It is like modeling and mimicking of the human body and other living systems which have the ability to self heal.</li></li></ul><li>Microsphere Embedment<br /> A microencapsulated healing agent is embedded in a composite matrix containing a catalyst capable of polymerizing the healing agent.<br />Cracks form in the matrix wherever damage occurs.<br />The crack ruptures the microcapsules, releasing the healing agent into the crack plane through capillary action.<br />The healing agent contacts the catalyst triggering polymerization that bonds the crack faces closed.<br />iv. Also possible at nano scale<br />SEM image of broken microsphere<br />
Materials used <br /> There are several constituent materials which, when combined function as self healing material system:<br />Healing Agent: Dicyclopentadiene (DCPD)<br />Microcapsule shell:Urea–formaldehyde (UF) (mean 166µm diameter)<br />Chemical Catalyst: Bis(tricyclohexylphosphine) bensylidine ruthenium (IV)<br />Flexiblizer: Heloxy 71, Shell Chemical Company used to improve toughness and crack growth stability.<br />Polymer Matrix:Epoxy Polymer Matrix EPON 828<br />Fiber Reinforcement: Carbon Fiber (Plain weave fabric constructed with 3K towns)<br />
Re-healing capable materials<br />Material could use a system of veins to distribute healing agent intelligently<br />The bio-inspired design delivers healing agent to cracks in a polymer coating via a three-dimensional micro-vascular network embedded in the material. Crack damage is thus healed repeatedly. This can also ensure continuous delivery of healing agents for self-repair from a additional reservoir<br />3D Microvascular structure embedment<br />
Electrohydrodynamics<br />NiSO4 can be electrochemically dispersed into the small voids present in the system. <br />Voltage applied across inner and outer surfaces.<br />Damage causes an increase in current density at the location of the damage<br />Increased current density causes particle coagulation at damage site<br />
Shape Memory Alloys<br />Shape memory alloys such as Nitinol (a Nickel-Titanium alloy) exhibit the self healing effect when heated<br />Before heating the material tends to have low yield strength<br />After heating to a certain temperature the material returns to the original state<br />In returning to the original state, large forces can be generated<br />
<ul><li>Anything that cannot be reached for repair at the moment of damage!</li></ul>Civil Structures (Engineered cementitious composite)<br /><ul><li>Tools (Nitinol)</li></ul>Space applications<br />Self healing coatings for steel structure <br />Composite materials for:<br />Aerospace applications<br />High quality sporting equipment<br />Microelectronics<br />Medical uses:<br />To detect a breach in a glove, gown, etc., using electrohydrodynamic technology<br />Potential Applications of Self Healing Materials<br />
Case study<br />Self-healing materials and use thereof for extending the lifespan of a tyre<br />Self-Repairing Aircraft Could Revolutionize Aviation Safety<br />Results & Shortcomings<br /><ul><li>The Maximum strength recoverable til date is about 75-80%
Catalyst, and microsphere ‘clustering’ causes less polymerization
Manufacturing of material is very difficult and expensive
More research is required before real world applications are exercised</li>
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