Preparation method of large-size Al2O3 polycrystal

Abstract

The invention relates to a preparation method of a large-size Al2O3 polycrystal, in particular to a process flow for forming a high-purity and high-volume-density Al2O3 polycrystal in a process of preparing a large-size Al2O3 polycrystal in a cylindrical cold crucible with an inner diameter of phi 150-230mm, a height of more than 500mm and a thickness of 15-30 mm. The process flow comprises the following steps of: preparing a crucible, adding raw materials and adding and placing a kindling in the early stage of smelting; and controlling ignition of the kindling and melting of the raw materialsin the initial stage of smelting. A relative position between a melting liquid surface and a heating induction coil is controlled in the middle and later stages of smelting. The invention provides apreparation method of an Al2O3 polycrystal, which is simple and safe to control and operate, through in-depth analysis of factors such as selection of a starting kindling, laying of the starting kindling, ignition, heating, temperature control and material adding, and the prepared Al2O3 polycrystal is high in purity, high in density and large in size.

Description

technical field

[0001] The present invention relates to Al 2 o 3 The preparation process of polycrystals, specifically relates to the preparation of large-sized Al 2 o 3 Formation of high purity, high bulk density Al in polycrystalline process 2 o 3 Polycrystalline process flow. Background technique

[0002] al 2 o 3 Single crystal is widely used in many industries due to its excellent comprehensive performance. Especially because of its unique lattice structure, excellent mechanical properties, and good thermal properties, Al 2 o 3 Crystals become the semiconductor GaN / Al for practical applications 2 o 3 Light-emitting diodes (LEDs), large-scale integrated circuits SOI and SOS, and superconducting nanostructure thin films are the most ideal substrate materials.

[0003] With the development of science and technology, the preparation of Al 2 o 3 The quality of raw materials required for single crystals puts forward higher requirements. The early raw materials ...

Examples

Embodiment 1

[0022] 1. Before smelting, cover the inner wall of the cylindrical crucible with a layer of high-purity Al with a thickness of 5mm 2 o 3 Powder, the outer wall of the cylindrical crucible is covered with asbestos cloth, insulating board and insulating cloth tape, and the heating induction coil is fixed on the outer wall of the crucible. The inner diameter of the cylindrical crucible is Φ150mm, the height is 600mm, and the thickness is 20mm. First add a layer of high-purity Al with a thickness of 3cm to the bottom of the crucible 2 o 3 Cake material, then add 10cm high high-purity Al 2 o 3 Powder, adjust the height of the crucible to make high-purity Al 2 o 3 The upper surface of the powder is level with the middle of the heating induction coil. Dig a 2cm wide and 2cm deep annular deep groove inside the crucible at a distance of 5-8cm from the inner wall to place high-purity Al particles as a starting fire, and the high-purity Al particles are connected to each other to ...

Embodiment 2

[0027]The difference between this embodiment and Embodiment 1 is that the inner diameter of the cylindrical cold crucible is Φ230mm.

[0028] al 2 o 3 The density of single crystal is 3.8g / cm 3 . Preparation of Al by prior art 2 o 3 The raw material of single crystal is mostly Al 2 o 3 For powder and block materials, the loose stacking density is about 1.8g / cm 3 , the volume will be greatly reduced after smelting, and the productivity will be low. The raw material smelting of the present invention is sufficient, and the obtained Al 2 o 3 The purity of polycrystalline is high, and the bulk density is not less than 3.75g / cm 3 (near Al 2 o 3 single crystal density), can be directly used as the preparation of Al 2 o 3 Raw materials for single crystals, Al prepared by this method 2 o 3 The polycrystalline size can reach 145mm in diameter and 450mm in height, which greatly improves the preparation of Al 2 o 3 Single crystal productivity, more suitable for growing b...

technical field

[0001] The present invention relates to Al 2 o 3 The preparation process of polycrystals, specifically relates to the preparation of large-sized Al 2 o 3 Formation of high purity, high bulk density Al in polycrystalline process 2 o 3 Polycrystalline process flow. Background technique

[0002] al 2 o 3 Single crystal is widely used in many industries due to its excellent comprehensive performance. Especially because of its unique lattice structure, excellent mechanical properties, and good thermal properties, Al 2 o 3 Crystals become the semiconductor GaN / Al for practical applications 2 o 3 Light-emitting diodes (LEDs), large-scale integrated circuits SOI and SOS, and superconducting nanostructure thin films are the most ideal substrate materials.

[0003] With the development of science and technology, the preparation of Al 2 o 3 The quality of raw materials required for single crystals puts forward higher requirements. The early raw materials ...

Examples

Embodiment 1

[0022] 1. Before smelting, cover the inner wall of the cylindrical crucible with a layer of high-purity Al with a thickness of 5mm 2 o 3 Powder, the outer wall of the cylindrical crucible is covered with asbestos cloth, insulating board and insulating cloth tape, and the heating induction coil is fixed on the outer wall of the crucible. The inner diameter of the cylindrical crucible is Φ150mm, the height is 600mm, and the thickness is 20mm. First add a layer of high-purity Al with a thickness of 3cm to the bottom of the crucible 2 o 3 Cake material, then add 10cm high high-purity Al 2 o 3 Powder, adjust the height of the crucible to make high-purity Al 2 o 3 The upper surface of the powder is level with the middle of the heating induction coil. Dig a 2cm wide and 2cm deep annular deep groove inside the crucible at a distance of 5-8cm from the inner wall to place high-purity Al particles as a starting fire, and the high-purity Al particles are connected to each other to ...

Embodiment 2

[0027]The difference between this embodiment and Embodiment 1 is that the inner diameter of the cylindrical cold crucible is Φ230mm.

[0028] al 2 o 3 The density of single crystal is 3.8g / cm 3 . Preparation of Al by prior art 2 o 3 The raw material of single crystal is mostly Al 2 o 3 For powder and block materials, the loose stacking density is about 1.8g / cm 3 , the volume will be greatly reduced after smelting, and the productivity will be low. The raw material smelting of the present invention is sufficient, and the obtained Al 2 o 3 The purity of polycrystalline is high, and the bulk density is not less than 3.75g / cm 3 (near Al 2 o 3 single crystal density), can be directly used as the preparation of Al 2 o 3 Raw materials for single crystals, Al prepared by this method 2 o 3 The polycrystalline size can reach 145mm in diameter and 450mm in height, which greatly improves the preparation of Al 2 o 3 Single crystal productivity, more suitable for growing b...

Images