Platinum-coated igniters

Claim 2

An igniter comprising two or more electrodes separated by a body of insulating or semi-conducting material and having exposed working surfaces between which sparks may pass, at least part of the working surface or surfaces of at least one of the electrodes comprising a host material in which Co or Ni predominates alloyed or compounded with one or more additional metals selected from the group consisting of Ru, Rh, Ir, Pt, Ag and Au.

Claim 3

An igniter according to claim 1, wherein the additional metal or metals constitute from a trace to 20 wt.% of the total metal content.

Claim 4

An igniter according to claim 1, wherein the most material is an alloy comprising 20 wt.% Cr, 0.4 wt.% Ti, 0.1 wt.% Mn, 0.7 wt.% Si, 0.01 wt.% C and balance nickel and wherein from a trace to 20 wt.% of the nickel content is replaced by one or more of the additional metals.

Claim 5

An igniter according to claim 3, wherein the additional metal is Pt.

Claim 6

An igniter according to claim 4, wherein Pt is present in an amount from a trace to 10 wt.% of the total metal content.

Claim 7

An igniter according to claim 1, wherein the host material is an alloy comprising 9.0 wt.% Cr, 10 wt.% Co, 12 wt.% W, 1.0 wt.% Nb, 5.0 wt.% Al, 2.0 wt.% Ti, 0.15 wt.% C, 0.015 wt.% B, 0.05 wt.% Zr and balance nickel, and wherein from a trace to 20 wt.% of the nickel is replaced by one or more of the additional metals.

Claim 8

An igniter according to claim 6, wherein the additional metal is Pt.

Claim 9

An igniter according to claim 7, wherein Pt is present in an amount from a trace to 10 wt.% of the total metal content.

Claim 10

An igniter according to claim 1, wherein the host material is an alloy comprising 40 to 98 wt.% nickel and a trace to 30 wt.% chromium and wherein the additional metal or metals constitute from a trace to 15 wt.% of the total metal content.

Claim 11

An igniter according to claim 9, wherein the host material contains from 54 to 78 wt.% Ni and from 13 to 25 wt.% Cr and wherein the additional metal or metals constitute from 5 to 15 wt.% of the total metal content.

Claim 12

An igniter according to claim 9, wherein the host material contains at least 40 wt.% Ni and from a trace to the percentage specified of any one or more of the following components: ______________________________________ cobalt 25 wt.% titanium 6 wt.% aluminium 7 wt. tungsten 20 wt.% molybdenum 20 wt.% hafnium 2 wt.% manganese 2 wt.% silicon 1.5 wt.% vanadium 2.0 wt.% niobium 5 wt.% boron 0.15 wt.% carbon 0.05 wt.% tantalum 10 wt.% zirconium 3 wt.% iron 20 wt.% thorium/rare earth metals or oxides thereof 3 wt.%. ______________________________________

Claim 13

An igniter according to claim 11, wherein the additional metal is platinum present in an amount from a trace to 15 wt.% of the total metal content.

Claim 14

An igniter according to claim 10, wherein the host material contains at least 40 wt.% Ni and from a trace to the percentage specified of any one or more of the following components: ______________________________________ cobalt 25 wt.% titanium 6 wt.% aluminum 7 wt.% tungsten 20 wt.% molybdenum 20 wt.% hafnium 2 wt.% manganese 2 wt.% silicon 1.5 wt.% vanadium 2.0 wt.% niobium 5 wt.% boron 0.15 wt.% carbon 0.05 wt.% tantalum 10 wt.% zirconium 3 wt.% iron 20 wt.% thorium/rare earth metals or oxides thereof 3 wt.%. ______________________________________

Claim 15

An igniter according to claim 13, wherein the additional metal is platinum present in an amount from a trace to 15 wt.% of the total metal content.

Claim 16

An igniter according to claim 1, wherein the host material is an alloy comprising not less than 40 wt.% Co and a trace up to 30 wt.% chromium and wherein the additional metal or metals constitute from a trace to 15 wt.% of the total metal content.

Claim 17

An igniter according to claim 15, wherein the additional metal is platinum present in an amount from a trace to 15 wt.% of the total metal content.

Claim 18

An igniter according to claim 15, wherein the host material contains not less than 40 wt.% Co and from 13 to 25 wt.% chromium, and wherein the additional metal or metals constitute from 5 to 15 wt.% of the total metal content.

Claim 19

An igniter according to claim 17, wherein the additional metal is platinum present in an amount from a trace to 15 wt.% of the total metal content.

Claim 20

An igniter according to claim 17, wherein the most material contains at least 40 wt.% cobalt and from a trace to the percentage specified of any one or more of the following components: ______________________________________ nickel 25 wt.% titanium 2 wt.% aluminium 5 wt. tungsten 30 wt.% molybdenum 5 wt.% iron 5 wt.% tantalum 10 wt.% niobium 5 wt.% manganese 2 wt.% silicon 1 wt.% carbon 1 wt.% boron 0.05 wt.% zirconium 1.5 wt.% rhenium 3 wt.% thorium/rare earth metals or oxides thereof 5 wt.%. ______________________________________

Claim 21

An igniter according to claim 19, wherein the additional metal is platinum present in an amount from a trace to 15 wt.% of the total metal content.

Claim 22

An igniter according to claim 1, wherein the said additional metal or metals constitute a surface layer on a substrate constituted by the host material.

Claim 23

An igniter according to claim 21, wherein the surface layer is diffusion bonded to the substrate of the host material.

Claim 24

An igniter according to claim 1, wherein the insulating or semi-conducting material is selected from the group consisting of refractory oxides, ceramics, glasses, carbides, borides, nitrides and silicides.

Claim 25

An igniter comprising two or more electrodes separated by a body of insulating or semi-conducting material and having exposed working surfaces between which sparks may pass, at least part of the working surface of an electrode comprising a dispersion-strengthened platinum group metal or platinum group metal alloy; thoriated tungsten platinum; a cermet; a composite material comprising a skeleton of sintered platinum group metal particles, Ag or Au into which is infiltrated a Cu/Ni alloy; or an Ag/Pt alloy loaded with particles of one or more platinum group metals, platinum group metal alloys, silver or gold.

Claim 26

An igniter comprising two or more electrodes separated by a body of insulating or semi-conducting material and having exposed working surfaces between which sparks may pass, at least part of the working surface of an electrode comprising a dispersion-strengthened platinum group metal or platinum group metal alloy; thoriated tungsten platinum; a cermet; a composite material comprising a skeleton of sintered platinum group metal particles, Ag or Au into which is infiltrated a Cu/Ni alloy; or an Ag/Pt alloy loaded with particles of one or more platinum group metals, platinum group metal alloys, silver or gold.