Study of a hardened multilayer coating obtained by the cold gas-dynamic spraying with laser intensification

When reconstructing products obtained using additive technologies based on layer-by-layer melting of metal powder by concentrated energy flows, it is advisable to use methods that minimize melting of the initial powder and reduce structural heterogeneity of the material. Cold gas-dynamic spraying with laser-induced intensification of the process (CGDSL) is one of them. The multilayer coatings obtained by the CGDSL method have a homogeneous metal structure though a significant surface roughness attributed to the particle size of the original powder is observed. The goal of the study is to develop a new method of post-processing of multilayer coatings obtained by CGDSL which can provide a hardened layer on their surface. A hardened layer is formed through introduction of boron carbide powder particles into the laser-molten region formed on the surface of the coating based on 316L stainless steel. An acoustic wave triggered by a «microexplosion» induced by a laser pulse above the surface pushes carbide particles in different directions. Some of them are embedded into the melt pool on the surface of the coating. Thus, the laser microdetonation cartooning of the surface of the CGDSL coating is implemeted. Study of the hardened layer revealed a high content of B, C, Cr, Fe, and Ni. Moreover, it is shown that solid carbides of rhombic form are formed in the hardened layer. Chemical and elemental analyzes showed that diamond-shaped carbides — carbides of the type (Fe, Cr)_xB_y — contain a high concentration of Cr, Fe and a relatively small percentage of C. Most likely formation of diamond-shaped carbides occurs due to interaction of chromium which is a part of the initial hardened coating with boron that released from the surface of BC particles under laser impact. The developed method provides hardening of the surface layer of the coating previously obtained by CGDSL by embedding the BC powder particles into the surface. The technology of hardening CGDSL coatings can be implemented using other powder materials.

1. Bagherifard S., Monti S., Zuccoli M., et al. Cold spray deposition for additive manufacturing of freeform structural components compared to selective laser melting / Materials Science and Engineering. 2018. Vol. 721. P. 339 – 350.

2. Bandar AL-Mangour, Phuong Vo, Rosaire Mongrain, Eric Irissou, Stephen Yue. Effect of heat treatment on the microstructure and mechanical properties of stainless steel 316L coatings produced by cold spray for biomedical applications / Thermal spray technology. 2014. N 23(4). P. 641.

3. Coddet P., Verdy C., Coddet C., Debray F., Lecouturier F. Mechanical properties of thick 304L stainless steel deposits processed by He cold spray / Surface & Coatings Technology. 2015. Vol. 277. P. 74 – 80.

4. Gorunov A. I. Features of Coatings Obtained by Supersonic Laser Deposition / Thermal spray technology. 2018. Vol. 27. Issue 7. P. 1194 – 1203.

5. Jianhua Yao, Zhihong Li, Bo Li, Lijing Yang, Jianhua Yaoet. Characteristics and bonding behavior of Stellite 6 alloy coating processed with supersonic laser deposition / Journal of Alloys and Compounds. 2016. Vol. 661. P. 526 – 534.

6. Lupoi R., Sparkes M., Cockburn A., O’Neill W. High speed titanium coatings by supersonic laser deposition / Materials Letters. 2011. Vol. 65. P. 3205 – 3207.

7. Singh R., Rauwald K.-H., Wessel E., et al. Effects of substrate roughness and spray-angle on deposition behavior of cold-sprayed Inconel 718 / Surface & Coatings Technology. 2017. Vol. 319. P. 249 – 259.

8. Yuan Lin-jiang, Luo Fang, Yao Jian-hua, et al. Deposition behavior at different substrate temperatures by using supersonic laser deposition / Journal of Iron and Steel Research International. 2013. Vol. 20. N 10. P. 87 – 93.

9. Jianhua Yao, Lijing Yang, Bo Li, et al. Characteristics and performance of hard Ni60 alloy coating produced with supersonic laser deposition technique / Materials & Design. 2015. Vol. 83. P. 26 – 35.

10. Bo Li, Yan Jin, Jianhua Yao, et al. Solid-state fabrication of WCp-reinforced Stellite-6 composite coatings with supersonic laser deposition / Surface and Coatings Technology. 2017. Vol. 321. P. 386 – 396.

11. Bo Li, Yan Jin, Jianhua Yao, Zhihong Li, et al. Influence of laser irradiation on deposition characteristics of cold sprayed Stellite-6 coatings / Optics and Laser Technology. 2018. Vol. 100. P. 27 – 39.

12. Gorunov A. I. Formation of wear-resistant coatings based on nickel by supersonic laser surfacing / Fiz. Khim. Obrab. Mater. 2016. N 5. P. 59 – 64 [in Russian].

13. Sova A., Grigoriev S., Okunkova A., Smurov I. Cold spray deposition of 316L stainless steel coatings on an aluminum surface with the following laser post-treatment / Surface and Coatings Technology. 2013. Vol. 235. P. 283 – 289.

14. Ivannikov A. Yu., Kalita V. I., Komlev D. I., et al. Investigation into improving microstructure and properties of plasma sprayed Ni coating via electromechanical treatment / Journal of Materials Processing Technology. 2019. Vol. 266. P. 442 – 449.

15. Gorunov A. I. Investigation of the structure and mechanical properties of a corrosion-resistant steel coating formed by gas-dynamic spraying with process activation by laser radiation / Deform. Razrush. Mater. 2016. N 9. P. 2 – 7 [in Russian].

16. Makarov A. V., Sobolev N. N., Malygina I. Yu., Osintseva A. L. Formation of wear-resistant chromium-nickel coating with a particularly high level of heat resistance by combined laser-thermal treatment / Metalloved. Term. Obrab. Met. 2015. N 3(717). P. 39 – 46 [in Russian].

17. Kalita V. I., Yarkin V. V., Bagmutov V. P., et al. The formation of coatings with amorphous and nanostructure / Metally. 2007. N 6. P. 95 – 101 [in Russian].

18. Gorunov A. I. Investigation microstructure of carbon fibers reinforced composite on Fe and Ni-based obtained by laser metal deposition / Surface and Coatings Technology. 2019. Vol. 364. P. 279 – 288.