Formation of uniform spatial distribution of Fe3O4 nanoparticles during evaporation of a magnetic nanofluid droplet on a biphilic surface

• Published in: International journal of heat and mass transfer 2025-04, Vol.239, p.126602, Article 126602
• Main Authors: Starinskaya, E.M., Rodionov, A.A., Safonov, A.I., Sulyaeva, V.S., Miskiv, N.B., Starinskiy, S.V.
• Format: Article
• Language: English
• Subjects: Biphilic surface; Cassie-Baxter; Coffee ring; Droplet evaporation; Ferrofluid; Laser ablation; Nanofluid; Nanoparticle deposit; Sessile droplet; Superhydrophilic; Superhydrophobic; Wenzel
• ISSN: 0017-9310
• DOI: 10.1016/j.ijheatmasstransfer.2024.126602

•The effect of surface wettability on nanofluid droplet evaporation was studied.•Uniform deposition of magnetic nanoparticles was achieved on the biphilic surface.•A foil effect with a dome of magnetic nanoparticles was found in late evaporation stages.•The flows inside the droplet were analyzed. This paper is dedicated to a detailed investigation of the influence of surface wettability on the evaporation dynamics of a sessile nanofluid droplet. For the first time, a comparison of the sediment formation process from magnetic nanoparticles Iron(II,III) oxide Fe3O4 on hydrophilic, hydrophobic, and biphilic surfaces, consisting of superhydrophobic and superhydrophilic areas, has been conducted. The use of biphilic surfaces allows for the uniform deposition of nanoparticles on the substrate surface when their mass concentration in liquid is low (∼0.01 wt. %). For higher concentrations (>0.1 wt. %), the formation of a solid framework during the final stages of droplet evaporation is characteristic, leading to the formation of a dome from the nanoparticles. Further liquid evaporation causes the collapse of the dome and the formation of irregular agglomerates on the substrate surface. A mechanism for dome formation is proposed, which also explains the uniform deposition of nanoparticles on the surface not observed during evaporation on hydrophilic or hydrophobic surfaces. The proposed mechanism is based on a combination of magnetic interactions between particles and the unique nature of convective flow formation during evaporation on a biphilic surface. [Display omitted]