The microstructure of steels after mechanical polishing is revealed only by the application of a suitable etchant. To achieve adequate optical or electron microscope images, the specimen surface must be free of any artifacts. Chemical etching can be defined as a controlled corrosion process. The metal of the investigated material passes as cations into the etchant solution during the chemical etching reaction. Chemical etching is usually performed manually either by immersing the sample in the etchant with simultaneous stirring or by swabbing with a lint-free cloth soaked in the etchant. It is also extremely important to debug the process of removing the sample from the bath and subsequent cleaning. It is recommended to wash the sample after removal from the etchant with water (distilled or demineralized) or alcohol (ethanol, methanol, or isopropyl alcohol) and dry it properly (depending on the etchant and the etched material). The main problem with these processes is the human factor, which significantly contributes to the already limited repeatability. All operation steps must be performed by properly trained personnel in the field of occupational safety because hazardous substances are handled. A high manual dexterity is also needed. Training a new employee is a long-term process. Moreover, keeping the exact etching time can be a challenge and one second can decide success. These problems become more serious in the case of using surface sensitive analytical method, such as a low energy scanning electron microscopy, due to the high spatial resolution and extreme surface sensitivity. We have developed an apparatus for automatic etching of metallographic samples of purpose to overcome all above-mentioned difficulties. The apparatus and results of the first experiments will be presented.
