Connect, no.131, July/August 2004, p.6
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A multi-faceted protrusion created using Surfi-Sculpt, viewed using a scanning electron microscope |
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TWI has announced the development of Surfi-Sculpt, a revolution in surface treatment, materials processing and joining technology. Surfi-Sculpt uses electron beams to reshape materials precisely and so 'grow' protrusions that risefrom the surface of the material. For each protrusion there can be a corresponding hole into the bulk of the material. The electron beam is controlled by a programmable system comprising hardware and software developed at TWI.
While the physical limits of the process are being explored, protrusions in the order of 2mm high and 200 microns wide have been typical of those created within TWI's laboratories.
As the electron beam is moved across the surface of a material it creates a pool of molten material in a track, or 'swipe'. As the material vaporises, it creates a pocket of pressurised vapour above the swipe at the point of actionof the beam. Surface tension and viscosity of the molten material in the swipe is dependent on its temperature, which varies along the swipe as it cools progressively.
The combined effect of the variance in surface tension along the swipe, and the intensity of the vapour above the swipe, is that material is displaced in the direction opposite to the beam's travel.
Swipes may be repeated or overlapped. With each swipe time more material is displaced from the bulk of the material to a common point. After several passes of the electron beam, a protrusion begins to grow and rises out of the swipepath.
TWI's principal research metallurgist, Bruce Dance, said: 'For the first time we have a tool that enables control and modification of materials properties at many different levels. Mechanical, electrical, magnetic, thermal, andother characteristics can be tailored precisely for specific applications, and this creates a multitude of exciting new possibilities'.
For more information, contact Colin Ribton. E-mail: colin.ribton@twi.co.uk
