Nitride ceramic particle reinforced electric vehicle battery pack bottom protection plate and manufacturing method thereof

Abstract

The invention discloses a nitride ceramic particle reinforced electric vehicle battery pack bottom protection plate and a manufacturing method thereof, and belongs to the field of electric vehicle battery technology and vehicle manufacturing. According to the method, a CrMoAl steel sheet is adopted, the surface of the sheet is polished to remove the oxidation condition, nitriding process treatment is conducted in a gas nitriding furnace, a sample is taken out after the sample is cooled to the room temperature along with the furnace, and the nitride ceramic particle reinforced electric automobile battery pack bottom protection plate is obtained. Ultra-deep nitriding layers are formed on the two sides of the steel plate through nitride ceramic particle reinforcement, a non-nitriding layer is formed in the middle of the steel plate, and a nitriding layer-non-nitriding layer-nitriding layer sandwich structure is formed; due to the existence of the double-layer nitriding layer and the middle non-nitriding layer, the steel plate has high hardness and obdurability at the same time, when the steel plate is applied to the electric automobile bottom protection plate, the conditions of gravel splashing, road surface fluctuation and bumping and the like caused by the external environment can be borne, and damage to a battery pack due to the conditions of bending, breakage and the like of the steel plate can be prevented.

Description

Technical Field

[0001] This invention belongs to the field of electric vehicle battery technology and vehicle manufacturing, specifically relating to a bottom guard plate for an electric vehicle battery pack reinforced with nitride ceramic particles and its manufacturing method. Background Technology

[0002] With the rapid development of electric vehicles, protecting the core component – ​​the battery pack – is of paramount importance. Typically, the battery pack is installed under the seat, on the vehicle chassis, and is usually covered to protect it and prevent fires caused by short circuits. Especially the lower part of the battery pack, being close to the ground, is frequently damaged by uneven ground and flying stones. To prevent these incidents and ensure the safety of both the battery pack and the electric vehicle, it is essential to use suitable materials to create a battery pack underbody protection plate with high hardness, high strength, wear resistance, and impact resistance.

[0003] The current battery pack bottom protection plate materials mainly include: (1) steel plate, which has the lowest cost, the strongest impact and puncture resistance, and the most mature technology. However, it is heavy, which seriously affects the range, and it is prone to corrosion. (2) aluminum alloy plate, which has the advantages of lightweight (about 60% lighter than steel), good corrosion resistance, and good impact resistance. However, it is more expensive than steel, and its hardness and strength are poor, it is easy to deform, and its resistance to extreme puncture is weaker than steel. (3) ceramic materials, which have good strength and are relatively light, but their toughness and impact resistance are poor, and they are easily broken during collisions. (4) composite material protection plates, such as glass fiber reinforced polymer, which have the advantages of lightweight, corrosion resistance, high design freedom, and structural integration. However, they are weak in their ability to resist multiple impacts and continuous wear. They were used more in early or low-end models and are now being replaced. (5) carbon fiber reinforced composite materials, which have the advantages of extreme lightweight, high specific strength, high specific modulus, and high design freedom. However, they are extremely expensive, difficult to detect after damage, and difficult to repair; they are often used in supercars and top performance cars.

[0004] Overall, traditional steel plates offer relatively high cost-effectiveness, but their weight makes them unsuitable for the operating conditions of electric vehicles, which prioritize low energy consumption and long range. While aluminum alloys are lightweight, their softness and low hardness make them prone to deformation under impacts to the battery pack's underbody, potentially causing internal short circuits and spontaneous combustion, endangering driving safety. Ceramic materials, although possessing high surface hardness, are brittle and easily break upon impact. Non-metallic materials have developed rapidly in recent years, but their high cost means they still have a long way to go in the current competitive landscape of electric vehicles, where low price and high cost-effectiveness are key competitive advantages. Summary of the Invention

