Ceramic toughening powder material for laser cladding and preparation method thereof

Abstract

The invention belongs to the technical field of metal-based composite materials and surface engineering, and relates to a ceramic toughening powder material for laser cladding and a preparation method of the ceramic toughening powder material. The powder material comprises the following components in percentage by weight: 62%-65% of Ni, 16%-20% of Cr, 6%-8% of Al, 3%-5% of Ta, 2%-3% of Hf, 0.1%-0.5% of Y, 0.03%-0.07% of C, 1%-5% of YSZ and 3%-6% of TiO2. The powder material disclosed by the invention is used for a high-performance protective coating for laser cladding, and the coating is suitable for strengthening the surface of a component at a high temperature of 800-1200 DEG C in a corrosion environment containing sulfur and chlorine; the interface diffusion phenomenon of the coating prepared from the powder material is weakened; the corrosion resistance and the wear resistance are both achieved; the dosage of YSZ is reduced by 60-80%, the material cost is reduced by 25%, and high performance / cost ratio optimization is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal matrix composites and surface engineering, and relates to a ceramic toughening laser cladding powder material and a preparation method thereof. BACKGROUND

[0002] Under high temperature and strong corrosion conditions, the surface of equipment components is prone to corrosion damage such as oxidation, sulfidation and chlorination, accompanied by wear problems, which seriously affects the service life and reliability of the equipment. Traditional surface treatment technologies, such as electroplating and thermal spraying, have defects such as low coating bonding strength, insufficient high-temperature resistance and limited corrosion resistance. Laser cladding technology has become a research hotspot in the field of surface protection because it can achieve metallurgical bonding between the coating and the substrate and accurately control the composition and performance of the coating. However, existing laser cladding powder materials often contain a high content of small-atomic-radius elements such as C and B in order to maintain high hardness, and there is still room for improvement in terms of inhibiting small-atomic diffusion, resisting sulfur-chlorine combined corrosion and improving wear resistance, which makes it difficult to meet the long-term use requirements under extreme conditions. Therefore, it is of great significance to develop a high-performance composite powder suitable for laser cladding for improving the surface performance of components.

[0003] Existing high-temperature corrosion protection materials face two major contradictions: ① the addition of high-hardness ceramic phases (such as YSZ) leads to thermal expansion mismatch cracks; ② reducing the content of ceramic phases reduces cracks, but the wear resistance and corrosion resistance decrease. Traditional solutions usually sacrifice one performance to optimize the other, making it difficult to achieve a balance of comprehensive performance. SUMMARY

[0004] To solve the problems in the prior art, the application provides a nickel-based ceramic reinforced metal composite powder toughened by uniform distribution of YSZ and TiO2, and a high-performance protective coating preparation method based on laser cladding, which is suitable for surface strengthening of components under high temperature (800-1200℃) and sulfur-chlorine corrosion environment. Through innovative component design and process optimization, the application realizes the uniform distribution of YSZ and TiO2 in the coating and synergistically improves the comprehensive performance of the material.

[0005] To achieve the above-mentioned application purposes, the application provides the following technical solutions:

[0006] A ceramic toughening laser cladding powder material, the composition comprises, by weight percentage: Ni: 62-65%; Cr: 16-20%; Al: 6-8%; Ta: 3-5%; Hf: 2-3%; Y: 0.1-0.5%; C: 0.03-0.07%; YSZ: 1-5%; TiO2: 3-6%.

[0007] Preferably, the weight ratio of YSZ to TiO2 is 1:(2-4).

[0008] Preferably, the particle size of the YSZ is 50-100 nm.

[0009] Preferably, the TiO2 is rutile particles with a particle size of 1-5 μm.

