The process of interference fit and bolt clamping force are two effective techniques for improving the fatigue life of the joints and are used in various industries, especially in aerospace and automotive. Most of the previous studies have investigated separate effects of the interference fit and bolt clamping force on the fatigue life of the specimens. In the present research fatigue behavior of interference fitted specimens combined with bolt clamping force has been investigated yet. On the other hand, the pervious researches on the interference fit and bolt clamping force have been studied at laboratory temperature and the effect of temperature changes has not been investigated. To investigate the effect of temperature on the fatigue life of specimens, two different temperatures (i. e. 60° C and 120° C), aside from room temperature, were selected and fatigue life of specimens are studid at these tempratures. The fatigue tests were performed on the specimens of Al-alloy 7075-T6 alloy to obtain S-N data.

Introduction: Metal-ceramic restorations have been commonly used in dentistry. These restorations have both the esthetics of porcelain and the strength and durability of metal. Noble alloys and base-metal alloys are usually used for metal-ceramic restorations. Applications of base-metal alloys has been developed because of economic considerations, mechanical properties and low density. Remelting of used alloys is a common way in dental labs to reduce the costs of fixed prostheses. Few studies have been performed on the effect of recasting alloys on the metal-ceramic bond strength. The purpose of this study was to evaluate the effect of commond alloy recasting on metalceramic bond strength.Materials & Methods: In this laboratory-experimental study, 23 waxed patterns in the size of 0.5´3´25 millimeter were cut with bisturi blade. Wax patterns were sprued, burned out and casted with commend alloy. The second group has the same method although they consisted of equal amount of fresh alloy and alloy remnants cast only once, the third and fourth group contained 50% fresh alloy and 50% used alloy of last group. After sandblasting, grinding and surface preparation, porcelain application was done with Noritake porcelain. samples fractured with 3-point bending test by Universal Testing machine at the speed of 0.5 mm per minute. Finally, the results were analyzed by ANOVA (p value=0.007).Results: The results indicate that the highest mean values of fracture strength of porcelain to metal was in the first group (30.9 N) and then squencely in the group 3 (28.7 N), group 2 (26.8) and group 4 (24.3 N).There is a significant difference between group 1 and 2 (p value=0.03), group 1 and 4 (p value=0.001) and group 3 and 4 (p value= 0.02). There was no significant difference between group 1, 3 (p value=0.26), group 2 and 3 (p value=0.3) and group 2 and 4 (p value=0.18).Conclusion: Recasting of base metal alloys statistically decrease the bond strength of porcelain to metal.

Background & aim: Today, the high silver amalgam has been mentioned because of its appropriate properties so purpose of this study was the evaluation of bond strength of composite to high silver amalgam by using different bonding agents.Methods and materials: In this experimental study, 52 acrylic cylinders were made and amalgam which contains of 60%Ag were condensed into this cylinders, amalgam surfaces were roughened by diamond bur and all samples were immerged in ultrasonic bath. Then specimens divided into 4 groups of 13 samples: group (1) Amalgam+Alloy primer+single bond, group (2) Amalgam+Alloy primer+G.bond, group (3) Amalgam+single bond+G.bond, group (4) Amalgam+G.bond. Resin composite was bonded to prepared amalgam specimens by using translucent polyethylene mold and cured by LED Turbo and tested by universal testing machine for shear bond strength and finally data were analyzed with one-way analysis of variance and LSD test.Results: In this study, the greatest values of bond strength were related to bonded specimens of use of Alloy primer+G.bond bonding agent and lowest values were related to bonded specimens use of single bond bonding agent and mean shear bond strength in 4 groups had statistically significant difference (P=0.002).Conclusion: Combination of alloy primer and G.bond. bonding agent increased the bond strength between composite and high silver amalgam significantly

Introduction: The objective of this study was to compare the mechanical and structural properties of the nickel-titanium (Ni-Ti) alloy already used in endodontics with titanium-molybdenum (Ti-Mo) and titanium-niobium (Ti-Nb) alloys to determine if these can be suggested in the manufacture of endodontic files. Methods and Materials: Orthodontic wires made of the different alloys were used. The previously mentioned alloys were characterized by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and torsion tests. Cyclic fatigue tests were performed on a simulated canal with a curvature of 86° to 375 rpm. The fractured surfaces of the wires were observed by means of scanning electron microscopy (SEM). A Kruskal-Wallis test and U Mann Whitney test were used to determine significant differences in cyclic fatigue between groups. Results: In the mechanical tests, similar values of torsion were found for the three alloys. In XRD, the Ti-Nb showed less structural changes. In the cyclic fatigue test, Ti-Nb was found to be significantly more resistant with respect to Ni-Ti and Ti-Mo. Conclusion: Based on our in vitro study, Ti-Nb is suggested as a possible alloy for the manufacture of rotary files due to its impressive properties.

