JPH03122079A - Metallizing composition for ceramics - Google Patents

Abstract

PURPOSE:To improve the stability by blending a specified wt.% of Nb, Cr, Zr, Ti, C, Si, an SiC compound, one or more selected from W, Ta, Re and Os and, as the remainder, Ni and irreversible impurities. CONSTITUTION:Fine particles with <=150 mesh of respective components for constituting the subject metallizing composition composed of 3.0-22.0 wt.% Nb, <=20.0 wt.% Cr, provided that (Nb+Cr) is 15.0-22.0 wt.%, 1.0-5.0 wt.% Zr, 1.0-3.0 wt.% Ti, 1.5-3.5 wt.% C, 1.5-3.5 wt.% Si, 0.5-18 wt.% SiC compound, <=22 wt.% one or two or more selected from W, Ta, Re and Os and, as the substantial remainder, Ni and irreversible impurities are mixed and blended and a vehicle such as an ethylcellulose-based one is added thereto as a binder, thus obtaining paste-form metallizing composition. By applying the resultant paste to the surface of a ceramics-formed material, drying, subsequently carrying out heat treatment at 1,200-1,300 deg.C in a nonoxidative atomosphere and welding a metallic layer, a metallized layer is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a novel composition for metallizing the surface of various ceramics such as nitrides and oxides;
The present invention relates to a metallization method using the same and a metallized product to which the method is applied.

Conventionally, in the case of alumina ceramics containing several percent or more of sio2 components, a powder paste containing MO, Mrl and frit components has been used, and
This is a method of metallizing the surface of ceramics by baking at a temperature range of 500°C. The MO-Mn method has been implemented. However, 818N4 + MulN,
A series of newly developed nitride and oxide ceramic sintered bodies with excellent strength such as sialon and partially stabilized zirconia, high purity alumina sintered bodies with purity of 99.0% or more, sapphire, etc. For this purpose, metallization technology with strong bonding strength had not yet been established. Therefore, the above-mentioned [0
There has been a demand for the development of a practical metallization method such as the -Mn method.

The present invention was made in view of this situation, and
The metallizing composition of the present invention has a Nb content of 3.0 to 22.0
wt%, Cr is 20.0 wt% or less, Nb and C
The total amount with r is 15.0 to 22.0% by weight.

Zr: 1.0 to 5.0% by weight, T1: i, o to a,
o weight %, C 1.5 to 3.5 weight %, Si 1.
5 to 3.5% by weight, and 0.5 to 13% of SiC compound.
0% by weight, W, Ta.

This is a metallizing composition characterized in that it contains 22% by weight or less of one or more of Re or O8, and the remainder substantially consists of Nl and inevitable impurities.

The ceramics targeted by the present invention include 5isN4
, AeN, Sialon r A120B or M
These are nitride and oxide ceramics such as gO.

Nb in the composition of the present invention forms a eutectic with Ni to lower the melting point. Also, the intermetallic compound N between the two
Depending on the crystal orientation, 1aNb can exhibit large plasticity even at room temperature, so it can impart plasticity to a metallized layer formed by melting or semi-melting, and it can reduce thermal expansion and contraction between the ceramic and metallized layer. Due to the difference, the residual stress that occurs can be alleviated and the bonding strength can be increased. Furthermore, although Nb is not the same as Zr, it is one of the active elements, and it easily reacts with ceramics to form silicides, nitrides, oxides, etc., which strengthens the bond between the metallized layer and ceramics, and in large amounts. It is an extremely effective element in maintaining wettability with the ceramic during the initial or semi-molten stage of melting and preventing the welding area from shrinking more than the paste application area.

Cr is an element that forms a solid solution with Ni over a wide range of components, and has the effect of lowering the melting point. Also, like Nb, it is an active element, so it improves the wettability of ceramics and reacts with them to form silicides.

It is easy to form nitrides and oxides and has the effect of strengthening the bonding force with ceramics. However, unlike Nb, it does not have the effect of increasing the plasticity of metallization, so if it is included in too large a quantity, the above-mentioned Or
Since compounds such as CR and CR carbide are hard and brittle, cracks are likely to occur in the metallized layer. In addition, Cr forms a dense Cr directly on the surface of the metallized layer in air at a high temperature of 800°C or higher.
It is an effective element in forming a rich oxide film, preventing oxidation, and improving corrosion resistance. Therefore, in the present invention, one or both of Nb and Qr is blended in an amount of 13.0 to 22.0% by weight so as not to react too much with the ceramic and to appropriately lower the melting point. For the reasons mentioned above, Zarani Nb is
Even a small amount absorbs and relaxes the residual stress and strain caused by the difference in thermal expansion and contraction between the metallized layer and the ceramic, making it
Since it has the effect of preventing the occurrence of microcracks in the metallized layer that often occur when only Nb is blended, Nb must be blended in the range of 3.0 to 22.
0% (hereinafter weight % is omitted) wer is 20.0% or less, Nb, :C! The total with r is 15.0 to 22.
The range is 0%.

