A high-performance laser cladding alloy tool

Abstract

The present invention discloses a high-performance laser cladding alloy tool, and the tool is provided with a laser cladding coating; the raw material powder system of the laser cladding coating is mainly prepared by mixing alloy powder, CeO2 powder with a weight percentage of 0.8% and rare earth La2O3 powder with a weight percentage of 0.6%. Through specific alloy powder, CeO2 powder with a weight percentage of 0.8%, rare earth La2O3 powder with a weight percentage of 0.6% and carbon nanotube reinforcement powder with a weight percentage of 1.2%, the present invention synergistically enhances the hardness and wear resistance of the laser cladding coating, so that the tool edge has a cutting edge with high hardness, high wear resistance, high corrosion resistance, and both strength and toughness.

Description

[0001] This application is a divisional application of the patent application with the patent number "202211158532.9", the application date of "20220922", and the title of "A High-performance Laser Cladding Alloy Tool and Its Preparation Method". Technical Field

[0002] The present invention belongs to the technical field of hardware knives and scissors, and specifically relates to a high-performance laser cladding alloy tool. Background Art

[0003] The wear resistance, strength and other properties of tools are key evaluation indicators for high-end kitchen knives. In traditional hardware knife and scissors technology, the methods for strengthening tools mainly include heat treatment, surface quenching, thermal diffusion technology, electroplating and thermal spraying, etc. Among them, heat treatment, surface quenching and thermal diffusion technology all change the performance of the blade without changing the matrix material, and the degree of improving the blade performance by these methods is very limited. Although electroplating and thermal spraying can form a coating layer with special alloy powder, the bonding strength between the coating layer and the matrix is limited.

[0004] With the demand for high-performance kitchen knives, foreign countries have combined laser cladding technology with the traditional hardware knife and scissors industry to develop laser cladding knives, which have also become the 'fifth-generation high-end tools'. However, through the research of the applicant, it is found that the existing laser cladding knives have the following technical problems:

[0005] The selection of alloy powder for the laser cladding coating is the main factor determining the service performance of the material. The current coatings mainly include self-fluxing alloy powder coatings, ceramic powder coatings, and ceramic-reinforced metal matrix composite coatings. Although the existing laser cladding coatings can better improve the hardness and wear resistance of tools, they still cannot well meet the performance requirements for high-end kitchen knives and also limit the specific applications of tools.

[0006] Therefore, there is still a need to develop a high-performance laser cladding alloy tool with high hardness and high wear resistance to meet the market demand. Summary of the Invention

[0007] The purpose of the present invention is to solve the above technical problems and provide a high-performance laser cladding alloy tool and its preparation method.

[0008] To solve the above problems, the present invention is realized according to the following technical solutions:

[0009] In the first aspect, the present invention provides a high-performance laser cladding alloy tool, and the tool is provided with a laser cladding coating;

[0010] The raw material powder system of the laser cladding coating is mainly prepared by mixing alloy powder, CeO2 powder with a weight percentage of 0.8% and rare earth La2O3 powder with a weight percentage of 0.6%.

[0011] In combination with the first aspect, the present invention also provides a first preferred embodiment of the first aspect. Specifically, the raw material powder system of the laser cladding coating is mainly prepared by mixing alloy powder, CeO2 powder at 0.8% by weight, rare earth La2O3 powder at 0.6% by weight, and carbon nanotube reinforcement powder at 1.2% by weight.

[0012] In combination with the first aspect, the present invention also provides a second preferred embodiment of the first aspect. Specifically, the raw material carbon nanotubes of the carbon nanotube reinforcement powder are provided with a titanium oxide coating layer.

[0013] In combination with the first aspect, the present invention also provides a third preferred embodiment of the first aspect. Specifically, the alloy powder includes the following components:

[0014] C: 0.46 wt%, Cr: 8 wt%, Ni: 3.2 wt%, Si: 2.4 wt%, B: 0.9 wt%, Mn: 0.32 wt%, Mo: 1.0 wt%, WC: 10 wt%, Cu: 3.2 wt%, Nb: 0.6 wt%, and the balance is Fe.

[0015] In combination with the first aspect, the present invention also provides a fourth preferred embodiment of the first aspect. Specifically, the cutting edge of the tool is a composite layer structure, and the cutting edge includes an intermediate layer and toughening layers on both sides of the intermediate layer;

[0016] The intermediate layer is made of 8Cr13MoV high-carbon and high-chromium material, and the toughening layer is low-carbon 1Cr13 stainless steel.

[0017] In the second aspect, the present invention also provides a preparation method for preparing a high-performance laser cladding alloy tool as described in the first aspect. The preparation method includes the following steps:

[0018] Step (1): Prepare each powder raw material of the laser cladding coating according to the above ratio, mix the powder raw materials evenly, and dry the mixed powder at a high temperature for 2 h to ensure the powder fluidity;

[0019] Step (2): Clean and dry the surface of the tool for standby, and pour the mixed powder into the powder feeder of the laser cladding system;

[0020] Step (3): Set the process parameters of the laser cladding system, and perform laser cladding on the tool to form a laser cladding coating on the tool.