[0005] In response to the current development and application of electric vehicle battery pack underbody protection plates, this invention proposes a sandwich-structured steel plate for electric vehicle battery pack underbody protection. This plate features ultra-deep nitrided layers on both sides reinforced with nitride ceramic particles, with a non-nitrided layer in the middle, creating a sandwich structure. After nitriding, this underbody protection plate has 500μm-800μm thick high-hardness and high-strength layers on both sides, providing corrosion resistance and lightweight advantages. The non-nitrided layer in the middle provides good toughness, giving the entire steel plate both high hardness and toughness. When applied to electric vehicle underbody protection plates, it can withstand external environmental factors such as flying gravel and road surface impacts, while preventing damage to the battery pack from bending or breakage. This nitride ceramic particle-reinforced sandwich-structured steel plate has significant market demand and promising application prospects as an underbody protection plate for electric vehicle battery packs. The purpose of this invention is to manufacture a sandwich-structured bottom protection steel plate for electric vehicle battery packs using nitride ceramic particles, which simultaneously possesses good strength, hardness, toughness, corrosion resistance, lightweight, and low cost to fulfill the function of a bottom protection plate for electric vehicle battery packs.

[0006] A method for manufacturing a bottom guard plate for an electric vehicle battery pack reinforced with nitride ceramic particles includes the following steps:

[0007] Using 1mm-5mm thick CrMoAl steel sheets, the surface of the sheets is polished to remove oxidation. After nitriding in a gas nitriding furnace, the samples are cooled to room temperature in the furnace and then taken out, which is the bottom protection plate of the electric vehicle battery pack reinforced with nitride ceramic particles.

[0008] Further, the CrMoAl steel sheet comprises the following components by mass percentage: Cr: 0.50%-2.00%, Al: 0.40%-1.11%, Mo: 0.10%-0.35%, Mn: 0.30%-0.60%, C: 0.17%-0.42%, Si: 0.17%-0.45%, P: ≤0.20%, S: ≤0.20%, Ni: ≤0.30%, Cu: ≤0.20%, with the balance being Fe and unavoidable impurities.

[0009] Furthermore, the nitriding process is as follows: the polished thin plate is placed in the nitriding furnace, and ammonia gas is introduced for 20-30 minutes to homogenize the atmosphere in the furnace and remove the oxidizing atmosphere in the furnace; a multi-stage nitriding process of strong nitriding-diffusion-homogenization-strong nitriding-diffusion is adopted.

[0010] Furthermore, the temperature for strong infiltration is 520℃-550℃, and the time is 20h-40h; the temperature for diffusion is 560℃-590℃, and the time is 20h-40h; the temperature for homogenization is 600℃-900℃, and the time is 2h-4h.

[0011] Furthermore, the nitride ceramic particle reinforced electric vehicle battery pack bottom protection plate is a sandwich structure of nitrided layer-non-nitrided layer-nitrided layer; nitrided layers with a thickness of 500μm-800μm are formed on both sides of the thin plate.

[0012] A bottom protection plate for an electric vehicle battery pack reinforced with nitride ceramic particles is manufactured using the above method.

[0013] An application of a nitride ceramic particle reinforced bottom protection plate for electric vehicle battery packs, wherein the nitride ceramic particle reinforced bottom protection plate is located under the battery pack and serves to support and protect the battery pack.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] This invention reinforces steel plates with nitride ceramic particles, forming an ultra-deep nitriding layer of 500μm-800μm thickness on both sides of the steel plate. Due to the formation of Fe on the sample surface during the nitriding process... 2-3 The presence of N, Fe4N phases, and ceramic reinforcing particles such as CrN and AlN significantly enhances the hardness of the CrMoAl steel plate. Simultaneously, the presence of an unnitrided layer in the core creates a sandwich structure of nitrided layer-unnitrided layer-nitrided layer. The presence of double-layer nitriding and the intermediate unnitrided layer endows the steel plate with both high hardness and toughness. Furthermore, the double-nitrided thin plate is lighter than traditional steel plates under the same performance conditions, resulting in a CrMoAl steel plate with high surface hardness and high core toughness, offering excellent cost-effectiveness. By preparing this ultra-thin steel plate with an ultra-deep nitrided layer, it is possible to meet the performance requirements of the bottom protection plate for electric vehicle battery packs while achieving lightweight design and extended range. Moreover, CrMoAl steel plates are inexpensive and can be produced in large quantities, making this research significant and valuable for application.

