A high-boron iron-chromium-aluminum alloy porous material and preparation method thereof

Abstract

The present invention belongs to the field of alloy materials, and in particular relates to a high-boron iron-chromium-aluminum alloy porous material and a preparation method thereof. The method of the present invention comprises: 1) taking metal powder and / or alloy powder containing iron, chromium and aluminum and mixing them evenly with boron-containing powder to obtain a mixed powder; 2) granulating the mixed powder and pressing it into a blank; 3) sintering the blank to obtain the high-boron iron-chromium-aluminum alloy porous material. The present invention achieves high-temperature self-repairing protection of metal porous materials promoted by boron components by adding a relatively high boron element and a certain content of auxiliary elements such as yttrium and zirconium to the alloy. The obtained high-boron iron-chromium-aluminum alloy porous material with high-temperature self-repairing protection performance has broad application prospects and can be widely used in the fields of high-temperature filtration, catalyst carriers, etc.

Description

Technical Field

[0001] The present invention belongs to the field of alloy materials, and in particular relates to a high-boron iron-chromium-aluminum alloy porous material and a preparation method thereof. Background Art

[0002] Porous metal materials have good mechanical properties, machinability, temperature resistance, and excellent heat and mass transfer characteristics. As key high-temperature filter materials or catalyst carriers, they have demonstrated unique technical advantages and broad application prospects in the high-temperature production and utilization of many clean energy sources, such as blast furnace gas, biomass gas purification, chemical synthesis gas processes such as steam methane reforming, and solid oxide fuel cells. At present, porous metal materials have replaced ceramic porous filter materials and catalyst carriers in many medium and low temperature working conditions, but the stable service of materials in high temperature conditions above 700°C still faces severe challenges. Improving the high-temperature performance of porous metal materials is a research hotspot and key application technology demand in the fields of high-temperature filtration and high-temperature catalytic reactions at home and abroad.

[0003] However, during high-temperature service, porous metal materials are frequently subjected to thermal and mechanical shocks, and the oxide film is prone to cracking and peeling. In particular, the high specific surface area of ​​porous metal materials accelerates the consumption of film-forming elements and the porous skeleton with an extremely small curvature radius, which easily aggravates the shedding of the oxide film. When the local oxide film protection fails, the highly exposed high-angle grain boundaries in the porous metal material will become channels for atoms such as oxygen (O), sulfur (S), and carbon (C) to diffuse into the alloy matrix, thereby causing grain boundary oxidation or intergranular corrosion, resulting in a continuous decline in mechanical properties. Traditional material design ideas mostly use alloy design to improve the protective performance and anti-stripping ability of the oxide film, and rarely design alloy composition and organization based on the characteristics of porous materials. For porous materials, in addition to improving the basic performance of the alloy, designing a real-time repair mechanism for oxide film defects is a new high-temperature protection path.

[0004] In high-temperature protection, boron-containing components such as B, B4C, ZrB2, and borosilicate glass are often introduced into ceramic-based composites and high-temperature protective coatings to give the materials good high-temperature oxidation self-healing properties. Boron or boride, as self-healing components, has excellent high-temperature stability when it does not react with the environmental oxidizing medium; however, in a high-temperature oxidizing environment, it can react with O2, H2O, etc. to rapidly oxidize to form low-melting-point boron oxide (B2O3) glass and expand in volume. The viscous flow of B2O3 glass seals the pores and cracks in the protective layer, thereby achieving rapid repair. Introducing the "self-healing" protection mechanism of boron into the high-temperature protection of FeCrAl porous materials, through the oxidation of boron and the use of molten B2O3 to flow and fill the oxide film and grain boundary microcracks, is expected to significantly improve the high-temperature protection problems caused by the structural characteristics of porous metal materials. Summary of the Invention

[0005] In order to solve the problem that metal porous materials are frequently subjected to thermal and mechanical shocks during high-temperature service, and the oxide film is prone to cracking and peeling, the present invention provides a high-boron iron-chromium-aluminum alloy porous material and a preparation method of the alloy porous material.

[0006] The main objectives of the present invention are:

[0007] 1. To achieve the preparation of a porous alloy material with self-repairing and protective properties;

[0008] 2. Ensure that the prepared porous alloy material has excellent self-healing ability and good thermal stability under high temperature conditions; 3. Ensure that the material has good mechanical properties.

[0009] To achieve the above objectives, the present invention adopts the following technical solutions.

[0010] A method for preparing a high-boron iron-chromium-aluminum alloy porous material.

[0011] The method comprises:

[0012] 1) mixing metal powder containing iron, chromium and aluminum and / or iron-chromium-aluminum alloy powder with boron-containing powder to obtain a mixed powder;

[0013] 2) granulating the mixed powder and pressing it into embryos;

[0014] 3) The embryo body is subjected to temperature-controlled sintering to obtain the high-boron iron-chromium-aluminum alloy porous material.

[0015] The present invention uses iron-chromium-aluminum as the alloy substrate. Firstly, the common iron-chromium-aluminum alloy has a certain weak self-repair ability. Secondly, the iron-chromium-aluminum porous material has excellent corrosion resistance and mechanical properties. Under high-temperature corrosive conditions, the alloy can effectively prevent corrosive gases from corroding and damaging the substrate.

[0016] However, the repair process of the oxide film on the surface of common iron-chromium-aluminum alloys after local failure mainly depends on the diffusion and oxidation of aluminum elements, which is actually the secondary growth of aluminum oxide film. However, the secondary growth of aluminum oxide film has certain defects in achieving self-repair and protection. For example, under high temperature conditions (≥1000℃), the growth trend of aluminum oxide film is better, and it can achieve rapid self-repair and protection without the need for specific oxygen partial pressure conditions. However, below 1000℃, aluminum oxide is mainly composed of metastable γ-Al2O3 and θ-Al2O3, and it takes a certain amount of time to transform into stable α-Al2O3. Therefore, its timeliness has significant defects, and the protective performance formed is limited and easily damaged by secondary damage.

