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Gamma aluminum oxynitride (γ-AlON) with a cubic spinel structure is a stable solid solution of Al 2 O 3 -AlN system, which has been attracted much attention in recent decades. 1,2 Transparency of AlON fully dense specimen is in the wavelength range of about 0.2-5 μm. 3 AlON is appropriate for phosphor-converted white LED, light-emitting devices, load-bearing orthopedic, and ceramic semiconductors because of its excellent optical properties besides high hardness and strength. AlON can be used instead of sapphire with a lower price, for applications that excellent mechanical and optical properties are needed. [4][5][6] Carbothermal reduction and nitridation (CRN) method is the most applied technique for AlON fabrication comparing to the other methods. The first report of using the CRN method was published by Yamaguchi et al. in 1959. 6,7 This method needs simple equipment, cheaper raw materials compared to the solid phase reaction, and the final product of this technique has a uniform chemical composition in terms of stoichiometry. 6,8 Remained carbon content in the final product and various effective factors, which can hardly be controlled, are disadvantages of this method. When the CRN method uses as a single-step process, before producing enough amounts of AlN beside α-Al 2 O 3 , a large part of the AlO 2 gaseous species exists because of the high temperature (more than 1800°C) of synthesis. This results in an excessive reduction of Al 2 O 3 phase amount, and consequently, the AlN phase presents in the final product. 9,10 The main reaction of twostep CRN technique corresponds to reaction (1):This main reaction consists of two sub-reactions, which in the first step, γ-Al 2 O 3 reacts with carbon and nitrogen; accordingly, AlN is produced. In the second step, α-Al 2 O 3 reacts with AlN and AlON is fabricated as the final product. 6,11 (1) 64 + x 3 Al 2 O 3 + 3xC + xN 2 → 2Al 64+x 3 O 32−x N x + 3xCO

In this research, the microstructure and optical behaviour of a novel Al 2 O 3 -Ag composite coating have been investigated. The composite films were synthesised by the addition of silver nanoparticles into the anodizing electrolyte solution with the concentration of 100-1500 mg per 600 mL. SEM, EDS, XRD and Raman tests were employed to study the microstructure of the coatings. The optical properties were also characterized by FTIR and UV-Vis experiments. The results showed that the average pore diameter was increased by the co-deposition of silver nanoparticles into the alumina matrix from about 11 to 41 nm. Furthermore, silver nanoparticles could improve the optical properties of the anodic film, whereas the composite coating showed the higher absorption and emission associated with the ratio of α/ε ∼ 1.

The black coatings were fabricated via electroless NiP deposits on Ti-6Al-4V alloy substrate with heat-treatment and blackening process. Two types of coatings were obtained: coatings with heat-treatment after blackening and coatings with blackening after haet-treatment. After parameter optimization, the temperature and pH of the solution were adjusted to 85 °C–95 °C and 4.3–4.7, respectively. The substrate was coated after the addition of modifying components to the solution. After refluxing the samples, the blackening process was done for 40 s in nitric acid (9molar). An SEM-EDS analyze used to assess the morphology and chemical composition of the coating. Moreover, adhesion strength and optical absorptance of the coating were measured by Pull Of test and Shimadzu UV-3100 analysis, respectively. The optical absorptance was measured by 0.89 and 0.95, respectively, for Oxalic acid and Nitric/Flouridric acid pretreated samples. Results showed that heat-treatment after blackening causes coating with higher micro-hardness and optical absorption. The blackened electroless NiP coating on Ti substrate with the heat-treatment of 4 h after the blackening process provided high solar absorption of 0.99, which is exceptionally suitable as a solar absorber coating for space and allied applications.

Aims: To evaluate the effect of multiple-use and sterilization on cyclic fatigue and shaping ability of heat-treated nickel-titanium (NiTi) rotary instruments. Methods: A total of 120 acrylic blocks with S-shaped canals were photographed and prepared by HyFlex CM, ProTaper Next, and Twisted File. Ten new sets of each rotary instruments were used for four times. The autoclaving process was repeated after each use. Pre- and post instrumentation images were superimposed. The amount of resin removal and canal transportation by each system was measured in eleven different points. Instruments were subsequently subjected to a cyclic fatigue test in a double-curved artificial canal. The means and standard deviations of the number of cycles to failure (NCF) were calculated and statistically analyzed (P < 0.05). Results: No fractures occurred during the shaping of the simulated canals. The ProTaper Next removed the greatest amount of resin, whereas the Twisted File had the lowest values at all levels. Repeated clinical use and sterilization resulted in a decrease in the resin removal at most levels in Twisted File and ProTaper Next. In terms of canal transportation, an increase in a limited number of levels was detected after repeated use of all rotary files. Twisted File had the greatest cyclic fatigue resistance, followed by HyFlex CM and ProTaper Next (P < 0.05). Conclusions: The effects of repeated use and autoclaving on the cyclic fatigue resistance of HyFlex CM, ProTaper Next, and Twisted File were not significant. Canal transportation increased mostly in the apical region. The amount of resin removal decreased as the number of use increased for ProTaper Next and Twisted File instruments.