating can be effectively prevented from peeling off and falling off due to stress in the preparation and use processes.
Description
Technical Field
The invention relates to a molybdenum metal core surface protective coating and a preparation method thereof, in particular to a molybdenum metal core surface ablation-resistant and ablation-resistant protective coating and a preparation method thereof.
Background
With the continuous development of the aviation industry and the continuous progress of the aviation technology, the development of the aero-engine with the large thrust-weight ratio is competitively developed in all countries in the world. In the development process of the aircraft engine, increasing the temperature of the inlet of the turbine is the most effective method for increasing the thrust-weight ratio of the aircraft engine. The increase of the turbine inlet temperature depends on three key technologies, namely a high temperature resistant alloy technology represented by a high temperature alloy technology, a thermal barrier coating technology and a hollow turbine blade air cooling technology. Among them, the air cooling technology of the hollow turbine blade is developed from the early radial convection cooling technology to the composite cooling technology which is widely used at present. A typical cooling system for a composite cooling high-pressure turbine blade can increase the inlet temperature of the turbine by nearly 400 ℃ by comprehensively using three cooling modes of impingement cooling, convection cooling and air film cooling.
Air-cooled hollow turbine blades are all produced by precision investment casting techniques, in which the cooling channels are realized mainly by means of ceramic cores. The ceramic material has the defects of poor plasticity and light density, and casting defects such as warping, core leakage, core deviation, core breaking and the like are easy to occur in the casting process of the thin-wall and irregular-shaped core prepared from the ceramic material. If refractory metal materials (molybdenum, tungsten, tantalum, niobium, alloys thereof and the like) with higher high-temperature creep resistance, high-temperature plasticity and density are adopted to replace the traditional ceramic materials to manufacture cores with smaller sizes and more complex shapes, a finer and more complex cooling channel can be formed in the turbine blade on the premise of ensuring the casting yield, so that the air cooling efficiency of the blade is obviously improved, and the inlet temperature of the turbine is further improved.
The typical precision investment casting process comprises the procedures of wax pressing, mold assembling, slurry hanging, sanding, dewaxing, roasting, pouring, shelling, depoling, finishing and the like. The refractory metal is easy to have ablation failure and ablation failure in the roasting stage and the pouring stage in the precise investment casting process. Ablation failure refers to: during the firing stage, the refractory metals are exposed to oxygen in the furnace atmosphere at high temperatures and are highly susceptible to catastrophic oxidation, resulting in significant changes in the shape of the core or a significant reduction in the strength of the metal itself. The ablation failure means: during the pouring phase, the refractory metal comes into contact with the molten superalloy and chemically reacts with the superalloy, causing a significant change in the shape of the core and the formation of deleterious phases in the superalloy casting. Thus, to avoid ablation and erosion failures, protective coatings have been applied to the surface of refractory metal cores.
Disclosure of Invention
The invention aims to provide an aluminum oxide/aluminum molybdenum compound composite protective coating on the surface of a molybdenum metal core and a preparation method thereof.
The outermost layer of the protective coating is continuous and compact alpha-Al2O3And (3) a layer. The alumina has various crystal forms, and is relative to alumina (gamma-Al) with other crystal forms2O3、θ-Al2O3、к-Al2O3Etc.), alpha-Al2O3Has the advantages of low self-diffusion rate and impurity ion diffusion rate, thereby having better ablation resistance. alpha-Al relative to silica2O3The chemical stability is higher in the high-temperature alloy in a molten state, so that the high-temperature alloy has better anti-corrosion capability. And alpha-Al2O3Is a thermodynamic stable phase, and can not generate volume change and generate larger volume stress due to phase change at high temperature, so that an oxide layer is peeled off and falls off. In the presence of alpha-Al2O3The inner layer between the substrate and the substrate is an aluminum molybdenum compound layer made of Al8Mo3、AlMo3Two phases. Relative to other Al-Mo intermetallic compounds (Al)12Mo、Al5Mo、Al17Mo4、Al22Mo5Etc.), Al8Mo3And AlMo3The phase has a higher melting point, which prevents the inner layer of the coating from melting due to contact with molten superalloy liquid during use. Firm metallurgical bonding is formed between the aluminum oxide layer and the aluminum molybdenum compound layer of the composite coating, and between the aluminum molybdenum compound layer and the base metal, so that the coating can be effectively prevented from peeling off and falling off under the stress action in the preparation and use processes.
