Effect of Micro Scale Textures on Drilling Performance of Carbide Tools in Dry and Wet Machining of Ti-6Al-4V

2016 ◽  
Author(s):  
Niketh Saseendran ◽  
Samuel Gonumakulapalle Lodi
Keyword(s):  
Laser Scanning ◽  
Thrust Force ◽  
Average Diameter ◽  
Mechanical And Thermal Properties ◽  
Drill Bit ◽  
Drilling Performance ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Dry And Wet Conditions ◽  
Micro Dimples

Surface textures helps in controlling the tribological, optical, mechanical, and thermal properties on the surfaces. The recent advancements in precision machining, makes it possible to generate micro/nano patterns on the surfaces with high dimensional control. In the present work an attempt has been made to reduce the thrust force and torque developed during drilling super alloy, Ti-6Al-4V by creating micro dimples on the tool surfaces. Circular dimples having an average diameter of 35 micrometer were created on the flute and margin side of the drill bit using Nd:YAG laser. Scanning electron microscopy analysis has been done to evaluate the quality of generated micro dimples. Drilling experiments were carried out on the titanium alloy in both dry and wet conditions using flute textured, margin textured and non textured tool for understanding the effect of micro textures on the tool. From the force analysis it was observed that in both dry and wet conditions there was a considerable reduction in thrust force and torque. Surface inspections of the drill bit were performed using Stereomicroscope for investigating the titanium buildup on the cutting tool surfaces. Results showed that the margin textured tool performed better than the flute textured and untextured tool in both dry and wet conditions.

scholarly journals Three-Dimensional Nano-Morphology of Carbon Nanotube/Epoxy Filled Poly(methyl methacrylate) Microcapsules

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1387 ◽  
Author(s):  
M. Galip Icduygu ◽  
Meltem Asilturk ◽  
M. Akif Yalcinkaya ◽  
Youssef K. Hamidi ◽  
M. Cengiz Altan
Keyword(s):  
Confocal Microscopy ◽  
Methyl Methacrylate ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Laser Scanning Confocal Microscopy ◽  
Poly Methyl Methacrylate ◽  
Scanning Confocal Microscopy ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Average Size

The three-dimensional nano-morphology of poly(methyl methacrylate; PMMA) microcapsules filled with carbon nanotubes (CNTs) and epoxy resin were investigated by various microscopy methods, including a novel, laser scanning confocal microscopy (LSCM) method. Initially, PMMA microcapsules containing various amounts of CNTs were synthesized by a solvent evaporation method. Scanning electron microscopy analysis showed that pore-free, smooth-surface microcapsules formed with various types of core-shell morphologies. The average size of CNT/epoxy/PMMA microcapsules was shown to decrease from ~52 μm to ~15 μm when mixing speed during synthesis increased from 300 rpm to 1000 rpm. In general, the presence of CNTs resulted in slightly larger microcapsules and higher variations in size. Moreover, three-dimensional scans obtained from confocal microscopy revealed that higher CNT content increased the occurrence and size of CNT aggregates inside the microcapsules. Entrapped submicron air bubbles were also observed inside most microcapsules, particularly within those with higher CNT content.

scholarly journals Synthesis and mechanical characterization of a non-woven nanofiber by the electrospinning technique

DYNA ◽  
2019 ◽  
Vol 86 (209) ◽  
pp. 64-72
Author(s):  
Edwin Edgardo Espinel Blanco ◽  
Nelson Escobar-Mora ◽  
Lina Marcela Hoyos-Palacio ◽  
Martin Fabián Sarmiento-Gaviria
Keyword(s):  
Electron Microscopy ◽  
Mechanical Characterization ◽  
Average Diameter ◽  
Electrospinning Technique ◽  
Acid Ratio ◽  
Nanostructured Polymer ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Scanning Electron

