Silicon Based Nanocoatings on Metal Alloys and Their Role in Surface Engineering

Abstract

Metals and their alloys have been widely used in all aspects of science and engineering. However the science of nanotechnology is driving newer demands and requirements for better performance of existing materials and also at a higher level of precision. This is naturally presenting complicated demands on the surface of these metals with a need for surface modification. Self Assembled Monolayers (SAMs) are nanosized coatings that present the most efficient method of carrying out surface modification. Alkylsilanes are silicon based SAMs which are compatible with the majority of metals and alloys. These nanocoatings can serve primary functions such as surface coverage, etch protection and anti corrosion, along with a host of other secondary chemical functions because of their amphiphilic nature. We present a brief introduction to surface modification of metals and alloys followed by a detailed description of silane based nanocoatings and their applications in technology. Then a look at the engineering aspects of these coatings in terms of patterning techniques is presented along with a discussion of the applications of patterned SAMs.

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

“…[17][18][19] Silanes or phosphonates are suitable compounds for those metallic surfaces that are spontaneously covered by their oxides such us Ti, Al, Hf, Zn, Sn, Mg alloys, steel and Ni alloys. 18,[20][21][22][23][24][25][26][27][28][29][30] The terminal OH groups of the oxihydroxide metallic surface react with silanes that undergo hydrolysis forming polysiloxane (Si-O-Si) bonds and Si-O-substrate bonds. 31,32 The formation of a robust bond of the silanes with the substrate confers a strong stability to the layer and allows further chemical functionalization.…”

NIR Photocleavage of the Si–C Bond in Axial Si-Phthalocyanines

“…The Si–C bond, with a substantial bond energy of ∼377 kJ/mol, is ubiquitous in organic reaction synthesis, in natural product synthesis, and in the preservation of the stereochemistry in complex organic molecules . Due to their stability, alkylsilanes are used in a variety of industries including the electrical, electronics, and aeronautical industries and are also promising surfactants in the production of the nanostructured surfaces needed for making complex macroassemblies . Early in the development of the chemistry of methylsilicon phthalocyanines, however, it was observed that while the Si–C bond in these compounds is stable to heat, it is readily photolyzed by near-infrared light in solution, which was utilized synthetically by Kenney and co-workers for developing the photodynamic therapy (PDT) candidate Pc 4, a silicon phthalocyanine bearing two axial ligands consisting of a hydroxyl group and a silylalkyl amine .…”

Stability of phosphonic self assembled monolayers (SAMs) on cobalt chromium (Co–Cr) alloy under oxidative conditions

“…SAMs are a versatile tool to carry out surface modifications[22-24]. They are structures formed by the spontaneous chemisorption of surfactant molecules on surfaces and are typically in the size range of 1-3 nm.…”