Method for solving electrochemical corrosion of water channel of motor controller

Abstract

The invention provides a method for solving electrochemical corrosion of a water channel of a motor controller, which comprises the following steps of: adding an anticorrosive coating on a contact surface of a water channel of a main shell of an IGBT (Insulated Gate Bipolar Translator) plate of an electric vehicle, and treating an aluminum lower surface of the water channel of the main shell of the IGBT plate of the electric vehicle by adopting the methods of electroplating, anodic oxidation, chemical plating and supersonic cold spraying. The potential difference between the bottom of the copper-plated and nickel-plated IGBT above the water channel and aluminum materials on the fin column and the lower surface is reduced, so that the electrochemical corrosion reaction of the water channel of the main shell of the IGBT plate is reduced. According to the method, deposition caused by electrochemical corrosion reaction of the new energy automobile motor control water channel can be inhibited, smooth flowing of cooling liquid in the water channel is ensured, and an IGBT plate located above the water channel substrate is prevented from thermal stress damage to cause an over-temperature fault. According to the method, the IGBT plate is always in a comfortable working environment, the reliability of the IGBT plate is improved, the service life of the IGBT plate is prolonged, and the safety in the driving process is improved.

Description

Technical Field

[0001] The invention relates to the field of thermal protection of electric vehicles, and in particular to a method for solving electrochemical corrosion of water channels of IGBT boards of electric vehicles. Background Art

[0002] As the core component of new energy vehicles, the motor controller is an important component used to control the operation of the motor. Its function is to convert electrical energy into mechanical energy and monitor the operating status of the motor. The IGBT in the motor controller can convert the mains electricity into DC power to charge the battery, or convert the DC power in the battery into AC power for the motor and control the frequency conversion and voltage conversion of the AC motor. Therefore, the working state of the IGBT is directly related to the safety and reliability of new energy vehicles under various working conditions. As a high-power electronic device, IGBT generates a lot of heat when working. Coolant blockage will cause heat accumulation on the IGBT board, causing overheating failure, or uneven heating to produce temperature difference, resulting in thermal stress failure. Therefore, it is particularly important to ensure the smooth flow of coolant. The bottom and fin column of the IGBT board are nickel-plated, and the surface of the waterway substrate is made of aluminum. The nickel-made IGBT bottom plate and fin column are in contact with the aluminum surface of the waterway substrate, and the coolant between the two plates is water. When there is a potential difference between metals in a corrosive medium, an electrochemical corrosion reaction will occur. The potential of aluminum is -1.66V, and the potential of nickel is -0.23V. The bottom of the IGBT board and the fin column are connected to the waterway substrate, so that the two electrodes of the electrode potential difference are in a short-circuit state, and both metal electrodes are in the electrolyte solution (coolant). Therefore, it is very easy for electrochemical corrosion to occur on the surface of the waterway substrate and in the gap between the IGBT board fin columns to generate oxide precipitation. The accumulation of oxide precipitation will affect the flow of water and cause the IGBT board to have a temperature difference or overheat. The existing IGBT board main shell waterway does not use electroplating, anodizing, chemical plating, and supersonic cold spraying methods for electrochemical corrosion protection. The nickel bottom plate and fin column of the IGBT board and the aluminum waterway substrate are very easy to be electrochemically corroded in the coolant, resulting in corrosion blocking the flow channel in the gap between the IGBT board fin column and the surface of the waterway substrate. Summary of the invention

[0003] The present invention provides a solution to electrochemical corrosion of a water channel of a motor controller main housing, so as to solve the problem that the potential difference between the upper and lower plates of the existing IGBT board main housing water channel is high, and electrochemical corrosion is prone to occur, resulting in precipitation and blockage in the water channel, causing overheating or uneven heating of the IGBT board.

