| WANG Bo,YU Min,LYU Peiyuan,CHEN Hui.Effect of Cu Transition Layer on Performance of Cold Sprayed CuCrZr Coating[J],53(17):196-201 |
| Effect of Cu Transition Layer on Performance of Cold Sprayed CuCrZr Coating |
| Received:October 12, 2023 Revised:March 05, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.17.018 |
| KeyWord:CuCrZr crystallizer cold spraying Cu transition layer heat conduction |
| Author | Institution |
| WANG Bo |
Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu , China |
| YU Min |
Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu , China |
| LYU Peiyuan |
Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu , China |
| CHEN Hui |
Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu , China |
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| Abstract: |
| Cold spraying has become a potential technology for repairing continuous casting crystallizer due to its advantages of small thermal impact, no damage to the substrate and unrestricted shape of the repair workpiece. At present, the crystallizer material commonly used for continuous casting is CuCrZr alloy, but the thermal expansion coefficient difference between the CuCrZr substrate and the cold-hardened coating is large, and the interface between the coating and the substrate is very likely to crack under the service conditions of the crystallizer with rapid cooling and heating. Therefore, the introduction of Cu particles with good plastic deformation ability was considered as an intermediate layer between the cold sprayed CuCrZr coating and the CuCrZr substrate to solve the cracking problem at the interface of the CuCrZr coating, and the influence of the Cu transition layer on the organization and properties of the CuCrZr coating was investigated, so as to provide a new idea for the repair of the copper crystallizer by cold spraying. With high-pressure nitrogen as the working gas, compressed air as the powder feeding gas, cold spraying technology was used in the CuCrZr substrate to prepare a layer of Cu coating primer, and then a multi-layer CuCrZr coating was sprayed. The CuCrZr and Cu powder were spherical, with a particle size range of 10-100 μm. The average size was 30.2 μm and 34.4 μm, respectively. The substrate material was CuCrZr, and sandblasting was performed before coating. The cold spraying distance was 20 mm, the spraying speed was 20 mm/s, the powder feeding rate was 20 g/min, the pressure was 3.4 MPa, and the temperature was 500 ℃. Axio Oberver A1m Zeiss inverted metallurgical microscope and scanning electron microscope were used to observe the coating organization, combined with Image-J software to count the coating porosity and flattening. A DHV-1000ZTRDT microhardness tester was used to characterize the coating hardness. The thermal conductivity was determined with a NETZSCH LFA-427 Laser Thermal Conductivity Meter at test temperature of 50 ℃, 250 ℃, and 500 ℃, and the specimens were ϕ10 mm×2.7 mm discs. It was found that the Cu+CuCrZr coating was well combined with the interface of the substrate, and the thickness of the Cu coating was about 50 μm, and the CuCrZr coating was deposited on the top of the Cu coating sequentially. The porosity of the coating was about 0.624%, and the flattening rate of CuCrZr particles was (43.62±4.54)%. The hardness of the CuCrZr substrate was about 160HV, and there was a work-hardening layer of the substrate near the interface, with the hardness of about 163HV- 168HV, and the thickness of about 160 μm. The average hardness of the Cu coating was about 153HV, and that of the cold-sprayed CuCrZr coating was about 173HV. The thermal conductivity of the coating increased with the increase of test temperature, which arrived at the value of the substrate at 500 ℃. The Cu transition layer promoted a good bonding between the coating and the substrate, and thus effectively prevented the cracking of CuCrZr coating from the CuCrZr plate. The use of Cu+CuCrZr coating can meet the mechanical and thermal conductivity requirements of the CuCrZr crystallizer. |
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