A wear-resistant centrifugal pump impeller and its preparation method

Abstract

The present invention relates to the technical field of centrifugal pumps, and in particular to a wear-resistant centrifugal pump impeller and a preparation method thereof. A preparation method for a wear-resistant centrifugal pump impeller, the method comprising the following steps: 1) pre-setting an alloyed powder layer on the surface of an impeller substrate, wherein the thickness of the powder layer is 0.3-0.5 mm; 2) using a high-power laser to scan and melt the pre-set powder, with a protective air flow rate of 10-20 L / min during the scanning process; 3) controlling the laser scanning power to 1.5-3 kW, the scanning speed to 100-300 mm / min, and the overlap rate to 25-35%, so that the alloyed layer forms a metallurgical bond with the impeller substrate; and forming a fine dendrite structure and a high-hardness ceramic phase in the obtained alloyed layer after cooling. The method improves the wear resistance and corrosion resistance of the surface of the centrifugal pump impeller through a laser alloying process.

Description

Technical Field

[0001] The present invention relates to the technical field of centrifugal pumps, and in particular to a wear-resistant centrifugal pump impeller and a preparation method thereof. Background Art

[0002] Centrifugal pumps are widely used in industries such as petrochemicals, pharmaceuticals, and food processing. They are typically used to transport fluids containing solid particles, corrosive media, or high-temperature media. As a core component, the impeller of a centrifugal pump is subject to severe wear and corrosion during long-term use. The main failure modes include:

[0003] 1. Abrasive wear: Solid particles in the fluid wash the impeller surface at high speed with the medium, causing the surface layer of the material to peel off;

[0004] 2. Corrosion and wear: Chemical media corrode the material surface under high temperature or strong acid / alkali conditions, weakening the wear resistance;

[0005] 3. Fatigue wear: surface crack expansion and material fatigue failure caused by long-term high-speed rotation.

[0006] While traditional impeller materials (such as 304 and 316 stainless steel) have a certain degree of corrosion resistance, their low hardness makes them difficult to meet service life requirements in high-wear or complex corrosive environments. Therefore, improving the hardness, wear resistance, and corrosion resistance of the impeller surface has become an important research direction for extending the service life of centrifugal pumps. Existing technologies mainly improve impeller performance through the following methods, but each has certain limitations:

[0007] 1. Surface heat treatment: Although methods such as carburizing and nitriding can improve surface hardness, they are prone to failure in corrosive media, and the processing temperature is high, and the workpiece is prone to deformation;

[0008] 2. Coating technology: such as thermal spraying and electroplating processes can form a wear-resistant layer on the surface, but the bonding strength is low and it is easy to peel off under high load or impact conditions;

[0009] 3. Integral alloying materials: such as titanium alloy or high-hardness integral materials, although they have excellent wear resistance, are expensive and difficult to process, with poor economy and feasibility.

[0010] The above technical methods cannot take into account the needs of high wear resistance, corrosion resistance and economy. In recent years, laser alloying technology has gradually become an important means to improve the surface performance of metals due to its high energy density and high processing precision. However, the existing laser alloying technology still has the following problems in material design and process optimization: 1. Insufficient selection of alloying materials: Existing laser alloying materials are mostly based on a single function, and lack the coordinated optimization design of the hard phase and the matrix toughness phase. 2. Poor structural uniformity: Rapid solidification of the molten pool may lead to uneven distribution of the hard phase, affecting the consistency of surface performance. 3. Unstable control of process parameters: Parameters such as laser power and scanning speed have a significant impact on surface quality. Existing research is mostly based on experience and lacks systematic optimization. Summary of the Invention

[0011] In view of the deficiencies in the prior art, the present invention provides a method for preparing a wear-resistant centrifugal pump impeller, which improves the wear resistance and corrosion resistance of the surface of the centrifugal pump impeller through a laser alloying process.

