Preparation method of corrosion-resistant high-strength iron-based alloy composite metal cabinet

Abstract

The present invention relates to the field of metal powder metallurgy, and in particular to a method for preparing a corrosion-resistant, high-strength iron-based alloy composite metal cabinet. The method comprises the following steps: (a) preparing iron-based alloy powder; (b) pressing the iron-based alloy powder under a first pressure to form a first green compact; (c) applying a corrosion-resistant reinforcing slurry to the surface of the first green compact, followed by a second pressing under a second pressure to obtain a second green compact; and (d) sintering the second green compact to obtain cabinet panels, which are then assembled to form a corrosion-resistant, high-strength iron-based alloy composite metal cabinet. This method achieves high strength and corrosion resistance for the cabinet by optimizing the iron-based alloy composition and process design.

Description

Technical Field

[0001] The present invention relates to the field of metal powder metallurgy, and in particular to a method for preparing a corrosion-resistant high-strength iron-based alloy composite metal cabinet. Background Art

[0002] Metal cabinets (such as electrical control cabinets and chemical storage cabinets) are widely used in the industrial field, and their performance directly affects the reliability and service life of the equipment. Current commercial metal cabinets mainly use stainless steel or carbon steel coated structures, but these materials and preparation processes have significant defects: although stainless steel has excellent corrosion resistance, it has high density and high cost, making it difficult to meet the needs of lightweight and economical design; carbon steel cabinets rely on organic coatings for corrosion protection, which have problems such as weak bonding and easy peeling, especially in the welding area, which is prone to localized corrosion failure, resulting in a decrease in overall protective performance. In addition, existing powder metallurgy iron-based alloy cabinets attempt to improve corrosion resistance by adding high chromium, but the high chromium content significantly increases the difficulty of sintering and causes the material's ductility to deteriorate, limiting its practical application. Traditional surface plating or coating technologies have difficulty achieving uniform protection on complex cabinet structures, especially in corrosion protection of weld areas, where there is a clear technical gap, further exacerbating the lack of corrosion resistance of the entire cabinet structure. Patent Publication No. CN112251105B proposes a composite material consisting of a metal substrate, a functional coating, and a metal coating, using a nickel-based alloy as a transition layer to enhance interfacial bonding. While this solution demonstrates excellent corrosion resistance, high-temperature resistance, and mechanical strength, the bonding between the functional coating and the metal substrate is limited by the interface treatment process, and there is a risk of delamination during long-term use. Furthermore, the introduction of a nickel-based alloy transition layer not only increases material cost and manufacturing complexity, but also presents technical challenges in achieving uniform coating across large, complex cabinet structures, making it difficult to meet the industrial demand for high-performance cabinets. Another patent, Publication No. CN108465789B, achieves the integrated formation of bimetallic composite sheets through a continuous casting process, addressing the shortcomings of traditional composite materials in interfacial bonding and uniformity. However, this solution primarily addresses the preparation of bimetallic sheets and does not address the molding process for complex cabinet structures, particularly optimizing corrosion resistance in weld zones and edge regions. Furthermore, the continuous casting process requires high equipment requirements, and production costs and technical barriers limit its widespread application in the manufacturing of small and medium-sized cabinets.

[0003] Integrated molding of large industrial metal cabinets is difficult to achieve. Existing large industrial metal cabinets are mostly assembled, and their strength and corrosion resistance are still significantly insufficient. Therefore, there is an urgent need to develop an iron-based alloy material that is lightweight, high-strength, tough, and corrosion-resistant, suitable for cabinet manufacturing, to address these technical challenges and meet the industrial demand for high-performance metal cabinets. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a method for preparing a corrosion-resistant and high-strength iron-based alloy composite metal cabinet, aiming to achieve high strength and corrosion resistance of the cabinet by optimizing the iron-based alloy composition and process design.

[0005] The technical solution adopted by the present invention to solve the technical problem is: to provide a method for preparing a corrosion-resistant high-strength iron-based alloy composite metal cabinet, comprising the following steps:

[0006] A method for preparing a corrosion-resistant high-strength iron-based alloy composite metal cabinet comprises the following steps:

[0007] Step (a) prepares iron-based alloy powder, which comprises, by mass percentage:

[0008] C:0.01-0.05%,

[0009] Cr:1.2-2.5%,

[0010] Mo: 0.3-0.8%,

[0011] V:0.1-0.3%,

[0012] Balance Fe and unavoidable impurities;

[0013] Step (b), pressing the iron-based alloy powder under a first pressure to form a first green compact;

[0014] Step (c), applying the corrosion-resistant reinforcing slurry to the surface of the first green body, drying until the residual solvent content is ≤0.2 wt %, and performing a secondary pressing under a second pressure to obtain a second green body; the coating may be performed by dipping, spraying, or brushing;

[0015] The composition of the corrosion-resistant reinforcement slurry is as follows by mass percentage:

[0016] Nano Cr powder: 10-20wt%,

[0017] Nano Ni powder: 5-10wt%,

[0018] Nano magnesium carbonate: 3-5wt%,

[0019] Iron-based alloy powder: 25-35 wt %. The iron-based alloy powder has the same chemical composition as the iron-based alloy powder prepared in step (a). Its main function is to form a continuous metal skeleton in the slurry that is well compatible with the green body matrix material, i.e., a homogeneous skeleton structure;

[0020] Binder: 1-2wt%,

[0021] Dispersant: 0.1-0.3wt%,

[0022] Solvent: balance;

[0023] Step (d): the second green body is sintered to obtain cabinet panels, which are assembled and formed to obtain a corrosion-resistant, high-strength iron-based alloy composite metal cabinet.