[0010] The Ni matrix provides excellent toughness and high-temperature stability, and its face-centered cubic structure reduces the diffusion coefficient of elements. Cr forms a Cr2O3 oxide film on the material surface, improving oxidation resistance and simultaneously strengthening the matrix through solid solution. Al and Cr work synergistically to form an Al2O3 oxide film, enhancing the density of the oxide film and reducing the risk of penetration by corrosive media such as sulfur and chlorine. Ta has a large atomic radius, which inhibits grain boundary diffusion, forming a highly stable Ta2O5 oxide that effectively resists sulfur corrosion. The Hf-formed HfO2 is dense. The oxide film can improve the adhesion of the oxide film, while the HfC hard phase enhances the wear resistance of the material; Y, as a rare earth element, can improve the continuity of the oxide film and inhibit the peeling of the oxide film; TiO2 (1-5μm) ceramic particles play a dispersion strengthening role in the coating in the micron state, among which YSZ (Y2O3 stabilized ZrO2) ceramic particles are dispersed in the TiO2 surface in the nanoscale (50-100nm), and the different deformations of the two different ceramic materials under thermal expansion and stress can achieve complementary toughness strengthening of the two ceramic particles.

[0011] The specific steps of the preparation method of the above-mentioned powder material for laser cladding of toughened ceramics are as follows:

[0012] Raw material pretreatment and mixing: YSZ and TiO2 are dry-mixed in a high-energy ball mill at a ratio of 1:(2-4) for 2 hours. Mechanical force is used to uniformly disperse nano-YSZ among TiO2 (1-5μm) particles, forming nano-YSZ-toughened TiO2 ceramic particles. Ni powder, Cr powder, Al powder, Ta powder, Hf powder, Y powder, and nano-YSZ-toughened TiO2 ceramic particles with a purity ≥99.5% are weighed according to a set weight percentage. The weighed metal powder and TiO2 ceramic particles are then placed together in a high-energy ball mill for ball milling. Mechanical force ensures thorough and uniform mixing of all components, obtaining a mixed raw material. During mixing, the evaporation of anhydrous ethanol prevents powder agglomeration, ensuring good dispersibility of the mixed raw material. Preferably, the ball milling conditions are: anhydrous ethanol as the milling medium, a ball-to-material ratio of 8:1, a ball mill speed of 300 r / min, and a mixing time of 12-15 hours.

[0013] Melting process: The mixed raw materials are transferred to a vacuum induction melting furnace for heating and melting. Preferably, the vacuum level is below 10. -3Under the condition of Pa, the mixture is heated and melted at a rate of 10-15℃ / min, raising the temperature to 1650-1700℃, so that the mixed raw materials are completely melted into a uniform alloy liquid, ensuring that each element is fully dissolved and evenly distributed.

[0014] Atomization powder production: The alloy liquid is converted into powder by gas atomization or water atomization.

[0015] Gas atomization: The molten alloy liquid is guided to the atomizing nozzle through a guide tube. High-pressure inert gas (such as argon, with a pressure of 3-5 MPa) is injected at high speed from multiple directions to impact the alloy liquid flow, breaking it into fine droplets. The droplets rapidly cool and solidify during flight to form powder. During gas atomization, by adjusting the gas pressure, nozzle structure, and injection angle, the powder particle size is preferably controlled between 45-106 μm, while ensuring that the powder has good sphericity and flowability.

[0016] Water atomization: After the molten alloy is guided to the atomization zone, it is impacted and broken up by a high-pressure water flow (15-25 MPa) to form fine droplets. These droplets rapidly cool and solidify into powder in the water. Powder prepared by water atomization cools faster and has a finer grain structure, but its sphericity is slightly worse than that of powder prepared by air atomization. Similarly, by adjusting the water pressure and nozzle parameters, the powder particle size can be made to meet the requirement of 45-106 μm.

[0017] Powder post-treatment: The powder obtained by atomization is sieved to remove powder particles that do not meet the requirements in terms of particle size; then it is dried, preferably at a temperature of 80-100℃ for 2-4 hours, to remove the moisture adsorbed on the powder surface and obtain the final nickel-based ceramic reinforced metal composite powder.

