Preparation method of TiCrN ceramic / NiCrBSi alloy three-dimensional interlocking superfine laminated composite coating

Abstract

The invention relates to a preparation method of a TiCrN ceramic / NiCrBSi alloy three-dimensional interlocking superfine laminated composite coating. According to the method, a ceramic phase of a coating system is a TiCrN solid solution formed by introducing Cr into TiN, the melting point of the TiCrN solid solution is reduced by about 350 DEG C compared with TiN (2950 DEG C), the flattening behavior of molten drops is remarkably improved, and submicron precise deposition is achieved; and meanwhile, due to the composition continuity of Cr on the NiCrBSi alloy and the TiCrN ceramic components, better combination can be achieved in a multi-layer structure, and the TiCrN ceramic / NiCrBSi alloy three-dimensional interlocking superfine laminated structure with excellent interface combination is obtained. The obtained coating has high hardness, excellent interface bonding force and wear resistance, and is suitable for surface protection of wear-resistant parts in the fields of aerospace, mechanical manufacturing and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of metal-ceramic composite coating materials, specifically a method for preparing a three-dimensional interlocking ultrafine laminated composite coating of TiCrN ceramic and NiCrBSi alloy using plasma spraying technology. This coating exhibits high hardness, excellent interfacial bonding strength, and wear resistance, making it suitable for surface protection of wear-resistant components in aerospace, machinery manufacturing, and other fields. Background Art

[0002] Compared to Fe- and Co-based alloy coatings, Ni-based alloy coatings offer advantages such as excellent oxidation and corrosion resistance. NiCrBSi alloys, in particular, contain multiple elements that form a hard phase during solidification, enhancing the coating's hardness and high-temperature oxidation resistance. However, pure NiCrBSi alloy coatings still struggle to meet the increasingly stringent demands of engineering applications. Therefore, combining alloys with ceramics to maximize the advantages of each while mitigating the deficiencies of the other has become both a hot topic and a challenge in materials design in recent years. The primary challenge lies in the weak interface between the alloy and ceramic, caused by thermal stress during the preparation process.

[0003] Plasma spraying technology has the advantages of fast deposition speed, small thermal effect on the substrate, controllable coating thickness, wide application range, and stable process. It is an excellent choice for surface protection and remanufacturing of parts. CN 107267908A proposes a method for preparing NiCrBSi-TiN gradient composite coating wear-resistant belt by plasma spraying. In order to alleviate the thermal stress generated during the preparation process and improve the bonding strength of the coating, a gradient distribution of coating components and induction remelting treatment after spraying are used to improve the density of the coating. However, this patented method requires spraying composite coatings with different ratios of NiCrBSi and TiN layer by layer. Repeated replacement of spray powder reduces the spraying efficiency, and the remelting treatment after spraying increases the preparation cost.

[0004] Therefore, how to prepare NiCrBSi-based metal-ceramic composite coatings more efficiently while alleviating the stress concentration problem between the NiCrBSi metal layer and the ceramic layer is a key challenge to improve the service life of the coating, reduce industrial production costs, and promote the large-scale application of plasma spraying technology in the field of high-end equipment remanufacturing. Relevant exploration still needs to be carried out. Summary of the Invention

[0005] In response to the limitations of current technology, the present invention provides a method for preparing a three-dimensional interlocking ultrafine laminated composite coating of TiCrN ceramics / NiCrBSi alloys to relieve the internal stress of the coating and improve the bonding strength. In this method, the ceramic phase of the coating system is formed by introducing Cr into TiN to form a TiCrN solid solution, which has a melting point of about 350°C lower than that of TiN (2950°C), significantly improving the flattening behavior of the molten droplet and achieving submicron-level precision deposition; at the same time, the compositional continuity of Cr in the NiCrBSi alloy and TiCrN ceramic components helps to achieve better bonding in the multilayer structure, obtaining a three-dimensional interlocking ultrafine laminated structure of TiCrN ceramics / NiCrBSi alloys with excellent interface bonding. The coating has high hardness, excellent interface bonding and wear resistance, and is suitable for surface protection of wear-resistant parts in the fields of aerospace, machinery manufacturing, etc.

