Preparation method for laser cladding of iron-based alloy wear-resistant coating on surface of automobile brake disc

Abstract

The invention discloses a preparation method for laser cladding of an iron-based alloy wear-resistant coating on the surface of an automobile brake disc, which comprises the following steps: (1) before cladding, putting iron-based alloy powder into a drying oven at 60 DEG C and drying for 120 minutes; (2) pretreating a matrix sample, removing rust and an oxide layer on the surface, cleaning the surface with absolute ethyl alcohol, and wiping to keep the surface dry; and (3) setting cladding process parameters, wherein the cladding process parameters comprise laser power, powder feeding amount, scanning speed, lap joint rate and scanning linear speed. And (4) a cladding experiment is started, and a cladding scanning path and mode are set, wherein the cladding scanning path and mode comprise a single-channel coating, a multi-channel lap joint coating and a whole-surface brake disc. And (5) after cladding is finished, waiting for natural cooling of the brake disc. The iron-based powder is used for preparing the coating on the surface of the automobile brake disc, technological parameters are optimized, the cladding procedure is simplified, the powder cost is low, the prepared coating is good in performance, and a single-layer coating scheme is provided for strengthening and repairing the brake disc.

Description

Technical Field

[0001] The invention belongs to the technical field of laser cladding processing, and in particular relates to a method for preparing a laser-clad iron-based alloy wear-resistant coating on the surface of an automobile brake disc. Background Art

[0002] With the rapid development of China's new energy vehicle industry, cars are becoming increasingly common in every household. Automotive brake discs are a key component of the automotive braking system and a crucial factor in ensuring travel safety. The braking process works by squeezing the brake disc against the brake pads, generating a braking torque through the frictional resistance between the contact surfaces, thereby decelerating the vehicle. Automotive brake discs are primarily made of gray cast iron, which is susceptible to oxidation and wear. After prolonged use, the friction coefficient of gray cast iron becomes unstable, leading to a decrease in braking performance and compromising driving safety. When a brake disc reaches its service life, it must be completely replaced. Currently, used brake discs are simply disposed of as scrap, resulting in low metal utilization. Furthermore, the upcoming Euro 7 standard imposes stricter requirements on particulate matter emissions during braking. Therefore, this research focuses on the repair and strengthening of automotive brake discs. Among various surface additive manufacturing technologies, laser cladding offers advantages such as a small heat-affected zone, a dense coating, and high bonding strength, making it suitable for the repair and strengthening of automotive brake disc surfaces.

[0003] Patent publication number CN119040883A reports a laser-clad, high-hardness, wear-resistant coating on the surface of automotive brake discs and its preparation method. The coating's required powder composition is as follows: NiCr-Cr-3C-2 composite powder and 15-25wt% AlN powder. Patent publication number CN114717549B reports a laser-cladding method for gray cast iron brake discs, using a multi-component rare earth-doped nickel-based tungsten carbide alloy powder. Patent publication number CN119433535B reports a method for preparing a layer of metallized TiC powder by cladding on 316 stainless steel surfaces. Patent publication number CN114892165A reports a process for producing brake disc coatings by ultra-high-speed cladding, where the wear-resistant layer is a nickel-based powder containing WC particles.

[0004] In summary, the coatings prepared on the surface of cast iron using laser cladding technology are usually carbide composite coatings or multi-layer gradient coatings. However, the cost of powder and processing is too high for the value of the brake disc itself, and the laser cladding equipment is expensive, making it difficult to carry out large-scale mass production. Summary of the Invention

[0005] In order to reduce the cost of powder and processing while taking into account good wear resistance and corrosion resistance, the present invention provides a method for preparing a laser-clad iron-based alloy wear-resistant coating on the surface of an automobile brake disc. An iron-based alloy powder coating and cladding process parameters have been developed, which cleverly solves this problem.

[0006] This application is achieved through the following technical solutions:

[0007] A method for preparing a laser-clad iron-based alloy wear-resistant coating on the surface of an automobile brake disc comprises the following steps:

[0008] Step (1) Before cladding, the iron-based alloy powder is placed in an oven for drying to ensure that the powder remains dry during the cladding process;

[0009] Step (2) Pretreatment of the substrate sample: Before cladding, the brake disc substrate is first polished using an angle grinder to remove surface rust and oxide layers while retaining a certain degree of surface roughness to avoid loss caused by laser energy reflection;

[0010] Step (3) setting cladding process parameters, fixed parameters include spot diameter, shielding gas, powder carrier gas flow rate, etc., and adjusting cladding processing parameters include laser power, powder feeding, scanning speed, overlap rate, etc.;

[0011] Step (4) starts the cladding experiment. After setting the scanning path and method of cladding, it can be started directly without preheating the brake disc;

[0012] After step (5) cladding is completed, the laser is turned off, the cladding gun is controlled to move to a safe area, and the brake disc is allowed to cool naturally before sampling for subsequent analysis.

