JPH03226585A - Production of laminated structure by coating - Google Patents

Abstract

PURPOSE:To produce a fine and uniform laminated material of intermetallic compound with certainty by successively applying plural pasty compositions prepared by mixing dissimilar fine powders, respectively, to a substrate and solidifying the resulting coating layers. CONSTITUTION:Plural pasty compositions 3 respectively prepared by uniformly mixing dissimilar fine powders by regulating blending ratio are successively applied to a substrate 2 by using a screen 1. The resulting coating layers are solidified, and the desired distribution of composition is attained in the direction of coating. The thicknesses of the coating layers are regulated to values between micron order and several tens microns, respectively. The substrate 2 is recoated, in succession, with respective pasty compositions in which blending ratios of dissimilar fine powders are changed by stages in the direction of thickness. At the time of solidifying the coating layers, the reaction of diffusion combination is performed by means of heating. By this method, the laminated material in which the distribution of composition is intentionally provided can be produced.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for manufacturing composite structures by coating.

More specifically, the present invention is applicable to composite materials that require control of composition distribution on the order of 0 microns, ■ new materials that have a sufficiently controlled micro-uniform structure that cannot be achieved with cast lumber, and ■ intermetallic compound materials. The present invention relates to a method for manufacturing composite structures that can be used in the field of new materials such as.

It is thought that the manufacturing method according to the present invention can be applied to, for example, the following material fields. Therefore, the composite structure manufactured by the method according to the present invention has significance as an improved material for those materials.

(1) Gradient composite material: A composite material whose composition distribution is intentionally changed by 10 degrees in a certain direction.

(2) Materials with a controlled uniform microstructure that cannot be achieved with 'R materials: ■ Uniform finely mixed materials of components that do not melt together ■ Materials with uniform microstructures of intermetallic compounds (conventional technology) Conventional techniques for composite structures One such technology is gradient composite material manufacturing technology. The conventional technology that has been completed as a technology for producing graded composite materials can of course be applied as a technology for producing materials with a uniform microstructure, so in this specification, this technology for producing graded composite materials will be mainly described as the prior art. .

That is, when high precision formability, toughness, and heat resistance are required at the same time, it is physically desirable to coat the processed metal surface with a ceramic layer. However, since metals and ceramics generally have significantly different coefficients of thermal expansion, there is a fundamental contradiction in that they tend to separate from each other when used in a high-temperature atmosphere. For this reason, precise control of composition distribution is required in metals and ceramics, especially in metals and heat-resistant ceramic materials.

In this way, the manufacturing method for functionally graded composite materials suppresses cracks caused by thermal stress caused by the difference in thermal expansion between metal and ceramic when metal and ceramic are directly bonded together and used as a heat-resistant material. According to this technology, the difference in thermal expansion is alleviated by sandwiching a composite material in which the mixing ratio of metal powder and ceramic powder is continuously changed in the thickness direction between metal and ceramic. The aim is to prevent thermal cracking caused by thermal stress that occurs during heating and cooling. In this way, a composite material can be obtained that takes advantage of the heat resistance of ceramics and the precision workability of metals.

Currently known methods for manufacturing +11 functional composite materials having such characteristics include the following methods.

■Physical Vapor Deposition (PVD) This is a surface coating that uses physical vapor deposition methods such as spackle method and ion blating method. During surface coating, a reactive gas is passed through the atmosphere, and the gas composition is changed over time to sequentially form thin layers with different compositions in the deposition direction.

For example, in forming a Ti-TiC film, Ti is not deposited by the ion-blating method, but by changing the flow rate of CH4 gas stepwise over time, Ti-TiC is deposited in the deposition direction.
The iC0 ratio can be changed in a gradient manner.

■Chemical vapor deposition method (CV D) This is a surface coating method that uses a gas phase chemical reaction method.

