摘要
真空工作腔内的残余氢气会对砷化镓功率放大器造成严重危害,在器件内部预置吸氢材料是解决这一问题的有效技术途径。由于砷化镓器件内部有低熔点的焊料,要求吸氢材料在使用时应避免高温激活处理程序。报道一种满足该要求的无需激活吸氢材料,该材料以吸氢量较大的钛箔作为基体材料,经酸洗处理后,采用磁控溅射工艺在其表面沉积一层钯膜。通过扫描电子显微镜(SEM)和X射线衍射(XRD)表征了Pd膜的表面及截面的微观形貌和晶体结构,通过X射线光电子能谱(XPS)分析了Pd膜的表面元素价态,利用定容法测试了材料的吸氢性能。结果表明,Pd/Ti样品的吸氢主体是Ti箔,合适的酸洗工艺可以有效去除Ti箔的氧化层,有利于提高材料的吸氢性能;Pd/Ti样品经真空退火处理更进一步提高吸氢性能。表面元素价态分析表明,经磁控溅射沉积的Pd膜为金属态。在Pd膜的保护作用下,样品经真空退火并暴露大气24 h后,在测试温度为27℃、测试氢压为1000 Pa条件下,仍具有较高的吸氢性能,12 h的累积吸氢量可达191.98 Pa·L·cm^(-2)。
The residual hydrogen in the vacuum working cavity would cause serious harm to the GaAs-based monolithic microwave integrated circuit power amplifiers.The effective way to solve the problem was to preset the hydrogen getters inside the devices.Hydrogen absorbing materials could absorb hydrogen by reacting with hydrogen on the metal surface with high activity,to ensure that the hydrogen concentration in the sealed devices was maintained at the normal level.Hydrogen getters made of active metals would form a metal passivation film on the surface when exposed to air,which hindered the hydrogen absorbing process.Therefore,it was necessary to activate the hydrogen absorbing materials at high temperatures before use to restore the active surface of the materials.However,the solder used in GaAs-based integrated circuits in phased array radars had a low melting point,and the traditional hydrogen absorbing materials could not meet the requirements of devices because of the high activation temperature.Therefore,it was necessary to develop new hydrogen absorbing materials without activation before use.A feasible idea was to design the hydrogen getter which had a doublelayer structure of hydrogen-absorbing layer and protective layer,to realize the characteristics of no activation before use.The titanium foil with high hydrogen absorption capacity was used as the base material.A Pd film was deposited on the surface of Ti foil by magnetron sputtering process,after being washing to remove the surface oil and pickling to remove the passivation layer,and the Pd/Ti hydrogen getter was prepared without activation before use.The surface morphologies of Ti foil before and after being pickling were analyzed by optical microscope(OM).The micromorphology,the distribution,the chemical states of surface elements and the crystal structure of Pd/Ti samples were analyzed by scanning electron microscope(SEM),energy dispersive analysis(EDS),X-ray photoelectron spectroscopy(XPS)and X-ray diffraction analysis(XRD).The hydrogen absorption performance of the material was tested by the Sievert’s method,and the hydrogen absorption performance of the material after vacuum annealing treatment and exposure to the atmosphere for 24 h was emphatically studied.The passivation layer on the surface of the Ti foil could be successfully removed by pickling pretreatment.The room temperature hydrogen absorption performances of Ti foil before and after being pickling were compared.The results showed that the hydrogen absorption capacity of Ti foil after being pickling was obviously improved under the same test conditions.However,without the protection of Pd film,Ti foil would not absorb hydrogen after about 3 h,which indicated that the surface of Ti foil was still passivated.In order to further improve and maintain the long-term hydrogen absorption performance of Ti foil,a layer of Pd film was deposited as a protective layer.SEM results showed that Pd film grew in a columnar shape,with the thickness of about190 nm.There was no obvious gap on the surface of Pd film,and the surface of Ti foil was completely covered by Pd film.EDS results showed that Pd films were evenly distributed on the surface of Ti foil.XPS results showed that the surface of Pd film was all in the metallic state,not oxidized,while the surface contained some adsorbed oxygen.The effect of Pd film on the hydrogen absorption performance of the sample was investigated.The hydrogen absorption properties of Pd/Ti samples at room temperature after vacuum annealing treatment and exposure to the atmosphere for 24 h were tested,and the hydrogen absorption properties of Ti foil after pickling treatment under the same conditions were also tested as a comparison.The results showed that Pd/Ti samples still possessed good resistance to atmospheric oxidation and excellent continuous hydrogen absorption performance after being exposed to the atmosphere for 24 h.Under the certain test conditions,the hydrogen absorption capacity of 12 h was 191.98 Pa·L·cm^(-2),and the pure Ti foil sample had almost no obvious hydrogen absorption performance after being exposed to the atmosphere for 24 h.It showed that the selective hydrogen permeability of Pd film played a good role in protecting the active surface of Ti foil.At the same time,because Pd film could catalyze the dissociation of hydrogen molecules,hydrogen molecules dissociated into hydrogen atoms on the surface of Pd,and were absorbed by Ti foil after passing through Pd film.Under the catalytic dissociation of Pd film,the hydrogen absorption rate of Pd/Ti sample was greatly increased.The crystal structures of Ti foil,Pd/Ti sample and Pd/Ti sample after hydrogen absorption with about 191.98 Pa·L·cm^(-2)were studied.The results showed that Pd had a face-centered cubic structure,and the deposited Pd film showed a good crystalline state.After Pd/Ti sample absorbed hydrogen,the diffraction peak of Ti disappeared,and the new main peak matched with TiH2with face-centered cubic structure,which indicated that Ti reacted with the absorbed hydrogen.The diffraction peak of Pd did not shift,and the hydride was not formed,which indicated that in the process of hydrogen absorption of Pd/Ti samples,the role of Pd film was mainly to permeate hydrogen,while Ti foil was the main body of hydrogen absorption.
作者
史志胜
熊玉华
吴华亭
杨志民
刘晓鹏
崔建东
Shi Zhisheng;Xiong Yuhua;Wu Huating;Yang Zhimin;Liu Xiaopeng;Cui Jiandong(State Key Laboratory of Advanced Materials for Smart Sensing,GRINM Group Co.Ltd.,Beijing 100088,China;GRIMAT Engineering Institute Co.Ltd.,Beijing 101402,China;General Research Institute for Nonferrous Met-als,Beijing 100088,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2022年第12期1567-1572,共6页
Chinese Journal of Rare Metals
基金
国家自然科学基金项目(51671034)资助。
关键词
吸氢材料
酸洗
磁控溅射
吸氢性能
hydrogen getters
acid treatment
magnetron sputtering
hydrogen absorption performance
