Carbon Product
A carbon product is made of mesocarbon microbeads and graphite. Preferably, the weight percent of mesocarbon microbeads is 50-99% and the weight percent of graphite is 1-50%. Preferably, when the graphite is carbon-graphite, the carbon product has a density in the range of 1.6-1.8 g/cm 3 and a resistivity in the range of 2000-8000 μΩ·cm. Preferably, when the graphite is electro-graphite, the carbon product has a density in the range of 1.85-1.95 g/cm 3 and a resistivity in the range of 500-2000 μΩ·cm. The carbon product may be a carbon brush, a carbon bearing, a carbon seal or a brush contact member for a commutator of an electric motor.
1 . A commutator for an electric motor, comprising:
a base made of insulation material;
an electrically conductive member fixed to the base, the electrically conductive member comprising a plurality of bars each with a tang for connection of a lead wire of the motor; and
a contact member forming a brush contact surface, the contact member comprising a plurality of segments each electrically connected with a corresponding bar, the contact member comprising mesocarbon microbeads and graphite.
2 . The commutator of claim 1 , wherein in the contact member the weight percent of mesocarbon microbeads is 1-99% and the weight percent of graphite is 1-99%.
3 . The commutator of claim 1 , wherein in the contact member the weight percent of mesocarbon microbeads is 50-99% and the weight percent of graphite is 1-50%.
4 . The commutator of claim 1 , wherein in the contact member the weight percent of mesocarbon microbeads is 70-80% and the weight percent of graphite is 20-30%.
5 . The commutator of claim 1 , wherein the graphite is natural graphite.
6 . The commutator of claim 1 , wherein the graphite is artificial graphite.
7 . The commutator of claim 1 , wherein the diameter of the mesocarbon microbeads is less than 150 μm.
8 . A method of making a carbon product, comprising:
mixing mesocarbon microbeads and electrographite;
iso-static pressing the mixed mesocarbon microbeads and electrographite to form a blank;
sintering the blank;
graphitizing the sintered blank; and
machining the graphitized blank to form a predetermined shape of the carbon product.
9 . The method of claim 8 , further comprising sieving the mesocarbon microbeads to choose the mesocarbon microbeads with size less than predetermined size before the mixing step.
10 . The method of claim 8 , wherein the step of sintering the blank comprises sintering the blank such that the sintered blank has a density in the range of 1.85-1.95 g/cm 3 and a resistivity in the range of 500-2000 μΩ·cm.
11 . A method of making a carbon product, comprising the steps of:
mixing together powdered mesocarbon microbeads and powdered carbon-graphite;
kneading the mixed mesocarbon microbead and graphite powder;
compressing the mixed powder to form a blank;
sintering the blank; and
machining the sintered blank to form the carbon product.
12 . The method of claim 11 , wherein the method further comprises a step of sieving the powder after the kneading step and before the compressing step.
13 . The method of claim 12 , wherein the method further comprises a step of mixing the powder after the sieving step and before the compressing step.
14 . The method of claim 11 , wherein the step of sintering the blank comprises sintering the blank such that the sintered blank has a density in the range of 1.6-1.8 g/cm 3 and a resistivity in the range of 2000-8000 μΩ·cm.
15 . A carbon product made of mesocarbon microbeads and graphite, wherein the weight percent of mesocarbon microbeads is 50-99% and the weight percent of graphite is 1-50%.
16 . The carbon product of claim 15 , wherein the weight percent of mesocarbon microbeads is 70-80% and the weight percent of graphite is 20-30%.
17 . The carbon product of claim 15 , wherein the carbon product is a product selected from the group consisting of: a carbon bearing; a carbon brush; a carbon seal; and a brush contact surface of a commutator.
18 . The carbon product of claim 15 , wherein the carbon product has a density in the range of 1.6-1.8 g/cm 3 and a resistivity in the range of 2000-8000 μΩ·cm.
19 . The carbon product of claim 15 , wherein the carbon product has a density in the range of 1.85-1.95 g/cm 3 and a resistivity in the range of 500-2000 μΩ·cm.