A non-woven nanofiber or polymeric cover is synthesized with nylon-6 as the base polymeric material. Different acid relationships (formic/acetic) were tested in the electrospinning equipment, until defining by macroscopic observations and SEM Scanning Electron Microscopy analysis the adequate acid ratio 3:2 and the average diameter of the nanofibers in 350nm, defining the parameters to operate the electrospinning. According to ASTM D 882 standard, the Tensile Strength was calculated for stresses applied horizontally and vertically to the direction of the nanofibers. With the standards ASTM D 7490 and ASTM G-15 the wettability was determined by measuring the contact angle, finding that it has hydrophilic properties with high wettability, adhesiveness and surface energy. Nanostructured polymer covers can be used for biological isolation in health care areas, as a protective barrier to control the spread of infections. 

scholarly journals Comparative Analysis in Drilling Performance of AA7075 in Different Temper Conditions

2021 ◽  
Author(s):  
ESER YARAR ◽  
Alpay Tamer ERTURK ◽  
Funda Gül KOÇ ◽  
Fahri VATANSEVER
Keyword(s):  
Tool Wear ◽  
Surface Quality ◽  
Heat Generation ◽  
Chip Formation ◽  
Feed Rate ◽  
Thrust Force ◽  
Spindle Speed ◽  
Drill Bit ◽  
Microstructural Properties ◽  
Drilling Performance

Abstract AA7075 is one of the most suitable materials for aerospace, aircraft, and defense applications with its high yield strength and low-density. In many other modern machining methods, conventional drilling remains the most extensive material removal process in industrial components. The main objective of this study is examining the machinability and surface quality conditions of the AA7075 material with different temper conditions. For this purpose, various temper treatments are implemented to evaluate the impact of microstructural properties on tool wear and surface quality of the drilled holes. The drilling operations have been done on O, F, T4, T6, and T7 temper conditions. Process parameters were three different spindle speeds (715, 1520, and 3030 rev/min) and three feed rates (0.1, 0.2, and 0.3 mm/rev) with HSS-G high-performance ground standard twist drill bit. The present work deals with the effects of temper conditions on thrust force, drilling temperature, tool wear, surface integrity, and chip morphology. Drilling performance is related to the intrinsic microstructural properties of temper conditions. Response surface methodology was used in the evaluation of experiment results. The optimization results showed that while thrust force and torque are not significantly affected by change in spindle speed, they are sensitive to increase in feed rate. Heat-generation on the drill bit is the lowest at low levels of both the feed rate and spindle speed parameters. Among different temper conditions, the AA7075-T6 condition sample is processed with continuous chip formation and resulted in the best hole surface quality. The 3D finite element modelling of the drilling process was carried out, and the drilling performance of AA7075-T6 was evaluated in terms of thrust force, heat generation, and chip formation.

Low concentration of guanidine hydrochloride induces the formation of an aggregation-prone state in α-urease

2004 ◽  
Vol 82 (2) ◽  
pp. 305-313 ◽  
Author(s):  
F -O McDuff ◽  
A Doucet ◽  
M Beauregard
Keyword(s):  
Tertiary Structure ◽  
Molten Globule ◽  
Guanidine Hydrochloride ◽  
Average Diameter ◽  
Secondary Structures ◽  
Fluorescence Measurements ◽  
Protein Fibrils ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
The Impact

Canavalia ensiformis (jack bean) α-urease is a hexameric protein characterized by a complex denaturation mechanism. In previous papers, we have shown that a hydrophobic 8-anilino-1-naphthalenesulfonic acid (ANSA) binding conformer could be populated in a moderate concentration of denaturant. This state was obtained under conditions that had no detectable impact on its tertiary structure, as indicated by fluorescence measurements. In the present study, we further characterized this ANSA-binding state in an attempt to understand urease behavior. Evidence presented here shows that the presence of ANSA was not required for the generation of the conformer and that its affinity for ANSA came from an increase in hydrophobicity leading to aggregation. Circular dichroism investigation of urease revealed that it had periodical secondary structure content similar to Klebsiella aerogenes urease (secondary structures calculated on the basis of crystallographic data). The impact of 0.9 M guanidine hydrochloride (GuHCl) on soluble urease secondary structures was minimal but is compatible with a slight increase in beta-sheet structures. Such modification may indicates that aggregation involves amyloid-like fibril formation. Electron microscopy analysis of urease in the absence of GuHCl revealed the presence of urease hexamers (round shape 13 nm in diameter). These particles disappeared in the presence of moderate denaturant concentration owing to the formation of aggregates and fibril-like structures. The fibrils obtained in 1.5 M GuHCl had an average diameter of 6.5 nm, suggesting that urease hexamers dissociated into smaller oligomeric forms when forming such fibrils.Key words: protein structure, protein folding, denaturation, aggregation, multimeric proteins, protein fibrils, hydrophobicity, molten globule state.

