Hard alloy mold surface strengthening treatment system and method

Abstract

The invention belongs to the technical field of alloy molds, and particularly relates to a hard alloy mold surface strengthening treatment system and method.The method comprises the steps that impurities on the surface of a hard alloy mold are removed, then the mold is placed in a low-temperature plasma environment to activate the surface, and nanoparticles are sprayed on the mold to form an initial coating; the number of subsequent layers is determined by calculating the ratio of the initial coating to the expected total thickness, and nanoparticles are deposited in a mode that the thickness of each layer is decreased progressively. And cooling and stabilizing the structure after deposition of each layer, and enhancing atomic activity by using low-energy beam scanning to reduce interface residual stress. And finally, the surface hardness and the coating uniformity are detected, and it is ensured that the matrix crystalline phase structure is unchanged. According to the method, the negative influence of traditional high-temperature treatment is avoided, excellent coating adhesion and uniformity are achieved, the surface hardness and wear resistance of the mold are remarkably improved, the service life is prolonged, and the coating performance is optimized on the premise that the crystalline phase structure of a base material is not changed in the whole process.

Description

Technical Field

[0001] The present invention belongs to the technical field of alloy molds, and particularly relates to a surface strengthening treatment system and method for cemented carbide molds. Background Technique

[0002] During the manufacturing and maintenance of cemented carbide molds, surface strengthening treatment is one of the key steps to improve the mold performance. Traditional surface strengthening methods include physical vapor deposition (PVD), chemical vapor deposition (CVD), etc. Although these methods can enhance the surface hardness, wear resistance and corrosion resistance of the molds to a certain extent, they often have some limitations. For example, the coating process carried out under high temperature conditions may cause phase changes in the substrate material or generate large residual stresses, affecting the overall performance and service life of the molds.

[0003] In addition, it is difficult for traditional methods to achieve uniform deposition of nano-scale gradient functional coatings, which limits the further optimization of coating performance. The problem to be solved currently is how to achieve uniform deposition of nano-scale gradient functional coatings without changing the crystal phase structure of the substrate material of the cemented carbide mold and effectively suppress the residual stress concentration at the interface between the coating and the substrate. Summary of the Invention

[0004] The purpose of the present invention is to provide a surface strengthening treatment system and method for cemented carbide molds, which not only avoids the negative impacts brought by high temperature treatment, but also achieves excellent coating adhesion and uniformity, so as to solve the problems raised in the above background technique.

[0005] To achieve the above purpose, the present invention adopts the following technical scheme: A surface strengthening treatment method for cemented carbide molds, including the following steps:

[0006] Treat the cemented carbide mold to remove surface impurities; place the treated mold in a low-temperature plasma environment, adjust the environmental parameters to activate the mold surface, spray nano-particles on the activated mold surface to form an initial coating; determine the number of subsequent deposition layers by calculating the ratio of the thickness of the initial coating to the thickness of the expected gradient functional coating, and uniformly deposit additional nano-particle layers on the initial coating according to the ratio, with the thickness of each layer decreasing according to the calculation result; after each deposition, cool the mold to stabilize the newly formed coating structure, and scan the coating with a low-energy beam to enhance the atomic activity at the interface between the coating and the substrate; detect the surface hardness and coating uniformity of the mold to ensure that the coating is strengthened without changing the crystal phase structure of the substrate.

[0007] Preferably, the treating the cemented carbide mold to remove surface impurities includes:

[0008] Immerse the mold in a mixed acid solution composed of nitric acid and hydrofluoric acid with a volume ratio of 3:1. After soaking for time T1, take it out. T1 = (D / 50)^2, where D is the maximum linear dimension of the mold.

[0009] After taking out the mold, put it into an ultrasonic cleaning tank and clean it with deionized water. Set the cleaning time to T1*0.5.

[0010] Put the ultrasonically cleaned mold into an oven and dry it at a temperature T2 of 120 degrees Celsius for M minutes. M = D / 10, so that the mold is completely dry without changing its crystal phase structure.

[0011] Conduct a surface inspection on the dried mold to confirm that there are no visible impurities on the surface.

[0012] Preferably, place the treated mold in a low-temperature plasma environment and adjust the environmental parameters to activate the mold surface, including:

[0013] Put the dried mold into a low-temperature plasma reaction chamber.

[0014] Introduce a mixed gas into the reaction chamber. The mixed gas is composed of oxygen and argon in a volume ratio of 1:4. According to the maximum linear dimension D of the mold, set the gas flow rate Q1. Q1 = D*0.2.

[0015] Apply a voltage V1 to the reaction chamber to form a low-temperature plasma inside. The voltage value V1 = 100 + (D / 10).

[0016] The activation process lasts for T3 minutes. T3 = (D / 100)^2, and monitor the temperature in the reaction chamber to ensure that it does not exceed 60 degrees Celsius.

[0017] Preferably, spray nanoparticles on the surface of the activated mold to form an initial coating, including:

[0018] According to the maximum linear dimension D of the mold, calculate the required mass M1 of the nanoparticles. M1 = D*0.05.

[0019] Load the calculated mass of nanoparticles into the spraying device and set the spraying device at a position 10 centimeters away from the mold surface. Start the spraying device so that the nanoparticles are sprayed onto the surface of the mold activated by low-temperature plasma at a rate R1. R1 = M1 / T4, where T4 is the spraying time.

[0020] During the spraying process, adjust the spraying angle to 45 degrees to ensure that the nanoparticles form a uniform initial coating on the mold surface.

[0021] After the spraying is completed, the mold is subjected to preliminary curing treatment, with the heating temperature being T5 = 50 + (D / 10), and the duration being 0.5 minutes of T4.

