Derek Beving

Corrosion Resistant High-Silica-Zeolite MFI Coating One General Solution Formulation for Aluminum Alloy AA-2024-T3, AA-5052-H32, AA-6061-T4, and AA-7075-T6

Corrosion resistant high-silica-zeolite (HSZ) MFI coatings have been synthesized by in situ crystallization using a single solution formulation on a series of aluminum alloys with rather different chemical compositions including AA-2024-T3, AA-5052-H32, AA-6061-T4, and AA-7075-T6. The coatings are continuous, compact, and of uniform thickness (similar to 10 mu m). The coatings are demonstrated by using ASTM D 3359B-02 method to have excellent adhesion to all metal substrates tested. The cross-sectional composition analysis shows a gradual and continuous change of Si/Al ratio from pure aluminum at the substrate surface to almost infinity at the free coating surface, and this is suggested to be the origin of excellent of adhesion observed. In addition, a simple detergent solution pretreatment is shown to be adequate for the reproducible formation of high quality coatings. (c) 2006 The Electrochemical Society.

Biocompatibility of corrosion-resistant zeolite coatings for titanium alloy biomedical implants

Titanium alloy, Ti6Al4V, is widely used in dental and orthopedic implants. Despite its excellent biocompatibility, Ti6Al4V releases toxic Al and V ions into the surrounding tissue after implantation. In addition, the elastic modulus of Ti6Al4V ( approximately 110GPa) is significantly higher than that of bone (10-40GPa), leading to a modulus mismatch and consequently implant loosening and deosteointegration. Zeolite coatings are proposed to prevent the release of the toxic ions into human tissue and enhance osteointegration by matching the mechanical properties of bone. Zeolite MFI coatings are successfully synthesized on commercially pure titanium and Ti6Al4V for the first time. The coating shows excellent adhesion by incorporating titanium from the substrate within the zeolite framework. Higher corrosion resistance than the bare titanium alloy is observed in 0.856M NaCl solution at pHs of 7.0 and 1.0. Zeolite coatings eliminate the release of cytotoxic Al and V ions over a 7 day period. Pluripotent mouse embryonic stem cells show higher adhesion and cell proliferation on the three-dimensional zeolite microstructure surface compared with a two-dimensional glass surface, indicating that the zeolite coatings are highly biocompatible.

Corrosion resistant high-silica-zeolite MFI coatings

Abstract Metal corrosion is a ubiquitous problem and generally costs an industrialized country several percent of its gross domestic product. The development of satisfactory protective finishes continues to be of great importance. Many of the protective finishes used today utilize chromium, which in its hexavalent state is a known human carcinogen. We have been investigating the application of zeolite films as chromium-free protective coatings on aluminum alloys and steels [ [1] , [2] , [3] , [4] ]. In this paper we summarize our most recent works that experimentally demonstrates that high-silica-zeolite (HSZ) coating on metal and metal alloys is a viable replacement technology for corrosion protection of metals.