Process for manufacturing a wear-resistant brake drum

Abstract

The application provides a preparation process of a wear-resistant brake drum and belongs to the technical field of aluminum-based alloy materials, and comprises the following steps: sequentially preparing a composite material, a multi-element aluminum alloy shell and a composite brake drum blank; finally, the composite brake drum blank is preheated, laser cladding is performed on a gray cast iron base to form a Ni625 layer, laser cladding is performed on the surface of the Ni625 layer using a Ni50 / hBN composite powder to form a Ni50 / hBN layer, heat preservation is performed, and cooling is performed to room temperature, so that the wear-resistant brake drum is obtained. The application can improve the overall strength and toughness and has good wear resistance.

Description

Technical Field

[0001] This invention relates to the field of aluminum-based alloy materials technology, and specifically to a manufacturing process for a wear-resistant brake drum. Background Technology

[0002] With the continuous development of automotive technology and the improvement of road traffic conditions, vehicle speeds are constantly increasing, vehicle load-bearing capacity is continuously strengthening, and driving environments are becoming more complex and demanding. Especially under conditions of high speed, heavy load, and frequent braking, the frequency of braking and emergency braking increases significantly, directly driving higher requirements for braking system performance. As a key component, the brake drum's material properties directly affect the vehicle's braking effect and safety during long-term use. Traditional brake drums, under high-speed and heavy-load operating conditions, often exhibit problems such as insufficient hardness and poor wear resistance, leading to accelerated surface wear, weakened braking effect, and shortened service life. This affects the vehicle's braking safety and makes it difficult to meet the requirement of a service life exceeding 30,000 kilometers under high-speed, heavy-load, and frequent braking conditions.

[0003] To improve the performance and extend the service life of brake drums, Chinese patent application CN113458363A discloses a bimetallic iron-iron composite brake drum and its manufacturing method. This method uses high-strength ductile iron or high-strength vermicular graphite cast iron as the outer layer and wear-resistant gray cast iron as the inner layer, enhancing the overall material properties through a metallurgical bonding process. However, despite the metallurgical bonding method between the outer ductile iron or vermicular graphite cast iron layer and the inner wear-resistant gray cast iron layer of this bimetallic iron-iron composite brake drum, the wear resistance of the working surface, the stability of the interface bonding, and the thermal fatigue crack resistance are still insufficient under high-speed, heavy-load, and frequent thermal cycling conditions. This may lead to accelerated wear, interface weakening, or peeling, thus affecting braking performance and service life. Even with the metallurgical bonding method, factors such as high temperature, frictional load, and thermal expansion mismatch can still cause metallurgical interface peeling or weakening, thus affecting the overall performance of the brake drum.

[0004] In addition, aluminum alloy brake drums are commonly used in existing technologies to achieve weight reduction, thereby improving fuel efficiency and reducing vehicle weight. To enhance strength and toughness, conventional aluminum alloy brake drums typically incorporate zinc, magnesium, or silicon alloys to strengthen the aluminum alloy, promoting solid solution strengthening or precipitation strengthening. However, the addition of these alloying elements often introduces several problems: First, increased hardness may lead to increased brittleness, making the aluminum alloy prone to cracking or fracture under high temperature and frequent braking conditions. Second, the high coefficient of thermal expansion of aluminum alloys, which does not match the coefficients of thermal expansion of the alloying elements, easily leads to thermal stress concentration during thermal cycling, resulting in cracks and deformation. Furthermore, conventional aluminum alloys have poor thermal fatigue resistance, making them susceptible to microcrack propagation under rapid cooling and heating thermal cycling loads, thus affecting the service life of the brake drum. Simultaneously, although the addition of magnesium, zinc, and other alloying elements can increase the hardness of aluminum alloys, the improvement in wear resistance is limited; the aluminum alloy surface is still prone to wear, especially under high load and frequent braking conditions, where insufficient wear resistance leads to decreased braking performance.

[0005] Therefore, there is a need to provide a manufacturing process for wear-resistant brake drums to solve the problems existing in the prior art. Summary of the Invention

[0006] In view of this, the present invention provides a manufacturing process for a wear-resistant brake drum, which can improve the overall strength and toughness while having good wear resistance.

[0007] To achieve the above objectives, the present invention provides a manufacturing process for a wear-resistant brake drum, comprising the following steps:

[0008] S1. Mix and stir high-entropy alloy powder, aluminum powder, Sn powder and magnesium powder, perform discharge plasma sintering under argon atmosphere, pressurize, heat up, vacuum diffuse, cool, crush and sieve, and preheat to obtain composite material.

[0009] S2. Add aluminum ingots to a graphite crucible, then add zinc ingots, magnesium ingots, and metallic calcium particles in sequence. Heat and melt the mixture, keep it warm, then add Al-5Ti-1B intermediate alloy and stir. Refine and degas, remove slag, add composite material and continue stirring, let it stand, degas, cast into shape, clean and polish to obtain a multi-element aluminum alloy shell.

[0010] S3. After cleaning and drying the inner cavity of the multi-element aluminum alloy shell, add a modified protective agent, rotate to spread the modified protective agent on the inner surface to form a continuous covering layer, increase the speed, pour in gray cast iron to form a gray cast iron base in the inner cavity, spray water mist to cool and solidify, and obtain a composite brake drum blank.

[0011] S4. The composite brake drum blank is preheated and laser clad onto a gray cast iron substrate to form a Ni625 layer. Then, Ni50 / hBN composite powder is used to laser clad onto the surface of the Ni625 layer to form a Ni50 / hBN layer. The blank is kept at a certain temperature and then cooled to room temperature to obtain a wear-resistant brake drum.

[0012] Unlike conventional methods that directly add multiple elemental metal powders to molten aluminum, this invention prioritizes the discharge plasma sintering of high-entropy alloy powder and aluminum powder under an argon atmosphere. Under pressure and temperature conditions, the aluminum powder softens and plastically flows, forming an aluminum-based coating on the surface of the high-entropy alloy particles. Simultaneously, trace amounts of Sn form a transient wetting phase in the sintering temperature range, promoting the spreading and coating of the aluminum phase on the surface of the high-entropy alloy particles and improving interparticle connectivity and densification. Magnesium powder has a certain film-breaking and deoxidizing effect on the oxide film on the powder surface, thereby further improving the wetting and interfacial bonding quality of the aluminum phase on the high-entropy alloy particles. Subsequently, the sintered body is transferred to a vacuum diffusion furnace for diffusion treatment, allowing elemental interdiffusion between the aluminum phase and the high-entropy alloy phase at the interface to form a continuous metallurgical bonding transition zone, thus producing a core-shell structured composite material with high-entropy alloy particles as the core and an aluminum-based coating layer as the shell.

[0013] Because the outer aluminum-based cladding layer of the core-shell structure is homologous and of the same phase as the molten aluminum, the outer cladding phase preferentially fuses with the melt after the composite material is added, forming a continuous transition interface. This prevents the high-entropy alloy reinforcing phase from directly contacting the melt as exposed particles, reducing the risk of repulsion, floating, and agglomeration caused by surface oxide film and interfacial tension differences. Simultaneously, the aluminum-based shell acts as an isolation and pre-dispersion layer for the core, reducing inclusions, gas entrapment, and other defect sources, and weakening the abrupt interface changes and local component enrichment tendencies between the high-entropy alloy and the matrix material. This reduces the possibility of severe local reactions and the formation of coarse, brittle intermetallic compounds, thereby improving the bonding strength and density of the as-cast structure. Furthermore, due to the high interfacial bonding strength of the core-shell structure particles and the ability of the shell layer to achieve stress relief and plastic coordination, under dynamic loads, it helps improve load transfer efficiency, inhibit matrix interface debonding and microcrack initiation, and reduce the micro-damage accumulation rate through crack deflection / passivation. This enhances the fatigue and impact failure resistance of the aluminum-based composite material, while simultaneously improving overall toughness.

