Preparation process of copper surface laser cladding Cu-TiB2 coating

Abstract

The invention relates to the technical field of laser cladding, in particular to a copper surface laser cladding Cu-TiB2 coating preparation process which comprises cladding powder, a base material and irradiation of laser equipment for cladding, the power of the laser equipment is 5500 W, the scanning speed is 25 mm / s or 35 mm / s, the light spot diameter is 4.5 mm, a Cu-TiB2 laser cladding layer is obtained, the cladding powder is 5wt% of TiB2 and 95wt% of Cu powder, and the laser equipment is used for cladding. The process comprises the following specific process steps that S1, firstly, 800 #, 400 # and 80 # abrasive paper is adopted for polishing the surface of a base material, and after ultrasonic cleaning is conducted for 5 min, drying is conducted for standby application; s2, mixing 5wt% of TiB2 and 95wt% of Cu powder with PVA colloid diluted by water to form paste, manually coating the surface of a base material with the paste, and controlling the thickness of a preset layer to be 1mm; according to the preparation process of the copper surface laser cladding Cu-TiB2 coating, the surface of a copper alloy is coated with 5 wt% of TiB2 and 95 wt% of Cu powder, and a cladding layer obtained by adopting the laser power of 5000 W and the scanning rate of 35 mm / s or 25 mm / s is compact in structure, free of cracks and other defects and good in metallurgical bonding with a base material at the extreme temperature.

Description

Technical Field

[0001] The invention relates to the technical field of laser cladding, and in particular to a process for preparing a copper surface laser cladding Cu-TiB2 coating. Background Art

[0002] Laser cladding is a surface modification technology that adds cladding material to the surface of the substrate and uses a laser beam to melt it together with the substrate.

[0003] Existing electromagnetic railgun rails mostly use CuCrZr alloy. The present invention uses QAL9-4 aluminum bronze alloy as the base material and clads Cu-5wt% TiB2 metal powder on its surface to improve the strength of the electromagnetic railgun rail. Compared with CuCrZr alloy rail materials, the hardness, wear resistance and ablation resistance are all improved, achieving the goal of low cost and lightweight electromagnetic railgun. Summary of the Invention

[0004] The present invention aims to provide a process for preparing a Cu-TiB2 coating by laser cladding on a copper surface to address the failure issues of existing electromagnetic railgun rails mentioned in the background art. The process utilizes a QAL9-4 aluminum bronze alloy as a substrate, upon which Cu-5wt% TiB2 metal powder is clad on its surface to enhance the strength of the electromagnetic railgun rail. Compared to conventional electromagnetic railgun CuCrZr alloys, the process exhibits improvements in hardness, wear resistance, and thermal shock resistance, thereby achieving low-cost and lightweight electromagnetic railguns. To achieve the aforementioned objectives, the present invention provides the following technical solutions: a process for preparing a Cu-TiB2 coating by laser cladding on a copper surface, comprising cladding powder, a substrate, and irradiation with a laser device for cladding at a power of 5500W, a scanning speed of 25mm / s or 35mm / s, and a spot diameter of 4.5mm. The resulting Cu-TiB2 laser cladding layer comprises a cladding powder composed of 5wt% TiB2 and 95wt% Cu powder. The specific process steps are as follows:

[0005] S1: First, use 800#, 400# and 80# sandpaper to polish the substrate surface, and then use ultrasonic cleaning for 5 minutes and dry it for later use;

[0006] S2: 5wt% TiB2-95wt% Cu powder was mixed with water-diluted PVA colloid to form a paste, which was then coated on the substrate surface with a pre-deposited layer thickness of 1mm. The pre-deposited sample was placed in a dryer for drying at 60°C for 6 hours.

[0007] S3: The laser power was set to 5500W, the scanning speed was set to 25mm / s or 35mm / s, the spot diameter was 4.5mm, the overlap rate of the laser multi-pass cladding was 30%, and coaxial argon gas was used for local protection with an argon gas flow rate of 15L / min;

[0008] S4: Laser irradiation is applied to the surface of the substrate, and a Cu-TiB2 coating is obtained after cooling.

