Letteratura scientifica selezionata sul tema "R-HiPIMS"

A reactive high-power impulse magnetron sputtering (r-HiPIMS) and a reactive high-power impulse magnetron sputtering combined with electron cyclotron wave resonance plasma source (r-HiPIMS + ECWR) were used for the deposition of p-type CuFexOy thin films on glass with SnO2F conductive layer (FTO). The aim of this work was to deposit CuFexOy films with different atomic ratio of Cu and Fe atoms contained in the films by these two reactive sputtering methods and find deposition conditions that lead to growth of films with maximum amount of delafossite phase CuFeO2. Deposited copper iron oxide films were subjected to photoelectrochemical measurement in cathodic region in order to test the possibility of application of these films as photocathodes in solar hydrogen production. The time stability of the deposited films during photoelectrochemical measurement was evaluated. In the system r-HiPIMS + ECWR, an additional plasma source based on special modification of inductively coupled plasma, which works with an electron cyclotron wave resonance ECWR, was used for further enhancement of plasma density ne and electron temperature Te at the substrate during the reactive sputtering deposition process. A radio frequency (RF) planar probe was used for the determination of time evolution of ion flux density iionflux at the position of the substrate during the discharge pulses. Special modification of this probe to fast sweep the probe system made it possible to determine the time evolution of the tail electron temperature Te at energies around floating potential Vfl and the time evolution of ion concentration ni. This plasma diagnostics was done at particular deposition conditions in pure r-HiPIMS plasma and in r-HiPIMS with additional ECWR plasma. Generally, it was found that the obtained ion flux density iionflux and the tail electron temperature Te were systematically higher in case of r-HiPIMS + ECWR plasma than in pure r-HiPIMS during the active part of discharge pulses. Furthermore, in case of hybrid discharge plasma excitation, r-HiPIMS + ECWR plasma has also constant plasma density all the time between active discharge pulses ni ≈ 7 × 1016 m−3 and electron temperature Te ≈ 4 eV, on the contrary in pure r-HiPIMS ni and Te were negligible during the “OFF” time between active discharge pulses. CuFexOy thin films with different atomic ration of Cu/Fe were deposited at different conditions and various crystal structures were achieved after annealing in air, in argon and in vacuum. Photocurrents in cathodic region for different achieved crystal structures were observed by chopped light linear voltammetry and material stability by chronoamperometry under simulated solar light and X-ray diffraction (XRD). Optimization of depositions conditions results in the desired Cu/Fe ratio in deposited films. Optimized r-HiPIMS and r-HiPIMS + ECWR plasma deposition at 500 °C together with post deposition heat treatment at 650 °C in vacuum is essential for the formation of stable and photoactive CuFeO2 phase.

One of the main problems in ships is corrosion, which reduces the lifetime usage of ship parts and increases maintenance costs. Ceramic coatings can contribute to solving this situation. Zirconium nitrides obtained by reactive unbalanced magnetron sputtering technology are largely reported as coatings with high corrosion resistance. The present study used high-power impulse magnetron sputtering in a reactive atmosphere (R-HiPIMS), varying the nitrogen amount. SEM, EDS, XRD, AFM, and contact angle measurements were used to assess the obtained coatings’ performance. Corrosion resistance was evaluated using electrochemical impedance spectroscopy (EIS) (up to 168 h exposure) and potentiodynamic polarization (PP) in NaCl (3.5% wt.—“artificial seawater”) solution. According to the results, cross section micrographs showed strong densification of ZrN films regardless of the nitrogen amount. Besides, nitrogen increases during deposition influenced the drop of applied peak power (Pp) to the target and, consequently, influenced other film properties, such as roughness, wettability, and corrosion resistance. PP and EIS tests demonstrate the protective behavior of films under artificial seawater exposure. The results prove that the implementation of HiPIMS technology to obtain ZrN films could contribute to increasing the corrosion resistance of coated ship metallic parts and, hence, help maritime transportation to reduce maintenance time and cost.

The vanadium dioxide films were deposited by reactive high-power impulse magnetron sputtering for different plasma emission intensity at the substrate temperature of 310 °C. The setpoint of plasma emission intensity was controlled by a PID controller with plasma-emission-monitoring. The vanadium dioxide films characteristics were measured by optical spectrophotometer, X-ray diffraction and electrical source meter.