[0017] In the technical solution of the present invention, boron is also introduced. Boron has a small atomic radius and a fast diffusion rate. It is easily preferentially oxidized at high temperatures to achieve protection. Boron can produce significant positive effects in ceramic-based composites and high-temperature protective coatings. This is because boron and some specific borides themselves can serve as self-repairing components in iron-chromium-aluminum alloys. Unlike other alloy systems, in other conventional alloy systems, boron strengthens the alloy by diffusion doping and alloying with alloying elements. However, for the technical solution of the present invention, it independently forms a self-repairing unit. It is not based on the diffusion of alloying. Instead, after the aluminum oxide film structure of the alloy material's protective layer is destroyed, the oxidizing components in the rain environment medium, such as oxygen and water, react rapidly and oxidize to form boron oxide (B2O3) in a high-temperature oxidizing environment. After the boron oxide is formed, it expands in volume, and the boron oxide formed has glass viscosity, which can flow into the damaged protective layer pores and cracks, thereby achieving rapid repair, improving the self-repair timeliness of the alloy system of the present invention, and achieving rapid self-repair.

[0018] As a preference,

[0019] In the metal powder and / or alloy powder of step 1):

[0020] The Cr content is 10-20wt%, the Al content is 5-25wt%, and the balance is Fe;

[0021] The mesh size of the metal powder and / or alloy powder is 200 to 500 meshes.

[0022] The technical solution of the present invention allows for adaptive adjustment of the ratio of each element in the iron-chromium-aluminum alloy system within the aforementioned range, achieving optimal production results. The relative content of aluminum and chromium, particularly important to control, is crucial. Chromium is crucial for providing the alloy's fundamental antioxidant properties, while aluminum is the primary component of the protective layer. As the chromium content increases, the aluminum content also needs to be adjusted accordingly.

[0023] As a preference,

[0024] In step 1), the boron-containing powder is elemental boron and / or ferroboron and / or boron-yttrium composite powder and / or boron-zirconium composite powder.

[0025] Among them, common boron-yttrium composite powders include yttrium tetraboride, while common boron-zirconium composite powders include zirconium diboride, etc., which can produce similar preparation effects.

[0026] The present invention optimally uses boron yttrium compounds, and boron yttrium composite powders and / or boron zirconium composite powders. This is because the addition of rare earth elements will change the position of the boron element self-repairing unit in the alloy system, and have a certain impact on its effect. For example, the use of yttrium tetraboride can further make boron evenly dispersed in the surface layer of the alloy system. For the iron-chromium-aluminum alloy of the present invention, it can further improve its self-repairing timeliness. The principle is that the rare earth element yttrium, as an alloying element with a large atomic radius, can effectively improve the wettability between the boron-rich liquid phase and the porous material skeleton matrix during the sintering process, thereby promoting the boron element to be better and more evenly distributed on the surface of the porous skeleton, creating conditions for constructing a boron-rich layer with a self-repairing effect.

[0027] Therefore, in order to ensure that the surface boron-rich layer is well constructed, a certain amount of elements with large atomic radius, such as yttrium and zirconium, is added on the basis of the introduction of boron element. The addition amount is 0.2 to 1.0 wt% of the mass of the metal powder and / or alloy powder. The purpose is to regulate the distribution of the boron-rich liquid phase on the surface of the porous skeleton during the sintering process and improve the wettability. In order to ensure the effectiveness of the introduction of elements such as yttrium and zirconium, they can be dissolved in the liquid phase of the aluminum alloy. The aluminum alloy containing elements such as yttrium and zirconium can be atomized to obtain the required raw aluminum powder containing elements such as yttrium and zirconium. For the overall raw materials, elements such as yttrium and zirconium are highly active and have low content, and are easily oxidized and lost during the sintering process. Introducing them in the form of prefabricated aluminum alloy powder can maximize the activity of yttrium and zirconium. Alternatively, it can be converted into a composite powder by boronization. Boron-yttrium composite powder and boron-zirconium composite powder are both industrial raw materials that can be purchased directly. Yttrium and zirconium have more stable chemical properties and can also retain the chemical activity of yttrium and zirconium to the greatest extent. At the same time, compared with other rare earth elements, boron and yttrium themselves also have good synergistic effects with boron elements, which can produce a direct and effective strengthening effect.

[0028] In addition, to ensure a good self-repairing effect, boron or boride is added to the material so that the boron addition amount of the material is greater than 0.5wt% of the mass of the metal powder and / or alloy powder.

[0029] As a preference,

[0030] The process of mixing uniformly in step 1) is as follows:

[0031] Add ball milling balls for ball milling, with a ball-to-material mass ratio of (2-4):1, and control the ball milling speed at 40-60 r / min;

[0032] Inert gas is used for protection during the ball milling process.

[0033] Mixing the boron or boride component with the main alloy powder, followed by forming and reaction synthesis, can solve the difficult problems of melting and forming high-boron alloy powders. The mixing process ensures that the boron or boride powder and the alloy powder are evenly mixed in the powder, ensuring the compositional uniformity of the prepared high-boron iron-chromium-aluminum alloy.

[0034] As a preference,

[0035] Step 2) the granulation process is:

[0036] The mixed powder and the binder are mixed evenly, stirred until they become a paste, and dried and sieved under protective atmosphere or vacuum conditions.

[0037] Adhesive granulation is used to form relatively large particles, ensuring that the mesh size of the mixed powder is 30 to 100 meshes, which can ensure the uniformity of the ingredients and avoid the problem of poor preparation and molding effect caused by excessive powder particle size.

[0038] As a preference,

[0039] The binder is an ethanol solution of stearic acid;

[0040] The mass ratio of stearic acid to ethanol in the stearic acid ethanol solution is (0.05-0.2):1;

[0041] The mass ratio of the stearic acid to the mixed powder is (0.01-0.04):1.

