Effects of binder and thermal debinding parameters on residual carbon in injection moulding of Nd(Fe,Co)B powder

Abstract

Thermal debinding properties of several organic binders for the injection moulding of Nd(Fe,Co)B powder have been investigated. The investigation included analysis of the residual carbon content, which affects the magnetic properties of the sintered magnet. The effect of several debinding parameters such as specimen thickness, debinding atmosphere, gas flowrate, heating rate, and debinding temperature were also studied. Depending on the pyrolysis mechanism, binders gave specific results for the residual carbon. The molecular weight was found to have a large effect on the residual carbon and showed a logarithmic linear increase with increase in residual carbon. Hydrogen gas was found to be the most appropriate atmosphere for the debinding of the moulded specimens. Slow heating and high temperature were found to be effective for low residual carbon. Gas flowrate showed little effect and specimen thickness showed no effect, except with stearic acid.