Wyniki wyszukiwania - BazTech

Ograniczanie wyników

1 Journal of Achievements in Materials and Manufacturing Engineering

1 2011

Znaleziono wyników: 1

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: GIXD technique

Sortuj według:

Ogranicz wyniki do:

The corrosion resistance of zinc-nickel composite coatings

Panek J., Bierska-Piech B., Karolus M.

Journal of Achievements in Materials and Manufacturing Engineering

2011

Vol. 45, nr 2

157--162

Purpose: The aim of this work was to estimate the corrosion resistance of composite Zn+Ni and (Ni-Zn+Ni)/Zn coatings by salt spray test, electrochemical methods and grazing incidence X-ray diffraction (GIXD) method. Design/methodology/approach: The corrosion resistance properties of zinc-nickel coatings in 5% NaCl solution were investigated by salt spray test in 5% NaCl solution and electrochemical methods. Using Stern method the corrosion potential – Ecorr corrosion current density - icorr, and polarization resistance – Rp. have been determined as a measure of corrosion resistance. Phase composition of the corrosion products was determined by X-ray diffraction using Bragg-Brentano and grazing incidence X-ray diffraction (GIXD) methods. Findings: The corrosion resistance of zinc-nickel coatings is dependent on Ni content and it grows with the increase in Ni percentage in the coatings. The higher corrosion resistance could be attributed to the presence of intermetallic Ni2Zn11 phase. The maximum protective ability is reached for the coatings above 40% Ni, where the content of this phase is the highest. The results of salt spray test exhibit the appearance of white rust corrosion, which is characteristic for zinc oxidation process. The main component of corrosion products was Zn5(OH)8Cl22·H2O phase. The products related to the nickel or steel substrate corrosion process were not found. The application of the GIXD technique has allowed to determine the changes in the phase composition of the corrosion products in the zinc and zinc-nickel coatings versus the penetration depth of the X-ray radiation. The presence of corrosion products on the electrode surface results in further improve in their protective ability and the limiting of the corrosion processes. Research limitations/implications: Special attachment for GIXD technique is required for the experiment. Practical implications: The zinc-nickel coatings could be applied as protective coatings for steel substrates. Originality/value: The application of GIXD technique allows to determine the chemical composition of corrosion products along the coating thickness.