[0022] Preferably, determining the number of subsequent deposition layers by calculating the ratio of the initial coating thickness to the expected gradient functional coating thickness includes:

[0023] Based on the maximum linear dimension D of the mold and the spraying time T4, estimate the initial coating thickness C1, C1 = D*T4 / 100;

[0024] Set the total thickness G1 of the expected gradient functional coating, calculate the ratio P1 of the initial coating thickness C1 to the expected total thickness G1, P1 = C1 / G1;

[0025] Based on the ratio P1, calculate the number of additional nanoparticle layers N1 to be added. The thickness of each layer decreases, the thickness of the first layer is C1*P1, and the thickness of each subsequent layer decreases by 80% of the previous layer. N1 = log(0.1*G1 / C1) / log(0.8);

[0026] Deposit nanoparticle layers on the initial coating in sequence according to the number of layers N1. After each layer is deposited, measure the current total thickness and adjust the deposition parameters of the next layer according to the measurement results.

[0027] Preferably, depositing additional nanoparticle layers uniformly on the initial coating according to the ratio, with the thickness of each layer decreasing according to the calculation results, includes:

[0028] According to the number of additional nanoparticle layers N1 to be added, determine the deposition thickness D1 of the first layer of nanoparticles, D1 = C1*P1;

[0029] Spray the first layer of nanoparticles onto the initial coating at a rate R2, R2 = D1 / T6, where T6 is the set deposition time for the first layer;

[0030] For each subsequent layer, its thickness Di decreases by 80% of the previous layer's thickness, Di = Di - 1*0.8; calculate the deposition rate Ri of each layer using the formula Ri = Di / Ti, where Ti is the deposition time for each layer;

[0031] After each deposition, measure the current cumulative coating thickness and adjust the deposition parameters of the next layer according to the measurement results; if the cumulative thickness does not reach the expected value, continue depositing the next layer until all N1 layers are deposited.

[0032] Preferably, after each layer is deposited, the mold is cooled to stabilize the newly formed coating structure, including:

[0033] After each layer of nanoparticles is deposited, immediately measure the mold surface temperature T7. Based on the maximum linear dimension D of the mold, set the initial cooling temperature target as Tg = 25 + (D / 10).

[0034] Move the mold to the cooling chamber. The cooling rate Vc = (T7 - Tg) / 10. During the cooling process, continuously monitor the change in the mold surface temperature. When the temperature drops to Tg, stop active cooling.

[0035] Calculate the stabilization time Ts = D * 0.5. Let the mold stand under the set environmental conditions until the coating is completely stabilized.

[0036] Preferably, using a low-energy beam to scan the coating to enhance the atomic activity at the interface between the coating and the substrate includes:

[0037] After the mold is cooled and stands for the time Ts, move the mold to the low-energy beam processing equipment. Based on the maximum linear dimension D of the mold, determine the initial beam energy E1, E1 = 5 + (D / 20).

[0038] Perform low-energy beam scanning on the coating. The scanning rate Vs = D * 0.1. During the scanning process, gradually increase the beam energy to the final value Ef, Ef = E1 + (Ts / 2), to activate the interface atoms.

[0039] After the scanning is completed, let the mold cool naturally to room temperature at the ambient temperature.

[0040] Preferably, detecting the surface hardness and coating uniformity of the mold to ensure that the coating is strengthened without changing the matrix crystal phase structure includes:

[0041] After the mold cools naturally to room temperature, select at least 5 points evenly distributed on the mold surface for surface hardness testing; based on the maximum linear dimension D of the mold, calculate the ideal hardness value Ht for each test point, Ht = 600 + (D / 2).

[0042] Measure the actual hardness Ha of the selected test points and calculate the hardness deviation rate Dh through the formula Dh = |Ht - Ha| / Ht, ensuring that the deviation rate does not exceed 10%.

[0043] Conduct a comprehensive scan of the mold to check the coating thickness and uniformity, including: for any two adjacent test areas, the coating thickness difference Dt = |T1 - T2|, where T1 and T2 are the average coating thicknesses of the two areas respectively, ensuring that the thickness difference between any two areas does not exceed 3 microns.

[0044] Detect the crystal phase structure of the mold substrate to ensure that no new crystal phases are formed and the original crystal phases have no obvious changes; if the test results meet the expectations, it is confirmed that while enhancing the surface hardness of the mold, the coating maintains the original crystal phase structure of the substrate unchanged.

[0045] On the other hand, the present invention provides a surface strengthening treatment system for cemented carbide dies, comprising:

[0046] A die treatment module for treating the cemented carbide die to remove surface impurities;

[0047] An initial coating construction module for placing the treated die in a low-temperature plasma environment, adjusting the environmental parameters to activate the die surface, and spraying nanoparticles on the activated die surface to form an initial coating;

[0048] A gradient coating construction module for determining the number of subsequent deposition layers by calculating the ratio of the thickness of the initial coating to the thickness of the expected gradient functional coating, and uniformly depositing additional nanoparticle layers on the initial coating according to the ratio, with the thickness of each layer decreasing according to the calculation result;

[0049] A coating stabilization module for cooling the die after each layer is deposited to stabilize the newly formed coating structure, and scanning the coating with a low-energy beam to enhance atomic activity at the interface between the coating and the substrate;

[0050] A verification module for detecting the surface hardness and coating uniformity of the die to ensure that the coating is strengthened without changing the crystal phase structure of the substrate.

