A novel binder system for hardmetal powder extrusion moulding (PEM) process has been developed. The binder system comprises a major fraction of a mixture of low molecular weight components (LMWCs) and a minor fraction...A novel binder system for hardmetal powder extrusion moulding (PEM) process has been developed. The binder system comprises a major fraction of a mixture of low molecular weight components (LMWCs) and a minor fraction of very finely dispersed polymer. The feedstocks are mixed as a thick slurry at a suitable temperature and are rapidly homogenized by stirring at an adequate shear force. The binders are removed by thermal debinding. The thermal debinding mechanism has been investigated by thermogravimetry (TG) and differential thermogravimetry (DTG). At the first stage of debinding, the LMWCs are removed. These open up pore channels which allows much faster removal of the remaining polymer component during the subsequent stage. The microstructures of the moulded green parts were observed by scanning electron microscopy (SEM). The debound samples were sintered at different temperatures, and the sintered samples properties were measured.展开更多
The thermal debinding dynamics of newly developed binders for cemented carbides extrusion molding was studied. It is shown that the thermal debinding processes can be divided into two stages: low temperature region, i...The thermal debinding dynamics of newly developed binders for cemented carbides extrusion molding was studied. It is shown that the thermal debinding processes can be divided into two stages: low temperature region, in which the low molecular mass components (LMMCs) are removed; and high temperature region, in which the polymer components are removed. The rate of thermal debinding is controlled by diffusion mechanism. The thermal debinding activation energies were solved out by differential method and integral method. The results show that the addition of other components acted as a catalyzer can effectively decrease the activation energy of thermal debinding processes.展开更多
基金This research was supported by the National Natural Science Foundation of China (grant No.5964120, No.69971007). The financial support is gratefully acknowledged.
文摘A novel binder system for hardmetal powder extrusion moulding (PEM) process has been developed. The binder system comprises a major fraction of a mixture of low molecular weight components (LMWCs) and a minor fraction of very finely dispersed polymer. The feedstocks are mixed as a thick slurry at a suitable temperature and are rapidly homogenized by stirring at an adequate shear force. The binders are removed by thermal debinding. The thermal debinding mechanism has been investigated by thermogravimetry (TG) and differential thermogravimetry (DTG). At the first stage of debinding, the LMWCs are removed. These open up pore channels which allows much faster removal of the remaining polymer component during the subsequent stage. The microstructures of the moulded green parts were observed by scanning electron microscopy (SEM). The debound samples were sintered at different temperatures, and the sintered samples properties were measured.
文摘The thermal debinding dynamics of newly developed binders for cemented carbides extrusion molding was studied. It is shown that the thermal debinding processes can be divided into two stages: low temperature region, in which the low molecular mass components (LMMCs) are removed; and high temperature region, in which the polymer components are removed. The rate of thermal debinding is controlled by diffusion mechanism. The thermal debinding activation energies were solved out by differential method and integral method. The results show that the addition of other components acted as a catalyzer can effectively decrease the activation energy of thermal debinding processes.