During surface coating, different reactive gases are further passed through, and while the gas composition is changed over time, thin layers having different texture compositions in the browning direction are continuously formed. For example, 5i-5i
In the second case of C film formation, Si was oxidized by a gas phase reaction method, and the 5iC-C ratio was changed in a gradient direction in the evaporation direction by changing the flow rate of CI (4 gases stepwise over time). can be done.

The reaction formula in this case is shown below.

5iCQa+CH4-5iC(s)+C(s)+4HC
Q(g)■ (Physical vapor deposition + chemical vapor deposition) fusion method This is a method in which physical vapor deposition and chemical vapor deposition are performed simultaneously to form a film while continuously generating a compound. At this time, the composition ratio can be changed in a gradient manner by changing the gas pressure.

For example, sputtering of Sn and plasma CVD using 5iHn gas are performed simultaneously to form films of Sn and Si. The composition ratio of Sn and Si is determined by the plasma CVD gas (Si
The pressure is changed by changing the pressure of H4, Ar). Again, by changing the pressure stepwise over time, the ratio of 5n-Si is changed in a gradient manner in the deposition direction.

■ Doctor blade method A functionally graded material is created by stacking thick film plates with different compositions as plate-shaped thick films using the doctor blade method using a mixed powder that has been made into a slurry in advance.

■ Thermal Spraying Method This is a composite method using so-called plasma spraying, which is used in meat tr'18 spraying, etc., and mixes different types of particles while changing the desired composition ratio and supplies them into the plasma by powder transport. , to form a film. Methods for supplying different types of particles by powder transportation include an independent method for supplying different types of particles from different nozzles, and a simultaneous method for supplying different types of particles from the same nozzle.

(2) Particle injection method Different types of particles are mixed while changing the composition ratio as desired, and then supplied in the form of a mixed powder through a nozzle on a substrate, and then sintered to form a film.

(Problems to be Solved by the Invention) However, in the manufacturing method of such a composite structure, it is currently difficult to realize the ideal compositional distribution of two or more components derived from theory and design on an industrial scale. There is no manufacturing method available.

The above method has the following technical and economical problems.

■Physical Vapor Deposition (PVD) In general, it is difficult to obtain a product with sufficient thickness because the deposition rate is slow. Usually, the thickness is less than the micron order, and it takes a considerable amount of time to obtain a thickness that is industrially meaningful.

Furthermore, since simultaneous reaction with gas is used for composition control, the combinations of target compositions are limited.

■Chemical Vapor Deposition (CVD) In general, 1 Sodium Soda is faster than the physical thinning method, but it is still often difficult to obtain a sufficient thickness for industrial use. Since gas reactions are used for composition control, the combinations of target compositions are limited.

As described above, physical deposition and chemical vapor deposition are close to ideal from the viewpoint of compositional gradient control, but there are limits to productivity and composition combinations due to fundamental defects arising from the actual manufacturing process.

Therefore, industrial application is difficult except in special cases.

■(Physical vapor deposition↑Chemical vapor deposition) fusion method This method is a combination of the above-mentioned physical vapor deposition method and chemical vapor deposition method, so it has the problems of both methods.

■ Doctor Blade Method The thickness of thin plates produced by the current doctor blade method is 50uI11 or more due to handling constraints.

Therefore, the gradient distribution of the composition has to be roughly step-like, which often defeats the original purpose.

Furthermore, producing thin plates one after another is extremely inefficient.

As described above, the doctor blade method cannot be said to be practically sufficient in terms of accuracy and productivity of gradient composition distribution.

■ Thermal spraying method Although this method has few problems in terms of mass production, there are problems with accuracy due to the method when it comes to composition control.

In other words, with the current plasma spraying method, there is a limit to the thickness of the layer, which is at most a few layers, and because the local reactions of melting and solidification are repeated, it is currently difficult to obtain a flat interface, and the composition in the thickness direction is limited. There is a problem with controllability.

■ Particle injection method This method also has few problems in terms of mass production, but simply spraying the mixed powder from a nozzle onto the substrate and laminating it raises the problem of thickness control and the basic problem of classification, which is essential for supplying a mixture of different particles. is unavoidable in principle, and there are problems with accuracy due to the method from the viewpoint of composition control.

