Initial Hardness Response and Hardness Profiles in the Study of Woodward–Hoffmann Rules for Electrocyclizations

2008 ◽  
Vol 4 (4) ◽  
pp. 595-602 ◽  
Author(s):  
F. De Proft ◽  
P. K. Chattaraj ◽  
P. W. Ayers ◽  
M. Torrent-Sucarrat ◽  
M. Elango ◽  
...  
Keyword(s):  
Initial Hardness ◽  
Hardness Response

Woodward-Hoffmann rules in density functional theory: Initial hardness response

2006 ◽  
Vol 125 (21) ◽  
pp. 214101 ◽  
Author(s):  
Frank De Proft ◽  
Paul W. Ayers ◽  
Stijn Fias ◽  
Paul Geerlings
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Functional Theory ◽  
Initial Hardness ◽  
Hardness Response

Bulk Copper-Nanodiamond Nanocomposites; Processing and Properties

2008 ◽  
Vol 587-588 ◽  
pp. 443-447 ◽  
Author(s):  
Jose Brito Correia ◽  
Vanessa Livramento ◽  
Nobumitsu Shohoji ◽  
Elena Tresso ◽  
Kazunori Yamamoto ◽  
...  
Keyword(s):  
Significant Proportion ◽  
High Strength ◽  
Copper Matrix ◽  
Nanostructured Material ◽  
Engineering Material ◽  
Composite Powders ◽  
Major Drawback ◽  
Transmission Electron ◽  
Structural And Functional Properties ◽  
Initial Hardness

Copper has widespread use as engineering material, because of its structural and functional properties, notably high thermal and electrical conductivity. A major drawback of this base metal and its alloys is a relatively low hardness. This precludes its utilization in applications in which both high conductivity and high strength/hardness are needed, e.g. in injection moulds for plastics. Nanostructured metals and nanocomposites are ways to address the low hardness problem, provided the nanostructured material is thermally stable during processing and service. In the present research, composite powders, with 5 to 30 at % nanodiamond, were consolidated into bulk samples. The copper-nanodiamond composite powders were vacuum encapsulated and extruded at 600°C. A significant proportion of the initial hardness in the powders is retained after extrusion. Transmission electron microscopy (TEM) of the extruded material indicates good bonding between the nanodiamond particles and the copper matrix. Raman spectroscopy on the consolidated samples evidences the presence of graphite, possibly due to partial disintegration of ultradisperse nanodiamond agglomerates.

scholarly journals Hardness Response Surface for U-7.5Nb-2.5Zr Alloy: A Study of Recovery/Recrystallization and Phase Transformation Interactions

2015 ◽  
Vol 2 (3) ◽  
pp. 147-156 ◽  
Author(s):  
Denise Adorno Lopes ◽  
Angelo José de Oliveira Zimmermann ◽  
Thomaz Augusto Guisard Restivo ◽  
Angelo Fernando Padilha
Keyword(s):  
Phase Transformation ◽  
Response Surface ◽  
Hardness Response

Effect of Initial Hardness on Interfacial Features in Underwater Explosive Welding of Tool Steel SKS3

2013 ◽  
Vol 23 (2) ◽  
pp. 421-428 ◽  
Author(s):  
Wei Sun ◽  
Xiaojie Li ◽  
Honghao Yan ◽  
Kazuyuki Hokamoto
Keyword(s):  
Tool Steel ◽  
Explosive Welding ◽  
Initial Hardness

Enhanced Formability of Age-Hardenable Aluminium Alloys by Incremental Forming of Solution-Treated Blanks

2013 ◽  
Vol 549 ◽  
pp. 164-171 ◽  
Author(s):  
Amirahmad Mohammadi ◽  
Hans Vanhove ◽  
Albert van Bael ◽  
Joost R. Duflou
Keyword(s):  
Precipitation Hardening ◽  
Incremental Forming ◽  
Natural Aging ◽  
Solution Treated ◽  
Treatment Conditions ◽  
Heat Treated ◽  
Initial Hardness ◽  
Aa 2024 ◽  
Cold Worked ◽  
Pre Treatment

The influence of thermal pre-treatment on the formability of a precipitation-hardening aluminium alloy AA-2024 has been studied for three different heat treatment conditions: annealed (O-temper), solution treated and quenched (W-temper) and solution heat treated, quenched and then cold worked (T-temper).The maximum draw angle has been determined and the geometrical accuracy of specific SPIF formed parts has been compared. It is found that the maximum forming angles of the blank formed in O-temper and W-temper conditions show a respective 41% and 32% increase to those of the T-temper condition (initial blank).The hardness of the material reduces significantly after annealing, while SPIF parts formed from W-temper blanks regain their initial hardness after natural aging.

