公开(公告)号：JPH0692714A

公开(公告)日：1994-04-05

申请号：JP26552492

申请日：1992-09-09

Applicant: TOSOH CORP

Inventor： OMICHI NOBUKATSU ,  YOSHIMIZU AKIHIRO ,  OKAI MICHIJI

IPC: B01J2/04 ,  B01J13/00 ,  C04B35/00 ,  C04B35/622

Abstract: PURPOSE:To produce a ceramic sintered compact having higher density and strength than a conventional one by compacting and sintering. CONSTITUTION:The objective slurry of ceramic powder is a slurry of ceramic powder mixed with a binder and contains =250mum diameter. The objective ceramic granules are produced by spray-drying the slurry.

公开(公告)号：JPH05246720A

公开(公告)日：1993-09-24

申请号：JP9981791

申请日：1991-04-05

Applicant: TOSOH CORP

Inventor： IWATA HIDEKAZU ,  OKAI MICHIJI ,  KAWAGUCHI TETSUJI

IPC: C01G25/02 ,  C04B35/48

Abstract: PURPOSE:To produce zirconium oxide particles capable of producing a high reliability zirconium oxide sintered compact having higher performance than a conventional one with respect to density, strength, etc., by compacting and sintering the resulting zirconium oxide particles. CONSTITUTION:When zirconium oxide particles are produced by calcining zirconia hydrate particles, a suspension of the zirconia hydrate particles is spray-dried to obtain spherical dry zirconia hydrate powder having 1.0-2.0g/cm bulk density and this powder is calcined. The objective zirconium oxide particles are produced.

公开(公告)号：JPH0558637A

公开(公告)日：1993-03-09

申请号：JP25284291

申请日：1991-09-05

Applicant: TOSOH CORP

Inventor： MATSUI KOJI ,  CHIKAMORI YUJI ,  OKAI MICHIJI

IPC: C01G25/02

Abstract: PURPOSE:To obtain a hydrated zirconia son having a large average particle diameter at a high rate of reaction in a short reaction time in a simple process by hydrolyzing an aqueous solution of a nonalkaline zirconium containing the hydrated zirconia. CONSTITUTION:An aqueous solution of a zirconium compound at pH

公开(公告)号：JPH04367513A

公开(公告)日：1992-12-18

申请号：JP16750291

申请日：1991-06-13

Applicant: TOSOH CORP

Inventor： IWATA HIDEKAZU ,  OKAI MICHIJI ,  KAWAGUCHI TETSUJI

IPC: C01G25/02

Abstract: PURPOSE:To obtain stabilized or partially stabilized zirconium oxide powder having improved stability when calcined at a calcination temperature of the conventional process or having a stability comparable to the conventional product even by calcining at a lower calcination temperature. CONSTITUTION:Stabilized or partially stabilized zirconium oxide powder is produced by calcining hydrated zirconia powder containing a stabilizer. The calcination is carried out by raising the temperature at a heating rate of

公开(公告)号：JPH04202016A

公开(公告)日：1992-07-22

申请号：JP32994590

申请日：1990-11-30

Applicant: TOSOH CORP

Inventor： UEMA TSUTOMU ,  MITSUI HIDEO ,  OKAI MICHIJI

IPC: C01G25/02

Abstract: PURPOSE:To uniformly control compsn. and particle diameter and to improve dispersibility by maintaining a constant concn. of a precipitate and a constant pH when a mixed aq. soln. contg. salts of Zr, Y, Ca, etc., is allowed to react with an alkali soln. and Zr oxide-based fine powder is produced from the resulting precipitate. CONSTITUTION:A mixed aq. soln. contg. water-soluble salts of Zr and one or more among Y, Ca, Mg and Ce is prepd. and allowed to react with an alkali soln. to form a precipitate. At this time, a constant pH is maintained in the reaction system and the constant concn. of the precipitate in the system is maintained from the beginning of the reaction to the end. The resulting precipitate is separated, dried and fired.

公开(公告)号：JPH04130012A

公开(公告)日：1992-05-01

申请号：JP24635290

申请日：1990-09-18

Applicant: TOSOH CORP

Inventor： IWATA HIDEKAZU ,  KUMA KIMITAKA ,  OKAI MICHIJI

IPC: C01B33/26

Abstract: PURPOSE:To obtain a mullite sintered body having superior strength, thermal stability and creep resistance by mixing an Al(OH)3 slurry with an aq. Na2SiO3 soln., adjusting the mixture to a specified pH, producing a precipitate and carrying out calcination. CONSTITUTION:An Al(OH)3 slurry having

