Nikolay Makarov
D.Mendeleev University of Chemical Technology of Russia, Russia
Title: Ceramics in the system ZrO2-Al2O3 with eutectic additives
Biography
Biography: Nikolay Makarov
Abstract
Statement of the Problem: The ZrO2-Al2O3 system is key for the synthesis of various structural materials; in particular, it is promising for manufacturing of wear-loaded items like friction pairs, cutting tools, etc. One of the most important issues in zirconia ceramics technology is that ZrO2 is subject to intensive recrystallization at temperatures exceeding 1100-1200 °C. This phenomenon leads to a martensitic transformation, accompanied by a significant drop in mechanical strength.
Methodology & Theoretical Orientation: An effective way to prevent recrystallization is to affect the grain of zirconia with an external compressive load, since in the stressed state the tetragonal solid solution does not decompose. It is possible to create an external load by introducing a second phase into the material, the role of which is taken up by alumina. The aim of the work is to create ceramic materials in the ZrO2-Al2O3 system, with predominant zirconium dioxide, having a sintering temperature of 1400-1550 °C, and high mechanical properties. An attempt was made to reduce sintering temperature by the addition of eutectic aids to the batch. The influence of various types of alumina (commercial, obtained by chemical precipitation) on the structural properties, mechanical strength and microstructure parameters was analyzed. Zirconia was obtained by chemical precipitation, partial stabilization was carried out using yttrium chloride. To control the structure and properties of ceramics, modifiers were used in CaO-Al2O3-SiO2 and MnO-TiO2 systems.
Findings: It was found that ceramics with eutectic additives CaO-Al2O3-SiO2 and MnO-TiO2 in the ratio 1: 1 possesses the greatest mechanical strength - 750 ± 35 MPa. Conclusion & Significance: This ceramic material is characterized by the highest mycrohardness of 1200 N/mm2. The material is promising for use as elements of stop valves, mill bodies, cutting tools; wear-resistant structural parts, etc.