By Cvetelin Vasilev, Ph.D.Sep 22 2022 Many industrial processes involve the heat treatment of materials, such as metals, plastics, and composites. Commonly used heat transfer fluids such as water, ethylene glycol, and oils exhibit relatively low thermal conductivity compared to solids.
The outcome of the quenching process primarily depends on the heat transfer characteristics of the quenching medium. In the context of industrial heat treatment of metal, commonly used quench fluids, such as water, brine solution, and oils, the scope for enhancing the heat transfer is very limited. Thus, material scientists in the industry and academia focus on designing quench media with enhanced heat transfer characteristics.
Importantly, a large enhancement of the thermal conductivity can be achieved at very low nanoparticle concentrations, which completely preserves the Newtonian behavior of the fluid without noticeable effects on the fluid viscosity and the required pressure drop during the fluid pumping. All these unique characteristics of the nanofluids can be exploited in the industrial heat treatment of materials.
The microstructure and hardness of the steel specimen showed significant dependence on the nanoparticle volume fraction in the nanofluid. Compared to oil quenchant, quenching in oil-based nanofluid with 0.2 vol% nanoparticle content resulted in a higher hardness of the specimen. Higher nanoparticle concentrations resulted in lower steel hardness, probably due to particle agglomeration.
Continue reading: How Nanosilver May Improve Heat Treatment Effects of Pine Wood References and Further Reading Hassoni, S. M., et al. The Role of ZnO Nano-fluids on Heat Treatments of Medium Carbon Steel. 2020 IOP Conference Series: Materials Science and Engineering. 881, p. 012095. doi.org/10.1088/1757-899X/881/1/012095