scholarly journals Mechanical Properties of Tonalite Subjected to Combined Effects of Chemical Corrosion and Freeze-Thaw Cycles

2019 ◽  
Vol 9 (18) ◽  
pp. 3890 ◽  
Author(s):  
Chao Xu ◽  
Youliang Chen ◽  
Suran Wang ◽  
Akbar Javadi ◽  
Xi Du ◽  
...  

This paper presents an investigation into the coupled effects of chemical corrosion (by Nitric acid solution) and freeze-thaw cycles on the physical and mechanical properties and damage deterioration of tonalite specimens. The experiments included the uniaxial compression test, three-point bending test, the Young’s modulus test, the X-ray diffraction test and the scanning electron microscope test. The damage condition of tonalite specimens was analyzed using scanning electron microscope (SEM). The experimental results reveal that chemical erosion has a significant influence on the propagation of micro cracks and accelerates the development of damage in the tonalite samples under monotonic loading. Due to cementation, no noticeable difference in uniaxial compressive strength was observed between the specimens subjected to combined effects of chemical corrosion and freeze-thaw cycles and those subjected to freeze-thaw cycles only. The amount of cementing materials in the chemically treated samples was found using SEM, which shows that chemical reactions promoted mechanical properties to some extent.

2018 ◽  
Vol 19 (3) ◽  
pp. 283-286
Author(s):  
Deepika Gupta ◽  
Amit K Gupta ◽  
Ajay K Gupta ◽  
Gita Shukla

ABSTRACT Introduction Orthodontic treatment these days is increasing in demand, and therefore, it is relatively imperative for the orthodontist to prescribe the use of fluoride-containing products, such as mouthwashes and gels, to help prevent dental caries and maintain healthy oral health. The aim of the study was to assess and evaluate the effects of fluoride prophylactic agents on mechanical properties of nickel titanium (NiTi) wires during orthodontic treatment using scanning electron microscope (SEM). Materials and methods We used the commercially available round preformed NiTi orthodontic archwire (3M company) and three different mouthwash solutions, i.e., Phos-Flur gel (1.1% sodium acidulated phosphate fluoride, APF, 0.5% w/v fluoride, pH = 5.1; Colgate Oral Pharmaceuticals) and Prevident 5000 (1.1% sodium fluoride neutral agent, 0.5% w/v fluoride, pH = 7; Colgate Oral Pharmaceuticals). All the specimens were subjected to a three-point bending test on a universal testing machine. To observe the surface morphological changes, one wire from each group was randomly selected and observed under a SEM. Results It was observed that there was not much difference in the values of both modulus of elasticity and yield strength obtained after loading of stress on the wires in all the three experimental conditions. A significant difference in both modulus of elasticity and yield strength was observed during unloading of stress. Further, when the surface characteristics were observed for all the specimens using SEM images, it was observed that NiTi wires treated with Phos-Flur showed large surface defects which appeared as round, pitted areas depicting corrosion, numerous white inclusions, and overall damaged surface structure of the wire as compared with the control. Conclusion Thus, fluoridated mouthwashes are essential to maintain good oral hygiene and decrease instance of caries in patients undergoing orthodontic treatment. The prophylactic usage of topical fluoride agents on NiTi wire seems to diminish the mechanical properties of the orthodontic wire that could significantly affect future treatment outcomes. Clinical significance It has been proved that fluoride mouthwashes/gels do affect the structural surface qualities and strength of wires used during the orthodontic treatment irrespective of the composition of the wires. Therefore, it is the responsibility of the clinician to prescribe these prophylactic agents carefully while keeping in mind their pH so that the overall result of the treatment may not be hampered and delayed due to change in properties of the wires used. How to cite this article Gupta AK, Shukla G, Sharma P, Gupta AK, Kumar A, Gupta D. Evaluation of the Effects of Fluoride Prophylactic Agents on Mechanical Properties of Nickel Titanium Wires using Scanning Electron Microscope. J Contemp Dent Pract 2018;19(3):283-286.


2012 ◽  
Vol 525-526 ◽  
pp. 277-280
Author(s):  
Guo Jin ◽  
Xiu Fang Cui ◽  
Er Bao Liu ◽  
Qing Fen Li

The effect of the neodymium content on mechanical properties of the electro-brush plated nanoAl2O3/Ni composite coating was investigated in this paper. The microstructure and phase structure were studied with scanning electron microscope (SEM) and X-ray diffraction (XRD). The hardness and abrasion properties of several coatings with different neodymium content were studied by nanoindentation test and friction / wear experiment. Results show that the coatings are much finer and more compact when the neodymium was added, and the hardness and abrasion property of the coatings with neodymium were improved obviously. Besides, the small cracks conduced by the upgrowth stress in the coatings were ameliorated when the rare earth neodymium was added. The improvement mechanism was further discussed.


2020 ◽  
Vol 841 ◽  
pp. 114-118
Author(s):  
Marco Antonio Navarrete Seras ◽  
Francisco Javier Domínguez Mota ◽  
Elia Mercedes Alonso Guzmán ◽  
Wilfrido Martínez Molina ◽  
Hugo Luis Chávez García ◽  
...  

