JPH0826426B2 - Ni-based alloy for spark plug electrode of internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has particularly excellent high temperature strength, and has the melting resistance, high temperature corrosion resistance, and spark wear resistance required for spark plug electrodes of internal combustion engines. It also relates to an excellent Ni-based alloy.

[Conventional technology]

In general, for example, a material forming an ignition plug electrode of an internal combustion engine such as an automatic engine is required to have high-temperature strength, melting resistance, high-temperature corrosion resistance, and spark exhaustion resistance, and thus have these characteristics, for example: Japanese Examined Japanese Patent Sho 60-43897
Ni-based alloys described in Japanese Patent Laid-Open Publication No. 2003-242, that is, in% by weight (hereinafter,% represents% by weight), Si: 0.2 to 3%, Mn: 0.5% or less, and Cr: 0.2 to 3% , Al: 0.2 to 3%, Y: 0.01 to 1%, and a Ni-based alloy having a composition of Ni and inevitable impurities is used.

[Problems to be Solved by the Invention]

On the other hand, in recent years, there has been a marked tendency toward higher temperatures in the combustion atmosphere due to the speeding up of internal combustion engines and the use of high-octane gasoline, and the spark plug electrode is also exposed to these high-temperature combustion atmospheres. Ni-based alloys have excellent melting resistance, high-temperature corrosion resistance, and spark wear resistance in these high-temperature combustion atmospheres, but their high-temperature strength is not sufficient, so their service life is relatively short as a spark plug electrode. The current situation is that

[Means for solving the problem]

From the above viewpoints, the present inventors have conducted research to develop a material having excellent characteristics at the spark plug electrode of the internal combustion engine and further excellent high temperature strength. : 0.1-1.5%, Mn: 0.1-1%, Al: 2-5%, Co: 0.5-5%, and the balance is Ni and unavoidable impurities. It also has excellent corrosion resistance, high temperature corrosion resistance, and spark wear resistance, and therefore, when this Ni-based alloy is used as an ignition plug electrode of an internal combustion engine, it is excellent even when exposed to a high temperature combustion atmosphere. When the Ni-based alloy contains 0.1 to 2% of Cr as an alloy component, high-temperature corrosion resistance is further improved, and Y and rare earth elements are also alloy components. 0 or more of the above.
It was found that the inclusion of 001 to 0.5% would further improve the melt damage resistance and high temperature corrosion resistance.

The present invention has been made based on the above findings, and contains Si: 0.1 to 1.5%, Mn: 0.1 to 1%, Al: 2 to 5%, Co: 0.5 to 5%, and is further required. In accordance with the above, a composition containing Cr: 0.2 to 3%, one or more of Y and rare earth elements: 0.001 to 0.5%, or both, and the balance of Ni and unavoidable impurities. It is characterized by a Ni-based alloy for an ignition plug electrode of an internal combustion engine having excellent high temperature strength.

Next, the reason why the composition of the Ni-based alloy of the present invention is limited as described above will be explained.

(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, but if the content is less than 0.1%, the above-mentioned effect is desired. 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 Mn component is an essential component because it is necessary to exert deoxidizing and desulfurizing effects during melting, but its content is 0.1%.
If it is less than 0.1%, a sufficient deoxidizing and desulfurizing effect can be obtained. On the other hand, if the content exceeds 1%, the high temperature corrosion resistance is rapidly deteriorated. Therefore, the content is set to 0.1 to 1%.

(C) Al The Al component has an effect of improving high temperature strength and high temperature corrosion resistance, but if its content is less than 2%, the desired effect cannot be obtained, while its content exceeds 5%. Therefore, the workability will decrease, so the content should be 2
It was set at ~ 5%.

(D) Co Co component has the effect of imparting a higher high temperature strength in comparison with the effect of improving the high temperature strength provided by Al in the coexistence with Al. No dramatic improvement in high temperature strength was obtained, while 5
%, The effect of further improvement does not appear due to the high temperature strength, and considering the economic efficiency, the content should be 0.5-5.
Defined as%.

(E) Cr The Cr component has a function of further improving the high temperature corrosion resistance, so it is contained if necessary, but its content is 0.1
If it is less than 0.1%, the desired effect of improving the high temperature corrosion resistance cannot be obtained, while if it exceeds 2%, the melting resistance is deteriorated. Therefore, the content is set to 0.1 to 2%.

(F) Y and rare earths These components have the effect of further improving the corrosion resistance and the high temperature corrosion resistance, so they are contained as necessary, but if the content is less than 0.001%, the desired improvement in the above functions is achieved. No effect was obtained, and even if the content exceeded 0.5%, no further improvement effect was obtained, and the content was determined to be 0.001 to 0.5% in consideration of economic efficiency.

〔Example〕

Next, the Ni-based alloy of the present invention will be specifically described with reference to examples.

