Name the component that has positive temperature coeficient of resistance.

Commonly used PTC materials include:

• High density polyethylene filled with a carefully controlled amount of graphite, so that the volume increase at the glass transition temperature causes the conducting particles to break contact (also known as Polyswitch fuses)
• Titanate ceramic materials, which work by grain boundary effects

PTC materials are sometimes used to make heating elements, as such elements act as their own thermostats, switching off the current when reaching their maximum temperature.

You can read more details at the url above.