Thermal sensor
A thermal/overheat sensor for an aircraft includes an outer electrode, an inner electrode, a support layer disposed between the outer electrode and the inner electrode. The support layer contains a state changing material wherein the state changing material is configured to transition between a non-conductive state to a conductive state at a threshold temperature to electrically connect the outer and inner electrodes.
1. A continuous thermal/overheat sensor for an aircraft, comprising:
an outer electrode;
an inner electrode;
a support layer disposed between the outer electrode and the inner electrode; and
a state changing material disposed in contact with the support layer, wherein the state changing material is configured to transition between an electrically non-conductive state to an electrically conductive state at a threshold temperature of an aircraft component or aircraft system to electrically connect the outer and inner electrodes, wherein the support layer is an anodized layer on at least one of an inner surface of the outer electrode or an outer surface of the inner electrode.
2. The thermal sensor of claim 1 , wherein at least one of the outer and inner electrodes are coaxial electrodes.
3. The thermal sensor of claim 1 , wherein the outer and inner electrodes are made of aluminum.
4. The thermal sensor of claim 1 , wherein the support layer can include at least one of a porous ceramic or a porous high temperature polymer.
5. The thermal sensor of claim 4 , wherein the porous ceramic includes glass fiber or the high temperature polymer includes at least one of polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), polyetherimide (PEI), polyphenylsulfone (PPSU), or polysulfone (PSU).
6. The thermal sensor of claim 1 , wherein the state changing material includes a salt mixture.
7. The thermal sensor of claim 6 , wherein the salt mixture includes a chemical ratio of LiNO 3 :NaNO 3 :KNO 3 :NaNO 2 .
8. The thermal sensor of claim 1 , wherein the state changing material is sandwiched between the outer electrode and the inner electrode, and wherein the state changing material is sealed in between the outer electrode and the inner electrode by a sealant.
9. The thermal sensor of claim 8 , wherein the sealant includes a perfluoroelastomer.
10. A method for manufacturing a continuous thermal/overheat sensor, comprising:
anodizing either an outer surface of an inner electrode or an inner surface of an outer electrode to create a support layer thereon;
coating a support layer using a molten state changing material;
coaxially disposing the inner and outer electrodes; and
sealing the support layer and the state change material at an end of the inner and outer electrodes, wherein sealing the support layer includes disposing a sealant on an exposed edge of the support layer.
11. The method of claim 10 , wherein coating includes dip coating the support layer in a molten or aqueous salt mixture or filling a space between the inner and outer electrodes with molten or aqueous salt mixture.