[0013] Preferably, the key element components of the iron-based alloy powder in step (1) are as follows (mass fraction): Cr (5-9%), Mo (1-2%), V (0.5-1%), W (0.03-0.06%), C (0.3-0.5%), and the balance is Fe.

[0014] Preferably, the powder in step (1) is dried at a temperature of 60° C. for 120 min, and is added to the powder feeder as soon as possible after being taken out of the oven.

[0015] Preferably, in step (2), the angle grinder is used to grind with a polishing disc until the surface is smooth, the surface is cleaned with anhydrous ethanol to remove oil stains, and the surface is carefully wiped dry with dust-free paper to ensure that the surface is dry.

[0016] Preferably, the fixed parameters in step (3) include setting the spot diameter to 4 mm, the protective gas to 14 L / min, the powder carrier gas flow rate to 5.5 L / min, and the cladding gun to a direction perpendicular to the substrate plane at an angle of 5° to avoid energy loss caused by laser reflection.

[0017] Preferably, in the step (3), the cladding processing parameters are as follows: the laser power is in the range of 1200-1600W, the powder feeding rate is in the range of 1.5-2.0r / min, and the scanning speed is in the range of 10-15mm / s; a stable single-pass coating can be prepared, the overlap rate is selected to be between 40-50%, a stable multi-pass overlapping coating can be prepared, and when the scanning line speed is 2-3m / min, a brake disc surface coating with very high surface quality can be prepared.

[0018] Preferably, the cladding scanning path in step (4) includes the following: when preparing a single-layer coating, the cladding direction and length are consistent; similarly, when multiple layers are overlapped, the direction of each cladding layer is consistent, which is a "Z"-shaped route, that is, rather than a reciprocating "S"-shaped route; when preparing a whole layer of coating on the brake disc, the path is to gradually overlap from the minimum radius interval of the cladding ring to the outer diameter.

[0019] Preferably, the cladding in step (4) does not require preheating in advance, and the cast iron material has good heat dissipation performance, especially when the laser power is in the range of 1200-1600W, the molten pool is stable.

[0020] Preferably, when the entire brake disc is prepared by the cladding processing route in step (4), the cladding route is overlapping from the smallest diameter to the largest diameter of the disc, so it is only necessary to determine the size of the brake disc.

[0021] Preferably, after the cladding in step (5) is completed, the sample is simply left to cool down naturally without the need for post-processing.

[0022] Beneficial effects: The method for preparing a wear-resistant iron-based alloy coating on the surface of an automobile brake disc by laser cladding of the present invention simplifies the cladding process, improves processing efficiency, and reduces processing costs, which is specifically manifested in the following aspects:

[0023] 1. The iron-based alloy powder selected in the present invention is low in price and has high friction performance compared to nickel-based alloy, carbide and other alloy powders;

[0024] 2. The present invention simplifies the cladding process and does not require sample preheating and heat treatment;

[0025] 3. The optimized process parameters of the present invention can form a coating sample with stable and well-formed performance on the surface of the brake disc. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the process flow for preparing a brake disc surface coating according to one embodiment of the present invention.

[0027] Figure 2Schematic diagram of the macroscopic structure and cross-sectional metallographic structure of a single-coat coating sample prepared in one embodiment of the present invention.

[0028] Figure 3 Schematic diagram of the microhardness curve and friction and wear curve of the cladding coating sample in one embodiment of the present invention.

[0029] Figure 4 This is a schematic diagram of a sample of a whole layer of coating on the surface of a brake disc in one embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following is a detailed description of an embodiment of the present invention in conjunction with the accompanying drawings: This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0031] like Figure 1 As shown, the present invention provides a method for preparing a laser-clad iron-based alloy wear-resistant coating on the surface of an automobile brake disc, comprising the following steps:

[0032] Step (1) Before cladding, the iron-based alloy powder was placed in a 60°C oven and dried for 120 minutes to ensure that the powder remained dry during the cladding process;

[0033] Step (2) Pretreatment of the substrate sample: Before cladding, use an angle grinder to grind the brake disc substrate to remove surface rust and oxide layers, while retaining a certain degree of surface roughness to avoid loss caused by laser energy reflection. Clean the surface with anhydrous ethanol and wipe it dry to keep it dry.