[0051] Technical effects and advantages of the present invention: A surface strengthening treatment system and method for cemented carbide dies proposed by the present invention has the following advantages compared with the prior art:

[0052] The present invention pre-treats the die surface by using low-temperature plasma activation technology, then sprays nanoparticles on the activated surface to form an initial coating, and adds nanoparticles layer by layer in a way that the thickness decreases according to the calculation result. Finally, a low-energy beam is used to scan to enhance atomic activity and reduce the residual stress at the interface. This method not only avoids the negative effects brought by high-temperature treatment, but also achieves excellent coating adhesion and uniformity, significantly improves the surface hardness and wear resistance of the die, and extends the service life of the die. Description of the Drawings

[0053] Figure 1 It is a flowchart of a surface strengthening treatment method for a cemented carbide die of the present invention;

[0054] Figure 2 It is a block diagram of a surface strengthening treatment system for a cemented carbide die of the present invention. Detailed Embodiments

[0055] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0056] The present invention provides a surface strengthening treatment method for a cemented carbide die as shown in 1. By adopting a low-temperature plasma activation technology to pre-treat the die surface, then spraying nano-particles on the activated surface to form an initial coating, and adding nano-particles layer by layer in a way of decreasing thickness according to the calculation results, and finally using a low-energy beam to scan to enhance atomic activity and reduce interfacial residual stress.

[0057] In this embodiment, the surface strengthening treatment method for a cemented carbide die includes the following steps:

[0058] Step 1: Treat the cemented carbide die to remove surface impurities; specifically including:

[0059] Immerse the die in a mixed acid solution composed of nitric acid and hydrofluoric acid with a volume ratio of 3:1, take it out after soaking for a time T1, where T1 = (D / 50)^2, and D is the maximum linear dimension of the die; this formula is based on experimental data to ensure that dies of different sizes can be fully cleaned without being over-soaked to cause material damage.

[0060] After taking out the die, put it into an ultrasonic cleaning tank and clean it with deionized water, and set the cleaning time to T1*0.5; the cleaning time is half of T1, that is, T1*0.5, to ensure that the die is fully cleaned without being damaged due to over-cleaning.

[0061] Put the die after ultrasonic cleaning into an oven and dry it for M minutes at a temperature T2 of 120 degrees Celsius, where M = D / 10, to make the die completely dry without changing its crystal phase structure; this formula is designed to adjust the drying time according to the size of the die to achieve the best drying effect without damaging the die.

[0062] Inspect the surface of the dried die to confirm that there are no visible impurities on the surface. This step ensures the absolute cleanliness of the die surface and provides an ideal surface condition for the subsequent coating process.

[0063] Example 1

[0064] Suppose there is a cemented carbide die with a maximum linear dimension D of 100 mm.

[0065] Soaking time T1: According to the formula T1 = (D / 50)^2, substituting D = 100, we get T1 = (100 / 50)^2 = 4 minutes.

[0066] Ultrasonic cleaning time: T1 * 0.5 = 4 * 0.5 = 2 minutes.

[0067] Drying time M: According to the formula M = D / 10, substituting D = 100, we get M = 100 / 10 = 10 minutes.

[0068] According to the above parameters, first soak the mold in the mixed acid solution for 4 minutes, then ultrasonically clean it with deionized water at a frequency of 40 kHz for 2 minutes, and then dry it at 120 °C for 10 minutes. Finally, use an optical microscope to check the surface of the mold to ensure that there are no visible impurities.

[0069] Step 2: Place the treated mold in a low-temperature plasma environment and adjust the environmental parameters to activate the mold surface; specifically including:

[0070] Put the dried mold into the low-temperature plasma reaction chamber; ensure that the mold is at least 5 cm away from the inner wall of the chamber to avoid any possible interference.

[0071] Introduce a mixed gas into the reaction chamber. The mixed gas is composed of oxygen and argon in a volume ratio of 1:4; according to the maximum linear dimension D of the mold, set the gas flow rate Q1, Q1 = D * 0.2; this formula is based on experimental data to ensure that molds of different sizes can receive sufficient gas supply to promote uniform activation.

[0072] Apply a voltage V1 to the reaction chamber to form low-temperature plasma inside the chamber. The voltage value V1 = 100 + (D / 10); this formula is designed to adjust the voltage value according to the size of the mold to ensure sufficient energy for the activation process while preventing excessive voltage from causing material damage.

[0073] The activation process lasts for T3 minutes, T3 = (D / 100)^2, and monitor the temperature inside the reaction chamber to ensure that it does not exceed 60 °C. This formula is based on experimental data to ensure that molds of different sizes can receive sufficient activation time without being overheated to cause material damage.

[0074] Example 2

[0075] Suppose there is a cemented carbide mold with a maximum linear dimension D of 100 mm.

[0076] Gas flow rate Q1: According to the formula Q1 = D * 0.2, substituting D = 100, we get Q1 = 100 * 0.2 = 20 L / min.

[0077] Applied voltage V1: According to the formula V1 = 100 + (D / 10), substituting D = 100, we get V1 = 100 + (100 / 10) = 110 volts.

[0078] Activation time T3: According to the formula T3 = (D / 100)^2, substituting D = 100, we get T3 = (100 / 100)^2 = 1 minute.

[0079] According to the above parameters, first place the mold into the low-temperature plasma reaction chamber and ensure that it is at least 5 cm away from the inner wall of the chamber. Then, introduce a mixed gas composed of oxygen and argon in a volume ratio of 1:4, and set the gas flow rate to 20 L / min. Next, apply a voltage of 110 volts to the reaction chamber to form low-temperature plasma inside the chamber. Finally, the activation process lasts for 1 minute, and monitor the temperature inside the reaction chamber to ensure that it does not exceed 60 degrees Celsius.