[0024] This preparation method utilizes homogeneous matrix powder as the main component of the corrosion-resistant slurry, which can construct a continuous metal skeleton network, so that nano-chromium powder, nickel powder and magnesium carbonate particles are evenly dispersed in the alloy matrix; in the subsequent secondary pressing process, the homogeneous matrix powder and the green matrix produce plastic cooperative deformation, eliminating the pressing stress concentration caused by composition differences; during sintering, the homogeneous skeleton guides the chromium and nickel elements to diffuse directionally along the iron lattice, forming a corrosion-resistant layer with a composition gradient transition, and at the same time, its thermal expansion coefficient is completely matched with the matrix, suppressing the risk of interface delamination; magnesium carbonate is thermally decomposed under the wrapping of the iron-based powder, and the generated microporous channels are confined within the skeleton network, realizing the dual regulation of stress release and diffusion enhancement, and finally obtaining a composite plate with metallurgical bonding of matrix and corrosion-resistant layer. Through the first pressing of iron-based alloy powder with specific composition (containing chromium, vanadium and molybdenum microalloying elements) under the first pressure, a green body matrix with a gradient pore structure is formed; the corrosion-resistant reinforcing slurry (containing high-concentration nano-chromium powder, nickel powder and nano-magnesium carbonate) is selectively enriched in the surface pores of the green body by utilizing the capillary penetration effect, and the component distribution is solidified by gradient drying; a second pressing under the second pressure is performed to produce a mechanically interlocked prefabricated composite interface between the corrosion-resistant particles and the matrix; during the sintering process, magnesium carbonate is thermally decomposed to produce micropores, which simultaneously realizes the release of shrinkage stress and the optimization of chromium and nickel diffusion paths, and finally forms a continuous chromium-rich solid solution corrosion-resistant layer on the surface; after the obtained functional gradient plate is assembled, the intrinsic strength provided by the microalloying of the matrix and the surface corrosion-resistant layer work synergistically to achieve the comprehensive performance improvement of the metal cabinet.

[0025] Among them, chromium can form a passivation film precursor in iron, molybdenum can inhibit the expansion of pitting corrosion, and vanadium can pin the grain boundaries through carbonitrides. The three synergistically improve the intrinsic corrosion resistance and strength of the matrix; medium and low pressure pressing forms an open pore network, providing a directional channel for slurry infiltration, ensuring that the corrosion-resistant components are enriched in high concentration on the surface; the decomposition of nano-magnesium carbonate can produce submicron channels, release sintering shrinkage stress, inhibit interface cracking, and at the same time increase the diffusion specific surface area, promoting the deep migration of chromium ions into the matrix; high-pressure pressing embeds nano-corrosion-resistant particles into the matrix skeleton, avoiding component segregation caused by density difference during sintering; in a reducing atmosphere, the chromium-rich layer forms a continuous solid solution through solid-phase diffusion, and the decomposition channels of magnesium carbonate guide the chromium ions to diffuse rapidly along the grain boundaries, realizing metallurgical bonding between the corrosion-resistant layer and the matrix.

[0026] Preferably, the iron-based alloy powder in step (a) has a particle size of less than 80 μm, and a main particle size distribution of:

[0027] 45-75μm particles account for 30±5wt%,

[0028] 10-25μm particles account for 50±5wt%.

[0029] It is inevitable that there is a portion of ultrafine powder.

[0030] Preferably, the binder is polyvinyl butyral, the solvent is anhydrous ethanol, and the dispersant is ammonium polyacrylate.

[0031] Preferably, the first pressure is 80-120 MPa.

[0032] Preferably, the amount of the corrosion-resistant enhancement slurry applied in step (c) is 0.5-0.8 g per square centimeter.

[0033] Preferably, after the corrosion-resistant reinforcing slurry is applied in step (c), it is allowed to stand for 1-2 minutes under a pressure of 0.08-0.09 MPa, and then dried at 40-60° C. under an inert atmosphere.

[0034] Preferably, the second pressure is 400-500 MPa.

[0035] Preferably, in step (d), the sintering process is:

[0036] The first stage: heat up to 300-400℃ at 1-3℃ / min and keep warm for 20-40min.

[0037] The second stage: heat up to 1150-1200℃ at 4-6℃ / min and keep warm for 60-120min.

[0038] The third stage: forced cooling to below 600°C, followed by air cooling to room temperature.

[0039] Preferably, the forced cooling process of the third stage is: argon gas jet cooling, with a cooling rate ≥50°C / min.

