Methods for the Elimination of Weighing Troubles Due to Convection in a Microbalance

The paper deals with an investigation into the fluctuations encountered in thermogravimetric measurements using a microbalance with suspended pans, in a temperature range up to 1200 C. The convection resulting at gas pressures above 200 torr, which is responsible for these fluctuations, depends on the pressure, the type of gas used, the temperature gradient, and the geometry of the arrangement. The difficulties have been overcome by using long, thin suspension wires; shielding samples and balance beam with horizontally suspended foils attached to the suspension wire or to the balance tube; using heaters with a homogeneous temperature zone and a helium gas stream protecting the measuring system.