With the growing metal consumption, with the growing raw material and energy prices, with the diminishing raw material and energy reserves, with the need for the high quality products, there is an everlasting demand on the optimization of the production processes, on the waste reduction and on the guaranteed quality. The bulk thermal analysis BTA enables to achieve or to come as near as possible to this goal in the metallurgical production.
The aim of the project is to develop the BTA system for the metallurgical (and also other) applications in several steps. The simplest BTA system consists of the forecasting expert system and the sampling device.
On the market is currently no commercial device, which would be capable to achieve the cooling curve adequate for the BTA of any melt. The base forecasting expert system is practically available from the shelf. But to be fully working, the system has to be customized - according to the aimed application, where the main task is the corresponding data base.
It is obvious, that for each particular alloy group a particular sampling device is to be used. The geometry, the material of the sampling device and the art of sampling are completely dependent of the melts to be examined. The geometry of the melt container is defined by the range of the useful solidification behavior of the melt under the investigation as well as of the material of which it is made. The last depends on the cooling rates to be aimed and of the compatibility with the melt. The sampling art - pouring or dipping - defines the thermal sensor configuration as well as the container holder and the corresponding manipulation mechanisms.
As far as the non-ferrous metals and alloys are concerned there are no particular technical difficulties to make an appropriate sampling device. Therefore even the container for the repeated multiple use can be made. Properly designed and handled, they augment the reproducibility and the precision of measurements.
As far as the cast irons are concerned, a pouring type device is feasible, but a dipping type is surely better. The pouring type - as already used for the common thermal analysis - is mostly convenient for the small production facilities. The reason is that the ladle probe handling is simpler and more convenient by the furnaces of lower capacity.
An especial case are the sampling devices for steel. Only the dipping type with an automatic manipulating mechanism can properly accomplish the task. Similar manipulators are actually commercially available but they have to be adapted for the melt container type desired.
The sand crucibles, with the sand bound with an organic binder and with the common type thermocouple can not be used. The combustion of the organic binder, causing the change of the temperature conductivity and the heat emission properties of the sand, maybe generating also a heat excess, has a substantial influence on the cooling conditions of the melt sample. The real solidification properties of the melt are screened. The combustion is also not reproducible and not homogeneous over the whole crucible surface. The falling off of the sand freed by the binder combustion makes any measuring completely unreliable.
The main project task is to develop and to test the sampling device for steels. Here is the special accent on the art of the temperature sensors and on their geometry. The temperature sensor should be inexpensive and expendable, with the simple geometry enabling to achieve the desired goal. The melt sample container for steels needs an especial design as also the appropriate construction material. The temperature sensors should be reliable at least to 1600 degrees C. Several types of devices (unpublished) were constructed but not yet tested. So it is one of the main goals of the task to develop the proper melt sample container for steels.
This type of device can be used, appropriately adapted, also for the cast and ductile irons.