[0040] Preferably, the assembly forming method is welding, riveting or hinging, and the surface is coated with an anti-rust layer after assembly is completed.

[0041] The beneficial effects of the present invention are:

[0042] 1. From the perspective of composition: The slurry is mainly composed of homogeneous iron-based alloy powder, whose chemical composition is completely consistent with that of the green body matrix. During the infiltration process, a continuous metal skeleton is formed, so that the nano-chromium powder, nickel powder and magnesium carbonate are evenly wrapped in the homogeneous matrix network. On the one hand, this eliminates thermal expansion mismatch and avoids interfacial stress concentration during drying and sintering. On the other hand, the homogeneous skeleton guides the directional coupling of the nanoparticles and the matrix lattice, forming a chromium-rich solid solution layer with a gradient transition in composition during sintering. At the same time, it constrains the micropores generated by the decomposition of magnesium carbonate within the skeleton gaps, forming a closed-pore structure to block the invasion path of corrosive media.

[0043] 2. From the process perspective: step-by-step pressing and homogeneous infiltration are synergistically optimized. The gradient pore structure constructed by the first low-pressure pressing provides a directional channel for the capillary penetration of the homogeneous matrix powder in the slurry; the secondary high-pressure pressing utilizes the plastic coordination ability of the homogeneous powder to produce a mechanical-metallurgical double interlocking of the nano-corrosion-resistant components and the green matrix, and relies on the lattice continuity of the homogeneous metal skeleton during sintering to eliminate stress cracking introduced by different thermal expansion, thereby ensuring high-strength performance. DETAILED DESCRIPTION

[0044] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] Example 1

[0046] A method for preparing a corrosion-resistant high-strength iron-based alloy composite metal cabinet comprises the following steps:

[0047] Step (a): prepare an iron-based alloy powder with a particle size of less than 80 μm and a main particle size distribution of:

[0048] 45-75μm particles account for 35wt%,

[0049] 10-25 μm particles account for 52 wt%;

[0050] The components by mass percentage include:

[0051] C:0.03%,

[0052] Cr:1.8%,

[0053] Mo: 0.5%,

[0054] V:0.2%,

[0055] Balance Fe and unavoidable impurities;

[0056] Step (b), pressing the iron-based alloy powder at 100 MPa to form a first green compact;

[0057] Step (c), applying the corrosion-resistant reinforcing slurry to the surface of the first green body, standing it at 0.09 MPa for 1 minute, then drying it at 50° C. under a nitrogen atmosphere until the residual solvent content is 0.1 wt %, and pressing it a second time at 500 MPa to obtain a second green body; the coating amount is 0.7 g per square centimeter;

[0058] The composition of the corrosion-resistant reinforcement slurry is as follows by mass percentage:

[0059] Nano Cr powder: 15wt%,

[0060] Nano Ni powder: 8wt%,

[0061] Nano magnesium carbonate: 4wt%,

[0062] Iron-based alloy powder: 30wt%,

[0063] Polyvinyl butyral: 1.5wt%,

[0064] Ammonium polyacrylate: 0.2wt%,

[0065] Anhydrous ethanol: balance;

[0066] Step (d), the second green body is sintered to obtain the cabinet plate, which is then welded and assembled into a shape, and an anti-rust layer is coated on the surface to obtain a corrosion-resistant high-strength iron-based alloy composite metal cabinet; the sintering process is as follows:

[0067] The first stage: heating at 2℃ / min to 350℃ and keeping it for 30min.

[0068] The second stage: heating at 4℃ / min to 1180℃ and keeping it for 90min.

[0069] The third stage: argon jet cooling is used at a cooling rate of 55°C / min, forced cooling to below 600°C, and then air cooling to room temperature.

[0070] Example 2

[0071] A method for preparing a corrosion-resistant high-strength iron-based alloy composite metal cabinet comprises the following steps:

[0072] Step (a): prepare an iron-based alloy powder with a particle size of less than 80 μm and a main particle size distribution of:

[0073] 45-75μm particles account for 33wt%,

[0074] 10-25 μm particles account for 48 wt%;

[0075] The components by mass percentage include:

[0076] C:0.03%,

[0077] Cr:1.8%,

[0078] Mo: 0.5%,

[0079] V:0.2%,

[0080] Balance Fe and unavoidable impurities;

[0081] Step (b), pressing the iron-based alloy powder at 120 MPa to form a first green compact;

[0082] Step (c), applying the corrosion-resistant reinforcing slurry to the surface of the first green body, standing it for 2 minutes under a 0.08 MPa environment, then drying it at 50° C. under a nitrogen atmosphere until the residual solvent content is 0.12 wt %, and pressing it a second time at 500 MPa to obtain a second green body; the coating amount is 0.8 g per square centimeter;

[0083] The composition of the corrosion-resistant reinforcement slurry is as follows by mass percentage:

[0084] Nano Cr powder: 20wt%,

[0085] Nano Ni powder: 10wt%,

[0086] Nano magnesium carbonate: 5wt%,

[0087] Iron-based alloy powder: 35wt%,

[0088] Polyvinyl butyral: 2wt%,

[0089] Ammonium polyacrylate: 0.3wt%,

[0090] Anhydrous ethanol: balance;

[0091] Step (d), the second green body is sintered to obtain the cabinet plate, which is then welded and assembled into a shape, and an anti-rust layer is coated on the surface to obtain a corrosion-resistant high-strength iron-based alloy composite metal cabinet; the sintering process is as follows:

[0092] The first stage: heating at 3℃ / min to 400℃ and keeping it for 20min.