[0009] The 5wt% TiB2-95wt% Cu powder has an average particle size of 75μm Cu and 5μm TiB2, wherein the purity of Cu and TiB2 are both ≥99.9%.

[0010] The laser equipment adopts a YAG laser with a wavelength of 900-1100nm and a maximum power of 6kW, and the laser adopts a VB106 laser head.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] In the present invention, the cladding layer obtained by coating 5wt% TiB2-95wt% Cu powder on the surface of the copper alloy and using a laser power of 5000W and a scanning rate of 35mm / s or 25mm / s has a dense structure under extreme temperature conditions, is free of defects such as cracks, and has good metallurgical bonding with the substrate.

[0013] In the present invention, the cladding layer obtained by coating 5wt% TiB2-95wt% Cu powder on the surface of the copper alloy and using a laser power of 5000W and a scanning rate of 35mm / s or 25mm / s has a hardness far greater than that of the substrate and slightly higher than that of the CuCrZr alloy. The hardness of the cladding layer prepared at 35mm / s is slightly higher than that of the cladding layer prepared at 25mm / s, and high hardness is proportional to high wear resistance, so the cladding layer prepared at 35mm / s and the cladding layer prepared at 25mm / s both have excellent wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a flowchart of the process of the present invention;

[0015] Figure 2 Graph showing the distribution of microhardness of the A1 cladding layer and the A2 cladding layer versus coating depth in Example 5 of the present invention;

[0016] Figure 3 This is a histogram of the surface hardness of the substrate, CuCrZr alloy, A1 cladding layer, and A2 cladding layer in Example 5 of the present invention;

[0017] Figure 4 This is a friction coefficient curve of the substrate, CuCrZr alloy, A1 cladding layer and A2 cladding layer at 257°C in Example 5 of the present invention;

[0018] Figure 5 This is a histogram of the wear rates of the substrate, CuCrZr alloy, A1 cladding layer, and A2 cladding layer at 257°C in Example 5 of the present invention;

[0019] Figure 6 This is a histogram of the wear scar width and depth of the substrate, CuCrZr alloy, A1 cladding layer, and A2 cladding layer at 257°C in Example 5 of the present invention;

[0020] Figure 7 This is a SEM image of the wear scar morphology of the substrate, CuCrZr alloy, A1 cladding layer and A2 cladding layer at 257°C in Example 5 of the present invention;

[0021] Figure 8 XRD diffraction patterns of the ablated surfaces of the substrate, CuCrZr alloy, A1 cladding layer, and A2 cladding layer in Example 5 of the present invention;

[0022] Figure 9 Ablation rates of the substrate, CuCrZr alloy, A1 cladding layer and A2 cladding layer according to the embodiment of the present invention;

[0023] Figure 10 Surface morphologies of the substrate, CuCrZr alloy, A1 cladding layer, and A2 cladding layer after thermal shock at 250° C. in Example 5 of the present invention;

[0024] Figure 11 Schematic diagram of the structure of the substrate, CuCrZr alloy, A1 cladding layer and A2 cladding layer in Example 5 of the present invention after thermal shock at 900°C;

[0025] Figure 12 This is a graph showing the hardness variation of the Cu / TiB2 composite material with different TiB2 contents in Example 1 of the present invention;

[0026] Figure 13 Graph showing the electrical conductivity of Cu / TiB2 composite materials with different TiB2 contents in Example 1 of the present invention;

[0027] Figure 14 This is a table showing specific implementation parameters for multi-pass cladding at different laser powers in Example 2 of the present invention;

[0028] Figure 15 Detailed implementation parameter diagram of multi-pass melting at different laser powers in Example 2 of the present invention;

