Properties of refractories from ZrO2 stabilized by the method of plasmachemical treatment

Results of an experimental study of the sinterability and resistance of zirconia-base materials stabilized by the method of plasmachemical synthesis to the action of the main components of metallurgical slags are presented. It is shown that the materials possess the highest resistance to the action of Fe₂O₃, Al₂O₃, and basic slag of the SiO₂−CaO−Fe₂O₃ system, are less resistant to the action of acid slag of this system, and decompose actively under the effect of SiO₂. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 2, pp. 13–15, February, 1998.     

Production process and the properties of lightweight articles made from ZrO2

Conclusions The rheological and technological properties of mineralized foams based on ZrO₂ suspensions stabilized with Y₂O₃ and foams with gummy resin emulsions have been studied.It is shown that the concentration, the grain composition of the suspension, the foam/solid ratio, and the addition of gypsum have a significant effect on the properties of the foam masses and end products.Lightweight foam blocks of significant size have been obtained; these have excellent user properties.Translated from Ogneupory, No. 8, pp. 40–44, August, 1981.     

The long-term high-temperature behavior of refractories produced from ZrO2 stabilized with Nd2O3

Conclusions A technology was developed for the production of zirconia refractories from ZrO₂ stabilized with Nd₂O₃. The thermal strength of the product is adequate for long-term service at a large (200–300°C/mm) temperature gradient. Products based on a zirconia — neodymium solid solution can be used several times.It was established that no appreciable Nd₂O₃ vaporization and, consequently, no appreciable destabilization of the ZrO₂ develops in a neutral medium at 2100–2500°C.The solid-phase processes developing at 2100–2500°C in products from a mixture of 70% cubic solid solution (88 mole % ZrO₂+12 mole % Nd₂O₃) and 30% unstabilized ZrO₂ fired at 1750°C consist of the redistribution of the Nd₂O₃ between the cubic solid solution Nd₂Zr₂O₇-ZrO₂ and the unstabilized ZrO₂, and the diffusion of some of the Nd₂O₃ from the cooler to the working zone.Translated from Ogneupory, No. 3, pp. 52–55, March, 1976.     

CaO稳定ZrO2耐火材料的相组成和热膨胀

对CaO稳定ZrO2耐火材料的相组成和热膨胀行为进行了研究.重点讨论了三种具有不同相组成的CaO稳定ZrO2材料的热膨胀特性.研究结果表明,通过调整ZrO2的稳定程度,可以优化材料的相组成和热膨胀行为,从而改善材料的抗热震性能,并有望使耐火材料的综合性能得到提高.     

Effect of the pressure of cold isostatic pressing and the sintering temperature on the properties of ceramics made of partially stabilized ZrO2

The physicomechanical properties of a ceramics composed of ZrO₂+3 mol.% Y₂O₃ and fabricated by cold isostatic pressing (CIP) at up to 0.8 GPa with sintering at 1440–1620°C are described. It is shown that the material with a low content of admixtures sinters only at 1620°C at a pressure of 0.6–0.8 GPa and possesses a density of 6.0 g/cm³, an ultimate bending strength of 900 MPa, and a fracture toughness of 8 MPa·m^1/2. For the material with a high content of admixtures sintered at 1550°C and pressed at a pressure of 0.6 GPa the same parameters are 5.95 g/cm³, 700 MPa, and 12 MPa·m^1/2. It is established that CIP promotes sintering of Y-PSZ ceramics. CIP has the best effect on the mechanical properties of high-purity materials. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 8, pp. 17–21, August, 1997.     

High-strength ceramic materials based on polycrystalline tetragonal ZrO2 stabilized by Lu2O3

The effect of Lu₂O₃ on low-temperature stabilization of the tetragonal modification of ZrO₂ is considered. The subject of study is ZrO₂ - Lu₂O₃ binary systems with 1 –9 mole % Lu₂O₃ for specimens of ZrO₂ powders prepared by the method invented by the authors. It is established that low-temperature stabilization oft- ZrO₂ occurs in the region of 6 –8 mole % concentration of Lu₂O₃. The obtained ceramic material has a density of 99.8% of the theoretical value, an ultimate bending strength of at least 800 MPa, and a crack resistance of at least 13 MPa · m^1/2 at a content of Lu₂O₃ equal to 6 –8 mole %     

Phase transformations in stabilized ZrO2-Al2O3 compositions and properties of zirconium-corundum refractories

Solid-phase reactions in mixtures of cubic ZrO₂ with different compositions synthesized by induction melting and Al₂O₃ with different thermal prehistories are investigated at a temperature of 1750°C. Data on the change in the principal engineering properties of zirconium-corundum refractories as a function of their chemical composition are obtained.Translated from Ogneupory, No. 12, pp. 5–8, December, 1995.     