[0042] Stearic acid is a solid at room temperature and must be dissolved in ethanol before being added to the powder to achieve a uniform distribution. The binder's function is to enhance the powder's formability and ensure that the material maintains certain mechanical properties after being pressed into a preform.

[0043] As a preference,

[0044] During step 2), the pressing pressure is 100-400 MPa.

[0045] Selecting the appropriate pressure to form the powder ensures that the material has relatively high porosity and high mechanical properties after sintering.

[0046] As a preference,

[0047] In step 3), the sintering temperature is 1100-1300°C.

[0048] For the present invention, the final sintering temperature should be controlled at 1100-1300℃, but in the actual sintering process, multi-stage temperature rising sintering should be carried out. Specifically, there should be a low-temperature sintering at 120-180℃ for 10-20min to remove water vapor and other adsorbed gases in the sample and sintering equipment; then, it should be sintered at 850-950℃ for 30-120min. At this temperature, the boron-rich liquid phase can be fully dispersed and homogenized as a whole under the action of capillary action and chemical potential, while further promoting the migration and dispersion of boron with the metastable structure in the alloy system to construct a surface boron-rich layer; finally, it should be sintered at a high temperature of 1100-1300℃ for 1.5-2.5h to achieve full dispersion and fixation of boron in the surface layer of the alloy, forming a good fast-response self-repairing function. After the sintering is completed, it should be cooled rapidly from the high temperature, with a cooling rate of not less than 20℃ / min. The high cooling rate is expected to further ensure the uniform distribution of the secondary boron layer. At the same time, the porous alloy composition obtained by the above sintering method can ensure uniform and rich pore structure under the coordination of low-temperature sintering and high-temperature sintering, and ensure that the alloy has good mechanical properties.

[0049] As a preference,

[0050] Step 3) The sintering process is carried out under vacuum conditions.

[0051] Using vacuum sintering can ensure that the material is not severely oxidized during high-temperature sintering.

[0052] A high-boron iron-chromium-aluminum alloy porous material.

[0053] The high-boron iron-chromium-aluminum alloy porous material with high-temperature self-repairing protection performance prepared by the present invention has good mechanical properties and high-temperature stability, and can be used in the fields of high-temperature filtration, catalyst carrier, etc.

[0054] The beneficial effects of the present invention are:

[0055] The present invention achieves high-temperature self-repair protection of metal porous materials promoted by the boron component by adding a relatively high content of boron and a certain content of auxiliary elements such as yttrium and zirconium to the alloy. The obtained high-boron iron-chromium-aluminum alloy porous material with high-temperature self-repair protection has broad application prospects and can be widely used in fields such as high-temperature filtration and catalyst carriers.

[0056] In the high-boron iron-chromium-aluminum alloy porous material with high-temperature self-healing protective performance, in addition to the boron partially dissolved in the matrix, the rest of the boron-rich phase is evenly and continuously distributed on the surface of the porous skeleton, especially in the surface layer of the alloy. The boron content on the surface of the boron-rich layer is as high as 6-9wt.%, which becomes a "boron trap" for regulating boron distribution and provides the "boron source" required for high-temperature self-healing.

[0057] The sample obtained from the high-boron iron-chromium-aluminum alloy porous material with high-temperature self-repairing protective performance prepared by the method of the present invention has a good and uniform pore structure, high mechanical properties and high-temperature stability, and has a longer service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 Schematic diagram of the self-repair of high-boron iron-chromium-aluminum alloy porous material with high-temperature self-repair protection performance;

[0059] Figure 2 The metallographic characterization results of the sample prepared in Example 1 of the present invention are as follows;

[0060] Figure 3 This is the surface element distribution characterization result of the sample prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0061] The present invention is further described in detail below with reference to specific embodiments and the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only a portion of the embodiments of the present invention, rather than all of the embodiments. Therefore, all other embodiments derived by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0062] Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art; unless otherwise specified, the methods used in the examples of the present invention are all methods known to those skilled in the art.

[0063] Unless otherwise specified, the powder materials used in the embodiments of the present invention are all 200 mesh powders.

[0064] Example 1

[0065] A high-boron iron-chromium-aluminum alloy porous material, the preparation process of which is as follows Figure 1 As shown,

[0066] The specific process includes:

[0067] 1) 71 g of iron powder, 14 g of chromium powder, and 15 g of aluminum powder were mixed with 0.5 g of boron powder, and ball milling was performed with a ball-to-material mass ratio of 2:1. The ball milling speed was controlled at 50 r / min. Nitrogen was passed through the ball milling process for protection. After the ball milling was completed, a mixed powder was obtained;

[0068] 2) Heat 10 g of ethanol to 50 ° C using a water bath heating method, add 2 g of stearic acid, and after it dissolves, pour it into the mixed powder obtained in step 1, stir into a paste, and then place it in a vacuum drying oven at 60 ° C and dry it for 2 hours. After it is fully dried, take it out and sieve it using a 30-mesh sieve to obtain a granulated powder. The powder is mechanically formed by molding, weighing 2.5 g of powder each time, and the pressing pressure is 200 MPa to obtain a bone rod-shaped embryo;

[0069] 3) Sintering the embryonic body, placing it in a vacuum sintering furnace and evacuating it, then sintering it at a low temperature of 150° C. for 10 minutes, sintering it at 900° C. for 30 minutes, and finally sintering it at a high temperature of 1150° C. for 2 hours to obtain the high-boron iron-chromium-aluminum alloy porous material.

[0070] The obtained porous material was subjected to metallographic characterization. Figure 2 As shown. Figure 2 It can be seen that distinct island structures have formed on the surface of the porous high-boron iron-chromium-aluminum alloy material of the present invention. These island structures are actually deep protective oxide films remaining after polishing. This indicates that the protective film formed by the present invention is deeper and has a superior protective effect. Similarly, EDS characterization of the surface was performed. The characterization results show that the boron content on the surface of the porous high-boron iron-chromium-aluminum alloy material of the present invention is extremely high, effectively forming a boron-rich layer.

