scholarly journals Fracture Surface Analysis in Thixojoined Tool Steels

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
A. Kalaki ◽  
M. Ketabchi ◽  
Sh. Zangeneh
Keyword(s):  
Fracture Surface ◽  
Shear Test ◽  
Smooth Transition ◽  
Tool Steels ◽  
High Quality ◽  
Bonding Quality ◽  
Globular Microstructure ◽  
Fracture Surface Analysis ◽  
Diffusion Interface ◽  
Scanning Electron

Thixojoining has been developed for D2 and M2 tool steels. The suitable globular microstructure and excellent bonding quality are obtained through this work. Scanning electron microscopy (SEM) observation along the joint interfaces showed a smooth transition zone with no cracks. In addition, fracture surface of the shear test samples showed that the fracture mode was transgranular. Finally, based on obtained results, this method presented high quality joint with nonequilibrium diffusion interface.

The effect of nitrile-functionalized nano-aluminum oxide on the thermomechanical properties and toughness of phthalonitrile resin

2016 ◽  
Vol 29 (1) ◽  
pp. 113-123 ◽  
Author(s):  
Shuyan Shan ◽  
Xinggang Chen ◽  
Zhenjie Xi ◽  
Xiaoyan Yu ◽  
Xiongwei Qu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fracture Surface ◽  
Aluminum Oxide ◽  
Flexural Modulus ◽  
Thermomechanical Properties ◽  
Flexural Properties ◽  
Enhancement Effect ◽  
Fracture Surface Analysis ◽  
Scanning Electron

Resorcinol-based phthalonitrile (R-CN)/nano-aluminum oxide (Al2O3) nanocomposites were prepared via a two-step approach. Firstly, Al2O3 was functionalized with nitrile groups on the surface of Al2O3 nanoparticles, which was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy (SEM). The effect of nano-Al2O3 particles on thermomechanical and flexural properties has been evaluated for different weight ratios ranging between 0% and 5%. Compared with pure nano-Al2O3, nitrile-functionalized Al2O3 (CN-Al2O3) particles showed a more significant enhancement effect on the properties of R-CN resin. The storage modulus of nanocomposite with 5 wt% CN-Al2O3 reaches 2679 MPa at 25°C, which is much higher than that of the pure R-CN resin. For 3 wt% CN-Al2O3-reinforced R-CN composites, it showed an increase of 54.84% in flexural strength and 21.48% in flexural modulus. SEM was employed to explore the fracture surface of composites. Micrographs of fracture surface analysis confirmed that the toughness of R-CN resin can be improved significantly by incorporating CN-Al2O3 nanoparticles.

Fracture toughness of macro-defect-free cement using small crack techniques

1990 ◽  
Vol 5 (8) ◽  
pp. 1774-1780 ◽  
Author(s):  
Y-S. Chou ◽  
J. J. Mecholsky ◽  
M. Silsbee
Keyword(s):  
Fracture Toughness ◽  
Fracture Surface ◽  
Crack Growth ◽  
Measurement Techniques ◽  
Crack Growth Resistance ◽  
Scanning Electron Micrographs ◽  
Microstructural Effects ◽  
Fracture Surface Analysis ◽  
Scanning Electron ◽  
Good Agreement

The fracture toughness of a macro-defect-free (MDF) cement was calculated from two measurement techniques: (1) indentation-strength method and (2) fracture surface analysis (FSA). It was found that the indentation-strength method, which showed good agreement with FSA, was applicable for estimating the fracture toughness of MDF cement. The ultimate toughness was found to be 1.25 MPa m1/2 for this MDF cement, which contained 3 wt. % polymer. An R-curve (crack-growth-resistance) bchavior was also observed. Scanning electron micrographs showed extensive microcracking on the fracture surface. Microstructural effects are discussed.

scholarly journals Fatigue Crack Initiation and Propagation at High Temperature of New-Generation Bearing Steel

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 25
Author(s):  
Zhiwei Wu ◽  
Maosheng Yang ◽  
Kunyu Zhao
Keyword(s):  
Fracture Surface ◽  
Failure Mode ◽  
Electron Backscatter Diffraction ◽  
Fatigue Cracks ◽  
Fatigue Crack Initiation ◽  
Optical Microscope ◽  
Bearing Steel ◽  
Fatigue Properties ◽  
New Generation ◽  
Scanning Electron

