Physico-Chemical nanomaterials science

Effect of Intensifying Additives on the Properties of Celsian Ceramics
Lisachuk G.V.1, Kryvobok R.V.1, Voloshchuk V.V.1
1 National Technical University "Kharkiv Polytechnic Institute".
Kyrpychova str., 2, Kharkiv-61002, Ukraine.
E-mail: valenty93vol@gmail.com

The creation of radio-transparent ceramic materials with a set of high performance characteristics is currently an urgent need for modern aviation and rocket and space industries. Modern technologies make it possible to obtain materials with different properties by modifying them with different additives.
In this work, the effect of intensifying additives on the properties of Celsian ceramics is studied. The oxides SnO2, Li2O and Cr2O3 and the eutectic additive SnO2 – Li2O were used as intensifiers. Additives were added to the mixture in the amount of 0.5 - 2 wt.% over 100 wt.%. Firing was carried out at temperatures of 1,200°C, 1,250°C and 1,300°C C with holding at the maximum temperature for 1 hour. The assessment of the effect of additives on the sintering of the Celsian phase was studied by comparing the physical and dielectric properties of the test samples. Structural-phase features of the samples were studied by X-ray phase analysis and scanning electron microscopy.
The results of studying the microstructure of test samples obtained at a temperature of 1,200°C, containing the eutectic additive Li2O – SnO2 (1 wt.%), indicate the presence of monoclinic Celsian crystals evenly distributed in the glass phase and single closed pores up to 40 μm in size, the presence of which is explained by the accelerated mode firing with a short interval of isothermal exposure. A positive effect of the addition of SnO2 – Li2O on the low-temperature activation of the process of synthesizing the Celsian phase and obtaining a densely sintered ceramic material has been established.
It has been established that, in terms of its dielectric properties, the obtained ceramic material belongs to radio-transparent materials. Celsian ceramics synthesized at a low temperature of 1,200° C with an exposure of 1 hour and with the addition of 1 wt. % SnO2 – Li2O, is characterized by the following properties: water absorption –  7.1%, apparent density – 2.6 g/сm3, dielectric permittivity – 8.7, dielectric loss tangent – 0.09.