[0071] Example 2

[0072] A high-boron iron-chromium-aluminum alloy porous material, the preparation process of which is as follows Figure 1 As shown,

[0073] The specific process includes:

[0074] 1) 55 g of iron powder, 20 g of chromium powder, 25 g of aluminum powder, and 0.5 g of boron powder were mixed evenly, and ball milling was performed with small balls. The ball-to-material mass ratio was 2:1. The ball milling speed was controlled at 50 r / min. Nitrogen was passed through the ball milling process for protection. After the ball milling was completed, a mixed powder was obtained;

[0075] 2) Heat 10 g of ethanol to 50 ° C using a water bath heating method, add 2 g of stearic acid, and after it dissolves, pour it into the mixed powder obtained in step 1, stir into a paste, and then place it in a vacuum drying oven at 60 ° C and dry it for 2 hours. After it is fully dried, take it out and sieve it using a 30-mesh sieve to obtain a granulated powder. The powder is mechanically formed by molding, weighing 2.5 g of powder each time, and the pressing pressure is 200 MPa to obtain a bone rod-shaped embryo;

[0076] 3) Sintering the embryonic body, placing it in a vacuum sintering furnace and evacuating it, then sintering it at a low temperature of 150° C. for 10 minutes, sintering it at 900° C. for 30 minutes, and finally sintering it at a high temperature of 1150° C. for 2 hours to obtain the high-boron iron-chromium-aluminum alloy porous material.

[0077] Example 3

[0078] A high-boron iron-chromium-aluminum alloy porous material, the preparation process of which is as follows Figure 1 As shown,

[0079] The specific process includes:

[0080] 1) 85 g of iron powder, 10 g of chromium powder, 5 g of aluminum powder, and 0.5 g of boron powder were mixed evenly, and ball milling was performed with small balls. The ball-to-material mass ratio was 2:1. The ball milling speed was controlled at 50 r / min. Nitrogen was passed through the ball milling process for protection. After the ball milling was completed, a mixed powder was obtained;

[0081] 2) Heat 10 g of ethanol to 50 ° C using a water bath heating method, add 2 g of stearic acid, and after it dissolves, pour it into the mixed powder obtained in step 1, stir into a paste, and then place it in a vacuum drying oven at 60 ° C and dry it for 2 hours. After it is fully dried, take it out and sieve it using a 30-mesh sieve to obtain a granulated powder. The powder is mechanically formed by molding, weighing 2.5 g of powder each time, and the pressing pressure is 200 MPa to obtain a bone rod-shaped embryo;

[0082] 3) Sintering the embryonic body, placing it in a vacuum sintering furnace and evacuating it, then sintering it at a low temperature of 150° C. for 10 minutes, sintering it at 900° C. for 30 minutes, and finally sintering it at a high temperature of 1150° C. for 2 hours to obtain the high-boron iron-chromium-aluminum alloy porous material.

[0083] Comparative Example 1

[0084] A porous iron-chromium-aluminum alloy material, the preparation process of which is as follows Figure 1 As shown,

[0085] The specific process includes:

[0086] 1) 71 g of iron powder, 14 g of chromium powder, and 15 g of aluminum powder were mixed uniformly, and ball milling was performed with small balls. The ball-to-material mass ratio was 2:1. The ball milling speed was controlled at 50 r / min. Nitrogen was passed through the ball milling process for protection. After the ball milling was completed, a mixed powder was obtained;

[0087] 2) Heat 10 g of ethanol to 50 ° C using a water bath heating method, add 2 g of stearic acid, and after it dissolves, pour it into the mixed powder obtained in step 1, stir into a paste, and then place it in a vacuum drying oven at 60 ° C and dry it for 2 hours. After it is fully dried, take it out and sieve it using a 30-mesh sieve to obtain a granulated powder. The powder is mechanically formed by molding, weighing 2.5 g of powder each time, and the pressing pressure is 200 MPa to obtain a bone rod-shaped embryo;

[0088] 3) Sintering the embryonic body, placing it in a vacuum sintering furnace and evacuating it, then sintering it at a low temperature of 150° C. for 10 minutes, sintering it at 900° C. for 30 minutes, and finally sintering it at a high temperature of 1150° C. for 2 hours to obtain the iron-chromium-aluminum alloy porous material.

[0089] Test I

[0090] The porous alloy materials of Examples 1 to 3 and Comparative Example 1 were characterized. All characterization results were recorded as average values.

[0091] The specific characterization results include the following aspects.

[0092] 1. Physical properties characterization:

[0093] The characterization results are shown in the following table.

[0094]

[0095]

[0096] From the above results, it can be seen that the addition of boron by the method of the present invention has no significant effect on the open porosity of the material, but has a certain optimization effect on the tensile strength and elongation at break of the material, thereby improving the mechanical properties of the material.

[0097] 2. Characterization of protection time:

[0098] The sample was placed in an air atmosphere for oxidation at 800°C. Samples were taken and weighed every 30 minutes, and the weight gain rate compared to the initial weight was calculated. The characterization results are shown in the following table.

[0099] Sample source 30min 60min 90 minutes 120 minutes 150min 180 minutes Example 1 +1.02％ +1.07％ +1.07％ +1.08％ +1.07％ +1.08％ Example 2 +1.13％ +1.19％ +1.19％ +1.20％ +1.20％ +1.20％ Example 3 +0.96％ +1.01％ +1.02％ +1.02％ +1.02％ +1.02％ Comparative Example 1 +1.36％ +2.32％ +2.56％ +2.63％ +2.66％ +2.67％

[0100] As can be seen from the table above, the porous alloy material prepared by the present invention effectively forms a protective layer within the first 30 minutes. The subsequent weight gain rate during the heating and oxidation process is extremely low, and almost no significant growth occurs after 60 minutes. This shows that the rapidly formed protective layer can provide very effective protection for the porous alloy material. However, the porous alloy material prepared by the experimental group of Comparative Example 1 showed a relatively significant weight gain within 180 minutes, indicating that its oxidation process is continuously ongoing and cannot quickly and effectively achieve oxidation protection. This shows that the porous alloy material prepared by the present invention has very excellent resistance to thermal oxidation aging.

