JP2587864B2 - Spark plug electrode material for internal combustion engines - Google Patents

Description

The present invention relates to a spark plug electrode material for an internal combustion engine having excellent high-temperature strength and excellent erosion resistance, high-temperature corrosion resistance, and spark wear resistance. It is about.

[Conventional technology]

In general, for example, as a material for forming a spark plug electrode material of an internal combustion engine such as an automatic engine, high temperature strength, erosion resistance, high temperature corrosion resistance, and spark wear resistance are required, and therefore, these materials were provided. For example, Japanese Patent Publication No. 60-4389
Patent No. 7 discloses a Ni-based alloy, that is, by weight% (hereinafter,% indicates weight%), containing: Si: 0.2 to 3%, Mn: 0.5% or less. For example, a Ni-based alloy containing 2% or more of 3%, Al: 0.2 to 3%, and Y: 0.01 to 1%, and a balance of Ni and unavoidable impurities is used.

[Problems to be solved by the invention]

On the other hand, there has been a remarkable tendency to increase the temperature of the combustion atmosphere due to the recent increase in the speed of internal combustion engines and the use of high-octane gasoline, and accordingly, the spark plug electrode materials are also exposed to these high-temperature combustion atmospheres. Conventionally, spark plug electrode materials composed of Ni-based alloys show good erosion resistance, high temperature corrosion resistance, and spark wear resistance in these high-temperature combustion atmospheres, but are relatively short due to insufficient high-temperature strength. At present, the service life is reached in hours.

[Means for solving the problem]

In view of the above, the present inventors have conducted research to develop a material that has the characteristics required for a spark plug electrode of an internal combustion engine and further has excellent high-temperature strength. : 0.1 to 1.5%, Mn: 0.1 to 0.65%, Al: 3.1 to 5%, at least one of rare earth elements: 0.001 to 0.
The spark plug electrode material, which is composed of a Ni-based alloy containing 5% and the balance of Ni and unavoidable impurities, has excellent high-temperature strength and excellent erosion resistance, high-temperature corrosion resistance, and spark wear resistance. Therefore, even when exposed to a high-temperature combustion atmosphere, excellent performance can be exhibited for a remarkably long period.
It has been found that when 0.1 to 2% of Cr is contained as an alloy component in the base alloy, the high-temperature corrosion resistance is further improved.

The present invention has been made on the basis of the above findings, and includes one or more of Si: 0.1 to 1.5%, Mn: 0.1 to 0.65%, Al: 3.1 to 5%, and rare earth elements: 0.001 to 0.1.
5%, and, if necessary, Cr: 0.1 to 2%, with the balance being Ni-based alloy having a composition comprising Ni and unavoidable impurities. It has features.

Next, the reason why the component composition of the Ni-based alloy constituting the spark plug electrode material of the present invention is limited as described above will be described.

(A) Si The Si component has an effect of improving high-temperature corrosion resistance and spark wear resistance without impairing the erosion resistance provided by the Ni component. No effect, while its content is 1.5%
When the content exceeds 0.1%, the erosion resistance tends to deteriorate. Therefore, the content is set to 0.1 to 1.5%.

(B) Mn The Mn component is an indispensable component because it needs to exert a deoxidizing and desulfurizing action during melting, but its content is 0.1%.
If the content is less than 0.65%, sufficient deoxidation and desulfurization effects cannot be obtained. On the other hand, if the content exceeds 0.65%, the high-temperature corrosion resistance rapidly deteriorates. Therefore, the content is set to 0.1 to 0.65%.

(C) Al The Al component has an effect of remarkably improving high-temperature strength and improving high-temperature corrosion resistance.
If the content is less than 5%, the desired effect cannot be obtained, while if the content is more than 5%, the workability is reduced. Therefore, the content is set to 3.1 to 5%.

(D) Rare earth The rare earth component has an effect of further improving the erosion resistance and high-temperature corrosion resistance. However, if the content is less than 0.001%, a desired improvement effect cannot be obtained in the above-mentioned effect, while the content is reduced. Even if it exceeds 0.5%, no further improvement effect can be obtained, and the content is determined to be 0.001 to 0.5% in consideration of economy.

(E) Cr The Cr component has an effect of further improving high-temperature corrosion resistance, and is therefore contained as necessary.
If the content is less than 2%, the desired effect of improving the high-temperature corrosion resistance cannot be obtained, while if the content exceeds 2%, the erosion resistance deteriorates. Therefore, the content is set to 0.1 to 2%.

