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Saint Petersburg, Russia

Pivinskii Y.E.,OOO NVF Kerambet Ogneupor
Refractories and Industrial Ceramics

Comparative evaluation is given for production and application of contemporary quartz steel-pouring ladle refractories for OAO Dinur CBCM production with similar corundum-graphite refractories produced in the Russian Federation by overseas technology using imported equipment. In spite of numerous predictions the actual 45-year practice of continuous improvement of quartz refractories demonstrates their good viability. Good technical and economic efficiency of their production and application is achieved by implementation of HCBS- and ceramic concrete technology with application of unique centrifugal molding used for the first time on an extensive industrial scale. © 2015 Springer Science+Business Media New York Source

Chronology is considered for development of research and introductory work in the field of centrifugal casting, implemented in the production of quartz steel-pouring refractories. Large scale application of centrifugal casting is used for the first time in domestic and overseas practice for ceramic and refractory production. The main requirements are considered for original casting systems and regimes making it possible to obtain high density semifinished product. Prospects are shown in a number of examples of using the method in casting objects based on HCBS of other materials. © 2015 Springer Science+Business Media New York Source

Examples are provided of the efficiency of adding refractory clays in HCBS technology and ceramic concretes. Properties of castings prepared by slip casting based on HCBS of composite composition in bauxite – very fine quartz glass (VFQG), and additions of refractory clay (1 – 10%) are studied. The effect of continuous nonisothermal heating up to 1500°C on specimen linear dimensions is studied by means of a high-temperature dilatometer. Data obtained are compared with specimen apparent porosity after isothermal firing with soaking for 1 h in the range 800 – 1500°C. Maximum linear shrinkage with nonisothermal heating and minimum value of apparent porosity after isothermal firing correspond to the range 1200 – 1500°C. Maximum indices are noted at 1500°C for both specimen growth and also porosity due to occurrence of secondary mullitization. © 2016 Springer Science+Business Media New York Source

Pivinskii Y.E.,OOO NVF Kerambet Ogneupor | Dyakin P.V.,Saint Petersburg State University
Refractories and Industrial Ceramics

The effect of nonisothermal heating temperature in the range 1100 – 1500°C on shrinkage indices and and degree of cristobalitization is studied for quartz steel-pouring refractory specimens with a ceramic concrete structure. Cristobalite formed at elevated temperature has a reduced (150 – 220°C) transition temperature into the low-temperature form. Quartz steel-pouring refractories with a ceramic concrete structure have good thermal shock resistance, and in contrast to corundum-graphite refractories, requiring preliminary high-temperature heating, may operate without the latter (“cold start”). © 2016 Springer Science+Business Media New York Source

The initial stages of sintering and mullite formation are studied for specimens based on HCBS of complex composition prepared by combined wet milling of high-alumina bauxite and fuzed quartz. The starting materials have a different ratio of components and solid phase particle fineness. The initial sintering stage is in the range 900 – 950°C, and mullite formation 1100 – 1150°C. In the range 1150 – 1200°C there are simultaneously both sintering and mullite formation. Depending on fineness and fuzed quartz HCBS content the maximum amount of shrinkage is 0.35 – 0.60%. An increase in firing temperature to above 1200°C is accompanied by specimen growth and an increase in porosity. Even with an insignificant level of the proportion of sintering pores (0.09 – 0.11) materials have an ultimate strength in bending of 100 – 130 MPa and open porosity of 14 – 16%. © 2016 Springer Science+Business Media New York Source

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