Ceramic discs and round bars, methods of manufacture and articles thereof

The present invention discloses a dual density disk comprising: a dense outer tube comprising alumina having a purity higher than 99%; and a porous core comprising alumina having a density lower than that of the dense outer tube; wherein the purity of aluminum oxide of the porous core body is higher than 99%. Also disclosed is a method comprising: filling a dense outer tube with a slurry comprising alumina powder and a pore forming agent; the compact outer pipe filled with the slurry is heated to 300-600 DEG C, so that the pore forming agent is activated; forming a porous core in the dense outer tube; and sintering the dense outer tube and the porous core body at 800-2000 DEG C once or in stages. 本发明公开了一种双密度圆盘，包括：一个致密外管，包含纯度高于99％的氧化铝；以及一个多孔芯体，包含密度低于致密外管密度的氧化铝；其中，所述多孔芯体的氧化铝纯度高于99％。本发明还公开了一种方法，包括：向致密外管中填充浆料，所述浆料包含氧化铝粉末和造孔剂；将填充浆料的致密外管加热到300-600℃，使造孔剂活化；在致密外管中形成多孔芯体；以及在800-2000℃下一次或分段烧结致密外管及多孔芯体。