On the Anti-Corrosion Property of Dry-Gel-Conversion-Grown MFI Zeolite Coating on Aluminum Alloy

MFI zeolite film coated on AA6061 alloy was prepared from fumed silica modified with/without n-octyldecyltrimethoxysilane (ODS) by means of dry gel conversion (DGC) method. The DGC-grown MFI zeolite film could form a strong barrier to protect AA6061 surface against the corrosion from NaCl solution. By using fumed silica as a starting material, the hydrophilicity and anti-corrosion capability of the MFI zeolite film declined with increasing humidity in the DGC synthesis. By silanization with ODS, the surface hydrophobicity of the MFI zeolite film increased, leading to substantial enhancement in anti-corrosion capability. On the other hand, MFI film grown from ODS-modified fumed silica exhibited low hydrophilicity and a much improved anti-corrosion protection property by four orders of magnitude, even stronger than the ODS post-treated MFI film. The strong anti-corrosion capability is attributed to the “thick layer” surface hydrophobicity of zeolite crystal.

Anti-corrosion performances of hybrid silane coatings on AZ31 alloy

Purpose This paper aims to evaluate the efficacy of a zeolite-filled silane sol–gel coating as protective layer on pretreated AZ31 magnesium alloy substrates. Design/methodology/approach Anti-corrosion properties of a silane–zeolite composite coating, at various zeolite content, have been investigated on AZ31 magnesium substrates subjected to different surface pretreatment procedures before coating deposition. A short time etching by hydrofluoric acid (HF) and an anodic polarization in NaOH solution were used as surface pretreatments. Findings High hydrophobicity and good adhesion performances of coatings have been observed. Corrosion protection performance, during immersion in 3.5 per cent NaCl solution, was evaluated by means of electrochemical impedance spectroscopy tests. All coating formulations evidenced good barrier properties. Better durability properties have been shown by coating obtained on HF pretreated magnesium substrate and with a 60 per cent of zeolite content. Originality/value High electrochemical reactivity of magnesium alloys represents the mayor limit of its application in many different fields. In this concern, zeolite-based coatings are emerging as potentially effective environmentally friendly coating for metallic substrates. Despite aluminum and stainless steel substrates, in the literature, only expensive direct synthesis zeolite coating was investigated for its application on magnesium alloys protection. For this reason, this paper fulfills the need to assess the adhesion and anti-corrosion behavior of sol–gel silane–zeolite coating in magnesium alloy substrates.

Synthesis of 5A zeolite coating/PSSF composites and the application for adsorption of methane from air

We fabricated 5A zeolite/PSSF composites and applied it in the end of the fixed bed to improve the bed utilization and to reduce the bed pressure drop.