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Journal Archive

Platinum Metals Rev., 1974, 18, (3), 115

NEW PATENTS: July 1974



Tarnish Resistant Alloy

pennwalt corp. U.S. Patent 3,767,391

A tarnish-resistant alloy, especially useful in the presence of S and S-containing environments, contains 39−47% Au, 9−12% Pd and the balance Ag and Cu with a Ag:Cu ratio of 1:1 to 1.5:1.

Radioisotopic Heat Source

u.s. atomic energy commission U.S. Patent 3,767,930

A radioisotopic heat source includes a core of heat-productive, radioisotopic material, an impactresistant layer of graphite surrounding the core and a shell of Ir metal between the core and the impact layer.

Bright Cast Alloy

williams gold refining co. U.S. Patent 3,769,006

An improved Au alloy casting composition has sufficient Al and/or Si to form a lustrous oxidationresistant surface coating during and after casting. Typically 0.08−0.32% Al is added to a Au dental alloy containing 3% Pd, 8% Pt, <1% In and Sn and 0.25% Fe.


Organic Palladium Compounds in Organic Synthesis

hercules inc. U.S. Patent 3,783,140

An organic group is introduced into an ethylenically unsaturated carboxylic acid using an organic Pd complex formed in situ . In an example, a mixture of phenyl mercuric chloride, Li Pd chloride and acrylic acid is formed in acetonitrile as solvent. This results in the formation of an unstable adduct between the acrylic acid and phenyl Pd chloride.


Rhodium and Molybdenum Mixed Oxide

solvay et cie. U.S. Patent 3,773,915

An oxidic compound of Rh and Mo of empirical formula Rh2MoO6, having semiconducting properties, is suitable for coating electrodes.


Rhodium Plating Bath

american chemical & refining co. inc. British Patent 1,346,753

A bright deposit of improved properties is obtained from a bath containing 1.0−30 g/l Rh ions, 0.05−5.0 g/l Al ions, 50−400 g/l sulphamic acid and 1.0−25 g/l of a polybasic organic carboxylic acid.

Chemical Plating Sensitiser

rca corp. British Patent 1,348,793

The chemical deposition of Pt, Pd, Au, Co, Cu, Ni, etc., on non-conducting surfaces, such as plastics materials, may be sensitised by treatment with a solution containing both divalent and tetravalent tin ions. In one example a solution of SnCl2 and SnCl4 is used to treat a plastics surface before a Pd catalyst for chemical Ni plating is deposited.

Chemical Plating of Polypropylene

diamond shamrock corp. British Patent 1,348,842

In order to enable polypropylene to be plated using a conventional SnCl2−PdCl2 pretreatment, a small amount of a phenolic compound and/or resin compound is added.

Sensitising for Chemical Plating

kollmorgen corp. British Patent 1,349,666

A solid sensitising composition that readily dissolves to a clear solution contains a Pt group metal, a Group IV metal and an anion capable of forming a stable compound with both valencies of the Group IV metal. The ratio of the three components varies from 1:1:3 to 1:6:24. The preferred metals are Pd and Sn.

Undercoat for Rhodium Plating

ampex corp. U.S. Patent 3,767,369

Rh-plated articles are given superior wear qualities by providing an undercoating of a Sn-Ni alloy. The undercoat is particularly applicable for metallic discs having a magnetic coating used for data or TV recording. The amount of Rh used may also be reduced.

Deposition of Metals or Oxides on a Metallic Support by Cathodic Sputtering

progil U.S. Patent 3,773,639

A precious metal or its oxide is deposited on a metallic support by first submitting the metallic support to ionic bombardment in a rare gas atmosphere, then, without cooling below 300°C, depositing the precious metal by cathodic sputtering conducted first in a rare gas atmosphere and then in an atmosphere of mixed O2 and rare gas. Pt can be deposited on Ti in this way to provide electrolysis electrodes.

Selectively Depositing a Metal on a Substrate

western electric co. U.S. Patent 3,775,121

Selective chemical plating is achieved by sensitising the substrate surface and depositing an activator such as Pd. The activator is poisoned to destroy its activity. UV radiation through a mask or image is used to reactivate the activator only in selected areas. The activator is available to bring about chemical plating of those areas.

