Sharif Digital Repository

Zirconia/Hydroxyapatite composites containing 20-50 wt.% 8YSZ were prepared on Ti/TiO2 substrates by electrophoretic deposition (EPD)/micro-arc oxidation (MAO) process. Titania, as an inner layer, was grown on the Ti plates using MAO treatment in order to form a strong join between substrate and HAp. These composites were produced by EPD in ethanol containing ZrO2/HAp particles at 50, 100 and 150 V in 1 min. Asprepared samples were sintered at 900, 1100 and 1300 °C. HAp, β-TCP, CaZrO3 phases were identified using X-ray diffractometry analysis (XRD). Scanning electron microscopy (SEM) utilized to study the surface morphology indicated a crack free microstructure at 1300 °C  

In this report, crack-free nanostructured barium titanate thin films are prepared by a sol-gel processing method. Glacial acetic acid, barium acetate, titanium tetraisopropyl alkoxide, 2-propanol and deionized water are used as precursors for preparing stable precursor solution. Then very thin films (thickness=26 nm) are deposited on fused silica substrates. In order to prepare crack-free thin films of BaTiO3, much attention is given to solvent evaporation process and a controlled pre-drying process is developed. It is found that the control of the process, especially in the initial stage of drying process is crucial and important for preparation of the crack-free ultrathin nanostructured... 

HVOF-sprayed coatings (WC-17%Co) and hard chromium coatings corrosion resistances have been compared through electrochemical polarization test in 3.5% NaCl solution. WC-17%Co alloy coatings were deposited on mild steel substrates by High Velocity Oxy-Fuel (HVOF) spray process. The layers of standard and crack free hard chromium coatings were prepared by using Direct Current (DC) and Pulse Current (PC) electroplating process on the mild steel substrates. Hard chromium coatings was characterized as a reference material, to verify whether HVOF-sprayed coatings are suitable as a hard chromium coatings replacement. The microstructure of the coatings was examined by OM, SEM and XRD. Standard hard... 

To perform a long lasting, crack-free repair welding on ultrahigh strength steels, the filler metal must be chosen and applied properly. Avoiding several short-term repairs or replacements, the repaired weldment should reveal comparative characteristics such as wear resistance, toughness and hardness to base metal. In the present study, a novel functionally graded material have been introduced to obtain enhanced wear resistance and hardness at surface as well as improved fracture toughness at fusion line of repaired weldments. A comparative study of wear resistance of repaired weld metals has been carried out by pin-on-disk apparatus at 5N normal load and 0.14ms-1 sliding speed. Fracture... 

A series of samples with different compositions and parameters were welded together. The alloys were based on Ni-8Al-8Cr-l.5Mo-0.01B %wt composition with Zr additions of 1 and 3 %wt. Crack-free full-penetration welds of castable nickel aluminide alloy were performed using autogenous GTAW technique. It was found that Ni-Ni5Zr eutectic was associated with solidification cracks. Alloys were fully dendritic and also, weld metal consisted of columnar and axial dendrites beside the fusion line and in the middle, respectively. Optical and scanning electron microscopy (SEM) techniques were employed to characterize the composition as well as the weld structure. X-Ray diffraction was utilized to... 

Electrophoretic technique was used to deposit micro- and nano-sized aluminum nitride coatings on stainless steel surfaces by using a well-dispersed stable suspension produced by addition of AlN powder plus a small amount of iodine to ethanol. Parabolic regime governed the deposition. Electrophoretic deposition for 240 s at 100 V resulted in formation of a uniformly dense film on the top, but a porous inhomogeneous layer at the bottom. This was attributed to fast deposition of coarse particles and/or agglomerates at large electric fields. After drying, micro-sized particles led to a uniform crack-free interface while nano-particles resulted in fragmented non-cohesive layers. Weight loss... 

In this paper fabrication of a 0-3 ceramic/ceramic composite lead zirconate titanate, Pb(Zr0.52Ti0.48)O3 thin film has been presented and then a pressure sensor based on multilayer thin-film PZT diaphragm contain of Lead Zirconate Titanate nanocrystalline powders was designed, modeled and optimized. This multilayer diaphragm in general acts as sensor or actuator. ANSYS was used for simulation of diaphragm. Dynamics characteristics of this multilayer diaphragm have been investigated. By this simulation the effective parameters of the multilayer PZT diaphragm for improving the performance of a pressure sensor in different ranges of pressure are optimized. The optimized thickness ratio of PZT...