[0004] S1, considering the cooling effect, cost, environmental protection, etc., select a solution to the electrochemical corrosion of the water channel of the main housing of the motor controller, including: using electroplating, anodizing, chemical plating, and supersonic cold spraying to effectively treat the surface of the aluminum water channel substrate.

[0005] S2, when electroplating is used for treatment, a layer of other metals or alloys is attached to the surface of the aluminum waterway substrate by electrolysis. The zinc coating can be selected to treat the upper surface of the aluminum waterway substrate. The zinc coating acts as an isolation layer to effectively prevent direct contact between aluminum and nickel and reduce the occurrence of electrochemical reactions. The advantages are that the galvanizing process is mature, the cost is relatively low, and it can significantly improve the corrosion resistance of aluminum.

[0006] S3, when the surface of the waterway substrate is treated by anodizing, an oxide film is formed on the surface of the aluminum waterway substrate under an applied current, a corresponding electrolyte and specific process conditions.

[0007] S4, when chemical plating is used to treat the surface of the waterway substrate, it is a plating method that uses a suitable reducing agent to reduce the metal ions in the plating solution to metal and deposit them on the surface of the parts without an external current. It can be plated with nickel-phosphorus alloy coating or trivalent chromium passivation.

[0008] S5, when using supersonic cold spraying to treat the surface of the waterway substrate, the coating powder is shot onto the substrate surface by supersonic gas-solid two-phase airflow at room temperature or lower temperature to form a dense coating. Titanium alloy ultrasonic cold spraying can be selected.

[0009] The beneficial effects of the present invention are: using supersonic cold spraying, electroplating, chemical plating, and anodizing to add an anti-corrosion layer, reducing the electrochemical corrosion of the water channel substrate of the main shell of the IGBT board of the electric vehicle to form precipitation and block water, so that the cooling water of the IGBT board can flow smoothly, ensuring that the IGBT board is heated evenly and does not overheat, avoiding driving hazards caused by thermal runaway of the IGBT board.

[0010] Preferably, the cost of electroplating is relatively low. Electroplating is a surface plating technology, and its heat resistance is slightly inferior to that of supersonic cold spraying. Delamination or oxidation may occur in high temperature environments. The surface hardness of the electroplated coating is relatively high, but its stability to chemical corrosion and corrosive atmosphere is not as good as that of supersonic cold spraying. The corrosion resistance and wear resistance of the anodizing method are significantly improved, and the heat resistance is slightly better than that of electroplating, but compared with supersonic cold spraying, its performance in extremely high temperature environments may be limited. The cost of anodizing is relatively low, and the anodized layer has good corrosion resistance and wear resistance, but the overall stability is not as good as that of supersonic cold spraying, especially in high temperature and extreme environments. Therefore, the electroplating and anodizing methods are suitable for low-budget situations.

[0011] Preferably, supersonic cold spraying has good high temperature resistance, wear resistance and corrosion resistance, and can maintain relatively stable physical and chemical properties, extending the service life, but the equipment cost may be high.

[0012] Preferably, when the power of the IGBT board is very high, higher requirements are placed on the surface treatment, and the surface of the waterway substrate requires higher thermal stability. The surface of the waterway substrate can be anodized before supersonic cold spraying. This can better prevent the aluminum waterway substrate from contacting the nickel IGBT plate fins, and has high stability at high temperatures. However, some issues need to be noted: S1. During surface treatment, anodizing will form an oxide film on the aluminum surface, which may affect the adhesion of the supersonic cold spray coating. Therefore, before supersonic cold spraying, it is usually necessary to properly treat the anodized layer, such as roughening the surface or using a suitable adhesion layer to ensure that the coating can firmly adhere to the aluminum surface.

[0013] S2, before supersonic cold spraying, it is necessary to ensure that the surface of the anodized layer is clean and does not contain any grease, dirt or other impurities to avoid affecting the adhesion and stability of the coating.

[0014] S3, it is necessary to select supersonic cold spraying materials suitable for aluminum and anodized layers to ensure the compatibility and stability of the coating with the substrate.