[0012] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0013] A method for preparing a wear-resistant centrifugal pump impeller, the method comprising the following steps:

[0014] 1) Pre-depositing an alloyed powder layer on the surface of the impeller substrate, wherein the thickness of the powder layer is 0.3-0.5 mm; the pre-deposited alloyed powder includes the following components and mass percentages:

[0015] Tungsten carbide 25-35%, titanium carbide 8-15%, boron carbide 3-8%;

[0016] Cobalt-based alloy powder 20-35%, nickel-based alloy powder 5-15%;

[0017] Rare earth elements 3-8%;

[0018] Lubricating phase MoS23-8%, Al2O33-8%;

[0019] Active elements B1-5%, Si1-5%;

[0020] 2) Use a high-power laser to scan and melt the pre-set powder, with a protective gas flow rate of 10–20 L / min during the scanning process;

[0021] 3) Control the laser scanning power to 1.5–3 kW, the scanning speed to 100–300 mm / min, and the overlap ratio to 25–35% to form a metallurgical bond between the alloyed layer and the impeller substrate; and form a fine dendrite structure and a high-hardness ceramic phase in the resulting alloyed layer after cooling.

[0022] Preferably, the pre-alloyed powder comprises the following components and mass percentages:

[0023] Tungsten carbide 28-32%, titanium carbide 10-12%, boron carbide 4-6%;

[0024] Cobalt-based alloy powder 25-32%, nickel-based alloy powder 8-12%;

[0025] Rare earth elements 4-6%;

[0026] Lubricating phase MoS24-6%, Al2O34-6%;

[0027] Active elements B2-4%, Si2-4%.

[0028] Preferably, the rare earth elements include Y2%, Ce2%, and Nd1%.

[0029] Preferably, the average particle size of the tungsten carbide, titanium carbide and boron carbide is 1-5 μm, so as to enhance the bonding strength with the matrix material and refine the grains.

[0030] Preferably, the cobalt-based alloy powder is composed of the following alloy raw materials: cobalt (Co): 40-60%, chromium (Cr): 25-35%, molybdenum (Mo): 5-10%, iron (Fe): 2-5%, carbon (C): 0.5-2%, silicon (Si): 0.5-1%, tungsten (W): 1-3%; the nickel-based alloy powder is composed of the following alloy raw materials: nickel (Ni): 50-65%, chromium (Cr): 20-30%, iron (Fe): 5-15%, molybdenum (Mo): 3-10%, aluminum (Al): 1-2%, titanium (Ti): 1-2%, carbon (C): 0.1-0.5%, and boron (B): 0.1-0.3%.

[0031] Preferably, a rectangular spot is used during the laser melting, and the spot width is within the range of 8-12 mm. A real-time temperature monitoring system is combined to dynamically adjust the laser power to ensure the thickness of the alloyed layer and the uniformity of the structure.

[0032] Preferably, a gradient alloying layer structure is formed by performing secondary laser scanning or multiple lamination processes on the high wear area of ​​the impeller, so that the area has higher hardness and better toughness.

[0033] Furthermore, the present invention also provides a centrifugal pump impeller prepared by the method.

[0034] The present invention further provides an alloyed powder composition for preparing the centrifugal pump impeller, wherein the alloyed powder comprises the following components and mass percentages:

[0035] Tungsten carbide 25-35%, titanium carbide 8-15%, boron carbide 3-8%;

[0036] Cobalt-based alloy powder 20-35%, nickel-based alloy powder 5-15%;

[0037] Rare earth elements 3-8%;

[0038] Lubricating phase MoS23-8%, Al2O33-8%;

[0039] Active elements B1-5%, Si1-5%.