The purpose of the present invention is to provide a composition distribution with functionally acceptable accuracy relative to the ideal composition distribution of two or more components derived from theoretical and design reasons, and to achieve an industrially practical composition distribution. The aim is to develop a manufacturing method for composite structures with high productivity.

(Means for Solving the Problems) In other words, the first object of the present invention is to solve these problems by providing an improved and devised method for manufacturing a composite structure so that a thinner composite layer can be formed at the same time. It is to provide.

A second object of the present invention is to provide a method for manufacturing a composite structure that achieves a good balance between mass productivity and composition control accuracy.

In order to achieve this object, various studies have been carried out, and the following findings have been obtained, and the present invention has been completed based on these findings.

In other words, with a coating method such as screen printing, it is easy to control the film thickness, and especially when the thickness of each coating layer is on the order of microns to several tens of microns or less, it is also easy to control the composition. It can be done even more easily. Furthermore, since the coating method can be carried out using a simple device and can cover a wide area of the substrate at once, the productivity is significantly improved.

Here, the gist of the present invention is to sequentially apply a plurality of paste-like compositions in which dissimilar fine powders are uniformly mixed by adjusting the blending ratio of each composition onto a substrate, and to solidify the obtained coating layer. This is a method of manufacturing a composite structure by coating, which is characterized by realizing a desired composition distribution in the coating direction.

According to a preferred embodiment of the present invention, the thickness of each coating layer is on the order of microns or more and less than several tens of microns, and the paste-like composition further includes a composition in which the blending ratio of different types of fine powders is changed stepwise in the thickness direction. The paste composition may be coated one after another, or each paste composition having a constant blending ratio of different fine powders may be coated one after another.

Further, as a means for solidifying the coating layer, drying and/or
Alternatively, heating and/or sintering may be performed, in which case solidification may be performed after each application.

According to another aspect of the present invention, when solidifying the coating layer, a diffusion compounding reaction may be performed by heating, and after solidifying, the obtained thick film fired body is further rolled for densification. Pressure may be applied by HIP or the like.

In the present invention, the coating method is not particularly limited, but it is preferable to apply the paste composition using a printing method using a screen.

Thus, according to the present invention, the following configuration is adopted.

■ Use pre-prepared fine powder to ensure mass production.

■ To ensure the precision of mixing different types of powders, a viscous liquid is used as a dispersant and binder to form a paste-like mixed powder.

■ In order to obtain a uniform microstructure material or a functionally graded material with an accurate composition distribution, the above paste-like mixed composition with a uniform composition with a fixed blending ratio or with a stepwise change in composition is mixed in micron order to several tens of microns. Apply in the following thicknesses sequentially.

(2) In order to sequentially apply the coating to a thickness of the micron order or more and several tens of microns or less, for example, a printing method using a screen is used.

(2) After solidification, the obtained thick film sintered body may be pressurized by rolling or HIP or sintered to further densify it.

(Operation) Next, the configuration and operation of the present invention will be explained with reference to the attached drawings.

That is, according to the present invention, a paste composition in which different types of fine powders are mixed uniformly by adjusting the blending ratio is applied, but by repeating the application and solidification multiple times, the resulting composite structure can be Control composition distribution.

Organic vehicles used to form a paste include ethylcellulose, hydroxyethylcellulose, nitrocellulose, polyvinyl alcohol, paraffin, polyester, polyvinyl chloride, P? A base material such as IMA acrylic dissolved in terpineol, aromatic solvents, various glycols, acetic esters, etc. is used.
In addition, oleelamine, N-alkyl-1,3-diaminopropanediolate, etc. may be used as an activator (dispersant). There is no particular restriction on the amount of powder blended, but 3 to 1
About 5% (weight) is sufficient.