[0015] S4, during the anodizing and supersonic cold spraying process, various process parameters such as processing temperature, voltage, time and coating thickness need to be strictly controlled to ensure the quality and stability of the entire processing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the dimensional drawing of the IGBT water channel substrate; Figure 2 The basic flow chart for treating the surface of waterway substrate by electroplating method; Figure 3 The basic flow chart for treating the surface of waterway substrate by electroplating method; Figure 4 It is a basic flow chart for treating the surface of waterway substrate using trivalent chromium passivation method; Figure 5 It is a basic flow chart for treating the surface of waterway substrate by supersonic cold spraying method; The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] In this embodiment, if Figure 1 As shown, it should be noted that the aluminum waterway substrate is located below the waterway, and the copper-nickel-plated IGBT template is located above the waterway. The potential of aluminum is -1.66V, and the potential of nickel is -0.23V. The bottom of the IGBT board and the fin column are connected to the waterway substrate, so that the two electrodes of the electrode potential difference are in a short-circuit state, and both metal electrodes are in the electrolyte solution (coolant), so it is very easy to electrochemically corrode on the surface of the waterway substrate and in the gap of the IGBT board fin column to generate oxide precipitation. The accumulation of oxide precipitation will affect the flow of water and cause temperature difference or overheating of the IGBT board.

[0020] In this embodiment, if Figure 2 As shown, it should be noted that when electroplating is used to treat the surface of the waterway substrate, a layer of other metals or alloys is attached to the surface of the aluminum waterway substrate by electrolysis. First, the waterway substrate is cleaned by using solvents, alkaline detergents or pickling methods to ensure that the surface of the waterway substrate is clean, free of oil and impurities. Then pickling, deoxidation treatment or chemical activation treatment is performed to enhance the adhesion of the electroplating layer. Prepare an electroplating tank, which contains a plating solution, an anode and a cathode, and ensure that the working temperature and concentration of the electroplating tank meet the requirements. According to the size and shape of the aluminum waterway substrate, set an appropriate current density to ensure the uniformity of electroplating. Place the waterway substrate in the electroplating tank to ensure that the entire surface of the waterway substrate can be covered by the plating solution to avoid oxidation. After power is turned on, the metal ions in the electrolyte deposit the metal on the upper surface of the waterway substrate to form an electroplating layer. Control the electroplating time to ensure that the thickness of the electroplating layer meets the requirements. Maintain a suitable temperature during the electroplating process to ensure the performance and reaction speed of the plating solution. A zinc plating layer can be selected to treat the upper surface of the aluminum waterway substrate. The zinc coating can act as an isolation layer to effectively prevent direct contact between aluminum and nickel, thereby reducing the occurrence of electrochemical reactions. The advantages are that the zinc plating process is mature, the cost is relatively low, and it can significantly improve the corrosion resistance of aluminum.

[0021] In this embodiment, if Figure 3As shown, it should be noted that when anodizing is used to treat the surface of the waterway substrate, an oxide film is formed on the surface of the aluminum waterway substrate under an applied current, a corresponding electrolyte and specific process conditions. Clean the waterway substrate to remove grease and impurities on the surface. Then place the waterway substrate in an electrolyte containing an oxidant, add a direct current to the electrolyte, and use the waterway substrate as an anode. The current and treatment time are appropriate. After the oxidation process is completed, soak the waterway substrate in hot water or other sealants to seal the micropores of the oxide film, thereby enhancing its corrosion resistance and hardness. Finally, clean and dry the waterway substrate to remove excess electrolyte and sealant.

[0022] Among them, in this embodiment, after the water channel substrate is treated by anodization, it is placed for 48 days with air in the water channel cavity and the system water pump coolant not circulating. The surface of the water channel substrate treated by anodization is almost unchanged and no electrochemical corrosion precipitation occurs. In contrast, the surface of the water channel substrate that has not been anodized has honeycomb corrosion and sediment.