Zr or Ti is a very active element, and N
b-? )C! Because it is more reactive with ceramics than r, internal o, oi ~ 0.0 from the ceramic surface
Silicides and nitrides of these elements are diffused to the extent of 50% at the interface between the ceramic and the metallized layer.

Since an oxide can be formed, the bonding strength between the ceramic and the metallized layer can be significantly improved. However, if it is contained in too large a quantity, it may form hard and brittle intermetallic compounds, raise the melting temperature of the metallized composition, reduce fluidity, and form fine voids in the metallized layer. Adversely affect.

Also, among these two elements, Zr and Ti, Zr can lower the melting point of Ni more effectively in small amounts, and Ti is an element with slightly lower activity than Zr, but Ti Approximately half of Zr is preferably distributed because it further lowers the melting point of the metallized composition and suppresses the decomposition of ceramic components such as silicon nitride or alumina at high temperatures. Since there is usually some residual 02 in the high temperature atmosphere during welding, Zr and Tl are likely to combine with this 02, and at around 0.5% the properties of the metallized layer tend to become unstable; Exceeding this level is not preferable because the oxides produced by combining with the residual O2 impair the fluidity and wettability of the molten components in the metallized layer, thereby preventing the formation of a dense metallized layer. For the above reasons, the range T1 of 1.0 to 5.0% for Zr is 1.
It is preferable to incorporate Ti in a range of 0 to 3.0%.

C, together with 81, is an element that lowers the melting temperature of the metallizing composition. However, with only C, the welding temperature is 120
It cannot be lowered to about 0°C and it is necessary to coexist with Bi. For example, 8iaN4 starts to decompose into Si and N at a temperature of about 1250°C unless it is placed in a nitrogen or inert Ar gas flow, and high-purity Al2O
Regarding No. 3 as well, if the temperature is not higher than 1200°C, the surface starts to be partially reduced unless there is an oxidizing atmosphere, so it is not preferable to perform the treatment at higher temperatures for metallization. Also, S
i is a very effective element for increasing the fluidity of the metallized composition in the molten state, but if it is contained in too large a quantity, it will form a large amount of hard and brittle silicides in the metallized layer, which will deteriorate the mechanical properties. It is not possible to lower the melting temperature by adding a large amount of Bi alone because this would deteriorate the alloy and cause cracks. For the above reasons, in the present invention,
C and 81 are blended together in a range of 1.5 to 3.5% and 1.5 to 3.5%, respectively.

Furthermore, in the present invention, the SiC compound can be blended in an arbitrary range of 13.0% or less, but the SiC compound has good wettability with the metallizing composition of the present invention, and a part of the SiC compound reacts and melts. It can be a stable source of C and Si, so it can be used in cases where C or Si is insufficient and difficult to melt due to temperature fluctuations or variations during metallization processing.
Alternatively, if C becomes CO2 gas and is depleted due to residual 02 in the atmosphere, and there is a shortage, Si and C can be eluted from this SiC compound to an amount that balances at the processing temperature, resulting in a stable product. I can do it. Also, S
iC originally has a small coefficient of thermal expansion ((5,5X10"/"C
) The remaining SiC in the metallized layer lowers the thermal expansion coefficient of the metallized layer, resulting in 5iaN4(B, 2X
10''/C), Sialon (8,2X10/'C)
.

It is effective because it approaches the value of the thermal expansion coefficient of A120g (6.5X 10"10) and can reduce residual stress and strain. If it is added in excess of 18%, SiC compounds and other metals remaining in the metallized layer will be removed. The amount of the hard and brittle compound of element 81 and C is too large, impairing the flexibility of the metallized layer and deteriorating it, so it should be 18% or less.Also, as a SiC compound, the diameter without dislocations is better than just powder particles. SiC whiskers, which have extremely excellent mechanical properties of about 0.01 μm or less and a tensile strength as high as 800 kg/ws2, can also be used as a suitable SiC component compound. For this reason, the content should be 0.5% or more, and the component range should be 18% or less.

W, Ta, 几e, and QS in the composition of the present invention are all elements with extremely high melting points, and even if the other component elements of the composition of the present invention melt at about 1200 to 1800 °C, they will completely melt. It can be used as a filling material component. All of these elements also have a coefficient of thermal expansion of 4.5.
A metal with a small value in the range of ~6.6X10''/''C, alone or in combination as a filler material component.
By blending within a range of 2.0% or less, the thermal expansion coefficient of the metallized layer can be adjusted or the heat resistance can be increased. However, if it is contained in an excessively large amount, the flexibility of the metallized layer will be impaired, so it is rather disadvantageous to mix it in an amount exceeding the above range.