[0034] Step (3) setting cladding process parameters, fixed parameters include spot diameter (4 mm), shielding gas (14 L / min), powder carrier gas flow (5.5 L / min), etc., cladding processing parameters include laser power (1200-1600 W), powder feeding rate (1.5-2.0 r / min), scanning speed (10-15 mm / s), overlap rate (40-50%), and scanning line speed (2-3 m / min);

[0035] Step (4) Starting the cladding experiment can be started directly after setting the scanning path and mode of cladding, including single coating, multiple overlapping coatings and the entire brake disc;

[0036] After step (5) cladding is completed, the laser is turned off, the cladding gun is controlled to move to a safe area, and the brake disc is allowed to cool naturally before sampling for subsequent analysis.

[0037] Three specific embodiments are listed below:

[0038] Example 1

[0039] (1) Weigh 500 g of powdered raw material and place it in a 60°C oven for drying. After 120 minutes, add it to the powder feeder;

[0040] (2) Use an angle grinder to grind the brake disc base to remove the surface rust and oxide layer, and clean it with anhydrous ethanol and wipe it dry to ensure the surface is dry.

[0041] (3) Set the laser power to 1200W, the powder feeding rate to 1.5r / min, and the scanning speed to 10mm / s to prepare a single-pass coating. The sample morphology is as follows: Figure 2 shown.

[0042] (4) After the sample is cooled, perform wire cutting to observe the cross-section of the substrate and coating bonding area. The results are as follows: Figure 2 The cross-sectional morphology is shown.

[0043] Example 2

[0044] (1) Weigh 500 g of powdered raw material and place it in a 60°C oven for drying. After 120 minutes, add it to the powder feeder;

[0045] (2) Use an angle grinder to grind the brake disc base to remove the surface rust and oxide layer, and clean it with anhydrous ethanol and wipe it dry to ensure the surface is dry;

[0046] (3) Set the laser power to 1200 W, the powder feed rate to 1.5 r / min, the scanning speed to 10 mm / s, and the overlap rate to 50% to prepare multiple coatings;

[0047] (4) After the sample is cooled and wire cut, the microhardness curve and friction and wear properties of the coating are tested. The results are as follows: Figure 3 As shown in the results, the average microhardness of the surface coating can reach 800-900HV0.2, and the friction coefficient is stable at around 0.3.

[0048] Example 3

[0049] (1) Weigh 1500 g of powdered raw material and place it in a 60°C oven for drying. After 120 min, add it to the powder feeder;

[0050] (2) Use an angle grinder to grind the entire brake disc base to remove the surface rust and oxide layer, and clean it with anhydrous ethanol and wipe it dry to ensure the surface is dry;

[0051] (3) Set the laser power to 1200W, the powder feed rate to 2.0r / min, and the scanning speed to 2mm / s to prepare the entire brake disc coating;

[0052] (5) After the sample cools down, the actual picture is as follows Figure 4 shown.

[0053] Through the above embodiments, the present invention provides a method for preparing a laser-clad iron-based alloy wear-resistant coating on the surface of an automobile brake disc. The prepared coating sample has high performance, simple process and low powder cost.

[0054] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention.

[0055] The present invention may be modified and improved in various ways within the spirit and scope of the present invention.

[0056] The scope of protection of the present invention is determined by the appended claims.

[0057] Definition of claims and their equivalents.

Claims

1. A method for preparing a laser-clad iron-based alloy wear-resistant coating on the surface of an automobile brake disc, characterized in that: The steps include: Step (1) Before cladding, the iron-based alloy powder is placed in an oven for drying to ensure that the powder remains dry during the cladding process; Step (2) Pretreatment of the substrate sample: Before cladding, the brake disc substrate is first polished using an angle grinder to remove surface rust and oxide layers while retaining a certain degree of surface roughness to avoid loss caused by laser energy reflection; Step (3) setting cladding process parameters, fixed parameters including spot diameter, shielding gas, and powder carrier gas flow rate, and adjusting cladding processing parameters including laser power, powder feeding, scanning speed, and overlap rate; Step (4) starts the cladding experiment. After setting the scanning path and method of cladding, it can be started directly without preheating the brake disc; After step (5) cladding is completed, the laser is turned off, the cladding gun is controlled to move to a safe area, and the brake disc is allowed to cool naturally before sampling for subsequent analysis.