[0016] CrMoAl steel is a high-hardenability alloy nitriding structural steel characterized by high surface hardness and excellent wear resistance after nitriding treatment, while maintaining good strength and toughness in the matrix. It is widely used in the manufacture of mechanical parts requiring high hardness and high wear resistance. Before nitriding, its hardness is 200HV-300HV, tensile strength is 900MPa-1100MPa, elongation is ≥14%, and impact toughness is ≥78J / cm². It exhibits a good balance of strength and toughness, capable of withstanding certain impacts and loads, preventing overall breakage of parts, and also possesses a certain degree of corrosion resistance. It is suitable for automotive protection and exposed components, making it a suitable material for this invention.

[0017] By nitriding CrMoAl steel with a thickness of 1mm-5mm, nitrided layers with a thickness of 500μm-800μm are formed on both sides of the steel plate. Due to the presence of Fe in the nitrided layer... 2-3 The presence of N, Fe4N phases, and alloy nitride ceramic reinforcing particles such as AlN and CrN enables the maximum hardness of the nitrided layer to reach 1200 HV. A 0.4 mm thick unnitrided layer is left in the middle of the steel plate, forming a sandwich structure of nitrided layer-unnitrided layer-nitrided layer. This ensures that the outer side has the hardness to prevent external damage to the battery pack, while the core provides good toughness. At the same time, the 500 μm-800 μm thick ultra-deep nitrided layers on both sides can absorb the impact and collision of the battery pack bottom plate, preventing deformation and damage to the bottom plate and ensuring the safety of the battery pack. Attached Figure Description

[0018] Figure 1 A schematic diagram of the bottom protection plate of an electric vehicle battery pack reinforced with nitride ceramic particles.

[0019] Figure 2 This is a schematic diagram of the sandwich structure of the CrMoAl steel plate in Embodiment 8 of the present invention.

[0020] Figure 3 The diagram shows the nitriding process flow chart and ammonia decomposition rate variation chart of the CrMoAl steel plate in Example 8 of this invention.

[0021] Figure 4 This is an X-ray diffraction pattern of the surface layer of the CrMoAl steel plate after nitriding in Example 8 of the present invention.

[0022] Figure 5 This is a metallographic diagram of the CrMoAl steel plate after nitriding in Example 8 of the present invention.

[0023] Figure 6 This is a scanning electron microscope image of the CrMoAl steel plate after nitriding in Example 8 of the present invention.

[0024] Figure 7 This is a hardness depth distribution diagram of the CrMoAl steel plate after nitriding in Example 8 of the present invention.

[0025] Figure 8 The image shows the potential kinetics test results of the CrMoAl steel sheet before and after nitriding in Example 8 of this invention.

[0026] Figure 9 The stress-strain diagrams for the CrMoAl steel sheet before and after nitriding in Example 8 of this invention are shown. Detailed Implementation

[0027] The present invention will be described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0028] A method for manufacturing a bottom guard plate for an electric vehicle battery pack reinforced with nitride ceramic particles includes the following steps:

[0029] Using 1mm-5mm thick CrMoAl steel sheets, the surface of the sheets is polished to remove oxidation. After nitriding in a gas nitriding furnace, the samples are cooled to room temperature in the furnace and then taken out, which is the bottom protection plate of the electric vehicle battery pack reinforced with nitride ceramic particles.

[0030] Further, the CrMoAl steel sheet comprises the following components by mass percentage: Cr: 0.50%-2.00%, Al: 0.40%-1.11%, Mo: 0.10%-0.35%, Mn: 0.30%-0.60%, C: 0.17%-0.42%, Si: 0.17%-0.45%, P: ≤0.20%, S: ≤0.20%, Ni: ≤0.30%, Cu: ≤0.20%, with the balance being Fe and unavoidable impurities.