Electrodeposition of Rhodium

bell telephone laboratories inc. U.S. Patent 3,775,267

Plating with a soluble Rh electrode is achieved by maintaining a constant Rh concentration in the electrolyte, the continuous dissolution of the Rh anode being effected by imposing a pulsed signal on to it.


Titanium Brazing Alloy

alloy metals inc. U.S. Patent 3,778,258

A strong, ductile, corrosion-resistant alloy suitable for brazing Ti and Ti-based alloys contains about 3−30% Al, about 3−17% Pd and about 55−95% Ag.

Platinum-based Weldable Material

comptoir lyon-alemand-louyot French Patent 2,171,659

A Pt-based welding material comprises PtO2 and 0.005−0.2% (based on the PtO2) of Y; it may also contain at least one lanthanide oxide.


Catalytic Composite

universal oil products co. British Patent 1,345,611

A complex catalyst for hydrocarbon conversion is produced by dissolving GeCl4 in an anhydrous alcohol, equilibriating the solution and mixing it with an aqueous Pt metal solution. The product is used to impregnate a porous support, e.g. γ-Al2O3. After firing, the support should contain 0.01−5% Ge, 0.01−2% Pt group metal and 0.5−4% Cl2. Pt itself is preferred.

Dehydrogenation Catalyst

univlrsal oil products co. British Patent 1,345,612

A dehydrogenation catalyst is formed by mixing an alcoholic Ge tetrahalide solution with aqueous solutions of a Pt group metal compound and an alkali metal compound. The mixture is used to impregnate a porous support such as Al2O3. Preferably the catalyst after calcining contains 0.05−5% Ge, 0.05−5% Pt and 0.01−1.5% Li.

Hydrogenation of Hydrocarbon Resins

eastman kodak co. British Patent 1,345,619

Petroleum resins produced by the polymerisation of unsaturated feedstocks over metal chorides are improved by hydrogenation, preferably in the presence of a Pd catalyst.

Hydrogen Cyanide Production

e.i. du pont de nemours & co. British Patent 1,345,785

HCN is produced in the vapour phase by the reaction of O2, NH3 and a hydrocarbon over a Pt group metal catalyst, especially a gauze made from an alloy of Pt with up to 20% Rh.

Platinum Metal Catalysts

shell internationale research mij. n.v. British Patent 1,348,653

Where Sn accompanies Pt (or another Pt group metal) in a supported hydrocarbon conversion catalyst, a more active catalyst is produced when the Sn is supplied to the support as a stannate ion. For example Al2O3 may be impregnated using a Pt salt solution and a Na stannate solution.

Acetic Acid Production

national distillers & chemical corp. British Patent 1,349,100

C2H4 is oxidised to CH3COOH in the presence of added H2O and a supported catalyst containing Pd metal and H3PO4. Al2O3 and C supports are mentioned in the examples and they carry 0.01−5% Pd and at least 2% H3PO4.

Ruthenium Catalyst

diamond shamrock corp. U.S. Patent 3,766,089

An improved Ru catalyst is prepared by impregnating a catalyst support with a RuCl3 solution, drying the impregnated support and then partially reducing the dried RuCl3 coating on the support. The catalyst is useful in the hydrogenation of the pyrroles. Spent catalyst can be rejuvenated by recoating with RuCl3 solution, drying the coated spent catalyst and then partially reducing the RuCl3 coating.

Auto Emission Catalyst

air products & chemicals inc. U.S. Patent 3,770,659

The active catalyst for burning exhaust gases from an internal combustion engine consists essentially of a sorptive Al2O3 matrix, 5−18% MnO, 2−8% Cr2O3 and 0.01−0.2% Pd, the unit weight ratio of MnO to Cr2O3 being 2−3.5 and the total weight of such oxides being 8−24%.

Preparation of a Catalytic Composite

universal oil products co. U.S. Patent 3,772,213

A Pt group component and a Ge component are uniformly dispersed throughout a porous high surface area carrier material by treating a GeCl4/anhydrous alcohol solution with an aqueous solution of a H2O-soluble, decomposable compound of a Pt group metal and using this as the impregnation solution.

Hydrocarbon Isomerisation Process

universal oil products co. U.S. Patent 3,772,397

Hydrocarbons are isomerised using a catalytic composite comprising a combination of a Pt group component and a Sn component with a porous carrier material, e.g. 0.75% Pt and 0.5% Sn on γ-Al2O3.

