In this paper ∼16 μm-emitting multimode InP-related quantum cascade lasers are presented with the maximum operating temperature 373 K, peak and average optical power equal to 720 mW and 4.8 mW at 303 K, respectively, and the characteristic temperature (T₀) 272 K. Two types of the lasers were fabricated and characterized: the lasers with a SiO₂ layer left untouched in the area of the metal-free window on top of the ridge, and the lasers with the SiO₂ layer removed from the metal-free window area. Dual-wavelength operation was obtained, at λ ∼ 15.6 μm (641 cm⁻¹) and at λ ∼ 16.6 μm (602 cm⁻¹) for lasers with SiO₂ removed, while within the emission spectrum of the lasers with SiO₂ left untouched only the former lasing peak was present. The parameters of these devices like threshold current, optical power and emission wavelength are compared. Lasers without the SiO₂ layer showed ∼15% lower threshold current than these ones with the SiO₂ layer. The optical powers for lasers without SiO₂ layer were almost twice higher than for the lasers with the SiO₂ layer on the top of the ridge.

Surface phenomena play a major role in metallurgical processes; their operation results, among others, from the surface tension of liquid oxidic systems. One of the methods of determining surface tension of oxidic systems is performing calculations with Butler’s method. Surface tension was calculated for two- and three-component liquid oxidic systems typical of metallurgical processes. The determined dependence of surface tension in FeO-SiO2 at temp. 1773 K and CaO-SiO2 at temp.1873 K showed that with the growing participation of SiO2 surface tension decreased. Analogous calculations were performed for three-component systems: CaO-Al2O3-SiO2 and MnO-Al2O3- SiO2. The results of calculations of surface tension were determined for temp. 1873 K and compared with the results obtained by T. Tanaka et al. [19]. In both cases the increase of Al2O3 content resulted in a growth of surface tension. The simulation results were higher than experimental result, as compared to the literature data.

Silicate coatings have been considered as an alternative to toxic and carcinogenic other chemical treatments. In this paper, a strengthened silicate coating was formed on the surface of low carbon steel by dip immersion method. The modification and strengthening was done by loading colloidal nano-SiO2 into the film. The characterizations of nano-SiO2 were investigated by FESEM, TEM and FT-IR. The effects of nano contents (weight ratio) and drying temperatures on corrosion properties of silicate film were studied. Potentiodynamic polarization, electrochemical impedance spectroscopy and immersion tests have been used to study corrosion behavior of nano-loaded silicate films. Surface morphology, microstructure and its chemical composition were analyzed by means of FESEM, EDS, AFM, XRD, GIXRD, ATR-FTIR and Raman techniques. Results indicated that colloidal nano-SiO2 properly modified the silicate coatings and significantly improved the corrosion resistance and barrier property. Also drying temperature showed a considerable effect in silicate coating and higher corrosion resistance was obtained with 150°C curing.

The mechanical properties of cement paste modified by nano-TiO2 (nT) and nano-SiO2 (nS) were experimentally studied. The compressive strength increased first and then decreased with the increase of nanoparticle content. When nanoparticles were added into the cement paste as a filler to improve the microstructure, the two kinds of particles both could form a tighter mesh structure, which would enhance the density and strength of the structure. The elastic modulus increased rapidly with the increase of the nT content and reached a peak when the nanoparticle content is about 3%, which was about twice the elastic modulus of ordinary cement paste. The Scanning electron microscopy (SEM) observation results showed that the microstructure of cement was network connection and fiber tube. The hydration progress of ordinary cement slurry was insufficient, and many unreacted cement particles remained. With the addition of nanoparticles, the internal structure of the cement became denser, with fewer pore cracks, smaller pore diameters, more complex fiber tube arrangements, and significant anisotropy, thereby improving strength and mechanical properties.