[0014] This invention employs laser cladding deposition of a Ni625 layer and a Ni50 / hBN layer on the surface of a gray cast iron substrate to form a composite wear-resistant surface layer system. The Ni625 layer serves as a transition layer between the gray cast iron substrate and the Ni50 / hBN layer. This allows the melting and dilution of the gray cast iron substrate during the cladding process to primarily occur within the buffer layer, thereby reducing the disturbance of Fe, C, and other components in the gray cast iron to the composition and microstructure of the Ni50 / hBN layer. This reduces embrittlement and crack sensitivity caused by compositional deviations and local microstructural abrupt changes in the Ni50 / hBN layer, lowers the probability of microcrack / porosity defect channel formation, reduces the risk of oxidizing medium penetration and repeated oxide film rupture, and improves high-temperature oxidation stability and thermal fatigue life. Simultaneously, Ni625 possesses good toughness and high-temperature stability, which can alleviate the thermophysical property mismatch between the gray cast iron substrate and the Ni50 / hBN layer under thermal cycling and reduce the peak residual tensile stress, improving the stability of the interlayer metallurgical bond. This further reduces the risk of thermal cracking and spalling, providing a reliable load-bearing foundation for the Ni50 / hBN layer.

[0015] With the Ni625 layer providing a stable bond and load-bearing foundation, the Ni50 / hBN layer uses Ni50 nickel-based alloy as its framework, leveraging its high hardness and reinforcing phase support to improve resistance to abrasive wear and plastic deformation. Simultaneously, hBN, a layered solid lubricating phase, easily slides along the interlayer during friction, forming a lubricating transfer film on the contact surface. This reduces the coefficient of friction and adhesive wear tendency, and decreases frictional heat accumulation, thereby inhibiting the propagation of surface microcracks and the formation of spalling. Because the Ni625 layer reduces the dilution effect of the gray cast iron substrate on the Ni50 / hBN layer and improves the interfacial bonding strength, the hard load-bearing and friction-reducing effects of the Ni50 / hBN layer can be more stably exerted, further enhancing the overall wear resistance and crack / sparging resistance under dynamic loads and thermal cycling conditions.

[0016] Optionally, the high-entropy alloy powder is obtained by mixing 20.5-22.5 parts by weight of aluminum powder, 15.5-17.5 parts by weight of titanium powder, 13.5-15.5 parts by weight of copper powder, 24.0-26.0 parts by weight of manganese powder, and 22.5-24.5 parts by weight of chromium powder, adding 1.5-2.5 parts by weight of cyclohexane under argon protection, ball milling for 40-45 hours at a ball-to-powder ratio of 8:1-12:1 and a rotation speed of 280-320 rpm, and drying under vacuum at 60-80℃ for 6-10 hours.

[0017] Adding a small amount of cyclohexane as a process control agent under argon protection can lubricate and isolate the powder surface, reducing cold welding and agglomeration, lessening the adhesion of aluminum powder to the grinding balls and tank walls, and reducing oxidation and impurity introduction, thereby improving mixing uniformity and powder yield. Simultaneously, it helps reduce frictional heat generation during ball milling, minimizing the risk of microstructure coarsening and component segregation caused by localized overheating. Prolonged ball milling causes repeated plastic deformation and fragmentation of the powders, promoting thorough mixing and pre-alloying of multiple elements at the microscale, resulting in finer-grained powders with higher defect density and stronger activity, laying the foundation for subsequent sintering densification and microstructure homogenization.

[0018] Optionally, in step S1, 85-90 parts by mass of high-entropy alloy powder, 10-15 parts by mass of aluminum powder, 0.12-0.2 parts by mass of Sn powder, and 0.5-2 parts by mass of magnesium powder are mixed and stirred at 160-200 rpm for 6-12 hours, and then loaded into a graphite mold. The mixture is then subjected to discharge plasma sintering under an argon atmosphere. Under a pressure of 30-50 MPa, the temperature is first raised to 480°C at 50°C / min, then further raised to 520-550°C at 20°C / min and held for 8-12 minutes. The mixture is then transferred to a vacuum diffusion furnace, heated to 490-520°C, held for 10-20 minutes, and cooled to room temperature. The mixture is then crushed and sieved into 3-8 mm particles, and preheated at 280-320°C for 20-40 minutes to obtain the composite material.

[0019] The present invention crushes and sieves the final product into particles of 3-8 mm in size, making it easier for them to be uniformly fused with other melts under stirring conditions. This is beneficial for the stable introduction and uniform dispersion of high-entropy alloy powder, and avoids the problem that particles that are too small are easily carried away by the slag or float and agglomerate on the surface of the melt.

[0020] Optionally, in step S2, 70-80 parts by weight of aluminum ingots are added to a graphite crucible, followed by 4.0-4.6 parts by weight of zinc ingots, 4.6-5.4 parts by weight of magnesium ingots, and 0.10-0.20 parts by weight of metallic calcium particles. The mixture is heated to 740-770°C to melt and held at that temperature for 10-20 minutes. Then, 0.10-0.25 parts by weight of Al-5Ti-1B master alloy are added and stirred for 3-6 minutes, followed by 1.0-1.5 parts by weight of... The refining agent is stirred for 10-15 minutes to complete the refining and degassing. The slag is removed, and the melt temperature is adjusted to 730-740℃. The melt is mechanically stirred at 400-800 rpm for 10-20 minutes. At the same time, 8-15 parts by weight of composite material are added and stirred for 5-8 minutes. After standing for 2-3 minutes, high-purity argon gas is introduced for 2-5 minutes for secondary degassing. The melt is then cast and solidified at 730-740℃. After cleaning and polishing, a multi-element aluminum alloy shell is obtained.

[0021] Optionally, the multi-element aluminum alloy shell comprises the following raw materials in parts by weight: 70-80 parts aluminum ingot, 4.0-4.6 parts zinc ingot, 4.6-5.4 parts magnesium ingot, 0.10-0.20 parts metallic calcium particles, 0.10-0.25 parts Al-5Ti-1B master alloy, 1.0-1.5 parts refining agent, and 8-15 parts composite material.

[0022] By alloying aluminum ingots with zinc, magnesium, and trace amounts of calcium after melting, and purifying the melt with a refining agent before adding the composite material, the hydrogen content of the melt can be effectively reduced and oxide inclusions removed, improving melt cleanliness and casting stability. Adding an aluminum-titanium-boron master alloy significantly refines the as-cast grains, suppresses segregation and hot cracking tendencies, and enhances shell strength and toughness. Subsequently, the composite material is added under controlled temperature and speed with continued stirring, which facilitates rapid wetting and uniform dispersion of the composite material in the melt, reducing floating agglomeration. A second argon degassing process after stirring removes gases and fine inclusions reintroduced during addition and stirring, reducing pinholes, porosity, and slag inclusions, resulting in a denser as-cast structure and more consistent properties, thus obtaining a multi-element aluminum alloy shell that combines strength and service stability.

[0023] Optionally, the modified protective agent is obtained by mixing 56-59 parts by weight of high borosilicate glass powder, 40-42 parts by weight of anhydrous sodium tetraborate and 1.0-2.0 parts by weight of Y3NbO7 micro powder, ball milling at 200-300 rpm for 30-60 min, and drying at 200-260℃ for 1-2 h.

[0024] Preferably, the Y3NbO7 micro powder is prepared by mixing 32 parts by mass of methanol and 2.7 parts by mass of niobium pentachloride and stirring for 20 min, adding 57.6 parts by mass of citric acid and stirring continuously until the citric acid is completely dissolved, adding 5.37 parts by mass of yttrium carbonate and stirring magnetically for 1 h, adding 24.8 parts by mass of ethylene glycol and stirring for 10 min, heating to 130°C and continuing to heat and react for 3 h, cooling, placing in a box furnace, carbonizing at 300°C for 2 h, grinding into powder, heat-treating at 650°C for 2 h, grinding and passing through a 500-mesh sieve.