Hydrocracking Process

sun oil co. of pennsylvania U.S. Patent 3,775,297

Fresh gas oils are converted to high quality motor fuels and naphthenic lubricating oils by hydrocracking at 720−750°C in the presence of crystalline zeolite hydrocracking catalyst containing a hydrogenating component, e.g. Pd, the catalyst having been preconditioned to a predetermined state of deactivation. Preconditioning is accomplished by accelerated coking with an aromatic gas oil at 800−900°F. The preferred catalyst consists of 0.1−1% Pd on a Y-zeolite.

Hydrocarbon Conversion with a Catalytic Composite of Platinum, Iron and Germanium

universal oil products co. U.S. Patent 3,775,300

Hydrocarbons are converted by contacting them with a catalytic composite of a Pt group metal component, an Fe component and a Group IVA metallic component with a porous carrier material, e.g. 0.375% Pt, 0.5% Ge and 0.1% Fe on Al2O3 containing 0.85% Cl2.

Hydrocarbon Conversion with a Trimetallic Catalytic Composite

universal oil products co. U.S. Patent 3,775,301

Hydrocarbons are converted by contacting them with a combination of a Pt group metal component, a Re component and a Ge component with a porous carrier material, e.g. 0.1% Re 0.2% Ge and 0.5% Pt on Al2O3 containing 0.85% Cl2.

Dehydrocyclisation of Paraffins

sun research & development co. U.S. Patent 3,775,502

A Na zeolite X or Na zeolite Y, is ion-exchanged with from 0.10−1.2% Pt. The catalyst is calcined and the Pt then reduced with H2 to the free metal to catalyse the dehydrocyclisation of 6−10C paraffins.

Reforming Catalyst

cities service oil co. U.S. Patent 3,776,860

An improved reforming catalyst has an Al2O3 support impregnated with Pt, Re and a rare earth metal. Preferably the catalyst composition comprises Pt, Re and rare earth metals such as Nd, Pz, Sm and Yb each in amounts of from 0.1−5%.

Platinum and Lead Catalyst

asahi kasei k.k.k. U.S. Patent 3,781,221

Selective reforming catalysts contain an Al2O3 carrier, with pores of a diameter distribution having a peak in the range of 2,000−7,000Å supporting Pt and Pb. The pores are obtained by burning out an organic material used in shaping the catalyst support.

Hydrocarbon Conversion Catalyst

ste. francaise des produits pour catalyse French Patent 2,164,986

A hydrocarbon conversion catalyst consists of an Al2O3-supported mixture of Pt, Ir and Sc, Y, Ac, Ti, Zr, Hf, Th, Ge, Sn or Pb, e.g. 0.2% Pt, 0.05% Ir and 0.5% Th. In French Patent 2,165,056 the third element is 0.5% of U, Pa, Ga, V, or Tc.

Carbon Catalyst Supports

ste. rhone-progil French Patent 2,165,280

Active C is treated with an aqueous solution of a volatile acid, e.g. HCl, and dried before treatment with a mineral base such as NaOH. This dual treatment is said to improve the catalyst support properties. In one example this support is impregnated with RhCl[P(OPh)3]3.


johnson, matthey & co. ltd. German Offen. 2,229,210

A catalyst for the treatment of exhaust gases and for production of CH4 by the steam reforming of naphtha comprises a refractory support coated with a first layer of one or more oxides of Ti, Zr, Hf and Th and a final layer of a mixture or alloy of Pt, Rh (1−50%) and optionally base metal (0.01−25%). Preferably the base metal is Ni or Cu and the final coating contains 0.01−10% by weight of the total metal content.

Dehalogenation Catalysts

knapsack a.g. German Offen. 2,240,466

The dehalogenation of organic compounds, especially the dechlorination of polychloroacetic acids, is catalysed by a supported Pd catalyst in which the Pd is enriched on the surface.

Zeolitic Catalyst

shell internationale research mij. n.v. Dutch Appln. 72. 11,593

Catalysts for selective hydrocracking and other reactions are prepared by a specified system of heat treatment of a cation-exchanged zeolite, such as KS 01, on which a metal, such as Pd, Pt, Ru and Rh (among others), is deposited.

