| 摘要 |
PROBLEM TO BE SOLVED: To obtain an electroviscous fluid which exhibits higher induced shear stress and electroviscous effects than those of a nonaq. electroviscous fluid propd. by using a conventional carbon powder by using a zinc oxide powder contg. a specified amt. of a doping metal such as Al, So, or To. SOLUTION: At least one metal element selected from among Al, So, To, Cr, Mn, Fe, Co, Ga, Ge, Zr, In, Sn, and Hf is used as a doping metal and is added in an amt. of 0.1-25atom%. A zinc oxide powder (average size of 0.05-10μm) contg. the doping metal is prepd. by, preparing an acidic aq. soln. contg. zinc chloride an a chloride of the doping metal, adding an alkali (including ammonia to the soln. to hydrolyze the chlorides to coprecipitate zinc hydroxide and a hydroxide of the doping metal, and baking the coprecipitate to form oxides. An electroviscous fluid is prepd. by dispersing 5-50wt.% prepd. zinc oxide powder in 50-95wt.% oily medium (e.g. a hydrocarbon oil) pref. having a viscosity (25 deg.C) of 500cSt or lower. |