[0093] The second stage: heating at 6℃ / min to 1200℃ and keeping it for 60min.

[0094] The third stage: argon jet cooling is used at a cooling rate of 60°C / min, forced cooling to below 600°C, and then air cooling to room temperature.

[0095] Example 3

[0096] A method for preparing a corrosion-resistant high-strength iron-based alloy composite metal cabinet comprises the following steps:

[0097] Step (a): prepare an iron-based alloy powder with a particle size of less than 80 μm and a main particle size distribution of:

[0098] 45-75μm particles account for 31wt%,

[0099] 10-25 μm particles account for 54 wt%;

[0100] The components by mass percentage include:

[0101] C:0.03%,

[0102] Cr:1.8%,

[0103] Mo: 0.5%,

[0104] V:0.2%,

[0105] Balance Fe and unavoidable impurities;

[0106] Step (b), pressing the iron-based alloy powder at 80 MPa to form a first green compact;

[0107] Step (c), applying the corrosion-resistant reinforcing slurry to the surface of the first green body, standing it at 0.09 MPa for 1 minute, then drying it at 50° C. under a nitrogen atmosphere until the residual solvent content is 0.11 wt%, and pressing it a second time at 400 MPa to obtain a second green body; the coating amount is 0.6 g per square centimeter;

[0108] The composition of the corrosion-resistant reinforcement slurry is as follows by mass percentage:

[0109] Nano Cr powder: 10wt%,

[0110] Nano Ni powder: 5wt%,

[0111] Nano magnesium carbonate: 3wt%,

[0112] Iron-based alloy powder: 25wt%,

[0113] Polyvinyl butyral: 1wt%,

[0114] Ammonium polyacrylate: 0.1wt%,

[0115] Anhydrous ethanol: balance;

[0116] Step (d), the second green body is sintered to obtain the cabinet plate, which is then welded and assembled into a shape, and an anti-rust layer is coated on the surface to obtain a corrosion-resistant high-strength iron-based alloy composite metal cabinet; the sintering process is as follows:

[0117] The first stage: heating at 1℃ / min to 300℃ and keeping it for 40min.

[0118] The second stage: heating at 4℃ / min to 1150℃ and keeping it for 120min.

[0119] The third stage: argon jet cooling is used at a cooling rate of 50°C / min, forced cooling to below 600°C, and then air cooling to room temperature.

[0120] Comparative Example 1

[0121] The difference from Example 1 is that the corrosion-resistant reinforcement slurry is not applied:

[0122] A method for preparing a corrosion-resistant high-strength iron-based alloy composite metal cabinet comprises the following steps:

[0123] Step (a): prepare an iron-based alloy powder with a particle size of less than 80 μm and a main particle size distribution of:

[0124] 45-75μm particles account for 35wt%,

[0125] 10-25 μm particles account for 52 wt%;

[0126] The components by mass percentage include:

[0127] C:0.03%,

[0128] Cr:1.8%,

[0129] Mo: 0.5%,

[0130] V:0.2%,

[0131] Balance Fe and unavoidable impurities;

[0132] Step (b), pressing the iron-based alloy powder at 100 MPa to form a first green compact;

[0133] Step (c) standing for 1 minute under a pressure of 0.09 MPa, and performing a secondary pressing under a pressure of 500 MPa to obtain a second green body;

[0134] Step (d), the second green body is sintered to obtain the cabinet plate, which is then welded and assembled into a shape, and an anti-rust layer is coated on the surface to obtain a corrosion-resistant high-strength iron-based alloy composite metal cabinet; the sintering process is as follows:

[0135] The first stage: heating at 2℃ / min to 350℃ and keeping it for 30min.

[0136] The second stage: heating at 4℃ / min to 1180℃ and keeping it for 90min.

[0137] The third stage: argon jet cooling is used at a cooling rate of 55°C / min, forced cooling to below 600°C, and then air cooling to room temperature.

[0138] Comparative Example 2

[0139] The difference from Example 1 is that the two-step pressing is not performed:

[0140] A method for preparing a corrosion-resistant high-strength iron-based alloy composite metal cabinet comprises the following steps:

[0141] Step (a): prepare an iron-based alloy powder with a particle size of less than 80 μm and a main particle size distribution of:

[0142] 45-75μm particles account for 35wt%,

[0143] 10-25 μm particles account for 52 wt%;

[0144] The components by mass percentage include:

[0145] C:0.03%,

[0146] Cr:1.8%,

[0147] Mo: 0.5%,

[0148] V:0.2%,

[0149] Balance Fe and unavoidable impurities;

[0150] Step (b), pressing the iron-based alloy powder at 500 MPa to form a first green compact;

