JPS61159566A - Coating method of metallic or ceramic base material - Google Patents

Abstract

PURPOSE:To form a coated layer having the impact strength resistance, the wear resistance and the corrosion resistance on the surface of a metallic or ceramic base material by applying a hot-hydrostatic compression method on a sprayed coated layer which is formed on the surface of the metallic or ceramic base metal to make it dense and vanishing a pore. CONSTITUTION:The surface of a metallic base material such as e.g. mild steel, stainless steel or a ceramic base material consisting of a sintered body such as Al2O3, SiC is blast-treated by an alumina grid. A sprayed coated film is formed by thermally-plasma spraying the powder such as Ni on the surface of the blast-treated base material in the nonoxidizing atmosphere such as Ar. Thereafter a hot-hydrostatic compression method (HIP treatment) is applied on the above-mentioned sprayed coated layer to make it dense. As a result, a pore interposed in the inside part of the coated layer is removed and it is made dense and the mechanical strength characteristic such as the wear resistance, the corrosion resistance, the impact resistance and the peel resistance is given on the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of coating metal or ceramic substrates. More specifically, the present invention relates to a method of forming a dense coating layer with high wear resistance and corrosion resistance on the surface of a metal or ceramic substrate by thermal spraying.

[Prior Art] Mechanical devices are usually composed of several parts.
They are manufactured from materials that have properties that can withstand the areas and environments to which they are applied. For example, resistance! High-strength materials such as high-strength steel are used for parts that require high impact strength, and M-Cr is used for parts that are used in highly corrosive environments.
Corrosion-resistant materials such as AIY (M is metal) and wear-resistant materials such as cermet are used for parts that are subject to severe wear, and these parts materials are generally expensive. Therefore, instead of constructing the entire part with expensive materials, a method has been proposed in which only the surface is coated with a layer of high-strength material, corrosion-resistant material, or wear-resistant material. A method is known in which a coating material is thermally sprayed onto the surface of a base material to form a strong coating layer.

[Problems to be Solved by the Invention] However, forming a coating layer by a thermal spraying method involves applying a coating material made of particles or powdered metal or ceramic in a molten or nearly molten state to a part base material made of metal or ceramic. Since the MH is sprayed onto the surface and laminated, many pores are present in the MH, and a dense coating layer cannot be formed.

In other words, if pores are present, the coating layer will float or peel off.
Significantly reduces the corrosion resistance of the coated surface. In order to solve this problem, attempts have been made to narrow the particle size range of the powder coating material used for thermal spraying, but the coating layer obtained only by thermal spraying has a high heat resistance TtJ impact strength. Furthermore, internal thermal stress is generated due to thermal contraction when the molten rfI material particles cool and solidify on the surface of a metal or ceramic base material, and this stress accumulates, causing damage to the base material and peeling of the coating layer. Such phenomena are more likely to occur as the surface area of the base material and the layer thickness become larger, and these phenomena are considered to be a major drawback in forming a coating layer by thermal spraying.

[Means for solving the problem] When forming a coating layer with high impact resistance, abrasion resistance, or corrosion resistance on the surface of a component base material made of metal or ceramic by thermal spraying, pores are created in the coating layer. As mentioned above, it is important that the coating material particles are not incorporated, and as a result of various investigations into the means for this purpose, the present inventors have found that after thermal spraying the coating material particles, hot isostatic pressure is applied to further densify the sprayed surface. By performing compression treatment, pores disappear,
The present invention was achieved based on the knowledge that a dense coating layer having impact resistance, abrasion resistance, and corrosion resistance is formed.

That is, the present invention provides a metal or ceramic substrate characterized in that a powder coating is thermally sprayed onto the surface of a metal or ceramic base material, and the formed thermally sprayed coating layer is densified by applying a hot isostatic pressing method. Alternatively, the subject matter is a method of coating a ceramic substrate.

To further explain the present invention, the base materials to which the coating method of the present invention is applied include, for example, metal base materials such as mild steel, stainless steel, and various alloys, AJlzOa
, Zr 02. Examples include ceramic base materials made of sintered bodies such as Si C and AiN.

Among these, in the case of the metal base material, the surface of the base material is preferably roughened by metal blasting or sandblasting before forming a coating layer on the surface by thermal spraying.

The coating material to be thermally sprayed onto the surface of a metal or ceramic substrate may be a finely powdered metal such as Ni, An, W, etc.
(7) J: metal, AizOa, TiO, zrO
Examples include particulate ceramic materials consisting of one type or a mixture of two or more of Y2O3 and the like, and these are usually 25
The particle size is adjusted to 0 mesh or less.