[0025] Optionally, in step S3, after cleaning and drying the inner cavity of the multi-element aluminum alloy shell, 1.0~1.5 kg / m² of [agent / material] is added according to the inner surface area of ​​the shell. 2Modified protective agent is applied. The shell is clamped on a centrifuge and rotated at 600 r / min for 1.0 to 1.5 min to allow the modified protective agent to spread and form a continuous coating layer on the inner surface. Then, the centrifuge speed is increased to 1150 to 1200 r / min, and molten gray cast iron is poured into the inner cavity of the multi-element aluminum alloy shell at 1330 to 1350°C, which is in a high-speed rotating state, so that a gray cast iron base is formed on the inner surface. The outer multi-element aluminum alloy shell is cooled by spraying water mist to control the shell temperature at 470 to 540°C and maintain it for 8 to 10 min. Then, water cooling is continued to control the shell temperature at 50 to 120°C, and solidification is performed to obtain the composite brake drum blank.

[0026] This invention pre-spreads a modified protective agent composed of high borosilicate glass powder, anhydrous sodium tetraborate, and a small amount of Y3NbO7 micro powder at the interface between the multi-element aluminum alloy shell and the gray cast iron before centrifugally casting the inner layer of gray cast iron. The anhydrous sodium tetraborate has a low softening temperature and good fluxing and film-removing effect, allowing the modified protective agent to soften or melt rapidly when the high-temperature gray cast iron reaches the interface, and to flux and remove the oxide film on the aluminum alloy surface, thereby improving interface cleanliness and effective contact. The high borosilicate glass powder, after melting, forms a glassy protective layer with moderate viscosity and good coverage. This protective layer can spread stably and continuously under centrifugal force, and provides a certain degree of thermal insulation, buffering, and erosion resistance, thus helping to reduce the transient thermal shock and localized ablation of the aluminum alloy shell by the high-temperature gray cast iron. Meanwhile, the formed glassy protective layer can also provide a certain barrier and buffer between Fe and Al, reducing the degree of direct contact between them. This helps to suppress the rapid and continuous formation of brittle Fe-Al intermetallic compounds at the interface, reducing the risk of interface delamination and crack initiation during subsequent cooling and thermal cycling. Furthermore, adding a small amount of Y3NbO7 micro powder as a high-temperature stable low thermal conductivity filler can improve the thermal resistance and high-temperature structural stability of the glassy protective layer, and enhance the thermal insulation and buffering effect of the interface without significantly affecting its spreadability. This is beneficial to improving the forming consistency and thermal cycling stability of the centrifugal composite interface, and reducing the probability of delamination, inclusions, and interface cracking.

[0027] Preferably, the thickness of the gray cast iron substrate is 3~10mm.

[0028] Optionally, in step S4, before preheating the composite brake drum blank, the composite brake drum blank is pretreated. The pretreatment steps are as follows: reheat the composite brake drum blank to 150~160℃ and keep it at that temperature for 3~5 hours, cool it to room temperature, sandblast the inner gray cast iron substrate, use Al2O3 as the sandblasting medium, and use a sandblasting pressure of 0.5~0.7MPa. After sandblasting, rinse with anhydrous ethanol for 5~10 minutes and dry at 100~120℃ for 30~60 minutes.

[0029] Optionally, in step S4, after preheating the pretreated composite brake drum blank to 300°C and holding it for 15-30 minutes, under the condition of high-purity argon gas with a flow rate of 10-15 L / min, Ni625 powder is first used to laser clad on a gray cast iron substrate to form a Ni625 layer, and then Ni50 / hBN composite powder is used to laser clad on the surface of the Ni625 layer to form a Ni50 / hBN layer. The blank is then held at 280-320°C for 5-10 minutes and cooled to room temperature to obtain a wear-resistant brake drum.

[0030] Preferably, the specific parameters for laser cladding to form the Ni625 layer are: laser power 1200~1400W, scanning speed 10mm / s, Ni625 powder feed rate 8~12g / min, laser spot diameter 2.8~3.2mm, and overlap rate 25%~35%; the specific parameters for laser cladding to form the Ni50 / hBN layer are: laser power 1100~1400W, scanning speed 10mm / s, laser spot diameter 1.8~2.2mm, overlap rate 30%~40%, and Ni50 / hBN composite powder feed rate 8~12g / min.

[0031] Preferably, the Ni625 layer has a thickness of 0.20~0.60mm, and the Ni50 / hBN layer has a thickness of 0.30~0.80mm.

[0032] Optionally, the Ni50 / hBN composite powder is prepared by premixing 95-97 parts by weight of Ni50 powder and 3-5 parts by weight of hBN powder.

[0033] The above-described technical solution of the present invention has at least the following beneficial effects:

[0034] 1. This invention prioritizes the spark plasma sintering of high-entropy alloy powder and aluminum powder to form an aluminum-based coating on the surface of the high-entropy alloy particles, creating a core-shell composite material with high-entropy alloy particles as the core and an aluminum-based coating layer as the shell. The aluminum-based coating on the outer layer of the core and shell particles is homologous and in the same phase as the molten aluminum. After melting, the shell layer can preferentially fuse to form a continuous transition interface, preventing the high-entropy alloy core from directly contacting the melt with exposed particles, reducing repulsion, floating, and agglomeration caused by the oxide film and interfacial tension difference. The shell layer also acts as an isolation and pre-dispersion layer, reducing defects such as inclusions and gas entrapment, weakening interface abrupt changes and component enrichment, inhibiting violent reactions and the formation of coarse and brittle intermetallic compounds, and improving the as-cast density and bonding strength. The diffusion transition zone achieves stress relief and plastic coordination, improves load transfer, inhibits debonding and microcracks, enhances fatigue and impact resistance, and also takes into account toughness.

[0035] 2. Ni625 is first clad onto the surface of gray cast iron as a transition layer, so that the matrix is ​​melted and diluted mainly within this layer. This reduces the disturbance of Fe and C on the composition and structure of the upper Ni50 / hBN layer, and reduces embrittlement, crack sensitivity, and formation of pore / microcrack channels caused by compositional deviation and abrupt changes in structure. This reduces the risk of oxidizing medium penetration and repeated oxide film rupture, and improves high-temperature oxidation stability and thermal fatigue life. At the same time, Ni625 has good toughness and high-temperature stability, which can alleviate thermophysical property mismatch and reduce residual tensile stress, enhance interlayer metallurgical bonding, reduce hot cracking and spalling, and provide a reliable load-bearing foundation for the upper layer.

[0036] 3. Based on the stable load-bearing structure of Ni625, the Ni50 / hBN layer uses Ni50 nickel-based alloy as its framework. Its high hardness and reinforcing phases enhance its resistance to abrasive wear and plastic deformation. hBN, as a layered solid lubricating phase, easily slips during friction and forms a transfer film, reducing the coefficient of friction and adhesive wear, minimizing frictional heat accumulation, and thus inhibiting microcrack propagation and spalling. Ni625 reduces dilution and enhances bonding strength, making the load-bearing and friction-reducing effects of Ni50 / hBN more stable, further improving its wear resistance, crack resistance, and spalling resistance under dynamic loads and thermal cycling. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0038] The gray cast iron used in this embodiment of the invention is HT250 gray cast iron, purchased from Wuxi Qiujing New Materials Group. Its main chemical composition is: carbon 2.9%~3.6%, silicon 1.2%~2.0%, manganese 0.6%~1.2%, phosphorus ≤0.15%, sulfur ≤0.12%, and the remainder is iron; the Al-5Ti-1B master alloy was purchased from Jiangsu Qingchuang New Materials Co., Ltd.; the refining agent was purchased from Anhui Pairui High Temperature Materials Co., Ltd.; the Ni625 alloy powder was purchased from Zhuoyue Alloy Powder, with a particle size of 53~120μm, and its main chemical composition (mass fraction) is: Cr 20.0%~23.0%, Mo 8.0%~10.0%, Nb 3.15%~4.15%, Fe ≤5.0%, Si ≤0.50%, and the remainder is Ni; the Ni50 alloy powder was purchased from Nangong Haitai Alloy Welding Materials Factory, with a particle size of 40~80μm, and its main chemical composition is: Cr 12.0%~16.0%, Si 3.0%~4.5%, C 0.4%~0.8%, Fe≤5.0%, the remainder is Ni; the hexagonal boron nitride (hBN) powder was purchased from Xinyang Defupeng New Materials, with a particle size of 1~5μm and a purity ≥99.5%.