[0031] Furthermore, the nitriding process is as follows: the polished thin plate is placed in the nitriding furnace, and ammonia gas is introduced for 30 minutes to homogenize the atmosphere in the furnace and remove the oxidizing atmosphere in the furnace; a multi-stage nitriding process of strong nitriding-diffusion-homogenization-strong nitriding-diffusion is adopted.

[0032] Furthermore, the temperature for strong infiltration is 520℃-550℃, and the time is 20h-40h; the temperature for diffusion is 560℃-590℃, and the time is 20h-40h; the temperature for homogenization is 600℃-900℃, and the time is 2h-4h.

[0033] Furthermore, the nitride ceramic particle reinforced electric vehicle battery pack bottom protection plate is a sandwich structure of nitrided layer-non-nitrided layer-nitrided layer; nitrided layers with a thickness of 500μm-800μm are formed on both sides of the thin plate.

[0034] A nitride ceramic particle reinforced bottom protection plate for electric vehicle battery packs, such as Figure 1 As shown, it is manufactured using the method described above.

[0035] An application of a nitride ceramic particle reinforced bottom protection plate for electric vehicle battery packs, wherein the nitride ceramic particle reinforced bottom protection plate is located under the battery pack and serves to support and protect the battery pack.

[0036] Example 1

[0037] A method for manufacturing a nitride ceramic particle reinforced bottom guard plate for an electric vehicle battery pack includes the following steps: using a 1mm thick CrMoAl steel sheet, comprising the following components by mass percentage: Cr: 1.38%, Al: 0.95%, Mo: 0.18%, Mn: 0.45%, C: 0.36%, Si: 0.27%, P: 0.18%, S: 0.04%, Ni: 0.05%, Cu: 0.02%, with the balance being Fe and unavoidable impurities; and the surface of the CrMoAl steel sheet is then blasted. The sample is ground to remove oxidation, and then nitriding is carried out in a gas nitriding furnace. The specific nitriding process is as follows: First, the temperature is raised from room temperature to 520°C for 90 minutes and held for 20 hours (strong nitriding); then the temperature is raised from 520°C to 560°C for 10 minutes and held for 30 hours (diffusion); then the temperature is raised from 560°C to 600°C for 10 minutes and held for 2 hours (homogenization); then the temperature is lowered to 520°C for 30 minutes and held for 20 hours (strong nitriding); then the temperature is raised to 560°C for 10 minutes and held for 30 hours (diffusion); finally, the sample is cooled to room temperature with the furnace and then removed.

[0038] Example 2

[0039] A method for manufacturing a nitride ceramic particle reinforced bottom guard plate for an electric vehicle battery pack includes the following steps: using a 2mm thick CrMoAl steel sheet, comprising the following components by mass percentage: Cr: 1.38%, Al: 0.95%, Mo: 0.18%, Mn: 0.45%, C: 0.36%, Si: 0.27%, P: 0.18%, S: 0.04%, Ni: 0.05%, Cu: 0.02%, with the balance being Fe and unavoidable impurities; and the surface of the CrMoAl steel sheet is then... The sample is ground to remove oxidation, and then nitriding is carried out in a gas nitriding furnace. The specific nitriding process is as follows: First, the temperature is raised from room temperature to 520°C for 90 minutes and held for 20 hours (strong nitriding); then the temperature is raised from 520°C to 560°C for 10 minutes and held for 30 hours (diffusion); then the temperature is raised from 560°C to 600°C for 10 minutes and held for 2 hours (homogenization); then the temperature is lowered to 520°C for 30 minutes and held for 20 hours (strong nitriding); then the temperature is raised to 560°C for 10 minutes and held for 30 hours (diffusion); finally, the sample is cooled to room temperature with the furnace and then removed.

