Silica nanospheres with a well-controlled particle size were prepared via a nucleation-to-growth synthesis process. A facile method is proposed for improving the self-assembly behavior of silica colloidal particles in droplet coatings by the simple controlling of the drying temperature. It is shown that a periodically arranged, opal-structured, photonic crystal film with a large area of approximately 4.0 cm2 can be prepared, even when the particle size is up to 840 nm. When the band gap of the silica photonic crystals falls in the visible-light region, the crystals exhibit distinct structural colors. Moreover, the wavelength of the reflected light increases with an increasing particle size of silica. When the photonic band gap overlaps the wavelength of the laser source, the overall Raman spectrum intensity is significantly enhanced. Accordingly, the proposed nucleation-to-growth process and drop-coating method provides a cheap and simple approach for the manufacture of uniform sized silica and surface-enhanced Raman scattering substrates, respectively.

In recent years, the application of low-refractiveindex materials in the optical field has attracted considerable attention due to it high transmittance and high optical sensitivity. In this study, we synthesized SiO 2 porous hollow spheres (SPHS) with an ultralow refractive index (n = 1.05) by using a templating method. Their refractive indices could be easily controlled from 1.05 to 1.08 by tuning the thickness of shell. In addition, a droplet coatings method is proposed for SPHS colloidal crystal (CC) by controlling the temperature and humidity. The SPHS CCs displayed distinct structural colors when the incident angle was adjusted and demonstrated high angular resolution. Moreover, the iridescent color changes could be observed with the naked eye. For surface-enhanced Raman scattering application, more analyte could be absorbed by the porous shells, and metal nanoparticles were coated on the SPHSs surface to increase the hot spot density for improving the SERS intensity.

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Acid Ni-P and alkaline Ni-P coatings were prepared on 30CrMnSi alloy steel by electroless plating method. 3 pH values were selected for each type. The phosphorus content, hardness and wear resistance coefficient of the 6 kinds of coatings were tested. Experimental results showed that the mass fraction of P was less than 4% range, with the increase of P content, the hardness and wear resistance of two kinds of coating had been improved, the hardness and wear resistance of acid coating were better than that of alkali coating.

In this study, we provided a designed TiO 2 coating and hydrothermal treatment to synthesize nano-sized TiO 2 /SiO 2 cenospheres (TSCSs) with a rough surface for the application in the solar thermal reflective coating. Various functions of the TSCSs are present, the chemical composition causing significant UVA absorption, hollow interiors have high reflectance of the visible-IR radiation, and strong scattering of incident light. In addition, the low thermal conductivity of TiO 2 , SiO 2 , and the hollow interiors makes the coatings of TSCSs achieve a good thermal insulation. The average infrared reflectance of this coating is 89.61%, and the UVA transmission is only about 22.81%.In addition, the coatings of TSCSs also demonstrate good water resistance on the glass slide due to the closure shell and rough surface to prevent water from entering the pore and cavity.