Inorganic coatings passive films

Yu et al. (2003) synthesized hybrid thin films containing nanosized inorganic domains from poly(acrylic) and monodispersed colloidal silica with bound 3-(trimethoxysilyl)propyl methacrylate (MSMA) for potential applications as passive films in optical devices. The latter was polymerized with acrylic monomer to form a precursor solution, which was spin-coated and cured to form hybrid films. The silica content in the hybrid thin films was varied from 0 to 50 wt% (Figure 1.302). The coverage area of silica particles by the MSMA decreased with increasing silica content and resulted in the aggregation of silica particles in the hybrid films, and the silica domains were 20-35 nm in size. 

Passive films. Austenitic stainless steels and hardenable stainless steels such as martensitic, precipitation hardening, and maraging stainless steels are seldom coated, but their corrosion resistance depends on the formation of naturally occurring transparent oxide films. These films may be impaired by surface contaminants such as organic compoimds or metallic or inorganic materials. Treatments are available for these materials to clean and degrease surfaces and produce imiform protective oxide films under controlled conditions. These usually involve immersion in an aqueous solution of nitric acid and a dichromate solution. 

The oxidation of thiocyanate is also well-known to cause electrode passivation. Although it is usually attributed to accumulation of electrolysis products, it may be just deactivation of the surface by consumption of the oxide. The latter occurs, for example, with the oxidation of As(III) at a Pt (oxide-coated) electrode.We have found that with an electrode modified with the ruthenium-containing inorganic film, mvRu, the problem is alleviated. The general characteristics of flow injection determinations of thiocyanate with an amperometric detector based on the mvRu electrode are summarized in Table 1. The sample throughput was calculated as described above. 

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