Powder compositions targeted by the present invention include, but are not particularly limited to, Ti/TiC compositions, Si/SiC compositions, SnO
/SiO□ compositions and hydroxyl abatai)/Ti alloy compositions.

By repeating coating and solidifying multiple times and minimizing the coating layer thickness each time, we can achieve the ideal composition distribution of two or more components based on theoretical and design reasons. , it is possible to provide functionally acceptable compositional distribution accuracy, and for this purpose, it is better to apply as many times as possible, while the blending ratio in each coating layer may be exactly the same in some cases, or it may be extremely small in some cases. Change the amount one by one. In this way, in order to approximate the continuous composition distribution to an aggregate of uniformly mixed layers with a functionally acceptable microthickness, by sequentially stacking uniformly mixed layers with a microscopic thickness, the ideal compositional distribution can be approximated. be.

From a practical standpoint, such a coating operation is preferably carried out by printing or by a screen printing method in which the printing and solidifying processes are repeated multiple times.

No. 111m is a schematic explanatory diagram illustrating the operation when performing the coating method according to the present invention by a screen printing method.

Then, a thick film is formed by printing the paste 3 on the substrate 2. To create multiple layers, the same operation can be repeated after printing and drying.

After applying a predetermined number of coats, it is sintered and fired.

According to a preferred embodiment of the present invention, a paste composition in which the blending ratio of one or more metal powders and ceramics is changed in stages is coated over and over again. Compounds are generally limited to metal powders and ceramics, but the specific materials that require such precise composition distribution are mainly composite materials of metals and ceramics.

The coating layer obtained in this way is "solidified" each time or after the coating of the entire layer is completed.
This includes the steps of drying, sintering, and melting the particle layer, and in short, refers to an operation that realizes the integration of the particle layers constituting the coating layer. Specifically, (1) unification of the powder layer by diffusion phenomenon (so-called diffusion sintering), (2) unification of the powder layer by partial particle surface melting (liquid phase sintering), (3) Integration of powder layers by melting only one type of constituent particles (e.g. ceramic, metal particles in a metal composite layer);
and (4) integrating the powder layer by melting all the constituent particles.

In addition, in the solidification stage of the paste-like composition of two or more types of fine powders, it is also possible to form materials with different physical properties through a diffusion compounding reaction by heating.

In the method according to the present invention, since fine powder is used,
Furthermore, it is also possible to simultaneously generate a compound from two or more types of fine powders by diffusion sintering. This is an effective method for forming intermetallic compounds.

The thick-film fired body thus obtained may be further pressed by HIP, rolling, etc. in order to further increase the density to 6-density.

The fine powder mixture is made into a paste-like composition for ease of printing. To make a paste, an organic vehicle or the like is added to form a slurry, but for this reason, the fired thick film body tends to become porous at -1c.

If the pores in the thick film body have an adverse effect on the function, for example, the toughness deteriorates even with small pores. In such cases, the thick film body is densified by applying pressure.

Next, the present invention will be described in more detail with reference to Examples, but these are merely illustrative and the present invention should not be interpreted as being unduly limited thereby.

Example 1 An example in which the present invention was applied to a heat-resistant Ni-based superalloy-ceraminox composite material that simultaneously utilizes the workability and toughness of metal and the heat resistance and wear resistance of ceramics is shown below. The aim of the composite and the component system are summarized in Table 1.

In this example, the paste composition was applied by performing the screen printing operation shown in FIG.

Note that the composite material of the component system as shown in this example is
, is difficult to manufacture using the PVD method. This is because, with the current state of the art, it is impossible to simultaneously deposit a complex component system such as a heat-resistant Ni-based superalloy with a ceramic component.

Table 1 Aims and implementation of composite composition Using Nil superalloy (Hastelloy) as a substrate, Si3
A coating layer with a stepwise change in the N4 blending ratio was made to a thickness of 5ff1m.
I set it up only. Sintering is done by plasma annealing, making it extremely fine! Pressure for the conversion was performed by the HIP method. As the organic vehicle, PMMA acrylic dissolved in dibasic acid ester was used. The manufacturing method and manufacturing conditions are summarized in Table 2.

