Evaluation of the accuracy indicators in determination of the coating thickness by crater grinding method

Thickness is one of the key indicators characterizing the quality and functional properties of coatings. Various indirect methods (electromagnetic, radiation, optical) most often used in practice to measure thickness are based on the functional dependence of a particular physical parameter of the system «base – coating» on the coating thickness. The sensitivity of these procedures to the certain properties of coatings imposes the main restriction to the accuracy of measurements. Therefore, the development and implementation of the approaches based on direct measurements of geometric parameters of the coating appears expedient. These methods often belong to the class of «destructive» and, in addition to measuring instruments, require the use of special equipment. To ensure the uniformity of measurements in the laboratory or technological control, these methods are isolated as a separate procedure (method) and must undergo metrological certification in accordance with GOST R 8.563–2009. We present implementation, metrological certification and practical application of the method for measuring thickness of coatings by crater-grinding method. The principles of technical implementation of test equipment, measurement procedure and calculation formulas are described. The results of evaluating the accuracy indicators of the proposed procedure by calculation and experimental methods are presented. In both cases, the relative error did not exceed 6%. The applicability of the developed technique is shown for a wide range of coating materials (from soft metals to superhard ceramics) of different thickness (with from units to hundreds of micrometers). Apart from the goals of process control and outgoing inspection, the method can be recommended as a reference measurement procedure for calibration of measures and adjusting samples for various types of thickness gauges.

1. Golubev S. S., Babadzhanov L. S., Babadzhanova M. L. The Structure and Content of Metrological Assurance of Assessing the Conformity of Indicators upon Quality Control of Coatings. / Zavod. Lab. Diagn. Mater. 2017. Vol. 83. N 4. P. 71 – 74 [in Russian].

2. Golubev S. S., Babadzhano L. S., Gogolinsky K. V., Syasko V. A. Actual problems of metrological assurance of quality control of coatings / Zakonodat. Prikl. Metrol. 2017. Vol. 146. N 1. P. 19 – 23 [in Russian].

3. Babadzhanov L. S., Babadzhanova M. L. Metrological support for coating thickness measurements. Theory and practice. — Moscow: Izd. Standartov, 2004. — 264 p. [in Russian].

4. Potapov A. I., Syasko V. A. Non-destructive methods and means of controlling the thickness of coatings and products. — St. Petersburg: Gumanistika, 2009. — 1100 p. [in Russian].

5. Golubev S. S., Syasko V. A., Smirnova N. I., Gogolinsky K. V. Phase-sensitive eddy-current method of metallic coating thickness measurement. On question of calibration and verification of coating thickness gauges and metallic coating thickness standards / Proc. 55th Annual Conf. of Non-Destructive Testing (NDT). — Nottingham, UK, 2016. P. 166 – 174.

6. Golubev S. S., Smirnova N. I., Skladanovskaya M. I. Providing the Uniformity of Measurements of the Thickness of Metallic Coatings by Eddy-Current Phase Thickness Gages During Their Calibration and Verification / Measurement Techniques. 2017. Vol. 60. N 6. P. 552 – 557. DOI: 10.1007/s11018- 017-1233-0.

7. Syasko, V. A., Golubev, S. S., Smorodinsky Ya. G., et al. Measurement of Electromagnetic Parameters of Metal-Coating Thickness Measures / Russ. J. Nondestruct Test. 2018. Vol. 54. P. 698 – 710. DOI: 10.1134/S1061830918100091.

8. Useinov A. S., Gogolinsky K. V., Reshetov V. N. Measurement of the mechanical properties of superhard diamond-like carbon coatings / Izv. Vuzov. Ser. Khimiya Khim. Tekhnol. 2011. Vol. 54. N 7. P. 51 – 54 [in Russian].

9. Quinones-Salinas M. A., Mercado-Solis R. D. Comparative study of three methods for measuring thickness of PVD hard coatings / International Journal of Surface Science and Engineering. 2015. Vol. 9. N 6. P. 493 – 509. DOI: 10.1504/ IJSURFSE.2015.072831.

10. Bomparola R., Caporali S., Lavacchi A., Bardi U. Silver electrodeposition from air and water-stable ionic liquid: An environmentally friendly alternative to cyanide baths / Surface and Coatings Technology. 2007. Vol. 201. Issue 24. P. 9485 – 9490. DOI: 10.1016/j. surfcoat. 2007. 04. 008

11. Černý F., Pitter J., Konvičková S., Jech V. High temperature oxidation protective chromium-based coatings prepared by IBAD and PACVD methods / Surface and Coatings Technology. 2009. Vol. 203. P. 2566 – 2570. DOI: 10.1016/j.measurement. 2014.06.002

12. Corbella C., Rubio-Roy M., Bertran E., et al. Low friction and protective diamond-like carbon coatings deposited by asymmetric bipolar pulsed plasma / Diamond & Related Materials. 2009. N 18. P. 1035 – 1038. DOI: 10.1016/j.diamond.2009. 01.003

13. Körber F.-J. The role of ion implantation in industrial sputtering processes for tribological applications / Surface and Coatings Technology. 1995. Vol. 74 – 75. P. 168 – 172. DOI: 10.1016/ 0257-8972(95)08362-6.

14. Rutherford K. L., Hutchings I. M. A micro-abrasive wear test, with particular application to coated systems / Surface and Coatings Technology. 1996. Vol. 79. Issue 1 – 3. P. 231 – 239. DOI: 10.1016/0257-8972(95)02461-1.

15. Ramazanov A. K., Ganeev A. A. Conditions and requirements for materials of pipe fittings refining industry / Oil and Gas Business. 2015. N 4. P. 313 – 325. DOI: 10.17122/ogbus- 2015-4-313-325 [in Russian].