[0006] The technical solution of the present invention is:

[0007] A method for preparing a TiCrN ceramic / NiCrBSi alloy three-dimensional interlocking ultrafine laminated composite coating, the method comprising the following steps:

[0008] (1) Powder pretreatment: Ti powder and Cr powder were placed in a high-energy ball mill and mechanically mixed for 20-30 min to obtain a mixed powder;

[0009] Wherein, the proportion of Ti powder in the mixed powder is 65wt.% to 85wt.%;

[0010] The particle size of the Ti powder and the Cr powder is 5 to 10 microns; the purity of the Ti powder and the Cr powder is 99.5%.

[0011] The ball mill uses stainless steel grinding balls with a diameter of 4 to 10 mm and a rotation speed of 200 to 300 rad / min.

[0012] (2) Preparation of sodium carboxymethyl cellulose colloid: sodium carboxymethyl cellulose is added to deionized water, stirred, and mixed at 80-90° C. for 2-3 hours to prepare sodium carboxymethyl cellulose colloid;

[0013] Wherein, 1 to 3 g of sodium carboxymethyl cellulose is added to every 100 g of deionized water;

[0014] (3) Preparing a spray granulation slurry: adding sodium carboxymethyl cellulose colloid, mixed powder, and sodium tripolyphosphate dispersant to deionized water, and mixing at room temperature for 2 to 3 hours to obtain a spray granulation mixed slurry;

[0015] Wherein, 120-180g of sodium carboxymethyl cellulose colloid and 1-5g of sodium tripolyphosphate dispersant are added to every 350-450g of deionized water; the mass of the mixed powder is 30-40wt.% of the slurry.

[0016] (4) Spray granulation: The slurry is fed into the atomizer via a peristaltic pump at a speed of 30-40 rad / min. The mixed slurry is fed to the atomizer via an external feed pump at a temperature of 115-120°C. Under the centrifugal force of a high-speed rotating disc, a quasi-spherical (Ti-Cr) composite powder with a particle size of 30-60 μm is obtained.

[0017] The rotation speed of the high-speed rotating disc is 5000-8000 rpm.

[0018] (5) Spray powder preparation: Quasi-spherical (Ti-Cr) composite powder prepared by spray granulation and spherical NiCrBSi powder (40-90 μm) were mixed in a mass ratio to obtain spray powder;

[0019] Among them, the mass ratio of (Ti-Cr) composite powder to NiCrBSi powder is 3:7;

[0020] The content of NiCrBSi powder is 14-18 wt.% of Cr, 3-4.5 wt.% of B, 3.5-5.5 wt.% of Si, and the balance of Ni.

[0021] The particle size of NiCrBSi powder is 40-90 μm.

[0022] (6) Matrix treatment: After cleaning the matrix material, perform sandblasting;

[0023] The surface roughness of the obtained substrate is 3 to 10 μm.

[0024] (7) Spraying process: spraying NiCrAlY bonding primer on the surface of the substrate after sandblasting, with a thickness of 80-100 μm;

[0025] Then, the spray powder obtained in step (5) is sprayed on the substrate surface by plasma spraying combined with self-propagating combustion synthesis to prepare a TiCrN / NiCrBSi composite coating with a thickness of 300 to 500 μm;

[0026] The powder feeding gas is N2 at a flow rate of 0.4-0.5 L / min; the working gases are Ar and N2, with an ionization gas flow rate of 40-50 L / min. Each spraying time is 20-30 seconds, and the spraying thickness is 70-100 μm.

[0027] In the step (6), the substrate is made of metal or ceramic material.

[0028] The metal is specifically 45# steel or titanium alloy; the ceramic is specifically SiC or Al2O3;

[0029] In the step (7), the spraying power is 30-40 kW and the spraying distance is 80-100 mm.