[0021] In the third aspect, the present invention also provides a preparation method for preparing a high-performance laser cladding alloy tool as described in the first aspect. The preparation method includes the following steps:

[0022] Step (1): Prepare each powder raw material of the laser cladding coating according to the above ratio, mix the powder raw materials evenly, and dry the mixed powder at high temperature for 2 h to ensure the powder fluidity;

[0023] Step (2): Clean and dry the surface of the tool for standby, and lay the mixed powder on the surface of the tool;

[0024] Step (3): Set the process parameters of the laser cladding system, and perform laser cladding on the tool to form a laser cladding coating on the tool;

[0025] Among them, the laser cladding system is provided with an ultrasonic vibration assisting device, and the ultrasonic vibration assisting device is used to apply ultrasonic vibration to assist cladding during the laser cladding process of the tool.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] The present invention provides a high-performance laser cladding alloy tool, and the tool is provided with a laser cladding coating; the raw material powder system of the laser cladding coating is mainly prepared by mixing alloy powder, CeO2 powder with a weight percentage of 0.8%, and rare earth La2O3 powder with a weight percentage of 0.6%. The present invention uses specific alloy powder, CeO2 powder with a weight percentage of 0.8%, rare earth La2O3 powder with a weight percentage of 0.6%, and carbon nanotube reinforcing body powder with a weight percentage of 1.2% to synergistically enhance the hardness and wear resistance of the laser cladding coating, so that the tool edge has a cutting edge with high hardness, high wear resistance, high corrosion resistance, and both strength and toughness. Description of the Drawings

[0028] The following further describes in detail the specific embodiments of the present invention with reference to the drawings, where:

[0029] Figure 1 is the laser cladding system of the present invention provided with an ultrasonic vibration assisting device. Specific Embodiments

[0030] The following describes the preferred embodiments of the present invention with reference to the drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0031] At present, 304 stainless steel is widely used in household kitchen knives for production; 304 stainless steel is an austenitic stainless steel with excellent high-temperature resistance, corrosion resistance, sufficient toughness, low price, and good machinability. However, with the high demand for properties such as hardness and wear resistance in high-end kitchen knives, 304 stainless steel is difficult to meet the production application requirements of high-end kitchen knives. Therefore, by learning from the advanced foreign knife-making technology of laser cladding strengthening, a special performance material is cladded on the blade of ordinary knives as the blade, which can significantly improve the comprehensive performance of the blade and meet the requirements of foreign high-end knives. This will strongly promote the technological upgrading of China's kitchen knife industry and is an effective shortcut for China's kitchen knife industry to produce high-end kitchen knives and participate in the international high-end kitchen knife market competition.

[0032] The cladding material is the most basic factor affecting the comprehensive performance of the laser-cladded blade. Selecting a suitable and excellent-performance cladding material is the most basic condition for improving the blade performance. When selecting materials, they cannot be chosen randomly, otherwise, it cannot be ensured that the blade has corresponding excellent performance. Although the existing laser cladding coatings can better improve the hardness and wear resistance of the tool, they still cannot well meet the performance requirements of high-end kitchen knives and also limit the specific applications of the tool.

[0033] Therefore, the present invention provides a high-performance laser cladding alloy tool with high hardness and high wear resistance to meet the market demand.

[0034] Example 1 - The present invention provides a raw material powder system for a tool laser cladding coating

[0035] Example 1 of the present invention provides an alloy powder for a laser cladding coating applied to hardware knives and scissors, and a raw material powder system containing this alloy powder.

[0036] In the first preferred embodiment, the raw material powder system is mainly composed of alloy powder. The alloy powder includes the following components: C: 0.46wt%, Cr: 8wt%, Ni: 3.2wt%, Si: 2.4wt%, B: 0.9wt%, Mn: 0.32wt%, Mo: 1.0wt%, WC: 10wt%, Cu: 3.2wt%, Nb: 0.6wt%, and the balance is Fe.

[0037] In the second preferred embodiment, the raw material powder system is mainly prepared by mixing alloy powder, CeO2 powder at 0.8 wt% by weight, and rare earth La2O3 powder at 0.6 wt% by weight.

[0038] Among them, the alloy powder comprises the following components: C: 0.46 wt%, Cr: 8 wt%, Ni: 3.2 wt%, Si: 2.4 wt%, B: 0.9 wt%, Mn: 0.32 wt%, Mo: 1.0 wt%, WC: 10 wt%, Cu: 3.2 wt%, Nb: 0.6 wt%, and the balance is Fe.