. Banks of stone materials from Michoacán, Mexico were characterized, since they are used in the construction of infrastructure in the area. With these materials are made hydraulic concrete mixtures or asphalt mixtures, foundations, paving stones and in restoration of historical monuments. The rocks analyzed and characterized, come from banks of volcanic stone materials and banks of crushed stone materials, which were subjected to mechanical tests such as uniaxial compression resistance (UCR), in addition was used scanning electron microscope (SEM), by means of which the characterization was carried out, obtaining morphological information of the material. The comparison of physical-mechanical properties with the elements they possess is important to estimate their behavior within ceramic matrices or as a structural element.


2011 ◽  
Vol 306-307 ◽  
pp. 754-757 ◽  
Author(s):  
Xian Qin Hou ◽  
Jian Ye Liu ◽  
He Yi Ge

The physical and mechanical properties of alumina (Al2O3) ceramics by introduction of zirconia (ZrO2) fiber were studied. ZrO2/Al2O3ceramics at different sintering temperature was investigated by porosity and water absorption measurements, flexual strength and thermal shock resistance analysis. Results showed that Al2O3 ceramics containing 15 wt% ZrO2fiber with sintering temperature of 1650°C exhibited good mechanical properties and thermal shock resistance. The porosity and water absorption were 7.4% and 0.69%, respectively. The flexual strength was 613 MPa and the thermal shock times reached 29 times. Scanning electron microscope (SEM) was used to analyze the microstructure of Al2O3 ceramics.


2007 ◽  
Vol 546-549 ◽  
pp. 241-244 ◽  
Author(s):  
Yun Qi Yan ◽  
H. Zhang ◽  
Q. Chen ◽  
H. Zhong ◽  
W.P. Weng

Rolling and punching techniques of AZ31 alloy were investigated in this paper. Various rolling experiments were carried out to make fine-grained Mg sheets. Punching tests were conducted at the temperatures range from 70 to 300 oC. The analysis revealed that there existed an excellent warm forming temperature for as-rolled AZ31 alloy. A warm deep punching tool setup using heating elements was designed and manufactured to produce the cell phone. Microstructures were observed using optical and scanning electron microscope equipped with EBSD. The textures in as-rolled and as-annealed specimens attribute to different mechanical properties along the various direction.


2015 ◽  
Vol 1113 ◽  
pp. 23-27 ◽  
Author(s):  
Alireza Fakhari ◽  
Abdul Razak Rahmat ◽  
Mat Uzir Wahit ◽  
Amirali Khalili ◽  
Zyad Salem Alsagayar

In this study a series of green thermoset resins have been produced from blending acrylated epoxidized palm oil (AEPO) and unsaturated polyester (UPE). The UPE/AEPO ratio was changed between 90/10 and 70/30 wt%. The curing behavior and morphology of hybrid systems were investigated by differential scanning calorimeter (DSC) and Scanning electron microscope (SEM). Moreover, studies on mechanical properties were performed by tensile and flexural tests. The results revealed that, these green thermoset resins exhibit thermo mechanical properties comparable to those of commercial unsaturated polyesters.


2013 ◽  
Vol 750-752 ◽  
pp. 671-674
Author(s):  
Rong Hua Zhang ◽  
Yong An Zhang ◽  
Bao Hong Zhu

In this paper, the Al-8.5Fe-1.3V-1.7Si alloys were fabricated by spray forming and extrusion process. The microstructure and mechanical properties of the alloy were investigated by means of metallographic, scanning electron microscope and tensile test. The results indicate that the tensile strength of the extrued alloys can reach 353MPa, the yield strength 300MPa, elongation 19.12%, at room temperature. At 250°C, the tensile strength of the extrued alloys can reach 221MPa, the yield strength 208MPa, elongation 13.33%.


2011 ◽  
Vol 236-238 ◽  
pp. 1949-1953 ◽  
Author(s):  
Ji Yan Liu ◽  
Xue Qing Liu

A biodegradable gradient polymeric membrane based on chitosan (CS) and polyvinyl alcohol (PVA) has been prepared by microwave technique. The composition and morphology variation along the thickness direction in membrane were measured by elemental analysis and scanning electron microscope (SEM). The tensile properties of CS/PVA gradient membrane were tested. Results showed that the content of either polymer shows a gradient variation along the thickness direction. SEM photographs exhibit that morphology also evolves gradually with the varying percentage ratio of two polymers. As a result of such variations in composition and structure, the mechanical properties on both sides exhibit a significant difference. Compared with conventional isotropic membrane, gradient membrane has improved mechanical properties.


2021 ◽  
Vol 9 ◽  
Author(s):  
Xiaojian Cao ◽  
Han Zhang ◽  
Jun Yu ◽  
Tianchong Yu ◽  
Yuxing Qing

Determination of the mechanical properties of rock containing pre-existing cracks under tension condition is of great significance to understand the failure process of rock in engineering. This paper presents the experimental results of sandstone containing pre-existing cracks under Brazilian compression. The characteristics of the microcracks were analyzed by a scanning electron microscope. The results show that the rock containing pre-existing cracks has an obvious anisotropic characteristic. When the crack inclination is 45°, the rock has the minimum tensile strength and the weakest axial deformation resistance.


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