Friction properties of clay compounds

Friction is one of the most important factors in energy consumption and in the lifetime of machinery used to prepare and produce heavy-clay products such as brick and roof tiles. Production of traditional heavy-clay products often demands additives to change the properties of the clay processed or those of the products. The effects of different additions of organic and non-organic additives on the friction coefficients of clay compounds were investigated. As opening agents sand and ground brick dust, while as pore forming additives sawdust and ground sunflower seed shell were mixed to the clay in 0, 3 and 5 wt.%. The water content value was set to 20% and 24% of the compounds. Investigation was performed by a special tribometer up to the plastic deformation of a sample. The sand and brick dust lowered the coefficient of friction to different extents. Raising the amount of sand from 3% to 5% caused some 30% decrease in friction while the effect of brick dust was not so significant. Sunflower seed shell lowered friction at 24% moisture content while increasing it at 20% moisture content. Addition of saw dust resulted in higher friction value as compared to pure clay. The results revealed how additives behaved in the clay matrix.