Regaining the Woodward–Hoffmann rules for chelotropic reactions via conceptual DFT

2010 ◽  
Vol 88 (8) ◽  
pp. 858-865 ◽  
Author(s):  
Pablo Jaque ◽  
José V. Correa ◽  
Frank De Proft ◽  
Alejandro Toro-Labbé ◽  
Paul Geerlings
Keyword(s):  
Density Functional Theory ◽  
Wave Function ◽  
Density Functional ◽  
Pericyclic Reactions ◽  
Dual Descriptor ◽  
Conceptual Density Functional Theory ◽  
Functional Theory ◽  
Linear Path ◽  
Initial Hardness ◽  
Linear And Nonlinear

In our continuous effort to retrieve the Woodward–Hoffmann rules from conceptual density functional theory (DFT), we have examined the last type of pericyclic reactions, i.e., chelotropic reactions. Both the initial hardness response and the dual descriptor have been investigated to predict the allowed and forbidden character for the addition of SO2 to butadiene (4n system) and 1,3,5-hexatriene (4n + 2 system). It is shown that with both electronic descriptors, the conrotatory/disrotatory mode for the linear and nonlinear mechanisms are retrieved based on a density-only approach, free from consideration of orbital and (or) wave function symmetry. The dual descriptor moreover reveals that stabilizing interactions are presented only for the linear path, which can be considered as an overall favourable mechanism for a chelotropic reaction.

scholarly journals Coating of 1.4404 stainless steel by a combination of brazing and nitriding

10.30544/391 ◽  
2018 ◽  
Vol 24 (3) ◽  
pp. 209-218
Author(s):  
Ali Hussein Al-Azzawi ◽  
Peter Baumli
Keyword(s):  
Stainless Steel ◽  
Coating Layer ◽  
Stainless Steel Substrate ◽  
Steel Substrate ◽  
Hard Coating ◽  
Hard Phase ◽  
Hardness Testing ◽  
Nitriding Time ◽  
Metallurgical Bonding ◽  
Initial Hardness

In the current research, surface hardening of 1.4404 stainless steel was investigated. A hard Ni-containing coating was prepared by brazing at 1150 °C using a Ni foil with Si powder. The hardness behavior was increased by nitriding as well. The nitriding experiments were performed at low and high temperatures (460 and 640 °C) for a different period (3 and 6 h). The microstructure and material properties were characterized using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and Micro Vickers hardness testing. Results show that the hard phase and the binding Ni foil were well distributed into the hard layer. The hard coating material was composed of a Si-phases and Ni-containing compound dispersion.After the nitriding, the hardness of the samples was increased with increasing the nitriding time and temperature and increasing the brazing time. The 10 min brazing and 6h nitriding at 640°C resulted in 32% higher hardness than the non-nitride sample.Strong metallurgical bonding is formed between the stainless steel substrate and the coating layer, as well as between the binding Ni foil and the hard phase; because of the mutual diffusion of alloying elements, the hardness of this hard coating was 2 to 3 times higher than the initial hardness of steel substrate.

scholarly journals PENGARUH PEMBERIAN LARUTAN SARI KURMA (PHOENIX DACTYLIFERA L.) DAN LARUTAN FLUOR TERHADAP KEKERASAN EMAIL GIGI SETELAH DIRENDAM DALAM MINUMAN RINGAN BERKARBONASI

2021 ◽  
Vol 2 (1) ◽  
pp. 56-64
Author(s):  
Mety Dwi Putri Eszy ◽  
Afriwardi Afriwardi ◽  
Susi Susi
Keyword(s):  
Tooth Enamel ◽  
Soft Drink ◽  
Surface Hardness ◽  
Phoenix Dactylifera ◽  
Low Ph ◽  
Phoenix Dactylifera L ◽  
Palm Juice ◽  
Significant Difference ◽  
Initial Hardness ◽  
Experimental Laboratory

Soft drink with low pH (5,5) causes tooth erosion. Erosion may result in a decrease in surface hardness of tooth enamel. This research will be used a solution of palm juice and solution of fluoride to increase the surface hardness of tooth enamel. The purpose of this study was to evaluate effect of using a solution of palm juice 100%, 75%, 50%, 25% and APF 1,23% to the surface hardness of tooth enamel. The methode used in this research is the experimental laboratory and were tested for their hardness using Vicker Hardness Tester.Measurement performed three times, initial hardness, after all specimens was soaked in soft drink for 25 hours and were then applied with 100%, 75%, 50%, 25% solution of palm juice dan APF 1,23%. Data was analyzed by using SPSS with Repeated ANOVA.The result showed that a significant decrease in tooth enamel hardness on immersion in carbonated soft drink (p<0,05) and increased hardness of surface enamel after application with 100% solution of palm juice with a mean increase of microhardness 42,91VHN, 38,46 VHN with 75% solution of palm juice, 35,836 VHN with 50% solution of palm juice,29,41 VHN with 25% solution of palm juice dan 23,94 VHN in APF 1,23%.The result of this study is there is no significant difference enamel hardness after applied with 100%, 75%, 50%, 25% solution of palm juice and APF 1,23%.

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