Hydraulic technology has been instrumental in the extensive application of offshore mechanical equipment, particularly in drilling platforms and ships, where high-performance hydraulic fluids are essential for safe and efficient operations. Addressing the urgent need for water-based hydraulic fluids as an alternative to traditional oil-based fluids, this study introduces a novel water-based hydraulic fluid fortified with phytic acid, derived from plant seeds, to achieve low biotoxicity, low coefficient of friction, and reduced frictional heat generation. The integration of phytic acid has significantly enhanced the lubricating performance, reducing the average coefficient of friction to as low as 0.013, as tested by the four-ball tester, which is the lowest value reported to date. Real-time monitoring of the temperature rise of the friction testing apparatus using an infrared thermal imager revealed a 78.6% reduction in temperature increase. Acute toxicity assays using Brine Shrimp demonstrated that the 96 h LC50 value for the water–glycol flame-resistant hydraulic fluid with added phytic acid exceeded 26,304 mg/L, indicating low toxicity. Characterization analyses elucidated the mechanisms underlying the improved tribological properties, highlighting the potential of this eco-friendly fluid for safe and efficient offshore operations.
With the development of deep-sea exploration technology, the technology of fire-retardant hydraulic fluid (HFC) has played an important role in the power transmission of exploration equipment. However, the mechanism of the influence of seawater content on the tribocorrosion behavior of HFC remains unclear. In this study, the effects of different seawater contents on the tribological and corrosive properties of HFC were systematically investigated. The results showed that when the seawater concentration exceeds 30 wt%, a soft Mg-containing reaction film is formed in the friction contact area owing to seawater corrosion, thus effectively improving the sintering load and wear resistance to some extent. By contrast, with increasing seawater concentration, the lubricity declines, the wear intensifies, and the extreme pressure characteristics decrease significantly. The comparative analysis shows that the composition of the wear and corrosion reaction films significantly differs under high-concentration seawater conditions, which is also a key factor affecting the friction and corrosion behavior of HFC. This study provides a direction for the research and development of wear- and corrosion-resistant materials and coatings on the surface of deep-sea exploration equipment.