[0039] Preparation: By weight, 32 parts methanol and 2.7 parts niobium pentachloride were mixed and stirred for 20 min. 57.6 parts citric acid were added and stirred until the citric acid was completely dissolved. 5.37 parts yttrium carbonate were added and stirred magnetically for 1 h. 24.8 parts ethylene glycol were added and stirred for 10 min. The mixture was heated to 130°C and reacted continuously for 3 h. After cooling, the mixture was placed in a box furnace and carbonized at 300°C for 2 h. It was then ground into powder and heat-treated at 650°C for 2 h. The powder was then ground and passed through a 500-mesh sieve to obtain Y3NbO7 micro powder.

[0040] Example 1

[0041] By weight, 20.5 parts aluminum powder, 15.5 parts titanium powder, 13.5 parts copper powder, 24.0 parts manganese powder, and 22.5 parts chromium powder were mixed, and 1.5 parts cyclohexane were added under argon protection. The mixture was ball-milled for 40 hours at a ball-to-powder ratio of 8:1 and a rotation speed of 280 rpm. After drying under vacuum at 60℃ for 6 hours, high-entropy alloy powder was obtained. 85 parts high-entropy alloy powder, 10 parts aluminum powder, 0.12 parts Sn powder, and 0.5 parts magnesium powder were mixed and stirred at 160 rpm for 6 hours and then loaded into a graphite mold. Spark plasma sintering was performed under an argon atmosphere. The temperature was first raised to 480℃ at 50℃ / min under a pressure of 30 MPa, and then raised to 520℃ at 20℃ / min and held for 8 minutes. The mixture was then transferred to a vacuum diffusion furnace, heated to 490℃ and held for 10 minutes, and cooled to room temperature. The mixture was crushed and sieved into 3 mm particles and preheated at 280℃ for 20 minutes to obtain the composite material.

[0042] By weight, 70 parts of aluminum ingot were added to a graphite crucible, followed by 4.0 parts of zinc ingot, 4.6 parts of magnesium ingot, and 0.10 parts of metallic calcium granules. The mixture was heated to 740℃ to melt and held for 10 minutes. 0.10 parts of Al-5Ti-1B master alloy were added and stirred for 3 minutes. Then, 1.0 part of refining agent was added and stirred for another 10 minutes to complete the refining and degassing. The slag was removed, and the melt temperature was adjusted to 730℃ and mechanically stirred at 400 rpm for 10 minutes. At the same time, 8 parts of composite material were added and stirred for another 5 minutes. After standing for 2 minutes, high-purity argon gas was introduced for 2 minutes for secondary degassing. The melt was then cast and solidified at 730℃. After cleaning and polishing, a multi-element aluminum alloy shell was obtained.

[0043] By weight, 56 parts of high borosilicate glass powder (325 mesh), 40 parts of anhydrous sodium tetraborate, and 1.0 part of Y3NbO7 micro powder were mixed and ball-milled at 200 rpm for 30 min, and then dried at 200℃ for 1 h to obtain a modified protective agent. After cleaning and drying the inner cavity of the multi-element aluminum alloy shell, 1.1 kg / m² of the modified protective agent was added according to the inner surface area of ​​the shell. 2 Modified protective agent: The shell is clamped on a centrifuge and rotated at 600 r / min for 1.0 min to allow the modified protective agent to spread and form a continuous coating layer on the inner surface. Then, the centrifuge speed is increased to 1150 r / min, and gray cast iron molten iron is poured into the inner cavity of the multi-element aluminum alloy shell at 1330℃, so that a gray cast iron base with a thickness of 3 mm is formed on the inner surface. The outer multi-element aluminum alloy shell is cooled by spraying water mist to control the shell temperature at 470℃ and maintain it for 8 min. Then, water cooling is continued to control the shell temperature at 50℃ and solidify to obtain the composite brake drum blank.

[0044] The composite brake drum blank was reheated to 150℃ and held for 3 hours, then cooled to room temperature. The inner gray cast iron base was sandblasted with Al2O3 as the sandblasting medium and 0.5MPa as the sandblasting pressure. After sandblasting, it was rinsed with anhydrous ethanol for 5 minutes and dried at 100℃ for 30 minutes to obtain the pretreated composite brake drum blank.

[0045] By weight, 97 parts of Ni50 powder and 4 parts of hBN powder were premixed to obtain Ni50 / hBN composite powder. The pretreated composite brake drum blank was preheated to 300℃ and held for 15 min. Then, under high-purity argon gas at a flow rate of 10 L / min, Ni625 powder was first used to laser cladize a gray cast iron substrate to form a Ni625 layer. The laser power was set to 1200 W, the scanning speed to 10 mm / s, the powder feed rate to 8 g / min, and the laser spot diameter to 2.8 μm. The Ni625 layer has a thickness of 0.20 mm and an overlap rate of 25%. Then, Ni50 / hBN composite powder is used to laser-clad the Ni625 layer to form a Ni50 / hBN layer. The laser power is set to 1100 W, the scanning speed to 10 mm / s, the laser spot diameter to 1.8 mm, the overlap rate to 30%, and the powder feed rate to 8 g / min. After the Ni50 / hBN layer thickness is 0.30 mm, the mixture is held at 280℃ for 5 min and then cooled to room temperature to obtain a wear-resistant brake drum.

[0046] Example 2

[0047] By weight, 22.5 parts aluminum powder, 17.5 parts titanium powder, 15.5 parts copper powder, 26.0 parts manganese powder, and 24.5 parts chromium powder were mixed, and 2.5 parts cyclohexane were added under argon protection. The mixture was ball-milled for 45 hours at a ball-to-powder ratio of 12:1 and a rotation speed of 320 rpm. After drying under vacuum at 80℃ for 10 hours, high-entropy alloy powder was obtained. 90 parts high-entropy alloy powder, 15 parts aluminum powder, 0.20 parts Sn powder, and 2.0 parts magnesium powder were mixed and stirred at 200 rpm for 12 hours and then loaded into a graphite mold. Spark plasma sintering was performed under an argon atmosphere. The temperature was first raised to 480℃ at 50℃ / min under a pressure of 50 MPa, and then raised to 550℃ at 20℃ / min and held for 12 minutes. The mixture was then transferred to a vacuum diffusion furnace, heated to 520℃ and held for 20 minutes, and cooled to room temperature. The mixture was crushed and sieved into 8 mm particles and preheated at 320℃ for 40 minutes to obtain the composite material.

[0048] By weight, 80 parts of aluminum ingot were added to a graphite crucible, followed by 4.6 parts of zinc ingot, 5.4 parts of magnesium ingot, and 0.20 parts of metallic calcium granules. The mixture was heated to 770℃ to melt and held for 20 minutes. 0.25 parts of Al-5Ti-1B master alloy were added and stirred for 6 minutes. Then, 1.5 parts of refining agent were added and stirring was continued for 15 minutes to complete refining and degassing. The slag was removed, and the melt temperature was adjusted to 740℃ and mechanically stirred at 800 rpm for 20 minutes. At the same time, 15 parts of composite material were added and stirring was continued for 8 minutes. After standing for 3 minutes, high-purity argon gas was introduced for 5 minutes for secondary degassing. The melt was then cast and solidified at 740℃. After cleaning and polishing, a multi-element aluminum alloy shell was obtained.

[0049] By weight, 59 parts of high borosilicate glass powder (325 mesh), 42 parts of anhydrous sodium tetraborate, and 2.0 parts of Y3NbO7 micro powder were mixed and ball-milled at 300 rpm for 60 min. The mixture was then dried at 260℃ for 2 h to obtain a modified protective agent. After cleaning and drying the inner cavity of the multi-element aluminum alloy shell, 1.2 kg / m² of the modified protective agent was added based on the inner surface area of ​​the shell. 2 Modified protective agent: The shell is clamped on a centrifuge and rotated at 600 r / min for 1.5 min to allow the modified protective agent to spread and form a continuous coating layer on the inner surface. Then, the centrifuge speed is increased to 1200 r / min, and molten gray cast iron is poured into the inner cavity of the multi-element aluminum alloy shell at 1350℃, so that a gray cast iron base with a thickness of 10 mm is formed on the inner surface. The outer multi-element aluminum alloy shell is cooled by spraying water mist to control the shell temperature at 540℃ and maintain it for 10 min. Then, water cooling is continued to control the shell temperature at 120℃ and solidify to obtain the composite brake drum blank.

