Preparation method of fluorescent ceramic containing aluminum oxide matrix and related fluorescent ceramic

[0005] In view of the defects of low thermal conductivity and low luminous efficiency of the prepared fluorescent ceramics in the above-mentioned prior art, the present i...

As described in the background technology, the preparation of fluorescent ceramics in the prior art is obtained by sintering fluorescent powder raw materials (i.e. various oxides), and has certain requirements for its translucency, and the fluorescent ceramics obtained in this way emit light The efficiency is obviously lower than that of phosphor powder prepared from the same raw material, and the thermal conductivity of YAG ceramics is low, which is very unfavorable for heat dissipation during use. The invention prepares fluorescent ceramics with alumina matrix, directly adopts existing commercial fluorescent powder as raw material, does not go through the steps of fluorescent powder preparation in the preparation process, and avoids various problems brought about by the growth process of fluorescent powder grains in the preparation of fluorescent ceramics. At the same time, through the selection of alumina with small particle size and the high-pressure treatment process, the alumina matrix of the fluorescent ceramics produced is dense and has high thermal conductivity, and the finished product has good heat dissipation performance.

Because the melting point of fluorescent powder and aluminum oxide is close, and slightly lower than the melting point of aluminum oxide (as the melting point of YAG is 1950 ℃, the melting point of aluminum oxide is 2050 ℃), in the preparation process, when aluminum oxide enters the liquid phase At the same time, the original structure of the phosphor powder is easily destroyed, and the luminous efficiency of the alumina-based fluorescent ceramics obtained in this way is low. In the present invention, the particle size of the alumina powder is much smaller than that of the phosphor powder by selecting the alumina powder and the phosphor powder with a suitable particle size, which reduces the temperature required for the alumina powder to enter the liquid phase without reducing the temperature required for the phosphor powder to enter the liquid phase. The temperature ensures that the phosphor powder can maintain a stable physical structure at the sintering temperature, so that the phosphor powder has the high luminous efficiency of the large particle size phosphor powder. In addition, the small particle size of alumina enables the high-pressure treatment in the preparation process to fully fill the pores in the fluorescent ceramics, which improves the density of the prepared fluorescent ceramics (thereby improving thermal conductivity and light transmission properties). In addition, the present invention introduces a magnesia-yttria mixed sintering aid in the preparation process, the sintering aid first enters the liquid phase during the sintering process, and promotes the alumina to enter the liquid phase at a lower temperature, which plays a role in promoting sintering. The role of the sintered body not only improves the thermal conductivity and light transmission performance of the sintered body, but also ensures that as much phosphor powder as possible is not affected by the high temperature during the sintering process, and the physical structure and surface morphology can be kept stable, thus making the phosphor The obtained ...