N-Lauroyl sarcosine sodium salt as corrosion inhibitor for type 1518 steel in neutral saline environment

The influence of the sodium salt of N-Lauroyl sarcosine (NLS) on corrosion of a manganese steel was studied in aerated, nearly neutral saline solutions at room temperature and under various hydrodynamic conditions. The inhibitive efficiency of NLS was examined using gravimetric tests, polarization curves and electrochemical impedance spectroscopy (EIS). NLS slowed the corrosion phenomena, either generalized or localized, that occured on steel, but only at high rotation speed of the rotating cylinder electrode (RCE). The mechanism of action eas anodic and probably resulted from the precipitation of an insoluble product on the anodic areas

Inibizione della corrosione di un acciaio al manganese in ambiente neutro

Nel presente lavoro è stata esaminata l'azione che il sale di sodio della N-Lauroil sarcosina (NLS) esercita sulla corrosione di un acciaio al manganese, al variare delle condizioni idrodinamiche di una soluzione aerata di NaCl al 3,5%, a tempertura ambiente. Solo alle elevate velocità di rotazione l'additivo riesce a rallentare i processi di corrosione, sia generalizzata che localizzata, subiti dall'acciaio. Esso svolge una elevata azione inibitrice sul processo anodico di ossidazione del metallo, ma non esercita invece nessun effetto sul processo catodico di riduzione dell'ossigeno. Viene ipotizzato che il responsabile di questo effetto sia un prodotto di precipitazione fra NLS e ioni ferrici

Crystal and magnetic structure of the R15Si9C compounds (R = Ho, Er, Tb)

none5The synthesis of the new compounds R15Si9C with R = Sm, Gd-Er, Y and R15Ge9C with R = Ce, Pr and Nd has been recently reported; these compounds crystallize in the hexagonal La 15Ge9Fe structure type, hP50-P63mc, Z = 2 (ordered superstructure of La5Ge3 (Mn5Si 3-type, hP 16-P63/mcm, Z = 2)). Here we report the results of a neutron diffraction investigation that we have performed to study the crystal and magnetic structures of the R15Si9C compounds with R = Tb, Ho and Er. All three compounds see the establishment of commensurate magnetic order with a predominantly ferromagnetic interaction. Details of mixed antiferro-ferromagnetic spin arrangements (κ = [000]) (for Tb15Si9C and Ho15Si9C) or of purely ferromagnetic ordering (Er15Si9C), and of their temperature dependence, are given and linked to the different coordination of the four dissimilar rare earth sites. In the Tb and Ho compounds the thermal evolution of the magnetic moment values strongly differs between the different R sites. The position occupied by the principal carbon has been determined (Wyckoff site 2b) and the existence of a second position available for the interstitial carbon (Wyckoff site 2a) has been revealed for R = Ho, Tb. Moreover, in the Tb and Ho compounds the magnetic moment value of the rare earth site R4, surrounding the second interstitial carbon site, is strongly reduced if compared to the value on the other rare earth sites. The magnetic transition temperatures of all three compounds, i.e. TC = 130, 43 and 45K for Tb15Si9C, Ho15Si9C and Er 15Si9C, are remarkably high compared to those of the parent R5Si3 compounds. The magnetic behaviour of the partly filled Tb5Si3C0.25 is reported.C. Ritter; F. Wrubl; A. H. Hill; M. Pani; P. ManfrinettiC., Ritter; F., Wrubl; A. H., Hill; Pani, Marcella; Manfrinetti, Pietr

Superstructure and magnetic properties of R15X9C compounds (R = rare earth; X = Si and Ge)

We report the synthesis of the new compounds R15Si9C with R = Sm, Gd-Er, Y and R15Ge9C with R = Ce, Pr and Nd. These compounds crystallize in the hexagonal La15Ge9Fe structure type (hP50, P63mc, Z = 2) which is an ordered superstructure of La5Ge3 (Mn5Si 3-type, hP16, P63/mcm, Z = 2). The superstructure is absent in a single-phase R5Ge3C0.33 alloy with R = Sm and Gd. The addition of interstitial carbon modifies the magnetic properties significantly as regards the magnetic transition temperature and the nature of the magnetic ordering. Carbon doping induces mostly a ferromagnetic or ferrimagnetic configuration. The preponderance of ferromagnetic interactions in the superstructure compounds, with respect to the parent phases, can tentatively be attributed to a change in the sign of the RKKY interactions. The dense Kondo lattice state of Ce in ferrimagnetic Ce5Ge3 is preserved in Ce15Ge9C. Large coercive fields ( 3c4-5 kOe) at low temperatures are observed in most compounds, which exceed 3c50 kOe in the two Sm based compound