Oxygen depth profiling in Zn coated steel
Dynamic SIMS is widely used for the microcharacterization of metallurgical samples, thanks to its unique advantages: low detection limits for all species (H-U) including atmospheric species, possibility to use isotopic tracers, and capability to visualize their distribution in three dimensions.
The IMS 7f-Auto unique depth profiling and ion imaging capabilities are applied to studies on a wide variety of materials: diffusion phenomena in polycrystalline samples, surface imaging analysis in alloys, study of inclusions and segregation effects...
C segregation in a steel sample.
Field of view: 250 x 250 μm2.
Hot-dip galvanization is a common process in steel industry: steel is coated with a zinc layer by immersing the metal in a bath of molten zinc (with a 0.3wt% Al amount) at 450°C. Coated steel surface may show undesired and unaesthetic alternated cm-scale bright and matt areas.
On the right, optical image of the coated steel surface showing bright and matt areas.
In this study, dynamic SIMS depth profiling was used to investigate the chemical composition of the two different areas, bright and matt. SIMS technique contributed to the understanding of the formation of the matt areas (caused by the segregation of oxide particles during the coating cooling and solidification). The steel coating process could then be optimized, greatly improving galvanized steel surface visual appearance.
Oxygen and Aluminum SIMS depth profiling obtained on two different areas of the steel sample, bright and matt.
The O concentration over 30-200nm, corresponding to Oxygen segregated after solidification, is significantly higher on matt areas.