Chemometric Comparison of Data Files Using Several Thermal Analytical Techniques for Dating Fossil Bones from Two Old Burial Sites.

Background:: The possibility of estimating the age of fossil bones using only classic thermogravimetry, on the basis of proper % mass loss ratio values, has been widely considered in the past years. Objective:: Our research has brought some innovations to the previous background, by using chemometric methods and by processing the numerical files of whole thermogravimetric curves. The objective of this paper is the selection, among the main thermal analysis methods available, i.e. thermogravimetry (TG), derivative thermogravimetry (DTG), differential thermal analysis (DTA) and thermal dilatometry analysis (TDA), of the most suitable one, in order to evaluate the age of fossil bones. Methods:: Fossil bone samples from two ancient cemeteries in Sudan were analyzed using different thermal methods (TG, DTG, DTA and TDA). Data of whole recorded thermal curves have been processed by PCA analysis. Results:: A systematic comparison of several thermal analytical techniques allowed to conclude that TG or DTG curves can provide more appropriate information to determine how old fossil bones of different ages are, as evidenced by PCA processing of the entire file set of TG or DTG curves. Conclusion:: It can be concluded that the chemometric processing of TG or DTG curves data files is the best method, however, discussing other thermal analytical curves (DTA and TDA), can complete the information found by means of chemometric processing of whole TG and DTG curves.

The Hydrothermal Stability of Alkali-Activated Fly Ash/Slag Pastes by the Incorporation of Cement Kiln Dust

This paper deals with hydrothermal stability of inorganic aluminosilicate polymers, which were prepared by mixing blast furnace slag, fly ash and cement kiln dust in ratio 4:2:1. Cement kiln dust was used as alkaline activator with 4M sodium hydroxide solution. Samples were cured under hydrothermal conditions up to 170 °C for 24h and changes in mechanical properties, phase composition and porosity were monitored. During the hydrothermal process, the formation of zeolite from cancrinite group was monitored. The effect of the change of composition on the thermal expansion/shrinkage was studied by thermal dilatometry. Autoclaved samples were subjected to significant irreversible shrinkage during heating to 900 °C.

Dilatometry and DTA Analyses of a Sample Made of Ni Base Super Alloy with a ZrO2/20%Y2O3 Ceramic Layer

This paper presents the results of dilatometry and DTA analyses performed on a Ni base super alloy sample on which a ZrO2/20%Y2O3 coating was deposited. The tests were done at similar temperatures as those present in a gas turbine engine at the inlet of the turbine. The purpose is to assess how a turbine blade with a ZrO2/20%Y2O3 coating would behave to changes in volume due to temperature and structural changes. The differential thermal analyses and thermo gravimetric analyses were performed on the DTA PT 1600 Linseis installation. The thermal dilatometry was performed on the L75HX XXXX installation.