A method for preparing a composite iron-based wear-resistant layer

Abstract

The present invention belongs to the field of ceramic phase reinforced iron-based composite materials, and specifically relates to a method for preparing a composite iron-based wear-resistant layer. The present invention adopts a cladding method to prepare a TiC and WC ceramic phase composite reinforced iron-based wear-resistant layer; the cladding method includes feeding main powder and auxiliary powder in sequence along the cladding direction. During cladding, the main powder forms a molten pool on the surface of the substrate to be clad, and the auxiliary powder falls to the rear of the molten pool; the main powder is composed of iron-based powder and TiC ceramic phase powder, and the auxiliary powder is WC ceramic phase powder. In the preparation method of the composite iron-based wear-resistant layer of the present invention, the WC ceramic phase of the powder fed later has a large density, and its powder feeding position is controlled to the rear of the molten pool, where the solidification speed of the molten pool is fast, which can prevent the WC ceramic phase from sinking to the bottom of the molten pool, thereby achieving a staggered and uniform distribution of the WC ceramic phase and the TiC ceramic phase in the wear-resistant layer, effectively solving the problem that the WC ceramic phase is easy to sink to the bottom during the cladding process, resulting in a decrease in wear resistance.

Description

Technical Field

[0001] The invention belongs to the field of ceramic phase reinforced iron-based composite materials, and particularly relates to a method for preparing a composite iron-based wear-resistant layer. Background Art

[0002] In many fields, including rail transit, oil and gas drilling, and infrastructure, mechanical components continue to face severe wear, resulting in significant losses. To reduce wear, methods such as cladding wear-resistant layers and cemented carbide inlays are being used to improve the wear resistance of mechanical components. Ceramic-reinforced wear-resistant layers are increasingly being used due to their cost-effectiveness. Plasma equipment, with its low cost and simple process, is widely used in the preparation of cladding layers. Therefore, research into the use of plasma processes to prepare high-performance, ceramic-reinforced wear-resistant layers holds great promise.

[0003] The performance of the ceramic phase-reinforced wear-resistant layer depends on the performance of the wear-resistant layer substrate, the size and content of the ceramic phase. When the hardness of the wear-resistant layer substrate is too high, its toughness is poor and it is easy to form peeling wear during the wear process; when the hardness of the wear-resistant layer substrate is too low, it wears too quickly under the action of abrasive particles, resulting in insufficient support for the ceramic phase, and the wear resistance is reduced after the ceramic phase falls off. The size and content of the ceramic phase also affect the performance of the wear-resistant layer. When the size is too large or the content is low, the gaps between the ceramic phases increase, and the wear-resistant layer substrate between the ceramic phases cannot be protected when fine abrasive particles act; when the size of the ceramic phase is too small, it cannot resist the impact of large-sized abrasive particles and is easy to peel off from the surface of the wear-resistant layer substrate, resulting in poor wear resistance.

[0004] Chinese invention patent application publication number CN107267909A discloses a plasma-sprayed Ni-based WC / TiC / LaAlO3 wear-resistant coating. The plasma spraying process produces a wear-resistant layer with high hardness and excellent wear resistance, composed of Ni60, WC powder, nano-TiC powder, and nano-LaAlO3 powder. While the addition of a NiCrAl transition layer improves the coating's adhesion, the overall thickness remains only 0.4 mm, and the combined content of WC and TiC ceramic phases does not exceed 30%, limiting further improvements in the coating's performance. Furthermore, the Ni-based coating exhibits high manufacturing costs. The coating exhibits poor wear resistance under varying operating conditions when subjected to abrasives of varying sizes, with significant fluctuations in wear resistance as the abrasive size changes. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a composite iron-based wear-resistant layer to solve the problems of WC ceramic phase easily sinking to the bottom during cladding, resulting in decreased wear resistance and large fluctuations in wear resistance when the abrasive particle size changes.

[0006] In order to achieve the above objectives, the technical solution adopted by the present invention is:

[0007] A method for preparing a composite iron-based wear-resistant layer, comprising: preparing a TiC and WC ceramic phase composite reinforced iron-based wear-resistant layer by a cladding method; the cladding method comprises feeding a main powder and an auxiliary powder in sequence along a cladding direction; during cladding, the main powder forms a molten pool on the surface of a substrate to be clad, and the auxiliary powder falls to the rear of the molten pool; the main powder comprises an iron-based powder and a TiC ceramic phase powder, and the auxiliary powder comprises a WC ceramic phase powder; the particle size of the TiC ceramic phase powder is smaller than that of the WC ceramic phase powder.

