Nanoindentation and dilatometric testing of synthetically prepared CaC03

0482465 - ÚTAM 2018 RIV GR eng A - Abstrakt
Ševčík, Radek - Šašek, Petr - Viani, Alberto
Nanoindentation and dilatometric testing of synthetically prepared CaC03.
EUROMAT 2017. European Congress and Exhibition on Advanced Materials and Processes. Abstracts. Volos: Hellenic Metallurgical Society, 2017. ISBN N.
[EUROMAT 2017. 17.09.2017-22.09.2017, Thessaloniki]
Grant CEP: GA ČR(CZ) GA17-05030S; GA MŠMT(CZ) LO1219
Klíčová slova: nanoindetation * CaCO3 * vaterite * aragonite * calcite
Obor OECD: Inorganic and nuclear chemistry

Calcium carbonate (CaC03) is one of the most abundant mineral on the Earth crust which is largely present in limestone rocks, marine reefs and shells. CaC03 can occur in several forms: three anhydrous crystalline polymorphs (calcite, aragonite and vaterite), two hydrated crystal forms (CaC03 .6H20 (ikaite) and CaC03 .H20) and an amorphous phase. CaC03 has importance in the biomineralization processes and it is widespread used in several industrial sectors. All three anhydrous crystalline polymorphs have been detected in several lime-based building materials e.g. in historic mortars [1] or after the consolidation interventions using so-called nanolimes. Nanolimes are suspensions of nanosized Ca(OH)2 particles in alcohols and their carbonation reaction can lead to the formation of the metastable CaC03 polymorphs (vaterite, aragonite) and calcite [2]. Up to date, in the literature, there is lack of the information about the mechanical properties of these phases. In the past, the mechanical tests were performed on samples of the different origins, like biological or natural, and under different measurements conditions not allowing their direct comparison. For the first t ime, t his contribution will present the direct comparison of the hardness, elasticity modulus (Er) and thermal expansions of vaterite, aragonite and calcite. The anhydrous crystalline CaC03 polymorphs were synthetically prepared without the use of additives. [3] The nanoindentation and dilatometric tests have been performed on specimens prepared from powders and measured under the same conditions. Our preliminary results showed that the value of the Er is lowest for aragonite and the highest Er was detected for vaterite.
Trvalý link: http://hdl.handle.net/11104/0277977