The total thickness of the composite protective coating is preferably 15-70 mu m.
As another aspect of the invention, the preparation method of the aluminum oxide/aluminum molybdenum compound composite coating on the surface of the molybdenum metal core is implemented according to the following steps:
the method comprises the following steps: pretreating a molybdenum metal core substrate:
(1) the molybdenum metal matrix is sequentially polished by using 240#, 400#, 600# and 800# sandpaper step by step.
(2) And ultrasonically cleaning the polished substrate with absolute ethyl alcohol for 10-20 min, and drying.
In the present invention, the molybdenum metal core base material is pure molybdenum or a molybdenum-based alloy (TZM alloy, Mo-Si-B alloy, Mo-La alloy, etc.).
Step two: preparing an embedding seepage material:
preparing embedding infiltration material, wherein the components of the embedding infiltration material comprise Al powder with the granularity of 100-800 meshes and the purity of not less than 99.9 percent and NH with the granularity of 50-100 meshes and the purity of not less than 99.5 percent4Cl powder and Al with the granularity of 100-500 meshes and the purity of not less than 99.85 percent2O3And (3) pulverizing. Preferably, every 100g of embedding infiltration material comprises 1-4 g of Al powder with the granularity of 100-800 meshes and the purity of not less than 99.9 percent and 1-2 g of NH with the granularity of 50-100 meshes and the purity of not less than 99.5 percent4Cl powder and 94-98 g of Al with the granularity of 100-500 meshes and the purity of not less than 99.85 percent2O3And (3) pulverizing.
Step three: embedding aluminizing:
(1) and (3) filling the embedded seeping material prepared in the step two to the bottom of the crucible, then placing the molybdenum metal core matrix pretreated in the step one in the middle of the crucible, filling the embedded seeping material around the molybdenum metal core matrix, covering the crucible with a cover and sealing the crucible.
(2) And (3) putting the sealed crucible into a high-temperature tubular resistance furnace, vacuumizing, and introducing argon until the pressure in the furnace is atmospheric pressure.
(3) Starting the resistance furnace, raising the temperature to 800-1000 ℃ at the rate of 5-10 ℃/min, and preserving the heat for 0.5-2 h to perform embedding aluminizing.
(4) And after the embedding aluminizing time is finished, closing the tubular resistance furnace, cooling the sealed crucible to room temperature along with the furnace, then opening a crucible cover, taking out the molybdenum metal core, cleaning the molybdenum metal core in absolute ethyl alcohol for 5-10 min, drying the molybdenum metal core by using cold air, and obtaining an aluminum-molybdenum compound coating on the surface of the molybdenum metal core.
Step four: in situ oxidation
(1) And (3) placing the molybdenum metal core with the aluminum molybdenum compound coating prepared in the step three in a corundum porcelain boat, heating the high-temperature box type resistance furnace to 1250-1350 ℃, opening the furnace door, placing the corundum porcelain boat in the furnace, closing the furnace door, preserving heat for 2-4 hours, and carrying out in-situ oxidation.
(2) And after the in-situ oxidation time is finished, opening the furnace door, taking out the corundum porcelain boat, cooling the corundum porcelain boat to room temperature in the air, and obtaining the aluminum oxide/aluminum molybdenum compound composite coating on the surface of the molybdenum metal core.
The lower aluminum powder content in the embedding infiltration material is beneficial to inhibiting low-melting-point aluminum molybdenum (Al)12Mo、Al5Mo、Al17Mo4、Al22Mo5Etc.). Moderate aluminizing temperature can maintain higher aluminizing efficiency and simultaneously reduce the formation of defects such as aluminized layer cracks and the like. The in-situ oxidation temperature of 1250-1350 ℃ can ensure that the alumina formed by oxidation is alpha-Al2O3And not other crystalline forms of alumina. The total thickness of the protective coating increases with increasing aluminum powder content, aluminizing temperature, aluminizing time, in-situ oxidation temperature and in-situ oxidation time in the embedded infiltrant. The embedding calorization components, the calorization temperature and the in-situ oxidation temperature are unchanged, and the total thickness of the protective coating can be adjusted by adjusting the calorization time and the in-situ oxidation time.