[0008] The preparation method of the composite iron-based wear-resistant layer of the present invention has the advantages that the TiC ceramic phase has a low density and is distributed in the upper middle part of the molten pool during the cladding process; the WC ceramic phase of the later-fed powder has a high density and will sink under the combined action of the powder feeding gas and gravity after entering the molten pool; the powder feeding position is controlled at the rear of the molten pool, where the molten pool solidifies quickly, and the WC ceramic phase can be prevented from sinking to the bottom of the molten pool, thereby achieving staggered and uniform distribution of the WC ceramic phase and the TiC ceramic phase in the wear-resistant layer, realizing composite strengthening, and effectively solving the problem that the WC ceramic phase is easy to sink to the bottom during the cladding process, resulting in reduced wear resistance.

[0009] This type of wear-resistant layer has good wear resistance when subjected to wear from abrasive particles of different sizes under different working conditions, avoiding large fluctuations in wear resistance of a single hard phase wear-resistant layer when the abrasive particle size changes.

[0010] Preferably, the particle size of the TiC ceramic phase powder is 5 to 180 μm, and the particle size of the WC ceramic phase powder is 50 to 400 μm. The design of a small-sized TiC ceramic phase and a large-sized WC ceramic phase is adopted. The large-sized WC ceramic plays the main role in resisting the impact of abrasive particles, preventing abrasive particles from directly impacting the small-sized TiC ceramic phase. At the same time, the WC ceramic phase utilizes the "shadow effect" to improve the wear resistance of the wear-resistant layer. The small-sized TiC ceramic phase is distributed in the middle of the large-sized WC ceramic phase, protecting the matrix between the WC ceramic phases, avoiding the matrix from wearing too quickly, resulting in insufficient bonding between the WC ceramic phase and the matrix, and a decrease in wear resistance after falling off. The two ceramic phase particles complement each other and form a composite reinforcement, thereby ensuring that the wear-resistant layer has good wear resistance when subjected to wear of abrasive particles of different sizes under different working conditions, avoiding large fluctuations in wear resistance of the single hard phase wear-resistant layer when the abrasive particle size changes.

[0011] In order to further optimize the wear resistance under different working conditions, it is further preferred that the particle size of the TiC ceramic phase powder is 5 to 50 μm, and the particle size of the WC ceramic phase powder is 100 to 400 μm.

[0012] Preferably, the mass of the TiC ceramic phase powder accounts for 20-50% of the mass of the iron-based powder, and the mass ratio of the TiC ceramic phase to the WC ceramic phase is (1-2):1. Controlling the TiC ceramic phase to the WC ceramic phase in this ratio optimizes the composite reinforcement and synergistic effect of the different types of ceramic phases, thereby improving the wear resistance of the wear-resistant layer.

[0013] Preferably, the iron-based powder is composed of the following components by mass percentage: 0.4-0.7% C, 0.3-0.7% Mn, 0.8-2.4% Si, 1.0-4.0% B, 15-18% Cr, 1.5-2.5% Ni, and the balance Fe. Using the iron-based powder to prepare the substrate provides a strong and balanced toughness, providing excellent support for the ceramic phase.

[0014] Preferably, the auxiliary powder delivery point is located behind the welding gun in the direction of movement, 2 to 9 mm from the center axis of the welding gun. The above-mentioned asynchronous powder delivery scheme can further optimize the staggered distribution of ceramic phases of different sizes and improve wear resistance.

[0015] The cladding objectives of the present invention can be achieved using either plasma cladding or laser cladding. Further preferably, the cladding is plasma cladding; during plasma cladding, the feed gas flow rate for the primary powder is 3-6 L / min, and the feed gas flow rate for the secondary powder is 2-4 L / min. Using these feed gas parameters ensures good process stability and significantly improves wear resistance.

[0016] Preferably, during the plasma cladding, the current is 120-180A, the distance from the substrate surface to be clad is 10-15mm, the ion gas flow rate is 2-5L / min, and the shielding gas flow rate is 5-15L / min. The above plasma cladding process parameters can further optimize the plasma cladding effect.

[0017] Preferably, the thickness of the composite reinforced iron-based wear-resistant layer is 3 to 5 mm. The large thickness design can maximize the advantages of the asynchronous powder feeding of the present invention, and the resulting wear-resistant layer can withstand harsh and complex wear-resistant working conditions, with good practical application effects.