[0029] Figure 16 This is a macroscopic morphology diagram of multi-pass melting under different laser powers in Example 2 of the present invention;

[0030] Figure 17 This is a cross-sectional morphology diagram of the laser cladding layer at different laser powers in Example 2 of the present invention;

[0031] Figure 18Graph showing the relationship between characteristic dimensions of the cladding layer and laser power in Example 2 of the present invention (v=5 mm / s);

[0032] Figure 19 This is a table showing the parameters for the cladding layer of the third embodiment of the present invention, using cladding powder (5wt% TiB2-95wt% Cu) and laser power (5000W) at different scanning speeds;

[0033] Figure 20 This is a macroscopic morphology diagram of a single-pass cladding process in Example 3 of the present invention;

[0034] Figure 21 The cross-sectional morphology of the cladding layer at different laser scanning speeds in Example 3 of the present invention;

[0035] Figure 22 Graph showing the relationship between the characteristic size of the cladding layer and the laser scanning speed in Example 3 of the present invention (P=800W);

[0036] Figure 23 Parameter table diagram of Example 4 of the present invention at laser scanning speeds of 25 mm / s and 35 mm / s;

[0037] Figure 24 This is a cross-sectional view of the A1 cladding layer in Example 4 of the present invention;

[0038] Figure 25 This is a longitudinal cross-sectional view of the A1 cladding layer in the fourth embodiment of the present invention;

[0039] Figure 26 This is a cross-sectional view of the A2 cladding layer in the fourth embodiment of the present invention;

[0040] Figure 27 This is a laser confocal three-dimensional morphology reconstruction image of Example 4 of the present invention at 257°C. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0042] Example 1

[0043] Using SPS technology, the cladding powder was divided into four powders with TiB2 contents of 0wt.%, 1wt.%, 5wt.%, and 10wt.%. The blocks with different TiB2 contents were analyzed for morphology, organization, and phase, and their performance was tested. Then, the optimal composition (5wt.% TiB2) was selected from these three compositions and further composition design was carried out around it (4wt.%, 5wt.%, 6wt.%). The friction coefficient, wear rate, and conductivity were also tested.

[0044] Depend on Figure 12 The wear rates and Figure 13 The electrical conductivity of Cu / TiB2 composites with different TiB2 contents is shown. It can be seen that 5wt.% TiB2 has excellent hardness, friction and wear properties and electrical conductivity.

[0045] Example 2

[0046] According to the optimal (5wt% TiB2-95wt% Cu) cladding powder parameters obtained in Example 1, multiple passes of cladding were performed at different laser powers; the specific implementation parameters and morphology are as follows: Figure 14 、 Figure 15 and Figure 16 As shown, Figure 17 Middle: (a) 4500W (b) 4750W (c) 5000W (d) 5250W (e) 5500W. The figure shows that when the laser power is 4500W and 5250W, some macro defects such as holes can be observed inside the cladding layer. When the laser power reaches 5500W, the quality of the cladding layer is significantly reduced. Too high laser power will lead to excessive energy density, thereby increasing the cladding dilution rate, causing excessive introduction of substrate elements into the cladding layer, affecting its wear resistance and corrosion resistance, and may even cause overburning and evaporation of the cladding material. When the laser power is too low, the energy density is low, the cladding material cannot be fully melted, resulting in a low dilution rate of the cladding layer, which in turn affects the bonding strength between the cladding layer and the substrate, affecting its appearance and forming quality.

[0047] In order to more comprehensively characterize the morphological characteristics of the cross-section of the cladding layer, this example conducted a statistical analysis of the melt height H, melt depth h, melt width W, dilution rate η, and aspect ratio K. The dilution rate η can be calculated using the following formula. The contact angle θ of the cladding layer will change with changes in the laser process parameters, and this change can be evaluated by the aspect ratio K. The contact angle θ is the shape factor of the cladding layer, and its change reflects the combined influence of multiple factors such as laser process parameters and cladding materials on the shape of the cladding layer. The calculation formula for the aspect ratio K is:

[0048]

[0049] At the same time, the relationship between aspect ratio and contact angle can be obtained:

[0050]

[0051] From the above formula, it can be seen that θ is a single function of K. θ is generally 90 to 180° and decreases with the increase of K value.