[0050] The composite brake drum blank was reheated to 160℃ and held for 5 hours, then cooled to room temperature. The inner gray cast iron base was sandblasted with Al2O3 as the sandblasting medium and 0.7MPa as the sandblasting pressure. After sandblasting, it was rinsed with anhydrous ethanol for 10 minutes and dried at 120℃ for 60 minutes to obtain the pretreated composite brake drum blank.

[0051] By weight, 95 parts of Ni50 powder and 5 parts of hBN powder were premixed to obtain Ni50 / hBN composite powder. The pretreated composite brake drum blank was preheated to 300℃ and held for 30 min. Laser cladding was then performed under high-purity argon gas with a flow rate of 15 L / min. First, Ni625 powder was used to laser clad onto a gray cast iron substrate to form a Ni625 layer. The laser power was set to 1400 W, the scanning speed to 10 mm / s, the powder feed rate to 12 g / min, and the laser spot diameter to 3 mm / min. The Ni625 layer is 0.60 mm thick with an overlap rate of 35%. Then, Ni50 / hBN composite powder is used to laser clad the surface of the Ni625 layer to form a Ni50 / hBN layer. The laser power is set to 1400 W, the scanning speed is 10 mm / s, the laser spot diameter is 2.2 mm, the overlap rate is 40%, the powder feed rate is 12 g / min, and the Ni50 / hBN layer thickness is 0.80 mm. After holding at 320℃ for 10 min, it is cooled to room temperature to obtain a wear-resistant brake drum.

[0052] Example 3

[0053] By weight, 21.8 parts aluminum powder, 16.8 parts titanium powder, 14.2 parts copper powder, 25.2 parts manganese powder, and 23.8 parts chromium powder were mixed, and 2.1 parts cyclohexane were added under argon protection. The mixture was ball-milled for 42 hours at a ball-to-powder ratio of 10:1 and a rotation speed of 305 rpm. After drying under vacuum at 72℃ for 8 hours, high-entropy alloy powder was obtained. 87 parts high-entropy alloy powder, 13 parts aluminum powder, 0.16 parts Sn powder, and 1.2 parts magnesium powder were mixed and stirred at 180 rpm for 9 hours and then loaded into a graphite mold. Spark plasma sintering was performed under an argon atmosphere. The temperature was first raised to 480℃ at 50℃ / min under a pressure of 42 MPa, and then raised to 538℃ at 20℃ / min and held for 10 minutes. The mixture was then transferred to a vacuum diffusion furnace, heated to 508℃ and held for 16 minutes, and cooled to room temperature. The mixture was crushed and sieved into 5 mm particles and preheated at 305℃ for 30 minutes to obtain the composite material.

[0054] By weight, 75 parts of aluminum ingot were added to a graphite crucible, followed by 4.3 parts of zinc ingot, 5.0 parts of magnesium ingot, and 0.15 parts of metallic calcium granules. The mixture was heated to 755℃ to melt and held for 15 minutes. 0.18 parts of Al-5Ti-1B master alloy were added and stirred for 4 minutes. Then, 1.2 parts of refining agent were added and stirring was continued for 12 minutes to complete refining and degassing. The slag was removed, and the melt temperature was adjusted to 735℃ and mechanically stirred at 550 rpm for 15 minutes. At the same time, 12 parts of composite material were added and stirring was continued for 6 minutes. After standing for 2.5 minutes, high-purity argon gas was introduced for 3 minutes for secondary degassing. The melt was then cast and solidified at 735℃. After cleaning and polishing, a multi-element aluminum alloy shell was obtained.

[0055] By weight, 58 parts of high borosilicate glass powder (325 mesh), 41 parts of anhydrous sodium tetraborate, and 1.5 parts of Y3NbO7 micro powder were mixed and ball-milled at 250 rpm for 45 min. The mixture was then dried at 230℃ for 1.5 h to obtain a modified protective agent. After cleaning and drying the inner cavity of the multi-element aluminum alloy shell, 1.15 kg / m² of the modified protective agent was added based on the inner surface area of ​​the shell. 2 Modified protective agent: The shell is clamped on a centrifuge and rotated at 600 r / min for 1.2 min to allow the modified protective agent to spread and form a continuous coating layer on the inner surface. Then, the centrifuge speed is increased to 1180 r / min, and gray cast iron molten iron is poured into the inner cavity of the multi-element aluminum alloy shell at 1340℃, which is in a high-speed rotating state, so that a gray cast iron base is formed on the inner surface. The thickness of the gray cast iron base is 6 mm. The outer multi-element aluminum alloy shell is cooled by spraying water mist to control the shell temperature at 500℃ and maintain it for 9 min. Then, water cooling is continued to control the shell temperature at 80℃ and solidify to obtain the composite brake drum blank.

[0056] The composite brake drum blank was reheated to 155℃ and held for 4 hours, then cooled to room temperature. The inner gray cast iron base was sandblasted with Al2O3 as the sandblasting medium and 0.6MPa as the sandblasting pressure. After sandblasting, it was rinsed with anhydrous ethanol for 7 minutes and dried at 110℃ for 45 minutes to obtain the pretreated composite brake drum blank.

[0057] By weight, 95.2 parts of Ni50 powder and 3.0 parts of hBN powder were premixed to obtain Ni50 / hBN composite powder. The pretreated composite brake drum blank was preheated to 300℃ and held for 20 min, then laser cladding was performed under high-purity argon gas at a flow rate of 12 L / min. First, Ni625 powder was used to laser cladize a gray cast iron substrate to form a Ni625 layer. The laser power was set to 1300 W, the scanning speed to 10 mm / s, the powder feed rate to 10 g / min, and the laser spot diameter to be... With a diameter of 3.0 mm, an overlap rate of 30%, and a Ni625 layer thickness of 0.40 mm, Ni50 / hBN composite powder is then laser-clad onto the surface of the Ni625 layer to form a Ni50 / hBN layer. The laser power is set to 1250 W, the scanning speed to 10 mm / s, the laser spot diameter to 2.0 mm, the overlap rate to 35%, the powder feed rate to 10 g / min, and the Ni50 / hBN layer thickness to 0.50 mm. After holding at 300 °C for 7 min and cooling to room temperature, a wear-resistant brake drum is obtained.

[0058] Example 4

[0059] By weight, 21.0 parts aluminum powder, 16.0 parts titanium powder, 14.0 parts copper powder, 24.5 parts manganese powder, and 23.0 parts chromium powder were mixed, and 1.8 parts cyclohexane were added under argon protection. The mixture was ball-milled for 41 hours at a ball-to-powder ratio of 9:1 and a rotation speed of 290 rpm. After drying under vacuum at 65℃ for 7 hours, high-entropy alloy powder was obtained. 86 parts high-entropy alloy powder, 14 parts aluminum powder, 0.15 parts Sn powder, and 1.0 parts magnesium powder were mixed and stirred at 170 rpm for 7 hours and then loaded into a graphite mold. Spark plasma sintering was performed under an argon atmosphere. The temperature was first raised to 480℃ at 50℃ / min under a pressure of 35 MPa, and then raised to 525℃ at 20℃ / min and held for 9 minutes. The mixture was then transferred to a vacuum diffusion furnace, heated to 495℃ and held for 12 minutes, and cooled to room temperature. The mixture was crushed and sieved into 4 mm particles and preheated at 290℃ for 25 minutes to obtain the composite material.

