JPS602662A - Formation of ceramics coated layer - Google Patents

Abstract

PURPOSE:To prevent a thermally sprayed ceramics layer from being cracked by the effect of thermal stress by spraying thermally heat- and fire-resistant ceramics via a mask formed continuously with prescribed apertures onto the surface of a metallic base material. CONSTITUTION:The surface of a metallic base material is preliminarily roughened by sandblasting in the stage of forming a thermally sprayed layer of ceramics having high resistance to heat and fire onto said surface. Powder of an Ni- 17Cr-6Al-0.6Y alloy is thermally sprayed thereon as a binder layer and thereafter a lattice formed by knitting heat resistant wires of a prescribed diameter or a lattice formed by combining alternately heat resistant plate materials having certain width or a material formed by blanking a prescribed shape from a heat resistant plate material having certain area is used as a mask on said surface and the powder of ZrO2-8Y2O3 is plasma-sprayed through the mask onto the surface. The ceramics coated layer divided to small blocks is formed on the surface of the metallic base material and the ceramics coated layer which has an excellent thermal fatigue characteristic and is not cracked by the effect of thermal stress is obtd.

Description

[Detailed description of the invention] 1. Regarding the method of forming.

-7,:1 Heat-resistant members made by covering the surface of gold maple with various types of heat-resistant and fire-resistant ceramics, L, and S are widely used in various industrial fields. Thermal spraying has traditionally been used to form a ceramic coating layer on the surface of a metal substrate.

Methods such as surface oxidation method, physical vapor deposition method, and chemical surface oxidation method are applied for baking, but from an industrial and productivity point of view, thermal spraying is recommended for covering the membrane of high melting point materials. The law is a common method.

In this case, the thermal expansion coefficients of the base metal and the ceramic differ by about one order of magnitude, so in environments with high temperatures or severe thermal fluctuations, the thermal expansion of both at the bonding interface between the base material and the ceramic cladding layer Thermal stress is generated due to the difference, which may cause phenomena such as cracking or peeling of the ceramic forest layer from the base material.

The above-mentioned thermal stress increases as the thickness of (t) Wt m 1 m increases; ■ it increases as the surface area of the metal body increases; ■ profiteering and ceramics; , σ) and its thermal expansion coefficient is the base material gold: 蒐.

□・I1: Ru.

t, y, :, 'In this way, ・1'1 '1. ．． ', lJ, the propensity for thermal stress and the characteristics of the ceramic layer are all contradictory, and this has been a serious problem for the manufacture of heat-resistant members. In particular, the thermal fatigue resistance of the ceramic coating layer is largely dependent on thermal stress, which affects the service life of the heat-resistant member itself. In other words, even if the cracks and peeling that occur in the ceramic layer due to thermal stress initially occur in a very small area, these cracks and peeling phenomena will propagate to the entire cover layer in a short period of time. However, the coating layer may eventually collapse.

For this reason, conventionally, a layer of a material having an expansion coefficient intermediate between the base material and the ceramic frame layer is interposed between the two to form a so-called thermal stress Lk k IB. Alternatively, there was a limit to the improvement of ceramic labor properties.

Therefore, covered aF? ; There is a strong desire for a method for manufacturing a heat-resistant ceramic forest cover member having a large thickness of i, a large cedar ridge area as a whole, excellent FA fatigue characteristics, and a long service life.

[Purpose of the invention]

The present invention solves the above-mentioned problems and makes ceramics v1
The object of the present invention is to provide a method for forming a ceramic coating layer that is thick, has a large area as a whole, and has excellent thermal fatigue properties without impairing the functions performed by the eight layers.

[Summary of the invention]

The present inventors developed the method of the present invention by focusing on the following points. First, the thermal stress that causes the collapse of the ceramic coating layer propagates in the in-plane direction due to thermal strain generated in the in-plane direction of the layer. From this, it can be seen that if the area of the covering layer is made smaller, the area covered by
Thermal stress within - should be smaller overall.

fA2 is that the ceramic overlying layer formed by thermal spraying is generally not a porous layer but a layer with a large number of continuous open pores distributed, and therefore, these pores in the layer alleviate thermal strain and This means that it suppresses the generation of thermal stress °ai, and at the same time prevents the propagation of cracks throughout the layer even if cracks or the like occur within the layer.

Based on the above two points of interest, the authors of the present invention consciously formed a space in the ceramic combed R-piece that could achieve the above-mentioned open pores e>'Ot, thereby reducing the overall area of the coating layer. He came up with the idea that a nucleated layer with excellent thermal fatigue properties could be formed by dividing the core space into small compartments, and as a result of extensive research, he was able to complete the method of the present invention. .

