Complex oxide powder, friction material composition, and friction material

Abstract

A complex oxide powder contains cerium, zirconium, and aluminum and, has a specific surface area of 0.5 m2/g or more and 10 m2/g or less.

1 . A complex oxide powder comprising cerium, zirconium, and aluminum, and having a specific surface area of 0.5 m 2 /g or more and 10 m 2 /g or less,
 wherein:   a content of cerium is 40% by mass or more and 95% by mass or less in terms of oxide;   a content of zirconium is 0.1% by mass or more and 50% by mass or less in terms of oxide; and   a content of aluminum is 0.1% by mass or more and 10% by mass or less in terms of oxide.   
     
     
         2 . The complex oxide powder according to  claim 1 , wherein the complex oxide powder has a crystallite diameter of 100 nm or more and 800 nm or less. 
     
     
         3 . The complex oxide powder according to  claim 1 , wherein the complex oxide powder has a particle diameter D 50  of 0.5 μm or more and 20 μm or less. 
     
     
         4 . The complex oxide powder according to  claim 1 , wherein the complex oxide powder has a particle diameter D 99  of 60 μm or less. 
     
     
         5 . The complex oxide powder according to  claim 1 , wherein the complex oxide powder has a grain crushing strength of 50 N or more and 300 N or less. 
     
     
         6 . (canceled) 
     
     
         7 . The complex oxide powder according to  claim 1 ,
 wherein:   a content of cerium is 49% by mass or more and 91% by mass or less in terms of oxide;   a content of zirconium is 1% by mass or more and 43% by mass or less in terms of oxide; and   a content of aluminum is 1% by mass or more and 8% by mass or less in terms of oxide.   
     
     
         8 . The complex oxide powder according to  claim 1 , wherein the complex oxide powder comprises CeAlO 3 . 
     
     
         9 . The complex oxide powder according to  claim 1 , wherein the complex oxide powder comprises a rare earth element other than cerium. 
     
     
         10 . The complex oxide powder according to  claim 1 , wherein the complex oxide powder comprises 0.1% by mass or more and 5% by mass or less of a rare earth element other than cerium in terms of oxide. 
     
     
         11 . The complex oxide powder according to  claim 9 , wherein the rare earth element other than the cerium is one or more selected from the group consisting of yttrium and lanthanum. 
     
     
         12 . The complex oxide powder according to  claim 1 , wherein the complex oxide powder comprises an alkaline earth element. 
     
     
         13 . The complex oxide powder according to  claim 1 , wherein the complex oxide powder is used for a friction material. 
     
     
         14 . A friction material composition comprising a friction modifier, a fiber base material, and a binder, wherein the friction material composition comprises the complex oxide powder according to  claim 1  as the friction modifier. 
     
     
         15 . The friction material composition according to  claim 14 , wherein a content of the complex oxide powder is 5% by mass or more and 20% by mass or less when a total of the friction material composition is 100% by mass. 
     
     
         16 . A friction material comprising a molded body composed of the friction material composition according to  claim 14 . 
     
     
         17 . The friction material according to  claim 16 ,
 wherein:   a first fade test measured under the following measurement condition A is performed 9 times in accordance with the Japanese Automobile Standard Organization JASO C406; and   an average value of a maximum value μ value and a minimum value μ value when a minimum friction coefficient is indicated is calculated in an obtained behavior peak, and the average value is 0.20μ or more.   
       <Measurement Condition A>
 Braking initial speed: 100 km/h 
 Braking interval: 35 seconds 
 Brake temperature prior to braking during first measurement: 80° C. 
 Braking deceleration: 0.45 G 
 Braking frequency: 9 
 
     
     
         18 . The friction material according to  claim 16 , wherein a lapping μ value, which is an average value of friction coefficients measured under the following measurement condition B in accordance with the Japanese Automobile Standard Organization JASO C406, is 0.40 or more.
 <Measurement Condition B>
 Braking initial speed: 65 km/h 
 Brake temperature prior to braking: 120° C. 
 Braking deceleration: 0.35 G 
 Number of measurements: 200 
 
 
     
     
         19 . The friction material according to  claim 16 , wherein, when a friction coefficient X is an average value of friction coefficients measured 8 times in a second effectiveness test under the following measurement condition C in accordance with the Japanese Automobile Standard Organization JASO C406, and a friction coefficient Y is an average value of friction coefficients measured 8 times in the second effectiveness test under the following measurement condition D in accordance with the Japanese Automobile Standard Organization JASO C 406, a difference between the friction coefficients [(friction coefficient X)−(friction coefficient Y)] is 0.12 or less.
 <Measurement Condition C>
 Braking initial speed: 100 km/h 
 Brake temperature prior to braking: 80° C. 
 Braking deceleration: 0.2 G 
 Number of measurements: 8 
 
 <Measurement Condition D>
 Braking initial speed: 100 km/h 
 Brake temperature prior to braking: 80° C. 
 Braking deceleration: 0.7 G 
 Number of measurements: 8