Electrospun fibers as drying additive in cement‐bonded alumina castables

Abstract

A simple system to produce titanium dioxide precursor fibers by electrospinning was developed. The phase composition of the fibers was analyzed before and after heat treatment by means of Raman spectroscopy. The effect of these fibers and commercial polypropylene fibers (PP) on low‐cement high‐alumina castables was evaluated. Thermogravimetry was used to investigate the drying behavior of the different batches. In addition, the permeability of sintered cylinders was compared. Elastic moduli and cold modulus of rupture were measured on sintered and on thermally shocked samples to evaluate the thermal shock resistance. As in our previous work, the results showed that the fiber addition was beneficial for the drying behavior. However, the use of electrospun fibers likely caused water retention in the samples during storage. The batch containing PP fibers showed the highest final permeability, confirmed also by mercury intrusion porosimetry and by scanning electron microscopy. Otherwise, the precursor fibers left no pore channel after sintering and the permeability of this batch was the lowest. Thermal shock had no clear impact on bulk density or open porosity for any of the batches. Due to the presence of calcium oxide from the cement binder, hibonite (CaAl12$_{12}$O19$_{19}$) was detected by XRD alongside corundum in all samples.

Improving the green mechanical strength and thermal shock resistance of colloidal silica‐bonded castables using La2O3

“…Corundum refractory castables, owing to their benefits, including good thermal stability, wear resistance, erosion resistance, thermal shock resistance, corrosion resistance, and high strength, are extensively used in circulating fluidized bed boilers, metallurgy, petrochemical, thermal power, and other industries 1–3 . Calcium aluminate cement (CAC) is the most widely used binder in corundum refractory castables 4–7 .…”