[0080] Step 3: Spray nanoparticles on the surface of the activated mold to form an initial coating; specifically including:

[0081] According to the maximum linear dimension D of the mold, calculate the mass M1 of the required nanoparticles, M1 = D * 0.05; this formula is based on experimental data to ensure that molds of different sizes can obtain an appropriate amount of nanoparticles to achieve the best coverage effect.

[0082] Load the calculated mass of nanoparticles into the spraying device and set the spraying device at a position 10 cm away from the surface of the mold; start the spraying device to spray the nanoparticles onto the surface of the mold activated by low-temperature plasma at a rate R1, R1 = M1 / T4, where T4 is the spraying time; this formula is designed to adjust the spraying rate according to the required mass and spraying time to ensure uniform and efficient coating deposition.

[0083] During the spraying process, adjust the spraying angle to 45 degrees to ensure that the nanoparticles form a uniformly distributed initial coating on the surface of the mold; the specific angle helps the nanoparticles to be more evenly distributed on the surface of the mold, avoiding local over-thickness or under-thickness, thereby improving the consistency and adhesion of the coating.

[0084] After spraying, perform a preliminary curing treatment on the mold, with the heating temperature T5 = 50 + (D / 10) and the duration of T4 * 0.5 minutes. This formula is designed to adjust the heating temperature according to the size of the mold to ensure sufficient curing without damaging the material.

[0085] Example 3

[0086] Suppose there is a cemented carbide mold with a maximum linear dimension D of 100 mm.

[0087] Required mass of nanoparticles M1: According to the formula M1 = D * 0.05, substituting D = 100, we get M1 = 100 * 0.05 = 5 grams.

[0088] Spraying rate R1: Assuming the spraying time is T4 = 5 minutes, then according to the formula R1 = M1 / T4, substituting M1 = 5 and T4 = 5, we get R1 = 5 / 5 = 1 gram / minute.

[0089] Initial curing temperature T5: According to the formula T5 = 50 + (D / 10), substituting D = 100, we get T5 = 50 + (100 / 10) = 60 degrees Celsius.

[0090] Initial curing time: T4 * 0.5 = 5 * 0.5 = 2.5 minutes.

[0091] According to the above parameters, first calculate the required mass of nanoparticles as 5 grams based on the mold size and load it into the spraying device. Then, set the spraying device at a position 10 centimeters away from the mold surface, start the spraying device, and spray nanoparticles onto the mold surface at a rate of 1 gram / minute. During the spraying process, keep the spraying angle at 45 degrees. After spraying, perform an initial curing treatment on the mold by heating it at 60 degrees Celsius for 2.5 minutes.

[0092] Step 4: Determine the number of subsequent deposition layers by calculating the ratio of the initial coating thickness to the expected gradient functional coating thickness; specifically including:

[0093] Based on the maximum linear dimension D of the mold and the spraying time T4, estimate the initial coating thickness C1, C1 = D * T4 / 100; this formula is based on experimental data to ensure accurate estimation of the initial coating thickness for molds of different sizes and spraying times. By accurately calculating the thickness of the initial coating, accurate basic data can be provided for subsequent coating processes to ensure that the final coating meets the design requirements.

[0094] Set the total thickness G1 of the expected gradient functional coating, calculate the ratio P1 of the initial coating thickness C1 to the expected total thickness G1, P1 = C1 / G1; this ratio is used to guide the deposition of nanoparticle layers in subsequent steps to ensure that the thickness of each layer gradually decreases until the design thickness is reached.

[0095] Based on the ratio P1, calculate the number of additional nanoparticle layers N1 to be added. The thickness of each layer decreases, the thickness of the first layer is C1 * P1, and the thickness of each subsequent layer decreases by 80% of the previous layer. N1 = log(0.1 * G1 / C1) / log(0.8); by calculating the required number of layers and using the method of decreasing thickness, a uniform and continuous gradient functional coating can be achieved, enhancing the overall performance of the coating.

[0096] Deposit nanoparticle layers on the initial coating successively according to the number of layers N1. After each layer is deposited, measure the current total thickness and adjust the deposition parameters of the next layer based on the measurement results. Monitor and adjust the deposition parameters of each layer in real time to ensure the consistency of the coating thickness and the overall performance, and avoid uneven or weak links caused by cumulative errors.

[0097] Example 4

[0098] Suppose there is a cemented carbide die with a maximum linear dimension D of 100 mm, an injection time of T4 = 5 minutes, and an expected total thickness G1 of the gradient functional coating of 50 μm.

[0099] Initial coating thickness C1: According to the formula C1 = D * T4 / 100, substituting D = 100 and T4 = 5, we get C1 = 100 * 5 / 100 = 5 μm.

[0100] Ratio P1: According to the formula P1 = C1 / G1, substituting C1 = 5 and G1 = 50, we get P1 = 5 / 50 = 0.1.

[0101] Additional number of layers N1: According to the formula N1 = log(0.1 * G1 / C1) / log(0.8), substituting G1 = 50 and C1 = 5, we get N1 = log(0.1 * 50 / 5) / log(0.8) ≈ 7 layers (rounded to the nearest integer).

[0102] According to the above parameters, first estimate the initial coating thickness to be 5 μm, then set the expected total thickness to 50 μm, and calculate the ratio of the initial coating thickness to the expected total thickness as 0.1. Based on this ratio, calculate that the number of additional nanoparticle layers to be added is about 7 layers. The thickness of each layer decreases, the thickness of the first layer is C1 * P1 = 5 * 0.1 = 0.5 μm, and the thickness of each subsequent layer decreases by 80% of the previous layer. Finally, deposit nanoparticle layers on the initial coating successively according to the calculated number of layers, measure the current total thickness after each layer is deposited, and adjust the deposition parameters of the next layer according to the measurement results to ensure that the final coating thickness meets the design requirements.

