Study On Integration And Application Of The Pulse-heating Time-of-flight Mass Spectrometric Analysis System

The quantity and existing status of gas elements such as O,N,H,Ar affect the performance of metals so much. Traditional inert gas fusion-infrared absorption method and thermo-conductivity method can not match the requirements of some new and special materials. As early as2004, the concept of inert gas fusion-Mass Spectrometric method has been raised by Professor Wang Haizhou of Central Iron&Steel Research Institute,China. According to the concept, the group verified the theory of this analysis method and made a choice of MS detector. The prototype of inert gas fusion-time of flight MS analyzer was setup.Based on the above investigation, the pulse-heating time-of-flight mass spectrometric system has been integrated and optimized, correction method of mass spectral interference between CO++and N+is established in this dissertation. Series studies are practiced on its applications of simultaneous analysis of O, N, H and Ar in iron&steel, titanium and its alloys, nano powders and deposited metal.First, gas circuit of inert gas fusion heating system is redesigned and the analyzing parameters are optimized. The coupled interface between heating furnace and MS detector is customized. The effects of the capillary on the analyzing results causing by mechanical structure, size and position in the ion source of mass spectrometer are studied. The specifications of the capillary are fixed. The response of MS detector under different carrier gases is tested. The foundation is setup for the choice of the carrier gas. The parameters of TOF-MS detector are optimized by summarizing and testing the former researches done by project. Standard gas calibration equipment is made to solve the difficulty of CRMs that contain Ar or He. On the above research, heating furnace, coupled interface, gas circuit, TOF-MS detector, control system are integrated together with application software. The sample product of pulse-heating-TOF MS analyzer is built, typed PMA-1000.During the application, it is found that when the content of oxygen is high, the interference from the double charged ion of CO, CO++(m/z=14), on N+(m/z=14) will influence the measurement precision of N a certain extent. According to the theory that under the same ion source, the abundances of fragment ions are stable, the mathematic interference correction method is established by measuring a series of CO-He standard gas mixtures with different contents on the mass spectrometer. Series titanium alloys and steel samples are analyzed using this correction method. Satisfied results are obtained.According to the analyzing demands of Ar in some special metals, a new method of Ar determination is established by inert gas fusion-time of flight mass spectrograph analyzer. Titanium alloys, nano powders and laser beam welding products are analyzed.