[0151] Step (c), applying the corrosion-resistant reinforcing slurry to the surface of the first green body, standing it for 1 minute under a 0.09 MPa environment, and then drying it at 50° C. under a nitrogen atmosphere until the residual solvent content is 0.1 wt %, to obtain a second green body; the coating amount is 0.7 g per square centimeter;

[0152] The composition of the corrosion-resistant reinforcement slurry is as follows by mass percentage:

[0153] Nano Cr powder: 15wt%,

[0154] Nano Ni powder: 8wt%,

[0155] Nano magnesium carbonate: 4wt%,

[0156] Iron-based alloy powder: 30wt%,

[0157] Polyvinyl butyral: 1.5wt%,

[0158] Ammonium polyacrylate: 0.2wt%,

[0159] Anhydrous ethanol: balance;

[0160] Step (d), the second green body is sintered to obtain the cabinet plate, which is then welded and assembled into a shape, and an anti-rust layer is coated on the surface to obtain a corrosion-resistant high-strength iron-based alloy composite metal cabinet; the sintering process is as follows:

[0161] The first stage: heating at 2℃ / min to 350℃ and keeping it for 30min.

[0162] The second stage: heating at 4℃ / min to 1180℃ and keeping it for 90min.

[0163] The third stage: argon jet cooling is used at a cooling rate of 55°C / min, forced cooling to below 600°C, and then air cooling to room temperature.

[0164] Comparative Example 3

[0165] The difference from Example 1 is that the corrosion-resistant reinforcement slurry does not contain iron-based alloy powder:

[0166] A method for preparing a corrosion-resistant high-strength iron-based alloy composite metal cabinet comprises the following steps:

[0167] Step (a): prepare an iron-based alloy powder with a particle size of less than 80 μm and a main particle size distribution of:

[0168] 45-75μm particles account for 35wt%,

[0169] 10-25 μm particles account for 52 wt%;

[0170] The components by mass percentage include:

[0171] C:0.03%,

[0172] Cr:1.8%,

[0173] Mo: 0.5%,

[0174] V:0.2%,

[0175] Balance Fe and unavoidable impurities;

[0176] Step (b), pressing the iron-based alloy powder at 100 MPa to form a first green compact;

[0177] Step (c), applying the corrosion-resistant reinforcing slurry to the surface of the first green body, standing it at 0.09 MPa for 1 minute, then drying it at 50° C. under a nitrogen atmosphere until the residual solvent content is 0.1 wt %, and pressing it a second time at 500 MPa to obtain a second green body; the coating amount is 0.7 g per square centimeter;

[0178] The composition of the corrosion-resistant reinforcement slurry is as follows by mass percentage:

[0179] Nano Cr powder: 15wt%,

[0180] Nano Ni powder: 8wt%,

[0181] Nano magnesium carbonate: 4wt%,

[0182] Polyvinyl butyral: 1.5wt%,

[0183] Ammonium polyacrylate: 0.2wt%,

[0184] Anhydrous ethanol: balance;

[0185] Step (d), the second green body is sintered to obtain the cabinet plate, which is then welded and assembled into a shape, and an anti-rust layer is coated on the surface to obtain a corrosion-resistant high-strength iron-based alloy composite metal cabinet; the sintering process is as follows:

[0186] The first stage: heating at 2℃ / min to 350℃ and keeping it for 30min.

[0187] The second stage: heating at 4℃ / min to 1180℃ and keeping it for 90min.

[0188] The third stage: argon jet cooling is used at a cooling rate of 55°C / min, forced cooling to below 600°C, and then air cooling to room temperature.

[0189] Comparative Example 4

[0190] The difference from Example 1 is that the iron-based alloy powder is excessive in the corrosion-resistant reinforcement slurry:

[0191] A method for preparing a corrosion-resistant high-strength iron-based alloy composite metal cabinet comprises the following steps:

[0192] Step (a): prepare an iron-based alloy powder with a particle size of less than 80 μm and a main particle size distribution of:

[0193] 45-75μm particles account for 35wt%,

[0194] 10-25 μm particles account for 52 wt%;

[0195] The components by mass percentage include:

[0196] C:0.03%,

[0197] Cr:1.8%,

[0198] Mo: 0.5%,

[0199] V:0.2%,

[0200] Balance Fe and unavoidable impurities;

[0201] Step (b), pressing the iron-based alloy powder at 100 MPa to form a first green compact;

[0202] Step (c), applying the corrosion-resistant reinforcing slurry to the surface of the first green body, standing it at 0.09 MPa for 1 minute, then drying it at 50° C. under a nitrogen atmosphere until the residual solvent content is 0.1 wt %, and pressing it a second time at 500 MPa to obtain a second green body; the coating amount is 0.7 g per square centimeter;

[0203] The composition of the corrosion-resistant reinforcement slurry is as follows by mass percentage:

[0204] Nano Cr powder: 15wt%,

[0205] Nano Ni powder: 8wt%,

[0206] Nano magnesium carbonate: 4wt%,

[0207] Iron-based alloy powder: 40wt%,

[0208] Polyvinyl butyral: 1.5wt%,

[0209] Ammonium polyacrylate: 0.2wt%,

[0210] Anhydrous ethanol: balance;

[0211] Step (d), the second green body is sintered to obtain the cabinet plate, which is then welded and assembled into a shape, and an anti-rust layer is coated on the surface to obtain a corrosion-resistant high-strength iron-based alloy composite metal cabinet; the sintering process is as follows:

[0212] The first stage: heating at 2℃ / min to 350℃ and keeping it for 30min.

