The Paton Welding Journal, 2016, №01



2016 №01 (02)

DOI of Article 10.15407/tpwj2016.01.03

2016 №01 (04)

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The Paton Welding Journal, 2016, #1, 17-29 pages

Rheological investigations of non-isothermal pressure flows of coating mixtures for welding electrodes

A.E. Marchenko

E.O. Paton Electric Welding Institute, NASU 11 Kazimir Malevich Str., 03680, Kiev, Ukraine. E-mail: office@paton.kiev.ua
 
 
Abstract
Continuous flow capillary viscosimeter, presented in the form of abruptly narrowing stepped channel, and INSTRON 1251 testing machine were used to model the processes of pressure flow of coating mixtures for welding electrodes in extrusion chamber and in die space of production extruding machine. Thermocouple measurements were used to study the thermal conditions in pre-capillary zone, and visualization method was applied to analyze the structure of flow in it. Mathematical apparatus developed for calculation of rheological characteristics of polymer materials in the state of viscoelastic pressure flow was applied to calculate similar characteristics of the two types of coating mixtures for two types of low-hydrogen electrodes made with application of viscous in one and low-viscous liquid glass in another one. Grain composition of their filler is the same. Values of viscoelastic characteristics of the mixtures were calculated, including shear and longitudinal viscosity, elastic potential, first difference and coefficient of first difference of normal stresses and the relaxation period. Their dependencies on geometrical dimensions of stepped channels and values of volume flow of the mixture at capillary measurements were analyzed and commented upon, allowing for suspension nature of the mixtures, as well as resistance of pressure flows formed in them to viscoelastic instability. 12 Ref., 3 Tables, 12 Figures.
 
Keywords: rheology, welding electrodes, mixtures for coatings of low-hydrogen electrodes, viscoelastic characteristics of mixtures, pressure flow instabilities
 
 
Received:                30.11.15
Published:               15.03.16
 
 
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