Promoted ignition-combustion is a term which has been used to describe a situation where a substance with poor oxygen compatibility ignites and supports the combustion of a more resistant material. Previous papers on the subject in recent years have reported on the investigation of this phenomenon as it relates to aluminum, carbon steel, stainless steels and a number of engineering alloys.
Aluminum alloys are used in the construction of equipment found in industrial gas applications. Yet, promoted ignition-combustion test data on aluminum samples showing the effects of variables such as test pressure, oxygen purity, promoter types, etc. on promoted ignition-combustion behavior of one aluminum alloy are scarce over the full spectrum of oxygen enriched atmospheres which might be encountered in the industrial gas business.
Titanium alloys are preferred materials of construction in certain environments where severe corrosion is of concern. However, there are known instances where they have proven to be incompatible with oxidizers such as liquid oxygen, gaseous oxygen, red fuming nitric acid and “red” nitrogen tetroxide. Recent developments in titanium alloys have been oriented towards improvement of their ignition resistance in oxygen enriched environments for specific applications.
In this investigation, the promoted-ignition combustion behavior of aluminum alloy 5183 was studied in oxygen-nitrogen gas mixtures over the pressure range of 0.1 MPa to 20.8 MPa with oxygen purities ranging from 40% to 99.7% using 3.175 mm diameter rods. Utilizing the same test method and specimen size, the promoted ignition-combustion resistance of a commercially pure titanium alloy and Nb-55Ti titanium alloy was studied in oxygen-nitrogen mixtures with oxygen purities ranging from 30 to 80% oxygen at pressures up to 1.5 MPa.