[0039] In the 3rd preferred embodiment, the raw material powder system is mainly prepared by mixing alloy powder, CeO2 powder at 0.8 wt%, rare earth La2O3 powder at 0.6 wt%, and carbon nanotube reinforcement powder at 1.2 wt% by weight percentage.

[0040] Among them, the raw material carbon nanotubes of the carbon nanotube reinforcement powder are provided with a titanium oxide coating layer. The alloy powder comprises the following components: C: 0.46 wt%, Cr: 8 wt%, Ni: 3.2 wt%, Si: 2.4 wt%, B: 0.9 wt%, Mn: 0.32 wt%, Mo: 1.0 wt%, WC: 10 wt%, Cu: 3.2 wt%, Nb: 0.6 wt%, and the balance is Fe.

[0041] Among them, the powder particle size range is 100 - 300 mesh, that is, between 50 - 100 um.

[0042] In a specific implementation, the present invention forms a core - shell structure by coating a layer of titanium oxide on the surface of carbon nanotubes to reduce the direct ablation effect of carbon nanotubes.

[0043] The present invention also provides a preparation method of a high - performance laser - clad alloy tool, and the method comprises the following steps:

[0044] Step (1): Prepare each powder raw material of the laser - clad coating according to the above ratio, mix the powder raw materials evenly, and dry the mixed powder at a high temperature for 2 h to ensure the powder fluidity.

[0045] Among them, before laser cladding of the kitchen knife, the dryness of the powder will affect the stability of powder transportation and cause defects in the cladding layer. Therefore, before using the mixed powder, it needs to be dried, and the powder should not be oxidized due to too high temperature during the drying process. In view of this situation, the present invention uses a DZF - 6930 vacuum drying oven to ensure that the mixed powder is in a vacuum state, the drying temperature is 200 °C, the drying time is 2 hours, and after the powder drying is completed, the powder is added to the powder feeder for standby.

[0046] Step (2): Clean and dry the surface of the tool for standby, and pour the mixed powder into the powder feeder of the laser - clad system.

[0047] In a specific implementation, the pre-treatment of the tool further includes a tool preheating device. During the laser cladding process, there are many reasons for problems such as cracks, pores, and slag inclusions in the cladding layer. However, preheating is a very effective measure to help prevent defects in the cladding layer.

[0048] Step (3): Set the process parameters of the laser cladding system and perform laser cladding on the tool to form a laser cladding coating on the tool.

[0049] It should be noted that the process parameters (laser power, scanning speed, turntable speed, carrier gas volume, protective gas flow rate, etc.) can be reasonably set by those skilled in the art according to the hardware equipment and raw material powder system, and the process parameters can also be optimized through orthogonal experiments. Therefore, the present invention does not limit the process parameters.

[0050] On the other hand, the laser cladding system is an existing technology in the art. In this process, a coaxial powder feeding laser cladding processing working system specifically for tools is adopted, which mainly consists of a laser, an industrial robot, a cladding head, an air carrier powder feeder, a water cooling system, an automatic rotary workbench, a preheating system, and some external auxiliary equipment, etc.

[0051] The main core of the present invention is to provide a raw material powder system for a laser cladding coating. The hardware equipment of the laser cladding system is the existing hardware equipment in the art and can be configured by those skilled in the art according to needs. The present invention does not make excessive statements and descriptions about the hardware equipment.

[0052] I. Preparation Examples

[0053] Example 1

[0054] This Example 1 provides a high-performance laser cladding alloy tool, and a laser cladding coating is provided on the cutting edge of the tool; the raw material powder system of the laser cladding coating mainly consists of alloy powder. The alloy powder includes the following components: C: 0.46 wt%, Cr: 8 wt%, Ni: 3.2 wt%, Si: 2.4 wt%, B: 0.9 wt%, Mn: 0.32 wt%, Mo: 1.0 wt%, WC: 10 wt%, Cu: 3.2 wt%, Nb: 0.6 wt%, and the balance is Fe.

[0055] The preparation method of the high-performance laser cladding alloy tool described in this Example 1 includes the following steps:

[0056] Step (1): Prepare each powder raw material of the laser cladding coating according to the above ratio, mix the powder raw materials evenly, and dry the mixed powder at a high temperature for 2 h to ensure the powder fluidity.

[0057] Step (2): Clean and dry the surface of the tool for standby, and pour the mixed powder into the powder feeder of the laser cladding system.

[0058] Step (3): Set the process parameters of the laser cladding system (laser power 1400W, scanning speed 6mm / s, turntable speed 5r / min, carrier gas flow rate 5.4L / min, and protective gas flow rate 0.6 / Mpa), and perform laser cladding on the tool to form a laser cladding coating on the tool.

