JPS6144141A - Material for electrode for ignition plug - Google Patents

Abstract

PURPOSE:To obtain the titled Pt-base material preventing corrosion even at the service temp. of an engine or above and having superior durability by adding a prescribed total amount of a specified amount of Ir and a specified amount of W or a specified total amount of W and one or more among Mo, Rh, Re, Ru, Co, Fe, Mn and Ni to Pt. CONSTITUTION:A Pt alloy is manufactured by adding 20.0-30.0wt% in total of 15.0-25.0wt% Ir and 0.1-5.0% W or 0.1-5.0% in total of W and one or more among Mo, Rh, Re, Ru, Co, Fe, Mn and Ni to Pt. When the Pt alloy is used as a material for an electrode for an ignition plug, the coarsening of the grains at high temp. and the abnormal erosion are prevented, and an electrode for an ignition plug having superior durability can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method for completely forming the spark gear of a spark plug.
The present invention relates to an electrode material used in the form of a chip electrode for a spark discharge portion of an electrode or a ground electrode.

Conventionally, 1, as a method of reducing electrode wear of a spark plug, a spark discharge part [a noble metal tip electrode such as platinum or platinum alloy having heat resistance and oxidation resistance was formed by electric welding means. Spark plugs have less wear and tear than spark plugs with discharge parts made of base metals such as Ninogel alloy, and can have a longer service life. Considering economic constraints and durability, the tip electrode in this case is used as a thin film of 0.1 to 0.7 mm, but when actually used in an engine, the temperature of this thin film part is 900 to 1 ooo'C or more, which is a very severe corrosion environment, but platinum-based alloys in particular become extremely unstable to corrosion in a reducing atmosphere of 900 °C or more. ing. For example, in the case of pure platinum, grain growth is extremely fast; at temperatures above 400'C, 0 grain growth begins, and at temperatures above 900'C, 0.
There is a possibility that the thin film will grow to a culm with a single crystal grain size, and when used in an engine, corrosion will proceed along the grain boundaries and cause so-called grain boundary fracture mainly caused by cracks. The life of the electrode will be significantly reduced. In addition, Shiroki Irinium alloy (Ir5~2) is known as an ignition bladder electrode material.
0% by weight], the addition of iridium increases the crystal grain growth temperature to 700-880'C, slowing down coarsening and causing less damage to the electrode.
Fire plug? [1 as a pole was missing and the VC could not be completely satisfied.

In order to completely prevent grain boundary fracture as described above, the present invention has sufficient stability even at engine operating temperatures of 900 to 1000'CVC, has a low corrosion rate, and greatly extends electrode life. (The purpose is to provide electrode materials for spark plugs.

In the present invention, platinum is composed of 15.0 to 25.0 wt. The main feature is that the platinum alloy in the range of .0 to 30.0 ffl amount % completely prevents crystal grain enlargement at high temperatures.

In the present invention, the reason why iridium't is 15.0ffii% or more is to ensure the effect of preventing coarsening of crystal grains at temperatures above 900'C, and adding more than 25.0% iridium results in hardness and poor workability. This is because mass productivity becomes poor, and tungsten, molybutton, rhodium, and rhenium are added with only iridium.

Ruthenium, cobalt, iron, manganese and Ninogel all 0
The reason why it is limited to 1 to 5% by weight is that if it is less than 0.1% by weight, coarsening cannot be prevented, and if it is more than 5% by weight, workability will similarly become difficult.

The present invention will be explained below with reference to Examples.

Example 1 All of the platinum alloys having compositions 1 to 9 shown in Table 1 were stamped with Elincott, and were forged and rolled to a thickness of 0.5mm. All rolling processes were performed. For each sample, the crystal grain growth temperature according to the crystal structure was determined by leaving it at a predetermined temperature for 7ff for 1 hour.

The results are shown in Table 1] 1T19, and all of the uninvented samples 6 to 9 showed a tendency toward coarsening of the crystal grains at a high temperature of 900"C or higher compared to the conventional teeth 1 to 3. Abnormal corrosion of the platinum surface can be effectively prevented.Sample I!
114. When iridium is added alone in Arashi 5, the effect of suppressing holes is excellent, but the bonding strength at the welded portion with the electrode material is poor, and when iridium is added in an amount of 25.0 If% or more, workability is extremely deteriorated.

Table 1 Example 2 Samples with a diameter of 0.5 mm and 19 mm of the present invention in Table 1 and the conventional example were used. One weld was made. (Power the hole plug and use the 3000cc 2-stroke engine
r An n1it long test was conducted under pmX4/4 conditions, and the fc results showed that the platinum surface of the conventional example No. 1 eroded after 100 to 150 hours, while the uninvented No. 7 showed no abnormality on the alloy surface even after 500 hours. Ta.

As mentioned above, the platinum alloy which is the mold material for the ignition bladder of the present invention has an engine operating temperature of 900 to 1000°C.
It is stable for a long time by preventing corrosion and abnormal under-corrosion at C or higher, and has excellent durability as a spark plug electrode. In addition, it can be manufactured into thin film small-diameter members with the same workability as conventional platinum alloys, and can be joined with almost the same weldability as conventional platinum alloys.

Claims (1)

[Claims] Iridium 15.0-25.0% by weight and tungsten 0
．． 1 to 5% by weight or tungsten and molybdenum, rhodium, rhenium, ruthenium, cobalt, iron, manganese,
An electrode material for a spark plug characterized by comprising 0.1 to 5% by weight of at least one member selected from nickel and 20.0 to 30.0% by weight of iridium, with the balance being platinum. .