Insufficient yield stress and electrorheological (ER) efficiency have already become the limitations for the practical application of ER fluids. Herein, we report a simple and scalable co-precipitation method for synthesizing surfactant-modified calcium titanyl oxalate (SCTO) particles with a rod-like structure. The obtained SCTO materials not only present a yield stress twice as that of granular CTO ER fluids but also demonstrate low zero-field viscosity, which results in a high ER efficiency. In terms of microstructure and dielectric analysis, we infer that the exceptional ER activity is in large part due the anisotropic morphology and improved wettability of the rod-like SCTO. This work provides the basis for the future development of ER fluids and the promotion of their practical application.

Materials with very low refractive index are essential to prepare broadband graded-index antireflection (AR) coatings. However, the availability of such materials is very limited. In this study, large-area ($4\mathrm{cm}\times 4\mathrm{cm}$) low refractive index porous anodic alumina (PAA) coatings on glass substrate were prepared successfully by electron-beam evaporation, electrochemical oxidation, and chemical etching method. The nanopore size of PAA film is smaller than 40 nm, and the refractive index of PAA film is $n=1.08$. Besides, five-layered graded-index broadband PAA coatings with refractive indices following the Gaussian profile were also prepared to noticeably eliminate the reflectance of glass over a broadband wavelength, and the lowest reflectivity is 0.64% at the wavelength of 534 nm at normal incidence. The PAA AR coatings having an omnidirectional nature are likely to have practical applications in photovoltaic cells and optical devices.

TiO_x-based nanospheres modified by formamide (FA) as dielectric particles for electrorheological (ER) fluids were successfully synthesized through simple sol–gel hydrolysis and self-assembly. The suspension containing TiO_x–FA displays superior ER activity, with a yield stress of 148 kPa (at 5 kV mm⁻¹) under a DC electric field, which is 10 times that of ER fluids containing pure TiO_x nanoparticles. More importantly, comparison between the FA and N,N-dimethylformamide (DMF) as the shell structure indicated that the ER performance was positively correlated with the dielectric constant of the polar molecule shell. The result represents a critical step towards an in depth understanding the enhancement effect of polar molecules. This study can afford a new strategy to achieve optimal performance in ER fluids.

As an effective technique for fabricating conductive and thermally conductive polymer composites, a multi-filler system incorporates different types and sizes of multiple fillers to form interconnected networks with improved electrical, thermal, and processing properties. In this study, DIW forming of bifunctional composites was achieved by controlling the temperature of the printing platform. The study was based on enhancing the thermal and electrical transport properties of hybrid ternary polymer nanocomposites with multi-walled carbon nanotubes (MWCNTs) and graphene nanoplates (GNPs). With thermoplastic polyurethane (TPU) used as the matrix, the addition of MWCNTs, GNPs and both mixtures further improved the thermal conductivity of the elastomers. By adjusting the weight fraction of the functional fillers (MWCNTs and GNPs), the thermal and electrical properties were gradually explored. Here, the thermal conductivity of the polymer composites increased nearly sevenfold (from 0.36 W·m⁻¹·k⁻¹ to 2.87 W·m⁻¹·k⁻¹) and the electrical conductivity increased up to 5.49 × 10⁻² S·m⁻¹. It is expected to be used in the field of electronic packaging and environmental thermal dissipation, especially for modern electronic industrial equipment.

In order to improve the wear properties of FeCoCrNi high entropy alloy (HEA), laser cladding was applied to fabricate FeCoCrNiAl_x HEA coatings with different Al additions. The Al-modified coatings exhibited excellent metallurgical bonding interfaces with the substrates. The microstructure of FeCoCrNiAl_0.5 coating was the same as of the FeCoCrNi coating: face-centered cubic (FCC). However, the microstructure of FeCoCrNiAl was different: body-centered cubic (BCC) with more Al atoms distributed inside the grains. As the Al content in the coating was increased, the hardness increased as well from 202 to 546 HV_0.2, while CoF and wear rate decreased from 0.62 to 0.1 and from 8.55 × 10⁻⁷ to 8.24 × 10⁻⁹ mm³/(Nm), respectively. The wear mechanisms changed from the mixture of abrasive, adhesive, and oxidative wear patterns to the mixture of abrasive and oxidative patterns. Such a change indicates that the Al addition indeed improved the wear resistance of FeCoCrNiAl_x HEA coatings. Our results expand knowledge on HEA coating applications as wear-resistant materials in various applied industrial fields.

In this letter, we provide a phenomenological model to explain the recently discovered volume fraction effect in giant electrorheological (ER) fluids. We attribute the exponential dependence of yield stress on volume fraction to the repulsive interaction between particle chains. The increase of particle concentration increases the inter-chain repulsive interaction, which raises potential energy in electrorheological fluid and consequently the yield stress. The acquired normal force data validated our model.