[0059] Example 2

[0060] This Example 2 provides a high-performance laser cladding alloy tool, and the cutting edge of the tool is provided with a laser cladding coating; the raw material powder system of the laser cladding coating is mainly prepared by mixing alloy powder, CeO2 powder at 0.8% by weight, and rare earth La2O3 powder at 0.6% by weight. The alloy powder includes the following components: C: 0.46wt%, Cr: 8wt%, Ni: 3.2wt%, Si: 2.4wt%, B: 0.9wt%, Mn: 0.32wt%, Mo: 1.0wt%, WC: 10wt%, Cu: 3.2wt%, Nb: 0.6wt%, and the balance is Fe.

[0061] The preparation method of the high-performance laser cladding alloy tool described in this Example 2 is exactly the same as that of Example 1, except for the process parameters of the laser cladding system: laser power 1600W, scanning speed 7mm / s, turntable speed 5r / min, carrier gas flow rate 6.4L / min, and protective gas flow rate 0.7 / Mpa.

[0062] Example 3

[0063] This Example 3 provides a high-performance laser cladding alloy tool, and the cutting edge of the tool is provided with a laser cladding coating; the raw material powder system of the laser cladding coating is mainly prepared by mixing alloy powder, CeO2 powder at 0.8% by weight, rare earth La2O3 powder at 0.6% by weight, and carbon nanotube reinforcement powder at 1.2% by weight. Among them, the raw material carbon nanotubes of the carbon nanotube reinforcement powder are provided with a titanium oxide coating. The alloy powder includes the following components: C: 0.46wt%, Cr: 8wt%, Ni: 3.2wt%, Si: 2.4wt%, B: 0.9wt%, Mn: 0.32wt%, Mo: 1.0wt%, WC: 10wt%, Cu: 3.2wt%, Nb: 0.6wt%, and the balance is Fe.

[0064] Among them, the raw material carbon nanotubes of the carbon nanotube reinforcement powder are provided with a titanium oxide coating layer, that is, a layer of titanium oxide is coated on the surface of the carbon nanotubes to form a core-shell structure. The purpose of such a design is to reduce the direct ablation damage of the laser to the carbon nanotubes. Titanium oxide-coated carbon nanotubes are existing materials in the art and can be prepared, for example, by the sol-reflux method.

[0065] The preparation method of the high-performance laser cladding alloy tool described in this Example 3 is exactly the same as that of Example 1, except for the process parameters of the laser cladding system: laser power 1800W, scanning speed 8mm / s, turntable speed 5r / min, carrier gas flow rate 6.4L / min, and protective gas flow rate 1.0 / Mpa.

[0066] Among them, the tools in the above Examples 1-3 use unground tool blanks, the material of which is 3Cr13 martensitic stainless steel, and the thickness of the tool blank is 2.5mm. The chemical composition of the tool material is shown in Table 1, and the mechanical properties are shown in Table 2.

[0067] Table 1 Chemical composition of 3Cr13 stainless steel (wt.%)

[0068] Grade C Si Mn P S Cr Ni Fe 3Cr13 0.28 0.80 0.70 0.024 0.025 13.4 0.50 Balance

[0069] Table 2 Mechanical properties of 3Cr13 stainless steel

[0070]

[0071]

[0072] II. Product performance testing

[0073] (I) Specimen preparation

[0074] After the tools in Examples 1-3 are completed with laser cladding, specimens with a size of 15×15mm are respectively intercepted along the cross-section of the cladding layer on the cutting edge of the tool by a wire cutting machine for microstructure analysis. First, grind the specimens with metallographic sandpapers of different models of 400#, 600#, 800#, 100#, 1200#, 1500#, and 2000#. Each time a new sandpaper is changed, the grinding marks of the previous sandpaper should be removed. Water cooling is required during grinding to ensure the original tissue state of the specimens; then, put the ground specimens on a polishing machine for polishing until all the grinding marks on the surface of the specimens are polished off; finally, rinse the polished specimens clean, corrode the tissues of the substrate and the cladding layer of the specimens with aqua regia, and rinse and dry them with alcohol.

[0075] (II) Analysis method of laser cladding coating

[0076] Phase composition analysis: The phase composition of the specimens is analyzed by a Rigaku Ultima IV X-ray diffractometer (XRD).

[0077] Macroscopic hardness test: The HR-150A Rockwell hardness tester was used to test the macroscopic hardness of the laser cladding coating. A load of 15 kg was used for the test, and 6-8 points were tested at any position, and the average value was taken.

[0078] Microhardness test: The HV-1000 microhardness tester was used to measure the microhardness of the laser cladding coating. A load of 0.2 kg was used for the actual measurement, and the loading time was 15 s. One point was tested every 0.2 mm from the top position of the cladding layer to the 3Cr13 stainless steel substrate.

[0079] Corrosion resistance test: An electrochemical workstation was used to characterize the corrosion resistance of the laser cladding coating.