[0030] The essential features of the present invention are:

[0031] The present invention uses TiCrN ceramic as the reinforcing phase. The introduction of Cr reduces the melting point of TiCrN by approximately 350°C compared to TiN (2950°C), significantly improving the flattening behavior of the molten droplet. Furthermore, the presence of Cr in the NiCrBSi alloy promotes compatibility between the metal layer and the ceramic layer, forming a more coherent interface structure and reducing interface defects. This compositional continuity facilitates better bonding in multilayer structures. The TiCrN ceramic / NiCrBSi alloy three-dimensional interlocking ultrafine laminated composite coating eliminates the need for post-processing such as high-temperature heat treatment and remelting after plasma spraying, reducing costs.

[0032] The beneficial effects of the present invention are:

[0033] The present invention addresses the problem of stress between the metal layer and the ceramic layer prepared by current plasma spraying, and provides a method for preparing a three-dimensional interlocking ultrafine laminated composite coating of TiCrN ceramic / NiCrBSi alloy. This method uses the gas phase reaction of Ti, Cr and N2 during the spraying process to introduce Cr into the TiN lattice to generate molten TiCrN ceramic droplets, which are deposited synchronously with NiCrNSi and well flattened and spread. The continuity of Cr components is conducive to better bonding between layers, and a metal-ceramic three-dimensional interlocking ultrafine laminated structure is formed in the coating above 300um. The hard ceramic layer provides high load-bearing capacity, the soft alloy layer absorbs energy, and the fine layered structure relieves stress concentration inside the coating. The hardness of this composite coating system is higher than that of traditional NiCrBSi coating (~600HV 0.2 ) increased by 69%, and the critical interlayer load value of the composite coating reached 110.15N. The phase / interlayer bonding was excellent, and no post-processing was required, which was both process feasible and economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is an SEM image of the spherical (Ti-Cr) composite powder prepared by spray granulation in Example 1.

[0035] Figure 2 is a surface XRD pattern of the TiCrN ceramic / NiCrBSi alloy composite coating prepared in Example 1;

[0036] Figure 3 is a surface SEM image of the TiCrN ceramic / NiCrBSi alloy composite coating prepared in Example 1;

[0037] Figure 4 is a cross-sectional SEM image of the TiCrN ceramic / NiCrBSi alloy composite coating prepared in Example 1;

[0038] Figure 5 1 is a graph of the acoustic signal of the scratch test of the TiCrN ceramic / NiCrBSi alloy composite coating prepared in Example 1; DETAILED DESCRIPTION

[0039] Example 1

[0040] Ti powder (85 wt.%) and Cr powder (15 wt.%) were weighed and mixed. The Ti and Cr powders had a particle size of 5 to 10 μm and a purity of 99.5%. The weighed Ti and Cr powders were placed in a high-energy ball mill and mechanically mixed at 200 rad / min for 30 minutes. The mill used stainless steel balls with diameters of 4 mm, 6 mm, and 10 mm, respectively, in a mass ratio of 1:4:1.

[0041] Sodium carboxymethylcellulose (3 g) was added to deionized water (200 g) and stirred at 80°C for 2 h to prepare a sodium carboxymethylcellulose colloid. The resulting mechanically mixed raw material powder (300 g), sodium carboxymethylcellulose colloid (150 g), sodium tripolyphosphate dispersant (3 g) and deionized water (407 g) were mixed with an electric stirrer for 2 h to uniformly mix the slurry. The solid (raw material powder) content in the slurry was 35 wt.%. When the inlet temperature of the spray granulation equipment was 120°C, the slurry was fed into an atomizer via a peristaltic pump. The atomizer's high-speed rotating disk rotated at a speed of 5000 rpm (to allow the slurry to be ejected at high speed and rapidly vaporized in contact with hot air). After the spray granulation was completed, the slurry was sieved to obtain a reconstructed spherical powder ((Ti-Cr) powder) with a particle size of 30 to 60 μm.