[0052] Figure 18 Figure 3. (a) Variation of melt width, melt height, melt depth and dilution rate with laser power (b) Relationship between aspect ratio and laser power. It shows the relationship between the characteristic size of the cladding layer and laser power. With the increase of laser power, the melt width and melt depth of the cladding layer gradually increase, while the melt height gradually decreases. When the laser power reaches 5500W, the melt width reaches the maximum value. With the increase of laser power, the aspect ratio shows a decreasing trend and is relatively large at 4500W. The effect is optimal at 5000W.

[0053] Example 3

[0054] The optimal cladding powder parameters (5wt% TiB2-95wt% Cu) and the optimal laser power (5000W) at different scanning speeds are obtained from the above examples 1 and 2. The implementation parameters and morphology are as follows: Figure 19 and Figure 20 As shown, Figure 21 Medium, (a) 15mm / s (b) 20mm / s (c) 25mm / s (d) 30mm / s (e) 35mm / s;

[0055] Figure 22 (a) Variation of melt width, melt height, melt depth and dilution rate with laser scanning speed (b) Relationship between aspect ratio and laser scanning speed;

[0056] Depend on Figure 19 、 Figure 20 、 Figure 21 and Figure 22 It was found that the best results were achieved at laser scanning speeds of 25 mm / s and 35 mm / s.

[0057] Example 4

[0058] According to the first, second and third embodiments, it is known that the laser cladding layer has good forming quality under the conditions of laser power 5000W, laser scanning speed 25mm / s and 35mm / s, spot diameter 4.5mm, cladding powder thickness 1mm and overlap rate 30%. The microstructure of the cladding layer under the conditions of 25mm / s and 35mm / s is analyzed. The parameters are as follows: Figure 23 As shown (A1 is the cladding layer obtained at 25 mm / s; A2 is the cladding layer obtained at 35 mm / s);

[0059] Figure 24 In the figure, (b), (c), (d) and (e) are partial enlarged views of (a);

[0060] Figure 25 (b), (c) and (d) are partial enlarged views of (a);

[0061] By observing the microstructure morphology of the bottom, middle, top and overlapping areas of the cross-section of the cladding layer A1, it can be seen that the cladding layer and the substrate have formed a good metallurgical bond. There is a clear interface between the substrate-heat-affected zone-cladding layer. The cross-section of the cladding layer is relatively smooth, and no defects such as cracks are observed inside, indicating that the cladding layer is well formed. The structure at the bottom of the cladding layer is mainly planar crystals and long columnar crystals. Through the cross-section of the A1 cladding layer (Figure b), it can be found that the structure gradually away from the cladding layer interface is long columnar crystals, and equiaxed crystals can be observed at the top of the cladding layer.

[0062] The formation of microstructure after the molten pool cools is mainly affected by the temperature gradient (G) and the solidification rate (R). During the laser cladding process, due to the large heat input of the laser beam, the alloy powder will melt into a molten pool on the substrate surface. Since the temperature rises and falls very rapidly during the laser cladding process, when the laser beam leaves the molten pool, the molten metal will solidify quickly. During laser cladding, the microstructure near the substrate receives the least heat radiation, so the temperature is the lowest and solidifies first. The part closer to the molten pool has a gradually higher temperature, which makes it difficult to cool down, takes longer time, and has the smallest degree of supercooling.