The invention has the beneficial effects that:
1. the outermost layer of the alumina/aluminum molybdenum compound composite coating prepared by the invention is continuous and compact alpha-Al2O3Layer of alumina having a plurality of crystal forms, relative to other crystal forms of alumina (gamma-Al)2O3、θ-Al2O3、к-Al2O3Etc.), alpha-Al2O3Has the advantages of low self-diffusion rate and impurity ion diffusion rate, thereby having better ablation resistance. alpha-Al relative to silica2O3The chemical stability is high in the high-temperature alloy in a molten state, so that the high-temperature alloy has better anti-corrosion capability. And alpha-Al2O3Is a thermodynamic stable phase, and can not generate volume change and generate larger volume stress due to phase change at high temperature, so that an oxide layer is peeled off and falls off. In the presence of alpha-Al2O3The inner layer between the substrate and the substrate is an aluminum molybdenum compound layer made of Al8Mo3、AlMo3Two phases. Relative to other Al-Mo intermetallic compounds (Al)12Mo、Al5Mo、Al17Mo4、Al22Mo5Etc.), Al8Mo3And AlMo3The phase has a higher melting point to prevent the coating from melting during use by contact with molten superalloy liquid.
2. The aluminum oxide layer and the aluminum molybdenum compound layer of the prepared aluminum oxide/aluminum molybdenum compound composite coating and the aluminum molybdenum compound layer and the base metal form firm metallurgical bonding, so that the coating can be effectively prevented from being stripped and falling off under the stress action in the preparation and use processes.
3. The alumina/aluminum molybdenum coating with different thicknesses can be obtained by controlling the embedding infiltration material components, the embedding time, the embedding temperature, the in-situ oxidation time and the in-situ oxidation temperature, the process is simple, the cost is lower, the repeatability is good, and the industrial implementation is convenient.
Drawings
FIG. 1 is an SEM cross-sectional view of an alumina/aluminum molybdenum compound composite coating prepared in example 1 of the invention.
FIG. 2 is an XRD spectrum of the alumina/aluminum molybdenum compound composite coating prepared in example 1 of the invention.
FIG. 3 is a SEM cross-sectional morphology view and an EDS surface scan of the alumina/aluminum molybdenum compound composite coating prepared in example 1 of the invention after a casting experiment.
FIG. 4 shows the EDS energy spectrum and quantitative analysis results of the layers after the casting test of the alumina/aluminum molybdenum compound composite coating prepared in example 1 of the present invention, wherein (a) corresponds to layer 1 in FIG. 3, (b) corresponds to layer 6 in FIG. 3, (c) corresponds to layer 7 in FIG. 3, (d) corresponds to layer 3 in FIG. 3, and (e) corresponds to layer 5 in FIG. 3.
Reference numerals: 1-Al2O3Layer, 2-Al8Mo3Layer, 3-AlMo3Layer, 4-AlMo3Particle, 5-matrix, 6-residual Al after casting8Mo3Layer, 7-newly formed internal oxide layer of alumina after casting.
Detailed Description
The invention is further illustrated by the following examples.
Example 1
A method for preparing a protective coating on the surface of a molybdenum metal core, wherein a substrate is pure molybdenum, comprises the following steps:
the method comprises the following steps: pretreating a molybdenum metal core substrate:
(1) the molybdenum metal matrix is sequentially polished by using 240#, 400#, 600# and 800# sandpaper step by step.
(2) And ultrasonically cleaning the polished substrate with absolute ethyl alcohol for 10min, and drying.
Step two: preparing an embedding seepage material:
preparing embedding infiltration material, wherein each 100g of the embedding infiltration material comprises 2g of Al powder with the granularity of 500 meshes and the purity of not less than 99.9 percent, and 2g of NH with the granularity of 100 meshes and the purity of not less than 99.5 percent4Cl powder and Al with the rest granularity of 300 meshes and the purity of not less than 99.85 percent2O3And (3) pulverizing.