[0080] Friction and wear performance test: The TRB multi-functional friction and wear testing machine was used to test the friction and wear performance of the laser cladding coating by means of a dry sliding friction test.

[0081] (3) Product performance analysis of Example 1

[0082] (1) Phase analysis of the laser cladding coating

[0083] The phase composition of the sample of Example 1 was analyzed, and it was found that the carbides formed by Fe, Cr, Ni, etc. in the alloy powder were mainly in the phases of M 23 C6, M7C3 (M is mainly Fe, Cr, and a small amount of W, Mo), and NiCx. Due to the presence of Nb element, MC-type carbide, i.e., NbC, was precipitated in the coating, and other phases such as α-Fe and ε-Cu were formed; the addition of WC generated WC phase and Fe3W3C hard phase.

[0084] It was found by SEM observation that most of the spherical WC particles were distributed near the interface between the laser cladding coating and the tool substrate. This is because the Marangoni effect in the molten pool affected the distribution of WC particles. Since the laser energy received at the top of the laser cladding coating was relatively high, the spherical WC particles were easily burned out, so there were fewer WC particles at the top of the cladding layer.

[0085] (2) Product performance

[0086] After testing, the microhardness of the laser cladding coating of Example 1 was 689.41 HV 0.2 , which was much higher than the microhardness of the 3Cr13 stainless steel substrate.

[0087] Analyzing the reasons, the microhardness depends on factors such as the microstructure type, grain size, and carbide size of the laser cladding coating. WC particles are added to the alloy powder of the present invention. The purpose is that these complete WC particles have a dispersion strengthening effect in the laser cladding coating. The WC particles are partially dissolved in the laser cladding coating, increasing the concentration of alloying elements around the WC particles. At the same time, the number of nucleation cores around increases, making the microstructure around the WC particles refined. The WC particles will aggregate in the laser cladding coating, thus promoting the refinement of grains. The Fe3W3C hard phase will further increase the strength and hardness of the laser cladding coating. There are unmelted WC particles in the cladding layer, and the distribution of the unmelted WC particles is uniform. Coupled with the diffusion of W elements in the laser cladding coating by the WC particles, it promotes the solid solution strengthening of the laser cladding coating, as well as the dispersion strengthening, hard phase strengthening, and fine grain strengthening of fine carbides, which results in excellent microhardness of the laser cladding coating. On the other hand, hard phases such as NbC, NiCx, and ε-Cu are generated in the coating, comprehensively improving the microhardness of the laser cladding coating.

[0088] After testing, the 3Cr13 stainless steel substrate fluctuates greatly during the entire running-in stage. As the friction time increases, it tends to be stable. The friction coefficient of the 3Cr13 stainless steel substrate is about 0.65. The friction coefficient of the laser cladding coating is relatively low, about 0.39551, and it fluctuates less during the entire running-in stage, showing excellent wear resistance.

[0089] The wear form of the coating of this technology is abrasive wear, and the wear resistance of the laser cladding coating is improved by the synergy of specific raw materials. On the one hand, the addition of Cr elements makes the γ phase in the cladding layer transform into the α phase. The α phase after the phase transformation is mainly composed of ferrite and martensite. Coupled with the strengthening effect of intermetallic compounds, the friction coefficient of the cladding layer decreases. On the other hand, the WC content of the present invention is 10%. The WC particles dispersed in the cladding layer are uniform, so the friction curve of the cladding layer fluctuates less. The addition of WC will improve the plasticity and toughness of the cladding layer. During the wear test, the abrasive grains will push the material to both sides through reciprocating motion, resulting in a large plastic deformation. Under the continuous action of the abrasive grains, the material accumulated in the wear scar will be flattened again, and repeated plastic deformation may occur, which results in a strengthening effect on the surface of the cladding layer. And when the high-hardness reinforcing phase WC is added to the cladding layer, these reinforcing phases will reduce the indentation depth of the abrasive grains during the wear process. Therefore, the wear resistance of the laser cladding coating is improved.

[0090] After testing, the self-corrosion potential of the coating is -0.8825V, the pitting potential is -160±5mV, and the passivation potential is -854±5. The wide passivation zone of the present invention indicates strong passivation ability of the laser cladding coating. It is easy to generate a passivation film, and the passivation rate is fast, so as to improve the passivation ability of the coating surface and enhance the corrosion resistance of the cladding layer. Analyzing the reasons for the above phenomena, since Ni and Fe elements are active elements in aqueous solution and Cr is a passivating element, with the addition of Cr, it is easy to form a passivation film, which can effectively inhibit the intrusion of the electrolyte into the cladding layer, reduce its dissolution rate, and enhance the corrosion resistance of the cladding layer.