公开(公告)号：JPH03193620A

公开(公告)日：1991-08-23

申请号：JP32945789

申请日：1989-12-21

Applicant: TOSOH CORP

Inventor： IWATA HIDEKAZU ,  KUMA KIMITAKA ,  OKAI MICHIJI

IPC: C04B35/18 ,  C01B33/26

Abstract: PURPOSE:To obtain a precursor of mullite having less unevenness capable of forming a sintered body excellent in strength by using an inexpensive material by mixing an aq. solution of acid aluminum compd. with pH-controlled aq. solution of sodium silicate. CONSTITUTION:The aq. solution of acid aluminum compd. is added to a pH- controlled solution of sodium silicate and mixed to obtain a precursor of mullite. The aq. solution of sodium silicate is controlled in pH by adding a neutralizer, and the solution is preferably controlled to pH3-10. The precursor of mullite or pulverized mullite is then calcinated in air at 1000-1600 deg.C to obtain a mullite powder with less variation in Al/Si than in the mullite precursor before calcination. The obtd. mullite powder is molded, or preferably first pulverized and then molded, and sintered at 1500-1800 deg.C to obtain a mullite sintered body with extremely little variation of Al/Si.

公开(公告)号：JPH03141154A

公开(公告)日：1991-06-17

申请号：JP27589889

申请日：1989-10-25

Applicant: TOSOH CORP

Inventor： IWATA HIDEKAZU ,  KUMA KIMITAKA ,  OKAI MICHIJI

IPC: C04B35/18

Abstract: PURPOSE:To obtain a mullite precursor reduced in unevenness of Al/Si ratio in micro level by continuing to stir while controlling ratio of an acidic Al compound in reaction system to Na2SiO3 before and after feeding the acidic AL compound and neutralizing the produced precipitate-containing aqueous solution. CONSTITUTION:A mullite precursor is produced according to the following method from a precipitate obtained by blending an aqueous solution of acidic Al compound with Na2SiO3 aqueous solution and neutralizing the blend: An aqueous solution of Na2SiO3 or aqueous solution of Na2SiO3 and acidic Al compound are stirred so that the acidic Al compound in reaction system may be excess to Na2SiO3 before finishing feed and ratio expressed in terms of Al2O3/SiO2 may be a ratio in mullite when the feed is over. Then the stirring is continued and after forming precipitation, the precipitate-containing aqueous solution is neutralized by NaOH aqueous solution. As a result, mullite precursor being about 70/30-74/26 in Al/Si ratio in micro level is obtained. Mullite powder obtained by drying the precursor is formed and then burned to provide the mullite sintered compact having excellent strength, etc.

公开(公告)号：JPH01230702A

公开(公告)日：1989-09-14

申请号：JP5597988

申请日：1988-03-11

Applicant: TOSOH CORP

Inventor： OKAI MICHIJI ,  OZAWA TAKESHI ,  KUBO TOMIYOSHI

IPC: B22F1/02 ,  C09D5/23 ,  C09D7/12 ,  G11B5/712 ,  H01F1/09

Abstract: PURPOSE:To obtain ferromagnetic iron powder having excellent dispersibility, orientability and stability in magnetic paint by treating the ferromagnetic iron powder with coupling agent in organic solvent after treating with oxygen and steam and regulating each content of organic solvent modified material and moisture in the iron powder after above treatment. CONSTITUTION:The ferromagnetic iron powder containing the iron manufactured with dry reduction method as main component, is oxidized to the surface thereof under gas atmosphere containing oxygen, and after that, the steam is brought into contact with it, to execute steam treatment and successively, treatment by using the coupling agent in the organic solvent of toluene, etc., is executed to this iron powder. As the coupling agent, silane series coupling agent, etc., of octyl trithoxysilane, etc., is used and at the time of this treatment, the active surface remaining on the surface of the above iron powder oxidizes the above solvent, to generate the organic solvent denaturated material. Therefore, it is necessary to adjust so that the above modified material content to the drying iron powder after executing the above surface- treatment is made to

公开(公告)号：JPH10185799A

公开(公告)日：1998-07-14

申请号：JP34959196

申请日：1996-12-27

Applicant: TOSOH CORP

Inventor： MATSUI KOJI ,  UEDA KUNIYOSHI ,  ARAKAWA TOSHIHIKO ,  OKAI MICHIJI

IPC: G01N17/00 ,  G01N21/84 ,  G01N33/38

Abstract: PROBLEM TO BE SOLVED: To obtain a method in which a degradation layer which progresses to the inside from the surface of a ceramic containing zirconia can be measured with good accuracy and easily by a method wherein the inside of the ceramic is observed under a microscope. SOLUTION: In a method, the degradation of a ceramic containing zirconia is detected in such a way that the inside of the ceramic is measured under a microscope. When it is measured, a sintered compact is cut as a pretreatment, a smooth face is formed by a grinding method, a polishing method or the like, and the face is observed under the microscope. When the degraded ceramic is measured, a degradation texture, in a sparse shape, which is clearly different from a dense texture is observed at the outside (surface layer) of the cut face, and a degradation texture which is identical to the dense texture is observed at its inside. It is estimated that the degradation texture in the sparse shape is formed when fine cracks occurring due to a change in the phase of crystal particles existing on the surface layer are gathered. Consequently, a dense texture which is not degraded can be discriminated clearly from a sparse texture which is degraded.