Development of leak-tight coupling systems, based on shape memory alloys (SMA, shape memory alloys), working in a wide range of operating pressure from ultra high vacuum (UHV) to high pressure (HP).
SMA couplers offer a unique possibility to generate tight connections and fast clamping/unclamping by changing the temperature of the junction unit, thanks to the extraordinary strain and stress recovery capabilities of the SMAs, related to reversible phase transition mechanisms thermally or mechanically induced.
A significant evolution of the current market solution of SMA-based couplers
Very interesting and novel aspects of this technology, with respect to the state of the art on SMA couplers, with high potential impact on the market.
Main advantages are summarized as follow:
- Development of material processing methods for large diameter coupling (>100 mm). Commercial suppliers provide couplers with diameter ranging from 1 to 100 mm. This is due to the constraints of the current thermo-mechanical processing methods.
- Development of thermo-mechanical processes for fine tuning of the functional response of the SMA coupler, i.e. in terms of shape and force recovery capabilities as well as of the transformation temperatures and thermal stability range. This allow to adapt the coupler to different service conditions. On the contrary commercial solutions provide fixed transformation temperatures.
- Possible remote activation/control by temperature changes thanks to the two-way shape memory recovery capabilities. Thanks to this feature the couplers can be mounted and dismounted by temperature changes. This is a very important advantage with respect to commercial commercial SMA pipe couplers which implement permanent couplings as an alternative to welding technologies.
- Development of design and processing methods to obtain High Pressure (HP) and/or Ultra High Vacuum (UHV) sealing. In particular, UHV sealing properties have been achieved and proved for the first time by ad-hoc developed solutions which involve proper design of the coupling geometry and the use of sealing elements
- Application in critical/harsh conditions, such as exposure to corrosion environments and ionizing radiations. Material damage, at both structural and functional level, Under exposure to ionizing radiations are being analyzed at CERN for the first time by complex experiments involving irradiation facilities. The results of these experiments represent a unique know-how and define new possible application of SMAs in radioactive environments. Corrossion experiments have been planned to be carried out in cooperation with the University partner (University of Calabria).
The proposed technology represents a significant evolution of the current market solution of SMA-based couplers. In fact, thanks to the advantages reported above they actually widen the possible commercial application of such components, especially in critical/harsh conditions where human presence/intervention must be limited. A possible disadvantage can be identified in the more complex thermo-mechanical training processes required to tune the thermal stability range and the two-way shape recovery properties.
In addition, the main disadvantage of the proposed technology with respect to traditional HP or UHV coupling systems (e.g. bolted junctions) is represented by the higher material and processing costs.