[0060] By weight, 72 parts of aluminum ingot were added to a graphite crucible, followed by 4.1 parts of zinc ingot, 4.8 parts of magnesium ingot, and 0.12 parts of metallic calcium granules. The mixture was heated to 745℃ to melt and held for 12 minutes. 0.12 parts of Al-5Ti-1B master alloy were added and stirred for 3 minutes. Then, 1.0 part of refining agent was added and stirring was continued for 10 minutes to complete refining and degassing. The slag was removed, and the melt temperature was adjusted to 730℃ and mechanically stirred at 450 rpm for 12 minutes. At the same time, 9 parts of composite material were added and stirring was continued for 5 minutes. After standing for 2 minutes, high-purity argon gas was introduced for 2 minutes for secondary degassing. The melt was then cast and solidified at 730℃. After cleaning and polishing, a multi-element aluminum alloy shell was obtained.

[0061] By weight, 57 parts of high borosilicate glass powder (325 mesh), 41.5 parts of anhydrous sodium tetraborate, and 1.5 parts of Y3NbO7 micro powder were mixed and ball-milled at 230 rpm for 40 min. The mixture was then dried at 220℃ for 1.2 h to obtain a modified protective agent. After cleaning and drying the inner cavity of the multi-element aluminum alloy shell, 1.12 kg / m² of the modified protective agent was added based on the inner surface area of ​​the shell. 2 Modified protective agent: The shell is clamped on a centrifuge and rotated at 600 r / min for 1.1 min to spread the modified protective agent on the inner surface to form a continuous coating layer. Then, the centrifuge speed is increased to 1160 r / min, and molten gray cast iron is poured into the inner cavity of the multi-element aluminum alloy shell at 1335℃, forming a gray cast iron base with a thickness of 4 mm on the inner surface. The outer multi-element aluminum alloy shell is cooled by spraying water mist to control the shell temperature at 480℃ and maintain it for 8 min. Then, water mist cooling is continued to control the shell temperature at 70℃ and solidification is performed to obtain a composite brake drum blank. The composite brake drum blank is reheated to 152℃ and held for 3.5 h, cooled to room temperature, and the inner gray cast iron base is sandblasted with Al2O3 as the sandblasting medium at a sandblasting pressure of 0.55 MPa. After sandblasting, it is rinsed with anhydrous ethanol for 6 min and dried at 105℃ for 40 min to obtain a pretreated composite brake drum blank.

[0062] By weight, 97 parts of Ni50 powder and 3 parts of hBN powder were premixed to obtain Ni50 / hBN composite powder. The pretreated composite brake drum blank was preheated to 300℃ and held for 18 min, and then laser cladding was performed under high-purity argon gas at a flow rate of 11 L / min. First, Ni625 powder was used to laser clad onto a gray cast iron substrate to form a Ni625 layer. The laser power was set to 1250W, the scanning speed to 10 mm / s, the powder feed rate to 9 g / min, and the laser spot diameter to 2 mm / s. The Ni625 layer is 0.30 mm thick with an overlap rate of 28%. Then, Ni50 / hBN composite powder is used to laser clad the Ni625 layer to form a Ni50 / hBN layer on the surface of the Ni625 layer. The laser power is set to 1150W, the scanning speed is 10 mm / s, the laser spot diameter is 1.9 mm, the overlap rate is 32%, the powder feed rate is 9 g / min, and the Ni50 / hBN layer thickness is 0.40 mm. After holding at 290℃ for 6 min, it is cooled to room temperature to obtain a wear-resistant brake drum.

[0063] Example 5

[0064] By weight, 22.0 parts aluminum powder, 17.0 parts titanium powder, 15.0 parts copper powder, 25.5 parts manganese powder, and 24.0 parts chromium powder were mixed, and 2.3 parts cyclohexane were added under argon protection. The mixture was ball-milled for 44 hours at a ball-to-powder ratio of 11:1 and a rotation speed of 310 rpm. After drying under vacuum at 75℃ for 9 hours, high-entropy alloy powder was obtained. 88 parts high-entropy alloy powder, 12 parts aluminum powder, 0.18 parts Sn powder, and 1.6 parts magnesium powder were mixed and stirred at 190 rpm for 10 hours and then loaded into a graphite mold. Spark plasma sintering was performed under an argon atmosphere. The temperature was first raised to 480℃ at 50℃ / min under a pressure of 45 MPa, and then raised to 545℃ at 20℃ / min and held for 11 minutes. The mixture was then transferred to a vacuum diffusion furnace, heated to 515℃ and held for 18 minutes, and cooled to room temperature. The mixture was crushed and sieved into 6 mm particles and preheated at 310℃ for 35 minutes to obtain the composite material.

[0065] By weight, 78 parts of aluminum ingots were added to a graphite crucible, followed by 4.5 parts of zinc ingots, 5.3 parts of magnesium ingots, and 0.18 parts of metallic calcium granules. The mixture was heated to 765℃ to melt and held for 18 minutes. 0.22 parts of Al-5Ti-1B master alloy were added and stirred for 5 minutes. Then, 1.4 parts of refining agent were added and stirring was continued for 14 minutes to complete refining and degassing. The slag was removed, and the melt temperature was adjusted to 740℃ and mechanically stirred at 700 rpm for 18 minutes. At the same time, 15 parts of composite material were added and stirring was continued for 8 minutes. After standing for 3 minutes, high-purity argon gas was introduced for 4 minutes for secondary degassing. The melt was then cast and solidified at 740℃. After cleaning and polishing, a multi-element aluminum alloy shell was obtained.

[0066] By weight, 58.5 parts of high borosilicate glass powder (325 mesh), 40.0 parts of anhydrous sodium tetraborate, and 1.5 parts of Y3NbO7 micro powder were mixed and ball-milled at 280 rpm for 55 min. The mixture was then dried at 245℃ for 1.8 h to obtain the modified protective agent. After cleaning and drying the inner cavity of the multi-element aluminum alloy shell, 1.18 kg / m² of the modified protective agent was added based on the inner surface area of ​​the shell. 2 The modified protective agent was applied, and the shell was clamped onto a centrifuge. The centrifuge was rotated at 600 rpm for 1.4 minutes to allow the modified protective agent to spread and form a continuous coating layer on the inner surface. The centrifuge speed was then increased to 1190 rpm, and molten gray cast iron was poured into the inner cavity of the high-speed rotating multi-element aluminum alloy shell at 1348℃, forming a gray cast iron base with a thickness of 8 mm on the inner surface. The outer multi-element aluminum alloy shell was then cooled by spraying water mist. The temperature was controlled at 520℃ and held for 10 minutes, then water was sprayed to cool the shell to 110℃, and solidification was carried out to obtain a composite brake drum blank. The composite brake drum blank was reheated to 158℃ and held for 4.5 hours, then cooled to room temperature. The inner gray cast iron base was sandblasted with Al2O3 as the sandblasting medium and 0.65 MPa as the sandblasting pressure. After sandblasting, it was rinsed with anhydrous ethanol for 9 minutes and dried at 118℃ for 55 minutes to obtain the pretreated composite brake drum blank.

[0067] By weight, 96.5 parts of Ni50 powder and 3.5 parts of hBN powder were premixed to obtain Ni50 / hBN composite powder. The pretreated composite brake drum blank was preheated to 300℃ and held for 25 min, and then laser cladding was performed under high-purity argon gas at a flow rate of 14 L / min. First, Ni625 powder was used to laser clad onto a gray cast iron substrate to form a Ni625 layer. The laser power was set to 1380W, the scanning speed to 10 mm / s, the powder feed rate to 11 g / min, and the laser spot diameter to be... With a diameter of 3.1 mm, an overlap rate of 33%, and a Ni625 layer thickness of 0.55 mm, Ni50 / hBN composite powder was then laser-clad onto the surface of the Ni625 layer to form a Ni50 / hBN layer. The laser power was set to 1350 W, the scanning speed to 10 mm / s, the laser spot diameter to 2.1 mm, the overlap rate to 38%, and the powder feed rate to 11 g / min. After the Ni50 / hBN layer thickness was 0.75 mm, the mixture was held at 315 °C for 9 min and then cooled to room temperature to obtain a wear-resistant brake drum.

