公开(公告)号：US4818515A

公开(公告)日：1989-04-04

申请号：US102295

申请日：1987-09-25

申请人： Emiliano M. Ceresa ,  Antonio Gennaro ,  Paolo Cortesi

发明人： Emiliano M. Ceresa ,  Antonio Gennaro ,  Paolo Cortesi

IPC分类号： C01F7/02 ,  B01J21/04 ,  C01F7/44

CPC分类号： B82Y30/00 ,  C01F7/441 ,  C01P2004/03 ,  C01P2004/32 ,  C01P2004/54 ,  C01P2004/61 ,  C01P2004/62 ,  C01P2004/64 ,  C01P2006/10 ,  C01P2006/12 ,  C01P2006/14

摘要： Alpha-alumina consisting essentially of solid, spherical, non-aggregated particles, having a diameter from 0.06 to 2 .mu.m, a polydispersion index below 2.0, a total porosity below 0.3 cc/g, a specific surface area from 0.7 to 80 m.sup.2 /g, and an apparent density of the particles from 3.20 to 3.94 g/cm.sup.3. The alpha-alumina is prepared by a process consisting, in that an alpha-alumina precursor, having a water content from 2 to 33% by weight, at starting temperatures ranging from room temperature to 850.degree. C., and consisting essentially of solid spherical, non-aggregated particles, having a particle diameter from 0.07 to 2.3 .mu.m and a polydispersion index of .ltoreq.2.0, is subjected to a heat-treatment at temperatures ranging from 1130.degree. to 1700.degree. C., said precursor being instantaneously brought from the starting temperature to the treatment temperature, and by carrying out the treatment during times, as generally indicated in the accompanying FIG. 1 between straight lines (a) and (b), which are sufficient to convert the precursor to phase alpha, but not such as to cause breakages and/or aggregations; the resulting product being then brought again to room temperature by means of a non-instantaneous cooling of the order of at least 10 seconds.

摘要翻译： 基本上由固体，球形，非凝集颗粒组成的α-氧化铝，其直径为0.06至2μm，多分散指数低于2.0，总孔隙率低于0.3cc / g，比表面积为0.7至80m2 / g，颗粒的表观密度为3.20〜3.94g / cm 3。 α-氧化铝通过以下方法制备：α-氧化铝前体，其水含量为2-33重量％，起始温度为室温至850℃，基本上由固体球形 ，粒径为0.07〜2.3μm，分散指数为2.0的非凝集粒子在1130〜1700℃的温度下进行热处理，所述前体即时带入 从起始温度到处理温度，并且通过在时间期间进行处理，如附图中通常所示。 在直线（a）和（b）之间的直线（1），其足以将前体转化为α相，但不会导致断裂和/或聚集; 然后通过至少10秒的次数的非瞬时冷却将所得产物再次升至室温。

公开(公告)号：US4808397A

公开(公告)日：1989-02-28

申请号：US078088

申请日：1987-07-27

申请人： Enrico Albizzati ,  Emiliano M. Ceresa ,  Luciano Zaninetta

发明人： Enrico Albizzati ,  Emiliano M. Ceresa ,  Luciano Zaninetta

IPC分类号： C01B33/18 ,  C01B13/32 ,  C01B33/12 ,  C01B35/10 ,  C01F7/34 ,  C01F7/36 ,  C01G23/053 ,  C01G25/00 ,  C01G25/02 ,  C01B33/113 ,  C01G23/04

CPC分类号： C01B13/328 ,  C01B33/126 ,  C01B35/1036 ,  C01F7/34 ,  C01F7/36 ,  C01G23/053 ,  C01G23/0536 ,  C01G25/02 ,  C01P2004/32 ,  C01P2004/61 ,  C01P2004/62

摘要： A process for preparing spheroid particles of oxide compounds, having an average diameter of smaller than 3 microns. An emulsion is prepared of a hydrolyzable liquid oxide compound in a perfluoropolyether, the emulsion is reacted with water, water vapor or with a mixture, in any ratio, of water with a liquid miscible or immiscible with water so as to form an oxide hydrate which is recovered dried and calcined. Oxide compounds include oxides of Ti, Al, Zr, Si or B.

摘要翻译： 一种制备氧化物化合物的球形颗粒的方法，其平均直径小于3微米。 在全氟聚醚中制备可水解液体氧化物化合物的乳液，该乳液与水，水蒸汽或任何比例的水与液体可混溶或与水不混溶的混合物反应，以形成氧化物水合物 回收干燥并煅烧。 氧化物包括Ti，Al，Zr，Si或B的氧化物。

公开(公告)号：US4374118A

公开(公告)日：1983-02-15

申请号：US318413

申请日：1981-11-05

申请人： Giampiero Basile ,  Giancarlo Boero ,  Emiliano M. Ceresa ,  Franco Montino

发明人： Giampiero Basile ,  Giancarlo Boero ,  Emiliano M. Ceresa ,  Franco Montino

IPC分类号： C01G37/027 ,  G11B5/706 ,  H01F1/11

CPC分类号： G11B5/70636 ,  C01G37/027 ,  C01P2006/42

摘要： This invention relates to a process for stabilizing ferromagnetic chromium dioxide in respect of water and oxidizable organic compounds which it may contact in magnetic tapes. The process is applicable to a starting CrO.sub.2 having good magnetic properties, i.e. a coercive force not lower than about 400 Oersted, a maximum magnetic induction B.sub.m not lower than about 2500 gauss, and a magnetic induction B.sub.r not lower than about 1600 gauss. The CrO.sub.2 is subjected to a heat treatment at a temperature ranging from 300.degree. to 390.degree. C. in the presence of a gas stream not exerting any oxidizing or reducing action on the compounds of trivalent, tetravalent and hexavalent chromium. Suitable gases are, for example, nitrogen, helium and argon.

摘要翻译： 本发明涉及一种稳定铁磁性二氧化铬相对于水和可磁化有机化合物的方法，它可以在磁带中接触。 该方法适用于具有良好磁特性，即不低于约400奥斯特的矫顽力，不低于约2500高斯的最大磁感应Bm和不低于约1600高斯的磁感应Br的起始CrO 2。 在不对三价，四价和六价铬的化合物施加任何氧化或还原作用的气流的存在下，在300℃至390℃的温度范围内对CrO 2进行热处理。 合适的气体是例如氮气，氦气和氩气。