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Process for preparing layered silicon nitride ceramic with high strength and high toughness by utilizing component gradient design

A technology of silicon nitride ceramics and high toughness, applied in the direction of ceramic layered products, layered products, chemical instruments and methods, etc., can solve the limited application range, the brittle defects of silicon nitride ceramics have not been completely improved, compressive stress The effect is not obvious, etc.

Inactive Publication Date: 2014-08-20
SHANDONG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the brittle defects of silicon nitride ceramics have not been completely improved, which greatly limits its practical application range.
Because on the one hand, this design based on interfacial lamination stress needs to adjust the thermal expansion coefficients of the interfaces of each layer. If the difference between the thermal expansion coefficients of the layers on both sides of the interface is too large, it will easily cause interface peeling. If the difference is too small, the effect of compressive stress will not be obvious. The toughening effect is not ideal

Method used

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  • Process for preparing layered silicon nitride ceramic with high strength and high toughness by utilizing component gradient design

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] Step 1: the commercially available α-Si 3 N 4 , α-Al 2 o 3 , Y 2 o 3 According to the proportions in Table 3, use absolute ethanol as the dispersion medium, silicon nitride balls with a diameter of 2-3mm as the grinding medium, and ball mill in a nylon tank to control the particle size of the material to D50=0.2μm;

[0013] Table 3 Ingredients List (%)

[0014] Numbering α-Si 3 N 4 α-Al 2 o 3 Y 2 o 3 0# 85 8 7 1# 87 7 6 2# 90 6 4

[0015] Step 2: Add 5wt% polyvinyl alcohol (PVA) solution with a concentration of 3wt% to the above three mixed materials as a temporary binder. Follow the instructions figure 1 Add the materials corresponding to various numbers in the charging sequence, and press it into a block with an isostatic press at 100MPa, and the thickness of each layer after pressing should be controlled to about 2mm;

[0016] Step 3: Put the pressed sample into the pressure sintering furnace for pressure sin...

Embodiment 2

[0018] Step 1: the commercially available α-Si 3 N 4 , α-Al 2 o 3 , Y 2 o 3 According to the proportions in Table 4, use absolute ethanol as the dispersion medium, silicon nitride balls with a diameter of 2-3 mm as the grinding medium, and ball mill in a nylon tank to control the particle size of the material to about D50=0.2 μm;

[0019] Table 4 Ingredients list (%)

[0020] Numbering α-Si 3 N 4 α-Al 2 o 3 Y 2 o 3 0# 82 10 8 1# 85 8 7 2# 89 6 5

[0021] Step 2: Add 6wt% polyvinyl alcohol (PVA) solution with a concentration of 3wt% to the above three mixed materials as a temporary binder. Follow the instructions figure 1 Add the materials corresponding to various numbers in the charging sequence, and press it into a block with an isostatic press at 100MPa, and the thickness of each layer after pressing should be controlled to about 2mm;

[0022] Step 3: Put the pressed sample into the pressure sintering furnace for pre...

Embodiment 3

[0024] Step 1: the commercially available α-Si 3 N 4 , α-Al 2 o 3 , Y 2 o 3 According to the proportions in Table 5, use absolute ethanol as the dispersion medium, silicon nitride balls with a diameter of 2-3 mm as the grinding medium, and ball mill in a nylon tank to control the particle size of the material to about D50=0.2 μm;

[0025] Table 5 Ingredients list (%)

[0026] Numbering α-Si 3 N 4 α-Al 2 o 3 Y 2 o 3 0# 84 9 7 1# 88 7 5 2# 92 4 4

[0027] Step 2: Add 7wt% polyvinyl alcohol (PVA) solution with a concentration of 3wt% to the above three mixed materials as a temporary binder. Follow the directions figure 1 Add the materials corresponding to various numbers in the charging sequence, and press it into a block with an isostatic press at 100MPa, and the thickness of each layer after pressing should be controlled to about 2mm;

[0028] Step 3: Put the pressed sample into the pressure sintering furnace for pressu...

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Abstract

The invention aims to provide a process for preparing layered silicon nitride ceramic with high strength and high toughness by utilizing component gradient design, which comprises the following steps: (1), selecting alpha-Al2O3 and Y2O3 as sintering aids; (2), burdening, respectively weighing commercially available alpha-Si3N4, alpha-Al2O3 and Y2O3 powder according to the proportion of a burden sheet, taking absolute ethyl alcohol as a dispersion medium and a silicon nitride ball with the diameter of 2-3 mm as a grinding medium, ball-milling and uniformly mixing in a nylon tank, and controlling the granularity of a mixed material at about D50=0.2 mu m; (3), forming, adding a 5-9 wt% of polyving akohol (PVA) solution with the concentration of 3 wt% as a temporary binder into the mixed powder, adding various materials with corresponding numbers according to the charging sequence in the picture 1, pressing into blocky structures by using an isostatic pressing machine below 100 MPa, and controlling the thickness of each layer after being pressed at about 2 mm; and (4), sintering.

Description

technical field [0001] The invention relates to a process for preparing high-strength and high-toughness layered silicon nitride ceramics by using composition gradient design, which belongs to the field of new materials. Background technique [0002] Silicon nitride ceramics have good mechanical properties at room temperature and high temperature, high strength, low density, corrosion resistance, strong thermal shock resistance, chemical corrosion resistance, and low thermal expansion coefficient. It is the most widely studied structural material in structural ceramics. It is the main candidate material for ceramic engines and other high-temperature structural parts, cutting tools, wear-resistant parts, etc. It has always been a research hotspot of structural ceramic materials. However, the brittle defects of silicon nitride ceramics have not been completely improved, which greatly limits its practical application range. How to improve the toughness of silicon nitride cer...

Claims

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Application Information

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IPC IPC(8): C04B35/14C04B35/622B32B18/00
Inventor 乐红志杨赞中
Owner SHANDONG UNIV OF TECH
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