Ketone Production Catalyst

shell internationale research mij. n.v. Dutch Appln. 72. 11,914

Ketones are produced by the reaction of mercaptans with H2O in the presence of a supported Group VB, VIB and/or Mn sulphide catalyst promoted by a Group VIII metal such as Rh or Ir. In one example butanethiol–2 is converted to butanone–2 in the presence of a sulphided mixture of Mo and Rh on Al2O3.


Olefin Production

imperial chemical industries ltd. British Patent 1,344,887 British Patent 1,278,806 describes a process in which 1,6- and/or 1,7-octadienes are produced by contacting one or more acyclic conjugated dienes with metallic Pt, Pd, Rh, Ru, or Os in a polar solvent. It has now been found that the process may also be carried out in a non-polar solvent such as C6H6.

Adipic Acid Production

badische anilin- & soda-fabrik a.g. British Patent 1,348,800

Butadiene is reacted with CO and H2O to give adipic acid in the presence of a Rh catalyst activated with an organic halide in the absence of acid. Thus Rh(CO)2Cl can be used in the presence of CH3I (used in all the four examples).

Silicon Rubber Production

general electric co. British Patent 1,349,311

New Si rubbers are produced from silyl isocyanurates in whose production Pt catalysts may be used for the silylation reaction.

Platinum Complexes of Unsaturated Siloxanes

general electric co. U.S. Patent 3,755,452

Pt complexes of unsaturated siloxanes are provided which are useful as hydrosilation catalysts. These Pt-siloxane complexes can contain an average of up to ∼1 g.atom of halogen per g. atom of Pt, but include complexes which are substantially free of inorganic halogen.

Production of Alcohols

union oil co. of california U.S. Patent 3,766,279

Aldehydes are converted to higher molecular weight alcohols by simultaneous aldol condensation and hydrogenation reactions which are catalysed by a Ru-biphyllic ligand catalyst, e.g. RuCl3(PPh3)3.

Activator Solutions for Electroless Plating

enthone inc. U.S. Patent 3,767,583

Surfaces intended to be electrolessly metal plated are treated with a colloidal catalyst metal-free acid liquid solution of a soluble, Lewis base-modified noble metal-Sn halide complex until the surface becomes catalytic, e.g. a PdCl2-SnCl2-CH3OH complex.

Alcohol Amine Interchange

union oil co. of california U.S. Patent 3,767,709

A tertiary amine is reacted with an alcohol or aldehyde in a liquid reaction medium containing a Ru, Os, Re, or Tc catalyst which is preferably in complex association with a biphyllic ligand to interchange the hydrocarbyl portions of the reactants. In a typical process tributylamine is contacted with octanol in the presence of RuCl3 and Ph3P to produce butanol and octyl dibutylamine. Aldehydes can be similarly reacted under H2 pressure.

Oxidation of α-Aryl Alcohols

union oil co. of california U.S. Patent 3,769,325

Aryl alcohols or their ethers are oxidised to aldehydes, ketones or esters using Group VIII arsine, phosphine, stibine or bismuthine complexes, e.g. a RhCl3 or PdCl3-Ph3P complex.

Redox Catalyst System for Ethylene-Vinyl Grafted Copolymer Dispersions

wacker-chemie g.m.b.h. U.S. Patent 3,773,699

K persulphate, a Pd salt and ammonium ferric sulphate are used as a redox system for graft copolymerising EVA emulsions with vinyl chloride or another monomer.

Process for Benzyl Ketones

standard oil co. U.S. Patent 3,773,837

Benzyl ketones are produced in a one-step process by reacting C6H6 with a ketone at elevated temperatures in the presence of a divalent Pd salt of a carboxylic acid and a strongly acidic catalyst.

Preparation of Unsaturated Esters

esso research & engineering co. U.S. Patent 3,775,469

Unsaturated esters are prepared through the reaction of a 4−6C aliphatic conjugated diene with a carboxylic acid in the presence of a Pd catalyst, or organic phosphine or phosphite ligand modifier and a promotor compound such as NaBH4 or acetic anhydride. The reaction is carried out in the absence of tertiary amines and in the substantial absence of O2. Pd acetylacetonate is used in the examples.

