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Purpose: This paper aims to analyze the characteristics of friction vibration signals and identify the vibration excitation source at the start and stop stage of microtextured end face of dry gas seals. Design/methodology/approach: The friction pair consists of a diamond-like carbon (DLC) film microtextured seal ring and a spiral groove seal ring. Friction vibration signal feature extraction method based on harmonic wavelet packet and spectrum analysis was proposed. Signals were collected using acceleration sensor, acquisition card and LabVIEW software. Vibration acceleration signal was decomposed into 32 frequency bands using MATLAB wavelet packet transformation. The 32nd band coefficient was extracted for reconstruction, time-domain and spectral waveforms were obtained and spectra before/after denoising were compared. Findings: The end face of the DLC film microtextured seal ring generates a good dynamic pressure effect, and the friction and vibration reduction effects are obvious. The harmonic wavelet packet can decompose the vibration signal conveniently and precisely. In the case of this experiment, the frequency of vibration of the seal ring is 7500 HZ. Originality/value: The results show that the method is effective for the processing of friction vibration signal and the identification of vibration excitation source. The findings will provide ideas for the frictional vibration signal processing and basis for further research in the field of tribology of dry gas seal ring. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2024-0084/ [ABSTRACT FROM AUTHOR]

Purpose: This study aims to research the influence mechanism of microtextured geometric parameters of dry gas seal end face on the tribological behavior under dry frictional conditions. Design/methodology/approach: The microtexture was processed using laser processing, while the diamond-like carbon (DLC) film was applied through magnetron sputtering; the experimental platform of friction vibration was established, the frictional and vibrational properties of different geometric parameters were tested; the data signals of vibrational acceleration and frictional torque were collected and processed using data acquisition instrument. The entropy characteristic parameters of 3D vibrational acceleration were extracted based on wavelet packet decomposition method. The end-face topography was measured with ST400 three-dimensional noncontact surface topography instrument. Findings: The geometry of pits plays a key role in influencing friction performance; the permutation entropy and fuzzy entropy of the vibration acceleration signal changed with variations in microtextured parameters. A textured surface with appropriately size parameters can trap debris, enhance the dynamic pressure effect, reduce impact between the friction interfaces and improve the frictional vibrational performance. In this research, microtextured surface with Φ150 µm-10% and Φ200 µm-5% can effectively reduce friction and vibration between the end faces of a dry gas seal. Originality/value: DLC film improves the hardness of seal ring end face, and microtexture improves the dynamic effect; the tribological behavior monitoring can be realized by analyzing the characteristics of vibration acceleration sensitive parameter with friction state. The findings will provide a basis for further research in the field of tribology and the microtexture optimization of dry gas seal ring end face. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2023-0389/ [ABSTRACT FROM AUTHOR]

In this study, the frictional properties of dry gas seal rings with a diamond-like carbon (DLC) film textured surface were investigated using a vertical universal friction and wear tester. The ensemble empirical mode decomposition (EEMD) method was applied to extract friction and vibration signals. In combination with chaos theory, analyses of the friction and wear of dry gas seal rings were performed under specific working conditions. The results show that the variation in friction vibration attractors and phase-point average distance is consistent with the change in the friction coefficient. The DLC film textured surface effectively improves the frictional properties of dry gas seals. The edges of the microtextured pits can cut debris, so the diameter of the debris becomes increasingly smaller. At the same time, the microtextured pits can also capture wear debris. The optimized dimple diameter and area density were 250 μm and 15%, respectively. In this case, the texture pit can catch almost all of the debris, but the friction vibration was not severe. [ABSTRACT FROM AUTHOR]

The frictional vibration performances of textured surface coated with DLC(Diamond-like Carbon)film of dry gas seals ring were investigated. In the meantime, the mechanism of textured surface on interfacial tribological behavior was revealed under dry frictional condition. The acceleration and frictional force were measured by using universal friction and wear tester which type is MMW-1, and the surface topographies were measured by using SEM and ST400 three-dimensional non-contact surface topography instrument. Results show that the textured surface coated with DLC film can significantly improve the tribological behavior of dry gas seal. Textured surface with reasonable size parameters can capture debris and avoid strong impact between the friction pairs, which improves effectively the tribological behavior of interfaces. • The frictional vibration performance of the DLC film textured surface has been researched, the mechanism of tribological behavior has been revealed in this paper. • The effects of the varied geometric parameters of the textured surface on the signal variation of the friction and acceleration of vibration on the interface are investigated, and corresponding regularity has been identified. • The findings of this research provide the foundation for the tribological study of the end face of dry gas seals and optimization of the micro texture structure. [ABSTRACT FROM AUTHOR]