In the relentless pursuit of advancing industrial processes, a team of researchers led by Dr. Gao Yuan from the School of Metallurgical Engineering at Xi’an University of Architecture and Technology has made a significant breakthrough in high-temperature lubrication technology. Their work, published in *Cailiao gongcheng* (which translates to *Materials Engineering*), focuses on the development of a novel PVA-modified silicate-based glass composite lubricating coating, promising to revolutionize the hot extrusion of challenging metals like zirconium, titanium, and hafnium.
Hot extrusion, a critical process in the production of zirconium alloy tubes, rods, and profiles, has long been plagued by issues of adhesion and poor lubrication. These challenges not only compromise machining accuracy but also significantly reduce mold life, leading to increased costs and downtime. Dr. Gao Yuan and his team have tackled this problem head-on by incorporating low melting point borate glass and two-dimensional layered lubricants such as MoS2 and graphite into a PVA-modified silicate coating. This innovative approach aims to enhance wetting properties and high-temperature wear resistance, thereby improving the overall efficiency and longevity of the extrusion process.
The research delves into the high-temperature physical and chemical properties of the materials, utilizing thermogravimetric analysis and differential scanning calorimetry. X-ray photoelectron spectroscopy and Fourier infrared spectroscopy were employed to analyze the functional groups and chemical bonds of the PVA-modified binders. The adhesion of the coating was tested using a cross-cut test, while an X-ray diffractometer was used to examine phase changes at high temperatures. The lubrication performance was characterized through a high-temperature friction testing machine, and post-friction analysis was conducted using optical microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy.
The results are nothing short of impressive. After PVA modification, the contact angle between the lubricant slurry and the zirconium alloy surface decreased from 64° to 43°, significantly improving the spreadability of the lubricant. Additionally, the microhardness of the lubricating coating increased from 92HV0.1 to 149HV0.1, and the dropout rate plummeted from 42.5% to 9.1%, indicating a substantial enhancement in mechanical properties. Dr. Gao Yuan explained, “The C—O—Si bonds formed by PVA and silicates create an inorganic silicon network structure in the coating, which plays a crucial role in isolating air and preventing oxidation.”
High-temperature oxidation experiments conducted at 700°C revealed that the PVA-modified silicate lubrication coating retained a certain amount of MoS2, unlike the unmodified coating, which showed almost no molybdenum disulfide and even oxidation of the zirconium alloy substrate. This underscores the superior oxidation resistance of the modified coating. In friction experiments, the prepared coating demonstrated effective lubrication at 700°C, attributed to the molten glass powder’s inherent lubricating ability at high temperatures, coupled with the unoxidized two-dimensional layered lubrication materials, MoS2 and graphite.
The implications of this research are far-reaching, particularly for the energy sector, where the production of zirconium and other refractory metals is crucial. Improved lubrication and oxidation resistance can lead to more efficient and cost-effective manufacturing processes, ultimately benefiting industries such as nuclear energy, aerospace, and chemical processing. Dr. Gao Yuan’s work not only addresses current challenges but also paves the way for future advancements in high-temperature lubrication technology.
As the world continues to demand more from its materials and processes, innovations like these are essential. The research published in *Cailiao gongcheng* offers a glimpse into a future where the extrusion of difficult-to-process metals is more efficient, sustainable, and economically viable. With further development and application, this technology could set new standards in the field, driving progress and shaping the future of industrial manufacturing.