Weathering of wood and protection by chromium studied by XPS

作者：Pieter J. de Lange, Adrianus K. de Kreek, A. Van Linden, Norbert J. Coenjaarts · 发表于：Surface and Interface Analysis · 年份：1992 · DOI：10.1002/sia.740190174 · 被引用次数：9 · 研究领域：Cultural Heritage Materials Analysis、Corrosion Behavior and Inhibition、Electron and X-Ray Spectroscopy Techniques

Abstract In order to understand better the protection mechanism of aqueous CrO 3 , the surface of untreated and treated wood, before and after weathering, was studied by XPS. For comparison, the reaction of CrO 3 with filter paper, used as a model compound for cellulose, and with lignin powder was studied as well. Owing to differences in the O/C ratio and the shape of the C 1s signal, cellulose and lignin can be distinguished from each other with the aid of XPS. The low O/C ratio and the high C1 (CC, CH) contribution found for the surface of wood show that the upper layer is enriched with ligin and extractives. Weathering of wood starts with the degradation of lignin, and the appearance of cellulose on the surface increases the O/C ratio and shifts the maximum of the C 1s signal to the C2 (COC, COH) position. Aqueous CrO 3 oxidizes lignin powder and possibly also cellulose. The effect on wood, as observed with XPS, is small. The protection, however, is very clear; the increase of the O/C ratio of CrO 3 ‐treated wood during weathering is much slower than the increase for untreated wood. After weathering, the C 1s signal still resembles the C 1s signal of lignin, so the CrO 3 protects the lignin from degradation.