Spark plug with nickel alloy electrode base material

A spark plug comprising:

• a center electrode having, at its tip end portion, a consumption-resistant portion made of a nobel metal or a composite material containing a noble metal as a predominant component;
• an insulator surrounding the center electrode;
• and
• a ground electrode disposed such that a side surface of a tip end portion of the ground electrode faces, in parallel, a tip end surface of the center electrode, to thereby form a parallel aerial discharge gap, wherein
• an electrode base material, which forms at least a surface layer portion of the center electrode, is formed of an Ni alloy which contains Ni as a predominant component and Cr in an amount of 1.5 to 9% by mass and Fe in an amount of 1 to 5% by mass as a secondary component, and has a coefficient of thermal conductivity of 17 to 30 W/m-K.

A spark plug comprising:

• a center electrode;
• an insulator surrounding the center electrode;
• and
• a ground electrode positioned relative to a tip end portion of the insulator and a tip end portion of the center electrode such that a spark discharge gap is formed between the ground electrode and the tip end portion of the center electrode, and creeping spark discharge along a surface of the tip end portion of the insulator can occur at the spark discharge gap, wherein
• an electrode base material which forms at least a surface layer portion of the center electrode is made of an Ni alloy containing Ni as a predominant component and further containing, as a secondary component, an element selected from the group consisting of Ru, Zn, V, Co, Nb, Ta and Ti, wherein the Ni alloy constituting the electrode base material contains Ni in an amount of 80% by mass or more.

A spark plug comprising:

• a center electrode having, at its tip end portion, a consumption-resistant portion made of a noble metal or a composite material containing a noble metal as a predominant component;
• an insulator surrounding the center electrode;
• and
• a ground electrode disposed such that a side surface of a tip end portion of the ground electrode faces, in parallel, a tip end surface of the center electrode, to thereby form a parallel aerial discharge gap, wherein
• an electrode base material, which forms at least a surface layer portion of the center electrode, is formed of an Ni alloy which contains Ni as a predominant component and Cr in an amount of 1.5 to 9% by mass as a secondary component, and has a coefficient of thermal conductivity of 17 to 30 W/m-K, wherein the Ni alloy contains Cr in an amount greater than that of Fe.

A spark plug comprising:

• a center electrode having an outer circumferential surface;
• an insulator surrounding the center electrode;
• and
• a ground electrode positioned relative to a tip end portion of the insulator and a tip end portion of the center electrode such that a spark discharge gap is formed between the ground electrode and the tip end portion of the center electrode, and creeping spark discharge along a surface of the tip end portion of the insulator can occur at the spark discharge gap, wherein
• an electrode base material which forms at least a surface layer portion of the center electrode is made of an Ni alloy having a coefficient of thermal conductivity of 17 to 30 W/m-K, the Ni alloy containing Ni as a predominant component and an element, as a secondary component, which element can form an oxide semiconductor having a resistivity of negative temperature coefficient, wherein a consumption-resistant portion is formed on the outer circumferential surface of the center electrode, and the consumption-resistant portion is formed so as not to cross regions corresponding to the tip end of the insulator with respect to the axis of the center electrode.

A spark plug comprising:

• a center electrode having an outer circumferential surface;
• an insulator having a through hole surrounding the center electrode;
• and
• a ground electrode positioned relative to a tip end portion of the insulator and a tip end portion of the center electrode such that a spark discharge gap is formed between the ground electrode and the tip end portion of the center electrode, and creeping spark dischrge along a surface of the tip end portion of the insulator can occur at the spark discharge gap, wherein
• an electrode base material which forms at least a surface layer portion of the center electrode is made of an Ni alloy having a coefficient of thermal conductivity of 17 to 30 W/m-K, the Ni alloy containing Ni as a predominant component and an element, as a secondary component, which element can form an oxide semiconductor having a resistivity of negative temperature coefficient, wherein a consumption-resistant portion is formed on the outer circumferential surface of the center electrode, and the whole consumption-resistant portion is accommodated in the through hole of the insulator.