Mechanical and barrier properties of MOCVD processed alumina coatings on Ti6Al4V titanium alloy

This study focuses on the implementation of different aluminum oxide coatings processed by metal-organic chemical vapor deposition from aluminum tri-isopropoxide on commercial Ti6Al4V titanium alloy to improve its high temperature corrosion resistance. Films grown at 350 °C and at 480 °C are amorphous and correspond to formulas AlOOH, and Al2O3, respectively. Those deposited at 700 °C are composed of γ-Al2O3 nanocrystals dispersed in a matrix of amorphous alumina. Their mechanical properties and adhesion to the substrates were investigated by indentation, scratch and micro tensile tests. Hardness and rigidity of the films increase with increasing deposition temperature. The hardness of the coatings prepared at 350 °C and 480 °C is 5.8 ± 0.7 GPa and 10.8 ± 0.8 GPa respectively. Their Young's modulus is 92 ± 8 GPa (350 °C) and 155 ± 6 GPa (480 °C). Scratch tests cause adhesive failures of the films grown at 350 °C and 480 °C whereas cohesive failure is observed for the nanocrystalline one, grown at 700 °C. Micro tensile tests show a more progressive cracking of the latter films than on the amorphous ones. The films allow maintaining good mechanical properties after corrosion with NaCl deposit during 100 h at 450 °C. After corrosion test only the film deposited at 700 °C yields an elongation at break comparable to that of the as processed samples without corrosion. The as established processing–structure–properties relation paves the way to engineer MOCVD aluminum oxide complex coatings which meet the specifications of the high temperature corrosion protection of titanium alloys with regard to the targeted applications

A study on the dispersion, preparation, characterization and photo-degradation of polypropylene traced with rare earth oxides

This research work deals with the effect of rare earth oxides on the PP matrix with respect to the thermal and mechanical properties and to the photo-degradation under UV irradiation exposure. The rare earth oxides are used as tracers for the identification of polymer materials, in order to have an economically efficient recycling and high speed automatic sorting of plastic wastes. The addition of 0.1 wt% of such particles of a micrometric size has a minor effect on the mechanical and thermal properties of the traced materials, as well as on the photo-degradation of the polymer after UV irradiation exposure. For 1 wt% tracer content, before UV irradiation treatment, the melting and crystallization temperatures as well as the thermal stability of the PP matrix are slightly increased, whereas the elongation at break decreases from 10 to 50% for a cross-head speed of 250 mm/min. However, the addition of 1 wt% of CeO2 improves the photo-degradation resistance of the PP matrix to UV exposure due to the UV light screening effects offered by these particles. The SEM images together with the results obtained from image processing show a homogenous dispersion of tracers in the PP matrix.This research work deals with the effect of rare earth oxides on the PP matrix with respect to the thermal and mechanical properties and to the photo-degradation under UV irradiation exposure. The rare earth oxides are used as tracers for the identification of polymer materials, in order to have an economically efficient recycling and high speed automatic sorting of plastic wastes. The addition of 0.1 wt% of such particles of a micrometric size has a minor effect on the mechanical and thermal properties of the traced materials, as well as on the photo-degradation of the polymer after UV irradiation exposure. For 1 wt% tracer content, before UV irradiation treatment, the melting and crystallization temperatures as well as the thermal stability of the PP matrix are slightly increased, whereas the elongation at break decreases from 10 to 50% for a cross-head speed of 250 mm/min. However, the addition of 1 wt% of CeO2 improves the photo-degradation resistance of the PP matrix to UV exposure due to the UV light screening effects offered by these particles. The SEM images together with the results obtained from image processing show a homogenous dispersion of tracers in the PP matrix

Laser welding of titanium alloys with an Yb: YAG sisk source

International audienceIn this paper, the laser welding of thin titanium sheet in a butt joint configuration are investigated using a continuous Yb: YAG disk source, with high beam quality and a particular fiber configuration, enable to provide a broad range of beam diameters with different intensity distribution. The thermal efficiency of the laser process is discussed as a function of the fiber type. The weldability results for the CP Ti grade 2 and the Ti-6Al-4V titanium alloy are expressed in terms of full penetration, and correct bead geometry (NF L06-395-2000). Full penetration welds are easily achieved with the core fiber, but the outer fiber produces welds with limited geometric defects. Butt joints microstructure consists of an acicular α phase in the fusion zone for CP Ti, and a martensitic α’ phase for the Ti-6Al-4V alloy. Tensile test results confirm a similar or slightly higher joint strength for the full penetration welds, compared with the parent metal

