Enhancing NiCrBSi coating by the spatial selectivity of in-situ shock wave assisted laser cladding

The composite energy field laser cladding (LC) can improve the mechanical properties of coatings. Based on the spatial selectivity of laser shock, in-situ shock wave assisted LC (in-situ SWALC) was proposed to fabricate NiCrBSi coatings. Firstly, based on the self-developed in-situ SWALC system, four NiCrBSi coatings were prepared on the 16Mn substrate by changing the centre-to-centre distance (CTCD) of two laser spots. Then, the differences of microstructure and element content between LC coating and in-situ SWALC coatings were analyzed. Vickers hardness tester and wear tester were used to compare the influence of CTCD. Finally, based on the theoretical calculation and propagation characteristics of the shock wave, combined with real-time monitoring of the molten pool during the in-situ SWALC process using high-speed imaging, the strengthening mechanism of the in-situ SWALC coatings was revealed. When the CTCD was 0.9 mm, the NiCrBSi coating had the highest hardness and wear properties, which was attributed to the effects of shock wave on the molten pool flow and solidification process. Therefore, the spatial selectivity of in-situ SWALC will play a important role in improving coating performance and energy efficiency, which contributes to the UN Sustainable Development Goal 9 (UN SDG 9).