[0040] Example 3

[0041] A method for manufacturing a nitride ceramic particle reinforced bottom guard plate for an electric vehicle battery pack includes the following steps: using a 4mm thick CrMoAl steel sheet, comprising the following components by mass percentage: Cr: 1.47%, Al: 0.98%, Mo: 0.17%, Mn: 0.48%, C: 0.41%, Si: 0.30%, P: 0.15%, S: 0.03%, Ni: 0.01%, Cu: 0.01%, with the balance being Fe and unavoidable impurities; and the surface of the CrMoAl steel sheet is then blasted. The sample is ground to remove oxidation, and then nitriding is carried out in a gas nitriding furnace. The specific nitriding process is as follows: First, the temperature is raised from room temperature to 530°C for 90 minutes and held for 20 hours (strong nitriding); then the temperature is raised from 530°C to 580°C for 10 minutes and held for 30 hours (diffusion); then the temperature is raised from 580°C to 750°C for 40 minutes and held for 2 hours (homogenization); then the temperature is lowered to 530°C for 1 hour and held for 20 hours (strong nitriding); then the temperature is raised to 580°C for 10 minutes and held for 30 hours (diffusion); finally, the sample is cooled to room temperature with the furnace and then removed.

[0042] Example 4

[0043] A method for manufacturing a nitride ceramic particle-reinforced bottom guard plate for an electric vehicle battery pack includes the following steps: using a 1mm thick CrMoAl steel sheet, comprising the following components by mass percentage: Cr: 1.47%, Al: 0.98%, Mo: 0.17%, Mn: 0.48%, C: 0.41%, Si: 0.30%, P: 0.15%, S: 0.03%, Ni: 0.01%, Cu: 0.01%, with the balance being Fe and unavoidable impurities; and the surface of the CrMoAl steel sheet is then... The sample is ground to remove oxidation, and then nitriding is carried out in a gas nitriding furnace. The specific nitriding process is as follows: First, the temperature is raised from room temperature to 530°C for 90 minutes and held for 20 hours (strong nitriding); then the temperature is raised from 530°C to 580°C for 10 minutes and held for 30 hours (diffusion); then the temperature is raised from 580°C to 750°C for 40 minutes and held for 2 hours (homogenization); then the temperature is lowered to 530°C for 1 hour and held for 20 hours (strong nitriding); then the temperature is raised to 580°C for 10 minutes and held for 30 hours (diffusion); finally, the sample is cooled to room temperature with the furnace and then removed.

[0044] Example 5

[0045] A method for manufacturing a nitride ceramic particle-reinforced bottom guard plate for an electric vehicle battery pack includes the following steps: using a 2mm thick CrMoAl steel sheet, comprising the following components by mass percentage: Cr: 1.57%, Al: 0.72%, Mo: 0.19%, Mn: 0.46%, C: 0.37%, Si: 0.23%, P: 0.10%, S: 0.03%, Ni: 0.04%, Cu: 0.02%, with the balance being Fe and unavoidable impurities; and the surface of the CrMoAl steel sheet is then polished. The sample is ground to remove oxidation, and then nitriding is carried out in a gas nitriding furnace. The specific nitriding process is as follows: First, the temperature is raised from room temperature to 550°C for 90 minutes and held for 20 hours (strong nitriding); then the temperature is raised from 550°C to 590°C for 10 minutes and held for 30 hours (diffusion); then the temperature is raised from 590°C to 900°C for 50 minutes and held for 2 hours (homogenization); then the temperature is lowered to 550°C for 90 minutes and held for 20 hours (strong nitriding); then the temperature is raised to 590°C for 10 minutes and held for 30 hours (diffusion); finally, the sample is cooled to room temperature with the furnace and then removed.

