The publication presents the results of examination of selected carburizers used for cast iron production with respect to their electric

resistance. Both the synthetic graphite carburizers and petroleum coke (petcoke) carburizers of various chemical composition were

compared. The relationships between electrical resistance of tested carburizers and their quality were found. The graphite carburizers

exhibited much better conductivity than the petcoke ones. Resistance characteristics were different for the different types of carburizers.

The measurements were performed according to the authors’ own method based on recording the electric current flow through the

compressed samples. The samples of the specified diameter were put under pressure of the gradually increased value (10, 20, 50, 60, and

finally 70 bar), each time the corresponding value of electric resistance being measured with a gauge of high accuracy, equal to 0.1μΩ.

The higher pressure values resulted in the lower values of resistance. The relation between both the thermal conductance and the electrical

conductance (or the resistance) is well known and mentioned in the professional literature. The results were analysed and presented both in

tabular and, additionally, in graphic form.

In this work, research on influence of multiwalled carbon nanotubes (MWCNTs), produced in Catalic Chemical Carbon Vapor Deposition, NANOCYLTM NC7000CNTs on a structure and properties of AISI 301 steel remelted by TIG arc. In the assessment of influence a type of carbon on properties and structure of austenitic steel, as a carbon filler was use also carburizer. In the specimens (AISI 301 plates) with dimensions 155×60×7 [mm] were drilled holes with 1.3 mm diameter and placed 0.5 mm under specimen surface. Next, to the drilled holes was implemented CNTs, carburizer and mixture of these both powders. Prepared specimens were remelted by TIG method on the CASTOTIG 2200 power source with 2.4 mm tungsten thoriated electrode with parameters sets for obtain 3.0 mm penetration depth. Remelted specimens were cut into the half of the welds distance and prepared for metallographic examinations. Cross sections of the specimens were tested on classical metallography microscopes, hardness tests, SEM analyses (on JEOL 5800 LV SEM EDX equipment) and phase identification by X-ray phase analysis on Philips APD X’Pert PW 3020 diffractometer. Hardness analysis indicates about 25% increase of hardness in the remelted area when the CTNs are used. In the specimens with carburizer there is no significant changes. SEM analyses of remelted areas on AISI 301 specimens modificated with CNTs, indicates that dark areas, initially interpret as one of the phase (based on optical microscope) is finally densely packed bladders with dimensions from 50 nm up to a few µm. These bladders are not present in the specimens with carburizer filler. High resolution scanning microscopy allow to observe in the this area protruding, longitudinal particles with 100-300 nm length. For identification of this phase, X-ray analysis was done. But very small dimensions of used CNTs (diameters about 9,5 nm), random orientation and small weight amount can make difficult or impossible to CNTs detection during XRD tests. It means that it is not possible to clearly determine nature of particles filling the cavities, it is only possible to suppose that they are CNTs beams with nanoparticles comes from their disintegration. Results of the researches indicates, that fill in the weld pool with different form of carbon (CNTs and carburizer) it is possible to achieve remelted beads with different structure and hardness distribution. It confirms validity of the research continuation with CNTs as a modifier of steels and also other metals and theirs alloys.