[0103] Step 5: Deposit additional nanoparticle layers uniformly on the initial coating according to the ratio, and the thickness of each layer decreases according to the calculation results; specifically including:

[0104] Determine the deposition thickness D1 of the first layer of nanoparticles according to the number of additional nanoparticle layers N1 to be added, D1 = C1 * P1; by accurately calculating the thickness of the first layer, ensure that each subsequent layer can decrease at a predetermined ratio, thereby forming a uniform and continuous gradient functional coating.

[0105] The first layer of nanoparticles is sprayed onto the initial coating at a rate R2, where R2 = D1 / T6 and T6 is the set deposition time for the first layer; this formula is designed to adjust the spraying rate based on the desired thickness and deposition time to ensure uniform and efficient coating deposition.

[0106] For each subsequent layer, its thickness Di decreases by 80% of the thickness of the previous layer, Di = Di-1 * 0.8; the deposition rate Ri for each layer is calculated using the formula Ri = Di / Ti, where Ti is the deposition time for each layer; by gradually decreasing the thickness of each layer, a uniform and continuous gradient functional coating can be achieved, enhancing the overall performance and adhesion of the coating.

[0107] After each deposition, the current cumulative coating thickness is measured, and the deposition parameters for the next layer are adjusted based on the measurement results; if the cumulative thickness does not reach the expected value, the deposition of the next layer number continues until the deposition of all N1 layers is completed. The deposition parameters for each layer are monitored and adjusted in real time to ensure the consistency of the coating thickness and the overall performance, and to avoid uneven or weak links caused by cumulative errors.

[0108] Example Five

[0109] Suppose there is a cemented carbide die with a maximum linear dimension D of 100 mm, a spraying time of T4 = 5 minutes, and an expected total thickness G1 of the gradient functional coating of 50 microns. According to the previous calculations, the initial coating thickness C1 is 5 microns, the ratio P1 is 0.1, and the number of additional nanoparticle layers N1 to be added is approximately 7 layers.

[0110] Thickness D1 of the first layer: According to the formula D1 = C1 * P1, substituting C1 = 5 and P1 = 0.1, we get D1 = 5 * 0.1 = 0.5 microns.

[0111] Deposition rate R2 of the first layer: Suppose the deposition time for the first layer is T6 = 2 minutes, then according to the formula R2 = D1 / T6, substituting D1 = 0.5 and T6 = 2, we get R2 = 0.5 / 2 = 0.25 g / minute.

[0112] Thickness D2 of the second layer: According to the formula D2 = D1 * 0.8, substituting D1 = 0.5, we get D2 = 0.5 * 0.8 = 0.4 microns.

[0113] Deposition rate R2 of the second layer: Suppose the deposition time for the second layer is T2 = 2 minutes, then according to the formula R2 = D2 / T2, substituting D2 = 0.4 and T2 = 2, we get R2 = 0.4 / 2 = 0.2 g / minute.

[0114] According to the above parameters, first determine the deposition thickness of the first layer of nanoparticles to be 0.5 microns, and spray it onto the initial coating at a rate of 0.25 grams per minute for a deposition time of 2 minutes. Subsequently, the thickness of each subsequent layer decreases by 80% of the previous layer, and the deposition of subsequent layers is carried out in sequence. After each deposition, measure the current cumulative coating thickness and adjust the deposition parameters of the next layer according to the measurement results until the deposition of all 7 layers is completed.

[0115] Step Six: After the deposition of each layer, cool the mold to stabilize the newly formed coating structure; specifically including:

[0116] After the deposition of each layer of nanoparticles is completed, immediately measure the surface temperature T7 of the mold. Based on the maximum linear dimension D of the mold, set the initial cooling temperature target as Tg = 25 + (D / 10); by measuring the surface temperature of the mold and setting an appropriate cooling target temperature, it can be ensured that during the cooling process of the mold, stress concentration or cracking phenomena will not occur inside the coating due to too rapid temperature changes.

[0117] Move the mold to the cooling chamber, with a cooling rate Vc = (T7 - Tg) / 10. During the cooling process, continuously monitor the change in the surface temperature of the mold. When the temperature drops to Tg, stop active cooling; an appropriate cooling rate helps reduce the residual stress inside the coating and prevent delamination or cracking at the interface between the coating and the substrate, thereby improving the adhesion and stability of the coating.

[0118] Calculate the stabilization time Ts = D * 0.5, and let the mold stand under the set environmental conditions until the coating is completely stabilized. Real-time monitoring of the temperature and stopping active cooling when the target temperature is reached can prevent changes in material properties caused by overcooling, and maintaining an appropriate environmental humidity helps enhance the stability of the coating.

[0119] Example Six

[0120] Suppose there is a cemented carbide mold with a maximum linear dimension D of 100 millimeters.

[0121] Initial cooling temperature target Tg: According to the formula Tg = 25 + (D / 10), substituting D = 100, we get Tg = 25 + (100 / 10) = 35 degrees Celsius.

[0122] Cooling rate Vc: Suppose the surface temperature T7 of the mold is 80 degrees Celsius. Then, according to the formula Vc = (T7 - Tg) / 10, substituting T7 = 80 and Tg = 35, we get Vc = (80 - 35) / 10 = 4.5 degrees Celsius per minute.

[0123] Stabilization time Ts: According to the formula Ts = D * 0.5, substituting D = 100, we get Ts = 100 * 0.5 = 50 minutes.

