Theory Model And Process Research On Powder Injection Molding Of Ti(C, N) Based Cermets

Ti(C,N)-based cermets used to substitute for cemented carbide is an advanced hard material. Products of Ti(C,N)-based cermets with more complex shape can be obtained by powder injection molding(PIM) than by traditional pressure molding, this expands the range of application of Ti(C,N)-based cermets material. Because the system of ingredients of Ti(C,N)-based cermets is complex and the physical chemical properties of each ingredient is special, there is not an integrated theory model on the powder injection molding. Therefore these types of models are important for theory and practice on improvement of process and computer simulation.This paper develops the study by connecting the achievements of theories on PIM at home and abroad and some results and problems of research on Ti(C,N)-based cermets PIM in our laboratory. The processes of Ti(C,N)-based cermets PIM with modified binder is explored by measuring thermal properties (melting point and weight-loss curve) of each component of the binders, calculating thermodynamics compatibility, testing rheological behavior of modified binder, optimizing the parameters in PIM, completing solvent-thermal two steps debinding experiment, and comparing three types of sintering processes. The best property of sintered patterns in this work is bending strength 805MPa, hardness 84.5 HRA, density 6.62 finally.Based on the results of properties tests on the Ti(C,N)-based cermets PIM in our lab before, body center cubic(BCC) stack structure of powders of Ti(C,N)-based cermets is matched. The best solid loading capacity model is modified by deducing from the pressure-transmission model and binder-coating model. Based on standard model presented by Professor German, connecting the related parameters of rheological behavior of feedstock and structure model of feedstock in the paper, the PIM rheological behavior of feedstock forecasting software, which can fit the values of theories and practice of rheological behavior of feedstock in Ti(C,N)-based cermets PIM, is compiled with VB language. The series of models and software establish some foundations for computer simulation in future.Solvent debinding dissolution constraint model is established and simulated with Fick's second law and macromolecule swelling-dissolving two steps theory model. Furthermore, the reasons of surface cracks from solvent debinding and the extraction process of dissoluble components are explained by the latest model. The typical layer-crack defect of Ti(C,N)-based cermets PIM is explained by establishing a powder-flowing model during thermal debinding process, and the settle method is presented.