[0101] 3. Characterization of Self-repair Timeliness:

[0102] On the basis of Test 2, Protection Aging Characterization, each group of samples was oxidized to constant weight (about 5h), and then three 1cm long scratches were made on each sample in each group, and then the same characterization test as Test 2, Protection Aging Characterization was carried out.

[0103] The characterization results are shown in the following table.

[0104] Sample source 30min 60min 90 minutes 120 minutes 150min 180 minutes Example 1 +0.11％ +0.11％ +0.11％ +0.11％ +0.11％ +0.12％ Example 2 +0.13％ +0.13％ +0.13％ +0.13％ +0.14％ +0.14％ Example 3 +0.07％ +0.07％ +0.07％ +0.07％ +0.07％ +0.07％ Comparative Example 1 +0.32％ +0.51％ +0.60％ +0.62％ +0.62％ +0.63％

[0105] It can be seen from the above results that the alloy porous material of the present invention has very excellent self-repairing ability, and can show the ability of rapid self-repair and anti-oxidation at 1000°C, and its self-repair timeliness is very significantly improved.

[0106] 4. Characterization of thermal shock resistance:

[0107] The sample was placed in an air atmosphere at 1100°C for oxidation for 27 minutes, and then quickly cooled to below 100°C within 3 minutes. This cycle lasted 30 minutes, and samples were taken and weighed every 30 minutes to calculate the weight gain compared to the initial weight. The characterization results are shown in the following table.

[0108]

[0109]

[0110] As can be seen from the above table, the aging performance of the porous alloy material of the present invention under the working condition of 1100°C is close to that of 800°C, and the growth of the protective layer can be achieved quickly, effectively protecting the porous alloy material. It also has good thermal shock resistance, because the boron self-repairing component can reduce the damage to the porous alloy material during thermal shock. The comparative example 1 test group performed better than the characterization test results under 800°C conditions in the first 30 minutes, but as time went on, it was unable to effectively form a protective layer for antioxidant protection, indicating that, as is well known to the public, its aging performance is improved under high temperature conditions, but its thermal shock resistance is poor.

[0111] Example 4

[0112] A high-boron iron-chromium-aluminum alloy porous material, the preparation process of which is as follows Figure 1 As shown,

[0113] The specific process includes:

[0114] 1) 71 g of iron powder, 14 g of chromium powder, and 15 g of aluminum powder were mixed with 1.5 g of yttrium tetraboride (containing approximately 0.5 g of boron element) powder, and ball milling was performed with a ball-to-material mass ratio of 2:1. The ball milling speed was controlled at 50 r / min. Nitrogen was passed through the ball milling process for protection. After the ball milling was completed, a mixed powder was obtained;

[0115] 2) Heat 10 g of ethanol to 50 ° C using a water bath heating method, add 2 g of stearic acid, and after it dissolves, pour it into the mixed powder obtained in step 1, stir into a paste, and then place it in a vacuum drying oven at 60 ° C and dry it for 2 hours. After it is fully dried, take it out and sieve it using a 30-mesh sieve to obtain a granulated powder. The powder is mechanically formed by molding, weighing 2.5 g of powder each time, and the pressing pressure is 200 MPa to obtain a bone rod-shaped embryo;

[0116] 3) Sintering the embryonic body, placing it in a vacuum sintering furnace and evacuating it, then sintering it at a low temperature of 150° C. for 10 minutes, sintering it at 900° C. for 30 minutes, and finally sintering it at a high temperature of 1150° C. for 2 hours to obtain the iron-chromium-aluminum alloy porous material.

[0117] Comparative Example 2

[0118] A high-boron iron-chromium-aluminum alloy porous material, the preparation process of which is as follows Figure 1 As shown,

[0119] The specific process includes:

[0120] 1) 71 g of iron powder, 14 g of chromium powder, and 15 g of aluminum powder were mixed with 1.55 g of cerium hexaboride (containing approximately 0.5 g of boron element) powder, and ball milling was performed with ball milling balls at a ball-to-material mass ratio of 2:1. The ball milling speed was controlled at 50 r / min, and nitrogen was passed through the ball milling process for protection. After the ball milling was completed, a mixed powder was obtained;

[0121] 2) Heat 10 g of ethanol to 50 ° C using a water bath heating method, add 2 g of stearic acid, and after it dissolves, pour it into the mixed powder obtained in step 1, stir into a paste, and then place it in a vacuum drying oven at 60 ° C and dry it for 2 hours. After it is fully dried, take it out and sieve it using a 30-mesh sieve to obtain a granulated powder. The powder is mechanically formed by molding, weighing 2.5 g of powder each time, and the pressing pressure is 200 MPa to obtain a bone rod-shaped embryo;

[0122] 3) Sintering the embryonic body, placing it in a vacuum sintering furnace and evacuating it, then sintering it at a low temperature of 150° C. for 10 minutes, sintering it at 900° C. for 30 minutes, and finally sintering it at a high temperature of 1150° C. for 2 hours to obtain the iron-chromium-aluminum alloy porous material.