The new generation of bearing steel has good comprehensive properties, which can satisfy most of the requirements of bearing steel in a complex environment. In the presented work, fatigue properties of 15Cr14Co12Mo5Ni2 bearing steel have been investigated by means of rotating bending fatigue tests on smooth bar specimens after carburization and heat treatment. Optical microscope, scanning electron microscopy, electron backscatter diffraction, and Image-Pro Plus software were used to analyze the fracture, microstructure, and carbides. The results suggest that the fatigue strength at room temperature and 500 °C is 1027 MPa and 585 MPa, respectively. Scanning electron micrographic observations on the fracture surface of the fatigue specimens at 500 °C show that fatigue cracks usually initiate from voids in the carburized case and oxide layer on the surface of steel. The failure mode in the carburized case is a quasi-cleavage fracture, and with the increase of crack propagation depth, the failure mode gradually changes to fatigue and creep-fatigue interaction. With the increase of the distance from the surface, the size of the martensite block decreases and the fracture surface shows great fluctuation.

scholarly journals Development and Comparative Analysis of Electrochemically Etched Tungsten Tips for Quartz Tuning Fork Sensor

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 286
Author(s):  
Ashfaq Ali ◽  
Naveed Ullah ◽  
Asim Ahmad Riaz ◽  
Muhammad Zeeshan Zahir ◽  
Zuhaib Ali Khan ◽  
...  
Keyword(s):  
Tuning Fork ◽  
Mechanical Stability ◽  
Electrochemical Etching ◽  
Research Work ◽  
Cone Angle ◽  
Quartz Tuning Fork ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
High Quality ◽  
Scanning Electron

Quartz Tuning Fork (QTF) based sensors are used for Scanning Probe Microscopes (SPM), in particular for near-field scanning optical microscopy. Highly sharp Tungsten (W) tips with larger cone angles and less tip diameter are critical for SPM instead of platinum and iridium (Pt/Ir) tips due to their high-quality factor, conductivity, mechanical stability, durability and production at low cost. Tungsten is chosen for its ease of electrochemical etching, yielding high-aspect ratio, sharp tips with tens of nanometer end diameters, while using simple etching circuits and basic electrolyte chemistry. Moreover, the resolution of the SPM images is observed to be associated with the cone angle of the SPM tip, therefore Atomic-Resolution Imaging is obtained with greater cone angles. Here, the goal is to chemically etch W to the smallest possible tip apex diameters. Tips with greater cone angles are produced by the custom etching procedures, which have proved superior in producing high quality tips. Though various methods are developed for the electrochemical etching of W wire, with a range of applications from scanning tunneling microscopy (SPM) to electron sources of scanning electron microscopes, but the basic chemical etching methods need to be optimized for reproducibility, controlling cone angle and tip sharpness that causes problems for the end users. In this research work, comprehensive experiments are carried out for the production of tips from 0.4 mm tungsten wire by three different electrochemical etching techniques, that is, Alternating Current (AC) etching, Meniscus etching and Direct Current (DC) etching. Consequently, sharp and high cone angle tips are obtained with required properties where the results of the W etching are analyzed, with optical microscope, and then with field emission scanning electron microscopy (FE-SEM). Similarly, effects of varying applied voltages and concentration of NaOH solution with comparison among the produced tips are investigated by measuring their cone angle and tip diameter. Moreover, oxidation and impurities, that is, removal of contamination and etching parameters are also studied in this research work. A method has been tested to minimize the oxidation on the surface and the tips were characterized with scanning electron microscope (SEM).

scholarly journals Characterization by Scanning Electron Microscopy on Drill Boride and Drilling Performance of Tool Steels

2020 ◽  
Vol 26 (S2) ◽  
pp. 388-390
Author(s):  
Victor Olmos Domínguez ◽  
Marco Doñu Ruiz ◽  
Noe Lopez Perrusquia ◽  
Leopoldo Garcia Vanegas
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Tool Steels ◽  
Drilling Performance ◽  
Scanning Electron
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