Gas Selective Absorption Performance Of Ti/Zr-based Non Evaporable Getter

The control of atmosphere in vacuum devices is of great significance to maintain its high life,high reliability and high-accuracy.Applying getter to absorb active gas can effectively maintain the vacuum state of the device.In this paper,by optimizing composition and microstructure of getter material,the applicability of getter in complex atmosphere environment was improved,and the selective control of gas in vacuum device was realized.The gas selective absorption properties of Ti-Mo,ZrVFe and TiZrV getters were analyzed by constant pressure method.The surface of Ti-Mo powders were modified by electroless plating method,and Ni/Ti-Mo getter was prepared by powder metallurgy pressing and sintering process.Al-ZrVFe getters were prepared by powder mixing sintering and melting approaches.The specific research contents are as follows:(1)By analyzing the absorption properties of Ti-Mo,ZrVFe and TiZrV getters for H2,N2,CO and CH4,it is found that the absorption properties of the getter materials for H2,CO,N2 and CH4 decrease sequentially.The ZrVFe getter has the worst absorption performance for the four gases,the TiZrV and Ti-Mo getters have similar absorption properties for non-hydrogen gases,and the TiZrV getter has the best H2 absorption performance.(2)The Ti-Mo powders were coated with Ni film effectively by method of electroless plating.By optimizing the electroless plating process,the Ti-Mo powders were well covered by Ni film with the thickness of 1.5 ?m and less content of free elementary substance Ni particles were exist after electroless plating for 45 min.After being molded and sitered at 870?,the Ti2Ni phase was formed with counter diffusion of the outermost layer of Ti particles and the Ni film.Compared with unmodified Ti-Mo powder,the as-prepared Ti2Ni/Ti-Mo getter displayed a better getter performance:The hydrogen absorption rate at 10 min increased by 34%,the oxygen absorption rate decreased by 54%,the hydrogen absorption capacity in 2 h increased by 37%,and the oxygen absorption capacity decreases by 22%,which showed a good property of hydrogen permeability and oxygen resistance.(3)Al-ZrVFe getter materials were prepared by mixed powder sintering and melting methods.The results show that the existence of elementary substance Al in Al-ZrVFe prepared by mixed powder sintering decreases the gas absorption performance of H2 and N2.The element Al exists as alloy phase in Al-ZrVFe prepared by melting method.With the increase of Al content,the main crystal phases of the Al-ZrVFe materials gradually changes from Zr+Zr(VaFe1-a)2 phases to Zr2Al+Al3V phases.The Al-ZrVFe getter prepared with 5 wt.%A1 shows the main crystal phases with Zr(VaFe1-a)2+Zr2Al phases,which has better H2 and N2 absorption performance than the Al-ZrVFe getter with Zr+Zr(VaFe1-a)2 phases or Zr2Al phase as the main crystal phase.Meanwhile,the gettering rate at 10 min of mixed gas(77 vol.%H2+23 vol.%N2)was enhanced by 70%and the absorption capacity in 2 h increases by 73%compared with that of the ZrVFe getter.