High-temperature corrosion of structural materials in N2O4

The mechanism of low-temperature corrosion of materials in the N2O4 medium at a temperature between 100 and 200 deg C under conditions of a circulating circuit is studied. The effect of an aggregate state of the coolant, pressure, HNO3 additions, corrosion products is analysed. New information about investigation methods of material corrosion in a liquid phase at pressures up to 160 atm is given. The effect of the coolant composition and various types of steel passivation on corrosion decrease is considered. The data on corrosion in ''nitrine'', the optimum composition of the coolant having a low corrosive effect are presented. It is shown that steels of various composition with a different grain size corrode in nitrine with a low, approximately the same rate. Phenomena of corrosion in a boiling coolant are considered. It is shown that the main factor which deteriorates material stability is the enrichment of the coolant with detrimental ad mixtures in its phase transition. Under these conditions, relation between the corrosion rate and steel composition is observed. Corrosion in commercially clean N2O4 in condensation is considered. It is shown that steels with high chromium content and being silicon-alloyed have increased stability and nickel base- and austenitic steels are subjected to intercrystalline corrosion. Cracking of titanium alloys is observed