Using continuous wafer-curvature measurements, stress generation was monitored as nickel thin films reacted with silicon substrates to form Ni 2 Si during isothermal anneals. A large compressive force developed during the reaction, but gradually relaxed after the reaction was complete. From a model for reactive film formation, a lower limit for the instantaneous stress associated with compound formation was found to be −2.00 ± 0.75 GPa. This instantaneous stress can be explained by a volumetric strain of 1.65 ± 0.62%, which is much smaller than the theoretical volume expansion of 62% in this system. These results suggest that significant inelastic deformation occurs during silicide formation. It was also found that diffusive creep relaxes the growth stress after the reaction. The observed instantaneous stress indicates that the energy of deformation associated with the reaction is of the same order as the energy that drives it, suggesting that stress generation and stress relaxation can play a significant role in the kinetics of reactive film formation.
Scientific injection molding technologies involve the integration and collaboration of cyber-physical systems and smart manufacturing. In order to achieve adaptive process control and production optimization, injection molding systems with real-time sensing have gradually become the development- and application-trend of smart injection molding. At the same time, this technology is a highly non-linear process in which many factors affect the product quality during long-run fabrication processes. Therefore, in order to grasp changes in the characteristics of plastic materials and product quality monitoring, the injection process has become an important research topic. We installed sensors in the molding machine (injection barrel, nozzle, and mold-cavity) to collect the melting pressure and used different materials (semi-crystalline and amorphous polymer; the melting-fill-index (MFI) is unified to 14.5 ± 0.5 g/10 min) to explore the influences of melting pressure variation and its viscosity index on the quality characteristics of molded products. The experiment reveals that a combination of barrel, nozzle, and mold-cavity sensing on the melt-pressure trend-based injection process-control incorporated with viscosity index monitoring can confirm the weight and shrinkage variation of the injection product. At the same time, the pressure and viscosity index value measured and calculated during the melt-filling of two materials with similar MI resulted in significant variations in the amorphous polymer. This study showed the possibility of mastering and controlling the rheology (barrel position) and shrinkage properties of polymers and successful application in various product-quality monitoring platforms.
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