[0124] According to the above parameters, first, immediately after each layer of nanoparticle deposition is completed, the temperature of the mold surface is measured. Based on the maximum linear dimension of the mold being 100 mm, the initial cooling temperature target is set at 35 degrees Celsius. Then, the mold is moved to the cooling chamber with a cooling rate of 4.5 degrees Celsius per minute, and the change in the mold surface temperature is continuously monitored during the cooling process. When the temperature drops to 35 degrees Celsius, active cooling is stopped. Finally, the stabilization time is calculated to be 50 minutes, and the mold is left to stand under the set environmental conditions until the coating is completely stable. This method ensures the stability of the coating after deposition, reduces the residual stress inside the coating, and enhances the bonding force between the coating and the substrate.

[0125] Step 7: Use a low-energy beam to scan the coating to enhance the atomic activity at the interface between the coating and the substrate; specifically including:

[0126] After the mold has completed cooling and the standing time Ts, the mold is moved to the low-energy beam processing equipment. Based on the maximum linear dimension D of the mold, the initial beam energy E1 is determined, where E1 = 5 + (D / 20); this formula is used to adjust the initial beam energy according to the size of the mold to ensure that molds of different sizes can receive appropriate energy input to achieve the best atomic activation effect.

[0127] The coating is scanned with a low-energy beam at a scanning rate Vs = D * 0.1. During the scanning process, the beam energy is gradually increased to the final value Ef, where Ef = E1 + (Ts / 2), to activate the interface atoms; this formula is based on experimental data to ensure that molds of different sizes can obtain an appropriate scanning rate to achieve a uniform energy distribution. Gradually increasing the beam energy can more effectively activate the interface atoms while preventing material damage or structural changes caused by excessive energy input, ensuring a good bonding force between the coating and the substrate.

[0128] After the scanning is completed, the mold is allowed to cool naturally to room temperature at the ambient temperature. During this period, the state of the interface between the coating and the substrate is continuously monitored to ensure that the atomic activity is sufficient and stable, thereby enhancing the coating adhesion and structural stability while keeping the crystal phase structure of the mold unchanged.

[0129] Example 7

[0130] Suppose there is a cemented carbide mold with a maximum linear dimension D of 100 mm and a standing time of Ts = 50 minutes.

[0131] Initial beam energy E1: According to the formula E1 = 5 + (D / 20), substituting D = 100, we get E1 = 5 + (100 / 20) = 10 keV.

[0132] Scanning rate Vs: According to the formula Vs = D * 0.1, substituting D = 100, we get Vs = 100 * 0.1 = 10 mm / s.

[0133] Final beam energy Ef: According to the formula Ef = E1+(Ts / 2), substituting E1 = 10 and Ts = 50, we get Ef = 10+(50 / 2)=35 keV.

[0134] According to the above parameters, after the mold is cooled and left standing for 50 minutes, it is moved to a low-energy beam processing device. Based on the maximum linear dimension of the mold being 100 mm, the initial beam energy is set to 10 keV. Then, a low-energy beam scan is performed on the coating at a scan rate of 10 mm / s. During the scan, the beam energy is gradually increased to the final value of 35 keV to further activate the interface atoms. Finally, after the scan is completed, the mold is allowed to cool naturally to room temperature at ambient temperature.

[0135] Step Eight: Detect the surface hardness of the mold and the uniformity of the coating to ensure that the coating is strengthened without changing the matrix crystal phase structure; specifically including:

[0136] After the mold has cooled naturally to room temperature, at least 5 points evenly distributed on the surface of the mold are selected for surface hardness testing; based on the maximum linear dimension D of the mold, the ideal hardness value Ht of each test point is calculated, Ht = 600+(D / 2); this formula is used to adjust the expected hardness value according to the size of the mold to ensure that molds of different sizes can meet the expected hardness standards.

[0137] Measure the actual hardness Ha of the selected test points and calculate the hardness deviation rate Dh through the formula Dh = |Ht - Ha| / Ht to ensure that the deviation rate does not exceed 10%; by calculating the hardness deviation rate, the difference between the actual hardness and the expected hardness can be evaluated to ensure that the coating can effectively increase the surface hardness of the mold without exceeding the design range.

[0138] Perform a comprehensive scan of the mold to check the coating thickness and uniformity, including: for any two adjacent test areas, the coating thickness difference Dt = |T1 - T2|, where T1 and T2 are the average coating thicknesses of the two areas respectively, to ensure that the thickness difference between any two areas does not exceed 3 microns; this formula is used to quantify the coating thickness difference to ensure that the thickness change between areas is within the allowable range to achieve uniform coating coverage.

[0139] Detect the matrix crystal phase structure of the mold to ensure that no new crystal phases are formed and the original crystal phases show no obvious changes; if the test results meet the expectations, it is confirmed that while enhancing the surface hardness of the mold, the coating maintains the original crystal phase structure of the matrix unchanged.

[0140] Example Eight

[0141] Suppose there is a cemented carbide mold with a maximum linear dimension D of 100 mm.

[0142] Ideal hardness value Ht: According to the formula Ht = 600 + (D / 2), substituting D = 100, we get Ht = 600 + (100 / 2) = 650 Vickers hardness.

[0143] Hardness deviation rate Dh: Suppose the actual hardness Ha at a certain test point is 640 Vickers hardness. Then, according to the formula Dh = |Ht - Ha| / Ht, substituting Ht = 650 and Ha = 640, we get Dh = |650 - 640| / 650 ≈ 0.0154 (about 1.54%).

[0144] Coating thickness difference Dt: Suppose the average coating thicknesses of two adjacent test areas are T1 = 5 μm and T2 = 4.8 μm respectively. Then, according to the formula Dt = |T1 - T2|, we get Dt = |5 - 4.8| = 0.2 μm.

