Development of Actuators for Repairing Cracks by Coating W Wires with Reactive Multilayers

Area of Science:

• Materials Science
• Nanotechnology
• Surface Engineering

Background:

• Metallic materials are susceptible to crack propagation, compromising structural integrity.
• Developing methods for in-situ crack repair is crucial for enhancing material durability.
• Reactive multilayer thin films offer potential for localized heat generation.

Purpose of the Study:

• To optimize the coating of tungsten wires with reactive multilayer thin films.
• To induce an exothermic self-propagating reaction for crack filling applications.
• To investigate the potential of these coatings as self-healing actuators.

Main Methods:

• Deposition of Nickel/Me (Me = Aluminum, Titanium) multilayers onto tungsten wires using DC magnetron sputtering.
• Characterization of film cross-sections using electron microscopy before and after electrical ignition.
• Development of a novel substrate holder to improve film quality.

Main Results:

• Optimized Ni/Al and Ni/Ti multilayer films on tungsten wires (0.05 and 0.20 mm diameter).
• A self-propagating reaction was successfully initiated in Ni/Al films via electrical current, producing B2-AlNi intermetallic phase.
• Ni/Ti films exhibited non-self-propagating reactions, while Ni/Al films showed improved quality with a new substrate holder.

Conclusions:

• Tungsten wires coated with reactive Ni/Al multilayers can generate localized heat through a self-propagating reaction.
• This process shows promise for liquifying low melting point materials to fill cracks.
• The developed system holds potential for creating self-healing actuators in metallic materials.