When the metallizing composition of the present invention is to be welded to various ceramics, the alloy powder of the composition as described above is 150 meshes or less, preferably 325 meshes or less, and in order to form an even finer pattern by metallization, the alloy powder is 500 meshes or less. Alternatively, in order to impart appropriate fluidity and adhesion to the ceramic surface to the powder obtained by mixing some or all of them, a vehicle such as ethyl cellulose or acrylic is mixed as a binder to form a paste. It is applied to the specified surface of the ceramic using a coating technique such as screen printing, a brush, or a spatula, and after drying, it is coated with unevenness.
N2+ H2+ 120 in a non-oxidizing atmosphere such as vacuum
The metallized layer is melted or semi-molten by holding it in a temperature range of 0 to 1300° C. for 5 to 25 minutes to weld the metallized layer.

Si3N4+ sialon whose surface was metallized by the method of the present invention using the composition of the present invention described above.

hllN, partially stabilized zirconia, high purity i 209
Ceramic sintered bodies such as
4,co, Mug, MuPt, Pd, Rn,
Melting oxidation-resistant metals such as lu, electroless,
Brazing with silver solder, gold solder, nickel solder, palladium solder, copper solder, etc. is achieved by coating with a coating of about 0.001 to 0.00 otom by plating methods such as electrolysis, physical coating methods such as vapor deposition, and sputtering. During this process, it is possible to prevent active elements from being oxidized by O2 remaining in the atmosphere of the brazing furnace, forming oxides on the surface of the metallized layer, and deteriorating the flowability of the brazing material.

The ceramic products having the metallized surface of the present invention can be made of various practical metals and alloys, such as copper, Kovar,
For tungsten, molybdenum, silver, aluminum, and alloys of these metals, as well as hard metals and alloys with large thermal expansion coefficients, the above metals and alloys are used as an intermediate buffer material and are interposed between the ceramics and brazed. Therefore, it is also possible to braze Inconel, heat-resistant steel, Hastelloy, carbon steel, etc.

According to the present invention, Si3N4 has a strong bonding force, which has been difficult to manufacture in the past, and has a metallized surface that can be processed at a moderate temperature range of 1200 to 1800°C. We are now able to manufacture metallized ceramic sintered products such as Sialon, klN, high purity AA'20g, and MgO. Therefore, the most rational design from a characteristic or economic point of view is possible, and the above ceramics can be used for various purposes such as automobile engine parts, wear-resistant parts,
The present invention can be effectively applied to various uses such as heat sinks, electronic circuit boards, high-temperature jigs, cutlery, tools, and vacuum circuit breakers.

Next, the present invention will be explained in detail.

Examples Various metallizing compositions of the present invention as shown in Table 1 are mixed and blended with fine powders of each component of 82.5 mesh or less and an 8iC compound, and an ethyl cellulose vehicle is mixed in to form a paste. And so.

Next, a pressureless sintered s i with a diameter of 12 and a height of 5+++s
2N.

Apply this thinly and homogeneously on the surface of the board, and after drying, it will be 0.04 ~
The thickness was set to 0.05118. Further 1200-128
Hold at 0°C for 10 minutes to weld the metal layer to a thickness of 0.
A metallized layer of 02-o, o ass was formed.

After that, Ni plating was applied to the fin to a thickness of about 0.005, and the diameter of the Kovar alloy was 3.8w and the length was 10m1II11.
The end faces of the individual pieces were brazed with eutectic silver solder at 850°C for several minutes in a hydrogen stream, and after cooling in the furnace, a shear test was performed and the values listed in the table were obtained. .

The thermal expansion coefficient of silicon nitride and Kovar alloy in the temperature range of about 25 to 500°C is 3.2 x 10 /'C
.

6.0 x 10'', which is nearly double the difference, and shows a strong value even when taking into consideration the residual strain that occurs during brazing. If applied, it can reduce brazing distortion and improve the bonding strength, so it can be used as an industrial ceramic-metal bonded part, such as wear-resistant tile brazed panels for large blower blades, and as automobile engine parts. It can be used on a large scale.

Part 1 table

Claims (1)

[Claims] 3.0 to 22.0 wt% Nb, 20.0 wt% Cr
The total amount of Nb and Cr is 15.0 to 22.0% by weight, Zr is 1.0 to 5.0% by weight, and Ti is 1.0 to 3% by weight.
．． 0% by weight, C 1.5-3.5% by weight, Si 1.5% by weight
~3.5% by weight, 0.5-18% by weight of SiC compound,
One or more of W, Ta, Re or Os at 22
1. A metallized ceramic composition characterized in that it contains not more than % by weight and the remainder substantially consists of Ni and unavoidable impurities.