Papers by Keyword: Carbonyl Iron Powder

Abstract: Rheology of polymer-metal powder mixture containing a significant amount of metal powder loading determines its flowability through an extrusion die. To make sheets from such mixtures, geometries based on Coat-hanger, Fishtail and ‘T’ type designs are often used. Flow properties such as flow rate, viscosity, residence time, instantaneous velocity and pressure distribution in different type of dies have been used in simulations in Ansys (CFX or fluent). The present paper describes the special design of the fishtail type die geometry with adjustable part at lip land to make sheets from a polymer-metal powder mixture by extrusion. This also includes the design of primary manifold, tapered pre-land, secondary manifold and lip land geometries to obtain uniform velocity at the exit of the die and as uniform a pressure distribution as possible. It includes designing of suitable die profiles in each of these four zones based on the experimentally established constitutive equations using a Melt Flow Index tester.

Abstract: In present research work, metal injection molded cylindrical samples containing the mixture of carbonyl iron powder and high-density polyethylene (HDPE) were compressed at various strain rates. Three mixtures of carbonyl iron powder and HDPE were prepared to contain 80 %( Material A), 86 %( Material B) and 92 %( Material C) metal powder by weight. Compression tests were performed on the cylindrical samples at different crosshead velocities of Universal Testing Machine varying from 0.6-25 mm/min. True stress-true strain behavior of these samples under uniaxial compression test was studied. Based on these curves, polynomial equations were formulated to describe the plastic deformation behavior of the various mixtures at various cross head velocities. The Material C samples showed higher strength as compared to samples from the other two materials. However, Material A showed superior deformation behavior.

Abstract: In this paper, experimental study of the microwave reflection behavior in MRF was carried out. The results showed that at the same frequency the microwave reflectivity of MRF decreased with the increasing of magnetic field strength; and with the increasing of particle concentration, microwave reflectivity decreased, monotonously. Under the given magnetic field, with the increasing of microwave frequency, it first decreased, there is a lowest point at 9.2GHz, and then it increased. Usually, it is considered that the change of internal structure of MRF under external magnetic field is the main reason for the regulation behavior of microwave reflectivity.

Abstract: In this paper, one thin microwave absorbing sheet employing carbonyl-iron powder (CIP) and chlorinated polyethylene (CPE) was prepared. The pattern and static magnetic properties of CIP were characterized by scanning electron microscope (SEM) and vibrating sample magnetometer (VSM), respectively. The electromagnetic parameters and loss mechanisms of CIP were measured and discussed. The microwave absorption properties of composite sheets with different thicknesses and CIP ratios in matrix were investigated by measuring reflection loss (RL) in 2-18GHz. The results showed that the microwave absorption properties could be optimized by controlling CIP content and thickness of sheet. For the sample with the weight ratio (CIP:CPE) of 10:1 and 1mm thickness, the absorption bandwidth (RL below -4dB) achieved 14GHz (4-18GHz).