[0018] Synergistic effect mechanism of uniform distribution of YSZ and TiO2

[0019] 1. Theory of Synergistic Regulation of Thermal Stress

[0020] Precise phase transformation toughening of YSZ: Nanoscale YSZ (Y2O3 stabilized ZrO2, 50-100nm) maintains its tetragonal phase at high temperatures. When the coating is subjected to tensile stress, the tetragonal phase → monoclinic phase transformation produces a 4% volume expansion, consuming crack propagation energy and increasing fracture toughness to 9-11 MPa·m. 1 / 2 Its coefficient of thermal expansion is 10.5 × 10⁻⁶. -6 / ℃) and Ni matrix (13.3×10 -6 A moderate temperature difference ( / ℃) generates approximately 100 MPa of compressive stress, inhibiting the initiation of microcracks. The uniformly distributed YSZ particles in the coating act as stress dispersion centers, effectively suppressing crack propagation at various locations.

[0021] Compressive stress strengthening of TiO2: Rutile TiO2 (thermal expansion coefficient 8.6 × 10⁻⁶) -6 ( / ℃) forms a 4.7×10 with the Ni matrix. -6 The expansion difference of / ℃ generates a compressive stress of 150-200MPa throughout the coating area. The uniformly distributed TiO2 particles ensure that the compressive stress is applied evenly throughout the coating, further enhancing its crack resistance. Together, these factors achieve comprehensive control over thermal stress.

[0022] 2. Synergistic enhancement of corrosion resistance

[0023] Uniform protection of the composite oxide film: The uniformly distributed YSZ forms a chemically inert barrier, blocking Cl. - Permeation path; TiO2 reacts with Cr2O3 to form a TiO2–Cr2O3 solid solution, whose lattice constant With Cr2O3 The high degree of matching results in a composite passivation layer with a 30% increase in density. This composite oxide film provides uniform coverage across the entire coating surface, reducing the corrosion depth to 3.2-3.5 μm in a 5% SO2 atmosphere (compared to 4 μm for conventional Cr2O3 films).

[0024] Interfacial energy regulation inhibits sulfide formation: Hf elements form an HfO2 transition layer (50-80 nm thick) at the YSZ-TiO2 interface, reducing the interfacial energy from 0.5 J / m2 to 0.3 J / m2, hindering S diffusion into the matrix, and improving the effectiveness of Ta2O5 in resisting sulfur by 20%. The uniform distribution of YSZ and TiO2 ensures that this interfacial energy regulation effect is uniformly exerted within the coating, effectively inhibiting sulfide formation.

[0025] 3. Complementary reinforcement mechanism of wear resistance

[0026] Synergistic effect of dual hard phases: Uniformly dispersed YSZ (HV1200-1500) enhances the hardness of the matrix through dispersion strengthening, while TiO2 and HfC form a composite hard phase (HV1300-1500). Under abrasive impact, these uniformly distributed hard phases generate dislocation interactions, which significantly reduces the wear volume.

[0027] Plastic deformation coordination mechanism: When the TiO2 content is controlled at 3-6%, the thermal mismatch stress between TiO2 and the Ni matrix can promote micro-plastic deformation of the matrix and absorb abrasive impact energy. Because TiO2 is uniformly distributed in the coating, this plastic deformation coordination effect can also be uniformly manifested, extending the wear resistance life by 15% compared to a single YSZ coating.

[0028] Preparation process ensures uniformity

[0029] 1. Uniform mixing technology for powder preparation

[0030] Two-step mixing method: Step 1: YSZ and TiO2 are dry-mixed in a high-energy ball mill at a ratio of 1:2 for 2 hours. Mechanical force is used to uniformly disperse nano-YSZ (50nm) between TiO2 (0.6-5μm) particles. Step 2: Metal powder is added and wet-mixed for 12 hours (anhydrous ethanol medium, ball-to-powder ratio 8:1). The molecular-level uniform dispersion of ceramic phase and metal powder is achieved through surface hydroxyl bonding, ensuring that YSZ and TiO2 are uniformly distributed in the powder and solving the problem of agglomeration of low-content YSZ.

