THERMAL TREATMENTS IN GASEOUS NITROGEN: DEWAR N2L
What are CO2 / N2 Dewar?
DEWAR it is a vacuum insulated container, from the word itself, for the containment of liquid nitrogen (like thermos to contain the coffee) this container is filled with liquid nitrogen and the artifact to be treated is immersed inside. Basically, DEWAR is used for shrinking because, with liquid nitrogen which has a temperature of -196 °C, the immersed material contracts allowing you to insert, to fit the motor-shafts on the gear without pressing them. When the shaft-motor returns to temperature, it expands and locks on the gear, welding itself perfectly: this heat treatment is an excellent welding method.