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Microwave sintering preparation method of high purity silicon nitride ceramic lift tube for low-pressure casting

A technology of silicon nitride ceramics and low-pressure casting, which is applied in the microwave sintering preparation of high-purity silicon nitride ceramic riser pipes for low-pressure casting, and in the field of microwave sintering preparation of inorganic non-metallic material products, which can solve problems such as unseen sintering production , to improve the microwave absorption capacity, reduce the sintering temperature, and increase the surface area

Active Publication Date: 2014-11-26
HENGYANG KAIXIN SPECIAL MATERIAL TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] So far, there is no report on the application of microwave sintering technology to the sintering production of large-scale high-purity silicon nitride ceramic products

Method used

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  • Microwave sintering preparation method of high purity silicon nitride ceramic lift tube for low-pressure casting
  • Microwave sintering preparation method of high purity silicon nitride ceramic lift tube for low-pressure casting

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0054] The high-purity silicon nitride powder and boron oxide accounting for 0.5% of the mass of the high-purity silicon nitride powder are put into a ball mill for wet ball milling, and the obtained slurry is dried and granulated to D 50 Particles of 50 μm to 70 μm are placed in a rubber mold and formed under high pressure in a cold isostatic press with a forming pressure of 100 MPa. The formed riser body is placed on a machine tool for trimming. The trimmed size is length 600mm, the inner diameter is 50mm, the outer diameter is 60mm, and the outer diameter of the flange is 100mm, and then the trimmed riser body is put into the bottom feeding microwave bell kiln for microwave sintering, and the body is placed under the same The microwave sintered structure is composed of alumina fiber cylinder, corundum mullite circular tube, graphite circular tube and graphite circular plate. The alumina fiber cylinder has a refractoriness of 1700°C and a density of 0.7g / cm 3 ; The corundu...

Embodiment 2

[0056] The high-purity silicon nitride powder and lithium hydroxide accounting for 1.0% of the mass of the high-purity silicon nitride powder are loaded into a ball mill for wet ball milling, and the obtained slurry is dried and granulated to D 50 Particles of 50 μm to 70 μm are placed in a rubber mold and molded under high pressure in a cold isostatic press with a molding pressure of 120 MPa. The formed riser body is placed on a machine tool for trimming. The trimmed size is length 900mm, the inner diameter is 100mm, the outer diameter is 130mm, and the outer diameter of the flange is 180mm, then the trimmed riser body is put into the bottom feeding microwave bell kiln for microwave sintering, and the body is placed under the same The pad firing ring of different materials, the microwave sintered structure is composed of alumina fiber cylinder, corundum mullite tube, graphite tube and graphite disc, among which the alumina fiber cylinder has a refractoriness of 1700°C and a de...

Embodiment 3

[0058] The high-purity silicon nitride powder and lithium carbonate accounting for 1.5% of the mass of the high-purity silicon nitride powder are loaded into a ball mill for wet ball milling, and the obtained slurry is dried and granulated to D 50 Particles of 50 μm to 70 μm are placed in a rubber mold and formed under high pressure in a cold isostatic press with a forming pressure of 150 MPa. The formed riser body is placed on a machine tool for trimming. The trimmed size is length 1200mm, the inner diameter is 150mm, the outer diameter is 180mm, and the outer diameter of the flange is 220mm, and then the trimmed riser body is placed in a bottom-feed microwave bell kiln for microwave sintering. The pad sintered powder of the same material, the microwave sintered structure is composed of alumina fiber cylinder, corundum mullite tube, graphite tube and graphite disc, among which the alumina fiber cylinder has a refractoriness of 1700°C and a density of 0.7g / cm 3 The corundum ...

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Abstract

The invention discloses a microwave sintering preparation method of a high purity silicon nitride ceramic lift tube for low-pressure casting. The preparation method comprises the following steps: placing silicon nitride powder and an additive in a ball milling machine, carrying out wet method ball milling to obtain material slurry, drying and granulating the slurry, placing the granules into a mould, pressing, and forming so as to obtain a lift tube blank; and placing the blank into a sintering cavity to carry out microwave sintering so as to obtain the high purity silicon nitride ceramic lift tube; wherein the sintering cavity is prepared by overlapping corundum and mullite round tubes and graphite round tubes, and the upper opening and the lower opening of the sintering cavity are both provided with a graphite round plate. The preparation method utilizes the special wave bands of microwaves to couple the silicon nitride composite material to generate heats, the material is consumed to heat the composite material as a whole, the optimized microwave sintered structure is matched with the structural characteristics of high purity silicon nitride ceramic lift tube, and thus the utilization rate and efficiency of microwaves is maximized. The preparation method has the advantages of good sintering quality, high yield rate, low sintering temperature, short sintering time, and low sintering energy consumption.

Description

technical field [0001] The invention relates to a microwave sintering preparation method of an inorganic non-metallic material product, in particular to a microwave sintering preparation method of a high-purity silicon nitride ceramic liquid riser for low-pressure casting. The invention belongs to the technical field of large-scale silicon nitride ceramic sintering and microwave heating. Background technique [0002] Silicon nitride ceramic material is a new type of ceramic material with a wide range of uses. It has very important applications in many industrial and household fields due to its excellent high temperature resistance, corrosion resistance, insulation, and thermal shock resistance. [0003] The liquid riser refers to the pipe that guides the liquid metal in the sealed crucible into the mold during low-pressure casting, and its main function is to divert and feed. As an important component in the gating system, it should ensure that the liquid metal flows smooth...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/66C04B35/584C04B35/64
Inventor 曾小锋李勇全
Owner HENGYANG KAIXIN SPECIAL MATERIAL TECH CO LTD
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