[0091] (4) Product performance analysis of Example 2

[0092] (1) Phase analysis of laser cladding coating

[0093] The phase composition of the sample of Example 2 was analyzed. New phases LaNi3 and trace amounts of La2O3 appeared in the XRD pattern, and the other main phases had little difference from those of Example 1. It shows that excessive La2O3 does not participate in chemical reactions and will exist in the cladding layer in the form of stable inclusions. Due to the small content of CeO2, it has no significant effect on the phases of the laser cladding coating.

[0094] (2) Product performance

[0095] Through the morphological analysis of Example 2, the surface of the coating is flat, without defects such as cracks and pores. No cracks and pores are found between the coating and the tool, and the metallurgical bonding performance between the coating and the tool is excellent.

[0096] Pores are prone to be the initiation points of cracks during the cladding process. By regulating the auxiliary laser cladding with rare earth elements, the porosity can be reduced. The addition of rare earth oxides enhances the fluidity of the molten pool, promotes the escape of gas inside the molten pool, and plays a role in degassing.

[0097] After testing, the microhardness of the laser cladding coating of Example 2 is 701.25HV 0.2 , and the microhardness has increased. This is because rare earth has the functions of purifying and refining the microstructure. At the same time, rare earth and rare earth compounds are also a kind of hard phase existing in the coating, thus increasing the hardness of the cladding layer. However, the amount of rare earth should not be excessive. Excessive rare earth itself is an inclusion, and at the same time reduces the fluidity of the molten pool and the uneven distribution of the microstructure, so it will reduce the hardness of the cladding layer. On the other hand, the Ce atoms generated after the decomposition of CeO2 will diffuse and segregate at grain boundaries, dislocations, etc., to reduce the Gibbs free energy of the system, thereby weakening the driving force for grain growth, and then refining the microstructure of the cladding layer. The finer the grains, the more grain boundaries per unit volume, and the more significant the hindering effect of grain boundaries on dislocations, the higher the hardness.

[0098] After testing, it was found that the friction coefficient of the laser cladding coating of Example 2 increased slightly to about 0.41242 due to the addition of rare earth oxides.

[0099] The samples of Example 1 and Example 2 were selected for three-point bending test, and their load-displacement data were tested. The linear stage of Example 1 terminated at a displacement of 0.424mm, and the load at this time was 2.864kN, and plastic deformation occurred immediately until the peak load was 6.279kN, and damage occurred. The displacement when damage occurred was 2.026mm. The linear stage of the cladding layer of Example 2 terminated at a displacement of 0.532mm, and the load at this time was 3.687kN, and plastic deformation occurred immediately. Destruction and fracture occurred at a peak load of 6.845kN, and the corresponding maximum displacement was 2.088mm. According to the sample parameters and the bending strength formula, it can be calculated that the bending strength of Example 1 is quite different from that of Example 2. Compared with Example 1, the laser cladding coating of Example 2 has better toughness, can absorb a certain amount of external stress when subjected to external load, and has higher bending strength load-displacement data.

[0100] For the existing laser cladding knives, after sharpening, the cutting parts of the blade are all laser cladding coatings, such as Example 1. Although Example 1 has high hardness and high wear resistance, it also leads to greater brittleness. The strengthened blade is easy to break and damage the performance of the blade, which will limit the application scenarios, such as being only suitable for fruit knives and slicing knives. To this end, the present invention adds 0.8% by weight of CeO2 powder and 0.6% by weight of rare earth La2O3 powder to make the tool have a cutting blade with high hardness, high wear resistance, high corrosion resistance, strength and toughness. This is because the addition of CeO2 and La2O3 rare earth oxides is conducive to the nucleation of the organizational structure of the cladding layer, and the obtained organization is also more refined and uniform. After the grains of the cladding layer are refined, while improving the strength and hardness of the cladding layer, the plasticity and toughness of the cladding layer metal are also enhanced.

[0101] (V) Product performance analysis of Example 3

[0102] (1) Phase analysis of laser cladding coating

[0103] The phase composition analysis of the sample of Example 3 shows no significant difference from that of Example 2. Through SEM observation, it is found that the carbon nanotube reinforcement with core-shell structure is distributed in the laser cladding coating. This is because the laser first acts on the titanium oxide coating on the outer wall of the carbon nanotube, preventing the carbon nanotube from being burned by the high-energy laser, so that the carbon nanotube structure can be fully retained in the coating.

[0104] (2) Product performance

[0105] After testing, the microhardness of the laser cladding coating of Example 3 is 720.85HV 0.2, the microhardness has been improved. This is due to the addition of carbon nanotube reinforcements coated with titanium oxide. Their specific strength and specific stiffness are extremely high, which can improve the ability of the composite to resist deformation. Moreover, under the protection of titanium oxide, more carbon nanotube reinforcements are completely retained in the laser cladding coating, which has a strong effect on the matrix structure of the laser cladding coating, increasing the grain boundary area and enhancing the microhardness of the laser cladding coating.

