TY - JOUR
T1 - A combined XPS/ToF-SIMS approach for the 3D compositional characterization of Zr-based conversion of galvanized steel
AU - Cristaudo, Vanina
AU - Baert, Kitty
AU - Laha, Priya
AU - Lyn Lim, Mary
AU - Brown-Tseng, Elizabeth
AU - Terryn, Herman
AU - Hauffman, Tom
PY - 2021/10/1
Y1 - 2021/10/1
N2 - The present study investigates the surface and in-depth characteristics, and deposition mechanism of zirconium-based conversion coatings on hot dip galvanized (HDG) steel substrates for automotive applications, based on zinc galvanizing baths with small additions of aluminium. This contribution provides scientific proof of the chemical heterogeneity both at the surface and along the depth of the Zr-based conversion coatings on galvanized steel. To this purpose, the definition of two derivative model systems – pure zinc and pure aluminium – was indispensable due to Al-enrichment phenomena observed at the galvanized steel surface. A 3D evaluation of the sample chemistry before and after formation of the Zr-based conversion coatings was conducted by a combined approach based on X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) with 1-keV Cs+ sputtering. The experimental results provide direct evidence of the fact that Zr-based conversion coatings on the HDG steel are constituted by a mixed Zn, Al and Zr oxyhydroxide in combination with Zr oxy-/hydroxyfluoride on top of a complex fluoride (hydr)oxide Zn/Al layer, rather than a pure ZrO2 film on top of the galvanized layer mainly made of zinc (and aluminium) as previously reported in the literature.
AB - The present study investigates the surface and in-depth characteristics, and deposition mechanism of zirconium-based conversion coatings on hot dip galvanized (HDG) steel substrates for automotive applications, based on zinc galvanizing baths with small additions of aluminium. This contribution provides scientific proof of the chemical heterogeneity both at the surface and along the depth of the Zr-based conversion coatings on galvanized steel. To this purpose, the definition of two derivative model systems – pure zinc and pure aluminium – was indispensable due to Al-enrichment phenomena observed at the galvanized steel surface. A 3D evaluation of the sample chemistry before and after formation of the Zr-based conversion coatings was conducted by a combined approach based on X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) with 1-keV Cs+ sputtering. The experimental results provide direct evidence of the fact that Zr-based conversion coatings on the HDG steel are constituted by a mixed Zn, Al and Zr oxyhydroxide in combination with Zr oxy-/hydroxyfluoride on top of a complex fluoride (hydr)oxide Zn/Al layer, rather than a pure ZrO2 film on top of the galvanized layer mainly made of zinc (and aluminium) as previously reported in the literature.
KW - hot dip galvanized (HDG) steel
KW - Model zinc and aluminium substrates
KW - SIMS depth profiling
KW - Time-of-flight secondary ion mass spectrometry (SIMS)
KW - X-ray photoelectron spectroscopy (XPS)
KW - Zr-based conversion coatings
UR - http://www.scopus.com/inward/record.url?scp=85107697697&partnerID=8YFLogxK
U2 - 10.1016/j.apsusc.2021.150166
DO - 10.1016/j.apsusc.2021.150166
M3 - Article
AN - SCOPUS:85107697697
VL - 562
JO - Applied Surface Science
JF - Applied Surface Science
SN - 0169-4332
M1 - 150166
ER -