A study on the dispersion, preparation, characterization and photo-degradation of polypropylene traced with rare earth oxides

This research work deals with the effect of rare earth oxides on the PP matrix with respect to the thermal and mechanical properties and to the photo-degradation under UV irradiation exposure. The rare earth oxides are used as tracers for the identification of polymer materials, in order to have an economically efficient recycling and high speed automatic sorting of plastic wastes. The addition of 0.1 wt% of such particles of a micrometric size has a minor effect on the mechanical and thermal properties of the traced materials, as well as on the photo-degradation of the polymer after UV irradiation exposure. For 1 wt% tracer content, before UV irradiation treatment, the melting and crystallization temperatures as well as the thermal stability of the PP matrix are slightly increased, whereas the elongation at break decreases from 10 to 50% for a cross-head speed of 250 mm/min. However, the addition of 1 wt% of CeO2 improves the photo-degradation resistance of the PP matrix to UV exposure due to the UV light screening effects offered by these particles. The SEM images together with the results obtained from image processing show a homogenous dispersion of tracers in the PP matrix.ANR TRIPTI

Yb: YAG laser welding of aeronautical alloys

Interest in the use of laser technology is growing in the aeronautical sector. The implementation of new Yb: YAG solid laser sources and new optical generations (dynamic focal length; 2in1 fiber: Fiber core and ring core) offers advantages in terms of quality, accuracy, reproducibility and weld dimensions. The LASER beam Yb: YAG of these new sources is generated, no longer from a bar of yttrium aluminum garnet but from a disk. Moreover, a top-hat shaped power distribution and a top-hat shaped power distribution with a sharply limited recess in the center (ring structure) may be at the focal point using respectively the inner fiber and the coaxial fiber. These technological innovations offer new possibilities for cutting and welding of sheet metal parts. The welding domains of EN AW-6061 aluminum alloy, Commercial Purity Titanium - Grade 2 (T40), AISI 321 stainless steel alloy, nickel based Hastelloy X and Inconel 625 and cobalt based Haynes 188 superalloys are defined according to process parameters such as power density, focal diameter, welding speed and fiber type. Optimal welding parameters are determined for each alloy. The evolution of the microstructures and the mechanical properties of each zone of the welds are explained according to the power density, the heat input energy and the welding speed

Elaboration and Characterization of Traced Polypropylene with Rare Earth Oxides for Automatic Identification and Sorting of End-of-Life Plastics

Abstract The rare earth oxides can be used as tracers for the identification of polymer materials. This study focused on the detection of these particles and their effects on the mechanical and thermal properties of polypropylene (PP). A new method was carried out to increase the sorting selectivity of PP during end of life recycling process and to improve the efficiency of sorting and its high speed identification. The tests were realized in a test system device which allows the collection of static measurements of the samples spectrum through the use of energy dispersive X-ray fluorescence technology. Five of the seven tracers tested are clearly visible and distinguishable from the background sample by their Ka1 energy line at concentration levels of 0.1 and 0.145 wt%. For the two remaining tracers, their Ka1 energy lines come out at the same domain of energy as the source. Dispersion of rare earth oxides at 0.1 and 1 wt% do not have a significant impact on the crystallization and melting temperature as well as on the temperature of maximum decomposition rate. The addition of 1 wt% of rare earth oxides leads to a slight increase of the flexural modulus, whereas the addition of 0.1 and 1 wt% causes a decrease of the elongation at break. SEM images show a homogenous dispersion of tracers in the PP matrix.ANR TRIPTIC RECORD ADEME RENAULT SITA VEOLIA ENVIRONNEMEN

Synergy between intraperitoneal aerosolization (PIPAC) and cancer nanomedicine : cisplatin-loaded polyarginine-hyaluronic acid nanocarriers efficiently eradicate peritoneal metastasis of advanced human ovarian cancer

