In the course of thermal decomposition of the magnesium sulphate hydrates MgSO4.nH20 (n = 7; 6; 5; 4; 3; 2; 5/4; 1) the intermediate steps MgSO4.3H20, MgSO4.2H20, MgSO4.H20 and fl -MgSO4 are observed under quasi-isothermal and quasi-isobaric conditions at p ~ 0.1 MPa dependent on the water contents. The structure of the obtained monohydrate phase is identical with that of kieserite. Thermal decomposition of the magnesium sulphate hydrates is essentially influenced by the water vapour partial pressure.The system MgSO4.H20 is characterized by the occurrence of a great number of hydrates; however, above 25 ~ only MgSO4.7H20 (epsomite), MgSO4.6H20 (hexahydrite) and MgSO4.H20 (kieserite) are contained in the form of stable solid phases in aqueous solution [

This paper presents a comparative study of the effects of calcium hydroxide based agents on consolidating a lean lime mortar. In the first part, it describes the properties and characteristics of CaLoSiL® – a new stone strengthener based on colloidal suspensions of lime nanoparticles in various solvents. It further summarizes the results of recent tests on the influence of applying nano-agents based on colloidal calcium hydroxide dispersed in ethanol or isopropyl alcohol (CaLoSiL®), and compares them with the effects of lime water and with a traditional barium hydroxide treatment. The tests were carried out on non-standard test specimens fabricated from a lean mortar (1:9) and developed specially for the purpose of testing the relatively low strengthening effects that are typical for lime water consolidation. The comparison presented in this paper is based on the mechanical characteristics of consolidated lime mortar.

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Investigations were conducted to test the use of amorphous silicon nitride as a basic catalyst. Silicon nitride powders characterized by a high specific surface area were prepared by gas‐phase ammonolysis of tetrachlorosilane. The Knoevenagel condensation of benzaldehyde and malonitrile served as a test reaction to characterize the catalytic properties of the materials. It was found that favorable synthesis conditions result in powders showing a stronger catalytic activity than high surface magnesium oxide. However, a disadvantage is the sensitivity of the amorphous silicon nitride against water.

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