Optimization of depositing uniform and wear-resistant diamond films on massive mechanical seals

Abstract

Purpose This study aims to obtain diamond-coated mechanical seals with improved sealing performance and considerable cost. To achieve this purpose, the study focuses on depositing uniform, wear-resistant and easily polished diamond coatings on massive mechanical seals in a large-scale vacuum chamber. Design/methodology/approach The computational fluid dynamics simulation test and its corresponding deposition experiment are carried out to improve the uniformity of diamond films on massive mechanical seals. The polishing properties and sealing performance of mechanical seals coated with three different diamond films (microcrystalline diamond [MCD], nanocrystalline diamond [NCD] and microcrystalline/nanocrystalline diamond [MNCD]) and uncoated mechanical seals are comparatively studied using the polishing tests and dynamic seal tests to obtain the optimized diamond coating type on the mechanical seals. Findings The substrate rotation and four gas outlets distribution are helpful for depositing uniform diamond coatings on massive mechanical seals. The MNCD-coated mechanical seal shows the advantages of high polishing efficiency in the initial polishing process and excellent wear resistance and self-lubrication property in the follow-up polishing period because of its unique composite diamond film structures. The MNCD-coated mechanical seal shows the longest working life under dry friction condition, about 14, 1.27 and 1.9 times of that for the uncoated, MCD and NCD coated mechanical seals, respectively. Originality/value The effect of substrate rotation and gas outlets distribution on temperature and gas flow field during diamond deposition procedure is simulated. The MNCD-coated mechanical seal exhibits a superior sealing performance compared with the MCD-coated, NCD-coated and uncoated mechanical seals, which is helpful for decreasing the operating system shut-down frequency and saving operating energy consumption.

Influence of contact form on mechanical wear characteristics of single diamond scratching on Ta12W

“…As abrasive tools are fabricated by plenty of SCD grits, the mechanical wear of abrasive machining is extremely complex (He et al, 2018). Thus, single SCD grit scratching process is a significant and effective method to investigate the complex mechanical wear mechanism of abrasive precision machining and ultra-precision machining process Wang, et al, 2018).…”

Improving Pressure–Velocity Limit of Mechanical Seal with Polycrystalline Diamond Coating

“…Thus, a mechanical seal face designed in combination with a polycrystalline diamond (PCD) coating could offer an outstanding abrasion resistance and, at the same time, a considerably improved performance under poor lubrication conditions like in high-viscosity fluids and even in dry-running condition due to the low friction coefficient. Numerous studies have confirmed that the diamond coatings considerably lower the friction and enhance the tribological performance in mechanical face seals [2,[4][5][6][7][8][9][10][11][12][13][14]. However, there are few researches on the upper limit of mechanical seals with PCD coating application under conditions where the combination of high pressure and high surface speeds create high levels of pressure-velocity (PV).…”