Publications de Ayat Karimi | EPFL Graph Search

Mechanical signatures of degradation of the photovoltaic perovskite CH3NH3PbI3 upon water vapor exposure

László Forró, Endre Horvath, Wanda Andreoni, Bálint Náfrádi, Massimo Spina, Ayat Karimi

We report on the mechanical properties of CH3NH3PbI3 photovoltaic perovskite measured by nanoindentation. The Young's modulus (E) of the pristine sample is 20.0 +/- 1.5GPa, while the hardness (H) is 1.0 +/- 0.1GPa. Upon extended exposure to water vapor, bo ...

2017

Structural and mechanical properties of Nb-1 (-) xTixN thin films deposited by rf magnetron sputtering

Ayat Karimi, Alireza Karimi, Daniela Dumitriu La Grange

Nb1-xTixNy thin films with different nitrogen contents (0.5 < y < 1.2) and Nb/Ti ratios (0

Elsevier2016

NbTiN thin films deposited by hybrid HiPIMS/DC magnetron co-sputtering

Rosendo Sanjines, Alireza Karimi, Ayat Karimi, Samy Adjam, Daniela Dumitriu La Grange

Nb1 - xTixNy thin films (with 0

Elsevier Science Sa2016

A novel synthetic strategy for bioinspired functionally graded nanocomposites employing magnetic field gradients

Yves Leterrier, Ayat Karimi, Tommaso Nardi

In order to mimic the complex architecture of many bio-materials and synthesize composites characterized by continuously graded composition and mechanical properties, an innovative synthetic strategy making use of magnetic field gradients and based on the ...

2014

Formation of (113) texture in fcc nitride thin films and its influence on the film properties

Ayat Karimi, Alireza Karimi, Akshath Raghu Shetty

This work presents a study of XRD measurements on the development of the (113) preferential orientation with film thickness for Ti0.67Al0.33N films grown on Si(100) substrates by pulsed DC magnetron sputtering. The buildup of (113) texture was observed usi ...

Elsevier Science Sa2013

Texture mechanisms and microstructure of biaxial thin films grown by oblique angle deposition

Ayat Karimi, Alireza Karimi, Akshath Raghu Shetty

In order to understand the texture formation mechanism in thin films grown under oblique angle deposition (OAD), TiAlN films were deposited at room temperature (RT) under various incident angles. We show that both in-plane and out-of-plane crystallographic ...

Wiley-V C H Verlag Gmbh2012

Evaluation of the hydrodynamic pressure of cavitation impacts from stress-strain analysis and geometry of individual pits

Ayat Karimi, Davide Carnelli, Jean-Pierre Franc

The present paper focuses on the development of an inverse procedure able to infer the hydrodynamic pressure distribution acting on the material surface and responsible for the creation of the cavitation pit based on the stress in a cavitation pit and its ...

2012

Application of spherical nanoindentation to determine the pressure of cavitation impacts from pitting tests

Ayat Karimi, Davide Carnelli, Jean-Pierre Franc

This article focuses on the use of spherical nanoindentation measurements to estimate the pressure of cavitation impacts and its statistical distribution. Indeed, nanoindentation techniques are supposed to represent an effective tool in this field due to t ...

Cambridge University Press2012

Material and velocity effects on cavitation erosion pitting

Ayat Karimi, Jean-Pierre Franc

Cavitation erosion during the incubation period was investigated via pitting tests conducted on three different materials: an Aluminum alloy, a Nickel Aluminum Bronze alloy and a Duplex Stainless Steel. Pitting tests were conducted in a cavitation tunnel i ...

2012

Scaling study of cavitation pitting from cavitating jets and ultrasonic horns

Ayat Karimi, Jean-Pierre Franc

Cavitation erosion prediction and characterization of cavitation field strength are of interest to industries suffering from cavitation erosion detrimental effects. One means to evaluate cavitation fields and materials is to examine pitting rates during th ...

Elsevier Science Sa2012