Formation of the NR by thermal spraying can be carried out by known methods, but in particular, the NR of 10.0
Plasma spraying is most preferred because it can easily achieve a high temperature of 0° C. or higher. Further, the thermal spraying is performed at 300 T, for example.
It is preferable to carry out under reduced pressure of orr or less. By performing the process under reduced pressure, the substrate to be coated will not be oxidized during preheating for thermal spraying (and a dense coating layer will be formed, and the capsules will not be oxidized during the subsequent isostatic pressing process). It has the advantage of making it possible to densify the N layer without using it.When forming a thermal spray coating layer on the surface of a base material by thermal spraying, thermal expansion between the base material and the coating composition is avoided. If there is a concern about a decrease in adhesion strength or thermal shock strength due to different coefficients, use a powder made of a composition with a thermal expansion coefficient intermediate between these materials between the thermal spray coating layer on the surface and the base material. A powder material consisting of a material or a mixture of the components of the surface thermal spray coating layer and the base material components is thermally sprayed onto the surface of the substrate to form a base coating layer (undercoat) that functions as a buffer layer. It is also possible to form a top coat I! layer (top coat).

When a coating layer is formed on the surface of a substrate by thermal spraying in the atmosphere, it is unavoidable that 3 to 15% of fine pores of 5 to 60 microns are present inside the coating layer, which makes the coating layer brittle. It is the cause of

Therefore, the method of the present invention uses a hydrostatic compression method (hereinafter referred to as HIP) to remove the pores present in the coating layer formed by thermal spraying.
is applied and removed to transform it into a strong, densified coating layer. One of the methods for HIP treatment is to put the base material on which the thermally sprayed N layer is formed into a capsule and vacuum seal it, or to cover it with a glassy coating. Another method is to apply a plasma flame to the surface of the substrate in order to seal the pores present in the N layer of the base material on which the solvent solution rttm is formed.

[Operation] Since the pores present inside the thermal spray coating layer formed on the surface of the base material by the thermal spraying method are removed by the l-11P treatment,
The coating layer is further densified and its mechanical strength is strengthened, and at the same time, the adhesion to the base material becomes strong.

[Examples] Next, the present invention will be explained by examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 A square sprayed surface 1 with one side of 30 m/m and a thickness of 1
0m/m plate piece 2 and a length of 150m/m provided in the center.
A test piece as shown in FIG. 1 was prepared, which consisted of a cylindrical handle 3 with a diameter of 12 m/m. The material is mild steel. The sprayed surface 1 of this test piece was cleaned and blasted with an alumina grid to give a surface roughness of about 70 am. Next, working gas Ar,
Working current 600A, working voltage 29V, spraying distance -90m/
280 mesh or less was plasma sprayed onto the sprayed surface 1 to a thickness of 0.5 m as shown in Figure 2.
/m of thermal spray coating Ff4 was formed. This thermal sprayed N layer 4
The porosity and adhesion strength were measured using the following method.

Porosity: The specific gravity of the film was determined by the Archimedes method and the porosity was calculated.

Adhesion strength: fix the plate piece 2, pull out the cylindrical handle 3,
The tensile strength at break is determined by measuring the stress at that time.

As a result of the above measurements, the porosity is 9.3% and the adhesion strength is 1kg.
f/IIII''.Next, the sprayed surface 1 of a separately prepared test piece shown in Fig. 1, made of the same material and having the same dimensions.
A solvent coating layer 4 was formed under the same conditions as above, and the tube was sealed in a Pyrex glass tube and subjected to HIP treatment. The HIP processing conditions at this time are 1r! 1.110
0°C, 1000k<1/crA, 2 hours. When the porosity and adhesion strength were measured using the same method as above, the porosity was 0%, and the adhesion strength was 2.
It was 5 kgf/n+ni'. As is clear from the results, the HIP treatment caused the pores in the solvent coating layer to disappear and become denser, and the solvent coating layer on the surface was strongly adhered to the base material.

Example 2 A test piece was made of 18-8 stainless steel, had the shape shown in FIG. 1, and had the same dimensions as Example 1. The sprayed surface 1 of this test piece was cleaned in the same manner as in Example 1, and blasted with an alumina grid to reduce the surface roughness to about 70.
It was set as μm. Next, working gas: Ar, working current 450A,
Work 11 Jffi pressure 30v.

Spray distance 1111 to 90m/m, 97.5% AizO
A-2.5% Ti0z powder (200+325.++y powder) was plasma sprayed onto the sprayed surface 1 to form a sprayed coating layer 4 having a thickness of 1 m/m as shown in FIG. Regarding this thermal spray coating 114, the porosity and adhesion strength were measured using the same method as in Example 1, and the results were 8.0 for each.
%, 1.3 kgf/m♂.

Next, a thermally sprayed coating layer 4 was formed under the same conditions on the thermally sprayed surface 1 of a separately prepared test piece shown in FIG. After applying a flame and remelting only the surface, sealing the hole, HI under the conditions of temperature 1350℃ and pressure 2000kg/-
P treatment was performed.

The porosity and adhesion of this product were measured in the same manner as above, and the porosity was 0.5%.

