Influence of different process parameters on deformation velocity in laser shock forming

In laser shock forming TEA-CO_2-laser induced shock waves are used to form metal foils, such as aluminum or copper. The process utilizes an initiated plasma shock wave on the target surface, which leads to a forming of the foil. Several pulses can be applied at one point in order to achieve a high forming degree without increasing the energy density beyond the ablation limit. During the process, pressure peaks in range of MPa can be achieved. In this article, the dependence of deformation velocity in laser shock forming on various materials as well as laser pulse intensities was determined experimentally for a laser shock bending process. In order to categorize these influences a theoretical model for deformation velocity based on the energy balance is proposed, which allows the evaluation of the influencing variables

Forming Behaviour in Laser Shock Drawing

Through the continuing trend of miniaturization new cost efficient and fast methods for processing small parts are required. In this paper a new non-mechanical process for the forming process of micro deep drawing is presented. This new deep drawing process utilizes a laser initiated plasma shock wave at the target, which forms the sheet. Several pulses can be applied at one point and therefore high forming degrees can be reached without increasing the energy density. In this paper the pressure of the shock wave is measured in order to enable optimizations of the process in future. Furthermore a distribution of the thickness over the deep drawn cups will be introduced. Finally laser deep drawing of samples made out of Al99.5, Cu and stainless steel sheet metal with thicknesses of 20 µm and 50 µm are shown

Corrosion and wear behaviour of alumina coatings obtained by various methods

Alumina coatings are widely used in a range of industrial applications to improve corrosion protection, wear and erosion resistance and thermal insulation of metallic surfaces. From various efficient and adjustable processes refined alumina surfaces with long-term use are obtained. It can be seen that cost-efficient arc-sprayed Al coatings post-treated by plasma-electrolytic oxidation (PEO) form Al₂O₃-layers with remarkable corrosion protection, hardness, bonding strength and abrasion resistance as well as extended service time. The properties of these coatings are compared to alumina coatings obtained by flame spraying and atmospheric plasma spraying.Покриви на основі оксиду алюмінію широко використовують у промисловості для поліпшення корозійного захисту, зносо- та ерозійної тривкості, а також теплоізлояції металевих поверхонь. Різними методами отримано удосконалені покриви. Показано, що економічно ефективні алюмінієві покриви, сформовані методом електродугового розпилення, а потім оброблені плазмово-електролітичним оксидуванням, утворюють шари Al₂O₃ з високими антикорозійними характеристиками, твердістю, силою зчеплення та абразивною тривкістю і продовженим ресурсом роботи. Порівняно їх властивості з покривами на основі оксиду алюмінію, одержаними методами полуменевого та атмосферного плазмового розпилення.Покрытия на основе оксида алюминия часто применяют в промышленности для улучшения коррозионной защиты, износо- и эрозионной стойкости, а также теплоизлояции металлических поверхностей. Различнымы методами получены усовершенствованные покрытия. Показано, что экономически эффективные алюминиевые покрытия, сформированные методом электродугового распыления, а потом обработаные плазменно-электролитическим оксидированием, образуют слои Al₂O₃ с высокими антикоррозионными характеристиками, твердостью, силой сцепления, абразивной стойкостью и длительным ресурсом работы. Сравнены их свойства с покрытиями на основе оксида алюминия, полученными методами пламенного и атмосферного плазменного распыления

Auditory verbal hallucinations and childhood trauma subtypes across the psychosis continuum:a cluster analysis

Introduction: A strong link between voice-hearing experience and childhood trauma has been established. The aim of this study was to identify whether there were unique clusters of childhood trauma subtypes in a sample across the clinical spectrum of auditory verbal hallucinations (AVH) and to examine clinical and phenomenological features across these clusters. Methods: Combining two independent international datasets (the Netherlands and Australia), childhood trauma subtypes were examined using hierarchical cluster analysis. Clinical and phenomenological characteristics were compared across emerging clusters using MANOVA and chi-squared analyses. Results: The total sample (n = 413) included 166 clinical individuals with a psychotic disorder and AVH, 122 non-clinical individuals with AVH and 125 non-clinical individuals without AVH. Three clusters emerged: (1) low trauma (n = 299); (2) emotion-focused trauma (n = 71); (3) multi-trauma (n = 43). The three clusters differed significantly on their AVH ratings of amount of negative content, with trend-level effects for loudness, degree of negative content and degree of experienced distress. Furthermore, perceptions of voices being malevolent, benevolent and resistance towards voices differed significantly. Conclusion: The data revealed different types of childhood trauma had different relationships between clinical and phenomenological features of voice-hearing experiences. Thus, implicating different mechanistic pathways and a need for tailored treatment approaches

Cellulosic films obtained from the treatment of sugarcane bagasse fibers with N -methylmorpholine- N -oxide (NMMO)

Ethanol/water organosolv pulping was used to obtain sugarcane bagasse pulp that was bleached with sodium chlorite. This bleached pulp was used to obtain cellulosic films that were further evaluated by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). A good film formation was observed when temperature of 74 °C and baths of distilled water were used, which after FTIR, TGA, and SEM analysis indicated no significant difference between the reaction times. The results showed this to be an interesting and promising process, combining the prerequisites for a more efficient utilization of agro-industrial residues.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), (CNPq), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brazil; Fundação para a Ciência e a Tecnologia (FCT) and CEMU