Introduction: Nitinol (NiTi) is the most interesting smart material used in orthopedic surgery and production of artificial muscles. Considering its medical applications, Nitinol biocompatibility is, therefore, quite important. This issue is discussed in this paper.Methods: Nitinol alloy experimentally produced by melting and casting under vacuum, plus imported commercial AO samples were implanted in limb tissue of a number of male rats. Twenty one days after the implantation, fibroblast and fibrosis formation in the tissues around the alloy were studied.Results: The amount of the alloy that was corroded under the experimental invitro conditions was acceptable. The biocompatibility of the experimentally made alloy implanted in limb tissue was nearly similar to that of the imported alloy.Conclusion: According to the results obtained, utilization of Nitinol in medicine is scientifically justifiable. Possibilities of its wide industrial and medical applications favorably support the mass production of the alloy in the country, and its biocompatible parallels that of the imported material.

In this study, friction stir welding (FSW) was used for joining AL-1100 to AZ31. In the rotation speed between 400 to 800rpm and travel speed between 15 to 30mm/min, in the condition that stirring pin was inserted in Mg side of weld, friction stir welded samples without any defect were made. In high rotation speed, intermetallic compounds were seen in the XRD results of the stir zone. The best tensile strength, about 122MPa, was reached in rotation speed of 570rpm and travel speed of 20mm/min.

The effect of length variation on the magnetic properties of NiFe alloy nanowires electrodeposited into the alumina template was investigated. The diameter (45±2.5 nm) and length (~1.9, 7.12, 8.3, 9.5 and 13.3mm) of the nanowires were estimated from scanning electron microscopy images. Energy dispersive spectroscopy results showed Ni3Fe7 composition of the alloy nanowires. The magnetic properties of the samples were investigated by vibrating sample magnetometer. It showed that with increasing the length of the nanowires from 1.9±0.1mm to 13.3±0.66mm, coercivity reduced from 1050 Oe to 705 Oe and squareness reduced from 0.64 to 0.46. The results proved increasing the magnetostatic interaction between the nanowires with length. Progress toward the multi-domain behavior was predicted caused to drastically reduce in the coercivity.

The nanocrystallization of Co67Fe4Cr7Si8B14 amorphous ribbons which prepared by planar flow melt spinning process (PFMS) was investigated. Crystallization of the ribbons was studied by differential thermal analysis (DTA), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The DTA result of amorphous ribbon at heating rate of 10oC/min showed occurrence of phase transitions in two stages. The ribbons were isothermally annealed for 30 minutes in argon atmosphere at different temperatures between 300 and 650oC with 25oC steps. The magnetic properties of annealed samples were measured using a vibrating sample magnetometer (VSM). The VSM results revealed that optimum soft magnetic properties occurred at 400oC. XRD patterns showed that the samples isothermally annealed up to 450oC were amorphous, while TEM results at 400oC indicated 7-8 nm mean size nanocrytallites in amorphous matrix and size of the nanocrystallites increased by increasing temperature. Also by X-ray diffraction pattern, precipitation of different phases at higher temperatures confirmed.

n this study, the kinetics of nanocrystallization of amorphous Finemet alloys is investigated under nonisothermal condition. In order to estimate kinetic parameters, differential scanning calorimetric analyses of the amorphous samples were performed at various heating rates. These results show that the crystallization of the α Fe phase starts at around 450 ̊ C. X-ray diffraction pattern samples confirm these results. According to the XRD results, the crystallite size of the sample annealed at 450 ̊ C and 550 ̊ C were 12 nm and 19 nm, respectively. The variable activation energy of crystallization was calculated, based on differential scanning calorimetric results and according to Vyazovkin advanced isoconversional method. Results show that, the activation energy is variable as a function of transformed fraction and increases from 290 to 390 kJ mol-1. Variation of activation energy confirms the complexity of the nanocrystallization process. Numerical reconstruction of the reaction model using experimental data showed that nanocrystallization mechanism could not be described with a single theoretical model. But it is closer to three dimensional phase boundary reaction mechanism. Rrounded and isotropic crystallites observed on the TEM images confirmed these results.