|Title of Invention||
"SINTERED CERAMIC, SLIDE PART THEREFROM, AND PROCESS FOR PRODUCING SINTERED CERAMIC"
|Abstract||CERAMIC SINTERED BODY AND PROCESS OF PRODUCTION THEREOF H ABSTRACT 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 i^m and a solid lubricant B with a mean particle size of 10-70 (xm. o n S ' S L , J Mixing M Spray drying _ Screening _ Molding! Firing _ Lapping H8-10 ~i bo»mi".5ii n^^°°'^'^°°Q^p'^n^^°^'^'"^^'^n^Q^p^n^^'^^p''^^^n'^^^|
CERAMIC SINTERED BODY AND PROCESS OF PRODUCTION
W Technical Field
5  The present invention relates to a ceramic sintered body, and to a
process for production of such body. The present invention also relates to
sliding parts employing such a ceramic sintered body.
IP  Most sintered silicon carbides are extremely hard and exhibit
10 good lubricity when used with water lubrication, while their wear
resistance and chemical resistance are also excellent. They are
therefore widely used in sliding parts such as mechanical seals,
bearings and the like. For mechanical seal applications, in particular,
they may be used even in situations with a high PV value, which
15 represents the product of the contact pressure and rotation rate on the
sliding surface, and therefore sintered silicon carbides (silicon carbide
ceramics) are considered to be highly useful materials. Moreover, it is
jp^ well knovm that sintered silicon carbides can be used with even higher
PV values if pores are introduced therein.
20  Conventional sintered silicon carbides have exhibited
satisfactory properties against sliding friction when liquid films are
formed on the sliding surfaces (this will hereinafter be referred to as
"lubricated state"). However in the complete absence of liquid films
on sliding surfaces or with inadequate formation of liquid films, (this
25 will hereinafter be referred to as "non-lubricated state"), they create
solid friction and have therefore tended to cause seizing of sliding
^ P 1. A ceramic sintered body comprising silicon carbide as the parent material, a solid
lubricant A with a mean particle size of no greater than 5 ^im and a solid lubricant B
with a mean particle size of 10-70 ^m, containing the solid lubricant A at 3-10 parts
by weight and the solid lubricant B at 2-8 parts by weight with respect to 100 parts by
weight of the silicon carbide, the total content of the solid lubricant A and the solid
lubricant B in the ceramic sintered body being 5-15 parts by weight with respect to
100 parts by weight of the silicon carbide.
2. A ceramic sintered body as claimed in claim 1, wherein solid lubricant A and solid
lubricant B are composed of graphite.
3. A ceramic sintered body as claimed in any one of claims 1 or 2, 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 as claimed in any one of the claims 1 to 3, wherein solid
lubricant B is composed of artificial graphite.
5. A ceramic sintered body as claimed in any one of the claims 1 to 4, wherein the
relative density is 92% or greater.
6. A ceramic sintered body as claimed in any one of the claims 1 to 5, which is sintered
7. A ceramic sintered body as claimed in any one of the claims 1 to 6, wherein the
silicon carbide is aSiC. j
8. A sliding part employing a ceramic sintered body as claimed in any one of the claims
9. A process for the production of a ceramic sintered body, as claimed in any one of the
claims 1 to 7, production process comprising a step of firing a mixture containing
silicon carbide powder, a thermosetting resin and carbon black with a mean particle
^ ^ size of no greater than 150 nm, as well as artificial graphite with a mean particle size
of 10-70 nm.
10. A process as claimed in claim 9, wherein the mixture containing 2-8 parts by weight
of the carbon black with a mean particle size of no greater than 150 imi, 2-8 parts by
weight of the artificial graphite with a mean particle size of 10-70 |xm and 1-3 parts by
weight of a the thermosetting resin in terms of carbon, with respect to 100 parts by j
weight of the silicon carbide powder.
11. A process as claimed in claim 9 or 10, wherein the thermosetting resin contains a
phenol resin and/or furan resin.
Dated this lO"' day of July, 2008.
Hitachi ChemicahCompany, Ltd.
of Amarchand & Mangaldas &
Attorneys for the Applicant
|Indian Patent Application Number||6074/DELNP/2008|
|PG Journal Number||05/2014|
|Date of Filing||10-Jul-2008|
|Name of Patentee||HITACHI CHEMICAL COMPANY, LTD|
|Applicant Address||1-1, NISHI-SHINJUKU 2-CHOME, SHINJUKU-KU TOKYO 163-0449 JAPAN|
|PCT International Classification Number||C04B 35/565|
|PCT International Application Number||PCT/JP2007/053305|
|PCT International Filing date||2007-02-22|