Step three: embedding aluminizing:
(1) and (3) filling the embedded seeping material prepared in the step two to the bottom of the crucible, then placing the molybdenum metal core matrix pretreated in the step one in the middle of the crucible, filling the embedded seeping material around the molybdenum metal core matrix, covering the crucible with a cover and sealing the crucible.
(2) And (3) putting the sealed crucible into a high-temperature tubular resistance furnace, vacuumizing, and introducing argon until the pressure in the furnace is atmospheric pressure.
(3) Starting the resistance furnace, raising the temperature to 900 ℃ at the heating rate of 6 ℃/min, preserving the heat for 1h, and carrying out embedding aluminizing.
(4) And after the embedding aluminizing time is finished, closing the tubular resistance furnace, cooling the sealed crucible to room temperature along with the furnace, then opening a crucible cover, taking out the sample, cleaning the sample in absolute ethyl alcohol for 5min, drying the sample by using cold air, and obtaining an aluminum-molybdenum compound coating on the surface of the molybdenum metal core.
Step four: in-situ oxidation:
(1) and (3) placing the sample prepared in the third step into a corundum porcelain boat, heating the sample to 1300 ℃ in a high-temperature box type resistance furnace, opening a furnace door, placing the corundum porcelain boat into the furnace, closing the furnace door, preserving heat for 2 hours, and carrying out in-situ oxidation.
(2) And after the in-situ oxidation time is finished, opening the furnace door, taking out the corundum porcelain boat, cooling the corundum porcelain boat to room temperature in the air, and obtaining the aluminum oxide/aluminum molybdenum compound composite coating on the surface of the molybdenum metal core.
The total thickness of the coating obtained in example 1 was 36 μm.
Example 2
A method for preparing a protective coating on the surface of a molybdenum metal core, wherein a substrate is pure molybdenum, comprises the following steps:
the method comprises the following steps: pretreating a molybdenum metal core substrate:
(1) the molybdenum metal matrix is sequentially polished by using 240#, 400#, 600# and 800# sandpaper step by step.
(2) And ultrasonically cleaning the polished substrate with absolute ethyl alcohol for 10min, and drying.
Step two: preparing an embedding seepage material:
preparing embedding infiltration material, wherein each 100g of the embedding infiltration material comprises 4g of Al powder with the granularity of 500 meshes and the purity of not less than 99.9 percent and 2g of NH with the granularity of 100 meshes and the purity of not less than 99.5 percent4Cl powder and Al with the rest granularity of 300 meshes and the purity of not less than 99.85 percent2O3And (3) pulverizing.
Step three: embedding aluminizing:
(1) and (3) filling the embedded seeping material prepared in the step two to the bottom of the crucible, then placing the molybdenum metal core matrix pretreated in the step one in the middle of the crucible, filling the embedded seeping material around the molybdenum metal core matrix, covering the crucible with a cover and sealing the crucible.
(2) And (3) putting the sealed crucible into a high-temperature tubular resistance furnace, vacuumizing, and introducing argon until the pressure in the furnace is atmospheric pressure.
(3) Starting the resistance furnace, raising the temperature to 1000 ℃ at the heating rate of 6 ℃/min, and preserving the heat for 2h to carry out embedding aluminizing.
(4) And after the embedding aluminizing time is finished, closing the tubular resistance furnace, cooling the sealed crucible to room temperature along with the furnace, then opening a crucible cover, taking out the sample, cleaning the sample in absolute ethyl alcohol for 5min, drying the sample by using cold air, and obtaining an aluminum-molybdenum compound coating on the surface of the molybdenum metal core.
Step four: in-situ oxidation:
(1) and (3) placing the sample prepared in the third step into a corundum porcelain boat, heating the sample to 1350 ℃ in a high-temperature box type resistance furnace, opening a furnace door, placing the corundum porcelain boat into the furnace, closing the furnace door, preserving heat for 4 hours, and carrying out in-situ oxidation.
(2) And after the in-situ oxidation time is finished, opening the furnace door, taking out the corundum porcelain boat, cooling the corundum porcelain boat to room temperature in the air, and obtaining the aluminum oxide/aluminum molybdenum compound composite coating on the surface of the molybdenum metal core.