[0213] The second stage: heating at 4℃ / min to 1180℃ and keeping it for 90min.

[0214] The third stage: argon jet cooling is used at a cooling rate of 55°C / min, forced cooling to below 600°C, and then air cooling to room temperature.

[0215] Comparative Example 5

[0216] The difference from Example 1 is that the corrosion-resistant enhancement slurry does not contain nano-magnesium carbonate:

[0217] A method for preparing a corrosion-resistant high-strength iron-based alloy composite metal cabinet comprises the following steps:

[0218] Step (a): prepare an iron-based alloy powder with a particle size of less than 80 μm and a main particle size distribution of:

[0219] 45-75μm particles account for 35wt%,

[0220] 10-25 μm particles account for 52 wt%;

[0221] The components by mass percentage include:

[0222] C:0.03%,

[0223] Cr:1.8%,

[0224] Mo: 0.5%,

[0225] V:0.2%,

[0226] Balance Fe and unavoidable impurities;

[0227] Step (b), pressing the iron-based alloy powder at 100 MPa to form a first green compact;

[0228] Step (c), applying the corrosion-resistant reinforcing slurry to the surface of the first green body, standing it at 0.09 MPa for 1 minute, then drying it at 50° C. under a nitrogen atmosphere until the residual solvent content is 0.1 wt %, and pressing it a second time at 500 MPa to obtain a second green body; the coating amount is 0.7 g per square centimeter;

[0229] The composition of the corrosion-resistant reinforcement slurry is as follows by mass percentage:

[0230] Nano Cr powder: 15wt%,

[0231] Nano Ni powder: 8wt%,

[0232] Iron-based alloy powder: 30wt%,

[0233] Polyvinyl butyral: 1.5wt%,

[0234] Ammonium polyacrylate: 0.2wt%,

[0235] Anhydrous ethanol: balance;

[0236] Step (d), the second green body is sintered to obtain the cabinet plate, which is then welded and assembled into a shape, and an anti-rust layer is coated on the surface to obtain a corrosion-resistant high-strength iron-based alloy composite metal cabinet; the sintering process is as follows:

[0237] The first stage: heating at 2℃ / min to 350℃ and keeping it for 30min.

[0238] The second stage: heating at 4℃ / min to 1180℃ and keeping it for 90min.

[0239] The third stage: argon jet cooling is used at a cooling rate of 55°C / min, forced cooling to below 600°C, and then air cooling to room temperature.

[0240] Comparative Example 6

[0241] The difference from Example 1 is that the residual solvent is too high:

[0242] A method for preparing a corrosion-resistant high-strength iron-based alloy composite metal cabinet comprises the following steps:

[0243] Step (a): prepare an iron-based alloy powder with a particle size of less than 80 μm and a main particle size distribution of:

[0244] 45-75μm particles account for 35wt%,

[0245] 10-25 μm particles account for 52 wt%;

[0246] The components by mass percentage include:

[0247] C:0.03%,

[0248] Cr:1.8%,

[0249] Mo: 0.5%,

[0250] V:0.2%,

[0251] Balance Fe and unavoidable impurities;

[0252] Step (b), pressing the iron-based alloy powder at 100 MPa to form a first green compact;

[0253] Step (c), applying the corrosion-resistant reinforcing slurry to the surface of the first green body, standing it at 0.09 MPa for 1 minute, then drying it at 50° C. under a nitrogen atmosphere until the residual solvent content is 0.35 wt%, and pressing it a second time at 500 MPa to obtain a second green body; the coating amount is 0.7 g per square centimeter;

[0254] The composition of the corrosion-resistant reinforcement slurry is as follows by mass percentage:

[0255] Nano Cr powder: 15wt%,

[0256] Nano Ni powder: 8wt%,

[0257] Nano magnesium carbonate: 4wt%,

[0258] Iron-based alloy powder: 30wt%,

[0259] Polyvinyl butyral: 1.5wt%,

[0260] Ammonium polyacrylate: 0.2wt%,

[0261] Anhydrous ethanol: balance;

[0262] Step (d), the second green body is sintered to obtain the cabinet plate, which is then welded and assembled into a shape, and an anti-rust layer is coated on the surface to obtain a corrosion-resistant high-strength iron-based alloy composite metal cabinet; the sintering process is as follows:

[0263] The first stage: heating at 2℃ / min to 350℃ and keeping it for 30min.

[0264] The second stage: heating at 4℃ / min to 1180℃ and keeping it for 90min.

[0265] The third stage: argon jet cooling is used at a cooling rate of 55°C / min, forced cooling to below 600°C, and then air cooling to room temperature.

