Optimization of the surface properties of nanostructured Ni–W alloys on steel by a mixed silane layer

Abstract

Ni-W nanostructured coatings electrodeposited on steel by galvanostatic pulses were functionalized by tetraethoxysilane (TEOS) and octadecyltrichlorosilane (OTS) in a two-step procedure. A silica-rich layer is formed by the reaction of TEOS with the metal coating surface oxides, which allows a further reaction with OTS forming a hydrocarbon-silica outer network. This mixed silane layer provides hydrophobicity and improves the corrosion behavior of the Ni-W surface coatings without modifying their excellent mechanical properties.

Phosphonic acid functionalization of nanostructured Ni–W coatings on steel

“…Morover, the total O/P atomic ratio is about 10, much higher than that expected for stoichometric Ni or W phosphonates.The covalent attachment to form P-O-Me bonds is demostrated by comparing the P spectra with that obtained for pure ODPA (Figure 4) It should be noted that the phosphonate layer becomes more efficient than that obtained by Ni-W functionalization with tetraethoxysilane (TEOS) which exhibits γ = 90. [18] In this case the TEOS layer needs to be improved by an additional step adding octadecyltrichlorosilane to obtain a contact angle (γ = 119) [18] similar to that found on the Ni-W&ODPA surface. The value γ = 114 ○ is similar to those measured for phosphonate coatings on stainless steel (γ = 108 ○ ), Nitiol (γ = 107), nickel (γ = 109 ○ ) and titanium (γ = 96 ○ ).…”

“…[15] Silane chemistry offers many alternatives to surface functionalization but in many cases, the poor hydrolytic stability of the siloxanes and polymerization reactions limit a precise control of the composition and structure of the layer. [16][17][18][19] Phosphonic acids (R-PO3H2) have a reactive head that forms robust and stable P-O-metal bonds and an organic tail that confers a high degree of order to these 2D or 3D metal organic frameworks. [15,20] The P-O-metal bond can vary from ionic to covalent as a function of the identity and oxidation state of the metal ion.…”

A van der Waals DFT study of chain length dependence of alkanethiol adsorption on Au(111): physisorption vs. chemisorption

“…Hence in the recent years several density functional theory (DFT) studies (some of which also use van der Waals corrections) have been employed to study longer chain thiol SAMs. [27][28][29][30][31][32][33][34][35] Nevertheless in almost all of these computational studies the longest thiol studied was C6 and mostly standing up high density films were examined with the aim of determining most favored gold surface reconstruction which seems to be RS-Au adatom -SR.…”

Designing Stainless Steel Surfaces with Anti‐Pitting Properties Applying Laser Ablation and Organofluorine Coatings

“…In spite of this, several bands coming from the silane network, which is obtained after the hydrolysis of FOTS molecules and their subsequent reaction with the metal substrate, are clearly identified. More specifically, the main absorption bands of the coating are due to the vibrations of the CH 2 aliphatic groups (2912 cm −1 , 2844 cm −1 , 1471 cm −1 , 1425 cm −1 ), the O–Si–O and C–Si–O linkages (1247 cm −1 , 1218 cm −1 ), and the CF 2 and CF 3 groups (1147 cm −1 , 715 cm −1 , 707 cm −1 , 655 cm −1 ) . Obviously, the FTIR spectra recorded for silanized patterned surfaces (not shown) are very similar to that displayed in Figure a.…”