Intra-abdominal dissemination of peritoneal nodules, a condition known as peritoneal carcinomatosis (PC), is typically diagnosed in ovarian cancer patients at the advanced stages. The current treatment of PC consists of perioperative systemic chemotherapy and cytoreductive surgery, followed by intra-abdominal flushing with solutions of chemotherapeutics such as cisplatin and oxaliplatin. In this study, we developed cisplatin-loaded polyarginine-hyaluronic acid nanoscale particles (Cis-pARG-HA NPs) with high colloidal stability, marked drug loading efficiency, unimpaired biological activity, and tumor-targeting ability. Injected Cis-pARG-HA NPs showed enhanced antitumor activity in a rat model of PC, compared to injection of the free cisplatin drug. The activity of Cis-pARG-HA NPs could even be further improved when administered by an intra-abdominal aerosol therapy, referred to as pressurized intraperitoneal aerosol chemotherapy (PIPAC). PIPAC is hypothesized to ensure a more homogeneous drug distribution together with a deeper drug penetration into peritoneal tumor nodules within the abdominal cavity. Using fluorescent pARG-HA NPs, this enhanced nanoparticle deposit on tumors could indeed be observed in regions opposite the aerosolization nozzle. Therefore, this study demonstrates that nanoparticles carrying chemotherapeutics can be synergistically combined with the PIPAC technique for IP therapy of disseminated advanced ovarian tumors, while this synergistic effect was not observed for the administration of free cisplatin

Tiberian Hebrew finite verbal morphology

Following McGinnis (1995), who used a Distributed Morphology (DM) approach (Halle & Marantz 1993; 1994) within a minimalist syntactic framework (Chomsky 1995), I analyze the distribution of morphological elements referring to phi-features in Tiberian Hebrew finite verbs in terms of feature checking. In the Imperfect and relaxed verb forms, phi-features are marked by prefixes and suffixes; in some cases the same feature is marked in both types of affix on the same form. In contrast, the phi-feature associated with all other inflected forms are marked by suffixes alone. I assume that features associated with inflectional suffixes are checked in the syntax and do not require word-internal checking, but the features associated with the Imprefect must be checked in both the syntactic and morphological components. This additional round of checking results in a structure where a copy of the features is merged/adjoined with V, both of which may be spelled out. The close structural association of the adjoined Imperfect phi-features with V also counts for the observation that the imperfect inflectional prefixes are the only phi-referring morphological elements incorporated into TH stems

Elaboration and Characterization of Traced Polypropylene with Rare Earth Oxides for Automatic Identification and Sorting of End-of-Life Plastics

Abstract The rare earth oxides can be used as tracers forthe identification of polymer materials. This study focusedon the detection of these particles and their effects on themechanical and thermal properties of polypropylene (PP).A new method was carried out to increase the sortingselectivity of PP during end of life recycling process and toimprove the efficiency of sorting and its high speed identification.The tests were realized in a test system devicewhich allows the collection of static measurements of thesamples spectrum through the use of energy dispersiveX-ray fluorescence technology. Five of the seven tracerstested are clearly visible and distinguishable from thebackground sample by their Ka1 energy line at concentrationlevels of 0.1 and 0.145 wt%. For the two remainingtracers, their Ka1 energy lines come out at the same domainof energy as the source. Dispersion of rare earth oxides at0.1 and 1 wt% do not have a significant impact on thecrystallization and melting temperature as well as on thetemperature of maximum decomposition rate. The additionof 1 wt% of rare earth oxides leads to a slight increase ofthe flexural modulus, whereas the addition of 0.1 and 1wt% causes a decrease of the elongation at break. SEMimages show a homogenous dispersion of tracers in the PPmatrix.International audienceAbstract The rare earth oxides can be used as tracers forthe identification of polymer materials. This study focusedon the detection of these particles and their effects on themechanical and thermal properties of polypropylene (PP).A new method was carried out to increase the sortingselectivity of PP during end of life recycling process and toimprove the efficiency of sorting and its high speed identification.The tests were realized in a test system devicewhich allows the collection of static measurements of thesamples spectrum through the use of energy dispersiveX-ray fluorescence technology. Five of the seven tracerstested are clearly visible and distinguishable from thebackground sample by their Ka1 energy line at concentrationlevels of 0.1 and 0.145 wt%. For the two remainingtracers, their Ka1 energy lines come out at the same domainof energy as the source. Dispersion of rare earth oxides at0.1 and 1 wt% do not have a significant impact on thecrystallization and melting temperature as well as on thetemperature of maximum decomposition rate. The additionof 1 wt% of rare earth oxides leads to a slight increase ofthe flexural modulus, whereas the addition of 0.1 and 1wt% causes a decrease of the elongation at break. SEMimages show a homogenous dispersion of tracers in the PPmatrix