[0106] After testing, due to the addition of carbon nanotube reinforcements coated with titanium oxide, the friction coefficient of the laser cladding coating in Example 3 is slightly reduced, about 0.398152. This is because the high lubricity of the carbon nanotube reinforcements coated with titanium oxide can effectively reduce the friction coefficient of the coating. It can be seen that carbon nanotubes not only enhance the hardness of the coating but also play a role in solving the negative effect of the increase in friction coefficient caused by the addition of rare earth CeO2 and La2O3.

[0107] The present invention uses specific alloy powder, CeO2 powder with a weight percentage of 0.8%, rare earth La2O3 powder with a weight percentage of 0.6%, and carbon nanotube reinforcement powder with a weight percentage of 1.2% to synergistically enhance the hardness and wear resistance of the laser cladding coating, making the cutting edge of the tool have high hardness, high wear resistance, high corrosion resistance, and a cutting edge with both strength and toughness.

[0108] Example 2 - The present invention provides a method for preparing a laser cladding coating for a tool

[0109] For the high-performance laser cladding alloy tool described in this Example 2, the raw material powder system of the laser cladding coating of the tool is exactly the same as that of Example 1. The difference is that the present invention provides a new method for preparing a laser cladding coating for a tool. Specifically, the method for preparing the laser cladding coating for the tool includes the following steps:

[0110] Step (1): Prepare each powder raw material of the laser cladding coating according to the above ratio, mix the powder raw materials evenly, and dry the mixed powder at a high temperature for 2 h to ensure the powder fluidity.

[0111] Among them, before laser cladding of the kitchen knife, the dryness of the powder will affect the stability of powder delivery and cause defects in the cladding layer. Therefore, before using the mixed powder, it needs to be dried, and the powder cannot be oxidized due to too high temperature during the drying process. In view of this situation, the present invention uses a DZF-6930 vacuum drying oven to ensure that the mixed powder is in a vacuum state, the drying temperature is 200 °C, the drying time is 2 hours, and after the powder drying is completed, the powder is added to the powder feeder for use.

[0112] Step (2): Clean and dry the surface of the tool for standby, and lay the mixed powder on the surface of the tool.

[0113] In a specific implementation, the pre-treatment of the tool further includes a tool preheating device. During the laser cladding process, there are many reasons for problems such as cracks, pores, and slag inclusions in the cladding layer. However, preheating is a very effective measure to help prevent defects in the cladding layer.

[0114] In the present invention, Example 2 uses the pre-placed powder method, also known as the manual powder laying method, which refers to laying the cladding material powder system on the surface of the tool substrate material to be cladded before the experiment by hand or using a gravity device.

[0115] Step (3): Set the process parameters of the laser cladding system and perform laser cladding on the tool to form a laser cladding coating on the tool;

[0116] Among them, the laser cladding system is provided with an ultrasonic vibration assisting device, and the ultrasonic vibration assisting device is used to apply ultrasonic vibration to assist cladding during the laser cladding process of the tool.

[0117] As Figure 1 , shown, the laser cladding system is a prior art in the art. In this process, a laser cladding processing working system specifically for tools is used, which mainly consists of a laser, a cladding head, a water cooling system, a workbench, a preheating system, and some external auxiliary devices, etc.

[0118] Among them, the process parameters can be reasonably set by those skilled in the art according to the hardware equipment and the raw material powder system, and the process parameters can also be optimized through orthogonal experiments. Therefore, the present invention does not limit the process parameters. In Example 2 of the present invention, the parameters are set as the laser power is 1400W, the scanning speed is 5mm / s, the spot diameter is 4mm, etc. Ultrasonic vibration is applied synchronously to the laser cladding coating, the frequency is 20KHz, the application angle is 45°, and the power is 350W. In order to prevent the coating from being oxidized at high temperature, nitrogen with a volume fraction of 99.9% is used as the protective gas during the experiment, and the gas flow rate is 15L / min.

[0119] In Example 4, the raw material powder system formula of Example 3 is selected. The raw material powder system is mainly prepared by mixing alloy powder, CeO2 powder with a weight percentage of 0.8%, rare earth La2O3 powder with a weight percentage of 0.6%, and carbon nanotube reinforcement powder with a weight percentage of 1.2%. Among them, the raw material carbon nanotubes of the carbon nanotube reinforcement powder are provided with a titanium oxide coating layer. The alloy powder includes the following components: C: 0.46wt%, Cr: 8wt%, Ni: 3.2wt%, Si: 2.4wt%, B: 0.9wt%, Mn: 0.32wt%, Mo: 1.0wt%, WC: 10wt%, Cu: 3.2wt%, Nb: 0.6wt%, and the balance is Fe. The tool is prepared by the above process.

