JPS6363771A - Bonding method - Google Patents

Abstract

PURPOSE:To achieve firm bonding and to enable the bonding of adherends having greatly different coefficients of thermal expansion from each other, by applying an adhesive to adherends and bonding them through a network structure. CONSTITUTION:In a method of bonding adherends to each other by means of an adhesive, a network structure is interposed between said adherends. The term 'network structure' as used herein refers to nets and netting including those prepd. by knitting thread, yarn and wire, those obtd. by welding or bonding the knitted goods into lattice structures and those obtd. by perforating flat sheets. The material of the network structure can be chosen from among metal, ceramic, carbon, etc., according to the use thereof, when heat resistance is taken into consideration. However, metal is preferred from the viewpoint of easy handling. When the network structure 3 made of metal has such a structure that it has branched protrusions 4, the effect obtd. by the method of the invention is further remarkable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a method of bonding two objects to be bonded by applying an adhesive.

Particularly in the field of using inorganic adhesives that require heat resistance, it provides an extremely effective means for bonding objects with widely different coefficients of thermal expansion, such as bonding ceramics and metals. do.

(Prior Art) Heat-resistant inorganic adhesives are typical examples of adhesives used in areas where heat resistance is required.

Heat-resistant inorganic adhesives generally consist of a binder based on alkali metal silicate or phosphate, a hardening agent, and a filler. When the objects to be adhered are made of different materials or have significantly different coefficients of thermal expansion, this can be handled by changing their compositions.

However, when adhering two adherends with different linear expansion coefficients in a place where they are subject to a temperature history of 300° C. or more, the adhesion force is inevitably weak and peeling often occurs.

(Problem to be solved by the invention) For example, when bonding two objects with different coefficients of thermal expansion, conventional inorganic adhesives change the composition of the binder, curing agent, and filler of the adhesive. It is difficult to adhere completely with just one.

The present invention was made to solve the above-mentioned problems, and aims to improve the bonding method in cases where conventional adhesives are insufficient for bonding, for example due to large differences in the coefficient of thermal expansion of the objects to be bonded. do.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and its gist is that in a method of bonding objects by applying an adhesive, This is an adhesion method characterized by intervening a net-like material.

Here, the net-like material is generally referred to as a net or a net.
This includes things made by knitting thread or wire, things welded or glued together in a grid pattern, and things made by punching multiple holes in a flat plate. In other words, it includes all planar objects that have a plurality of holes that communicate with each other on both sides.

The material of the mesh may be selected depending on the purpose, such as metal, ceramic, carbon, etc. in consideration of heat resistance, but metal is recommended in terms of cost and ease of handling. Hereinafter, the structure of the present invention will be specifically explained using an example of a metal mesh.

A metal net-like material is placed between the amount of the material to be adhered to the shroud and an inorganic adhesive is filled into the space.

Structurally, metal nets have hole-like spaces in a flat plate and are continuous (e.g., have a lattice structure), i.e. woven, welded, plate. Preferably, the void ratio is 50 to 60% or more.

FIG. 1 is a sectional view showing the relationship between an adhesive and an object to be adhered with a net-like material interposed therebetween to explain the present invention.

As shown in FIG. 1, if the net-like material has a structure having branched protrusions, the effects of the present invention will be even more remarkable.

The material of the metal mesh is preferably one that is resistant to oxidation when used in the atmosphere and has good adhesion to the adhesive used. It goes without saying that it is preferable to use a material with an intermediate thermal expansion coefficient for the surrounding plate adhesive.

In general, stainless steel nets are often sufficient to achieve the purpose. The lower limit of the thickness of the metal mesh is 10μ or more, preferably 50μ or more, because if it is too small, it will be easily consumed by oxidation at high temperatures. The upper limit of the thickness may be less than or equal to the distance between objects A and B to be adhered.

(Function) Even if distortion or the like occurs in the adhesive layer for some reason, it will be absorbed by the intervening net-like material, and even if a crank occurs, it will not be expanded any further and the adhesive state will be maintained. The operation will be explained in more detail regarding an example at high temperature, which is a typical case to which the present invention is applied.

In the adhesive layer, the metal mesh absorbs the compressive force, tensile force, and shearing force caused by thermal stress that occurs at high temperatures of several hundred degrees Celsius or tens of hundreds of degrees Celsius, and also absorbs the minute portion of the crank without expanding it. It also plays a role in keeping it in place. Therefore, even if a crack occurs to some extent, the metal mesh acts as a medium to connect both sides of the crack.

On the other hand, inorganic adhesives use water as a solvent, so the temperature is 100°C.
After hardening and dehydration at ~300°C, it becomes porous. In addition, the binder also foams slightly and becomes porous. Locally, these spaces serve as escape areas, allowing the metal mesh to deform and absorb the strain.

In other words, the entire structure of the adhesive and the metal mesh behaves as if it were a flexible material, firmly bonding the volumes of the shroud adhesive having different coefficients of thermal expansion.

Another role of the metal net is generally the temperature above 100℃~
During curing at 300°C, closed air pores are likely to form due to evaporation of moisture, but the net-like material itself becomes a fine air passageway that leads to the outside air. This speeds up drying and curing and provides sufficient adhesive strength. As shown in Figure 1, if the net-like material has protrusions branching to A and B so as to uniformly occupy the space between the surrounding plate adhesives A and B, it will act as an anchor to the adhesive layer. , it is even more effective.

(Examples and Comparative Examples) The method of the present invention will be explained in more detail below using Examples and Comparative Examples, but the present invention is not limited thereto. Note that parts in Examples and Comparative Examples indicate parts by weight.

As an adhesive, 40 parts of water glass No. 3, zirconia (≠10
An inorganic adhesive consisting of 0F, average diameter 50 μ) 52 parts, alumina 6 parts, and water 2 parts was used as a mesh to be interposed between the objects to be bonded.
25, 5841 iron plate (50m x 50cm x 3
- Thickness) and a sintered alumina plate (50m x 50mm x 8mm thick) were glued together using 08 grade adhesive.

As a comparative example, objects to be bonded were bonded without intervening a wire mesh under the same pond conditions.

For both (Example and Comparative Example), the temperature was repeatedly raised and lowered by 600°C, and the situation was observed. Table 1 shows a comparison between the two.

Table 1 (Effects of the Invention) According to the present invention, when bonding objects with an adhesive, by interposing a mesh between the objects, the adhesion becomes strong, and even if the bonding is caused by thermal history etc. It is possible to maintain a stable adhesive state without peeling even if cracks occur in the parts, especially when adhering two-component adhesives with considerably different coefficients of thermal expansion by adhering with a metal 5 metal net etc. in between. It becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view centered on the adhesive portion for explaining the present invention in detail. 1. Adhesives A, B, 2. Adhesive, 3. Metal type net-like object.

Claims (1)

[Scope of Claims] 1. A bonding method for bonding objects to be bonded by applying an adhesive, characterized in that a net-like material is interposed between the objects to be bonded. 2. The method according to claim 1, wherein the net-like material is a metallic net-like material. 3. The method according to claim 1 or 2, wherein the net-like material has protrusions.