[0063] Therefore, when the laser beam works, the metal near the substrate surface is still in a molten state when the surface of the cladding layer begins to solidify, resulting in a very large temperature gradient at the bottom of the cladding layer, that is, a large G / R value. Therefore, the crystals grow in the bonding area between the substrate and the cladding layer in the form of planar crystals, and some columnar crystals appear. After the planar crystals are formed, the solidification interface continues to advance into the molten pool. The released latent heat of crystallization causes the substrate temperature to rise. At this time, the interface temperature gradient decreases, the G / R value also begins to decrease, and columnar crystals begin to form. Due to the rapid heating and cooling characteristics of the laser, the growth direction of the columnar crystals at the bottom of the cladding layer is perpendicular to the bottom and upward or slightly inclined. This is mainly because the heat dissipation perpendicular to the bottom is the fastest, and the heat flow direction leads to selective growth. As the crystallization process proceeds, the temperature gradient continues to decrease, and the crystal structure of the cladding layer continues to transform into columnar crystals and equiaxed crystals.

[0064] Figure 26 In the figure, (b), (c), (d) and (e) are partial enlarged views of (a);

[0065] After the A2 cladding layer was corroded, it was found that each coarse columnar crystal was composed of fine subgrains. In the cross-sectional view (b) of the A2 cladding layer, equiaxed subgrains were observed on one side of the top of the cladding layer, and elongated honeycomb subgrains were observed inside the large columnar crystals on the other side. The cross-sectional image shown in the cross-sectional view (a) of the A2 cladding layer shows the heat-affected zone formed by the secondary heat input of the next laser energy to the previously solidified cladding layer. It is worth noting that the solidified part on the right side of the heat-affected zone shows a transition from fine columnar subgrains to elongated cellular subgrains to ultrafine equiaxed subgrains from bottom to top, while the molten zone on the left side of the heat-affected zone is composed of elongated cellular subgrains growing perpendicular to the lap line.

[0066] Example 5

[0067] The comparison and analysis of the current guide rail material Cu-Cr-Zr by using the A1 cladding layer and the A2 cladding layer in Example 3 and Example 4 are as follows:

[0068] Depend on Figure 2 and Figure 3 It can be seen that the surface hardness of the A1 cladding layer and the A2 cladding layer is better than that of the current CuCrZr alloy;

[0069] During the electromagnetic rail launch process, high-speed relative motion occurs between the hub and rail interfaces, causing wear. At the same time, under the action of Joule heat and frictional heat, the rail surface temperature rises, causing the material to soften, further reducing the contact performance between the projectile and the rail. Existing research has calculated through simulation that the surface temperature of the copper rail after a single launch is 257°C. Therefore, the friction and wear performance of the copper alloy substrate and the Cu-5wt% TiB2 coating were tested at a temperature of 257°C.

[0070] Depend on Figure 4 It can be seen that the friction coefficients of the four materials all increase slowly in the stable wear stage, indicating that high temperature affects the wear resistance of the materials. The substrate enters the stable wear stage after a very rapid running-in stage. In contrast, the Cu-Cr-Zr alloy experiences a longer running-in stage. The friction and wear curves of the A1 cladding layer and the A2 cladding layer are relatively similar. After a shorter running-in stage, they remain in a stable range until the end of the friction test. In general, the A1 cladding layer and the A2 cladding layer still have a lower friction coefficient at 257°C, and have better stability than the substrate.

[0071] Depend on Figure 5 It can be seen that when the ambient temperature rises from room temperature to 530K, the wear rate of the substrate increases by 30.41%, while that of the copper-chromium-zirconium alloy increases by 16.93%, and the wear rates of the A1 and A2 cladding layers only increase by 15.65% and 13.16%, respectively. This indicates that the addition of TiB2 particles can effectively improve the wear resistance of the material in high temperature environments.