The composition distribution shows good controllability as shown in FIG. 2. In the figure, the concentration distribution of 5iJia shown by a curve is a designed concentration distribution, and the stepwise shape shows a stepwise concentration distribution realized by the method according to the present invention.

However, with the particle injection method, it is difficult to control the composition with high precision on the micron order as shown in FIG.

Example 2 An example in which the present invention is applied to 5iC-C, which can also be manufactured by CVD or PVD, will be shown below.

In this example, the coating operation was performed in the same manner as shown in FIG. 1, and a composite structure was manufactured.

The aim of compounding and the components to be implemented are summarized in Table 3.

A carbon material was used as a substrate, and a coating layer with a thickness of 1+wm in which the blending ratio of SiC was successively changed in stages was provided on this material. As the organic binder, ethyl cellulose dissolved in terpineol was used. The film formation time was I sec, and laser sintering was performed after film formation. The manufacturing method and manufacturing conditions are shown in Table 4.

The composition distribution shows good composition distribution controllability as shown in FIG. In the figure, the SiC concentration distribution shown by a curve is a designed concentration distribution, and the step-like shape shows a stepwise concentration distribution realized by the method according to the present invention.

However, with the particle injection method, it is difficult to control the composition with high accuracy on the micron order as shown in FIG.

Regarding the film formation rate in this example, CVD, PVD
An example of comparison with the method is shown in Figure 4. In the case of the present invention, it is indicated by O, and the controllable range is indicated by an arrow region.
In the case of the VD method, the actual value is also indicated by ○.

In either case, the mole percent of C/(C+5iC) is 1 to 1
However, the film forming rate of the method according to the present invention is significantly higher than that of the CVD method and the PVD method. Even considering the time required for sintering and HIP, it is clear that the method according to the present invention is a practical method.

(Effects of the Invention) Since the present invention is configured as described above, it is possible to reliably produce composite materials with an intentional compositional distribution or uniform fine composite materials of components or intermetallic compounds that do not melt together. It has become possible to do this, and the industrial benefits are enormous.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of continuous composite formation of the present invention; FIG. 2 is an illustration of continuous composite formation of the present invention;
Control of composition distribution of composite structure according to embodiments of the present invention 1
Explanatory diagram showing an example) FIG. 3 is an explanatory diagram showing the concentration distribution of a composite structure in an example of the present invention; and FIG. 4 is an explanatory diagram comparing film formation by CVD method and PVD method. ■ = Niscreen 2: Substrate 3: Paste 4: Paste after printing 5: Squeegee

Claims (9)

[Claims] (1) It consists of sequentially applying a plurality of paste-like compositions in which different types of fine powders are uniformly mixed by adjusting the blending ratio on a substrate, and solidifying the obtained coating layer, and the method is applied in the direction of application. A method for manufacturing a composite structure by coating, characterized by realizing a composition distribution of. (2) The method according to claim 1, wherein the thickness of each coating layer is on the order of microns or more and less than several tens of microns. (3) Claim 1: Each paste composition in which the blending ratio of different types of fine powders is changed stepwise in the thickness direction is coated one after another.
Or the method described in 2. (4) The method according to claim 1 or 2, wherein each paste composition in which the blending ratio of different types of fine powders is constant is applied over and over again. (5) As a means for solidifying the coating layer, drying and/or
or claims 1 to 3 in which heating and/or sintering is performed.
The method described in any of the above. (6) The method according to claim 5, wherein solidification is performed after each application. (7) The method according to any one of claims 1 to 6, wherein a diffusion compounding reaction is performed by heating when solidifying the coating layer. (8) The method according to any one of claims 1 to 7, wherein after solidification, the obtained thick film fired body is further pressurized and/or sintered for densification. (9) The method according to any one of claims 1 to 8, wherein the paste composition is applied using a printing method using a screen.