[0023] In this embodiment, if Figure 4As shown, it should be noted that when chemical plating is used to treat the surface of the waterway substrate, it is a plating method in which metal ions in the plating solution are reduced to metals with the help of a suitable reducing agent without an external current, and then deposited on the surface of the parts. It is based on the principle of redox reaction, using a strong reducing agent in a solution containing metal ions to reduce metal ions to metals and deposit them on the surface of various materials to form a dense coating. Chemical plating technology can form a uniform and dense coating on the metal surface, improving the corrosion resistance and service life of the product. There are fewer pinholes in the chemical plating, which helps to improve the protective performance of the coating. Compared with electroplating, chemical plating does not require DC power supply equipment, which reduces production costs. There is less waste liquid discharge and less environmental pollution. It is an environmentally friendly surface treatment process. During chemical plating, the waterway substrate is first treated on the surface, including removing oil, oxides and other pollutants. Then the waterway substrate is immersed in a specific solution to produce a metal coating through a chemical reaction. Then remove the chemicals and other pollutants remaining on the surface of the coating. Finally, the plated material is dried. The nickel-phosphorus alloy coating has high corrosion resistance and good adhesion. Through chemical plating technology, a uniform and dense Ni-P coating can be formed on the aluminum surface, thereby improving the corrosion resistance of aluminum. The advantage is that the Ni-P coating is tightly combined with the aluminum substrate, which can effectively prevent the electrochemical reaction between aluminum and nickel. In addition, the Ni-P coating can also improve the mechanical properties of aluminum. Trivalent chromium passivation forms a chromium oxide film with corrosion resistance and wear resistance on the metal surface to improve the service life and performance of the metal. Trivalent chromium passivation uses the chromium ions in the trivalent chromium salt solution to undergo an oxidation-reduction reaction on the metal surface to form a dense oxide film. The steps of trivalent chromium passivation are as follows: First, the surface of the waterway substrate is cleaned and degreased to ensure that the surface is clean and free of impurities for subsequent passivation treatment. Then, the waterway substrate is immersed in a passivation solution containing trivalent chromium salts and passivated under appropriate temperature and time conditions. In this process, the temperature and pH value of the passivation solution need to be controlled to ensure the quality and stability of the generated passivation film. Generally speaking, the temperature of the passivation solution is controlled within the range of 20~40°C, and the pH value is controlled between 1.8 and 2.3. After the passivation treatment is completed, the waterway substrate is cleaned and dried and other post-processing steps are performed to ensure the quality and stability of the passivation film. Trivalent chromium passivation has little impact on the environment and human health. The oxide film formed by trivalent chromium passivation has good corrosion resistance and wear resistance. By controlling the parameters such as the temperature and pH value of the passivation solution, the quality and stability of the generated passivation film can be ensured, thereby improving the reliability and durability of the product.

[0024] In this embodiment, if Figure 5As shown, it should be noted that when the surface of the waterway substrate is treated by supersonic cold spraying, the coating powder is shot onto the surface of the substrate by supersonic gas and solid two-phase gas flow at room temperature or at a lower temperature to form a dense coating. Commonly used materials include metals, ceramics and their composite materials, which have high melting points and oxidation resistance to ensure stable operation under high temperature environments. First, the upper surface of the waterway substrate is treated by chemical or mechanical methods to ensure that its surface is clean, free of oil and oxides to ensure the adhesion of the coating. Commonly used supersonic cold spraying materials include: high temperature alloys: such as molybdenum, tungsten, chromium, nickel-based alloys, etc. Ceramic materials: such as aluminum oxide, silicon carbide, zirconium oxide, etc. Preferably, titanium alloy is used for supersonic cold spraying of the waterway substrate. The advantage is that titanium alloy, due to its high strength, good corrosion resistance, high heat resistance, etc., as a protective coating, effectively isolates the direct contact between aluminum and nickel, thereby significantly reducing the occurrence of electrochemical reactions. Ultrasonic cold spraying of titanium alloy on the aluminum surface can be expected to improve its corrosion resistance while maintaining the lightweight characteristics of aluminum. During the supersonic cold spraying process, adjust the appropriate spraying parameters, such as air flow velocity, spraying distance, spray gun angle, gas pressure and other parameters. The adjustment of these parameters will affect the thickness, density and adhesion of the coating. The selected spraying material is sprayed onto the upper surface of the waterway substrate, and the material is attached to the surface of the substrate to form a coating through the impact and thermal effect of the high-speed airflow. Continuous and uniform spraying should be maintained throughout the spraying process to ensure the uniformity and stability of the coating.