2. The method for preparing a laser-clad iron-based alloy wear-resistant coating on the surface of an automobile brake disc according to claim 1, characterized in that: The mass fractions of the elemental components of the iron-based alloy powder in step (1) are as follows: Cr: 5-9%, Mo: 1-2%, V: 0.5-1%, W: 0.03-0.06%, C: 0.3-0.5%, and the balance is Fe. The particle size of the iron-based alloy powder is 25-53 μm.

3. The method for preparing a laser-clad iron-based alloy wear-resistant coating on the surface of an automobile brake disc according to claim 1, characterized in that: The powder in step (1) is dried at a temperature of 60° C. for 120 min, and is added to the powder feeder as soon as possible after being taken out of the drying oven.

4. The method for preparing a laser-clad iron-based alloy wear-resistant coating on the surface of an automobile brake disc according to claim 1, characterized in that: In step (2), the angle grinder is used to grind with a polishing disc until the surface is smooth, the surface is cleaned with anhydrous ethanol to remove oil stains, and the surface is carefully wiped dry with dust-free paper to ensure that the surface is dry.

5. The method for preparing a laser-clad iron-based alloy wear-resistant coating on the surface of an automobile brake disc according to claim 1, characterized in that: The fixed parameters in step (3) include setting the spot diameter to 4 mm. If the spot is too large, the laser energy is not concentrated, resulting in energy waste, and if the spot is too small, it affects the processing efficiency; the protective atmosphere is selected from an inert gas such as argon, and the protective gas flow rate is set to 14 L / min; the powder-carrying atmosphere is also an inert gas such as argon, and the powder-carrying gas flow rate is set to 5.5 L / min. The powder feeding method is synchronous powder feeding, and the powder feeding port is an annular powder discharge; the cladding gun is at an angle of 5° with the direction perpendicular to the substrate plane to avoid energy loss caused by laser reflection.

6. The method for preparing a laser-clad iron-based alloy wear-resistant coating on the surface of an automobile brake disc according to claim 1, characterized in that: In the step (3), the cladding processing parameters are as follows: the laser power is in the range of 1200-1600W, the powder feeding rate is in the range of 1.5-2.0r / min, and the scanning speed is in the range of 10-15mm / s; a stable single-layer coating can be prepared, and the overlap rate is selected to be in the range of 40-50%. The surface of the multi-layer overlapped coating sample prepared in this range is smooth and highly uniform; When the scanning line speed is 2-3m / min, a brake disc surface coating with very high surface quality can be produced. When the scanning line speed is used to prepare the entire brake disc, the cladding moving speed is coupled with the speed of the brake disc turntable, and there is no need to adjust the turntable speed separately.

7. The method for preparing a laser-clad iron-based alloy wear-resistant coating on the surface of an automobile brake disc according to claim 1, characterized in that: The cladding scanning path in step (4) includes the following: when preparing a single-layer coating, the cladding direction and length are consistent; the same is true for multiple overlaps, and the direction of each cladding layer is consistent, which is a "Z"-shaped route, that is, not a reciprocating "S"-shaped route; when preparing a whole layer of brake disc coating, the path is to gradually overlap from the minimum radius interval of the cladding ring to the outer diameter.

8. The method for preparing a laser-clad iron-based alloy wear-resistant coating on the surface of an automobile brake disc according to claim 1, characterized in that: The cladding in step (4) does not require preheating in advance, and the cast iron material has good heat dissipation performance, especially when the laser power is in the range of 1200-1600W, the molten pool is stable.

9. The method for preparing a laser-clad iron-based alloy wear-resistant coating on the surface of an automobile brake disc according to claim 1, characterized in that: When the entire brake disc is prepared by the cladding processing route in step (4), the cladding route is to overlap from the smallest diameter to the largest diameter of the disc, so it is only necessary to determine the size of the brake disc.

10. The method for preparing a laser-clad iron-based alloy wear-resistant coating on the surface of an automobile brake disc according to claim 1, characterized in that: After the cladding is completed in step (5), the sample can be left to cool down naturally without any post-processing.

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