국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	Friction,Wear and Electric Characteristics of Slip-ring Brush Materials for Space Applications Part 2:Evaluation by Slip-ring Simulation Tests
저자	Mineo SUZUKI, Mikio WATANABE, Makoto NISHIMURA, Jun NAKAGAWA
Keyword	Slip-ring; Electrical contact; Silver-based composite; Molybdenum disulfide; Niobium diselenide; Vacuum
URL	http://send.nal.go.jp/send/jpn/dlfile.php3/naltr01315?doctype=7&filetype=20&path0=naltr01315&path1=pdf&path2=naltr01315.pdf
보고서번호	NAL TR-1315
발행년도	1996,11
출처	NAL (National Aerospace Laboratory of Japan)
ABSTRACT	Wear and electric characteristics of hot-pressed Ag-MoS2-NbSe2 composites were evaluated in a vacuum environment in order to find the optimum brush material of a slip-ring for space applications.The composite brush was rubbed against a coin silver ring or a silver ring,simulating a brush/ring contact of a slip-ring.First,the effect of the contacting load was evaluated under an electric current of 1 A and a sliding speed of 75 mm/s.The loads tested were 0.2 N,0.6N and 1 N.The increase in load resulted in lower electrical contact resistance and noise,and less wear.Better cntact between the brush and the ring seemed to be responsible for the good performance.As the second step of the study,Ag-MoS2-NbSe2 composites with different contents of MoS2 and NbSe2 were evaluated under a load of 1 N and an electric current of from 1 A to 20 A.The best performance was obtained with an 85wt％Ag＋12.5wt％MoS2＋2.5wt％NbSe2 composite brush and a silver ring under both low-current(1A)and high-current(20A)conditions.The redemonstrated that this brush/ring combination is relevant for both a signal slip-ring and a power slip-ring.As the third step,the electric current density was increased up to 800 A/cm2,16 times higher than that used for current power slip-rings,to examine the feasibility of the best brush/ring material combination for future use as a high-power-transmission slip-ring.Electrical contact resistance,electrical noise,and temperature and wear of the brush became extremely high as the electric current density increased.However,increasing the contact pressure of the brush wa found to be very effective in lowering the electrical contact resistance and noise at high current density conditions.A high-electric current density of 800 A/cm2,with good electrical and wear resistance performance,was achieved at a contact pressure of 90 N/cm2.Finally,the performance in nitrogen gas was examined because ground tests of a slip-ring space use are carried out in nitrogen gas.Electrical contact resistance and noise,and wear of the brush were all higher in nitrogen gas than in a vacuum.However,the good performance was recovered when the environment was changed from nitrogen gas to a vacuum.The performance obtained with the selected 85wt％Ag＋12.5wt％MoS2＋2.5wt％NbSe2 composite brush and a silver ring was superior to that of slip-rings currently used for satellites,especially in terms of high-power transmission capability.The composite brush material developed in this study is a promising candidate for a high-power,small-sized,lightweight and long-lived slip-ring for future use in the space program to accomodate the increased power requirements.