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Bad Lippspringe, Germany

Holscher T.,Calsitherm Silikatbaustoffe GmbH
InterCeram: International Ceramic Review | Year: 2011

The usage of secondary fuels causes unsteady thermal effects in the temperature regime of furnaces, e.g. in the cement industry. Dramatical consequences on the insulation and the metal structure are effected especially by fluorides, chlorides, sulphates and alkali. A German consortium of industrial and academic partners - Calsitherm, Refratechnik Cement, Schöler & Bolte and Lafarge Cement, Institut für Keramik, Glas- und Baustofftechnik (Institute for Ceramic, Glass and Construction Materials) of TU Bergakademie Freiberg, and Fraunhofer Institut für Keramische Technologie und Systeme (Institute for Ceramic Technologies and Systems) - have started a research and development project funded by the German Federal Ministry of Education and Research (BMBF). With the industrial partners the whole process chain from the insulation manufacturer, anchor steel supplier to the furnace lining expert and end user is presented. The project aims to resolve the mentioned engineering and ecological grievances by material and process developments, functionalizing of refractories and corrosion minimization. The main approach is utilization of alkali resistant materials based on "Calutherm" family products, β;-aluminium oxides and alkaline feldspars. This paper presents the first results of the laboratory and field tests.


Schlegel E.,Institute for Ceramic | Holscher T.,Calsitherm Silikatbaustoffe GmbH
InterCeram: International Ceramic Review | Year: 2010

With an increasing usage of secondary fuels more and more problems with corrosion attacks on refractory materials by alkalis, sulphates and especially chlorides and fluorides occur. This paper presents the results of corrosion tests with diatomite bricks, light-weight fire-clay bricks and refractory concretes, calcium silicates and thermal insulation materials based on alumina. Specimens of these materials have been charged with different salt mixtures which have been chosen by their reactiveness and by post mortem analyses of corroded refractories. All inspected materials corrode with even severely destruction of the specimens. Only a new developed material called Beta Calutherm shows no effects on the salt charges and is alkali corrosion resistant.


Schlegel E.,TU Bergakademie Freiberg | Holscher T.,Calsitherm Silikatbaustoffe GmbH | Schneider H.-J.,Calsitherm Silikatbaustoffe GmbH
Keramische Zeitschrift | Year: 2013

The first part features an overview to the properties of all calcium aluminates followed by a presentation of CALUTHERM®, a high temperaturethermal insulating material. CALUTHERM is produced on the bases of SLA-92, a calcium hexaaluminat aggregate, and calcium aluminate cement CA-14 W as binder. The comprehensive studies focus on properties and changes of these raw materials during the technological stages of the CALUTHERM's production. The second part will present CALUTHERM's properties and its variants throughout the production process. A possible correlation between the properties of raw materials and thermal insulation material is researched and finally application examples are presented. CALUTHERM is suited for thermal insulation up to 1600°C and has a remarkable low thermal conductivity near 0.4 W/m⋯K at these high temperatures. For that reason CALUTHERM is a top high-temperature thermal insulating material.


Schlegel E.,TU Bergakademie Freiberg | Holscher T.,Calsitherm Silikatbaustoffe GmbH | Schneider H.-J.,Calsitherm Silikatbaustoffe GmbH
Keramische Zeitschrift | Year: 2013

The first part features an overview to the properties of all calcium aluminates followed by a presentation of CALUTHERM®, a high temperaturethermal insulating material. CALUTHERM is produced on the bases of SLA-92, a calcium hexaaluminat aggregate, and calcium aluminate cement CA-14 W as binder. The comprehensive studies focus on properties and changes of these raw materials during the technological stages of the CALUTHERM's production. The second part presents CALUTHERM's properties and its variants throughout the production process. A possible correlation between the properties of raw materials and thermal insulation material is researched and finally application examples are presented. CALUTHERM is suited for thermal insulation up to 1550 °C and has a remarkable low thermal conductivity. For that reason CALUTHERM is a top high-temperature thermal insulating material.


Huettner W.,Calsitherm Silikatbaustoffe GmbH | Hoelscher T.,Calsitherm Silikatbaustoffe GmbH | Smith R.,Industrial Products International | Quackenbush M.,Prime Material Sales
TMS Annual Meeting | Year: 2011

The combination of Calcium Silicate with carbon fibers is well known and such materials are used for many years in numerous applications, especially as transition plates in billet casters. The carbon fibers used are PAN based (polyacrylonitrile), also the use of pitch based fibers is known. The fibers are chopped; the orientation is mostly parallel to the plane of pressing, but randomly distributed. The weight fraction does in general not exceed 2% [1, 2, 3, 4]. The carbonized fibers oxidize and burn off very fast during the use in liquid aluminium. Therefore after a short time of use at temperatures above 400°C a progressive fade away of the fibers following the heat gradient in the Calcium Silicate is observed. Compared to Calcium Silicate grades without carbon fibers there is obviously no significant difference in the mechanical and physical properties by adding carbon fibers of only around 2%. To combine the mechanical and physical properties of Calcium Silicate and Graphite and to utilize the Graphite properties it is obviously necessary to increase significantly the amount of Graphite and also to select the right type of the carbon material. Of particular interest are to tailor the thermo-physical properties, especially thermal conductivity and coefficient of thermal expansion and to minimize the oxidation of the Graphite component.

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