Determination of Nitrogen Content in Sponge Titanium, Titanium and Titanium Alloys

Nitrogen in titanium alloys mainly exists in the form of nitrides, such as TiN, VN, FeN, etc., and only a small part of nitrogen exists in the form of atoms. Excessive nitrogen content in titanium alloys will lead to loose macrostructure and even the formation of bubbles. It reduces the toughness, increases the hardness, and increases the sensitivity of the notch, which greatly hinders the application of titanium and titanium alloys. Therefore, in the production of titanium and titanium alloy tubing, it is necessary to accurately analyze the nitrogen content in sponge titanium, titanium, and titanium alloys, and strictly control its content to ensure product quality. Due to the high melting point of nitrides in titanium and titanium alloys (for example, the melting point of titanium nitride is 2950°C), it is difficult to directly determine its content by pulse inert gas melting method. Through the selection and combination of different graphite crucibles, fluxes, sample weights, and heating power, researchers have realized the use of LECO's TC600 oxygen and nitrogen combined detector pulse inert gas melting-thermal conductivity method to test sponge titanium, titanium, and Titanium Alloy Seamless Rectangular Pipe. Determination of nitrogen content.

The principle of the experiment is as follows: put the sample into a graphite crucible with flux, protect it with an inert gas (helium), and release oxygen and nitrogen at a sufficient temperature. Oxygen combines with carbon to form CO and nitrogen is released as N2. The gas released by the sample is carried by the inert gas through the heated rare earth copper oxide, so that CO is converted into CO2, H2 is converted into H2O, CO2 is absorbed by soda asbestos, and H2O is absorbed by anhydrous magnesium perchlorate. Then, nitrogen enters the thermal conductivity measurement cell in the form of N2, and the output of the Wheatstone bridge is integrated and compared with the reference material to respond, which is displayed in the form of nitrogen percentage.

The test results are as follows: using a high-temperature graphite crucible preloaded with 0.050g of high-purity graphite powder, and using a high-purity nickel basket as a flux, the best test conditions for the combined measuring instrument are: degassing power 5600W, analysis power 5000W, degassing time 20s, cooling time 15s, flushing time 15s, integration time 65s. Through the measurement of standard samples and comparison with the data of other units, and put into production testing, it is proved that the method is easy to operate, fast in analysis speed, and the accuracy and precision of data meet the needs of scientific research and production.