[0068] Example 6

[0069] By weight, 21.5 parts aluminum powder, 16.5 parts titanium powder, 14.5 parts copper powder, 25.0 parts manganese powder, and 23.5 parts chromium powder were mixed, and 2.0 parts cyclohexane were added under argon protection. The mixture was ball-milled for 43 hours at a ball-to-powder ratio of 10:1 and a rotation speed of 300 rpm. After drying under vacuum at 70℃ for 8 hours, high-entropy alloy powder was obtained. 89 parts high-entropy alloy powder, 11 parts aluminum powder, 0.14 parts Sn powder, and 0.8 parts magnesium powder were mixed and stirred at 175 rpm for 8 hours and then loaded into a graphite mold. Spark plasma sintering was performed under an argon atmosphere. The temperature was first raised to 480℃ at 50℃ / min under a pressure of 40 MPa, and then raised to 535℃ at 20℃ / min and held for 10 minutes. The mixture was then transferred to a vacuum diffusion furnace, heated to 505℃ and held for 15 minutes, and cooled to room temperature. The mixture was crushed and sieved into 5 mm particles and preheated at 300℃ for 30 minutes to obtain the composite material.

[0070] By weight, 76 parts of aluminum ingot were added to a graphite crucible, followed by 4.2 parts of zinc ingot, 5.1 parts of magnesium ingot, and 0.14 parts of metallic calcium granules. The mixture was heated to 758℃ to melt and held for 16 minutes. 0.16 parts of Al-5Ti-1B master alloy were added and stirred for 4 minutes. Then, 1.2 parts of refining agent were added and stirring was continued for 12 minutes to complete refining and degassing. The slag was removed, and the melt temperature was adjusted to 735℃ and mechanically stirred at 520 rpm for 14 minutes. At the same time, 11 parts of composite material were added and stirring was continued for 6 minutes. After standing for 2.5 minutes, high-purity argon gas was introduced for 3 minutes for secondary degassing. The melt was then cast and solidified at 735℃. After cleaning and polishing, a multi-element aluminum alloy shell was obtained.

[0071] By weight, 57.5 parts of high borosilicate glass powder (325 mesh), 41.0 parts of anhydrous sodium tetraborate, and 1.5 parts of Y3NbO7 micro powder were mixed and ball-milled at 260 rpm for 50 min. The mixture was then dried at 235℃ for 1.5 h to obtain the modified protective agent. After cleaning and drying the inner cavity of the multi-element aluminum alloy shell, 1.15 kg / m² of the modified protective agent was added based on the inner surface area of ​​the shell. 2 Modified protective agent: The shell is clamped on a centrifuge and rotated at 600 r / min for 1.3 min to allow the modified protective agent to spread and form a continuous coating layer on the inner surface. Then, the centrifuge speed is increased to 1185 r / min, and gray cast iron molten iron is poured into the inner cavity of the multi-element aluminum alloy shell at 1342℃, so that a gray cast iron base with a thickness of 7 mm is formed on the inner surface. The outer multi-element aluminum alloy shell is cooled by spraying water mist to control the shell temperature at 505℃ and maintain it for 9 min. Then, water cooling is continued to control the shell temperature at 95℃ and solidify to obtain the composite brake drum blank.

[0072] The composite brake drum blank was reheated to 156℃ and held for 4 hours, then cooled to room temperature. The inner gray cast iron base was sandblasted with Al2O3 as the sandblasting medium and 0.60 MPa as the sandblasting pressure. After sandblasting, it was rinsed with anhydrous ethanol for 8 minutes and dried at 112℃ for 50 minutes to obtain the pretreated composite brake drum blank.

[0073] By weight, 96.2 parts of Ni50 powder and 3.8 parts of hBN powder were premixed to obtain Ni50 / hBN composite powder. The pretreated composite brake drum blank was preheated to 300℃ and held for 22 min, then laser cladding was performed under high-purity argon gas at a flow rate of 13 L / min. First, Ni625 powder was used to laser cladize a gray cast iron substrate to form a Ni625 layer. The laser power was set to 1320 W, the scanning speed to 10 mm / s, the powder feed rate to 10 g / min, and the laser spot diameter to be... With a diameter of 3.0 mm, an overlap rate of 30%, and a Ni625 layer thickness of 0.45 mm, Ni50 / hBN composite powder was then laser-clad onto the surface of the Ni625 layer to form a Ni50 / hBN layer. The laser power was set to 1280 W, the scanning speed to 10 mm / s, the laser spot diameter to 2.0 mm, the overlap rate to 35%, the powder feed rate to 10 g / min, and the Ni50 / hBN layer thickness to 0.60 mm. After holding at 305 °C for 8 min and cooling to room temperature, a wear-resistant brake drum was obtained.

[0074] The present invention also includes comparative examples and related experiments.

[0075] Comparative Example 1

[0076] Compared with Example 6, the only difference is that high-entropy alloy-aluminum core-shell particles were not prepared. Instead, aluminum powder, titanium powder, copper powder, manganese powder, and chromium powder were directly mixed in to prepare a multi-element aluminum alloy shell. The other preparation methods and compositions were completely consistent, and a wear-resistant brake drum was finally obtained.

[0077] Comparative Example 2

[0078] Compared with Example 6, the only difference is that the Ni625 layer and Ni50 / hBN layer were not laser clad, but the other preparation methods and compositions were completely consistent, and the wear-resistant brake drum was finally obtained.

[0079] Comparative Example 3

[0080] Compared with Example 6, the only difference is that the Ni625 layer was not laser clad, and the Ni50 / hBN layer was directly laser clad on the gray cast iron substrate. The other preparation methods and compositions are completely the same, and the wear-resistant brake drum is finally obtained.

[0081] Performance testing

[0082] To evaluate the mechanical strength performance of the wear-resistant brake drum of the present invention, mechanical property tests were conducted on the wear-resistant brake drum samples prepared in Examples 1-6 and Comparative Example 1. The tests were conducted in accordance with the national standard GB / T228.1-2021 "Metallic Materials - Tensile Testing" to evaluate the tensile strength, yield strength, and elongation of each sample. The specific test results are shown in Table 1.

[0083] Table 1

[0084]

[0085] As shown in Table 1, the tensile strength of the samples prepared in Examples 1-6 was 392-442 MPa, the yield strength was 273-304 MPa, and the elongation after fracture was 9.8%-12.4%, all exhibiting high load-bearing capacity and good deformation limit. The tensile strength and yield strength of Comparative Example 1 were 328 MPa and 219 MPa, respectively, and the elongation after fracture was 6.4%, which were generally lower than those of the examples. This indicates that under the same material system, the process of the present invention is more conducive to obtaining multi-element aluminum alloy shells with higher strength and better fracture resistance, thus demonstrating better strength and toughness.

[0086] In addition, the working surface hardness of the wear-resistant brake drum samples prepared in Examples 1-6 and Comparative Examples 2-3 was tested according to the national standard GB / T4340.1-2024 "Metallic Materials Vickers Hardness Test - Part 1 Test Method". The wear and friction performance was tested according to the national standard GB / T12444-2006 "Metallic Materials Wear Test Method - Test Ring-Block Sliding Wear Test". High-temperature oxidation test was conducted according to the national standard GB / T13303-1991 "Method for Determination of Oxidation Resistance of Steel" to evaluate oxidation resistance stability by oxidation weight gain per unit area. Finally, thermomechanical fatigue evaluation was conducted according to the national standard GB / T33812-2017 "Metallic Materials Fatigue Test - Strain Control Thermomechanical Fatigue Test Method". The thermal fatigue crack initiation life was examined by cyclic thermal shock method, and the number of cycles when visible crack initiation occurred was recorded. The specific test results are shown in Table 2.