[0025] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A solution to electrochemical corrosion of the water channel of a motor controller, which uses electroplating, anodizing, chemical plating, and supersonic cold spraying methods to perform anti-corrosion treatment on the upper surface of the IGBT water channel substrate, thereby reducing the potential difference between the bottom of the nickel-plated IGBT board and the fin column and the aluminum water channel substrate, reducing the degree of electrochemical corrosion, thereby reducing electrochemical corrosion precipitation in the water channel, reducing the temperature difference of the IGBT board, and preventing thermal stress damage to the IGBT board.

2. The electrochemical corrosion method for water channel of a motor controller according to claim 1, characterized in that: When electroplating is used to treat the surface of the main shell water channel substrate, a layer of other metal or alloy is attached to the surface of the aluminum water channel substrate by electrolysis.

3. The electroplating process according to claim 2, characterized in that The zinc coating method can be selected for electroplating. The zinc coating acts as an isolation layer to effectively prevent direct contact between aluminum and nickel, thereby reducing the occurrence of electrochemical reactions.

4. The electrochemical corrosion method for water channel of a motor controller according to claim 1, characterized in that: When the surface of the main shell water channel substrate is treated by anodizing, an oxide film is formed on the upper surface of the aluminum water channel substrate under the conditions of applied current, corresponding electrolyte and specific process conditions.

5. The electrochemical corrosion method for water channel of a motor controller as claimed in claim 1, characterized in that: When chemical plating is used to treat the surface of the main shell water channel substrate, in the absence of external current, with the help of a suitable reducing agent, the metal ions in the plating solution are reduced to metal and deposited on the surface of the parts. Based on the principle of redox reaction, a strong reducing agent is used in a solution containing metal ions to reduce the metal ions to metal and deposit them on the surface of various materials to form a dense coating.

6. The chemical plating process as claimed in claim 5, characterized in that It can be plated with nickel-phosphorus alloy or passivated with trivalent chromium. Nickel-phosphorus alloy plating can form a uniform and dense Ni-P coating on the aluminum surface through chemical plating technology, thereby improving the corrosion resistance of aluminum. Its advantage is that the Ni-P coating is tightly combined with the aluminum substrate and can effectively prevent the electrochemical reaction between aluminum and nickel. Trivalent chromium passivation forms a chromium oxide film with corrosion resistance and wear resistance on the metal surface to improve the service life and performance of the metal.

7. The electrochemical corrosion method for water channel of a motor controller as claimed in claim 1, characterized in that: When ultrasonic cold spraying is used to treat the surface of the main shell water channel substrate, at room temperature or lower temperature, the coating powder is shot onto the substrate surface by supersonic gas-solid two-phase airflow to form a dense coating.

8. The ultrasonic cold spraying process as claimed in claim 7, characterized in that At room temperature or lower temperature, the coating powder is shot onto the surface of the waterway substrate by supersonic gas-solid two-phase airflow to form a dense coating. Supersonic cold spraying of the waterway substrate with titanium alloy effectively isolates the direct contact between aluminum and nickel, thereby significantly reducing the occurrence of electrochemical reactions.

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