[0123] Comparative Example 3

[0124] A high-boron iron-chromium-aluminum alloy porous material, the preparation process of which is as follows Figure 1 As shown,

[0125] The specific process includes:

[0126] 1) 71 g of iron powder, 14 g of chromium powder, and 15 g of aluminum powder were mixed with 1.54 g of lanthanum hexaboride (containing approximately 0.5 g of boron element) powder, and ball milling was performed with a ball-to-material mass ratio of 2:1. The ball milling speed was controlled at 50 r / min, and nitrogen was passed through the ball milling process for protection. After the ball milling was completed, a mixed powder was obtained;

[0127] 2) Heat 10 g of ethanol to 50 ° C using a water bath heating method, add 2 g of stearic acid, and after it dissolves, pour it into the mixed powder obtained in step 1, stir into a paste, and then place it in a vacuum drying oven at 60 ° C and dry it for 2 hours. After it is fully dried, take it out and sieve it using a 30-mesh sieve to obtain a granulated powder. The powder is mechanically formed by molding, weighing 2.5 g of powder each time, and the pressing pressure is 200 MPa to obtain a bone rod-shaped embryo;

[0128] 3) Sintering the embryonic body, placing it in a vacuum sintering furnace and evacuating it, then sintering it at a low temperature of 150° C. for 10 minutes, sintering it at 900° C. for 30 minutes, and finally sintering it at a high temperature of 1150° C. for 2 hours to obtain the iron-chromium-aluminum alloy porous material.

[0129] Test II

[0130] The porous alloy materials of Example 4 and Comparative Examples 2 to 3 were characterized. All characterization results were recorded as average values.

[0131] The specific characterization results include the following aspects.

[0132] 1. Physical performance characterization:

[0133] The characterization results are shown in the following table.

[0134] Sample source Open porosity (%) Tensile strength (MPa) Elongation at break (%) Example 4 29.27 150.0 3.02 Comparative Example 2 29.21 139.1 3.12 Comparative Example 3 29.32 143.5 3.06

[0135] From the above results, it can be seen that the addition of rare earth elements does not have a significant effect on the open porosity of the material, but can produce a significant strengthening effect for the mechanical properties of the alloy porous material. On the basis of Example 4, the use of yttrium tetraboride alone is replaced by a mixed use of elemental boron and / or yttrium tetraboride and / or yttrium diboride. The boron addition is controlled to be 0.5g, and the addition of yttrium is 0.1~1.5g (gradient is 0.1g) to carry out a single factor orthogonal test, and the sample performance under different yttrium element additions is characterized. The characterization results show that when the addition of yttrium is less than 0.2g, it can not produce a corresponding strengthening effect. And when the yttrium content reaches 1.1g, the sample gradually produces brittleness, and the elongation at break begins to decline. And when the yttrium dosage reaches 1.3g, the elongation at break produces a cliff-like decline. It can be seen that the addition of rare earth elements should also be followed in moderation. After excessive yttrium is added, the structure of the surface boron and the original alloy structure are actually destroyed, resulting in a certain degree of weakening of its mechanical properties. Similarly, on the basis of Example 4, zirconium diboride and elemental boron are mixed and added in a manner such that the boron addition amount is controlled to be 0.5g and the zirconium addition amount is 1.0g, and the same characterization is performed. The characterization results show that the use effects of yttrium and zirconium are basically equivalent.

[0136] 2. Characterization of protection time:

[0137] The sample was placed in an air atmosphere for oxidation at 800°C. Samples were taken and weighed every 30 minutes, and the weight gain rate compared to the initial weight was calculated. The characterization results are shown in the following table.

[0138] Sample source 30min 60min 90 minutes 120 minutes 150min 180 minutes Example 4 +1.06％ +1.09％ +1.10％ +1.10％ +1.10％ +1.10％ Comparative Example 2 +1.22％ +1.97％ +2.23％ +2.51％ +2.55％ +2.56％ Comparative Example 3 +1.19％ +1.99％ +2.52％ +2.81％ +2.95％ +3.02％

[0139] As can be seen from the above table, the alloy porous material obtained after adding yttrium tetraboride of the present invention effectively realizes the formation of a protective layer almost within the first 30 minutes, and the subsequent heating and oxidation process has an extremely low weight gain rate, and almost no significant growth occurs after 90 minutes, indicating that its rapidly formed protective layer can form a very effective protection for the alloy porous material. However, the alloy porous materials obtained by the test groups of Comparative Example 2 and Comparative Example 3 both have a relatively obvious weight gain within 180 minutes, indicating that the oxidation process is constantly ongoing and oxidation protection cannot be achieved quickly and effectively. This shows that the alloy porous material obtained by the present invention has very excellent resistance to thermal oxidation aging. It also shows that the addition of rare earth boride components is not necessarily beneficial compared to the addition of boron, especially after the addition and use of some rare earth components, which leads to a significant weakening of its aging. It can also be clearly seen that for the technical solution of the present invention, the effect of yttrium, a rare earth component, is obviously far superior to other rare earth components.

[0140] 3. Characterization of Self-repair Timeliness:

[0141] On the basis of Test 2, Protection Aging Characterization, each group of samples was oxidized to constant weight (about 5h), and then three 1cm long scratches were made on each sample in each group, and then the same characterization test as Test 2, Protection Aging Characterization was carried out.

[0142] The characterization results are shown in the following table.

[0143] Sample source 30min 60min 90 minutes 120 minutes 150min 180 minutes Example 4 +0.09％ +0.10％ +0.10％ +0.10％ +0.10％ +0.10％ Comparative Example 2 +0.16％ +0.19％ +0.23％ +0.25％ +0.25％ +0.26％ Comparative Example 3 +0.21％ +0.28％ +0.33％ +0.37％ +0.39％ +0.40％

[0144] From the above results, it can be seen that the porous alloy material of the present invention has a very excellent self-repairing ability. It can show the ability of rapid self-repairing and anti-oxidation at 1000°C, and its self-repairing timeliness is significantly improved. It is well known that the addition of rare earth elements can mostly improve the thermal shock resistance of the alloy. However, the self-repairing of Comparative Examples 2 and 3 is still obviously lacking compared with Example 4. It can also be seen from the comparison of Example 1 and Example 4 that the addition of a specific rare earth element (yttrium) also has a certain improvement effect on the self-repairing timeliness.