The total thickness of the coating obtained in example 2 was 67 μm.
Example 3
A method for preparing a protective coating on the surface of a molybdenum metal core, wherein a substrate is pure molybdenum, comprises the following steps:
the method comprises the following steps: pretreating a molybdenum metal core substrate:
(1) the molybdenum metal matrix is sequentially polished by using 240#, 400#, 600# and 800# sandpaper step by step.
(2) And ultrasonically cleaning the polished substrate with absolute ethyl alcohol for 10min, and drying.
Step two: preparing an embedding seepage material:
preparing embedding infiltration material, wherein each 100g of the embedding infiltration material comprises 1g of Al powder with the granularity of 500 meshes and the purity of not less than 99.9 percent and 1g of NH with the granularity of 100 meshes and the purity of not less than 99.5 percent4Cl powder and Al with the rest granularity of 300 meshes and the purity of not less than 99.85 percent2O3And (3) pulverizing.
Step three: embedding aluminizing:
(1) and (3) filling the embedded seeping material prepared in the step two to the bottom of the crucible, then placing the molybdenum metal core matrix pretreated in the step one in the middle of the crucible, filling the embedded seeping material around the molybdenum metal core matrix, covering the crucible with a cover and sealing the crucible.
(2) And (3) putting the sealed crucible into a high-temperature tubular resistance furnace, vacuumizing, and introducing argon until the pressure in the furnace is atmospheric pressure.
(3) Starting the resistance furnace, raising the temperature to 800 ℃ at the heating rate of 6 ℃/min, preserving the heat for 0.5h, and carrying out embedding aluminizing.
(4) And after the embedding aluminizing time is finished, closing the tubular resistance furnace, cooling the sealed crucible to room temperature along with the furnace, then opening a crucible cover, taking out the sample, cleaning the sample in absolute ethyl alcohol for 5min, drying the sample by using cold air, and obtaining an aluminum-molybdenum compound coating on the surface of the molybdenum metal core.
Step four: in-situ oxidation:
(1) and (3) placing the sample prepared in the third step into a corundum porcelain boat, heating the sample to 1250 ℃ in a high-temperature box type resistance furnace, opening a furnace door, placing the corundum porcelain boat into the furnace, closing the furnace door, preserving heat for 2 hours, and carrying out in-situ oxidation.
(2) And after the in-situ oxidation time is finished, opening the furnace door, taking out the corundum porcelain boat, cooling the corundum porcelain boat to room temperature in the air, and obtaining the aluminum oxide/aluminum molybdenum compound composite coating on the surface of the molybdenum metal core.
The total thickness of the coating obtained in example 3 was 15 μm.
The method comprises the steps of observing the cross section morphology of a coating by using a Scanning Electron Microscope (SEM), detecting the phase structure of the coating by using X-ray diffraction (XRD), detecting the distribution of elements contained in the coating by using an X-ray energy spectrometer (EDS), carrying out a pouring experiment on a sheet-shaped molybdenum metal core with the surface covered with an aluminum oxide/aluminum molybdenum compound composite protective coating by using DZ40M high-temperature alloy, and observing the cross section morphology of the poured coating and the distribution of the elements contained in the coating so as to verify the ablation resistance and the ablation resistance of the coating.
As shown in FIG. 1, the alumina/aluminum molybdenum coating prepared in example 1 is continuous, dense and made of Al2O3Layer of Al8Mo3Layer of AlMo3Layer and distribution in Al2O3Layer and Al8Mo3Small amount of AlMo between layers3And (4) particle composition.
As shown in FIG. 2, the crystal form of alumina in the alumina/aluminum molybdenum coating prepared in example 1 is alpha-Al2O3The aluminum molybdenum compound layer is made of Al8Mo3Phase and AlMo3Phase composition.
As shown in fig. 3 and 4, the aluminum oxide layer of the aluminum oxide/aluminum molybdenum compound composite coating prepared in example 1 is kept continuous and complete after casting experiments, the coating contains three elements of Al, Mo and O, and no phenomenon that elements (Co, Ni, Cr, W and the like) contained in the high-temperature alloy solution invade into the composite coating and the substrate is found, which indicates that the composite coating plays a significant role in protection.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or simple substitutions which are not thought of through the inventive work should be included in the scope of the present invention.
