Atmosphere monitoring in a continuous sintering belt furnace

The atmosphere composition in a continuous belt furnace during sintering of powder metallurgical aluminium components with ethylenbisstearamide (EBS) pressing agent was determined by Fourier Transform Infrared Spectroscopy (FTIR). The spatial distribution of the decomposition products was measured at four positions in the dewaxing zone. It is shown that the major decomposition products of the dewaxing process are CH groups, which mainly occur between 310 and 410 °C. As the powder compacts pass the dewaxing zone, each part drags along its own bell-shaped gas atmosphere. In the vertical direction, a flow profile with two separated concentration zones is observed, leading to large quantities of unused process gas passing the furnace. The amount of unused gas is mainly controlled by the gas flow and the belt speed of the furnace. In particular, high belt speeds and low gas flow parameters may lead to the introduction of harmful carbon into the sintering zone.