[0031] Precise control of melting temperature: The vacuum induction melting temperature is set at 1650-1700℃. At this temperature, TiO2 and Ni matrix undergo slight interdiffusion (diffusion depth 10-20nm), while YSZ can also be uniformly dispersed in the alloy liquid to form a uniform composite system, ensuring the uniformity of the final powder composition.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The interfacial diffusion phenomenon is weakened by reducing the content of C elements or carbides and reducing the content of B, thereby reducing interfacial diffusion. At the same time, carbon fixation is achieved by using Ta, which further reduces the interfacial diffusion.

[0034] (2) It has both anti-corrosion and anti-wear properties. It uses elements such as Al, Cr, and Ta to form an oxide film, and uses Hf and Y to improve the adhesion of the oxide film and improve the anti-sulfur corrosion performance. HfC is also generated in the coating and together with ceramic additives to improve the erosion wear resistance.

[0035] (3) Balance between cost and performance: YSZ usage is reduced by 60-80%, material cost is reduced by 25%, and high performance / cost ratio is optimized. Attached Figure Description

[0036] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0037] In the attached diagram:

[0038] Figure 1 This is a schematic diagram of the metallographic structure of the atomized powder. Detailed Implementation

[0039] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer with the description. However, the embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0040] Example 1

[0041] This implementation case uses a nickel-based alloy system reinforced with nano-ceramic particles. The specific composition and proportions are as follows:

[0042] Nickel-based alloy powder: by mass percentage, it contains Cr: 17.3%, Al: 7.8%, Ta: 4.0%, Hf: 2.5%, Y: 0.5%, C: 0.04%. The balance is Ni and unavoidable impurities.

[0043] Nano-ceramic particles: 0.6-3μm TiO2 ceramic particles and 50nm YSZ nano-ceramic particles are selected.

[0044] Powder preparation: YSZ and TiO2 were dry-mixed in a high-energy ball mill at a ratio of 1:2 for 2 hours. Mechanical force was used to uniformly disperse nano-YSZ (50nm) among TiO2 (1-5μm) particles, forming nano-YSZ-toughened TiO2 ceramic particles (NYTO). 99% by weight of the above-mentioned nickel-based alloy and 1% by weight of the nano-YSZ-toughened TiO2 ceramic particles (NYTO) were weighed according to the set weight percentages. The weighed metal powder and TiO2 ceramic particles were placed together in a high-energy ball mill, using anhydrous ethanol as the milling medium. The ball-to-material ratio was controlled at 8:1, the ball mill speed was set to 300 r / min, and the mixing time was 12 hours. Mechanical force was used to ensure thorough and uniform mixing of the components, obtaining a mixed raw material. During the mixing process, the evaporation of anhydrous ethanol prevented powder agglomeration, ensuring good dispersibility of the mixed raw material.

[0045] Melting process: The mixed raw materials are transferred to a vacuum induction melting furnace, where the vacuum level is below 10. -3 The mixture is heated and melted under the condition of Pa. The heating rate is controlled at 10-15℃ / min, and the temperature is raised to 1650℃ to completely melt the mixed raw materials into a uniform alloy liquid, ensuring that each element is fully dissolved and evenly distributed.

[0046] Gas atomization powder production: Using a gas atomization device, the molten alloy is converted into powder. The molten alloy is guided to the atomizing nozzle through a guide tube, and 5MPa argon gas is injected at high speed from multiple directions to impact the alloy flow, breaking it into fine droplets. These droplets rapidly cool and solidify during flight to form powder. During gas atomization, the powder particle size is controlled between 45-106μm by adjusting the gas pressure, nozzle structure, and injection angle, while ensuring good sphericity and flowability of the powder.

[0047] Powder post-treatment: The powder obtained by atomization is sieved to remove powder particles that do not meet the requirements; then it is dried at 80-100℃ for 2-4 hours to remove the moisture adsorbed on the powder surface, and the final nickel-based ceramic reinforced metal composite powder is obtained.