[0266] Comparative Example 7

[0267] The difference from Example 1 is that the iron-based alloy powder has too fine a particle size:

[0268] A method for preparing a corrosion-resistant high-strength iron-based alloy composite metal cabinet comprises the following steps:

[0269] Step (a): prepare an iron-based alloy powder with a particle size of less than 80 μm and a main particle size distribution of:

[0270] 45-75μm particles account for 15wt%,

[0271] 10-25μm particles account for 70wt%;

[0272] The components by mass percentage include:

[0273] C:0.03%,

[0274] Cr:1.8%,

[0275] Mo: 0.5%,

[0276] V:0.2%,

[0277] Balance Fe and unavoidable impurities;

[0278] Step (b), pressing the iron-based alloy powder at 100 MPa to form a first green compact;

[0279] Step (c), applying the corrosion-resistant reinforcing slurry to the surface of the first green body, standing it at 0.09 MPa for 1 minute, then drying it at 50° C. under a nitrogen atmosphere until the residual solvent content is 0.1 wt %, and pressing it a second time at 500 MPa to obtain a second green body; the coating amount is 0.7 g per square centimeter;

[0280] The composition of the corrosion-resistant reinforcement slurry is as follows by mass percentage:

[0281] Nano Cr powder: 15wt%,

[0282] Nano Ni powder: 8wt%,

[0283] Nano magnesium carbonate: 4wt%,

[0284] Iron-based alloy powder: 30wt%,

[0285] Polyvinyl butyral: 1.5wt%,

[0286] Ammonium polyacrylate: 0.2wt%,

[0287] Anhydrous ethanol: balance;

[0288] Step (d), the second green body is sintered to obtain the cabinet plate, which is then welded and assembled into a shape, and an anti-rust layer is coated on the surface to obtain a corrosion-resistant high-strength iron-based alloy composite metal cabinet; the sintering process is as follows:

[0289] The first stage: heating at 2℃ / min to 350℃ and keeping it for 30min.

[0290] The second stage: heating at 4℃ / min to 1180℃ and keeping it for 90min.

[0291] The third stage: argon jet cooling is used at a cooling rate of 55°C / min, forced cooling to below 600°C, and then air cooling to room temperature.

[0292] Comparative Example 8

[0293] The difference from Example 1 is that, in step (c), after the corrosion-resistant reinforcement slurry is applied to the surface of the first green body, low-pressure treatment is not performed:

[0294] A method for preparing a corrosion-resistant high-strength iron-based alloy composite metal cabinet comprises the following steps:

[0295] Step (a): prepare an iron-based alloy powder with a particle size of less than 80 μm and a main particle size distribution of:

[0296] 45-75μm particles account for 35wt%,

[0297] 10-25 μm particles account for 52 wt%;

[0298] The components by mass percentage include:

[0299] C:0.03%,

[0300] Cr:1.8%,

[0301] Mo: 0.5%,

[0302] V:0.2%,

[0303] Balance Fe and unavoidable impurities;

[0304] Step (b), pressing the iron-based alloy powder at 100 MPa to form a first green compact;

[0305] Step (c), applying the corrosion-resistant reinforcing slurry to the surface of the first green body, then drying at 50° C. under a nitrogen atmosphere until the residual solvent content is 0.1 wt %, and performing a secondary pressing at 500 MPa to obtain a second green body; the coating amount is 0.7 g per square centimeter;

[0306] The composition of the corrosion-resistant reinforcement slurry is as follows by mass percentage:

[0307] Nano Cr powder: 15wt%,

[0308] Nano Ni powder: 8wt%,

[0309] Nano magnesium carbonate: 4wt%,

[0310] Iron-based alloy powder: 30wt%,

[0311] Polyvinyl butyral: 1.5wt%,

[0312] Ammonium polyacrylate: 0.2wt%,

[0313] Anhydrous ethanol: balance;

[0314] Step (d), the second green body is sintered to obtain the cabinet plate, which is then welded and assembled into a shape, and an anti-rust layer is coated on the surface to obtain a corrosion-resistant high-strength iron-based alloy composite metal cabinet; the sintering process is as follows:

[0315] The first stage: heating at 2℃ / min to 350℃ and keeping it for 30min.

[0316] The second stage: heating at 4℃ / min to 1180℃ and keeping it for 90min.

[0317] The third stage: argon jet cooling is used at a cooling rate of 55°C / min, forced cooling to below 600°C, and then air cooling to room temperature.

[0318] The performance test is a sampling test of corrosion-resistant high-strength iron-based alloy composite metal cabinet body panels, with reference to the following standards:

[0319] Mechanical properties: ASTM E8 / E8M (tensile), ASTM E384 (hardness);

[0320] Corrosion resistance: ASTM B117 (salt spray), ASTM G59 (electrochemical polarization);

[0321] Lightweight index: density (ISO3369).

[0322] The test results are shown in Table 1.