[0046] Example 6

[0047] A method for manufacturing a nitride ceramic particle reinforced bottom guard plate for an electric vehicle battery pack includes the following steps: using a 4mm thick CrMoAl steel sheet, comprising the following components by mass percentage: Cr: 1.57%, Al: 0.72%, Mo: 0.19%, Mn: 0.46%, C: 0.37%, Si: 0.23%, P: 0.10%, S: 0.03%, Ni: 0.04%, Cu: 0.02%, with the balance being Fe and unavoidable impurities; and grinding the surface of the CrMoAl steel sheet. To remove oxidation, nitriding was performed in a gas nitriding furnace. The specific nitriding process was as follows: First, the temperature was raised from room temperature to 550°C for 90 minutes and held for 20 hours (strong nitriding); then the temperature was raised from 550°C to 590°C for 10 minutes and held for 30 hours (diffusion); then the temperature was raised from 590°C to 900°C for 50 minutes and held for 2 hours (homogenization); then the temperature was lowered to 550°C for 90 minutes and held for 20 hours (strong nitriding); then the temperature was raised to 590°C for 10 minutes and held for 30 hours (diffusion); finally, the sample was cooled to room temperature with the furnace and then removed.

[0048] Example 7

[0049] A method for manufacturing a nitride ceramic particle-reinforced bottom guard plate for an electric vehicle battery pack includes the following steps: using a 1mm thick CrMoAl steel sheet, comprising the following components by mass percentage: Cr: 1.41%, Al: 0.78%, Mo: 0.18%, Mn: 0.44%, C: 0.38%, Si: 0.22%, P: 0.12%, S: 0.02%, Ni: 0.02%, Cu: 0.01%, with the balance being Fe and unavoidable impurities; and the surface of the CrMoAl steel sheet is then blasted. The sample is ground to remove oxidation, and then nitriding is carried out in a gas nitriding furnace. The specific nitriding process is as follows: First, the temperature is raised from room temperature to 540°C for 90 minutes and held for 20 hours (strong nitriding); then the temperature is raised from 540°C to 570°C for 10 minutes and held for 30 hours (diffusion); then the temperature is raised from 570°C to 620°C for 20 minutes and held for 4 hours (homogenization); then the temperature is lowered to 540°C for 1 hour and held for 20 hours (strong nitriding); then the temperature is raised to 570°C for 10 minutes and held for 30 hours (diffusion); finally, the sample is cooled to room temperature with the furnace and then removed.

[0050] Example 8

[0051] A method for manufacturing a nitride ceramic particle reinforced bottom guard plate for an electric vehicle battery pack includes the following steps: using a 2mm thick CrMoAl steel sheet, comprising the following components by mass percentage: Cr: 1.41%, Al: 0.78%, Mo: 0.18%, Mn: 0.44%, C: 0.38%, Si: 0.22%, P: 0.12%, S: 0.02%, Ni: 0.02%, Cu: 0.01%, with the balance being Fe and unavoidable impurities; and grinding the surface of the CrMoAl steel sheet to remove oxidation, followed by nitriding in a gas nitriding furnace, the specific nitriding process being as follows: Figure 3 As shown, the temperature was first increased from room temperature to 540°C for 90 minutes and held for 20 hours (strong infiltration); then increased from 540°C to 570°C for 10 minutes and held for 30 hours (diffusion); then increased from 570°C to 620°C for 20 minutes and held for 4 hours (homogenization); then decreased to 540°C for 1 hour and held for 20 hours (strong infiltration); then increased to 570°C for 10 minutes and held for 30 hours (diffusion); finally, the sample was allowed to cool to room temperature with the furnace before being removed.

[0052] Figure 2 This is a schematic diagram of the sandwich structure of the CrMoAl steel sheet in this embodiment. It can be seen that there are nitrided layers on both sides of the nitrided CrMoAl steel sheet, while the middle 0.4mm part is not nitrided, thus forming a sandwich structure.

[0053] Figure 4The image shows the X-ray diffraction pattern of the surface layer of the CrMoAl steel sheet after nitriding in Example 8 of this invention. The unnitrided sample has an α-Fe phase structure, while the nitrided sample surface has an ε-Fe phase. 2-3 N phase.

[0054] Figure 5 The image shows the metallographic structure of the CrMoAl steel sheet after nitriding in Example 8 of this invention. The nitrided layer can be seen on both sides of the sample, while the middle part is the unnitrided layer.

