JPS59199582A - Method of sintering sialon base sintering material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention The present invention provides a sialon sintered material that does not form a surface altered layer during sintering, that is, can be put to practical use in the sintered state, and a sialon-based sintered material containing sialon as a main component. The present invention relates to a method for sintering materials (hereinafter collectively referred to as sialon sintered materials).

In recent years, various new ceramics, especially silicon nitride (Si3N), have been used as structural materials for turbine plates and other materials.
4) or a compound in which a part of Sl in Si3N4 having a β-type crystal structure is replaced with A or e, and a part of N is replaced with 0, that is, a composition formula.

5i6-2. I! VzO2N8-z (but 0 (z
= 4.3), and then α
A part of Sl in the crystal lattice of Si3N4 having a type crystal structure is replaced with 8β and a part of N is replaced with '6o, and Li, Na, Ca, lvl and rare earth elements with small atomic radius are substituted at interstitial positions. 1 type and 2 or more types (
In the following compositional formula, J・A) is a solid solution in interstitial form, that is, the compositional formula Mx (Si, A) + 2 (0, N) + 6 (however, O
<x≦2) Sintered material composed of α-SiAlON, and Si3N4 containing these components as main components
Base sintered material 441 and Sialon-based sintered material are attracting attention.

However, when producing these sintered materials, especially sialon-based sintered materials, (a) If the compacted compact is directly sintered in a state embedded in Si3N4 powder or sialon powder, the compacted powder If the surface part of the body reacts with the sintering atmosphere and the embedding powder to form a surface-altered layer, and if there are holes or depressions on the surface of the compacted compact, the embedding powder may be present in these areas. These powders are not only hard to remove, but also become the cause of deformation because they are strongly trapped during shrinkage during sintering.

(b) When the compacted compact is sintered in a graphite crucible, a reaction occurs between the surface of the compact and the sintering atmosphere, resulting in a surface-altered layer. Although this is not as remarkable in the case of a graphite crucible, it occurs similarly when sintering in a Si3N4 base sintering yield I-1 crucible.

In the past, problems such as these occurred, and in the case of sialon-based sintered materials, after sintering, it was necessary to completely remove the surface-altered layer and powder-incorporated layer formed on the surface.
This surface-altered layer requires effort and time to remove, in addition to the fact that the sialon-based sintered material is difficult to grind.

Therefore, from the above-mentioned viewpoint, the present inventors conducted research on the sintering mode of the sialon-based sintered material in order to obtain a sialon-based sintered material free from the formation of altered layers or powder-incorporated layers on the surface portion. As the embodiment is shown in a schematic longitudinal cross-sectional view in FIG. 1, a compacted powder body 1 is formed into a Zialon-based sintered powder having the same or similar composition as the compacted compact. 1 or a container 2 made of Si3N4-based sintered material (including Si3-toothed sintered material) whose inner surface is coated with a mixed powder having the same or similar composition to that of the compacted compact.
4 powder or a mixed powder containing S'1-3N4 powder as the main component, and then charged in the container 2.
All graphite melt 4 contains Si3N4 powder 5 or Si
When the graphite melt in this state is charged in a mixed powder 5 whose main component is 3N4 powder and sintered in a nitrogen-containing atmosphere, the atmosphere surrounding the compacted compact during sintering changes. , the volatile components of the compacted compact itself, such as SiO gas generated by the decomposition of a part of Si3N4, are similar, and this decomposed gas atmosphere blocks the outside air, and as a result, the compacted compact Since it is presumed that there will be no formation of a surface-altered layer on the body due to reaction with the external atmosphere, it is possible to obtain a sialon-based sintered material with good surface properties. Since the green compact is not embedded in the powder, there is no formation of a powder-incorporated layer (↓).

This invention was made based on the above findings, and will be specifically explained below using Examples.

As the example raw material powder, average particle size: 0.871+11 S
j, 3 N4 powder (α phase content 90% by weight), 0
6μm α-AA203 powder, same 10μ? ? 7 Y2O
3 powders, all 15pm MN powder, Ti0N
(TiC/TiN=2/85 weight ratio) powder and carbon blank powder are all prepared, these raw powders are blended into the composition shown in Table 1, and paraffin as a binder is added to the blended powder. Add 4% by weight to 3
After wet mixing in a ball mill between N and drying, the resulting mixed powder was press-molded and then molded in a vacuum with an accuracy of 8.
Molded green compacts a to 0 were produced by holding at 00° C. for 1 hour to volatilize paraffin as a binder.

