1. Scope
1.1 The guide outlines a protocol for the analysis of thin corrosion films using surface analysis methods. Many air and electrochemically form films on metals are a few nanometers thick and usefully analyzed by a range of surface analysis tools including X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES), and Secondary Ion Mass Spectrometry (SIMS). Many important properties about these thin layers can be extracted using the surface tools and corrosion scientists have been developing approaches to take best advantage of these tools to extract information about passive films since the 1970s.
1.2 The most widely used surface analysis method for corrosion studies is XPS and the protocol focuses primarily on the application of XPS although many aspects of the guide can be applied to AES and other methods. Since AES can often be used to analyze areas smaller than the areas available to XPS, it is particularly useful for pitting and other localized corrosion issues.
1.3 Although some of the approaches described can be extended to relatively thick layers, this guide focuses attention on layers thin enough that both substrate and layer signals can be obtained without removal of the outer layers through a process such as sputter depth profiling. For XPS this means that the film thickness is in the few nanometers range. Since this depth depends on the materials involved, the specific techniques used and some experimental specifics (e.g. the X-ray energy if using XPS), a specific layer thickness is not usefully specified. It is possible to combine the approaches described with material removal methods (including sputter profiling), but they are not discussed in this document.
1.4 This guide describes some of the types of information about corrosion layers and passive films that can be obtained using surface analysis methods and summarizes some of the analysis and data collection approaches can be used to obtain the information. Examples of a few analysis approaches are provided for a sample data set in the annex. Analysis of the sample data set is reported in the literature1 and available in digital form so that analysts can test their specific analysis methods to those previously reported. References to other possible approaches for data collection or analysis are also provided.
To guide non-experts into application of surface tools for corrosion layers.
Keywords
Protocol,
The title and scope are in draft form and are under development within this ASTM Committee.
Citing ASTM Standards
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