2.3.3 Resistors and Heating

Resistors

	Basic requirements for resistors (still one of the most numerous component in circuits) are:
		Large region of R values (= device resistance in W) within one production technology. Small (ideally vanishing) temperature coefficient . Minimal noise. Small dependence of r on production parameters (good repeatability). No Ageing. Small thermoelectrical coefficients to Cu (you want a resistor, not a thermoelement).
	Materials of choice include
		Ta, Ta based alloys, and in particular "Constantan" (55% Cu, 44% Ni, 1% Mn), a resistor material with an especially small temperature coefficient a_r, but a large thermoelectric coefficient).
		Strange mixtures of conductors and insulators including "Cermet" (short for Ceramics - Metals), e.g. Cr - SiO₂.
	Details and data in the (future) link.

Heating

	Basic requirements for heating elements are:
		High melting point. Chemical stability at high temperatures and in potentially corrosive environments. Mechanical strength at high temperatures.
	The choice of a materials depends significantly on the range of temperatures envisioned. We have:
		FeNiCr, FeNiAl alloys.
		Pt, W, Ta, Mo - stable elements with a high melting point.
		MoSi₂ Among more industrial applications also used as heaters in dish washers - this is very aggressive environment!
		Graphite (up to 3000 K in non-oxidizing gas).
	Some details and data can be found in the links.
		Overview of resistivity and temperature range for some materials
		Maximum temperatures for some materials