The adhesion strength was 14 k (If/mri"). In this case as well, as in Example 1, the pores in the sprayed coating layer disappeared and became dense due to the HIP treatment, and the sprayed coating layer on the surface was strongly bonded to the base material. It can be seen that it is closely attached to

Next, a test piece on which a thermal spray coating layer 4 was formed only by the above thermal spraying, and a test piece after forming a thermal spray coating layer 4 with a solvent)-
The abrasion resistance of the test piece subjected to the 11P treatment was evaluated. Wear resistance was evaluated using a human-sensitive rapid abrasion tester using a standard rotary plate with a diameter of 30 m/m and a thickness of 3 m/m over a friction distance of 100 m.

This was done by determining the specific wear amount with respect to the change in friction speed under the condition of a final load of 6.4 kg on the friction surface. The results are shown graphically in FIG. This figure shows the alt quasi-rotating plate grain WA, grain size 46, degree of bonding J, and group llAm.
These are the results of a dry sliding wear test on the surface of the sprayed coating layer 4 polished with a grindstone. As is clear from this figure, H after thermal spraying
Solvent solution Wt formed by the method of the present invention that performs IP treatment
It can be seen that the layer has a wear resistance of 2 degrees or more compared to a thermally sprayed coating layer formed only by thermal spraying without HIP treatment.

Example 3 The material is made of AizOa sintered body, and the 11i! ! A test piece having the shape shown in 1 and the same dimensions as in Example 1 was prepared.

Working gas Ar1 working current 6
00A, operating voltage 32V, spraying distance 90m/m, 9
A mixture consisting of 0% Zr0z-10% YzOs and A9
．． A mixture with zO3 (mixing ratio 1:1) with particle size adjusted to 250 mesh or less is plasma sprayed to a thickness of 0.
．． 5m/m base thermal spray coating! l! (undercoat) was formed.

Furthermore, a mixture consisting of 90% Zr0z-10% Y2O3 whose particle size was adjusted to 250 mesh or less was plasma sprayed on top of it under the same conditions as above, and a thickness of 1.0 m/min was applied.
A surface layer tA'IJI covering layer (top coat) of m was formed. The porosity of this product was measured using the same method as in Example 1, and the base thermal spray coating layer was 9.0%1.
The surface thermal spray coating layer is 15.0%, the adhesion strength is 0,
Next, the base molten copper coating layer and the surface molten copper coating layer were applied under the same conditions to the sprayed surface 1 of a separately prepared test piece shown in Figure 1, made of the same material and of the same size. A layer is formed and sealed in a high silica glass tube.)
-IIP treatment was performed. The HIP processing conditions at this time are:
1111350℃, 1500! J/crA, 2 hours. Regarding this, thermal sprayed NJ! The porosity and adhesion strength of the entire l+ were measured. As a result, the porosity was reduced to 1.5%, and the adhesion strength was improved to 12. , exhibits a high heat insulating effect on the base material, but on the other hand, has low mechanical strength.

Therefore, there are restrictions on the use of parts requiring higher mechanical strength. However, by using the coating method according to the method of the present invention, the adhesion strength is e-0-5kOf
/111112"-12kof/l11m", it is possible to form a thermal spray coating layer that exhibits a heat insulating effect. For example, HIP conditions are 1350℃, 1500℃
k (Jloll, 2 hours, strong adhesion Ml 10 kgf
/mtf) A solvent liquid iis is obtained, but in this case, the heat insulation effect decreases by about 20% in a high temperature range of 1000°C, for example. However, it is possible to form a thick coating layer by the method of the present invention, and by increasing the thickness by 20%, the same heat insulation effect can be achieved. This is useful, for example, as a heat-insulating coating component used in parts of the engine that experience strong vibrations, such as the surroundings of the engine.

[Effects of the Invention] According to the present invention, a metal or ceramic base material, which becomes a mechanical structural part, has a thermally sprayed coating layer formed on its surface using a solvent.
Furthermore, since the hydrostatic compression method is applied, the pores inside the coating layer are removed and densified, giving the surface mechanical strength properties such as abrasion resistance, corrosion resistance, impact resistance, and peeling resistance. Granted.

Therefore, since materials with expensive mechanical properties are not used for the entire base material of machine V & structural parts, it is possible to obtain mechanical structural parts extremely economically, and its engineering utility value is great. be.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the base material test piece used in the example, Fig. 2 is a perspective view showing a state in which a thermal spray coating layer is formed on this test piece, and Fig. 3 is a perspective view of the base material test piece used in Example 2. I investigated the thermal spray coating I-layer B! It is a graph showing the relationship between friction speed and specific wear amount.

Claims (1)

[Scope of Claims] 1. A metal or ceramic substrate characterized in that a coating material is thermally sprayed onto the surface of the metal or ceramic substrate, and the formed thermally sprayed coating layer is densified by applying a hot isostatic compression method. How to coat the material. 2. The method for coating a metal or ceramic substrate according to claim 1 or 2, wherein the coating material is made of metal or ceramic.