[0145] Example 5

[0146] A high-boron iron-chromium-aluminum alloy porous material, the preparation process of which is as follows Figure 1 As shown,

[0147] The specific process includes:

[0148] 1) 71 g of iron powder, 14 g of chromium powder, and 15 g of aluminum powder were mixed with 0.5 g of boron powder, and ball milling was performed with a ball-to-material mass ratio of 2:1. The ball milling speed was controlled at 50 r / min. Nitrogen was passed through the ball milling process for protection. After the ball milling was completed, a mixed powder was obtained;

[0149] 2) Heat 10 g of ethanol to 50 ° C using a water bath heating method, add 2 g of stearic acid, and after it dissolves, pour it into the mixed powder obtained in step 1, stir into a paste, and then place it in a vacuum drying oven at 60 ° C and dry it for 2 hours. After it is fully dried, take it out and sieve it using a 30-mesh sieve to obtain a granulated powder. The powder is mechanically formed by molding, weighing 2.5 g of powder each time, and the pressing pressure is 200 MPa to obtain a bone rod-shaped embryo;

[0150] 3) Sintering the embryonic body, placing it in a vacuum sintering furnace and evacuating it, then sintering it at a low temperature of 120° C. for 20 minutes, sintering it at 850° C. for 40 minutes, and finally sintering it at a high temperature of 1100° C. for 2.5 hours to obtain the high-boron iron-chromium-aluminum alloy porous material.

[0151] Example 6

[0152] A high-boron iron-chromium-aluminum alloy porous material, the preparation process of which is as follows Figure 1 As shown,

[0153] The specific process includes:

[0154] 1) 71 g of iron powder, 14 g of chromium powder, and 15 g of aluminum powder were mixed with 0.5 g of boron powder, and ball milling was performed with a ball-to-material mass ratio of 2:1. The ball milling speed was controlled at 50 r / min. Nitrogen was passed through the ball milling process for protection. After the ball milling was completed, a mixed powder was obtained;

[0155] 2) Heat 10 g of ethanol to 50 ° C using a water bath heating method, add 2 g of stearic acid, and after it dissolves, pour it into the mixed powder obtained in step 1, stir into a paste, and then place it in a vacuum drying oven at 60 ° C and dry it for 2 hours. After it is fully dried, take it out and sieve it using a 30-mesh sieve to obtain a granulated powder. The powder is mechanically formed by molding, weighing 2.5 g of powder each time, and the pressing pressure is 200 MPa to obtain a bone rod-shaped embryo;

[0156] 3) Sintering the embryonic body, placing it in a vacuum sintering furnace and evacuating it, then sintering it at a low temperature of 180° C. for 10 minutes, sintering it at 950° C. for 20 minutes, and finally sintering it at a high temperature of 1300° C. for 1.5 hours to obtain the high-boron iron-chromium-aluminum alloy porous material.

[0157] The samples prepared in Examples 5 and 6 were subjected to the same characterization as in Test 1 and compared with those in Example 1. The characterization test results were similar between the groups of samples, with no significant differences. Only the group tested in Example 6 showed slight decreases in thermal shock resistance and mechanical properties.

[0158] Comparative Example 4

[0159] A high-boron iron-chromium-aluminum alloy porous material, the preparation process of which is as follows Figure 1 As shown,

[0160] The specific process includes:

[0161] 1) 71 g of iron powder, 14 g of chromium powder, and 15 g of aluminum powder were mixed with 0.5 g of boron powder, and ball milling was performed with a ball-to-material mass ratio of 2:1. The ball milling speed was controlled at 50 r / min. Nitrogen was passed through the ball milling process for protection. After the ball milling was completed, a mixed powder was obtained;

[0162] 2) Heat 10 g of ethanol to 50 ° C using a water bath heating method, add 2 g of stearic acid, and after it dissolves, pour it into the mixed powder obtained in step 1, stir into a paste, and then place it in a vacuum drying oven at 60 ° C and dry it for 2 hours. After it is fully dried, take it out and sieve it using a 30-mesh sieve to obtain a granulated powder. The powder is mechanically formed by molding, weighing 2.5 g of powder each time, and the pressing pressure is 200 MPa to obtain a bone rod-shaped embryo;

[0163] 3) Sintering the embryonic body, placing it in a vacuum sintering furnace and evacuating the vacuum, sintering it at 900° C. for 40 minutes, and finally sintering it at a high temperature of 1150° C. for 2 hours to obtain the iron-chromium-aluminum alloy porous material.

[0164] Comparative Example 5

[0165] A high-boron iron-chromium-aluminum alloy porous material, the preparation process of which is as follows Figure 1 As shown,

[0166] The specific process includes:

[0167] 1) 71 g of iron powder, 14 g of chromium powder, and 15 g of aluminum powder were mixed with 0.5 g of boron powder, and ball milling was performed with a ball-to-material mass ratio of 2:1. The ball milling speed was controlled at 50 r / min. Nitrogen was passed through the ball milling process for protection. After the ball milling was completed, a mixed powder was obtained;

[0168] 2) Heat 10 g of ethanol to 50 ° C using a water bath heating method, add 2 g of stearic acid, and after it dissolves, pour it into the mixed powder obtained in step 1, stir into a paste, and then place it in a vacuum drying oven at 60 ° C and dry it for 2 hours. After it is fully dried, take it out and sieve it using a 30-mesh sieve to obtain a granulated powder. The powder is mechanically formed by molding, weighing 2.5 g of powder each time, and the pressing pressure is 200 MPa to obtain a bone rod-shaped embryo;

[0169] 3) Sintering the embryonic body, placing it in a vacuum sintering furnace and evacuating the vacuum, sintering it at 150° C. for 40 minutes, and finally sintering it at a high temperature of 1150° C. for 2 hours to obtain the iron-chromium-aluminum alloy porous material.