Vibrocast large and intricate products made from fused mullite

Conclusions The production technology of large and intricate mullite and mullite-corundum products was developed using the vibrocasting method (based on fused mullite).It was shown that the products obtained by vibrocasting possess significantly superior and more uniform properties throughout the volume (body) than the products manufactured by air ramming.Translated from Ogneupory, No. 2, pp. 5–7, February, 1988.     

Enhanced ionic conductivity and thermal shock resistance of MgO stabilized ZrO2 doped with Y2O3

The present work focused on the effect of Y₂O₃ co-doping on the phase composition, microstructure, ionic conductivity and thermal shock resistance of 8 mol% MgO stabilized ZrO₂ (Mg-PSZ) electrolyte ceramics for high temperature applications. The addition of Y₂O₃ could promote the process of monoclinic-to-cubic/tetragonal phase transformation and became the metastable phase at room temperature. Meanwhile, the grain size of Mg-PSZ decreased. It was demonstrated that an appreciable increase in the ionic conductivity and compressive strength occurred on substituting MgO with Y₂O₃ in the Mg-PSZ electrolyte ceramics across the measured temperature range. Moreover, the Y₂O₃ addition could restrain the adverse effect of the cyclic thermal shock on the ionic conductivity and compressive strength of Mg-PSZ. The main reason was that the increase of the amount of monoclinic phase caused by cubic/tetragonal-to-monoclinic phase transformation by the cyclic thermal shock was restrained after the Y₂O₃ addition.     

Glass fiber for reinforcing building products made from Portland cement

Translated from Steklo i Keramika, No. 6, pp. 30–32, June, 1989.     

Effects of TiO2 doping on the defect chemistry and thermo-physical properties of Yb2O3 stabilized ZrO2

Yb₂O₃ stabilized ZrO₂ (YbSZ) doped with different TiO₂ contents were produced, and their phase structure, thermal conductivities and thermal expansion coefficients were investigated. A new solid-solution model is proposed, i.e. Ti⁴⁺ would take the interstitial sites when its content is below a critical value (≤2.5 mol%) and then substitute for Zr⁴⁺. The abnormal lattice volume and thermo-physical properties of 2.5 mol% TiO₂ doped YbSZ, and the positive effects of TiO₂ doping on the thermal conductivity at moderate doping level are consistent with the new defect model. However, monoclinic phase is formed when the TiO₂ content reaches to 10 mol% and its content increases with doping content, which have negative influence on the thermo-physical properties. Considering the comprehensive properties, 10 mol% TiO₂ doped YbSZ is considered as a promising thermal barrier coating ceramic.     

Mechanically robust ZrO2 foams with 3D reticular architecture prepared from chemical-modified ZrO2 powder

Engineering mechanically robust ZrO₂ foams with three-dimensional (3D) reticular architecture and high porosity is extremely challenging. In current work, we presented an approach for constructing such cellular ceramics via a combined polyurethane foaming and chemical grafting method. Ester functional groups were chemically grafted on the ZrO₂ powder surface to enhance its dispersibility. This approach caused the micron-sized windows to assemble onto the cell wall of porous framework, contributing to 3D interconnected reticular architecture. The resulting products with such cellular architecture possessed a high porosity level of 89.2% and maintained an ultrahigh compressive strength of 8.5 MPa. Our results open up new opportunities for fabricating high-performance ZrO₂ foams toward practical applications.     

ZrO2粉体及陶瓷的制备

叙述了ZrO2的基本性能和应用，介绍了ZrO2微粉和超细粉的制备方法及目前ZrO2结构陶瓷生产常用的成型方法，比较了几种成型方法的优缺点，指出了成型和烧成是较关键的两道工序。同时详细分析了干压成型中分层和烧成过程中开裂出现的原因，并提出了解决的办法。     

Quartz products made by slip casting

Conclusions From finely milled fused quartz it is possible to obtain, by the slip method, adequately strong quartz products with high thermal-shock resistance at low firing temperatures. A substantial increase in the strength of the quartz products can be obtained by impregnating them with silicone resins followed by firing at 1100°C.Translated from Ogneupory, No.1, pp.47–49, January, 1967.