This work demonstrates for the first time that MePhI compound protects any metallic material against corrosion. This was also proven for an immersion period of 0.5 year. Three analytical approaches were employed: electrochemistry, 3D-profilometry, and X-ray photoelectron spectroscopy (XPS). There was a special focus on XPS surface analysis. The thickness of the MePhI surface layer was determined to be 0.3-0.5 nm by analysing the background of the XPS survey spectrum using the Tougaard method. Furthermore, the orientation and manner of MePhI bonding on the surface is explained especially by examining the XPS excited Auger Cu L3M4,5M4,5 spectra, which is like a “fingerprint” of the Cu(I) MePhI connection. Angle-resolved XPS results showed that both the C and N atoms of the MePhI molecule are involved in the inhibitor surface bonding.
In this work, AISI C1018 lower grade steel material was examined in 20 wt.% methanesulphonic acid (MSA) solutions containing different chemicals to design corrosion inhibitor formulations. These formulations were based on acetylenic alcohol, cinnamaldehyde, 1 dodecylpyridinium chloride, and methanol. It was shown that AISI C1018 steel has to be inhibited in MSA solution and that it is crucial to find the right combination of chemicals to design effective corrosion inhibitor formulations. Electrochemical analyses were carried out in order to test these systems. It was shown that acetylenic alcohol-based formulations significantly improve corrosion inhibition effectiveness compared with the individual corrosion inhibitor components used separately and that they mainly work as mixed-type inhibitors.
In the article the corrosion behaviour of 2205 duplex stainless steel in methanesulphonic acid (MSA) at elevated temperature was investigated. It was proposed that uninhibited MSA could be utilised in acidising procedures in petroleum wells constructed of 2205 duplex stainless steel. It was shown that 2205 duplex stainless steel is highly resistive to corrosion in non inhibited 20 wt.% MSA solution – meaning that it does not contain any corrosion inhibitor. Corrosion rates of 2205 duplex stainless steel in MSA solution with or without 24.13 bar CO2 at 150 °C after 6 h of immersion were lower than what is often required by the petroleum industry. It has to be emphasised that it is uncommon for steel materials to be so resistive in an non inhibited acid solution at elevated temperature, which is the case for MSA.