JPS59190270A - Silicon nitride sintered body and manufacture - 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 (a) Technical Field The present invention relates to a silicon nitride sintered body that has a high density and high hardness, and a method for producing the same.

(b) Technical background Silicon nitride sintered bodies have traditionally attracted attention as one of the engineering ceramics used for high-temperature structural members, but silicon nitride (S'3N4) alone is difficult to sinter. , low melting point compound 71i - can be used as a sintering aid for sintering.
, oxides of Nh elements, beryllium (J3e), zirconium (Lr, L) or two or more on lanthanide-based fabrics such as yttrium (Y), lanthanum (La), and cerium (Ce). Flow power 1) Otsu method is known.

In addition to this, a method has also been proposed in which nitrides and oxides of the above-mentioned elements are used as the sintering aid 11.

ing.

However, in any of the above cases, it is not only difficult to simultaneously achieve high flexural strength and high hardness, but also to obtain a dense sintered lV4: U-hot press, etc. Problems such as the need for pressure sintering have been pointed out.

t rc The use of zirconium oxide (Z r O
, 1976), high-purity monoclinic ZrO, which has been recognized to be effective in improving sinterability, is used as the raw material for ZrO2.

Although the characteristic values are not /J<, judging from the raw material purity and the crystal form of ZrO2 in the obtained sintered body, it is predicted that the characteristics will deteriorate due to +r+2a of Zr'02. The deterioration was confirmed by experiments conducted by the present inventors.

e→ Disclosure of the Invention In view of the above points, the present inventors have conducted various studies on sintering aids for Si 3N, and have found that ZrO2, which has a cubic crystal shape, can be used as a sintering aid in S + 3N4 sintering. Stabilization of ZrO2'? l: Use, then A, Y,
The present invention was based on the discovery that a high-strength silicon nitride sintered body with excellent sinterability can be obtained by using oxides of lanthanide rare earth elements (i- as a sintering aid). .

That is, this invention contains S+3N4 as a main component, and an amount of 1 to 25% by volume in a cubic Zr0zk-generating sintered body stabilized with at least one of CaO, Δigo, and Y2O3. , Al2O3, Y2O3, and one or more oxides of lanthanide rare earth elements. L
A silicon nitride sintered body containing the above elements in an amount of 1 to 15% by weight, and the above-mentioned mixed powder is sintered in an atmosphere of Kanya Soganu. This provides a method for producing a silicon nitride sintered body in which most of the Si3N4 is β+[] and the average grain size is 2 μm or less.

In this invention, if the amount of cubic 1r02 in the produced sintered body is less than 1% by volume, the effect of adding ZrO2 will be small, and if it exceeds 25% by volume, the strength of the sintered body will decrease significantly. The individual weight range is 1 to 25%.

Stabilizing ZrO□ in the cubic form S < CaO1M, g
The same effect can be achieved by using either O or Y2O3, and the influence (ri) of the type of stabilizing substance is small.

he2o,,Y,0. as a sintering aid. Oxides of lanthanide rare earth elements are not necessarily limited to these, and nitrides of these elements can also have the same effect, but due to ease of handling, the above 1'1 The monster is heavy.

And these two-year-olds
A similar effect can be obtained on lj l;, 1, but the force t is defined as the content of A (1', -4°Y, La, etc.) in the C plain sintered body (((day?) If the concentration is less than 2 FIJ (%), it will be difficult to densify the sintered body, and
In case of lech, the decrease of yl in the sintered body is markedly 1-7, so it is preferable to contain 1 to 15% of heavy mushroom.

As described in detail above, the invention of (2008) is a stabilized Zr U 2 of cubic crystal, II et al.
It is.

Hereinafter, as an example of this invention, i'1 night 11 and quotient 1
I will clarify.

Example 1 The sintered body shown in Table 1 was obtained. ζU Vko, /7
-8i3N4 powder, city th MgO stabilization, zr 02
Powder, Al2O3 powder, Y2O3 powder, L a 203
After mixing powder and Ce 02 powder, 1t/cm h
It was static pressure molded using two tools.

Furthermore, from this molded body, 6MM x 6Mm x 40
The molded body cut into MMO size was rim-solidified in nitrogen gas at 1750° C. and 2 atm for 2 hours.

Regarding the obtained sintered body, density, weight loss rate, (+iJj degrees,
Even though the t'iu rupture force was determined to be 41 (1), the results shown in the table H<1 were obtained, confirming the utility of this invention.

In addition, in this example, the formulation for producing a sintered body, tri
An example of the number in Table 1 is shown below.
g O stabilized, Z r' 02 powder 5.5'fj
%, k1203 powder 9.5 weight (11%, remainder α-8i
3N4 powder, which produced 11 sintered bodies having the composition shown in Table 1.

・Those with numbers marked * in Table 151 are compositions outside the scope of the claims of this invention, and are comparative examples to j6]2.13 Il;.

Examples For mixtures of numbers 2, 8, 9, 10, and 12 among the numbers shown in Table 1, 200 Icq at 1750°C in 1 trade pressure of nitrogen.
A sintered body was obtained by hot pressing for 1 hour under a pressure of /cl.

The obtained sintered body was subjected to the same procedure as in Example I. All the results shown in Table 2 were obtained. When sintering was carried out under the conditions of Example 1 using ZrO2 powder, which was monoclinic and had an average secondary particle size of 5μ, hair cracks occurred in the obtained sintered body, and the sintered body was Jl jti. I found out that I can't get it.

Claims (4)

[Claims] (1) Silicon nitride is the main component, and cubic zirconium oxide is generated in the sintered body at 1 to 25% by volume, as well as one or more of aluminum, yttrium, and ranknidic rare earth elements. A silicon nitride sintered body, characterized in that the content is 1 to 15% by weight in the sintered body. (2) Cubic zirconium oxide is calcium oxide,
The silicon nitride sintered body according to item 1 of the scope of the specification R'1, characterized in that the sintered body is stabilized by at least one of magnesium oxide and inotrium oxide. (3) Cubic zirconium oxide powder in an amount such that the content in the generated sintered body is 1 to 25% by volume, and one or two types of oxide powder of aluminum oxide, yttrium oxide, and ranknidic rare earth elements. A mixed powder consisting of 1 to 15% by weight of the above elements and the remainder being silicon nitride powder is sintered in a nitrogen gas atmosphere, and most of the silicon nitride is β-tag. 1 (binary system) of a silicon nitride sintered body characterized by obtaining a sintered body with an average grain size of 2μ or less. (4) Production of the silicon nitride sintered body according to claim 3, wherein the cubic zirconium oxide is stabilized with at least one of calcium oxide, magnesium oxide, and yttrium oxide. Drink law.