[0323] Table 1 Performance test of examples and comparative examples

[0324]

[0325] Examples 1-3 have significant performance improvements compared to Comparative Examples 1-8 and 304 stainless steel. Different from the homogeneous alloying path of 304 stainless steel, this solution relies on the powder metallurgy step-by-step pressing process. The matrix is ​​micro-alloyed to achieve fine grain strengthening to ensure overall strength, while the surface layer uses a gradient pore network to directionally enrich high-concentration corrosion-resistant components. In terms of the specific mechanism of action, the open pore structure provides an attachment and transmission channel for the capillary penetration of nano-scale chromium and nickel particles; the homogeneous matrix powder acts as a diffusion carrier to eliminate the interfacial thermal stress mismatch and ensure the integrity of the metallurgical bonding; the submicron closed pores generated by the controlled decomposition of magnesium carbonate not only release the sintering shrinkage stress, but also act as an inert gas phase barrier to block the deep penetration of the corrosive medium. This heterogeneous composite structure provides long-term passivation protection for Examples 1-3.

[0326] The fundamental reason for the performance degradation of Comparative Examples 1-8 is that each of them destroyed the synergistic chain of gradient pore structure, homogeneous matrix transmission and micropore stress buffering in Example 1: Comparative Example 1 lacks corrosion-resistant slurry, resulting in insufficient chromium diffusion concentration and discontinuous passivation film; Comparative Example 2 uses single-step high-pressure pressing to close the pores, cutting off the capillary penetration channel, and the corrosion-resistant components are only attached to the surface; after the homogeneous matrix powder is removed from Comparative Example 3, the thermal expansion mismatch between nano-Cr / Ni and the green matrix leads to interface cracking; Comparative Example 4 has excessive homogeneous powder to dilute the concentration of corrosion-resistant components, hindering the formation of continuous solid solution; Comparative Example 5 lacks magnesium carbonate decomposition, resulting in sintering shrinkage stress with nowhere to be released, inducing microcracks to penetrate the corrosion-resistant layer; Comparative Example 6 has excessive solvent residue carbonization and contaminates the grain boundaries, forming Fe3C / α-Fe micro-galvanic corrosion primary cells; Comparative Example 7 has too high a proportion of fine powder, which blocks the pore channels, destroys the gradient permeability and causes uneven component distribution; Comparative Example 8 does not activate the capillary action through low-pressure standing, and the slurry penetration depth is insufficient, resulting in an incomplete corrosion-resistant layer.

Claims

1. A method for preparing a corrosion-resistant high-strength iron-based alloy composite metal cabinet, characterized in that: The following steps are involved: Step (a) prepares iron-based alloy powder, which comprises, by mass percentage: C:0.01-0.05%， Cr:1.2-2.5%， Mo: 0.3-0.8%, V:0.1-0.3%， Balance Fe and unavoidable impurities; Step (b), pressing the iron-based alloy powder at a first pressure of 80-120 MPa to form a first green compact; Step (c), applying the corrosion-resistant reinforcing slurry to the surface of the first green body, standing it at 0.08-0.09 MPa for 1-2 minutes, then drying it at 40-60° C. under an inert atmosphere until the residual solvent content is ≤0.2 wt %, and performing a second pressing at a second pressure to obtain a second green body; The composition of the corrosion-resistant reinforcement slurry is as follows by mass percentage: Nano Cr powder: 10-20wt%, Nano Ni powder: 5-10wt%, Nano magnesium carbonate: 3-5wt%, Iron-based alloy powder: 25-35wt%, Binder: 1-2wt%, Dispersant: 0.1-0.3wt%, Solvent: balance; Step (d), sintering the second green body to obtain cabinet panels, and assembling and molding to obtain a corrosion-resistant high-strength iron-based alloy composite metal cabinet; The iron-based alloy powder of step (a) has a particle size of less than 80 μm, and a main particle size distribution of: 45-75μm particles account for 30±5wt%, 10-25 μm particles account for 50 ± 5 wt%; In step (d), the sintering process is as follows: The first stage: heat up to 300-400℃ at 1-3℃ / min and keep warm for 20-40min. The second stage: heat up to 1150-1200℃ at 4-6℃ / min and keep warm for 60-120min. The third stage: forced cooling to below 600°C, followed by air cooling to room temperature.

2. The method for preparing the corrosion-resistant high-strength iron-based alloy composite metal cabinet according to claim 1, characterized in that: The binder is polyvinyl butyral, the solvent is anhydrous ethanol, and the dispersant is ammonium polyacrylate.

3. The method for preparing the corrosion-resistant high-strength iron-based alloy composite metal cabinet according to claim 1, characterized in that: The amount of the corrosion-resistant enhancement slurry applied in step (c) is 0.5-0.8 g per square centimeter.

4. The method for preparing the corrosion-resistant high-strength iron-based alloy composite metal cabinet according to claim 1, characterized in that: The second pressure is 400-500 MPa.

5. The method for preparing the corrosion-resistant high-strength iron-based alloy composite metal cabinet according to claim 1, characterized in that: The forced cooling process of the third stage is: argon gas jet cooling, cooling rate ≥50℃ / min.

6. The method for preparing the corrosion-resistant high-strength iron-based alloy composite metal cabinet according to claim 1, characterized in that: The assembly forming method is welding, riveting or hinged connection, and the surface is coated with an anti-rust layer after the assembly is completed.

Images