〔Example〕

Next, the spark plug electrode material of the present invention will be specifically described with reference to examples.

Using a normal vacuum melting furnace, a Ni-base alloy melt having the component composition shown in Table 1 was prepared, formed into an ingot by vacuum casting, and then the ingot was subjected to hot forging to have a diameter of 10 mm.
And from this round bar, further cut out, or by wire drawing or hot forging, with a center electrode material of diameter: 2.5 mm,
Cross-sectional dimensions: spark plug electrode materials of the present invention (hereinafter referred to as electrode materials of the present invention) 1 to 3 consisting of a ground electrode material of 2.5 mm × 1.4 mm and conventional spark plug electrode materials (hereinafter referred to as conventional electrode materials)
(A) Cross-sectional dimensions for evaluating high-temperature strength: 6 mm x 2 mm
And a high-temperature fatigue test specimen having dimensions of thickness (t): 6 mm x R: 30 mm x tip width (b): 25 mm specified in JIS Z2275, and (b) diameter: Specimen for high-temperature corrosion resistance test with dimensions of 5 mm x length: 50 mm, (c) Cross-sectional dimension for evaluating erosion resistance: 2.5 mm x 1.
A 4 mm sample for measuring a melting start temperature was formed.

Regarding the above-mentioned electrode materials 1 to 3 of the present invention and conventional electrode materials 1 to 4, the center electrode material and the ground electrode material are set on the spark plug with an initial gap (distance between electrodes): 0.8 mm, and this spark plug is turbocharged It was installed in a mounted 2000 cc gasoline engine, operated under the conditions of rotation speed: 5500 rpm and time: 100 hours, and the amount of increase in gap after operation was measured. Based on the measurement results, spark wear resistance was evaluated.

In addition, the characteristics of the above-described electrode materials 1 to 3 of the present invention and the conventional electrode materials 1 to 4 were evaluated by performing tests under the following conditions using the above-described various specimens.

The high temperature tensile test was performed at a temperature of 800 ° C., and the tensile strength was measured.

The high temperature fatigue test was performed at a temperature of 800 ° C and a bending stress of 5 kgf / m.
m ² , the load was repeatedly applied at a rate of 2000 times / minute, and the number of bendings before breaking was measured.

The high-temperature corrosion resistance test is performed by placing the specimen on an alumina boat and forming PbO as a combustion product in a combustion gas atmosphere.
Temperature: 800 ° C in a device that can continuously supply compounds quantitatively
Was carried out under the condition of heating and holding for 50 hours. After the test, descaling was carried out with a wire brush, and the weight loss of the test piece was measured.

In the erosion resistance evaluation test, the melting start temperature was measured. Table 2 shows the measurement results.

〔The invention's effect〕

From the results shown in Tables 1 and 2, the electrode materials of the present invention 1 to 3
It is clear that has excellent high-temperature corrosion resistance, spark abrasion resistance, and erosion resistance, and has a much higher high-temperature strength than conventional electrode materials 1 to 4.

As described above, the spark plug electrode material of the present invention has excellent high-temperature strength, and also has excellent high-temperature corrosion resistance, spark wear resistance, and erosion resistance. It has industrially useful characteristics such as excellent performance over a long period of time even when used.

Continued on the front page (72) Akira Mimura 1-297 Kitabukurocho, Omiya City, Saitama Prefecture Inside of Central Research Laboratory, Mitsubishi Metal Corporation (72) Nobuyoshi Kurauchi 1230 Kamijiya, Okegawa City, Saitama Prefecture Mitsubishi Metal Corporation Okegawa Daiichi Examiner, Masaki Suzuki

Claims (2)

(57) [Claims] (1) Si: 0.1 to 1.5%, Mn: 0.1 to 0.65%, Al: 3.1 to 5%, at least one of rare earth elements: 0.001 to 0.1.
An ignition plug electrode material for an internal combustion engine, comprising: a Ni-based alloy containing 5% by weight, with the balance being Ni and an unavoidable impurity (more than weight%). 2. Si: 0.1 to 1.5%, Mn: 0.1 to 0.65%, Al: 3.1 to 5%, at least one of rare earth elements: 0.001 to 0.1.
5%, and Cr: 0.1 to 2%, and the balance is made of a Ni-based alloy having a composition (more than weight%) of Ni and inevitable impurities. Spark plug electrode material.