[0048] Coating preparation process and performance testing: On a stainless steel substrate, pulsed laser cladding was performed (frequency 20Hz, duty cycle 60%) with a laser power of 2000W and a scanning speed of 8mm / s. Powder was fed using a coaxial powder feeder. The resulting coating thickness was 1.2mm. No cracks or pores were generated during the cladding process. The coating was dense. Figure 1 This is a schematic diagram of the metallographic structure of a coating made from atomized powder.

[0049] For corrosion resistance testing, the samples were placed in a H2-1% H2S corrosive medium and subjected to hydrogen sulfide corrosion at 700℃. The corrosion time was 100 hours. Samples were removed and weighed at each time point, and the corrosion condition of the coating surface was observed and recorded. Finally, the corrosion kinetic curve was plotted based on the coating weight gain at each corrosion time point. After 100 minutes of corrosion testing, the corrosion layer depth on the surface of the composite material sample was only 4.52 μm, lower than the 10.78 μm corrosion depth of laser-clad 625 alloy.

[0050] Wear resistance testing procedure: A pin-disc friction and wear testing machine was used. The composite material was processed into cylindrical pins with a diameter of 6 mm and a height of 10 mm as the test specimens. The grinding material was a 45# steel disc. The test was conducted under dry friction conditions with a load of 50 N, a rotation speed of 200 r / min, and a wear time of 60 min. The wear rate was calculated by measuring the mass loss of the specimen before and after wear. After 60 min of wear test, the mass loss of the composite material specimen was 0.02 g, and the calculated wear rate was 2.0 × 10⁻⁶ g. -5 mm / N·m, lower than 7.8×10 mm / N·m for alloy 625 under the same test conditions. -4 mm / N·m wear rate.

[0051] Example 2

[0052] 3% by weight of nano-YSZ-toughened TiO2 ceramic particles (NYTO) were added to the composite powder, with the remainder remaining the same as in Example 1. The resulting coating, under the same test conditions as in Example 1, exhibited a corrosion depth of 4.33 μm and a wear rate of 1.7 × 10⁻⁶. -5 mm / N·m, with better wear resistance.

[0053] Example 3

[0054] In the composite process of nano-YSZ toughened TiO2 ceramic particles, 50-nanometer YSZ was used to composite with TiO2 ceramic particles (NYTO) at a weight ratio of 1:4. After forming NYTO powder, the rest was the same as in Example 1. The coating corrosion depth was 4.34 micrometers, and the wear rate was 1.76 × 10⁻⁶. -5 mm / N·m.

[0055] Comparative Example 1

[0056] 7% by weight of nano-YSZ toughened TiO2 ceramic particles (NYTO) were added to the composite powder, while the rest remained the same as in Example 1. Under the same test conditions as in Example 1, the resulting coating was prone to cracking during the cladding process and ceramic particle segregation occurred.

[0057] Comparative Example 2

[0058] Nano-YSZ toughened TiO2 ceramic particles (NYTO) were added to the composite powder at a weight ratio of 0.5%, while the rest remained the same as in Example 1. The resulting coating, under the same test conditions as in Example 1, exhibited a corrosion depth of 4.73 μm and a wear rate of 5.4 × 10⁻⁶. -4 mm / N·m, the wear resistance becomes worse.

[0059] Comparative Example 3

[0060] In the process of composite of nano-YSZ toughened TiO2 ceramic particles, 50 nanometer YSZ is used to composite with TiO2 ceramic particles (NYTO) at a weight ratio of 1:5. After forming NYTO powder, the rest is the same as in Example 1. Cracking is prone to occur during the cladding process or during the service of the coating.

[0061] Comparative Example 4

[0062] The content of Ta in the nickel-based alloy is 2%, and the rest is the same as in Example 1. During the long-term high-temperature service of the coating, the effect of Ta on carbon fixation is weakened, and some C migration will still occur at the interface, causing interfacial catalysis. At the same time, the formation of Ta2O5 is reduced, which weakens the coating's resistance to sulfur corrosion.

[0063] Comparative Example 5

[0064] The nickel-based alloy contains 1% Hf, and the rest is the same as in Example 1. During long-term high-temperature service, the adhesion of the dense oxide film formed on the coating surface weakens, making it prone to cracking and damage during thermal shock, leading to accelerated corrosion.