[0040] Preferably, the cobalt-based alloy powder is composed of the following alloy raw materials: cobalt (Co): 40-60%, chromium (Cr): 25-35%, molybdenum (Mo): 5-10%, iron (Fe): 2-5%, carbon (C): 0.5-2%, silicon (Si): 0.5-1%, tungsten (W): 1-3%; the nickel-based alloy powder is composed of the following alloy raw materials: nickel (Ni): 50-65%, chromium (Cr): 20-30%, iron (Fe): 5-15%, molybdenum (Mo): 3-10%, aluminum (Al): 1-2%, titanium (Ti): 1-2%, carbon (C): 0.1-0.5%, boron (B): 0.1-0.3%.

[0041] By adopting the above-mentioned technical solution, the present invention realizes a significant performance improvement of the centrifugal pump impeller under high wear and high corrosion conditions through the alloying material formula and optimized laser alloying process. The specific technical effects are as follows:

[0042] 1. Improved wear resistance: By introducing high-hardness particles such as tungsten carbide (WC), titanium carbide (TiC), and boron carbide (B4C), a uniformly distributed composite hard layer is formed, achieving a microhardness of HV1000–HV1200. This improves wear resistance by more than six times compared to untreated impellers. Furthermore, during the laser melting process, the hard phase particles form a strong metallurgical bond with the substrate, significantly reducing hard phase spalling and improving durability.

[0043] 2. Enhanced Corrosion Resistance: The alloyed layer contains cobalt-based and nickel-based alloy powders, whose high chromium content (20–35%) improves oxidation and pitting resistance. Molybdenum (Mo) further enhances the alloyed layer's corrosion resistance in saltwater, acidic, and alkaline media. The addition of rare earth elements (yttrium, cerium, and neodymium) not only refines the grain size but also significantly reduces the risk of intergranular corrosion, reducing the corrosion rate by over 50%.

[0044] 3. Improved High-Temperature Stability: The addition of cobalt (Co), nickel (Ni), and tungsten (W) to the alloying layer provides excellent high-temperature strength, enabling the impeller to maintain structural stability and wear resistance in high-temperature media up to 500°C. The lubricating phase, molybdenum sulfide (MoS2), exhibits a low coefficient of friction at high temperatures, reducing heat buildup and frictional losses under dynamic operating conditions.

[0045] 4. Microstructure Optimization: The laser alloying process forms a fine dendrite structure and uniformly distributed carbide phase, effectively avoiding the brittleness caused by a large grain structure. The gradient hardness of the alloy layer gradually transitions from the surface to the inside, reducing the thermal stress difference between the alloy layer and the substrate, significantly improving fatigue resistance.

[0046] In summary, compared to impellers made of overall high-performance materials, the present invention only performs laser alloying treatment on the impeller surface, saving the use of a large amount of high-performance materials and reducing costs by more than 30%. The laser alloying process uses real-time temperature control and dynamic power regulation technology to ensure the consistency of the quality of the alloyed layer on the large-area impeller surface, while improving the processing efficiency by 20% compared to traditional surface heat treatment. When the treated centrifugal pump impeller operates in complex corrosive media (such as salt water, acidic or alkaline fluids), its service life is extended by more than 4 times that of the untreated impeller. Under high-load and high-speed operation conditions in a fluid medium containing solid particles, the wear resistance of the impeller surface is significantly improved, reducing the frequent replacement due to wear. DETAILED DESCRIPTION

[0047] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with 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. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0048] Example 1

[0049] Alloying material formula:

[0050] Tungsten carbide (WC) 30%, titanium carbide (TiC) 10%, boron carbide (B4C) 5%;

[0051] Cobalt-based alloy powder 30% (composition: cobalt 50%, chromium 30%, molybdenum 10%, iron 5%, carbon 1%, silicon 1%, tungsten 3%);

[0052] Nickel-based alloy powder 10% (composition: nickel 60%, chromium 25%, iron 10%, molybdenum 3%, aluminum 1%, titanium 1%);

[0053] Rare earth elements (yttrium 2%, cerium 2%, neodymium 1%) totaling 5%;

[0054] Lubricating phase: molybdenum sulfide (MoS2) 3%, aluminum oxide (Al2O3) 2%;

[0055] Active elements boron (B) 3%, silicon (Si) 2%.