Platinum or Palladium Phosphinite Catalysts

e. i. du pont de nemours & co. U.S. Patent 3,776,929

Compounds of formula (L)2MXY, where L is a phosphinite, phosphonite, thiophosphinite or dithiophosphonite ligand, M is Pd or Pt, and X and Y are alike or different and are selected from Cl, Br, I, various substituted and unsubstituted alkyls and aryls, cyano, SnCl3, isocyanate, thiocyanate, aroyl, and lower perfluoroalkyl groups are produced by reacting one equivalent of a source of MXY with two or more equivalents of a selected P-containing ligand. The products, e.g. PtCl2-(dimethyl phenyl phosphinite) are useful in the alkoxycarbonylation of olefins and in the polymerisation of acetylene.

Preparation of Alkadienoic Acid Esters

esso research & engineering co. U.S. Patent 3,780,074

Esters of alkadienoic acids are prepared through the reaction of 4−12C aliphatic, acyclic, conjugated diolefins with a 1−20C monohydroxy alcohol and either gaseous CO or gases containing CO in the presence of a catalyst system including zerovalent Pd, e.g. Pd(PPh3)4.

Synthesis of Pyridine Bases

yawata chemical industry co. ltd. U.S. Patent 3,781,292

Pyridine bases are produced by reacting olefins with NH3 in the presence of a Pd tetrammine complex whose activity is enhanced by means of a Cu (II) salt and O2. Thus PdCl2, NH3 and CuCl2 may be used in picoline production.

Preparation of Aromatic Isocyanates

olin corp. U.S. Patent 3,781,321

The complex PdL(CO)X2, where L is a heterocyclic N compound such as lutidine and where X is a halogen, is prepared by reacting CO with a Lewis base and a Pd dihalide and/or a mixture of elementary Pd with an acid halide, in the presence of a liquid reaction medium. The resulting complex is useful as a catalyst in the preparation of organic isocyanates by reacting CO with an organic nitro compound.

Preparation of α-Hydroxyamides

union oil co. of california U.S. Patent 3,781,351

Formamide or a substituted formamide is reacted with a 2−12C carbonyl compound in a liquid reaction medium containing a Ru or Os catalyst, preferably complexed with a biphyllic ligand, at 50−300°C to form an α-hydroxyamide. In a typical process formamide is reacted with an excess of benzaldehyde in the liquid phase in the presence of RuCl3 complexed with triphenyl phosphine to produce alpha-hydroxyphenyl acetamide.


Fuel Cell Electrode

united aircraft corp. U.S. Patent 3,755,947

A fuel cell electrode has an anodic catalyst including Pt and Rh oxides and a Ni, Co, Fe, or Cu oxide together with a component convertible to W oxide to provide high electrical performance at very low noble metal loadings. A typical mixture of oxides contains 2g Pt, 0.1g Rh and 1.9g Ni.

Fuel Cell Electrode

studiecentrum voor kernenergie Dutch Appln. 72.14,900

A fuel cell electrode has an electrically conducting metal grid with a catalyst-containing coating which has one or more layers varying in porosity. The catalyst layer, for example, consists of ptfe particles forming a matrix containing Pd, Pt or Ag catalyst.


Preparing Radiation Source Material

u.s. atomic energy commission U.S. Patent 3,773,295

A uniform dispersion of a radioisotope within a noble metal matrix is provided by chemically plating a noble metal coating on to particles including a dissociable compound of the radioisotope. For example, Pd in the presence of H2 can be deposited on Cf oxalate particles containing Cf-252. The coated particles are dried and the oxalate decomposed to Cf oxide.

Diffusion Cell

johnson, matthey & co. ltd. U.S. Patent 3,782,077

A H2 diffusion unit for separating mixtures from gaeous mixtures containing H2 has two superimposed metal foils such as Ag/Pd foils, bonded together at their edges to form an envelope. At least one of the foils is corrugated or undulated and each corrugation or undulation is supported by a helix of stainless steel or like wire.

Fogged, Direct-positive Silver Halide Emulsion Layer

fuju photo film co. ltd. U.S. Patent 3,782,957

Pt group metal compounds such as K3RuCl6 are used with methine dyes in photographic sensitisation.


Glass Feeders

owens-corning fiber-glass corp. British Patent 1,350,644

New alloys for glass feeders consist of 14−85% Pt, 15−85% Rh and 0.1−1% of an additional metal selected from Mo, W, Ir, and Re in an amount only sufficient to increase the ductility of the alloy.