A reactive high-power impulse magnetron sputtering system (HiPIMS) working in Ar + H2S gas mixture was investigated as a source for the deposition of iron sulfide thin films. As a sputtering material, a pure Fe target was used. Plasma parameters in this system were investigated by a time-resolved Langmuir probe, radio-frequency (RF) ion flux probe, quartz crystal monitor modified for measurement of the ionized fraction of depositing particles, and by optical emission spectroscopy. A wide range of mass flow rates of reactive gas H2S was used for the investigation of the deposition process. It was found that the deposition rate of iron sulfide thin films is not influenced by the flow rate of H2S reactive gas fed into the magnetron discharge although the target is covered by iron sulfide compound. The ionized fraction of depositing particles decreases from r ≈ 40% to r ≈ 20% as the flow rate of H2S, QH2S, changes from 0 to 19 sccm at the gas pressure around p ≈ 1 Pa in the reactor chamber. The electron concentration ne measured by the Langmuir probe at the position of the substrate decreases over this change of QH2S from 1018 down to 1017 m−3

Abstract Purpose Many low-middle income countries (LMIC) suffer from chronic shortages of resources that inhibit the implementation of effective breast cancer screening programs. Advanced breast cancer rates in the U.S. Affiliated Pacific Islands substantially exceed that of the United States. We propose the use of portable breast ultrasound coupled with artificial intelligence (AI) algorithms to assist non-radiologist field personnel in real-time field lesion detection, classification, and biopsy, as well as determination of breast density for risk assessment. In this study, we examine the ability of an AI algorithm to detect and describe breast cancer lesions in clinically-acquired breast ultrasound images in 40,000 women participating in a Hawaii screening program. Materials and Methods The Hawaii and Pacific Islands Mammography Registry (HIPIMR) collects breast health questionnaires and breast imaging (mammography, ultrasound, and MRI) from participating centers in Hawaii and the Pacific and links this information to the Hawaii Tumor Registry for cancer findings. From the women with either screening or diagnostic B-mode breast ultrasound exams, we selected 3 negative cases (no cancer) for every positive case matched by age, excluding Doppler and elastography images. The blinded images were read by the study radiologist to delineate all lesions and describe in terms of the BI-RADS lexicon. These images were split by woman into training (70%), validation and hyperparameter selection (20%) and testing (20%) subsets. An AI model was fine-tuned for lesion and BI-RADS category classification from a Detectron2 framework [1] pre-trained on the COCO Instance Segmentation Dataset [2]. Model performance was evaluated by computation of precision and sensitivity percentages, as well as Area under the Receiver Operator Curve (AUROC). Detections were considered positive if they overlapped a ground truth lesion delineation by at least 50% (Intersection over Union = 0.5), and a maximum of 4 detections were generated for each image. Timing experiments were run on a GPU-enabled (Nvidia Tesla V100) machine on unbatched images. Results Over the 10-year observation period, we identified 5,214 women with US images meeting our criterion. Of these, 111 were diagnosed with malignant breast cancer and 333 were selected as non-cases for a total of 444 women. These 444 women had a total of 4,623 ultrasound images with 2,028 benign and 1,431 malignant lesions identified by the study radiologist. For cancerous lesions, the AI algorithm had 8% precision at a sensitivity of 90% on the testing set. For benign lesions, a sensitivity of 90% resulted in 5% precision on the testing set. The AUROC for bounding box detections of cancerous lesions was 0.90. The AUROC for bounding box detections of benign lesions was 0.87. The model made predictions at a rate of 25 frames/second time (38.7 milliseconds per image). Conclusion Detection, segmentation, and cancer classification of breast lesions are possible in clinically-acquired ultrasound images using AI. Based on our timing experiments, the model is capable of detecting and classifying lesions in real-time during ultrasound capture. Model performance is expected to improve as more data becomes available for training. Future work would involve further fine-tuning of the model on portable breast ultrasound images and increasing model evaluation speed in order to assess utility in low-resource populations [1] Wu Y, Kirillov A, Massa F, Lo W-Y, Girshick R. Detectron2. https://github.com/facebookresearch/detectron2. [2] Lin T-Y, Maire M, Belongie S, et al. Microsoft COCO: Common Objects in Context. Computer Vision – ECCV 2014. Springer International Publishing; 2014:740-755. Citation Format: Arianna Bunnell, Dustin Valdez, Thomas Wolfgruber, Aleen Altamirano, Brenda Hernandez, Peter Sadowski, John Shepherd. Artificial Intelligence Detects, Classifies, and Describes Lesions in Clinical Breast Ultrasound Images [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-04-05.

