Studies on Cavitation Damages

Abstract

Tests in a new chamber for flow cavitation led to damages which are characteristic of erosive destruction caused by imploding cavitation bubbles. To develop material of greater cavitation resistance, it is necessary to find out exactly the different stages of damage. To do this, we started to examine model materials in a special testing chamber. In the case of soft aluminum, these damages, caused by single imploding bubbles, give an idea about the way of load that is the effect due to micro-liquid-jets which impact the specimen surface under special conditions. Typical stages of deformations, formation of cracks and fractures are described with regard to the structures of the model materials by scanning electron microscope. To transfer the different stages of damages from one material to others of the same crystalline structure, changes at different stages caused by the different mechanical properties, for example, as in the case of copper, must be taken into consideration.

Thermal Diffusion Factor and Quantum Collision Integrals for the H2–4He System: The Effect of Inelastic Collisions

“…The adsorption and retention of hydrogen by nickel is very good whereas for copper, while not as good as nickel, it is significant, 19 Since the sorption times are on the order of several hours to several days depending upon the conditions,20 one is led to speculate that in the present experiments with the nickel trennschaukel, the adsorption had equilibrated well before the experiments were complete. The average amount of hydrogen left in the original sample after the duration of the experiment dropped by 4% at 450 0 K and by 45% at 550 o K. At 650 0 K only a trace of it could be found at the end of the experiment, and hence no value of aT was obtainable.…”

Ultrasonic Welding of Aluminum Alloys to Fiber Reinforced Polymers

“…Thereby it was found out that a joint can also be realized without the weld current only by ultrasonic oscillation . In the industrial production the ultrasonic metal welding process was established in the 1950s . At the same time also many application fields for ultrasonic plastic welding have been opened up, a welding variant which is characterized by an oscillation amplitude perpendicular to the welding zone .…”

Considerations of Microstructural Influences for Diffusion Welding of Metals in Microsystem Technology

“…in a significant surface deformation (and hence improved dislocation density). [30,33,34] It can be concluded, that this procedure is not reproducible. Fragments of the passivation layer were smeared into the surface and that the degree of cold working was altered at least at the surface level.…”