JPS6227392A - Steeping member for aluminum molten alloy - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an immersion member used when casting or die-casting an aluminum alloy.

[Conventional technology]

When casting or die-casting aluminum alloys containing elements such as Si, Mg, Ni, Cu, etc., parts made of cast iron, silicon carbide, silicon nitride, etc. should be used in the parts that will come into contact with or be immersed in the molten aluminum alloy. For example, the heater 2 used to maintain the temperature of the molten metal 1 as shown in FIG. Used in an immersed state. Similarly, materials such as silicon nitride have been used for the molten metal transport pipe 4 as shown in FIG.

[Problems with conventional technology]

However, in the above-mentioned parts made of cast iron, silicon carbide, silicon nitride, etc., some of the elements constituting the parts react with the aluminum alloy and leak into the molten metal, contaminating the molten metal or reducing the strength of the parts themselves. However, the lifespan was unsatisfactory due to problems such as deterioration and decreased durability.

For example, especially the outer surface of the protective tube 3 that comes into direct contact with the molten metal 1 shown in FIG. There were many cases of breakage due to thermal stress, mechanical stress, impact, etc.

[Means for solving problems]

In order to avoid the above-mentioned reactions with aluminum alloy elements in particular, boron nitride-based materials with the highest reaction resistance with these aluminum alloy elements are used, especially among the above materials, those with the highest degree of reaction with molten aluminum alloys. It is characterized by being constructed by being adhered to the surface of a substrate made of a small silicon nitride ceramic.

〔Example〕

FIG. 2 shows a partially enlarged cross-sectional view of a member according to an embodiment of the present invention, in which the base body 1 is made of silicon nitride π ceramic with high heat resistance, and its shape is similar to that of the protection tube 3, transport tube 4, etc. shown in FIG. , and other members that can be formed into any shape depending on the purpose of use, such as a container for storing molten metal. The outer surface of the base of such silicon nitride ceramics is coated with a boron nitride material that has high reaction resistance with alloy elements such as aluminum and SL Mg on the parts that come into contact with the molten metal! M is attached. The coat J coated on the surface of the substrate in this way
The results of investigating the reaction characteristics between the 15M thickness and various aluminum alloys are shown in Table 1. The temperature of the molten metal in this reaction experiment was set at 750°C.

Table 1 shows that members coated with boron nitride (BN) coating layers M of various thicknesses d were immersed (contacted) in molten metals of various aluminum alloys for 200 hours, then pulled out and treated with various aluminum alloys. , which shows the reactivity with silicon nitride ceramic forming the substrate K. Those marked with an X are those in which a large reaction layer with aluminum, alloying elements, and silicon nitride was formed, and a significant decrease in strength was observed. In addition, in the case of Δ, diffusion of the aluminum alloy element into the substrate was observed, but no reaction layer was formed. On the other hand, in the case marked O, there was almost no diffusion of the aluminum alloy element, and therefore no reaction layer was observed.

Furthermore, the thickness d of the coat 5M is 150un and 190μ.
As the value of K increases, the reaction between aluminum, alloying elements, and the silicon nitride ceramic forming the substrate K disappears (
Although the grain size increased, peeling development from the surface of the substrate frequently occurred, which was unsuitable.

The surface roughness of the substrate to which the coating layer M is applied is 20.
The following methods are suitable, and the coating layer M can be applied by spraying a slurry made by mixing boron nitride powder with an organic solvent, by a gutter cleaning method, or by an ion blating method. .

〔Effect of the invention〕

As mentioned above, by depositing a boron nitride coating layer on the surface of a highly heat-resistant silicon nitride ceramic ceramic substrate, the degree to which a reaction layer is formed between aluminum, alloying elements, and the substrate is increased. As a result, the durability of protective tubes, transport tubes, jigs, tools, containers, etc. used for casting and die-casting of aluminum alloys made of such materials,
Lifespan can be significantly improved.

[Brief explanation of the drawing]

Figure 1 (A) is a fractured cross-sectional view showing a temperature-maintaining heater made of a silicon carbide protective tube immersed in molten aluminum alloy, and Figure 1 (B) is a sectional view of the molten aluminum alloy 78 being transported. FIG. 2 is a partially enlarged sectional view of the member of the present invention applied to molten aluminum alloy. ■= Nialuminum gold/8 hot water 2: Heater 3: Protective tube: Base M: Coating layer

Claims (1)

[Claims] As a member that comes into contact with the molten aluminum alloy, the base is made of a silicon nitride ceramic, and a boron nitride coating layer is coated on at least the surface of the base at the part that comes into contact with and is immersed in the molten metal. Immersion parts for molten aluminum alloy.