Functional Surfaces via Laser Processing in Nickel Acetate Solution

Abstract

This study presents a novel laser processing technique in a liquid media to enhance the surface mechanical properties of a material, by thermal impact and micro-alloying at the subsurface level. An aqueous solution of nickel acetate (15% wt.) was used as liquid media for laser processing of C45E steel. A pulsed laser TRUMPH Truepulse 556 coupled to a PRECITEC 200 mm focal length optical system, manipulated by a robotic arm, was employed for the under-liquid micro-processing. The study’s novelty lies in the diffusion of nickel in the C45E steel samples, resulting from the addition of nickel acetate to the liquid media. Micro-alloying and phase transformation were achieved up to a 30 µm depth from the surface. The laser micro-processed surface morphology was analysed using optical and scanning electron microscopy. Energy dispersive spectroscopy and X-ray diffraction were used to determine the chemical composition and structural development, respectively. The microstructure refinement was observed, along with the development of nickel-rich compounds at the subsurface level, contributing to an improvement of the micro and nanoscale hardness and elastic modulus (230 GPa). The laser-treated surface exhibited an enhancement of microhardness from 250 to 660 HV0.03 and an improvement of more than 50% in corrosion rate.

Microstructure of NbMoTaTiNi Refractory High-Entropy Alloy Coating Fabricated by Ultrasonic Field-Assisted Laser Cladding Process

“…Coatings 2023, 13, x FOR PEER REVIEW 10 of 18 [33]. The SEM images in Figure 9 show that the start of solidification in specimen MT1 is columnar, and in specimen MT2, it is equiaxed.…”

“…Granulation, morphology, grain size, and grain aspect are among the most important factors affecting the mechanical properties of materials that are affected by solidification [33]. The SEM images in Figure 9 show that the start of solidification in specimen MT1 is columnar, and in specimen MT2, it is equiaxed.…”