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Micro processing process for silicon nitride ceramic parts

A technology of silicon nitride ceramics and processing methods, which is applied in the field of ceramic parts processing, can solve problems such as difficulties, high hardness of silicon nitride, and limitations of micro-forming processes, and achieve the effect of increasing density

Inactive Publication Date: 2006-11-01
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, silicon nitride is hard and non-conductive, not to mention micromachining, even ordinary machining is difficult
In addition, due to the high sintering temperature required for silicon nitride (>1800°C), research on the micro-molding process using silicon nitride powder as a starting material is limited.

Method used

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  • Micro processing process for silicon nitride ceramic parts
  • Micro processing process for silicon nitride ceramic parts
  • Micro processing process for silicon nitride ceramic parts

Examples

Experimental program
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Effect test

Embodiment 1

[0027] Using commercially available Si (below 200 mesh, purity 99.99%) powder as a raw material, using silicon nitride balls and a tank lined with silicon nitride, it was ball milled in pure ethanol for 48 hours to obtain a powder with an average diameter of about 5 μm. The Si powder after ball milling is vacuum-dried, filled into a graphite mold, and pre-sintered at about 1250°C using a plasma discharge sintering machine (SPS). The heating rate of SPS is controlled at 100°C / min, and the temperature is lowered after being kept at about 1250°C for 3 minutes. The SPS flake samples were 30 mm in diameter and approximately 5 mm thick. The relative density of the sample after pre-sintering is 80.6%.

[0028] The SPS pre-sintered body was precisely machined into a micro rotor using a high-speed micro milling machine (F-MACH 442, manufactured by Toshiba Machine). The milling machine used here can achieve 5-axis control, the spindle speed is as high as 60000rpm, and the rotation dev...

Embodiment 2

[0031] The calcined temperature was 1100°C, and other conditions were the same as in Example 1 to prepare a silicon calcined body. The relative density of the silicon powder after calcining was 70%, and a micro-hole array was processed on the sheet using a micro electric discharge machining device. Micro-EDM uses tungsten wire as the processing electrode to perform EDM on silicon pre-fired thin slices in air. For a thin sheet with a thickness of about 1.5 mm, a hole can be punched in less than about 1 minute. Figure 3 shows the scanning electron micrographs of the processed micropores. It can be seen that the shape of the micropores is relatively regular, and the inner surface is relatively smooth. The workpiece is placed in a silicon nitride crucible lined with BN powder, and the nitriding reaction is carried out simultaneously with other silicon powders in an industrial nitriding furnace. It was kept at a nitriding temperature of 1360° C. for 1 day. Figure 4 Shown is a s...

Embodiment 3

[0033] The calcining temperature is 1300° C., other conditions are the same as in Example 1, and the relative density of the silicon powder after calcining is 85%. And use a high-speed micro-milling machine (F-MACH 442, manufactured by Toshiba Machinery) to process a micro-rotor (flat plate, equivalent to 2.5 dimensions) smaller than that of Example 1. The micro-rotor is placed in a silicon nitride crucible lined with BN powder, and the nitriding treatment is carried out in the temperature range of 1330-1450 °C. Figure 5 Shown is a scanning electron micrograph of the rotor after nitriding reaction. The diameter of the sample is 5mm, the thickness is 1.2mm, and the thinnest part of the blade is only 70μm. Dimensional measurements before and after reaction sintering showed less than 1% shrinkage in the radial and thickness directions. Such as Figure 6As shown, X-ray diffraction analysis shows that after reaction sintering, the main component of the micro-rotor is α-Si 3 N ...

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Abstract

The invention relates to a micro-machining method of a silicon nitride ceramic component, which relates to a processing technology of a micro-component of a silicon nitride ceramic with high temperature resistance, oxidation resistance and high hardness. The method mainly includes three parts: (1) using hot pressing or plasma discharge sintering technology to pre-sinter the Si powder and control the density at 70-85%; (2) using precision machining or micro electric discharge machining Or photolithography and reactive ion etching and other silicon micromachining techniques are used to micro-process the Si powder pre-sintered body; (3) heat the micro-processed Si powder pre-sintered body parts in nitrogen to cause nitriding reaction to occur, Thus reaction sintering to obtain Si 3 N 1 Ceramic micro components. The invention combines the characteristics of micromachining and reaction sintering of silicon nitride ceramics, thereby realizing the micromachining and micromolding of silicon nitride ceramic microcomponents, and can increase the density by about 22%. It is very suitable for the preparation of microcomponents.

Description

technical field [0001] The invention belongs to the technical field of processing ceramic parts, and in particular relates to a method for processing a silicon nitride ceramic miniature part with high temperature resistance, oxidation resistance and high hardness. Background technique [0002] Silicon nitride (Si 3 N 4 ) Ceramics have the advantages of high strength, high temperature resistance, good oxidation resistance, and light weight. In recent years, their application in microelectromechanical systems (MEMS) technology has attracted attention. Because MEMS technology is developed on the basis of microelectronics technology, silicon wafer is an important MEMS material so far. The micro-processing technology of silicon wafers is quite mature, and single crystal silicon wafers can be processed into two-dimensional or three-dimensional microstructures with complex shapes by using mask and photolithography technology. However, with the rapid development of MEMS technolog...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/584C04B35/622
Inventor 李敬锋
Owner TSINGHUA UNIV
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