[0072] Figure 27 Among them, (a) matrix material (b) Cu-Cr-Zr (c) A1; (d) A2;

[0073] Combined diagram Figure 27 (Laser confocal 3D topography reconstruction at 257°C) and Figure 6 It can be seen that the substrate has the largest wear scar width and wear scar depth, and the A2 cladding layer has the smallest wear scar width and depth, which shows that the laser cladding coating at a temperature of 257°C can also greatly improve the wear resistance of the substrate;

[0074] Depend on Figure 7 It can be seen that the wear scar morphology of the four cladding layers is mainly plowing and layered peeling, and some debris and protrusions appear on the surface of the substrate. At high temperature, an oxide film is easily formed on the surface of the substrate, and the oxide film may peel off during the friction process, resulting in oxidative wear. Under high temperature environment, the plasticity of aluminum bronze alloy increases, so more plastic wear may occur, resulting in surface deformation and peeling. A large amount of peeling occurs on the surface of Cu-Cr-Zr coating. Copper-chromium-zirconium alloy has good oxidation resistance. The oxide layer may be stable at high temperature, but it may also be damaged by friction, resulting in oxidative wear. The surfaces of A1 and A2 cladding layers are relatively smooth, and micro-plowing and a small amount of peeling are observed. At high temperature, the surfaces of A1 and A2 coatings may oxidize to form oxide films. These oxides will peel off during the friction process, causing oxidative wear. As the temperature increases, the strengthening effect of TiB2 particles may decrease, resulting in particle shedding, thereby inducing abrasive wear. Therefore, at high temperature, the A1 and A2 cladding layers mainly exhibit oxidative wear, adhesive wear, and abrasive wear.

[0075] Depend on Figure 9It can be seen that the ablation rate of A1 and A2 cladding layers is lower, and their ablation resistance is significantly better than that of the substrate and the current guide rail material Cu-Cr-Zr alloy. Although the substrate contains aluminum, which can improve its corrosion resistance and form an aluminum oxide film at high temperature to hinder ablation, the aluminum oxide film may crack or peel off at higher temperatures or in complex environments, and its thermal conductivity and heat resistance are lower than those of the other two materials. Therefore, it performs the worst during the ablation process. The oxides of chromium and zirconium in copper-chromium-zirconium alloy are highly stable, which can more effectively prevent oxygen from contacting the alloy matrix and slow down the ablation process. The addition of chromium and zirconium to copper-chromium-zirconium alloy improves the strength and heat resistance of the alloy. The chromium element can improve the wear resistance of the alloy, while the zirconium element helps to enhance the toughness of the material. This is obviously equivalent to the good high temperature resistance and oxidation resistance of the substrate copper-chromium-zirconium alloy. / TiB2 coating combines the excellent thermal conductivity of copper with the high melting point and excellent thermal stability of TiB2. The presence of TiB2 can significantly improve the high temperature resistance and oxidation resistance of the coating. The high melting point and chemical stability of TiB2 make the coating less susceptible to damage in high temperature environments and can effectively resist the erosion of ablative media. At the same time, it can be seen that the ablation performance of A2 is slightly higher than that of A1. The fine grain structure can improve the thermal conductivity of the material and help to evenly distribute heat, thereby reducing the risk of local overheating and improving the ablation performance. In addition, more grain boundaries provide more reaction interfaces, making it easier for certain alloys to form a protective oxide film in an oxidizing environment, thereby reducing further ablation. The fine grain structure usually has a larger surface area, which can effectively resist the erosion of the ablative medium and slow the expansion of local damage.

[0076] Thermal shock tests are used to apply thermal stress to the copper alloy surface cladding layer to simulate the working environment of the guide rail surface, thereby indirectly verifying whether the cladding layer can meet actual application requirements;

[0077] Depend on Figure 10 It can be seen that after 200 thermal shocks, the surface morphology of the coating only showed oxidation, and no cracking or falling off occurred. This shows that the prepared Cu / TiB2 coating material has excellent thermal stability and can maintain structural integrity under rapid temperature changes, effectively resisting the influence of thermal stress. The strong bonding force between the coating and the substrate ensures that no peeling or falling off occurs during the thermal shock process, indicating that the interface between them is well adhered. In addition, the thermal expansion coefficients between the coating and the substrate are well matched, avoiding stress accumulation caused by inconsistent thermal expansion.