Next, using these compacted powder compacts a, -Off, the following conditions are performed: Inside the manufactured container, Si3N4
Place the powder and place the whole container in the graphite crucible.
immersed in i3N4 powder and charged (hereinafter referred to as \A Tsujiaki method 1); A molded compact was placed in a material preparation container with 813 N4 powder spread thereon, and the entire gold graphite melt was immersed in Si3N4 powder (hereinafter referred to as the method of the present invention). 2), (:3)
8 13-Sintering 42 In a separate container, the molded green compact C was coated with a mixed powder having the same composition as the compacted powder body C.
k Sj, 3N4 powder is laid out on an anvil, and the entire container is immersed in Sj, 3N4 powder in a graphite crucible and charged (
(hereinafter referred to as the present invention method 3), (4) Sj, 3N4 whose inner surface was coated with a mixed powder having the same composition as the compacted compact a
A molded green compact d f Si3N4 powder is spread and placed in a container made separately for the sintered material, and the entire container is placed in a graphite crucible with Si3N4 powder.
3N4 powder and charged (hereinafter referred to as the method 4 of the present invention). (5) The inner surface was coated with a mixed powder having the same composition as the compacted compact C and placed in a container made of Puhi 513N4 sintered powder. ,
Molded compact e'f, (Si3N4 powder is spread and arranged, and the entire container is placed in a graphite melting ring S:L3N,
+ Charging by immersing it in powder (hereinafter referred to as the method 5 of the present invention)
, (6) Molded green compact A15 graphite melt (・Si3N in 1
4 Burying and charging in powder (hereinafter referred to as comparative method 1),
(7) Complete charging of compacted powder l) under the same conditions as method 1 of the present invention except that the container was made of graphite (hereinafter referred to as 1.-1 Comparative method 2)
(8) Charge the compacted compact C under the same conditions as method 1 of the present invention, except that the container is made of graphite (hereinafter referred to as comparative method 3), (9) The container is made of graphite Other than that, the molded green compact J was charged under the same conditions as the method 4 of the present invention.
(referred to as Comparative Method 4), (10) The compacted compact 0 was placed in a 5iaN4 sintered material container with Si3N4 powder spread thereon, and the entire container was immersed in the Si3N4 powder in a graphite crucible and charged ( (hereinafter referred to as Comparative Method 5), in any of the above (1) to (10), in a nitrogen atmosphere of 1 atm, at a temperature of 700°C (by sintering under the condition of holding for 2 hours). Invention/1: 1 to 5 and Comparative Methods 1 to 5 were carried out, and the cross section of the resulting sialon-based sintered material was polished to determine the average thickness of the surface altered layer. The results are shown in Table 2.

From the results shown in Table 2, it can be seen that in the sintered 1-container-based sintered A-1 (C) obtained by methods 1 to 5 of the present invention, the surface deterioration layer was not tolerated at all. In Comparative Methods 1 to 5 (.C), the formation of a surface-altered layer was observed in all of them.

As described above, according to the method of the present invention, there is no formation of a surface-altered layer or a powder-incorporated layer on the Zialon-based sintered second material after sintering, and therefore, without grinding, etc.
When put to practical use in the sintered state, it brings about practical effects such as the ability to burnish.

[Brief explanation of drawings]

FIG. 1 is a schematic vertical sectional view showing an embodiment of the present invention. In the drawings: 1. Molded compact; 2. Container; 3. Underlay; 4. Graphite crucible; 5. Powder for burial. Applicant Mitsubishi Metals Co., Ltd. Agent Tomi 1) Kazuo and 1 other person

Claims (1)

[Scope of Claims] When sintering the sialon-based sintered material, the compacted powder is not crushed, and the container or inner surface made of the sialon-based sintered material has the same or similar composition as the compacted powder. In a container made of a silicon nitride-based sintered material coated with a mixed powder having the same or similar composition to that of the above-mentioned compacted compact, silicon nitride powder or a mixed powder mainly composed of silicon nitride powder is spread on a T. Then, the container is placed in a graphite crucible in a state where it is buried in silicon nitride powder or a mixed powder mainly composed of silicon nitride powder, and the graphite crucible in this state is placed in a nitrogen-containing atmosphere. A sintering method for sialon-based sintered materials, which is characterized by sintering in a medium.