Changing in the integral pore size of the C/C composite under low-temperature oxidation

An analytical model is developed for obtaining qualitative and semi-quantitative estimates of changes in the integral pore size at the oxidation pro-cess of heterophase materials. The model was tested in the study of the C/C composite oxidation at 600°C with a mass loss up to 75 % wt. To quantify the structural degradation of the composite, the nature of the change in the size of the formed pores is analyzed.

Effect of magnesium and calcium on oxygen activity in model nickel melts at PAr = 0.1 MPa and analysis of nonmetallic inclusions

The EMF method was used to study the oxygen activity in nickel melts during the deoxidation of Mg/Ca (up to 0.2 wt.%) in the atmosphere of ultrapure Ar. The logarithmic dependences were expressed in the change a[O] from the concentrations of deoxidizers. A significant increase in the deoxidation capacity of Mg and Ca was shown in comparison with Al at a content of 0.05 wt.% of the deoxidizers in the metal. The morphology and composition of nonmetallic inclusions after deoxidation were studied and complex configurations of nonmetallic inclusions from 2 to 100 microns located along the grain boundaries were shown.

EFFECT OF AIR HEATING ON CONCENTRATION OF NITROGEN OXIDES IN COMBUSTION PRODUCTS OF GASEOUS FUELS

The formation probability of nitrogen oxides in combustion products of mixed blast-furnace and natural gases under different conditions of combustion was calculated. It has been found out that heating the air incoming into burners of high-temperature blast-furnaces sharply increases concentration of nitrogen oxides in combustion products (by 1.5-1.75 times). It was notices that in furnaces where temperature was less than 950-1000 °С, heating the air up to 400 °С increased NOx content in gases released to the atmosphere no more than by 20-23%, and oxide concentration was in limits of sanitary standards.

EVALUATION OF CONTENT OF NITROGEN OXIDES IN COMBUSTION PRODUCTS OF GASEOUS FUELS

Formation mechanisms of nitrogen oxides in combustion products of gaseous fuels with different calorific efficiency under different firing conditions have been studied. It was found out that most important factors that influence on the nitrogen oxide concentration in outgoing gases were a fuel firing temperature, a furnace temperature and heating the firing air that sharply (more than 1.5 time) increased content of nitrogen oxides in the combustion products.

TECHNOLOGY PERFECTION OF Р6М5 STEEL-MAKING IN ELECTRIC ARC FURNACE

A technology of Р6М5 steel-making by the method of remelting with oxygen blowing in electric arc furnace of capacity 20 t has been examined. To improve technical and economic characteristics of the furnace operation for a series of experimental-industrial melts a number of measures was proven. The measures resulted in a decrease in melt time, a reduction of melting loss and specific consumption of energy and oxygen.