[0042] The 45# steel substrate was cleaned with alcohol and then sandblasted using a TPS-1 pneumatic sandblaster (to a roughness of 5 μm, creating a rough surface that enhances the adhesion between the coating and the substrate). An 80-100 μm thick NiCrAlY metal bonding primer was then sprayed onto the sandblasted surface. A composite powder was then sprayed onto the bonding primer surface using a mixture of Ti-Cr powder and NiCrBSi powder (16.19 wt.% Cr, 3.2 wt.% B, 4.21 wt.% Si, with the balance being Ni, and a particle size of 40-90 μm) in a mass ratio of 3:7. This composite powder was then mixed with the bonding primer to produce a 350 μm thick TiCrN / NiCrBSi composite coating. The powder feed gas was N2 at a flow rate of 0.4 L / min. Ar (at a flow rate of 40 L / min) and N2 (at a flow rate of 50 L / min) were used as the working gases. Each spraying time is 20s, each spraying thickness is 70μm, and the spraying power is 35kW.

[0043] The phase analysis of the composite coating of the sprayed sample was carried out using a Smart Lab X-ray diffractometer produced by Rigaku Corporation of Japan, and the morphology was observed using an S-4800 / TMP cold-field emission scanning electron microscope produced by HITACHI of Japan. The bonding strength of the composite coating was evaluated using a WS-2005 coating adhesion automatic scratch tester, and the wear resistance of the coating was tested using a GF-I reciprocating friction and wear tester.

[0044] The phases of the obtained TiCrN / NiCrBSi composite coating are detected as follows:

[0045] Figure 1 The morphology of the (Ti-Cr) composite powder prepared in this experiment is shown in Figure 2. After spray granulation, the powder has good overall sphericity, is relatively dense, and has a smooth surface. The particle size is mostly between 30-60 μm.

[0046] Figure 2 The surface XRD pattern of TiCrN / NiCrBSi composite coating prepared in this experiment. The composite coating is mainly composed of γ-Ni, Cr 1.12 Ni 2.88 It is composed of alloy phase, CrB hard phase, TiCrN strengthening phase and Ti3O phase.

[0047] Figure 3 This is the surface SEM image of the TiCrN / NiCrBSi composite coating prepared in this experiment. The light gray area is the Ni-based alloy phase, and the dark gray area is the TiCrN ceramic phase. The two phases are staggered and fused with each other, and the interface is well bonded. There are no cracks and pores at the phase interface. It can be considered that the two-phase droplets are stacked or adjacent in the spreading position, and adhere to each other and solidify to achieve a good bonding state of interface fusion, alleviating the problem of easy shedding of the hard phase in the composite coating during wear.

[0048] Figure 4 This is a cross-sectional SEM image of the TiCrN / NiCrBSi composite coating prepared in this experiment. The coating is approximately 350 μm thick and dense, exhibiting typical layered structural characteristics. The Ni-based alloy phase and TiCrN ceramic phase are stacked layer by layer, with fine individual layers and tight interlayer bonding without delamination. This indicates that the molten droplet is fully flattened upon impact with the substrate during the spraying process. This interlaced structure of soft and hard phases achieves better performance than a single homogeneous coating.

[0049] Figure 5 The scratch acoustic signal diagram of the TiCrN / NiCrBSi composite coating prepared in this experiment under the conditions of loading load 120N, loading rate 100N / min, and scratch length 5mm. The critical load value of the composite coating is 80.45N and the average hardness is 1012.9HV 0.2Under the conditions of loading load 15N, rotation speed 200rad / min, reciprocating length 5mm, and grinding ball Si3N4, the friction coefficient at room temperature is 0.769 and the wear volume is 0.077mm. 3 Although this coating exhibits a high average microhardness, the TiCrN ceramic phase is highly brittle, and the coating easily breaks and peels under applied load. As evidenced by the slight signal fluctuations during the loading phase preceding fracture failure, this is related to the coating's microstructure, hardness, defects, or the occurrence of minor cracks and plastic deformation.

[0050] Example 2

[0051] Except for the different weighing ratios of Ti powder (80 wt.%) and Cr powder (20 wt.%), the adopted method and control parameters are the same as those in Example 1.

[0052] The morphology and XRD pattern of the spray granulated spherical powder prepared by the above method are the same as those in Example 1. The thickness of the prepared TiCrN / NiCrBSi composite coating is about 350 μm, the critical load value is 88.55 N, and the average hardness is 973.15 HV 0.2 , the friction coefficient at room temperature is 0.712, and the wear volume is 0.068mm 3 .