[0018] Preferably, after cladding, the temperature is kept at not less than 200°C for 4 to 6 hours and then cooled with the furnace. The above-mentioned heat preservation treatment after cladding can reduce stress and further increase the service life of the wear-resistant layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a metallographic structure diagram of the composite iron-based wear-resistant layer of Example 1 of the present invention;

[0020] Figure 2 These are energy spectrum detection points of different ceramic phases in the metallographic structure of the composite iron-based wear-resistant layer of Example 1 of the present invention. DETAILED DESCRIPTION

[0021] The present invention provides a TiC and WC ceramic composite iron-based wear-resistant layer and its preparation method, addressing the issues of WC ceramic phases easily sinking to the bottom during plasma cladding, resulting in reduced wear resistance and insufficient bonding. Furthermore, a multi-scale TiC and WC ceramic phase design addresses the problem of large fluctuations in the wear-resistant layer's wear-resistant performance caused by varying abrasive particle size under different wear conditions.

[0022] The technical concept of the present invention is as follows: a plasma welding device with a double powder feeder is used, wherein the first powder feeder adds Fe-based powder material + small-sized TiC ceramic phase powder material, and the second powder feeder adds large-sized WC ceramic phase powder material. During the plasma coating process, the main powder feeder first feeds powder to form a molten pool on the surface of the substrate to be clad, and then the auxiliary powder feeder starts feeding powder, ensuring that the WC ceramic phase powder falls to the rear of the molten pool during the coating process. Through the above-mentioned coating method, the Fe-based powder material + small-sized TiC ceramic phase forms a molten pool as the main body of the cladding layer. The TiC ceramic phase has a low density and is distributed in the middle and upper part of the molten pool during the cladding process; the WC ceramic phase fed later has a high density and will sink after entering the molten pool under the combined action of the powder feeding gas and gravity. Therefore, its powder feeding position is controlled to the rear of the molten pool, where the molten pool solidifies quickly, which can prevent the WC ceramic phase from sinking to the bottom of the molten pool. Through the above-mentioned welding method, the preparation of composite wear-resistant layers of TiC and WC ceramic phases of different scales is achieved.

[0023] At the same time, strong, tough and balanced iron-based powder materials are selected to ensure their support for the ceramic phase. Large-sized WC ceramic phases and small-sized TiC ceramic phases are staggered and evenly distributed to achieve composite strengthening.

[0024] In order to optimize the bonding between the cladding layer and the substrate to be clad, the substrate to be clad is preferably preheated at 200-250° C. Before cladding, the substrate to be clad is subjected to conventional preparation work such as grinding away rust and burrs, and cleaning oil stains.

[0025] The iron-based powder, TiC ceramic phase powder, and WC ceramic phase powder are used after drying. Preferably, the drying temperature is 120° C. to 150° C., and the drying time is not less than 4 hours.

[0026] After the first powder feeder feeds powder, the second powder feeder starts feeding powder 1-3 seconds later.

[0027] After cladding, the workpiece is kept at a temperature not lower than 200°C for 4 to 6 hours to reduce stress. More preferably, the holding temperature is controlled at 200 to 290°C.

[0028] Furthermore, a composite wear-resistant layer composed of TiC and WC ceramic phases can be specifically prepared based on demand, enabling control over the size and content of the TiC and WC ceramic phases to ensure wear resistance and a good bond between the composite wear-resistant layer and the substrate. By adding the WC ceramic phase to the rear of the molten pool through a step-by-step powder feeding method, a simple and effective solution to the technical problem of WC ceramic phases easily sinking to the bottom of the molten pool due to their high density can be achieved, ensuring their uniform distribution within the wear-resistant layer structure.

[0029] The implementation process of the present invention is described in detail below with reference to specific embodiments.

[0030] 1. Specific embodiment of the method for preparing the composite iron-based wear-resistant layer of the present invention

[0031] Example 1

[0032] The method for preparing the composite iron-based wear-resistant layer of this embodiment comprises the following steps:

[0033] (1) Grind away rust and burrs on the surface of the workpiece to be welded, clean the oil stains, and then preheat at 260℃ for 2 hours. The workpiece to be welded is 35CrMo.

[0034] (2) The wear-resistant layer matrix powder material adopts iron-based powder with a particle size of 50-150 μm, and its element composition weight percentage (Wt%) is: C content is 0.5%, Mn content is 0.4%, Si content is 1.5%, B content is 3.0%, Cr content is 17%, Ni content is 2.0%, and the balance is Fe.

[0035] A 5-50 μm TiC ceramic phase (25% by weight) is added to the iron-based powder. The mixture is then dried and loaded into the first powder feeder. A 200-400 μm WC ceramic phase is dried and loaded into the second powder feeder. The TiC ceramic phase to WC ceramic phase ratio is controlled to be 25:15, and the total amount of TiC ceramic phase and WC ceramic phase added is 40% of the iron-based powder mass.