[0065] Comparative Example 6

[0066] The Hf content in the nickel-based alloy is 0.2%, and the rest is the same as in Example 1. During long-term high-temperature service, the adhesion of the dense oxide film formed on the coating surface weakens, making it prone to cracking and damage during thermal shock, leading to accelerated corrosion.

[0067] Comparative Example 7

[0068] The contents of Ta, Hf, and Y in the nickel-based alloy exceed the values ​​specified in this invention, while the rest are the same as in Example 1, which leads to increased material costs and reduced economic benefits.

[0069] Comparative Example 8

[0070] In the composite process of nano-YSZ toughened TiO2 ceramic particles, 30-nanometer YSZ toughened TiO2 ceramic particles (NYTO) are used, and the rest is the same as in Example 1. The nano-YSZ particles are difficult to disperse and are prone to agglomeration, which can easily cause cracks during the cladding process.

[0071] Comparative Example 9

[0072] In the process of composite material of nano-YSZ toughened TiO2 ceramic particles, 150 nano-YSZ toughened TiO2 ceramic particles (NYTO) are used. However, it is difficult for nano-YSZ particles to be composited with submicron TiO2 ceramic particles, and the toughening effect cannot be achieved.

Claims

1. A powder material for laser cladding of toughened ceramics, characterized by, by weight percentage, The composition is as follows: Ni: 62-65%, Cr: 16-20%, Al: 6-8%, Ta: 3-5%, Hf: 2-3%, Y: 0.1-0.5%, C: 0.03-0.07%, YSZ: 1-5%, TiO2: 3-6%; wherein the YSZ is nano-sized Y2O3 stabilized ZrO2, and the YSZ is dispersed on the surface of TiO2.

2. The powder material for laser cladding of toughened ceramics according to claim 1, characterized in that, The particle size of the YSZ is 50-100 nm.

3. The powder material for laser cladding of toughened ceramics according to claim 1, characterized in that, TiO2 consists of rutile particles with a particle size of 1-5 μm.

4. The powder material for laser cladding of toughened ceramics according to claim 1, characterized in that, The weight ratio of YSZ to TiO2 is 1:(2-4).

5. A method for preparing a powder material for laser cladding of toughened ceramics as described in claim 1, characterized in that, Includes the following steps: (1) Raw material pretreatment and mixing: YSZ and TiO2 are dry-mixed in a high-energy ball mill for 2 hours in proportion to form nano-YSZ-toughened TiO2 ceramic particles; Ni powder, Cr powder, Al powder, Ta powder, Hf powder, Y powder and the nano-YSZ-toughened TiO2 ceramic particles with a purity ≥99.5% are weighed in proportion and ball-milled to obtain mixed raw materials; (2) Melting treatment: The mixed raw materials are placed in a vacuum induction melting furnace and melted into a uniform alloy liquid; (3) Atomization powder making: The alloy liquid is made into powder by gas atomization or water atomization; (4) Powder post-processing: Sieve to remove unqualified particles and dry to obtain the final powder.

6. The preparation method according to claim 5, characterized in that, In step (1), the ball milling conditions are as follows: using anhydrous ethanol as the medium, wet mixing is carried out for 12-15 hours at a ball-to-material ratio of 8:1 and a rotation speed of 300 r / min.

7. The preparation method according to claim 5, characterized in that, In step (2), when the vacuum degree is <10 -3 Heating to 1650-1700℃ under conditions of Pa and a heating rate of 10-15℃ / min.

8. The preparation method according to claim 5, characterized in that, In step (3), gas atomization uses 3-5MPa argon gas to impact the alloy liquid, and water atomization uses 15-25MPa high-pressure water flow to impact the alloy liquid.

9. The preparation method according to claim 5, characterized in that, Step (3) control the powder particle size to be 45-106μm.

10. The preparation method according to claim 5, characterized in that, Step (4) Dry at 80-100℃ for 2-4 hours.

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