Two-stage potassium test turbine. Volume 1 - Fluid dynamic design and performance

Two stage turbine suitable for use in wet potassium vapor at temperatures of 1400 to 1600 deg

Review Article: Rethinking Holder

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68947/2/10.1177_096394709800700104.pd

Standardized emission quantification and control of costs for environmental measures

Laser welding and soldering are important industrial joining processes. As is known, LGACs (Laser Generated Air Contaminants) cause costs for environmental measures during production of complex metallic components (steel, aluminium, magnesium, alloys). The hazardous potential of such processes has been assessed by analyzing the specific emissions with respect to relevant threshold limit values (TLVs). Avoiding and controlling emissions caused by laser processing of metals or metal composites is an important task. Using the experimental results, the planning of appropriate exhaust systems for laser processing is facilitated significantly. The costs quantified for environmental measures account for significant percentages of the total manufacturing costs

Influence of the laser and its scan width in the LDNA surfacing process

The novel laser-assisted double-wire non-transferred arc (LDNA) surfacing process that melts two consumable wires with an arc between them and uses a laser to guide the process has shown very promising results. Investigations show that it is possible to create single seams with a complete bond and low dilution at a deposition rate of 7.5 kg/h. In case of multiple seams, joint defects might be formed between the seams due to unfavourable seam geometry. In this paper, results on the optimization of this geometry with an adapted laser scan width are presented. An average connection angle of 93 degrees has been achieved on the side of the weld, where additional seams are placed. It is expected that with these results multiple seams can be welded without producing joint defects, thus leading to an intact layer

BFTT project: Al cans recycling processing using a lost cost technology

Presentation of final project repor

Untersuchungen zum Ultraschallschweißen von Gasdiffusionsschichten mit graphithaltigem Gasverteiler in Brennstoffzellen

Die Brennstoffzellen stellen aufgrund ihrer hohe Wirkungsgrade und Flexibilität eine erfolgsversprechende Energiequelle für die Zukunft dar. Bisher werden die Brennstoffzellenkomponenten mittels kraftschlüssiger Verbindung zusammengepresst. Während des Brennstoffzellenbetriebes befinden sich die größten ohmschen Verluste an der Oberfläche zwischen der Gasverteilerplatte und der Gasdiffusionschicht (GDL). Nachstehend werden die ersten grundlegenden Untersuchungen zum Fügen hochgefüllter Graphit-Compounds mit thermoplastischem Binder und der Gasdiffusionsschicht mittels Ultraschallschweißen gezeigt. Dieses soll den Kontaktwiderstand zwischen der graphithaltigen Gasverteilerplatte und der GDL in einer NT-PEM-Brennstoffzelle reduzieren, die Montage des Stacks vereinfachen unter der Bedingung, dass die zugefügten Ultraschall-Longitudinalwellen die Funktionalität der GDL nicht beeinträchtigen

Influence of welding current and focal position on the resonant absorption of laser radiation in a TIG welding arc

The work presents the influence of welding current and focal position on the resonant absorption of diode laser radiation in a TIG welding arc. The laser beam is guided perpendicular to the electrical arc to avoid an interaction with the electrodes. Laser power measurements have shown a reduction of the measured laser power up to 18 % after passing the electrical arc. This reduction results from the interaction of argon shielding gas atoms and laser radiation at 810.4 nm and 811.5 nm. The interaction is strongly affected by the adjusted welding current and the adjustment of the laser beam and the electrical arc. Lowering the welding current or shifting the laser beam out of the centerline of the electrical arc reduces the ionization probability. An increased ionization is necessary to decrease the resistance of the electrical arc

Characteristics of joining and hybrid composite forging of aluminum solid parts and galvanized steel sheets

In lightweight construction, light metals like aluminum are used in addition to high-strength steels. However, a welded joint of aluminum and steel leads to the precipitation of brittle, intermetallic phases and contact corrosion. Nevertheless, to use the advantages of this combination in terms of weight saving composite hybrid forging has been developed. In this process, an aluminum solid part and a steel sheet were formed in a single step and joined at the same time with zinc as brazing material. For this purpose, the zinc was applied by hot dipping on the aluminum in order to produce a connection via this layer in a forming process, under pressure and heat. Due to the formed intermediate layer of zinc, the formation of the Fe-Al intermetallic phases and the contact corrosion are excluded. By determining the mathematical relationships between joining parameters and the connection properties the strength of a specific joint geometry could be adjusted to reach the level of conventional joining techniques. In addition to the presentation of the joint properties, the influence of the joining process on the structure of the involved materials is also shown. Furthermore, the failure behavior under static tensile and shear stress will be shown