[0056] Preparation process:

[0057] Impeller base: 304 stainless steel;

[0058] Alloy material pre-coating thickness: 0.4 mm;

[0059] Laser power: 2.0 kW; scanning speed: 200 mm / min; overlap rate: 30%;

[0060] Protective gas: high-purity argon, flow rate 15 L / min;

[0061] Melting spot width: 10 mm.

[0062] Example 2

[0063] Alloying material formula:

[0064] Tungsten carbide (WC) 28%, titanium carbide (TiC) 12%, boron carbide (B4C) 5%;

[0065] Cobalt-based alloy powder 25%, nickel-based alloy powder 10%;

[0066] Rare earth elements 5%;

[0067] Lubricating phase: molybdenum sulfide (MoS2) 2%, aluminum oxide (Al2O3) 3%;

[0068] Active elements boron (B) 4%, silicon (Si) 6%.

[0069] The preparation process is referred to Example 1.

[0070] Example 3

[0071] Alloying material formula:

[0072] Tungsten carbide (WC) 32%, titanium carbide (TiC) 10%, boron carbide (B4C) 6%;

[0073] Cobalt-based alloy powder 28%, nickel-based alloy powder 9%;

[0074] Rare earth elements 5%;

[0075] Lubricating phase: molybdenum sulfide (MoS2) 2%, aluminum oxide (Al2O3) 3%;

[0076] Active elements boron (B) 2%, silicon (Si) 3%.

[0077] The preparation process is referred to Example 1.

[0078] Comparative Example 1

[0079] Use untreated 304 stainless steel impeller.

[0080] Comparative Example 2

[0081] The impeller is electroplated with nickel-phosphorus coating, thickness 0.3 mm.

[0082] Comparative Example 3

[0083] The impeller surface is carburized and the hardened layer thickness is 0.2 mm.

[0084] Comparative Example 4

[0085] Alloying material formula:

[0086] Tungsten carbide (WC) 45%;

[0087] Cobalt-based alloy powder 30%;

[0088] Nickel-based alloy powder 10%;

[0089] Rare earth elements total 5%;

[0090] Lubricating phase: molybdenum sulfide (MoS2) 3%, aluminum oxide (Al2O3) 2%;

[0091] Active elements boron (B) 3%, silicon (Si) 2%.

[0092] The preparation process is referred to Example 1.

[0093] Comparative Example 5

[0094] Tungsten carbide (WC) 30%, titanium carbide (TiC) 10%, boron carbide (B4C) 5%;

[0095] Cobalt-based alloy powder 40% (

[0096] Rare earth elements (yttrium 2%, cerium 2%, neodymium 1%) totaling 5%;

[0097] Lubricating phase: molybdenum sulfide (MoS2) 3%, aluminum oxide (Al2O3) 2%;

[0098] Active elements boron (B) 3%, silicon (Si) 2%.

[0099] The preparation process is referred to Example 1.

[0100] In order to verify the technical effect of the present invention, the present invention conducted comparative tests on the preparation and performance of the impellers of the embodiment and the comparative example, focusing on evaluating the following performance indicators: microhardness, wear resistance, corrosion resistance, and service life. The experimental process is as follows:

[0101] 1. Experimental Preparation

[0102] 1) Sample preparation

[0103] Examples 1-3: Laser alloying treatment is performed according to the corresponding alloying material formula and preparation process.

[0104] Comparative Example 1: An untreated 304 stainless steel impeller was used.

[0105] Comparative Example 2: Electroplated nickel-phosphorus coating with a coating thickness of 0.3 mm.

[0106] Comparative Example 3: Carburizing treatment was adopted, and the thickness of the carburized layer was 0.2 mm.

[0107] Comparative Examples 4-5: Laser alloying treatment was performed according to the respective alloying material formulations and the preparation process of Example 1.

