A corundum-mullite refractory material

Abstract

A corundum-mullite material has been developed for service at high temperatures under heavy-duty load-carrying conditions and in corrosive media. The material can be used to fabricate a wide range of industrial products: burner stones, stools, stands, supports, protecting sleeves, etc.OTM-959-grade corundum-mullite material for service under conditions of high temperature, mechanical loading, and corrosive medium has been developed. The material is prepared from aqueous suspensions with the addition of a granular filler at the stage of shaping. The major raw precursors are electrofused corundum and fused mullite, which are readily available and not very much expensive materials, both maintaining strength at high temperatures.Using an electrofused corundum in the presence of an electrolyte, a highly concentrated aqueous suspension (a slip) with a density of 2.7 -3.0 g/cm 3 and good binding properties was prepared by wet grinding in a ball mill.Prior to shaping, a granular binder was added to the slip, and the mixture was thoroughly homogenized to a slurry and was cast into plaster molds. The green performs were dried and then sintered at 1450 -1550°C in air. This technology showed very low (if any) sintering shrinkage, which made it possible to fabricate complex-shaped large-sized components with a mass of up to 60 kg. Depending on the component's dimensions and service conditions, the amount of the granular filler and its fractional composition might vary. To enhance thermal stability, 5% graphite could be added to the precursor mixture.Properties of the OTM-959 material are given below:

Effects of pyrolusite additive on the microstructure and mechanical strength of corundum–mullite ceramics

“…The ranges of the lattice parameters are all within 10 À 4 nm magnitude. Additionally, mullite phase symmetry of the corundum-mullite system is not changed, and it still remains in orthorhombic system and Pbam space group [11].…”

Optical Properties of Porous Alumina Assisted Niobia Nanostructured Films–Designing 2-D Photonic Crystals Based on Hexagonally Arranged Nanocolumns

“…Alumina is transparent in the visible spectrum region, thermally stable material, characterized by high hardness and low chemical reactivity [ 1 , 2 , 3 , 4 ]. Alumina is applied in the production of ceramics, sitalls, glasses [ 4 ], refractory materials [ 5 , 6 , 7 ], abrasive materials [ 2 ], adsorbents [ 2 , 4 , 8 ], including chromatography [ 2 , 9 ], catalyst carriers and catalytic active [ 2 , 4 , 10 ], and filter materials [ 6 ]. Niobium entities, including oxides, are distinguished by even higher chemical stability [ 1 ], and are promising for application in heterogeneous catalysis [ 11 , 12 , 13 ].…”