[0087] Table 2

[0088]

[0089] As shown in Table 2, the working surface hardness of Examples 1-6 of the present invention is 566-632 HV, and the wear volume is 4.4-6.9 mm. 3 The average coefficient of friction is 0.35~0.38, and the oxidation weight gain is 0.78~1.02 mg / cm³. 2The number of thermal fatigue crack initiation cycles was 1320~1680, indicating that Examples 1~6 of the present invention have superior hardness, wear resistance, friction reduction, oxidation stability, and thermal fatigue life. Comparative Example 2, with unlaminated Ni625 and Ni50 / hBN layers, had a working surface hardness of only 230 HV and a wear volume increased to 18.5 mm. 3 The coefficient of friction is 0.45, and the oxidative weight gain reaches 2.10 mg / cm³. 2 Furthermore, the number of thermal fatigue crack initiation cycles was only 650, significantly inferior to the example. In Comparative Example 3, omitting the Ni625 buffer layer resulted in a decrease in working surface hardness to 485 HV and an increase in wear volume to 9.7 mm. 3 The coefficient of friction increased to 0.40, and the oxidative weight gain increased to 1.55 mg / cm³. 2 Furthermore, the number of thermal fatigue crack initiation cycles decreased to 980, indicating that setting a Ni625 buffer layer is beneficial to improving the overall stability of the cladding layer and making the friction reduction effect of the Ni50 / hBN layer more stable.

[0090] The above are preferred embodiments of the present invention. Those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A manufacturing process for a wear-resistant brake drum, characterized in that, Includes the following steps: S1. Mix and stir high-entropy alloy powder, aluminum powder, Sn powder and magnesium powder, perform discharge plasma sintering under argon atmosphere, pressurize, heat up, vacuum diffuse, cool, crush and sieve, and preheat to obtain composite material. S2. Add aluminum ingots to a graphite crucible, then add zinc ingots, magnesium ingots, and metallic calcium particles in sequence. Heat and melt the mixture, keep it warm, then add Al-5Ti-1B intermediate alloy in sequence and stir. Refine and degas, remove slag, add composite material and continue stirring, let stand, degas, cast into shape, clean and polish to obtain a multi-element aluminum alloy shell. S3. After cleaning and drying the inner cavity of the multi-element aluminum alloy shell, add a modified protective agent, rotate to spread the modified protective agent on the inner surface to form a continuous covering layer, increase the speed, pour in gray cast iron to form a gray cast iron base in the inner cavity, spray water mist to cool and solidify, and obtain a composite brake drum blank. S4. Preheat the composite brake drum blank, laser cladize a Ni625 layer on a gray cast iron substrate, and then laser clad a Ni50 / hBN layer on the surface of the Ni625 layer using Ni50 / hBN composite powder. Keep it warm and cool it to room temperature to obtain a wear-resistant brake drum.

2. The manufacturing process of a wear-resistant brake drum according to claim 1, characterized in that, The high-entropy alloy powder is obtained by mixing 20.5-22.5 parts by weight of aluminum powder, 15.5-17.5 parts by weight of titanium powder, 13.5-15.5 parts by weight of copper powder, 24.0-26.0 parts by weight of manganese powder, and 22.5-24.5 parts by weight of chromium powder, adding 1.5-2.5 parts by weight of cyclohexane under argon protection, ball milling for 40-45 hours at a ball-to-powder ratio of 8:1-12:1 and a rotation speed of 280-320 rpm, and drying under vacuum at 60-80℃ for 6-10 hours.

3. The manufacturing process of a wear-resistant brake drum according to claim 1, characterized in that, In step S1, 85-90 parts by mass of high-entropy alloy powder, 10-15 parts by mass of aluminum powder, 0.12-0.2 parts by mass of Sn powder, and 0.5-2 parts by mass of magnesium powder are mixed and stirred at 160-200 rpm for 6-12 hours, and then loaded into a graphite mold. Under an argon atmosphere, spark plasma sintering is performed. Under a pressure of 30-50 MPa, the temperature is first raised to 480°C at 50°C / min, and then raised to 520-550°C at 20°C / min and held for 8-12 minutes. The mixture is then transferred to a vacuum diffusion furnace, heated to 490-520°C and held for 10-20 minutes, and then cooled to room temperature. The mixture is crushed and sieved into 3-8 mm particles, and preheated at 280-320°C for 20-40 minutes to obtain the composite material.

4. The manufacturing process of a wear-resistant brake drum according to claim 1, characterized in that, In step S2, 70-80 parts by weight of aluminum ingots are added to a graphite crucible, followed by 4.0-4.6 parts by weight of zinc ingots, 4.6-5.4 parts by weight of magnesium ingots, and 0.10-0.20 parts by weight of metallic calcium particles. The mixture is heated to 740-770°C to melt and held at that temperature for 10-20 minutes. Then, 0.10-0.25 parts by weight of Al-5Ti-1B master alloy are added and stirred for 3-6 minutes. Finally, 1.0-1.5 parts by weight of refining agent are added. Continue stirring for 10-15 minutes to complete refining and degassing, remove slag, adjust the melt temperature to 730-740℃ and mechanically stir at 400-800 rpm for 10-20 minutes, while adding 8-15 parts by weight of composite material and stirring for 5-8 minutes. After standing for 2-3 minutes, introduce high-purity argon gas for 2-5 minutes for secondary degassing. Then, cast the melt at 730-740℃ and solidify it. Clean and polish to obtain a multi-element aluminum alloy shell.

5. The manufacturing process of a wear-resistant brake drum according to claim 1, characterized in that, The multi-element aluminum alloy shell comprises the following raw materials in parts by weight: 70-80 parts aluminum ingot, 4.0-4.6 parts zinc ingot, 4.6-5.4 parts magnesium ingot, 0.10-0.20 parts metallic calcium particles, 0.10-0.25 parts Al-5Ti-1B master alloy, 1.0-1.5 parts refining agent, and 8-15 parts composite material.

6. The manufacturing process of a wear-resistant brake drum according to claim 1, characterized in that, The modified protective agent is obtained by mixing 56-59 parts by weight of high borosilicate glass powder, 40-42 parts by weight of anhydrous sodium tetraborate and 1.0-2.0 parts by weight of Y3NbO7 micro powder, ball milling at 200-300 rpm for 30-60 min, and drying at 200-260℃ for 1-2 h.

7. The manufacturing process of a wear-resistant brake drum according to claim 1, characterized in that, In step S3, after cleaning and drying the inner cavity of the multi-element aluminum alloy shell, 1.0~1.5 kg / m² of [agent / material] is added according to the inner surface area of ​​the shell. 2 Modified protective agent is applied. The shell is clamped on a centrifuge and rotated at 600 r / min for 1.0 to 1.5 min to allow the modified protective agent to spread and form a continuous coating layer on the inner surface. Then, the centrifuge speed is increased to 1150 to 1200 r / min, and molten gray cast iron is poured into the inner cavity of the multi-element aluminum alloy shell at 1330 to 1350°C, which is in a high-speed rotating state, so that a gray cast iron base is formed on the inner surface. The outer multi-element aluminum alloy shell is cooled by spraying water mist to control the shell temperature at 470 to 540°C and maintain it for 8 to 10 min. Then, water cooling is continued to control the shell temperature at 50 to 120°C, and solidification is performed to obtain the composite brake drum blank.

8. The manufacturing process of a wear-resistant brake drum according to claim 1, characterized in that, In step S4, before preheating the composite brake drum blank, the composite brake drum blank is pretreated. The pretreatment steps are as follows: reheat the composite brake drum blank to 150~160℃ and keep it at that temperature for 3~5 hours, cool it to room temperature, sandblast the inner gray cast iron substrate, use Al2O3 as the sandblasting medium, and sandblasting pressure of 0.5~0.7MPa. After sandblasting, rinse with anhydrous ethanol for 5~10 minutes and dry at 100~120℃ for 30~60 minutes.

9. The manufacturing process of a wear-resistant brake drum according to claim 8, characterized in that, In step S4, the pretreated composite brake drum blank is preheated to 300°C and held for 15-30 minutes. Then, laser cladding is performed under the condition of high-purity argon gas with a flow rate of 10-15 L / min. First, Ni625 powder is used to laser clad on the gray cast iron substrate to form a Ni625 layer. Then, Ni50 / hBN composite powder is used to laser clad on the surface of the Ni625 layer to form a Ni50 / hBN layer. The blank is held at 280-320°C for 5-10 minutes and then cooled to room temperature to obtain a wear-resistant brake drum.

10. The manufacturing process of a wear-resistant brake drum according to claim 1, characterized in that, The Ni50 / hBN composite powder is composed of 95-97 parts by weight of Ni50 powder and 3-5 parts by weight of hBN powder.

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