[0108] 2) Experimental equipment

[0109] Laser processing equipment: high-power fiber laser (maximum power 5 kW).

[0110] Performance testing equipment: microhardness tester, wear resistance testing machine, corrosion testing equipment.

[0111] Test medium: fluid containing solid particles (5% sand-water suspension), 3.5% NaCl solution.

[0112] 2. Test Method

[0113] 1) Microhardness test

[0114] Use a microhardness tester to conduct multiple point tests on the surface of the laser alloying layer and take the average value.

[0115] 2) Wear resistance test

[0116] The impeller surface was subjected to friction and wear tests on a wear testing machine using a sand-water suspension as the medium, and the wear volume (unit: mm³) was recorded.

[0117] 3) Corrosion resistance test

[0118] The impeller was immersed in 3.5% NaCl solution and subjected to a salt spray corrosion test. The corrosion rate after 24 hours was measured (unit: mg / cm²·h).

[0119] 4) Service life test

[0120] The centrifugal pump is tested at high speed in a sand-containing fluid medium, simulating actual working conditions. The time required to reach failure conditions (such as surface wear and crack propagation) is recorded.

[0121] The experimental results are shown in the following table:

[0122] sample Microhardness (HV) Wear volume (mm³) Corrosion rate (mg / cm²·h) Service life (hours) Example 1 1050 0.18 0.05 2500 Example 2 1100 0.15 0.04 2700 Example 3 1150 0.13 0.03 3000 Comparative Example 1 200 1.50 0.30 500 Comparative Example 2 500 0.80 0.20 1000 Comparative Example 3 750 0.60 0.18 1500 Comparative Example 4 950 0.25 0.06 2000 Comparative Example 5 1050 0.22 0.05 2200

[0123] Experimental results analysis

[0124] 1. Microhardness

[0125] The microhardness of Example 3 is the highest, HV1150, which is better than the other examples and all comparative examples. The hardness of the untreated impeller of Comparative Example 1 is the lowest, only HV200, which is not good.

[0126] 2. Wear resistance

[0127] The wear volume of the impellers in the examples is significantly lower than that in the comparative examples, especially in Example 3, which has a wear volume of 0.13 mm³, which is superior to the other samples. Comparative Example 1 has the largest wear volume (1.50 mm³), indicating the worst anti-wear performance.

[0128] 3. Corrosion resistance

[0129] Example 3 had the lowest corrosion rate (0.03 mg / cm²·h), demonstrating excellent corrosion resistance. Comparative Example 1 had the highest corrosion rate (0.30 mg / cm²·h), demonstrating that its surface was susceptible to failure in corrosive media.

[0130] 4. Service life

[0131] The service life of Example 3 is the longest, reaching 3000 hours, which is better than all the examples and comparative examples. The service life of Comparative Example 1 is only 500 hours, which is significantly lower than that of other samples.

[0132] Through the above experimental process and data comparison, the embodiments of the present invention significantly improved the microhardness, wear resistance, corrosion resistance, and service life of the centrifugal pump impeller. Compared with the existing technology, Example 3 performed the best, especially under high-wear and high-corrosion conditions, with comprehensive performance significantly superior to all comparative examples. This demonstrates the superiority and practical application value of the technical solution of the present invention.

