Simulation of orientation behavior of plate-like particles in powder rolling based on finite element analysis of strain history

Considering the application of powder rolling for efficient production of ceramic plates with grain-oriented microstructure, the effects of the rolling conditions on the particle orientation are examined using numerical simulation. Finite element analysis of the rolling process is performed, followed by the simulation of plate-like particle orientation using the Folgar-Tucker model with the strain history being obtained in the analysis. Because ceramic paste is used as a work piece in the actual rolling process, a friction coefficient between the material and the roll surface is set to a high value, and the progress of the normal and shear strain distributions are computed under some conditions of the reduction in thickness, roll diameter, and the ratio of the rotational speeds of the upper and lower rolls. After calculating the changes in particle-angle distributions, the degree of orientation is evaluated by calculating the average angle of the particles as well as the standard deviation of angle distributions. For equal speed rolling, a greater reduction in the thickness enhances the orientation. When the increase in roll speed ratio is within a certain range, the degree of orientation decreases because of shear deformation in the opposite direction in the lower part of the plate. The orientation, however, can be improved if the increase in differential ratio is large enough.