[0055] Figure 6 This is a scanning electron microscope image of a CrMoAl steel sheet after nitriding in Example 8 of this invention. The image shows a large number of nitride precipitates, such as Fe, on both the outer and inner sides of the sample. 2-3 The N, Fe4N phase, and nitride ceramic particles such as AlN and CrN enhance its hardness.

[0056] Figure 7 This is a hardness depth distribution diagram of the CrMoAl steel sheet after nitriding in Example 8 of the present invention. The hardness depth distribution is consistent with the metallographic diagram. There are nitrided layers with a thickness of 800 μm on both sides of the sample, and the maximum hardness is 1200 HV0.3.

[0057] Figure 8 The diagram shows the potential dynamics test results of the CrMoAl steel sheet before and after nitriding in Example 8 of this invention. The unnitrided sample exhibits polarization, while the nitrided sample exhibits passivation, indicating that the sample treated by this nitriding process has good corrosion resistance.

[0058] Figure 9 The stress-strain diagrams of the CrMoAl steel sheet before and after nitriding in Example 8 of this invention are shown. The tensile strength of the unnitrided sample is 935 MPa and the elongation is 22%, while the tensile strength of the nitrided sample is 1287 MPa and the elongation is 29%. This indicates that the sample treated by this nitriding process has good strength and toughness.

Claims

1. A method for manufacturing a bottom guard plate for an electric vehicle battery pack reinforced with nitride ceramic particles, characterized in that, Includes the following steps: Using 1mm-5mm thick CrMoAl steel sheets, the surface of the sheets is polished to remove oxidation. After nitriding in a gas nitriding furnace, the samples are cooled to room temperature in the furnace and then taken out, which is the bottom protection plate of the electric vehicle battery pack reinforced with nitride ceramic particles.

2. The method for manufacturing a bottom protection plate for an electric vehicle battery pack reinforced with nitride ceramic particles according to claim 1, characterized in that, The CrMoAl steel sheet comprises the following components by mass percentage: Cr: 0.50%-2.00%, Al: 0.40%-1.11%, Mo: 0.10%-0.35%, Mn: 0.30%-0.60%, C: 0.17%-0.42%, Si: 0.17%-0.45%, P: ≤0.20%, S: ≤0.20%, Ni: ≤0.30%, Cu: ≤0.20%, with the balance being Fe and unavoidable impurities.

3. The method for manufacturing a bottom guard plate for an electric vehicle battery pack reinforced with nitride ceramic particles according to claim 1, characterized in that, The nitriding process is as follows: the polished thin plate is placed in the nitriding furnace and ammonia gas is introduced for 20-30 minutes to homogenize the atmosphere in the furnace and remove the oxidizing atmosphere in the furnace; a multi-stage nitriding process of strong nitriding-diffusion-homogenization-strong nitriding-diffusion is adopted.

4. The method for manufacturing a bottom protection plate for an electric vehicle battery pack reinforced with nitride ceramic particles according to claim 1, characterized in that, The nitride ceramic particle reinforced electric vehicle battery pack bottom protection plate is a sandwich structure of nitrided layer-non-nitrided layer-nitrided layer; nitrided layers with a thickness of 500μm-800μm are formed on both sides of the thin plate.

5. A method for manufacturing a bottom protection plate for an electric vehicle battery pack reinforced with nitride ceramic particles according to claim 3, characterized in that, The strong infiltration temperature is 520℃-550℃, and the time is 20h-40h; the diffusion temperature is 560℃-590℃, and the time is 20h-40h; the homogenization temperature is 600℃-900℃, and the time is 2h-4h.

6. A bottom protection plate for an electric vehicle battery pack reinforced with nitride ceramic particles, characterized in that, It is manufactured using the method described in any one of claims 1-5.

7. An application of a nitride ceramic particle reinforced bottom protection plate for electric vehicle battery packs, characterized in that, The nitride ceramic particle reinforced electric vehicle battery pack bottom guard plate is located under the battery pack and serves to support and protect the battery pack.

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