That is, the present invention involves spraying ceramics onto the surface of a metal base material through a mask means in which a plurality of openings having a predetermined planar shape are arranged. [This is a method for forming a ceramic nucleation layer.

In the present invention, the base material may be any type of metal as long as it is a metal that can serve as a base material for a heat-resistant member and that can be obtained by VB-depositing a ceramic layer on the surface of the metal. The same applies to ceramics used for forming the coating layer.

The most important feature of the method of the present invention is that a mask means as described below is interposed between the base material and the spray gun when ceramics are sprayed.

The mask means according to the present invention has a plurality of openings arranged in a predetermined opening shape. For example, a mesh made by interweaving heat-resistant wires of a predetermined wire diameter, a lattice made by alternately combining heat-resistant plates with a certain width, parts of a predetermined shape regularly punched from heat-resistant plates of a certain area, etc. I can give it to you. In this case, the shape of the frontage portion may be any shape such as a triangle, a quadrangle, a pentagon, or a circle, and the individual sizes thereof are not particularly limited. However, it is preferable that the openings are arranged in a regular arrangement.

In the present invention, ceramics are thermally sprayed with the above-described mask means interposed between the base material and the thermal spray gun.

The molten or semi-exploded ceramic particles ejected from the gun rush onto the surface of the substrate. At that time, among the ceramic particles that have reached the mask means, those that pass through the openings reach the surface of the base material and there, the phase detection h3
form.

Meanwhile, the openings of the mask means reached between each other:,:,
'), when a plurality of ceramic covering layers are formed independently of each other, the ceramic covering layer is not formed in the areas where the openings of the masking means are projected, so to speak, at the positions where the skeleton parts of the masking means are projected. It follows that a 11 m long zone occurs within the entire ceramic layer.

In this way, in the method of the present invention, it is possible to form a coating layer on the surface of a base material in which a countless number of small ceramic coating layers are arranged independently of each other and in contact with Vh through separation zones. At this time, the planar shape of the small covering layer, the width of the separation zone, etc. can be changed by appropriately selecting the opening pattern of the mask means.

When the heat-resistant member manufactured by the method of the present invention is exposed to, for example, a high-speed fluid, only the outermost surface of the covered layer is melted so as not to disturb the flow of the high-velocity fluid due to the separation zone portion of the covering layer. All you have to do is make it a continuous surface.

(lN738LC) plate material surface particle size 1m Al: 1
1 Moth current value 700A, fi ('Ni- under the condition of throne 34V
17Cr-6AQ-0.6Y alloy powder was plasma sprayed. This sprayed layer is a bonding layer. A mesh mask made of SUS 304 wire rods having a thickness of 100 μm and a wire diameter of 1 wφ knitted together at 15 cm intervals was set 2 mm apart from the sprayed layer of the plate material. Here, the spraying distance is 100 tqn, the current f, q
800 A *ZrO, -s under voltage value 34V (7) condition
y, o, ceramic powder thickness 300j1m-280
A thermal fatigue test (in the atmosphere) was performed by cooling for 60 minutes at G, and the presence or absence of cracks in the yuzu cover layer was observed with the naked eye. The result is expressed as the number of thermal cycles until crack initiation tp! It is shown in Table 1. The same except that a mask was not used for comparison; -: Example 2 , l, (゛, The dimensions of the plate were 20 m square and 3 m thick. 1, -2'' The masking means had a wire diameter Ceramic coating was carried out in the same manner as in Example 1, except that 5US304 wire rods of 0.5 tuaφ were knitted together at 7-way intervals, and the mask means was placed directly on the thermal sprayed layer of the plate material. Formed the Hime layer.

The thermal conductivity in the thickness direction of the obtained member was measured by a laser flash method. The results are shown in Table 2.

For comparison, the results of the same comparative example sample described in Example 1, except that the thickness was 450 μm, are also shown.

A ceramic coating layer was formed on the outside of the yarn in the same manner as in Example 1, except that two masks were used for the second rotation.

The results of the thermal fatigue property test were also the same as in Example 1.

〔Effect of the invention〕

As is clear from the above explanation, according to the method of the present invention, the formed tormented layer does not have a large change in thermal conductivity compared to the conventional one, and has excellent pAR properties. Therefore, even if the thickness of the ceramic Y-covered layer is increased or the overall area is increased, cracks in the layer or weak aging from the base material are suppressed; (2) The industrial value of the method of the present invention is extremely great because it has the effect of shortening the service life.

Claims (1)

[Claims] 1. A method for forming a ceramic covering layer, which comprises spraying ceramics onto the surface of a metal base material through a mask means in which a plurality of openings having a predetermined opening shape are arranged.