[0145] According to the above parameters, after the mold naturally cools down to room temperature, at least 5 points evenly distributed on the mold surface are selected for surface hardness testing. Based on the maximum linear dimension of the mold being 100 mm, the ideal hardness value of each test point is calculated to be 650 Vickers hardness. The actual hardness of the selected test points is measured using a microhardness tester. For example, the actual hardness of a certain point is 640 Vickers hardness, and the calculated hardness deviation rate is about 1.54%, meeting the requirement of being less than 10%. Next, the mold is scanned comprehensively to check the coating thickness and uniformity, and it is found that the coating thickness difference between any two adjacent test areas is 0.2 μm, far lower than the standard of 3 μm. Finally, the X-ray diffraction analysis method is used to detect the crystal phase structure of the mold substrate. The results show that no new crystal phases are formed and the original crystal phases have no obvious changes, confirming that while the coating enhances the surface hardness of the mold, it maintains the original crystal phase structure of the substrate unchanged. This method ensures the effectiveness and stability of the coating and improves the overall performance of the mold.

[0146] On the other hand, the present invention proposes a surface strengthening treatment system for cemented carbide molds, as Figure 2 shown, including:

[0147] A mold treatment module for treating the cemented carbide mold to remove surface impurities;

[0148] An initial coating construction module for placing the treated mold in a low-temperature plasma environment, adjusting the environmental parameters to activate the mold surface, and spraying nanoparticles on the activated mold surface to form an initial coating;

[0149] A gradient coating construction module for determining the number of subsequent deposition layers by calculating the ratio of the initial coating thickness to the expected gradient functional coating thickness, and uniformly depositing additional nanoparticle layers on the initial coating according to the ratio, with the thickness of each layer decreasing according to the calculation results;

[0150] A coating stabilization module, which is used to cool the mold after each layer deposition to stabilize the newly formed coating structure, and scan the coating with a low-energy beam to enhance the atomic activity at the interface between the coating and the substrate;

[0151] A verification module, which is used to detect the surface hardness of the mold and the coating uniformity to ensure that the coating is strengthened without changing the crystal phase structure of the substrate.

[0152] In addition, each of the above modules is also used to implement other steps of the above-mentioned surface strengthening treatment method for cemented carbide molds when executed, which will not be elaborated one by one here.

[0153] In summary, the present invention pre-treats the mold surface by adopting the low-temperature plasma activation technology, then sprays nanoparticles on the activated surface to form an initial coating, adds nanoparticles layer by layer in a way of decreasing thickness according to the calculation results, and finally scans with a low-energy beam to enhance atomic activity and reduce the interfacial residual stress. This method not only avoids the negative impacts brought by high-temperature treatment, but also achieves excellent coating adhesion and uniformity, significantly improves the surface hardness and wear resistance of the mold, and extends the service life of the mold.

[0154] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for surface strengthening treatment of cemented carbide dies, characterized in that, The steps include: Treat the cemented carbide die to remove surface impurities; Place the treated die in a low-temperature plasma environment, adjust the environmental parameters to activate the die surface, and spray nanoparticles on the activated die surface to form an initial coating; Determine the number of subsequent deposition layers by calculating the ratio of the thickness of the initial coating to the thickness of the expected gradient functional coating. According to the ratio, uniformly deposit additional nanoparticle layers on the initial coating, and the thickness of each layer decreases according to the calculation result; After each layer is deposited, cool the die to stabilize the newly formed coating structure, and scan the coating with a low-energy beam to enhance the atomic activity at the interface between the coating and the substrate; Detect the surface hardness and coating uniformity of the die to ensure that the coating is strengthened without changing the crystal phase structure of the substrate.

2. The surface strengthening treatment method of a cemented carbide die according to claim 1, wherein: The treatment of the cemented carbide die to remove surface impurities includes: Immerse the die in a mixed acid solution composed of nitric acid and hydrofluoric acid with a volume ratio of 3:1, take it out after soaking for time T1, where T1 = (D / 50)^2 and D is the maximum linear dimension of the die; After taking out the die, put it into an ultrasonic cleaning tank and clean it with deionized water. The cleaning time is set to T1*0.5; Put the die after ultrasonic cleaning into an oven and dry it at a temperature T2 of 120 °C for M minutes, where M = D / 10, to make the die completely dry without changing its crystal phase structure; Conduct a surface inspection on the dried die to confirm that there are no visible impurities on the surface.

3. A surface strengthening treatment method for a cemented carbide die according to claim 2, characterized in that: The placement of the treated die in a low-temperature plasma environment and the adjustment of environmental parameters to activate the die surface include: Put the dried die into a low-temperature plasma reaction chamber; Introduce a mixed gas into the reaction chamber. The mixed gas is composed of oxygen and argon in a volume ratio of 1:4; according to the maximum linear dimension D of the die, set the gas flow rate Q1, where Q1 = D*0.2; Apply a voltage V1 to the reaction chamber to form a low-temperature plasma in the chamber, and the voltage value V1 = 100 + (D / 10); The activation process lasts for T3 minutes, where T3 = (D / 100)^2, and monitor the temperature in the reaction chamber to ensure that it does not exceed 60 °C.

4. A surface strengthening treatment method for a cemented carbide die according to claim 3, characterized in that: The spraying of nanoparticles on the activated die surface to form an initial coating includes: According to the maximum linear dimension D of the die, calculate the mass M1 of the required nanoparticles, where M1 = D*0.05; Load the calculated mass of nanoparticles into the spraying device and set the spraying device at a position 10 cm away from the die surface; start the spraying device to spray the nanoparticles onto the die surface activated by low-temperature plasma at a rate R1, where R1 = M1 / T4 and T4 is the spraying time; During the spraying process, adjust the spraying angle to 45 degrees to ensure that the nanoparticles form a uniformly distributed initial coating on the die surface; After spraying, conduct a preliminary curing treatment on the die, with a heating temperature of T5 = 50 + (D / 10) and a duration of T4*0.5 minutes.

