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    • 3. 发明授权
    • Process of making fine ceramic powders from aqueous suspensions
    • 从水性悬浮液制备精细陶瓷粉末的工艺
    • US5981445A
    • 1999-11-09
    • US668422
    • 1996-06-17
    • Jitka KirchnerovaDanilo Klvana
    • Jitka KirchnerovaDanilo Klvana
    • B01J23/00B01J37/32C01B13/14C01G3/00C01G37/00C01G53/00C04B35/45C04B35/50H01L39/00C01F17/00
    • C04B35/50B01J23/002B01J37/32C01B13/14C01G3/006C01G37/006C01G51/68C04B35/4508B01J2523/00C01P2002/34C01P2002/54C01P2002/72C01P2002/88C01P2006/12C01P2006/60Y10S977/776
    • The new preparation process for making fine high specific surface ceramic powders suitable as catalysts or precursors for ceramics uses lanthanum (or other rare earth lanthanide) oxide as one of the precursors. The oxide is mixed with water to form a liquid slurry, whereby it is transformed to the hydroxide by reaction with water. The resulting hydroxide slurry, which can be milled to reduce the particle size and to speed up the reaction, is then combined, while stirring vigorously to assure homogenous mixing, with a solution of required amount of remaining metal nitrate precursors, for example strontium and cobalt nitrates. The reaction between lanthanum hydroxide and transition metal nitrates produces a colored (color depending on the transition metal) slurry consisting of metal hydroxides suspended in aqueous nitrate solution with pH>2. This perovskite precursor slurry is spray-frozen and freeze dried. The freeze-dried material is transformed to perovskite by slow controlled calcination at temperatures above 550.degree. C. For example calcination 12 h at 585.degree. C. and subsequently 4 h at 620.degree. C. produces nearly phase pure perovskite having specific surface area of >10 m.sup.2 /g, depending on the composition. The perovskite precursor slurry can alternatively be processed first by spray-drying (instead of spray-freezing/freeze-drying) and subsequent calcination.
    • 用于制备适合作为陶瓷或催化剂前体的精细高比表面陶瓷粉末的新制备方法使用镧(或其它稀土镧系元素)氧化物作为前体之一。 将氧化物与水混合以形成液体浆料,由此通过与水反应将其转化为氢氧化物。 然后将所得氢氧化物淤浆(其可以研磨以减小粒度和加速反应)合并,同时剧烈搅拌以确保均匀混合,与所需量的剩余的金属硝酸盐前体(例如锶和钴)的溶液 硝酸盐 氢氧化镧和过渡金属硝酸盐之间的反应产生悬浮在pH> 2的硝酸盐水溶液中的金属氢氧化物组成的着色(颜色取决于过渡金属)浆料。 将该钙钛矿前体浆液喷雾冷冻并冷冻干燥。 通过在高于550℃的温度下缓慢控制煅烧将冷冻干燥的材料转化为钙钛矿。例如在585℃下煅烧12小时,随后在620℃煅烧4小时,产生几乎相纯的钙钛矿,比表面积> 10 m2 / g,取决于组成。 另外可以通过喷雾干燥(代替喷雾冷冻/冷冻干燥)和随后的煅烧来首先处理钙钛矿前体浆料。