[0170] Comparative Example 6

[0171] A high-boron iron-chromium-aluminum alloy porous material, the preparation process of which is as follows Figure 1 As shown,

[0172] The specific process includes:

[0173] 1) 71 g of iron powder, 14 g of chromium powder, and 15 g of aluminum powder were mixed with 0.5 g of boron powder, and ball milling was performed with a ball-to-material mass ratio of 2:1. The ball milling speed was controlled at 50 r / min. Nitrogen was passed through the ball milling process for protection. After the ball milling was completed, a mixed powder was obtained;

[0174] 2) Heat 10 g of ethanol to 50 ° C using a water bath heating method, add 2 g of stearic acid, and after it dissolves, pour it into the mixed powder obtained in step 1, stir into a paste, and then place it in a vacuum drying oven at 60 ° C and dry it for 2 hours. After it is fully dried, take it out and sieve it using a 30-mesh sieve to obtain a granulated powder. The powder is mechanically formed by molding, weighing 2.5 g of powder each time, and the pressing pressure is 200 MPa to obtain a bone rod-shaped embryo;

[0175] 3) Sintering the embryonic body, placing it in a vacuum sintering furnace and evacuating the vacuum, and then sintering it at a high temperature of 1150° C. for 2 hours to obtain the iron-chromium-aluminum alloy porous material.

[0176] Test III

[0177] Comparative Examples 4, 5, and 6 were subjected to the same characterization as in Test 1 and compared with the sample of Example 1.

[0178] The comparison results show:

[0179] Compared with Example 1, Comparative Example 4 showed a significant decrease in open porosity, only about 26.13%, and a slight decrease in mechanical properties. In terms of protection timeliness, the samples in the comparative example 4 test group were able to form an effective protective layer after about 90 minutes, which was a certain decrease compared to Example 1. The self-repair timeliness was also worse than that of Example 1. Under thermal shock conditions, the samples in comparative example 4 were able to achieve constant weight after about 120 minutes, indicating a significant decrease in actual thermal shock resistance.

[0180] Compared with Example 1, Comparative Example 5 is relatively close to Example 1 in terms of open porosity and mechanical properties. In terms of protection timeliness, the sample in the test group of Comparative Example 5 can effectively form a protective layer after about 120 minutes, and can achieve preliminary self-repair after about 90 minutes, and can maintain a basically constant weight after 120 minutes, indicating that its surface self-repair ability is weakened. The performance under thermal shock conditions is slightly improved compared with Comparative Example 4, and constant weight can be achieved after about 90 minutes.

[0181] Compared with Example 1, Comparative Example 6 has a significant decrease in protection timeliness, self-repair timeliness and thermal shock resistance, except that the open-pore porosity and mechanical properties are relatively close to Example 1. The formation and self-repair of the protective layer need to be completed in about 150 minutes.

[0182] Based on the above-mentioned characterization test results, further research was conducted. The boron content in the surface layer of the sample (surface layer 500μm thickness) was characterized, and the characterization results showed that the boron content of the surface layer of Examples 1 to 6 was about 6-9wt%, forming a boron-rich layer, which became a "boron trap" for regulating boron distribution and providing a "boron source" required for high-temperature self-repair, while the boron content of the surface layer of Comparative Example 4 was only about 3.7wt%, the boron content of the surface layer of Comparative Example 5 was only about 2.9wt%, and the boron content of the surface layer of Comparative Example 6 was only about 0.7wt%, showing significant differences. This shows that for the technical solution of the present invention, boron cannot be simply added to achieve effective performance improvement, but needs to be combined with a specific heat treatment process to further form a boron-rich layer on the surface of the alloy porous material in order to produce the corresponding effect.

Claims

1. A method for preparing a high-boron iron-chromium-aluminum alloy porous material, characterized in that: The method comprises: 1) Mixing metal powder and / or alloy powder containing iron, chromium and aluminum with boron-containing powder to obtain a mixed powder; 2) Granulate the mixed powder and press it into embryos; 3) sintering the embryo to obtain the high-boron iron-chromium-aluminum alloy porous material; Step 3) sintering: first sinter at 120-180°C for 10-20 minutes, then sinter at 850-950°C for 30-120 minutes, and finally sinter at 1100-1300°C for 1.5-2.5 hours; Step 1) In the metal powder and / or alloy powder: The Cr content is 10-20 wt%, the Al content is 5-25 wt%, and the balance is Fe; Step 1) The boron content in the boron-containing powder is greater than or equal to 0.5 wt% of the mass of the metal powder and / or alloy powder.

2. The method for preparing a high-boron iron-chromium-aluminum alloy porous material according to claim 1, characterized in that: The mesh size of the metal powder and / or alloy powder is 200-500 meshes.

3. The method for preparing a high-boron iron-chromium-aluminum alloy porous material according to claim 1, characterized in that: Step 1) The boron-containing powder is elemental boron and / or ferroboron and / or boron-yttrium composite powder and / or boron-zirconium composite powder.

4. The method for preparing a high-boron iron-chromium-aluminum alloy porous material according to claim 1, 2 or 3, characterized in that: Step 1) The mixing process is as follows: Add ball milling balls for ball milling, with a ball-to-material mass ratio of (2-4):1, and control the ball milling speed at 40-60 r / min; Inert gas is used for protection during the ball milling process.

5. The method for preparing a high-boron iron-chromium-aluminum alloy porous material according to claim 1, characterized in that: Step 2) The granulation process is as follows: The mixed powder and the binder are mixed evenly, stirred until they become a paste, and dried and sieved under protective atmosphere or vacuum conditions.

6. The method for preparing a high-boron iron-chromium-aluminum alloy porous material according to claim 5, characterized in that: The binder is an ethanol solution of stearic acid; The mass ratio of stearic acid to ethanol in the stearic acid ethanol solution is (0.05-0.2):1; The mass ratio of the stearic acid to the mixed powder is (0.01-0.04):

1.

7. The method for preparing a high-boron iron-chromium-aluminum alloy porous material according to claim 1, characterized in that: During step 2), the pressing pressure is 150-400 MPa.

8. The method for preparing a high-boron iron-chromium-aluminum alloy porous material according to claim 1, characterized in that: Step 3) The sintering process is carried out under vacuum conditions.

9. A high-boron iron-chromium-aluminum alloy porous material prepared by the method according to any one of claims 1 to 8.

Images