Extruding Flow Characteristics of Carbon Paste as a Bingham Plastic Body

Abstract

The extruding flow characteristics of carbon paste for electrode have been examined experimentally by the authors of the present paper. The extruding apparatus and nozzles used in the experiment are shown in Fig. 1. The type of the nozzle (the outlet diameter d, the convergent angle A, etc.), the temperature of the paste and the inner wall of the cylinder and nozzle, T_p and T_w, are selected as the experimental variables.
The relation between the piston velocity V and the extruding piston pressure P is represented as the experimental results in Fig. 2-(1)(2)(3). From these results, new experimental equation
(V-V₀)=K(P-P₀) (1)
is derived as the fundamental equation of Bingham plastic body in place of Eq. (2), which has hitherto been used.
It is found that P₀ is affected by none of the nozzle factors and conditions other than the convergent angle of nozzle at nozzle inlet, A. P₀ is named by the authors as “the ultimate limit of the extruding pressure”. The values of P₀ against A are shown in Table I. As regards V₀, the imaginery extruding piston velocity at the ultimate limit pressure, the physical meaning is not clear at this moment, but fairly simple relation is found as is shown in Fig. 3 and Eq. 4. The relationships between fluidity K and other factors (T_p, T_w, d) are found as are shown in Fig. 4.