JPS61207567A - Formation of thermally sprayed ceramic film - Google Patents

Abstract

PURPOSE:To form a thermally sprayed ceramic film having superior adhesion and thermal shock resistance by thermally spraying an Ni-Cr-Al alloy on an Al base to form an underlayer and by thermally spraying ceramics. CONSTITUTION:An Ni-Cr-Al alloy is thermally sprayed on the surface of an Al or Al alloy base to form an underlayer, and a thermally sprayed ceramic film is formed on the under layer by thermally spraying ceramics such as stabilized ZrO2. Since the ceramic film has high adhesion to the Al base and superior durability, the characteristics of the Al base used under severe conditions such as the heat resistance, heat insulation and corrosion resistance at high temp. can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a ceramic thermal spray coating on the surface of an aluminum or aluminum alloy substrate.

Aluminum or aluminum alloys have excellent flexibility and thermal conductivity, and are therefore widely used in various mechanical parts, thermomechanical parts, automobile parts, and the like. Recently, however, the usage conditions for these parts have become more severe, and the materials are often damaged and cannot be used as is.

One of the methods to improve the properties of aluminum-based materials is to thermally spray various ceramics on the surface of aluminum-based materials to form a surface film to improve material properties such as heat resistance, heat insulation, and high-temperature corrosion resistance. A surface treatment technology is used.

However, when a ceramic sprayed coating 11 is formed on the surface of an aluminum base material and put into practical use, the thermal sprayed coating is heated by the environmental temperature during use and is then cooled to room temperature. When exposed under such conditions, a phenomenon occurs in which the thermal spray coating peels off from the surface of the base material.

As a means to prevent peeling of ceramic spray coating +1 = conventionally N1-A (5 to 20%), N1-0 (20%)
Alternatively, a method is generally used in which a Ni-based self-fluxing alloy metal is thermally sprayed on the base, and then a desired ceramic thermal spraying material is thermally sprayed. However, even if these materials are used for base thermal spraying, if they are subjected to thermal history in a practical environment, the thermal sprayed coating may crack, peel, or fall off.
The disadvantage is that the lifespan of the skin H is short. As a result of investigating the peeling phenomenon of ceramic sprayed coatings formed on the surface of aluminum base materials that require heat insulation or heat resistance, we found that the main cause of peeling was the heat of the aluminum base material, base spray coating, and ceramic surface spray coating. It became clear that this was due to differences in expansion coefficients and poor adhesion between the base material and the base thermal spray coating.

The present invention aims to form a ceramic sprayed coating with excellent adhesion and thermal shock resistance on the surface of an aluminum alloy base material, and is characterized by spraying a nickel-chromium-aluminum alloy as a base sprayed layer. It is said that Further, in order to improve heat insulation and heat resistance, it is most preferable to use stabilized zirconia material as the ceramic material.

The base material in the present invention is pure aluminum, An-Cu type,
A11-Mg series, AJI-9i series, AM-31-Mg
These include alloys such as AM-5i-Cu series and AM-5i-Cu series. The surface of these aluminum-based alloy base materials is often thermally spray coated with ceramic for the purpose of improving heat resistance, heat insulation, and high-temperature corrosion resistance. Ceramic spraying materials used for these purposes include oxides such as alumina, titania, and zirconia, and composite oxides containing these oxides as main components. In particular, stabilized zirconia is particularly effective in terms of heat insulation and thermal shock resistance. Are better.

The thermal expansion coefficient of aluminum alloy is 18X 10 ~2
The coefficient of thermal expansion of the ceramic ink coated on the surface is about 4 x 10-6/°C, while the coefficient of thermal expansion is 5 x 10 to 10 x 10-
8/"0-0, and the difference in thermal expansion coefficient affects the thermal shock resistance of the surface sprayed coating. In the combination of the aluminum base material and the intended ceramic sprayed coating, The coefficient of thermal expansion of the layer is intermediate between the coefficients of thermal expansion of the base material and the ceramic coating, and the melting point of at least one of the metals constituting the base layer is close to the melting point of the base material, and diffusion bonding is easy. It has been found that the strongest ceramic sprayed coating can be obtained by selecting a material that has high strength as the base spraying material.