[0036] The powder material is dried at a temperature of 120°C to 150°C for at least 4 hours. In this example, the powder material is dried at 150°C for 4 hours.

[0037] (3) A plasma cladding process is used to prepare a wear-resistant layer on the surface of the preheated workpiece. During cladding, the first powder feeder first feeds powder, and the second powder feeder starts feeding powder 3 seconds later. The powder delivery point of the second powder feeder is located behind the moving direction of the welding gun and 7 mm away from the center axis of the welding gun. The thickness of the prepared wear-resistant layer is 3 to 5 mm. The plasma cladding process parameters are controlled as follows: current is 170A, 12 mm from the surface of the workpiece substrate, ion gas flow rate is 2.7 L / min, shielding gas flow rate is 12 L / min, powder delivery gas flow rate of the first powder feeder is 5 L / min, and powder delivery gas flow rate of the second powder feeder is 3.5 L / min. The ion gas, powder delivery gas and shielding gas are all argon. In actual operation, the distribution position of the WC ceramic phase in the wear-resistant layer is controlled by adjusting the powder delivery point of the second powder feeder, and the content of the WC ceramic phase is controlled by adjusting parameters such as the powder delivery speed.

[0038] (4) After the cladding is completed, the workpiece is placed in a heating furnace for insulation to reduce stress. The insulation temperature is 220°C. After 4 hours of insulation, it is cooled with the furnace to complete the cladding of the wear-resistant layer.

[0039] Examples 2 to 4

[0040] With reference to Example 1, the main process parameters of Examples 2 to 4 are listed in the following Table 1, and the parts not mentioned therein are consistent with those in Example 1.

[0041] Table 1 Preparation process parameters of composite iron-based wear-resistant layer of Examples 2 to 4

[0042]

[0043] Example 5

[0044] The method for preparing the composite iron-based wear-resistant layer of this embodiment comprises the following steps:

[0045] (1) The mass composition of the iron-based powder is: C 0.6%, Mn 0.4%, Si 1.2%, B 2.0%, Cr 16%, Ni 2.0%, and the balance is Fe. 30% of 50-100 μm TiC ceramic particles are added to the iron-based powder, dried, and mixed uniformly in a powder mixer at a temperature of 120°C for 4 hours, with a mixing time of not less than 2 hours. The dried powder is added to a first powder feeder; subsequently, dried 200-250 μm WC ceramic phase particles are fed to a second powder feeder.

[0046] (2) 34CrNiMo6 was used as the cladding substrate, its surface oil was cleaned and polished, and then the cladding substrate was preheated at a temperature of 220°C.

[0047] (3) A wear-resistant layer was prepared on the preheated workpiece surface using a laser cladding process. The laser cladding process parameters were as follows: laser cladding power of 4000 W, laser beam diameter of 3.5 mm, laser scanning speed of 3 mm / s, and argon shielding flow rate of 20 L / min. The powder feeding speed of the first powder feeder was 30 g / min, and the powder feeding speed of the second powder feeder was 10 g / min. The second powder feeder pipeline was adjusted to ensure that its landing point was located at the rear of the molten pool.

[0048] (4) After the cladding is completed, the workpiece is placed in a heating furnace at 250°C for insulation. After 4 hours of insulation, the heating is stopped and the workpiece is allowed to cool with the furnace. After reaching room temperature, it is taken out of the furnace to complete the preparation of the cladding layer.

[0049] 2. Experimental Examples

[0050] Experimental Example 1

[0051] The metallographic structure (thickness cross-section) of the composite iron-based wear-resistant layer obtained in Example 1 was analyzed, and the results were as follows: Figure 1 shown.

[0052] Depend on Figure 1 It can be seen that the large-sized WC ceramic phase and the small-sized TiC ceramic phase in the cladding layer are evenly staggered in the cladding layer, so that the reinforcing effects of the large-sized WC ceramic phase and the small-sized TiC ceramic phase can be exerted together.

[0053] Energy spectrum analysis is performed on different detection points in the metallographic structure. Figure 2 The results are shown in Table 2 below.

[0054] Table 2 Energy spectrum detection results of different ceramic phases

[0055]

[0056] Combined with the above energy spectrum analysis results, the existence and distribution of large-sized WC ceramic phase and small-sized TiC ceramic phase in the metallographic structure are further proved.

