Band 115, Heft 5

A low- T g SnO–MgO–P 2 O 5 (SMP) glass was mixed with polytetrafluoroethylene (PTFE) to form composites by a sintering route. Effects of SMP:PTFE ratio and sintering temperature (350 °C–430 °C) on the microstructure and the bonding ability to a low thermal-expansion glass substrate were investigated. The onset softening temperatures of SMP and PTFE are close (328 °C and 313 °C), which are much lower than the onset temperature of weight loss of PTFE (381 °C). This is important for the sintering of SMP–PTFE composites. After sintering, pure SMP glass was not able to bond to the low thermal-expansion 1737 ® glass substrates. However, SMP–PTFE composites were able to bond to 1737 ® after sintering at appropriate temperatures. A possible mechanism for the enhancement of bonding by adding PTFE is discussed.

This work investigates the possibility of using recycled glass fibre (rGF) to co-process porous geopolymer. A new procedure was developed to incorporate rGF into geopolymer preparation and the content of rGF in porous geopolymer was varied to investigate its effect on thermal and mechanical properties. The rGF was co-processed through mixing with a combination of sodium hydroxide (NaOH) and sodium silicate (Na 2 SiO 3 ) solution to supplement raw materials required to make geopolymer but also provide fibres as potential structure reinforcement. Due to the enriched silica content obtained from rGF and leftover fibres, a nearly 80 % strength increase (from 0.092 MPa to 0.165 MPa) was obtained without compromising its low thermal conductivity. This opens up a potential route to re-using rGF in the development of improved porous geopolymer for thermal insulation applications.

In this paper, a low elastic modulus, non-cytotoxic Ti-10Ta-2Nb-2Zr titanium alloy was prepared by selective laser melting additive manufacturing. The effect of annealing and solution heat treatment on the structure, mechanical properties, and tribological behavior were investigated. The results show that the microstructure was composed of the main α′ phase and a small amount of β phase. Heat treatment improved strength and elongation. The ultimate tensile strength ( UTS ) and elongation of the deposited specimen were 807 ± 8.74 MPa and 6.6 ± 0.75 %, respectively. After annealing, the UTS was nearly the same, but the elongation increased to 15.3 ± 0.95 %. After solution and aging, the UTS and elongation increased to 873 ∼ 813 MPa and 9.25–11.9 %, respectively. The elastic modulus of the deposited specimen was 120 ± 6.81 GPa. The elastic moduli of heat treated specimens ranged from 74 ± 4.04 to 96 ± 5.13 GPa. The elastic moduli of heat treated specimens were close to that of β-type titanium alloys. The wear mechanism was mainly abrasive wear and oxidative wear. Compared with the deposited and annealed specimens, the solution and age treated specimens had low friction coefficients and much better wear resistance. In terms of properties and cost, the designed alloy has great potential in the medical implant field.

In the present research, uncoated and coated (CrN/SiN–CrN) granite dust reinforced aluminum alloy (AA 1050, AA 5083) composites samples were fabricated using stir casting and their physical, mechanical and slurry erosion behavior were assessed. The study reveal a persistent increase in void content, hardness, impact strength and stress intensity factor for both uncoated and coated alloy with the inclusion of reinforcement. In contrast, flexural strength and corrosion rate decrease continuously with increased granite content and also with the corresponding coating. Multilayer coated 5083 aluminum alloy composite with 6 wt.% granite particle shows maximum hardness, impact strength and stress intensity factor and minimum slurry erosion rate. The entropy method was applied to the operating parameter to rank the fabricated composites. The performance of each operating parameter is determined using the VIKOR (Vise Kriterijumska Optimizacija Kompromisno Resenje) optimization method. The optimal formulation based on Performance-Defining Attributes (PDAs) is observed for multilayer-coated 6 wt.% granite particulate reinforced 5083 aluminum alloy composites.

This paper describes the synthesis of Ag 2 ZrO 3 nanocrystals using coprecipitation and microwave-assisted hydrothermal methods. These nanocrystals were characterized by means of X-ray diffraction, micro-Raman spectroscopy, Fourier transform infrared absorption spectroscopy, field emission scanning electron microscopy, and UV–Visible spectroscopy, and their photocatalytic performance for methylene blue degradation under visible-light irradiation has been tested. The X-ray diffraction, micro-Raman spectroscopy, Fourier transform infrared absorption spectroscopy analyses indicate that the Ag 2 ZrO 3 nanocrystals have good crystallinity and no secondary phases. The UV–Visible spectroscopy results showed a variation in the optical band gap values (2.71–2.97 eV) with increasing temperature, which indicates the possible presence of defects in the crystal lattice at a medium range. Field emission scanning electron microscopy images revealed that the nanocrystals have uneven spherical shapes and average particle size around 50–70 nm. The good photocatalytic efficiency can be attributed to defects in the silver zirconate structure capable of forming the active adsorption sites. Finally, we discuss a photocatalytic mechanism to understand the photocatalytic process in cationic dye (methylene blue) degradation in aqueous solution.