SYNTHESIS OF MONODISPERSE Mn3O4 NANOCRYSTALS

2009 ◽  
Vol 08 (03) ◽  
pp. 281-283 ◽  
Author(s):  
MASOUD SALAVATI-NIASARI ◽  
FATEMEH DAVAR
Keyword(s):  
Photoelectron Spectroscopy ◽  
Average Diameter ◽  
Binding Energies ◽  
X Ray Diffraction ◽  
Transmission Electron Microscopy Analysis ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
20 Nm

Mn3O4 nanocrystals have been prepared using [bis(2-hydroxyacetophenato)manganese(II)] as precursor. Transmission electron microscopy analysis demonstrated nanocrystals Mn3O4 with an average diameter of about 20 nm. The structural study by X-ray diffraction indicates that these nanocrystals have pure tetragonal phase. The phase pure samples were characterized using X-ray Photoelectron Spectroscopy for Mn 2p level. The values of binding energies are consistent with the relative values reported in the literature.

Material analysis techniques using the ion mill

1996 ◽  
Vol 54 ◽  
pp. 1034-1035
Author(s):  
J. P. Benedict ◽  
R. M. Anderson ◽  
S. J. Klepeis
Keyword(s):  
Polished Surface ◽  
Surface Material ◽  
Analysis Techniques ◽  
Material Analysis ◽  
Optical Inspection ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Argon Ions ◽  
The Impact ◽  
Scanning Electron

Ion mills equipped with flood guns can perform two important functions in material analysis; they can either remove material or deposit material. The ion mill holder shown in Fig. 1 is used to remove material from the polished surface of a sample for further optical inspection or SEM ( Scanning Electron Microscopy ) analysis. The sample is attached to a pohshing stud type SEM mount and placed in the ion mill holder with the polished surface of the sample pointing straight up, as shown in Fig 2. As the holder is rotating in the ion mill, Argon ions from the flood gun are directed down at the top of the sample. The impact of Argon ions against the surface of the sample causes some of the surface material to leave the sample at a material dependent, nonuniform rate. As a result, the polished surface will begin to develop topography during milling as fast sputtering materials leave behind depressions in the polished surface.

Effects of Various Antioxidant Pretreatment Modalities on Adhesion to Sound and Caries-Affected Dentin: An In Vitro Study

2021 ◽  
pp. 232020682199798
Author(s):  
Beyza Unalan Degirmenci ◽  
Alperen Degirmenci ◽  
Emine Kara
Keyword(s):  
Bond Strength ◽  
In Vitro Study ◽  
Natural Antioxidants ◽  
Microtensile Bond Strength ◽  
Mandibular Molar ◽  
Electron Microscopy Analysis ◽  
Molar Teeth ◽  
Microscopy Analysis ◽  
Two Parameters

Aim: Natural antioxidants were offered as the answer of dentin adhesion issue. The aim of this study is to investigate the effects of proanthocyanidin and lycopene as pretreatment agents on the sound and caries-affected dentin surface on microtensile bond strength and microleakage. Materials and Methods: This study was designed as in vitro because of that 84 mandibular molar teeth were collected. Forty-two of the included teeth were carious teeth, while the other 42 were without caries. Sixty of them were used for microleakage and 24 for microtensile bond strength testing and scanning electron microscopy analysis. The samples were divided into six subgroups randomly according to dentin pretreatments: 5% proanthocyanidin, 5% lycopene, and no antioxidant application. After the restorative procedures, samples were attached to the microtensile tester. Samples were subjected to tensile stress in the load cell until they broke at a speed of 0.5 mm per min. Microtensile bond strength (µTBS) and microleakage test data were analyzed with two-way analysis of variance, Bonferroni correction, and Tamhane’s T2 tests. Results: Two-way variance analysis showed that dentin pretreatment applications, dentin substrate, and the interaction between these two parameters had statistically significant effects on µTBS values ( P < .001). There was no difference between dentin pretreatment applications in terms of microleakage scores ( P > .05). Conclusion: The application of dentin pretreatment with proanthocyanidin is a successful procedure that increases the bond strength in both dentin substrate, while pretreatment with lycopene in caries-affected dentin reduces it.

