THICKNESS DIFFERENCE OF ELECTRODE COATINGS CAUSED BY ELASTIC TURBULENCE OF ELECTRODE COMPOUNDS UNDER CONDITION OF NONISOTHERMAL PRESSURE FLOW

摘要

Generalized and analyzed are the results of investigations carried at the E.O. Paton Electric Welding Institute on technological properties of electrode compounds, promoting thickness difference of electrode coatings. The investigations were carried out using capillary viscosimeter of fixed flow - rheometer with electric drive, which can be used for simulation of the conditions of compound extrusion application over the electrode rods, typical for commercial electric extrusion presses. Thus, specific pressure on compound under condition of stationary flow achieves 60-75 MPa, average gradient of shear rate is gradually regulated in the ranges from 1 to 5 × 10~3 s~(-1), and it makes to 65 × 10~3 s~(-1) for separate types of compound. The compounds for rutile, low-hydrogen and cellulose electrodes, differing by wide range of consistency indices, were investigated. In addition to shear and longitudinal viscosity, the investigations were carried out on a range of change of their modulus of shear elasticity, period of relaxation, criterion of Reynolds elastic turbulence, elastic potential and reversible (elastic) deformation. The results received were analyzed from point of view of existing phenomenological theory of elastic turbulence of polymer materials, combining viscosity and elasticity properties. It is successfully used in the course of many years in rheology of melts and solutions of high-molecular compounds for solving of technological problems of their extrusion processing. Variants of elastic turbulence, detected in capillary and pre-capillary zones, were analyzed. Quality relation of this phenomenon to appearance and nature of coating thickness difference in course of real extrusion application of compound over the electrode rods was shown.