[0057] Experimental Example 2

[0058] This experimental example compares the anti-abrasive wear experiment of the WC cladding layer, the TiC cladding layer and the WC+TiC composite ceramic phase cladding layer of Example 1. A dry abrasive wear tester is used to perform a dry abrasive wear detection test (test conditions: loading force 100N, rotation speed 200r / min, total number of revolutions 6000s, quartz sand particle size of 50-70 mesh). The test results are shown in Table 3 below.

[0059] The WC cladding layer is prepared according to the method of Example 1. The first powder feeder feeds iron-based powder, and the second powder feeder feeds 200-400 μm WC ceramic phase powder. The proportion of WC ceramic phase powder to iron-based powder is controlled to be 40 wt.%, thereby obtaining a single WC cladding layer.

[0060] The TiC cladding layer is prepared according to the method of Example 1, by adding 40 wt.% of 5-50 μm TiC ceramic phase to the iron-based powder, and using only the first powder feeder to feed powder to obtain a single TiC cladding layer.

[0061] Table 3 Abrasive wear test performance of different cladding layers

[0062]

[0063] From the experimental results in Table 3, it can be seen that the WC cladding layer performs poorly in the wear resistance items of 10-20 mesh, 50-60 mesh, and 100-200 mesh. The mass loss in the 100-200 mesh item reaches 0.697g.

[0064] The TiC cladding layer has moderate performance in wear resistance at the three levels of 10-20 mesh, 50-60 mesh, and 100-200 mesh. Among them, the performance is the worst when subjected to 50-60 mesh abrasive wear. This may be related to the small particle size of the TiC ceramic phase, which cannot withstand the impact of larger abrasive particles.

[0065] Under the same total ceramic phase dosage, the WC+TiC composite cladding layer of Example 1 exhibited the best wear resistance at the 10-20 mesh, 50-60 mesh, and 100-200 mesh levels. It significantly outperformed the TiC cladding layer when subjected to wear from 50-60 mesh abrasive particles, demonstrating its adaptability to wear from particles of varying particle sizes. Due to the varying underground environments in different regions, abrasive particle sizes often vary significantly. The wear-resistant layer prepared using the method of the present invention can improve its adaptability to these particle size variations, enhancing wear resistance and thus extending the service life of wear-resistant components of tunneling machinery.

Claims

1. A method for preparing a composite iron-based wear-resistant layer, characterized in that: A TiC and WC ceramic phase composite reinforced iron-based wear-resistant layer is prepared by a cladding method; the cladding method includes successively feeding a main powder and an auxiliary powder along a cladding direction; during cladding, the main powder forms a molten pool on the surface of a substrate to be clad, and the auxiliary powder falls behind the molten pool; the main powder is composed of an iron-based powder and a TiC ceramic phase powder, and the auxiliary powder is a WC ceramic phase powder; the particle size of the TiC ceramic phase powder is 5 to 50 μm, and the particle size of the WC ceramic phase powder is 100 to 400 μm; the mass of the TiC ceramic phase powder is 20 to 50% of the mass of the iron-based powder, and the mass ratio of the TiC ceramic phase to the WC ceramic phase is (1 to 2):

1.

2. The method for preparing a composite iron-based wear-resistant layer according to claim 1, wherein: The iron-based powder is composed of the following components in mass percentage: C content of 0.4-0.7%, Mn content of 0.3-0.7%, Si content of 0.8-2.4%, B content of 1.0-4.0%, Cr content of 15-18%, Ni content of 1.5-2.5%, and the balance of Fe.

3. The method for preparing a composite iron-based wear-resistant layer according to claim 1, wherein: The auxiliary powder feeding drop point is located behind the moving direction of the welding gun and is 2 to 9 mm away from the central axis of the welding gun.

4. The method for preparing a composite iron-based wear-resistant layer according to claim 3, wherein: The cladding is plasma cladding; during the plasma cladding, the powder feeding gas flow rate of the main powder is 3 to 6 L / min, and the powder feeding gas flow rate of the auxiliary powder is 2 to 4 L / min.

5. The method for preparing a composite iron-based wear-resistant layer according to claim 4, wherein: During the plasma cladding, the current is 120-180A, the distance from the surface of the substrate to be clad is 10-15 mm, the ion gas flow rate is 2-5 L / min, and the shielding gas flow rate is 5-15 L / min.

6. The method for preparing a composite iron-based wear-resistant layer according to claim 1, wherein: The thickness of the composite reinforced iron-based wear-resistant layer is 3 to 5 mm.

7. The method for preparing a composite iron-based wear-resistant layer according to claim 1 or 6, characterized in that: After cladding, keep the temperature at no less than 200℃ for 4 to 6 hours and cool with the furnace.

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