The Effect of Laser Shock Peening on the Corrosion Behavior of Biocompatible Magnesium Alloy ZK60

Abstract

The influences of different laser power density in LSP (laser shock peening) on the corrosion performance of biocompatible magnesium alloy ZK60 were researched via SBF (Simulated Body Fliud) immersion testing and electrochemical testing. Corrosion morphology and corrosion products were observed and analyzed using SEM (Scanning Electron Microscope) outfitted with EDS (Energy Dispersive Spectrometer) and XRD (X-ray Diffraction). Simultaneously, 3D morphology, surface roughness, residual stress, and microstructure were also characterized. Results reveal that the modified samples can obtain higher residual compressive stress, which can lead to lower degradation rates in SBF solution. In terms of the weight loss of the samples, corrosion resistance increased by 52.1% maximally. The corrosion potential of modified samples in the SBF solution positively shifted from −1.3884 V to −1.1094 V and the corrosion current density decreased by 13.2% at most. The anti-corrosion ability of ZK60 is significantly enhanced by the LSP process.

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“…This phenomenon can be evaluated as negative because can spoil the appearance of the product, however, in the case of using a magnesium alloy to create biodegradable implants, this parameter, on the contrary, promotes better cell adhesion and growth of inert tissue. Chemical analysis showed an increase in the proportion of calcium and fluorine content (Figure 17), which also demonstrates the applicability of ZK60 alloy processed by the LSP method in the production of biodegradable implants [159]. After the surface treatment with the LSP method, the weight loss in corrosion tests of alloy ZK60 in simulated body fluid (SBF) solution was reduced by 52%, and the overall corrosion resistance increased by 20% [159].…”

“…Chemical analysis showed an increase in the proportion of calcium and fluorine content (Figure 17), which also demonstrates the applicability of ZK60 alloy processed by the LSP method in the production of biodegradable implants [159]. After the surface treatment with the LSP method, the weight loss in corrosion tests of alloy ZK60 in simulated body fluid (SBF) solution was reduced by 52%, and the overall corrosion resistance increased by 20% [159].…”

“…A promising method of surface treatment with a laser beam is primarily due to the ability to effectively transfer a certain amount of thermal energy to a given depth of the alloy surface. Method of surface treatment with a laser beam like laser shock peening (LSP) process consists of fast surface treatment with a laser [43,159,160]. As a result, a shock wave is generated due to an increase in the volume of the plasma arc on the surface.…”

“…Due to this, a change in the microstructure of the surface layer occurs. To increase the surface treatment effect (increase the cooling rate of the melted layer), the treatment is carried out through a layer of water, and the surface is painted with dark paint for better energy absorption [159]. When exposed to LSP, the chemical composition of the base metal remains the same; there is no possibility of adding alloying components to increase the corrosion resistance.…”

“…In addition, an improvement in characteristics such as material hardness and fatigue strength can be observed. After the surface treatment with the LSP method, the weight loss in corrosion tests of alloy ZK60 in simulated body fluid (SBF) solution was reduced by 52%, and the overall corrosion resistance increased by 20% [159].…”