Sliding member

#The present invention relates to a sliding member, and specifically relates to a sliding member including a back-metal layer and a sliding layer made of a synthetic resin.

#A sliding member which includes a back-metal layer made of a metal and a sliding layer made of a resin composition coated on the back-metal layer has been used in a bearing or the like. Such resin composition for the sliding member has been known that incudes carbon fiber particles dispersed in a synthetic resin to improve wear resistance and strength of the sliding layer (see, for example, JP 10-204282A and JP 2013-194204A). The resin composition including carbon fiber particles dispersed in a synthetic resin has been also proposed for a multilayer bearing in which a porous layer is formed on a steel plate or the like and the porous layer is impregnated and coated with a resin composition including a synthetic resin such as PTFE. For example, carbon fibers are dispersed in a synthetic resin for the purpose of improving wear resistance in JP 2001-132756A and for the purpose of improving strength of a resin layer in JP 2010-159808A.

#The dispersion of carbon fibers in a synthetic resin has advantages in that high hardness of the carbon fibers improves wear resistance and that a fibrous shape of the carbon fibers improves strength of a sliding layer made of the synthetic resin. However, in some cases, excessively high hardness of the carbon fibers damages a counter shaft. Furthermore, there are following problem. Even when the synthetic resin matrix is worn, the carbon fibers are not worn. Thus, when the synthetic resin matrix is further worn, the carbon fibers protrude from a sliding surface of the sliding layer, and the carbon fibers fall off from the synthetic resin. The carbon fibers that have fallen off from the synthetic resin enter the space between the sliding surface and the counter shaft to accelerate abrasive wear.

#FIG. 1 is a diagram showing a cross section of a sliding member according to an embodiment of the present invention.

#FIG. 2 is a diagram showing a cross section of a sliding member according to another embodiment of the present invention.

#FIG. 3 is a diagram explaining an aspect ratio of a fibrous particle.

#FIG. 1 schematically shows a cross section of an embodiment of a sliding member 1 according to the present invention. The sliding member 1 includes a sliding layer 3 on a back-metal layer 2. In the sliding layer 3, fibrous particles 5 are dispersed in a synthetic resin 4. A surface 7 of the sliding layer 3 is a sliding surface 7.

#The dispersion of the fibrous particles 5 in the synthetic resin 4 improves strength and load resistance of the sliding layer 3. A volume ratio of the fibrous particles 5 dispersed in the synthetic resin 4 is 1 to 15%. If the volume ratio of the fibrous particles 5 in the synthetic resin 4 is less than 1%, the effect of improving the strength of the sliding layer 3 is insufficient, and if the volume ratio of the fibrous particles 5 in the synthetic resin 4 is more than 15%, friction properties of the synthetic resin layer is deteriorated. When the volume ratio of the fibrous particles 5 in the synthetic resin 4 is 3 to 15%, the effect of the fibrous particles 5 dispersed in the synthetic resin 4 is enhanced, and when the volume ratio of the fibrous particles 5 in the synthetic resin 4 is 5 to 15%, the effect is further enhanced.

#The fibrous particles 5 are made of semi-graphite. The semi-graphite is a material that is formed by firing a carbonaceous substance at a temperature of not lower than 1800° C. but lower than 2000° C. The carbonaceous substance is amorphous carbon including carbon atoms by approximately 100%. The semi-graphite maintains a certain degree of hardness of the carbonaceous substance and also has a softness of graphite. The fibrous particles 5 are made of semi-graphite have a nano indenter hardness of 1000 to 5000 MPa.