Development of the Properties and Application of Glycerol-Based Green Lubricant

Lubricants have extensive applications in various fields such as mechanical, electronic, chemical and medical industries. Traditional lubricants, mainly based on mineral oil, exhibit drawbacks including non-renewability, significant ecological impact and potential threats to human health. With the growing emphasis on energy conservation and environmental protection, renewable and environmentally friendly green lubricants have emerged as preferable alternatives to traditional lubricants. Currently, prevalent types of green lubricants encompass water-based lubricants, plant oil-based lubricants, and nano-lubricants. Notably, glycerol-based lubricants, a crucial subset of water-based lubricants, demonstrate excellent lubricating performance. This paper initiated by elucidating the friction characteristics and application domains of pure glycerol, with a particular focus on its lubrication mechanism, and reviewed the development trajectory of glycerol lubricants. It comprehensively discussed the factors influencing the tribological performance of glycerol-based lubricants and summarized the advancements taken by scientists worldwide in recent years, such as adjusting environmental humidity and water content, and introducing additives. In addition, the lubrication mechanism of glycerol-based lubricants during the friction process was meticulously analyzed. The article also provided an overview of the application of glycerol-based lubricants across various friction pairs, coatings and operating conditions, demonstrating their versatility and potential in diverse practical scenarios. This included lubrication processes in different friction conditions, such as steel/TiN, DLC films and CrN coatings. Despite showcasing considerable potential, glycerol-based lubricants encountered challenges in practical applications. The paper identified the current issues, particularly addressing the issues of poor dispersion stability, agglomeration and increased costs associated with additives. Additionally, the paper mentioned the use of acid additives to improve the lubricating performance of glycerol-based lubricants and achieve superlubricity. However, it noted that acid additives had significant environmental pollution and corrosion effects on the human body, and there were currently no green alternatives explored in this regard. Finally, the article proposed a research and technological roadmap for the development of glycerol lubrication, and discussed the potential of intelligent control in glycerol lubrication systems based on the current era of intelligence and industrialization. Specifically, it involved the use of advanced sensors, data analysis and automation control technologies to achieve real-time monitoring, optimization and intelligent control of glycerol lubrication systems. It further involved the precise adjustment of the lubricant itself and various parameters of the lubrication system based on real-time data and feedback mechanisms, thereby achieving optimal lubrication effects under different operating conditions. In conclusion, due to their renewable and environmentally friendly characteristics, glycerol-based lubricants are gradually becoming a strong alternative to traditional lubricants. This paper provided a comprehensive summary of the latest research status of glycerol-based lubricants, covering their tribological properties, application areas, improvement methods, lubrication mechanisms and challenges. By addressing these issues, researchers and industry professionals could gain valuable insights and further explored the potential of glycerol-based lubricants in various fields.