 |
|||
      |
 |
|
Development of a technique of carrying out of tests and the device for research of thermal processes in substances of crystal structure Abstract Andrey D Borysenkov INTRODUCTION Recently the problem of the identification of various sorts of crystal substances, that may be dangerous for man, has been becoming vital. Such explosives can be different full-energy systems and mixtures combined on their basis. One of the methods for definiting these substances is the research of processes that are taking place during the heating and quantitative and qualitative estimation of them. Thus, problem appiars to create a device and a technique of investigation of thermal processes during the heating of crystal substances, and also accumulate a database about the quantitative estimation of these processes and to develop heuristic analysis methods for the identification of various compounds.
THERMAL METHODS OF SUBSTANCE ANALYSIS To carry out such researches various methods of the thermoanalysis are used. In this case, to solve this problem, a method of the differential scanning calorimetry (DSC) is used. The classical scheme of the DSC is represented in Figure 1. Fig. 1 – Scheme of a differential thermal analyzer
DEVELOPMENT OF DEVICE The device represented in Figure 2 has been developed in order to decide the problem menthianed above. Fig. 2 – Scheme of a laboratory device The device consists of the following parts: a thermode (1), thermocells (2), a unit of data gathering (3), a data link (4) and a personal computer (5). In this case the researches are made not during the heating of the substance, but during the process of its cooling. The feature of the device is also the absence of a reference sample. The dependence of the an unavailable reference temperature on the duration of the process in this case is replaced by two approximating curves – before and after the phase transition.
INTERMEDIATE RESULTS As a result of carrying out a series of experiments with the substance called resorcinium, the graphs have been received. With the help of their mathematical processing in the software package TableCurve the equations of approximation of the dependence of substance temperature on the time before the phase transition and after it (it is designated on Figure 3) have been received, and, using the received results, a value of heat of the phase transition of resorcinium, as well as the change of the system entropy have been calculated. So the heat of the transition is - 372,3 J/g, and the change entropy – 31,03 J/K. The divergence between the results in three experiment series average out 8,5 %. Figure 3 - Dependence of substance temperature on the time CONCLUSIONS Thus, in the work represented it has been made the development of the hardware-software device for carrying out the automated researches of some crystal substance thermal properties is made. The distinctive feature of the device developed is its low cost and apportunity to use some already proved methods of thermal analysis in a application i.e. the research of the explosives. As the modification of the installation described the following changes may be provided: the research of substance during its heating, the change of a furnace heating mode using the same microcontroller, and also the replacement of a thermode by a thermocouple that has doubtless advantages over the thermistor.
At the moment of writing the essay, work on the device is going on. All final results may be received from January, 2007 from the author or his supervisor, cender the agreement with the former. |
 |
||
