Sintered ceramic, slide part therefrom, and process for producing sintered ceramic
It is an object of the invention to provide a ceramic sintered body that has a dense structure and minimal cracking and that exhibits excellent sliding properties even in a non-lubricated state, as well as a process for its production and sliding parts that employ the same. According to a preferred mode, the sintered body of the invention comprises silicon carbide as the parent material and further contains a solid lubricant A with a mean particle size of no greater than 5 μm and a solid lubricant B with a mean particle size of 10-70 μm.
1. A ceramic sintered body comprising silicon carbide as the parent material, and also a solid lubricant A with a mean particle size of no greater than 5 μm and a solid lubricant B with a mean particle size of 10-70 μm, wherein the ceramic sintered body contains solid lubricant A at 4-10 parts by weight and solid lubricant B at 2-8 parts by weight with respect to 100 parts by weight of silicon carbide.
2. A ceramic sintered body according to claim 1 , wherein solid lubricant A and solid lubricant B are composed of graphite.
3. A ceramic sintered body according to claim 1 , wherein solid lubricant A is composed of graphite obtained by firing carbon black and graphite obtained by firing a thermosetting resin.
4. A ceramic sintered body according to claim 1 , wherein solid lubricant B is composed of artificial graphite.
5. A ceramic sintered body according to claim 1 , wherein the total content of the solid lubricant A and solid lubricant B in the ceramic sintered body of the invention is 5-15 parts by weight with respect to 100 parts by weight of silicon carbide.
6. A ceramic sintered body according to claim 1 , wherein the relative density is 92% or greater.
7. A ceramic sintered body according to claim 1 , which is sintered without pressure.
8. A ceramic sintered body according to claim 1 , wherein the silicon carbide is αSiC.
9. A sliding part employing a ceramic sintered body according to claim 1 .
10. A ceramic sintered body production process comprising a step of firing a mixture containing 2-8 parts by weight of carbon black with a mean particle size of no greater than 150 nm, 2-8 parts by weight of artificial graphite with a mean particle size of 10-70 μm and 2-3 parts by weight of a thermosetting resin in terms of carbon, with respect to 100 parts by weight of silicon carbide powder.
11. A ceramic sintered body production process according to claim 10 , wherein the thermosetting resin contains a phenol resin and/or furan resin.
12. A ceramic sintered body according to claim 1 , which contains spherical pores.
13. A ceramic sintered body according to claim 12 , wherein the spherical pores have a mean pore size of 40-100 μm.
14. A ceramic sintered body according to claim 1 , wherein the solid lubricant A and the solid lubricant B are either in grains of the silicon carbide as the parent material, between the grains, or both.