Pressure-affected flow properties of powder injection moulding compounds

The effect of pressure and temperature on the flow properties of the materials intended for Powder Injection Moulding (PIM) technology was studied using a single-piston capillary rheometer modified by additional backpressure chamber. The influence of pressure and temperature on shear viscosity has been quantified through pressure and temperature sensitivity coefficients derived from Carreau-Yasuda model. The temperature sensitivity of the 50 vol.% compound based on cemented carbide powder is lower than that of pure polymeric binder, and it varies only slightly with pressure. In contrast, the pressure sensitivity of compounds was found to be higher than that of pure polyolefin binder, and it is decreasing function of temperature. In addition, it is shown that temperature sensitivity of binder, which is considerably enhanced by pressure (in contrast to the PIM demands), cannot be determined as being equal to the properties of particular binder components.