Physico-Chemical nanomaterials science

Radio-transparent ceramic materials based on celsian -slavsonite ceramics
V.V. Voloshchuk1, G.V. Lisachuk1, R.V. Kryvobok1, A.V. Zakharov1, Yе.V. Chefranov1

1 National Technical University "Kharkiv Polytechnic Institute". 
Kyrpychova str., 2, Kharkiv-61002, Ukraine. 
E-mail: valenty93vol@gmail.com

The system SrO – BaO – Al2O3 – SiO2 attracts the attention of researchers in terms of the possibility of synthesis of heat-resistant and radio-transparent materials, which simultaneously contain the phases of slavsonite (SrO·Al2O3·SiO2) and celsian (BaO·Al2O3·SiO2). 
Previously, we carried out tetraedration of the SrO – BaO – Al2O3 – SiO2 system and experimentally selected a figurative point that corresponds to the stoichiometric composition of compounds of celsian and slavsonite, having the following chemical composition by weight, wt.%: BaO – 10,2-11,7; SrO – 30,0-31,5; Al2O3 – 26,8; SiO2 – 31,5.
In this work, we studied the firing temperature of 1150, 1200, 1250 °C for the following ceramic properties: dielectric constant, water absorption, open porosity, apparent density and flexural strength.
For formation of products from radio engineering ceramics of complex configuration the method of casting from suspensions in gypsum is used. The prototypes were made by the following technology: the first stage – synthesis at a temperature of 1200 °C with hour endurance; grinding of synthesis products in a planetary mill to a residue on a sieve 0063 not more than 0.2%; preparation of slip with the addition of 0.1 wt.% diluent additive Dolapix PС 67 and humidity - 30%. The second stage - casting a slip with a temperature of 35 °C in plaster molds; drying of billets, firing of products at temperatures of 1150, 1200 and 1250 °C with 2 hours exposure and further machining.
Based on the analysis, it was found that the samples fired at a temperature of 1250 °C are characterized by the best properties: dielectric constant, ε = 9.4, water absorption – 5.6%, open porosity – 13.7%, apparent density – 2.4 g/cm3, flexural strength – 21.2 MPa. Further research is aimed at studying the dielectric and physicо-mechanical properties in a higher temperature range.