scholarly journals Antiparasitic Properties of Cardiovascular Agents against Human Intravascular Parasite Schistosoma mansoni

2021 ◽  
Vol 14 (7) ◽  
pp. 686
Author(s):  
Raquel Porto ◽  
Ana C. Mengarda ◽  
Rayssa A. Cajas ◽  
Maria C. Salvadori ◽  
Fernanda S. Teixeira ◽  
...  
Keyword(s):  
Schistosoma Mansoni ◽  
Screening Strategy ◽  
Early Infection ◽  
Global Public Health ◽  
Parasitic Worm ◽  
Electron Microscopy Analysis ◽  
Health Significance ◽  
Microscopy Analysis

The intravascular parasitic worm Schistosoma mansoni is a causative agent of schistosomiasis, a disease of great global public health significance. Praziquantel is the only drug available to treat schistosomiasis and there is an urgent demand for new anthelmintic agents. Adopting a phenotypic drug screening strategy, here, we evaluated the antiparasitic properties of 46 commercially available cardiovascular drugs against S. mansoni. From these screenings, we found that amiodarone, telmisartan, propafenone, methyldopa, and doxazosin affected the viability of schistosomes in vitro, with effective concentrations of 50% (EC50) and 90% (EC90) values ranging from 8 to 50 µM. These results were further supported by scanning electron microscopy analysis. Subsequently, the most effective drug (amiodarone) was further tested in a murine model of schistosomiasis for both early and chronic S. mansoni infections using a single oral dose of 400 mg/kg or 100 mg/kg daily for five consecutive days. Amiodarone had a low efficacy in chronic infection, with the worm and egg burden reduction ranging from 10 to 30%. In contrast, amiodarone caused a significant reduction in worm and egg burden in early infection (>50%). Comparatively, treatment with amiodarone is more effective in early infection than praziquantel, demonstrating the potential role of this cardiovascular drug as an antischistosomal agent.

scholarly journals Impact Resistance of Epoxy Composites Reinforced with Amazon Guaruman Fiber: A Brief Report

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2264
Author(s):  
Raphael H. M. Reis ◽  
Fabio C. Garcia Filho ◽  
Larissa F. Nunes ◽  
Veronica S. Candido ◽  
Alisson C. R. Silva ◽  
...  
Keyword(s):  
Fiber Composite ◽  
Impact Resistance ◽  
Fiber Composites ◽  
Epoxy Composites ◽  
Impact Performance ◽  
Electron Microscopy Analysis ◽  
Ballistic Properties ◽  
Microscopy Analysis ◽  
Izod Impact ◽  
The Impact

Fibers extracted from Amazonian plants that have traditionally been used by local communities to produce simple items such as ropes, nets, and rugs, are now recognized as promising composite reinforcements. This is the case for guaruman (Ischinosiphon körn) fiber, which was recently found to present potential mechanical and ballistic properties as 30 vol% reinforcement of epoxy composites. To complement these properties, Izod impact tests are now communicated in this brief report for similar composites with up to 30 vol% of guaruman fibers. A substantial increase in impact resistance, with over than 20 times the absorbed energy for the 30 vol% guaruman fiber composite, was obtained in comparison to neat epoxy. These results were statistically validated by Weibull analysis, ANOVA, and Tukey’s test. Scanning electron microscopy analysis disclosed the mechanisms responsible for the impact performance of the guaruman fiber composites.

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