Advanced Ceramics Progress
Volume:2 Issue: 2, Spring 2016

In this paper, titanium dioxide nano-particles were synthesized by sol-gel method in acidic atmosphere. The microstructure, morphology, optical band gap, and hydrophilicity of the sample were studied. Optical band gap of titanium dioxide was probed via Diffuse Reflectance Spectra (DRS) and contact angle (CA) was measured to investigate surface activity. XRD analysis was used to study crystallinity of the samples. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) was also performed. The results presented high crystallinity of particles with average particle size of ~21nm. Very small nano-particles were obtained (as small as 7nm). The obtained optical band gap of the sample was determined which was 3.35 eV with direct linear fitness in Tauc relation. Contact angle indicated super- hydrophilicity after 40 minutes under UV-Radiation.

The main goal of this study is optimization of densification of ZrB2-SiC composites reinforced with chopped Cf prepared by SPS. Taguchi method is employed as statistical design of experiment (DOE) to optimize densification parameters including SiC, Cf, MoSi2, HfB2 and ZrC content, milling time of Cf and SPS parameters such as temperature, time and pressure. Each of these factors was examined on four levels in order to obtain the optimum conditions. A total of 32 samples were prepared in accordance to the L32 array proposed by the Taguchi method. By using statistical analysis of variance (ANOVA), it has been concluded that the most significant effect on the densification is related to temperature, MoSi2 and time by 50.2%, 20.7% and 9.8% portion, respectively. Also, the results showed that pressure with 0.8%, ZrC with 1.9% and HfB2 with 1.9% have the least portion on open porosity. The other parameters including SiC, M.t and Cf have 2.9%, 3.6% and 3.8% on open porosity respectively.

Macor coatings on 316 alloys substrates were prepared by plasma spraying. The crystallization temperature, thermal expansion coefficient of mica glass-ceramic were at 900ºC and 40× 10−7/◦C respectively. The microhardness of obtained glass-ceramic coating was 6.8GPa and the coefficient friction was 0.98 .

In this paper TiB2-TiC/Ni cermet with various Ni (20, 40 and 60 wt %) content were synthesized by mechanically activated self-propagating synthesis (MASHS) and effect of the addition of Ni on synthesis parameters and microstructure of synthesized samples were investigated. First raw materials (B4C, Ti and Ni) milled in Ar atmosphere. Then milling powders analyzed by XRD. In next step powders synthesized in tube furnace. After synthesis process all samples analyzed by XRD and SEM. Ignition time of samples was decreased with Ni content increased. SEM images shows with increases Ni content microstructure of samples has been fin and pore size has been decreased. The crystalline size of synthesized samples calculated with Williamson-Hall equation. Average crystalline size of samples with 60 wt % Nickel content was 15 and 8 nm for TiB2 and TiC respectively.

CdTe thin films with 2.8 µm thickness were deposited by electron beam evaporation method. X-ray diffraction, scanning electron microscopy, UV-Vis-NIR spectroscopy and atomic force microscopy (AFM) were used to characterize the films. The results of AFM analysis revealed that the CdTe films have uniform surface. CdTe thin films were heat-treated by SnCl2 solution. Structural analysis using XRD showed that heat treatment by SnCl2 solution improves thin film crystallinity. Three-dimensional AFM images show that CdTe films have grown as nanocone arrays with maximum height of ~21 nm. The average roughness of the film surface on area of 2×2 µm2 is ~2.28 nm. The resultant films are closely packed and has smooth surface which is suitable for photovoltaic applications. A solar cell device was fabricated based on electron beam deposited poly-crystalline CdTe and CdS thin film as absorber and window layer on ITO coated soda lime glass as substrate. The electrical characteristics of CdS/CdTe thin film solar cells were investigated under illumination. From the current-voltage characteristics of fabricated device a typical rectifying photovoltaic behavior was obtained.

In this investigation, Eu3 doped YVO4 /YBO3 phosphors were synthesized individually by conventional solid state method at 1100 °C under atmosphere condition. Meanwhile, different amounts of LiClwere used as the flux compound to modify the morphology of the phosphor particles and also final luminescence properties. It was concluded that even small amounts of fluxes play a vital role in the growth of particles. The photoluminescence emission spectra of the phosphors were measured at λexc= 240 and 310 nm, respectively. It was found that using 2 wt% of flux compounds has a significant influence on the emission enhancement of YVO4:Eu3 and YBO3:Eu3 phosphors.

The current research was focused on synthesizing potassium sodium niobate (KNN) piezoelectric ceramics for the system (K0.48Na0.52) NbO3 by high energy ball milling process for 15h at the speed of 300 rpm. The blended nano-crystalline powder was calcined in conventional box furnace at 700oC, 800oC and 900oC for duration of 5h, 7h and 10h. Diffraction result of calcine powder confirmed the formation of pure perovskite structure at 900°C, 7h along with the phase transformation from orthorhombic to tetragonal crystal structure but resulted in the formation of secondary phases at 900°C, 10h. Fourier Transmittance analysis was carried out for 700°C, 800°C and 900°C to obtain the adsorption or emission of KNN nano powders and identified the stable crystal structure at 900°C, 7h. Hence optimized calcination parameters were 900°C, 7h. The study of mass loss before and after calcination identified the decomposition of the carbon atoms into bicarbonates and completion of the chemical reaction. The study confirmed that calcination kinetics were time and temperature dependent. Morphology of the calcined powders revealed cubical structure with good compactness for 900oC of 7h calcination with the grain size in the range of 65nm-120nm.