Question

In vacuum degassing method, low viscosity is considered to have negative influence on the reaction rate.

(a) True

(b) False

The question was posed to me in class test.

Enquiry is from Methods and Materials for Degassing in chapter Foundry Introduction & Materials of Casting-Forming-Welding II

Answer 1

The correct option is (b) False

To explain: The viscosity influences the efficiency of vacuum degassing; a high viscosity is considered to have negative influence on the reaction rate. The viscosity is generally not considered in the kinetics; instead, a constraint is used that limits the viscosity to be below 0.5 Pas. The melt should have low viscosity which also reduces the time involved in the procedure.