Thermal spraying is a metal surface strengthening technology that atomizes and sprays molten spraying materials on the surface of parts through Jet stream to form a spraying layer. By using this technology, a solid covering layer is formed on the surface of the workpiece, which we call&# quo; Coating”, With this special coating, the surface of the workpiece has achieved various special physical and chemical properties such as hardness, wear resistance, corrosion resistance, heat resistance, insulation, conductivity, sealing, oxidation resistance, disinfection, and microwave radiation resistance. To meet various application requirements.

    Metallographic testing is one of the important methods used to evaluate the quality of coatings. Through metallographic testing, the microstructure of the coating, defects such as pores, cracks, inclusions, and the bonding between the coating and the substrate can be visually observed, thus determining the quality of the coating.

    We take the widely used TSC and TBC metal anti-corrosion coatings as examples to explore the preparation method of their metallographic samples.

    There are no special requirements for cutting sampling. Large size grinding wheel cutting and wire cutting can be used. Our sample uses linear precision cutting from the QMAXIS metallographic equipment. The vacuum infiltration cold embedding method of low viscosity epoxy resin is mainly used for embedding, which will not damage the spatial morphology of coating voids due to pressure, so hot pressing embedding will not be used. There are generally no problems with cutting and inlaying, mainly in the control of grinding and polishing processes, which is crucial to the quality of sample preparation. High quality samples can truly reflect their organizational structure information, provide accurate data for the overall analysis of the components, and make more accurate judgments.

    After repeated practice, QMAXIS sample preparation experts have summarized the four step preparation method for metallographic samples of TSC and TBC metal anti-corrosion coatings, and shared it with friends for reference.

Microscopic photos of the coating at a magnification of 180x in a bright field

    Based on practical preparation experience, the four step TSC and TBC metal anti-corrosion coating sample preparation procedures have been summarized, as follows:

    Attention: When using diamond polishing suspension, it should not be too small, otherwise it will reduce grinding efficiency and slow down the polishing process, making it difficult to remove scratches. In addition, lubricants should be used to avoid damage to the surface of the sample due to insufficient lubrication and heat generation; And the loading force should also be controlled appropriately.

    The above four step preparation method is a commonly used method in our laboratory, and there are many other methods. Depending on the composition of the coating, the testing purpose, and personal preparation experience and habits, there may be differences. If you need detailed information or have any difficult questions that require the support of QMAXIS application engineers, please feel free to contact us. You are also welcome to personally experience QMAXIS metallographic equipment and QMAXIS metallographic consumables in QMAXIS's laboratory.