Effect of surface conditions on the workability of clays by forming limit line (FLL) technique

vEFFECT OF SURFACE CONDITIONS ON THE WORKABILITY OFCLAYS BY FORMING LIMIT LINE (FLL) TECHNIQUE(M.Sc.Thesis)Mustafa KILINÇGAZI UNIVERSITYINSTITUTE OF SCIENCE AND TECHNOLOGYDecember 2005ABSTRACTIn this study, three different clay with various mineral contents, taken fromceramic factories shaping ceramic parts by slip casting and die pressing, wereused. The characteristic properties and mineral contents of clays weredetermined by X-ray diffraction analysis, differential thermal analysis, thermalgravimetric analysis, chemical analysis and particular size distribution analysis.The workability is defined as maximum deformation amount x yield strength.In this study, the yield strength was determined from strain-stress graphs using0,2 % Offset rule at a constant strain rate (20mm/min).Maximum deformation amount determined by Forming Limit Line (FLL)method, which is successfully practiced to metals under compression, wasapplied to clays. The clay specimens used to obtain FLL were produced bypressing plastic state clay manually through a cylinder by means of a piston.In this study, length/diameter, (L/D) ratio was kept constant and taken as 1. Atthe constant (L/D) ratio of 1, different friction surfaces were developed usingdiesel oil, nylon and sand paper at the surfaces exposed to compression loadsduring deformation and deformation was continued until the first crack wasviseen. Thus, instead of (L/D) ratio, the effect of different surface conditions onFLL was investigated. The point at which FLL intersects the tensile axis wasobtained as maximum deformation amount.Optimum moisture amount of each clay was determined at different frictionsurface conditions by drawing the graphs as a function of the change ofmaximum deformation amount, yield strength and a combination of both valueswith moisture.Science Code : 710Key Words : Forming Limit Line, Formability, Surface Friction Condition,Maximum Deformation Amount, Clay Workability, Strain,Stress, Yield PointPage Number : 111Adviser : Assoc. Prof. Dr. Süleyman TEKELAssist. Prof. Dr. Bülent BARAN