[0053] Example 3

[0054] Except for the different weighing ratios of Ti powder (75 wt.%) and Cr powder (25 wt.%), the adopted method and control parameters are the same as those in Example 1.

[0055] The morphology of the spray-granulated spherical powder prepared by the above method is the same as that of Example 1. Due to the increase in Cr content, XRD test results show that the Cr element exceeding the solid solubility limit exists in the coating as elemental Cr. The continuity of Cr composition in the NiCrBSi alloy and TiCrN ceramic components enables the multilayer structure of the coating to have better interlayer bonding. The composite coating has a coating thickness of about 350μm, a critical load value of 93.65N, and an average hardness of 951.15HV 0.2 , the friction coefficient at room temperature is 0.663, and the wear volume is 0.051mm 3 .

[0056] Example 4

[0057] Except for the different weighing ratios of Ti powder (70 wt.%) and Cr powder (30 wt.%), the adopted method and control parameters are the same as those in Example 1.

[0058] The morphology of the spray granulated spherical powder prepared by the above method is the same as that of Example 1. As in Example 3, the presence of elemental Cr was detected in XRD, and a light gray elemental Cr phase was observed at the interface between the TiCrN phase and the NiCrBSi phase in the surface and cross-sectional SEM morphology images, indicating that the interface bonding degree was improved. The coating thickness of the composite coating was about 350 μm, the critical load value was 95.75 N, and the average hardness was 936.32 HV. 0.2 , the friction coefficient at room temperature is 0.657, and the wear volume is 0.045mm 3 .

[0059] Example 5

[0060] Except for the different weighing ratios of Ti powder (65 wt.%) and Cr powder (35 wt.%), the adopted method and control parameters are the same as those in Example 1.

[0061] The morphology of the spray-granulated spherical powder prepared by the above method is the same as that of Example 1. As in Examples 3 and 4, the presence of elemental Cr was detected in XRD, and the proportion of light gray elemental Cr phase at the interface between the TiCrN phase and the NiCrBSi phase in the surface and cross-sectional SEM morphology images increased significantly. The enrichment of the Cr element (tough phase) at the interface between the two phases can hinder crack propagation, while alleviating the difference in thermal expansion coefficients between the two phases, promoting close bonding between the layers, and having a higher ability to withstand external forces. The coating thickness of the composite coating is about 350 μm, the critical load value is 110.15 N, and the average hardness is 927.00 HV 0.2 , the friction coefficient at room temperature is 0.660, and the wear volume is 0.043mm 3 .

[0062] The above results show that the TiCrN / NiCrBSi composite coating prepared by the present invention has excellent bonding between the metal phase and the ceramic phase, forming a metal-ceramic three-dimensional interlocking ultra-fine laminated structure in the coating above 300um. The hard ceramic layer provides high load-bearing capacity, the soft alloy layer absorbs energy, and the fine layered structure and the interphase Cr element effectively alleviate the stress concentration within the coating. At the same time, the periodic interface formed between the metal layer and the ceramic layer can disperse the thermal stress concentration, and the stress caused by the thermal expansion difference is offset by the synergistic effect of the plastic deformation and elastic deformation between the layers. The ductility of the metal layer can absorb the contraction stress generated by the ceramic layer during the cooling process, thereby improving the density and bonding strength of the coating, and to a certain extent, improving the critical load value of the composite coating and improving the wear resistance of the coating.

[0063] Matters not covered by the present invention are known technologies.