[0133] The above is a description of the embodiments of the present invention. The above description of the disclosed embodiments will enable professionals in the field to implement or use the present invention. Various modifications to these embodiments will be apparent to professionals in the field. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a wear-resistant centrifugal pump impeller, characterized in that: The method comprises the following steps: 1) Pre-deposit an alloyed powder layer on the surface of the impeller substrate, wherein the thickness of the powder layer is 0.3-0.5 mm; the pre-deposited alloyed powder comprises the following components and mass percentages: Tungsten carbide 25-35%, titanium carbide 8-15%, boron carbide 3-8%; Cobalt-based alloy powder 20-35%, nickel-based alloy powder 5-15%; Rare earth elements 3-8%; Lubricating phase MoS23-8%, Al2O33-8%; Active elements B1-5%, Si1-5%; The cobalt-based alloy powder is composed of the following alloy raw materials: cobalt (Co): 40-60%, chromium (Cr): 25-35%, molybdenum (Mo): 5-10%, iron (Fe): 2-5%, carbon (C): 0.5-2%, silicon (Si): 0.5-1%, tungsten (W): 1-3%, and the sum of the components of the cobalt-based alloy powder is 100%; the nickel-based alloy powder is composed of the following alloy raw materials: nickel (Ni): 50-65%, chromium (Cr): 20-30%, iron (Fe): 5-15%, molybdenum (Mo): 3-10%, aluminum (Al): 1-2%, titanium (Ti): 1-2%, carbon (C): 0.1-0.5%, boron (B): 0.1-0.3%, and the sum of the components of the nickel-based alloy powder is 100%; rare earth elements include Y2%, Ce2%, and Nd1%. 2) Use a high-power laser to scan and melt the pre-set powder, with a protective gas flow rate of 10–20 L / min during the scanning process; 3) Control the laser scanning power to 1.5–3 kW, the scanning speed to 100–300 mm / min, and the overlap ratio to 25–35% to form a metallurgical bond between the alloyed layer and the impeller substrate; and form a fine dendrite structure and a high-hardness ceramic phase in the resulting alloyed layer after cooling.

2. The method for preparing a wear-resistant centrifugal pump impeller according to claim 1, characterized in that: The pre-alloyed powder consists of the following components and mass percentages: Tungsten carbide 28-32%, titanium carbide 10-12%, boron carbide 4-6%; Cobalt-based alloy powder 25-32%, nickel-based alloy powder 8-12%; Rare earth elements 4-6%; Lubricating phase MoS24-6%, Al2O34-6%; Active elements B2-4%, Si2-4%.

3. The method for preparing a wear-resistant centrifugal pump impeller according to claim 1 or 2, characterized in that: The average particle size of the tungsten carbide, titanium carbide and boron carbide is 1-5 μm.

4. The method according to claim 1, wherein A rectangular spot is used during scanning melting, with a spot width in the range of 8–12 mm. A real-time temperature monitoring system is combined to dynamically adjust the laser power to ensure the thickness and structural uniformity of the alloying layer.

5. The method according to claim 1, wherein By performing secondary laser scanning or multiple lamination processes on the high wear area of ​​the impeller, a gradient alloying layer structure is formed, so that the area has higher hardness and better toughness.

6. A centrifugal pump impeller prepared by the method according to any one of claims 1 to 5.

7. An alloyed powder composition for preparing a centrifugal pump impeller, characterized in that: The alloying powder includes the following components and mass percentages: Tungsten carbide 25-35%, titanium carbide 8-15%, boron carbide 3-8%; Cobalt-based alloy powder 20-35%, nickel-based alloy powder 5-15%; Rare earth elements 3-8%; Lubricating phase MoS23-8%, Al2O33-8%; Active elements B1-5%, Si1-5%; The cobalt-based alloy powder is composed of the following alloy raw materials: cobalt (Co): 40-60%, chromium (Cr): 25-35%, molybdenum (Mo): 5-10%, iron (Fe): 2-5%, carbon (C): 0.5-2%, silicon (Si): 0.5-1%, tungsten (W): 1-3%, and the sum of the components of the cobalt-based alloy powder is 100%; the nickel-based alloy powder is composed of the following alloy raw materials: nickel (Ni): 50-65%, chromium (Cr): 20-30%, iron (Fe): 5-15%, molybdenum (Mo): 3-10%, aluminum (Al): 1-2%, titanium (Ti): 1-2%, carbon (C): 0.1-0.5%, boron (B): 0.1-0.3%, and the sum of the components of the nickel-based alloy powder is 100%; rare earth elements include Y2%, Ce2%, and Nd1%.