Using an ordinary vacuum melting furnace, the molten alloys of the present invention Ni-based alloys 1 to 19, comparative Ni-based alloys 1 to 5, and conventional Ni-based alloys 1 to 4 each having the composition shown in Table 1 were prepared. Then, the ingot was formed by vacuum casting, and then the ingot was hot forged into a round bar having a diameter of 10 mm. From this round bar, (a) cross-sectional dimension for evaluating high temperature strength: 6 mm x 2 mm high temperature tensile test specimen and high temperature fatigue test specimen with dimensions of thickness (t): 6 mm x R: 30 mm x tip width (b): 25 mm specified in JIS Z2275, (b ) Diameter: 5 mm x length: 50 mm specimen for high temperature corrosion resistance test, (c) Wire for center electrode of spark plug with diameter: 2.5 mm for evaluating spark wear resistance, and cross-sectional dimension: 2.5mm × 1.4mm wire for ground electrode, (d) Cross-sectional dimension for evaluating melting resistance: 2.5mm × 1.4m
Samples for measuring the melting start temperature of m were cut out or formed by wire drawing or hot forging, and various tests were performed under the following conditions.

The high temperature tensile test was performed at a temperature of 700 ° C. to measure the tensile strength.

High temperature fatigue test, temperature: 700 ℃, bending stress: 6kgf / m
It was carried out under the condition of m ² and non-repeatable speed of load: 3000 times / minute, and the number of times of bending until breakage was measured.

The high temperature corrosion resistance test is carried out by placing a test piece on an alumina board and forming PbO as a combustion product in the combustion gas atmosphere.
Temperature: 700 ° C in a device that can continuously supply a fixed amount of compound
After heating for 100 hours, the test piece was descaled with a wire brush, and the weight loss of the test piece was measured.

In the spark exhaustion test, the center electrode and the ground electrode were set in the spark plug with the initial gap (distance between electrodes): 0.8 mm, and this spark plug was installed in a 1800cc gasoline engine equipped with a turbocharger, the rotation speed: 5500r.pm, Time: The operation was performed under the condition of 100 hours, and the amount of increase in the gap after the test was measured.

In addition, in the melting resistance evaluation test, the melting start temperature was measured. The results of these measurements are shown in Table 1.

〔The invention's effect〕

From the results shown in Table 1, the present invention Ni-based alloys 1 to 19
It is clear that all of them have excellent high-temperature corrosion resistance, spark wear resistance, and erosion resistance equivalent to those of the conventional Ni-based alloys 1 to 4, and exhibit even higher high-temperature strength. As seen in Ni-based alloys 1 to 5, if the content of any of the constituent components (marked with * in Table 1) is outside the scope of the present invention, at least one of the above characteristics It has been shown to have inferior properties.

As described above, the Ni-based alloy of the present invention has particularly excellent high-temperature strength, and also has excellent high-temperature corrosion resistance, spark wear resistance, and melt damage resistance, so these characteristics are required. When used as an ignition plug electrode of an internal combustion engine, it has industrially useful properties such as excellent performance over a long period of time even when used under severe conditions.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Mimura 1-297 Kitabukuro-cho, Omiya City, Saitama Prefecture Central Research Laboratory, Mitsubishi Metals Co., Ltd. Kenichi Hara (56) References, Okegawa Daiichi Seisakusho, Ltd. References JP-A-55-44502 (JP, A) JP-A-63-89638 (JP, A) JP-A-51-85052 (JP, A)

Claims (4)

[Claims] 1. A composition containing Si: 0.1 to 1.5%, Mn: 0.1 to 1%, Al: 2 to 5%, Co: 0.5 to 5%, the balance being Ni and inevitable impurities (above weight%). Ni-based alloy for spark plug electrodes for internal combustion engines, which has excellent high temperature strength. 2. Si: 0.1 to 1.5%, Mn: 0.1 to 1%, Al: 2 to 5%, Co: 0.5 to 5%, and Cr: 0.1 to 2%. A Ni-based alloy for an ignition plug electrode of an internal combustion engine, which is excellent in high temperature strength, characterized in that the rest has a composition (above wt%) consisting of Ni and inevitable impurities. 3. Si: 0.1 to 1.5%, Mn: 0.1 to 1%, Al: 2 to 5%, Co: 0.5 to 5%, and one or more of Y and rare earth elements: A Ni-based alloy for an ignition plug electrode of an internal combustion engine having excellent high temperature strength, characterized in that it contains 0.001 to 0.5%, and the balance is a composition (above wt%) consisting of Ni and inevitable impurities. 4. Si: 0.1 to 1.5%, Mn: 0.1 to 1%, Al: 2 to 5%, Co: 0.5 to 5%, and Cr: 0.1 to 2%, Y and rare earths. One or more of the elements: 0.001 to 0.5%, and the balance of Ni and unavoidable impurities (the content is at least% by weight) for the ignition plug electrode of an internal combustion engine having excellent high temperature strength Ni-based alloy.