Claims

1. A method for preparing a TiCrN ceramic / NiCrBSi alloy three-dimensional interlocking ultrafine laminated composite coating, characterized by: The method comprises the following steps: (1) Powder pretreatment: Ti powder and Cr powder were placed in a high-energy ball mill and mechanically mixed for 20-30 min to obtain a mixed powder; Wherein, the proportion of Ti powder in the mixed powder is 65wt.% to 85wt.%; (2) Preparation of sodium carboxymethyl cellulose colloid: sodium carboxymethyl cellulose is added to deionized water, stirred, and mixed at 80-90° C. for 2-3 hours to prepare sodium carboxymethyl cellulose colloid; Wherein, 1 to 3 g of sodium carboxymethyl cellulose is added to every 100 g of deionized water; (3) Preparing a spray granulation slurry: adding sodium carboxymethyl cellulose colloid, mixed powder, and sodium tripolyphosphate dispersant to deionized water, and mixing at room temperature for 2 to 3 hours to obtain a spray granulation mixed slurry; Wherein, 120-180g of sodium carboxymethyl cellulose colloid and 1-5g of sodium tripolyphosphate dispersant are added to every 350-450g of deionized water; the mass of the mixed powder is 30-40wt.% of the slurry; (4) Spray granulation: The slurry is fed into the atomizer through a peristaltic pump. Under the centrifugal force of the high-speed rotating disc, the slurry is thrown out. When it comes into contact with hot air, the water vaporizes to obtain a quasi-spherical (Ti-Cr) composite powder with a particle size of 30 to 60 μm. (5) Spray powder preparation: Quasi-spherical (Ti-Cr) composite powder prepared by spray granulation and spherical NiCrBSi powder (40-90 μm) were mixed in a mass ratio to obtain spray powder; Among them, the mass ratio of (Ti-Cr) composite powder to NiCrBSi powder is 3:7; (6) Matrix treatment: After cleaning the matrix material, perform sandblasting; The substrate is made of metal or ceramic material; (7) Spraying process: spraying NiCrAlY bonding primer on the surface of the substrate after sandblasting, with a thickness of 80-100 μm; Then, the spray powder obtained in step (4) is sprayed on the substrate surface by plasma spraying combined with self-propagating combustion synthesis to prepare a TiCrN / NiCrBSi composite coating with a thickness of 300 to 500 μm; Among them, the powder feeding gas is N2, and the flow rate is 0.4-0.5L / min; the working gas uses Ar (gas flow rate is 40-50L / min) and N2 (gas flow rate is 40-50L / min); each spraying time is 20-30s, and each spraying thickness is 70-100μm.

2. The method for preparing the TiCrN ceramic / NiCrBSi alloy three-dimensional interlocking ultrafine laminated composite coating according to claim 1, characterized in that: In step (1), the particle size of the Ti powder and the Cr powder is 5 to 10 microns; the purity of the Ti powder and the Cr powder is 99.5%.

3. The method for preparing the TiCrN ceramic / NiCrBSi alloy three-dimensional interlocking ultrafine laminated composite coating according to claim 1, characterized in that: The ball mill uses stainless steel grinding balls with a diameter of 4 to 10 mm and a rotation speed of 200 to 300 rad / min.

4. The method for preparing the TiCrN ceramic / NiCrBSi alloy three-dimensional interlocking ultrafine laminated composite coating according to claim 1, wherein: In step (4), the rotation speed of the high-speed rotating disc is 5000-8000 rpm; the rotation speed of the peristaltic pump is 30-40 rad / min; and the temperature of the atomizer is 115-120°C.

5. The method for preparing the TiCrN ceramic / NiCrBSi alloy three-dimensional interlocking ultrafine laminated composite coating according to claim 1, characterized in that: In step (5), the content of NiCrBSi powder is 14-18 wt.% of Cr, 3-4.5 wt.% of B, 3.5-5.5 wt.% of Si, and the balance of Ni; the particle size of the NiCrBSi powder is 40-90 μm.

6. The method for preparing the TiCrN ceramic / NiCrBSi alloy three-dimensional interlocking ultrafine laminated composite coating according to claim 1, characterized in that: The metal described in step (6) is specifically 45# steel or titanium alloy; the ceramic is specifically SiC or Al2O3.

7. The method for preparing the TiCrN ceramic / NiCrBSi alloy three-dimensional interlocking ultrafine laminated composite coating according to claim 1, characterized in that: In the step (7), the spraying power is 30-40 kW and the spraying distance is 80-100 mm.

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