Claims (5)
1. The surface ablation-resistant and melting-resistant protective coating of the molybdenum metal core is characterized in that the base material of the protective coating is the molybdenum metal core, the protective coating comprises an alpha-alumina outer layer and an aluminum molybdenum compound inner layer which are continuous, metallurgical bonding is formed between the alpha-alumina outer layer and the aluminum molybdenum compound layer and between the aluminum molybdenum compound inner layer and the base body, and the aluminum molybdenum compound inner layer is formed by Al8Mo3And AlMo3Two phases are formed.
2. The molybdenum metal core surface ablation-resistant erosion-resistant protective coating of claim 1, wherein the molybdenum metal core matrix material is one of pure molybdenum or a molybdenum-based alloy.
3. The molybdenum metal core surface ablation and erosion resistant protective coating of claim 1 or 2, wherein the total thickness of the protective coating is 15-70 μm.
4. A method of making an ablation-resistant and erosion-resistant protective coating for the surface of a molybdenum metal core as claimed in any one of claims 1 to 3, comprising the steps of:
the method comprises the following steps: pretreating a molybdenum metal core substrate:
(1) sequentially polishing a molybdenum metal matrix by using 240#, 400#, 600# and 800# sandpaper step by step;
(2) ultrasonically cleaning the polished substrate for 10-20 min by using absolute ethyl alcohol, and drying;
step two: preparing an embedding seepage material:
preparing an embedding infiltration material, wherein the embedding infiltration material comprises the following components: al powder with granularity of 100-800 meshes and purity of not less than 99.9 percent, and NH with granularity of 50-100 meshes and purity of not less than 99.5 percent4Cl powder and Al with the granularity of 100-500 meshes and the purity of not less than 99.85 percent2O3Pulverizing; the embedding infiltration material comprises 1-4% of Al powder and 1-2% of NH by mass4Cl powder and 94-98% of Al2O3Pulverizing;
step three: embedding aluminizing:
(1) filling the embedding seeping material prepared in the step two to the bottom of the crucible, then placing the molybdenum metal core matrix pretreated in the step one in the middle of the crucible, filling the embedding seeping material around the matrix, and covering the crucible with a cover for sealing;
(2) placing the sealed crucible into a high-temperature tubular resistance furnace, vacuumizing, and introducing argon until the pressure in the furnace is atmospheric pressure;
(3) starting the resistance furnace, raising the temperature at a rate of 5-10 ℃/min to an embedding temperature, preserving the heat, and carrying out embedding aluminizing, wherein the embedding temperature is 800-1000 ℃, and the preserving time is 0.5-2 h;
(4) closing the tubular resistance furnace after the embedding aluminizing time is finished, cooling the sealed crucible to room temperature along with the furnace, then opening a crucible cover, taking out the molybdenum metal core, cleaning the molybdenum metal core in absolute ethyl alcohol for 5-10 min, and drying the molybdenum metal core by cold air to obtain an aluminum-molybdenum compound coating on the surface of the molybdenum metal core;
step four: in-situ oxidation:
(1) placing the molybdenum metal core with the aluminum molybdenum compound coating prepared in the third step into a corundum porcelain boat, heating the high-temperature box type resistance furnace to an oxidation temperature, opening a furnace door, placing the corundum porcelain boat into the furnace, closing the furnace door, preserving heat, and carrying out in-situ oxidation, wherein the oxidation temperature is 1250-1350 ℃, and the heat preservation time is 2-4 hours;
(2) and after the in-situ oxidation time is finished, opening the furnace door, taking out the corundum porcelain boat, cooling the corundum porcelain boat to room temperature in the air, and obtaining the alpha-alumina/aluminum molybdenum compound composite coating on the surface of the molybdenum metal core.
5. The method for preparing the ablation-resistant and ablation-resistant protective coating on the surface of the molybdenum metal core according to claim 4, wherein the protective coatings with different thicknesses are obtained by controlling the embedding and infiltrating components, the embedding and aluminizing time, the embedding temperature, the in-situ oxidation time and the in-situ oxidation temperature.
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