[0078] from Figure 11It can be seen that even after 200 times of thermal shock at 900 degrees, the A1 cladding layer and the A2 cladding layer still did not show cracks, bulging, and falling off, indicating that the A1 and A2 cladding layers formed a good metallurgical bond with the substrate. The thermal expansion coefficient of Cu is about 16.5×10-6 / K (between 20℃ and 200℃). The thermal expansion coefficient of copper is relatively large, which is a typical value for metal materials. It will increase with increasing temperature at high temperatures. The thermal expansion coefficient of TiB2 is about 8.1×10-6 / K (between room temperature and 1000℃). TiB2 is a ceramic material with a low thermal expansion coefficient and small changes, and has high thermal stability. The thermal expansion coefficients of Cu and TiB2 are The difference is large (Cu is about twice that of TiB2), but in the cladding layer, the reinforcement effect of TiB2 particles can significantly suppress the overall thermal expansion non-uniformity and slow down the concentration of thermal stress. This performance is particularly important during thermal shock, because the high elastic modulus and strength of TiB2 can effectively buffer the stress accumulation inside the coating, thereby improving the overall thermal shock resistance. At the same time, the added TiB2 content is 5wt% TiB2. Adding a low content of TiB2 can reduce the difference in the thermal expansion coefficient of the overall coating, thereby reducing the thermal stress caused by thermal shock. The appropriate TiB2 content can achieve thermal expansion matching between the coating and the substrate, reducing the thermal stress accumulation during thermal shock.

[0079] In summary, the copper alloy coating did not crack or fall off after thermal shock, demonstrating its superior performance under extreme temperature conditions and is suitable for application scenarios requiring high durability and stability.

[0080] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for preparing a Cu-TiB2 coating by laser cladding on a copper surface, characterized in that: The Cu-TiB2 laser cladding layer is obtained by irradiating a laser device with a power of 5500W, a scanning speed of 25mm / s or 35mm / s, and a spot diameter of 4.5mm. The cladding powder is 5wt% TiB2-95wt% Cu powder. The specific process steps are as follows: S1: First, use 800#, 400# and 80# sandpaper to polish the substrate surface, and then use ultrasonic cleaning for 5 minutes and dry it for later use; S2: 5wt% TiB2-95wt% Cu powder was mixed with water-diluted PVA colloid to form a paste, which was then coated on the substrate surface with a pre-deposited layer thickness of 1mm. The pre-deposited sample was placed in a dryer for drying at 60°C for 6 hours. S3: The laser power was set to 5500W, the scanning speed was set to 25mm / s or 35mm / s, the spot diameter was 4.5mm, the overlap rate of the laser multi-pass cladding was 30%, and coaxial argon gas was used for local protection with an argon gas flow rate of 15L / min; S4: Laser irradiation is applied to the surface of the substrate, and a Cu-TiB2 coating is obtained after cooling.

2. The process for preparing a Cu-TiB2 coating by laser cladding on a copper surface according to claim 1, characterized in that: The 5wt% TiB2-95wt% Cu powder has an average particle size of 75μm Cu and 5μm TiB2, wherein the purity of Cu and TiB2 are both ≥99.9%.

3. The process for preparing a Cu-TiB2 coating by laser cladding on a copper surface according to claim 1, wherein: The substrate is QAL9-4 aluminum bronze alloy, which includes 88.3% Cu, 9.061% Al, 2.464% Fe, 0.07% Ca, 0.066% K, 0.033% Ni, 0.022% Mn and 0.013% Ge.

4. The process for preparing a Cu-TiB2 coating by laser cladding on a copper surface according to claim 1, wherein: The laser equipment adopts a YAG laser with a wavelength of 900-1100nm and a maximum power of 6kW, and the laser adopts a VB106 laser head.

Images