From this point of view, as a result of studying various materials as base thermal spraying materials for aluminum base materials, it was found that excellent effects can be obtained when nickel-chromium-aluminum materials are used as base thermal spraying materials. In other words, a nickel-aluminum alloy or a nickel-chromium alloy is used as the base thermal spray layer because it is a material that contains the same type of aluminum as the base material, so it is easy to diffuse bond with the base material during thermal spraying or when used at high temperatures. higher than when used. The coefficient of thermal expansion of a thermally sprayed coating using a nickel-chromium-aluminum alloy is smaller than that of the base material aluminum or its alloy, but larger than that of an oxide ceramic, which also improves peeling resistance.

Nickel-chromium-aluminum alloy is chromium-15
~55% preferably 15-25% aluminum 4-2
An alloy containing 5% nickel and a small amount of nickel.
, Mn, Si, Y, etc., there is no problem.

The nickel-chromium-aluminum alloy referred to herein refers to a composite powder made of a nickel-chromium alloy coated with aluminum, a composite powder made by granulating nickel, chromium, and fine aluminum powder, or a composite powder made by granulating nickel, chromium, and fine aluminum powder, or a composite powder made of nickel, chromium, and aluminum fine powder, or a composite powder made by granulating fine powder of nickel, chromium, and aluminum. It may be any of the metallic bonding alloys of the components.

The thermal spray coating obtained by the present invention has good adhesion to the base material and is highly durable, so it can improve the heat resistance, heat insulation, high temperature corrosion resistance, etc. of aluminum alloy materials used under harsh conditions. It becomes possible to improve material properties.

The sprayed coating obtained by the present invention can be widely used for mechanical parts such as combustion equipment, heat dissipating mechanical parts such as heat exchangers, and automobile parts such as pistons and cylinder heads, and is particularly useful as heat-insulating and heat-resistant pistons for internal combustion engines. is important.

Next, the present invention will be explained with reference to Examples.

Example 1 Pure AM and Al1-13%Si 25mmφX10 to examine the thermal spraying adhesion of the base thermal sprayed layer to the aluminum base material
After blasting the end face of a 0 mm rod, the N1-Cr-A alloy thermal spray material of the present invention and commercially available N1-5%A alloy and Ni-20%Cr alloy as comparative examples were each coated with 5% of each.
Each book was shot to a thickness of 0.3 mm. The end surface sprayed coating of these test pieces and the mating material Pure A were bonded using the adhesive Araldye 1-AT.
-1, a tensile test was conducted after adhesion.

The test results are shown in Table 1.

(Leaving space below) Table 1 As is clear from Table 1, the i = IM strength of the sprayed coating formed using the Ni-Cr-Ai sprayed material of the present invention is higher than that of conventional N1-Ax (5) or Ni-0r. (20) is significantly improved.

Example 2 Various aluminum base materials shown in Table 1 (50+nmφx
After treating the surface of 6mmt) with #3B alumina, the various types of t'' ground spraying materials shown in Table 1 were sprayed to a thickness of 0.1mm by plasma spraying, and then the various types of t'' ground spraying materials shown in Table 1 were Thickness (1
, 3 to 0.8 mm. The particle size of the base thermal spray material is 4
4 to 105 p-m, Ceramic used for dissolution
The particle size of the thermal spray material is 10 to 44 pm.

Regarding these specimens with ceramic spray coating,
A thermal shock test was conducted by repeating the heat treatment operation of holding at 400°C for 20 minutes and then cooling with water. Thermal shock resistance was compared based on the number of heat treatments until the ceramic ink film peeled off. The results are shown in Table 2.

For comparison, a similar thermal shock test was carried out by applying ceramic spraying to a base coated with a conventional Ni-based alloy. These results are also shown in Table 2.

From the results in Table 1, it can be seen that the aluminum base material was sprayed with a chromium-aluminum alloy and then ceramic was sprayed with a conventional Ni-Cr alloy or N1-A alloy. It is clear that the thermal shock resistance is significantly improved compared to the standard.

(Margin below)

Claims (1)

[Scope of Claims] 1) A method for forming a ceramic sprayed coating, which comprises spraying a nickel-chromium-aluminum alloy as a base layer onto the surface of an aluminum or aluminum alloy base material, and then spraying a ceramic material. 2) The method for forming a ceramic thermal spray coating according to claim 1, wherein the ceramic material is a stabilized zirconia-based material.