Cette thèse s’inscrit dans la problématique du dépôt de couches minces en procédé réactif de pulvérisation cathodique magnétron pulsée haute puissance (R-HiPIMS_reactive high power impulse magnetron sputtering). Pour pouvoir implémenter ce procédé sur des systèmes industriels, sa complexité nécessite d’être capable de le contrôler au cours du temps de manières simple et efficace car, entre autres, le profil de la piste de pulvérisation de la cible (Ti) change inévitablement durant son utilisation. L’objectif principal de cette thèse est donc de proposer une méthode de contrôle de l’épaisseur de films de type TiO₂ en mélange gazeux Ar/O₂. Une étude préparatoire des effets de la puissance HiPIMS, de la durée de décharge, de la teneur en oxygène et de la température du porte-substrat a alors été menée. Le plasma a été caractérisé par des mesures de spectroscopie optique d’émission, de spectrométrie de masse et les caractéristiques courant-tension de la décharge. Les couches minces ont été analysées par DRX, MEB et profilométrie. Une méthode de contrôle de l’épaisseur des dépôts, couplant la spectroscopie optique d’émission (SOE) avec la mesure du courant intégré durant la décharge (Iint) a ensuite été mise au point. Le signal SOE moyenné dans le temps (TA_SOE) du titane neutre a été divisé par Iint afin de tenir compte des variations de la fonction de distribution en énergie des électrons. Le rapport signal TA_SOE(Ti)/Iint a finalement été corrélé à l’épaisseur des dépôts en fonction de différents paramètres, dont le % O₂, la durée de décharge, l’usure de la cible et la température du porte-substrat
The growth of thin layers in reactive-high power impulse magnetron sputtering (R-HiPIMS) process is the general framework of this PhD. The coating industry needs a simple and reliable method to track the evolution of deposits over time because, among other reasons, the racetrack shape certainly changes during the sputtering process. The main goal of this PhD is to develop a reliable tool devised to control TiO₂ thin layer thickness in R-HiPIMS deposition process. Preliminary studies of the influence of O₂ content in the Ar/O₂ gas mixture, the mean pulse power, the pulse width and the substrate-holder temperature were performed. The plasma was characterized by optical emission spectroscopy (OES), mass spectrometry and current-voltage characteristics of the discharge. Thin films were analysed by XRD, SEM and profilometry. From combined analyses of Ti emission line intensity, integrated discharge current and deposited TiO₂ coating thickness, it is established that plasma diagnostics can be used effectively to control the deposition rate. Indeed, dividing the time average emission line intensity (TA_OES) by the integrated current (Iint) leads to obtain the TA_OES signal(Ti)/Iint ratio, which allows eliminating the effect of any variation of the electron energy distribution function. In all our investigated conditions (% O₂, pulse width, the target erosion profile and the substrate-holder temperature), the TA_OES signal(Ti)/Iint ratio seems to be in good agreement with the thickness. Thus, it seems that this ratio well reflects the titanium species density which contributes to the deposits

Dieser VDI-Bericht ist ausschließlich als PDF-Dokument erschienen! Inhalt Prozessauslegung und Überwachung Integrierte CAD/CAM Software für Industrie 4.0 1 R. Keiser, SolidCAM, Hörstel Werkzeuge und Verfahren für die wirtschaftliche und innovative Zerspanung VHM-Fräswerkzeuge zum Dynamischen Fräsen – Voraussetzungen und Besonderheiten 11 P. Binder, Walter AG, Tübingen Innovative Konzeptentwicklung für eine effiziente Bohrbearbeitung – Wendeschneidplattenbohrkonzept für Bohrtiefen bis zu 7xD 15 I. Terwey, Sandvik Tooling Deutschland GmbH, Düsseldorf Schneidplatten – geht’s noch kleiner und schneller? 19 K. Brenner, ISCAR Germany GmbH, Ettlingen Hochleistungs-Schneidstoffe und Beschichtungen HiPIMS – Beschichtungen von heute und morgen – HiPIMS – Die PVD-Beschichtungstechnologie von morgen? 31 M. Weigand, CemeCon AG, Würselen Hybride Beschichtungsprozesse für anwendungsbezogene PVD-Schichten 35 H. Frank, F. Barthelmä, H. Joost, GFE – Gesellschaft für Fertig...