Surface Chemical Analysis at the Micro- and NanoScale
This chapter describes relevant methods of micro- and nanosurface chemical analysis used in technical diagnostics. Informative case studies in diagnostics applied in a wide range of industrial technology are presented, too.
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Wolfgang E. S. Unger and Vasile-Dan Hodoroaba
This chapter describes relevant methods of micro- and nanosurface chemical analysis used in technical diagnostics. Informative case studies in diagnostics applied in a wide range of industrial technology are presented, too.
15.1
Introduction
For a selection and application of technical diagnostic methods, the character of the item under consideration and the length- and timescales associated with damage initiation and evolution must be considered (cf. Fig. 1.2). Nowadays, micro- and nanotechnology is an important driver in many fields. Therefore, concepts of technical diagnostics have to be appropriately extended from those which have been conventionally applied to macrotechnology. Reliability considerations have to be widened to cover micro- and nanoreliability. Consequently, surface chemical analysis at the micro- and nanoscales is an indispensable element of the deductive conceptual approach of technical diagnostics today. All the classes of engineering materials listed in Chap. 2 of this book are accessible to the modern methods of
W. E. S. Unger (&) V.-D. Hodoroaba BAM Bundesanstalt für Materialforschung und– prüfung, Unter den Eichen 87, 12200, Berlin, Germany e-mail: [email protected]
micro- and nanosurface chemical analysis. Usually, the materials a technical item is made of are subject to ‘‘loads’’, meaning any physical process acting on the component (cf. Chap. 3). One of those loads is the interaction with the component’s specific environment which may affect the material’s integrity. Micro- and nanosurface chemical analysis is particularly useful in studying tribo-chemical and environmental loads. The latter ones are derived from exposure to radiation or reactive chemical species leading to ageing, corrosion and gas-phase embrittlement. Examples are presented in the Sect. 15.6. Surface chemical analysis has to be applied (1) when areas of interest characterized by different chemical composition have to be identified on a technical item’s surface, (2) to determine the concentrations of constituents, elements or compounds in these areas of interest and (3) to measure the variation of composition in all three dimensions. In-depth analysis is enabled by the combination of the analytical method with ion sputtering or sectioning techniques as focused ion beam (FIB) milling. A relevant parameter is the information depth of an individual analysis method. It may vary from some 10 lm to only a small number of atomic layers, depending on the analytical technique used. The most versatile methods of surface chemical analysis are energy-dispersive X-ray spectroscopy (EDX) [1], electron spectroscopy for chemical analysis (ESCA) [2], auger electron spectroscopy
H. Czichos (ed.), Handbook of Technical Diagnostics, DOI: 10.1007/978-3-642-25850-3_15, Ó Springer-Verlag Berlin Heidelberg 2013
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W. E. S. Unger and V.-D. Hodoroaba
Table 15.1 Survey on methods of surface chemical analysis most relevant for technical diagnostics Method
Probe
EDX, ED-EPM
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