Search results for "engineering.material"

On the role of atomic thermal vibrations in binary-alloy thermodynamics

2001

An ab initio approach is advanced for the thermodynamical properties investigations of disordered binary alloys. Configurational and vibrational degrees of freedom are considered on the microscopic level in the grand partition sum calculations. Summing over the vibrational and configurational states of an alloy is performed within the reference system approach and the collective variables method, respectively. An equation defining the alloy free energy is obtained. The role of the atomic thermal vibrations in the binary-alloy thermodynamics and their relationship with the configurational effects are discussed. Conditions when the configurational and vibrational effects can be treated separa…

Coated interconnects development for high temperature water vapour electrolysis: Study in anode atmospher

2013

International audience; High temperature water vapour electrolysis (HTE) is an efficient technology for hydrogen production. In this context, a commercial stainless steel, K41X (AISI 441), was chosen as interconnect. In a previous paper, the high temperature corrosion and the electrical conductivity were evaluated in both anode (O-2-H2O) and cathode (H-2-H2O) atmosphere at 800 degrees C. In O-2-H2O atmosphere, the formation of a thin chromia protective layer was observed. Nevertheless, the ASR parameter measured was higher than the maximum accepted value. These results, in addition with chromium evaporation measurements, proved that the K41X alloy is not suitable for HTE interconnect applic…

Leaded Bronze Alloy as a Catalyst for the Electroreduction of CO 2

2019

Fabrication and characterization of magnetic FePt nanoparticles prepared by extraction–pyrolysis method

2018

We are grateful to Prof. E. Kotomin for useful discussions. The research leading to these results has received funding from the ERAF (2017) Project, while A. I. Popov thanks IMIS-2 for the funding support.

Investigating the mechanical properties of GeSn nanowires.

2019

Germanium tin (GeSn) has been proposed as a promising material for electronic and optical applications due to the formation of a direct band-gap at a Sn content >7 at%. Furthermore, the ability to manipulate the properties of GeSn at the nanoscale will further permit the realisation of advanced mechanical devices. Here we report for the first time the mechanical properties of GeSn nanowires (7.1-9.7 at% Sn) and assess their suitability as nanoelectromechanical (NEM) switches. Electron microscopy analysis showed the nanowires to be single crystalline, with surfaces covered by a thin native amorphous oxide layer. Mechanical resonance and bending tests at different boundary conditions were use…

Comparison of spring characteristics of titanium-molybdenum alloy and stainless steel

2017

Background Titanium-molybdenum alloy (TMA) and stainless steel (SS) wires are commonly used in orthodontics as arch-wires for tooth movement. However, plastic deformation phenomenon in these arch-wires seems to be a major concern among orthodontists. This study aimed to compare the mechanical properties of TMA and SS wires with different dimensions. Material and Methods Seventy-two wire samples (36 TMA and 36 SS) of three different sizes (19×25, 17×25 and 16×22) were analyzed in vitro, with 12 samples in each group. Various mechanical properties of the wires, including spring-back, bending moment and stiffness were determined using a universal testing machine. Student’s t-test showed statis…

The multi-effects of K2TiF6 additive on the properties of PEO coatings on AZ31 Mg alloy

2020

Abstract Plasma electrolytic oxidation of AZ31 Mg alloy was performed in an alkaline silicate-based solution containing various concentrations of K2TiF6 using unipolar waveform at a constant voltage. The surface morphology of all coatings was rough and contained a micro-pore network, micro-cracks, and granules of oxide compounds in different diameters and micro-pore levels. The coating is composed of MgO, MgF2, Mg2SiO4, SiO2 (amorphous), and TiO2 (crystalline and amorphous) phases. The average thickness of the coatings was increased by adding the K2TiF6, where EDS results showed that a skinny fluoride-rich passive layer forms. With increasing time and reaching the final potential, the TiO2 …

Study of magnesium and aluminum alloys absorption coefficient during Nd:YAG laser interaction

2007

International audience; In laser processes, the absorption factor of laser Nd:YAG by metals plays a very important role. In order to model laser welding, we need to know its evolution during the process. The theoretical calculation does not enable the prediction of the absorption factor in the case of a keyhole mode. It is difficult to predict the effect of plasma and recoil pressure on the shape of the keyhole. In this paper, an integrating sphere is used to determine the absorption factor during the laser process, which is carried out on two types of magnesium alloys (WE43 and RZ5) and an aluminum alloy. We obtain the evolution in time of the absorption factor according to different steps…

2017

Abstract Chromic acid anodizing is important for the corrosion protection of aerospace aluminium alloys. Previous study has demonstrated that SO 4 2 − impurity in the chromic acid affects the film growth on aluminium at a voltage of 100 V. The present work further investigates aluminium and extends the study to industrial anodizing conditions (Bengough-Stuart (B-S) process) and to the AA 2024-T3 alloy. It is shown that SO 4 2 − concentrations between ~ 38–300 ppm reduce the film growth rate for aluminium anodized at 100 V in comparison with an electrolyte than contains ≤ 1.5 ppm SO 4 2 − , whereas ~ 1500–3000 ppm SO 4 2 have an opposite effect and lead to an unstable pore diameter. Under th…

Effect of alloy type and casting technique on the fracture strength of implant-cemented structures.

2010

Objectives: To evaluate the influence of alloy type and casting procedure on the fracture strength (FS) of metallic frameworks for implant-supported fixed prostheses. Study design: Thirty three-unit structures for lower posterior bridges were waxed-up and randomly assigned to two groups (n=15) according to alloy type and casting technique: Group 1 (C): cobalt-chromium cast in a centrifugal machine (TS1, Degussa-Hüls); Group 2 (T): titanium cast in a pressure-differential device (Cyclarc II, Morita). Each structure was cemented onto two prefabricated abutments under a constant seating pressure. After 6 months of water aging, samples were loaded in a static universal testing machine (EFH/5/FR…