[0120] For the specimen of Example 4, it was found that when the ultrasonic power was 350 W, the microhardness of the laser cladding coating reached 783.18 HV 0.2 . This is because the cavitation effect and acoustic streaming agitation generated by ultrasonic waves can refine the coating structure, reduce the grain size, increase the number of crystal nuclei, and play a role in grain refinement strengthening. The yield strength of the material increases with the decrease of the grain diameter. Therefore, grain refinement is beneficial to improving the hardness of the coating and the mechanical properties are excellent.

[0121] Example 3 - The present invention provides a tool body of a high-performance laser cladding alloy tool

[0122] The raw material powder system and process of this Example 3 are exactly the same as those of Example 1. The difference is that the cutting edge of the tool is a composite layer structure, and the raw material powder system is cladded on the cutting edge of the composite layer structure.

[0123] Among them, the cutting edge includes an intermediate layer and toughening layers located on both sides of the intermediate layer; the intermediate layer is made of 8Cr13MoV high-carbon high-chromium material, and the toughening layer is low-carbon 1Cr13 stainless steel. The cutting edge is made by compounding different performance materials. The center is a high-hardness wear-resistant layer, and the two sides are relatively soft toughening layers. The number of composite layers can also be 5 layers, etc. according to different functional requirements.

[0124] The relatively thin intermediate layer is made of 8Cr13MoV high-carbon high-chromium material with excellent performance. This metal has characteristics such as high hardness and wear resistance after heat treatment, while the side material is low-carbon 1Cr13 stainless steel with general performance, which can protect and improve the toughness of the cutting edge. This three-layer cutting edge is combined into an integral body by explosion welding.

[0125] After laser cladding treatment, three regions, namely the cladding zone, the transition zone, and the substrate (composite cutting edge), are formed on the cross-section. The cladding layer and the substrate are well combined, and the internal structure of the cladding layer is dense, without defects such as cracks, pores, and inclusions. This is attributed to the adopted raw material powder system. The cladding layer and the surface of the composite cutting edge penetrate and fuse with each other, enabling the transition zone to obtain good metallurgical bonding.

[0126] Through this design, in cooperation with rare earth elements, the cutting edge of the laser cladding tool is given excellent toughness.

[0127] For other structures of the high-performance laser cladding alloy tool and its preparation method described in this example, refer to the prior art.

[0128] The above is only a preferred embodiment of the present invention, and does not impose any form of limitation on the present invention. Therefore, any modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A high-performance laser cladding alloy tool, characterized in that, The tool is provided with a laser cladding coating; The raw material powder system of the laser cladding coating is prepared by mixing alloy powder, CeO2 powder at 0.8% by weight, rare earth La2O3 powder at 0.6% by weight, and carbon nanotube reinforcement powder at 1.2% by weight; The alloy powder includes the following components: C: 0.46wt%, Cr: 8wt%, Ni: 3.2wt%, Si: 2.4wt%, B: 0.9wt%, Mn: 0.32wt%, Mo: 1.0wt%, WC: 10wt%, Cu: 3.2wt%, Nb: 0.6wt%, and the balance is Fe; Among them, the particle size range of each powder is 100 - 300 mesh; The cutting edge of the tool is a composite layer structure, and the raw material powder system of the laser cladding coating is cladded on the cutting edge; The cutting edge includes an intermediate layer and toughening layers on both sides of the intermediate layer. The intermediate layer and the toughening layers are combined into an integral body by explosive welding; the intermediate layer is made of 8Cr13MoV high-carbon and high-chromium material, and the toughening layer is low-carbon 1Cr13 stainless steel.

2. A high-performance laser cladding alloy tool according to claim 1, wherein: The raw material carbon nanotubes of the carbon nanotube reinforcement powder are provided with a titanium oxide coating layer.

3. The preparation method of a high-performance laser cladding alloy tool according to claim 2, characterized in that, The preparation method includes the following steps: Step (1): Prepare each powder raw material of the laser cladding coating according to the above ratio, mix each powder raw material evenly, and dry the mixed powder at high temperature for 2h to ensure the powder fluidity; Step (2): Clean and dry the surface of the tool for standby, and pour the mixed powder into the powder feeder of the laser cladding system; Step (3): Set the process parameters of the laser cladding system, and perform laser cladding on the tool to form a laser cladding coating on the tool.

4. The preparation method of a high-performance laser cladding alloy tool according to claim 2, characterized in that, The preparation method includes the following steps: Step (1): Prepare each powder raw material of the laser cladding coating according to the above ratio, mix each powder raw material evenly, and dry the mixed powder at high temperature for 2h to ensure the powder fluidity; Step (2): Clean and dry the surface of the tool for standby, and lay the mixed powder on the surface of the tool; Step (3): Set the process parameters of the laser cladding system, and perform laser cladding on the tool to form a laser cladding coating on the tool; Among them, the laser cladding system is provided with an ultrasonic vibration assisting device, and the ultrasonic vibration assisting device is used to apply ultrasonic vibration assistance during the laser cladding process of the tool.

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