5. A surface strengthening treatment method for a cemented carbide mold according to claim 4, characterized in that: The determination of the number of subsequent deposition layers by calculating the ratio of the thickness of the initial coating to the thickness of the expected gradient functional coating includes: Based on the maximum linear dimension D of the mold and the spraying time T4, estimate the initial coating thickness C1, where C1 = D * T4 / 100; Set the total thickness G1 of the expected gradient functional coating, and calculate the ratio P1 of the initial coating thickness C1 to the expected total thickness G1, where P1 = C1 / G1; Based on the ratio P1, calculate the number of additional nanoparticle layers N1 to be added. The thickness of each layer decreases, with the thickness of the first layer being C1 * P1, and the thickness of each subsequent layer decreasing by 80% of the previous layer. N1 = log(0.1 * G1 / C1) / log(0.8); According to the number of layers N1, sequentially deposit nanoparticle layers on the initial coating. After each layer is deposited, measure the current total thickness and adjust the deposition parameters of the next layer according to the measurement results.

6. A surface strengthening treatment method for a cemented carbide die according to claim 5, characterized in that: Deposit additional nanoparticle layers uniformly on the initial coating according to the ratio. The thickness of each layer decreases according to the calculation results, including: Determine the deposition thickness D1 of the first layer of nanoparticles according to the number of additional nanoparticle layers N1 to be added, where D1 = C1 * P1; Spray the first layer of nanoparticles onto the initial coating at a rate R2, where R2 = D1 / T6, and T6 is the set deposition time for the first layer; For each subsequent layer, its thickness Di decreases by 80% of the previous layer's thickness, where Di = Di - 1 * 0.8; calculate the deposition rate Ri of each layer using the formula Ri = Di / Ti, where Ti is the deposition time for each layer; After each deposition, measure the current cumulative coating thickness and adjust the deposition parameters of the next layer according to the measurement results; if the cumulative thickness does not reach the expected value, continue depositing the next layer until all N1 layers are deposited.

7. A surface strengthening treatment method for a cemented carbide die according to claim 6, characterized in that: After each layer is deposited, cool the mold to stabilize the newly formed coating structure, including: Immediately measure the surface temperature T7 of the mold after each layer of nanoparticles is deposited. Based on the maximum linear dimension D of the mold, set the initial cooling temperature target as Tg = 25 + (D / 10); Move the mold to the cooling chamber, with a cooling rate Vc = (T7 - Tg) / 10. During the cooling process, continuously monitor the change in the mold surface temperature. When the temperature drops to Tg, stop active cooling; Calculate the stabilization time Ts = D * 0.5, and let the mold stand under the set environmental conditions until the coating is completely stabilized.

8. A surface strengthening treatment method for a cemented carbide die according to claim 7, characterized in that: Use a low-energy beam to scan the coating to enhance the atomic activity at the interface between the coating and the substrate, including: After the mold has cooled and stood for the time Ts, move the mold into the low-energy beam processing equipment. Based on the maximum linear dimension D of the mold, determine the initial beam energy E1, where E1 = 5 + (D / 20); Perform low-energy beam scanning on the coating, with a scanning rate Vs = D * 0.

1. During the scanning process, gradually increase the beam energy to the final value Ef, where Ef = E1 + (Ts / 2), to activate the interface atoms; After the scanning is completed, let the mold naturally cool to room temperature at the ambient temperature.

9. A surface strengthening treatment method for a cemented carbide die according to claim 8, characterized in that: Detect the surface hardness of the mold and the coating uniformity to ensure that the coating is strengthened without changing the crystal phase structure of the substrate, including: After the mold naturally cools down to room temperature, select at least 5 points evenly distributed on the mold surface for surface hardness testing; based on the maximum linear dimension D of the mold, calculate the ideal hardness value Ht for each test point, Ht = 600 + (D / 2). Measure the actual hardness Ha of the selected test points, and calculate the hardness deviation rate Dh through the formula Dh = |Ht - Ha| / Ht, ensuring that the deviation rate does not exceed 10%. Conduct a comprehensive scan of the mold to check the coating thickness and uniformity, including: for any two adjacent test areas, the coating thickness difference Dt = |T1 - T2|, where T1 and T2 are the average coating thicknesses of the two areas respectively, ensuring that the thickness difference between any two areas does not exceed 3 microns. Detect the crystal phase structure of the mold substrate to ensure that no new crystal phases are formed and the original crystal phases show no obvious changes; if the test results meet the expectations, it is confirmed that while the coating enhances the surface hardness of the mold, it maintains the original crystal phase structure of the substrate unchanged.

10. A cemented carbide die surface strengthening treatment system for implementing the method according to any one of claims 1-9, characterized in that, Including: A mold treatment module for treating the cemented carbide mold to remove surface impurities. An initial coating construction module for placing the treated mold in a low-temperature plasma environment, adjusting the environmental parameters to activate the mold surface, and spraying nanoparticles on the activated mold surface to form an initial coating. A gradient coating construction module for determining the number of subsequent deposition layers by calculating the ratio of the initial coating thickness to the expected gradient functional coating thickness, and uniformly depositing additional nanoparticle layers on the initial coating according to the ratio, with the thickness of each layer decreasing according to the calculation results. A coating stabilization module for cooling the mold after each layer deposition to stabilize the newly formed coating structure, and scanning the coating with a low-energy beam to enhance the atomic activity at the interface between the coating and the substrate. A verification module for detecting the surface hardness and coating uniformity of the mold to ensure that the coating is strengthened without changing the crystal phase structure of the substrate.

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