Alloy Glass Fibre Forming Bushing

j. h. hansen & r. w. betz U.S. Patent 3,779,728

A high temperature-high strength alloy containing Pt, Rh and one or more of Mo, W, Ir, and Re is fabricated into apparatus adapted to receive and controllably emit molten material for attenuation into glass fibres. One example of the alloy contains 79% Pt, 20.99% Rh and 0.01% Mo.



owens-illinois inc. British Patent 1,345,549

PdO and related metal oxide resistors are very sensitive to firing schedules and their stability is low. These problems are now overcome by the use of metallising compositions which contain an organic Pd, Rh, Ir, Ru, or In compound.

Electrically-insulating Seal between a Metal Body and a Semiconductor Device

r.c.a. corp. U.S. Patent 3,769,688

A seal is built up by oxidising the surface of the semiconductor, depositing a layer of Si, evaporating Pd on to the Si and finally covering the Pd with W, Ni and a solder.

Printed Dielectric/Palladium-Silver Structures

e. i. du pont de nemours & co. U.S. Patent 3,770,496

In a method for printing multilayer electronic structures on a substrate which minimises degradation at crossovers, at least 20% Ag is incorporated in the metallisation used to print the Au electrode which is used with dielectric crossovers and a Ag or Ag/Pd electrode.

Electrical Resistance Compositions

shoei chemical industries co. ltd. U.S. Patent 3,776,772

An electrical resistance composition comprises particles of RuO2 coated with Nb and/or Nb oxide and a glass frit. In one example the composition contains RuO2/Nb particles (12 parts) with 63 parts glass frit and 25 parts alkyd resin solution.

Electro-conductive Material and RuO2

murata manufacturing co. ltd. U.S. Patent 3,778,389

An electro-conductive material, essentially consisting of a double oxide obtained from PbO and RuO2 in a molar ratio of 3:1 to 1:3, is useful as the fundamental composition for production of a resistor paste, a ceramic resistor or the like.

Tungsten Electrical Switching Contacts

echlin manufacturing corp. U.S. Patent 3,778,576

The contacts consist of a porous body, obtained by leaching Fe from a W, Mo, Re, or Nb alloy, plated with a thin layer of Au, Ag, Pt, Pd, or Rh and then with Ni or Co.

Method of Platinum Diffusion in Semiconductors

t.r.w. inc. U.S. Patent 3,783,049

A controlled degradation of minority carrier lifetime in a Si semi-conductor crystal body uses H2Pt(OH)6 as a source of Pt. One gram of H2Pt(OH)6 is dissolved in 130 cm2 anhydrous acetone and approximately 0.05 cm2 of this solution is placed on the surface of a Si semiconductor crystal body. The solution is dried and the body is then heated to the Pt diffusion temperature for a time sufficient to have Pt atoms uniformly distributed throughout the active portion of the Si crystal.

Process for Making Capacitors

e.i. du pont de nemours & co. U.S. Patent 3,784,887

An improved process for making multilayer monolithic capacitors uses metallised areas which can be cofired with reactive dielectric materials at elevated temperatures. The metallisation materials contain critical proportionate amounts of Pt and/or Au and Pd and optionally Ag.

Resistance Pastes

deutsche gold- & silber-scheideanstalt German Offen. 2,234,543

Pd, Ru and other noble metal sulphides are used as semiconducting constituents in resistance pastes. Noble metal or metal alloy powders may also be present. In an example PdS is used with B oxides, red Pb, SiO2, and ZnO to form a frit used in screen printing compositions.

Resistance Pastes

deutsche gold- & silber-scheideanstalt German Offen. 2,234,644

Pastes for the production of fired electrical resistances are based on the use, as conductor, of semiconducting mixed crystals of PdO and CuO, optionally accompanied by a noble metal powder, e.g. a Ag-Pd alloy powder.



general electric co. U.S. Patent 3,766,511

Thermistors are provided in which the thermally sensitive semiconducting material has the formula PbO.PdZO4, where Z is selected from Cr, Mo, W, and S. The thermistor device can be made by dipping two closely spaced electrical conductors into a melt of the thermally sensitive semiconducting material to form an element of the material between the conductors.

Resistance Thermometer Element

johnson, matthey & co. ltd. U.S. Patent 3,781,749

A temperature-sensitive element is made from a layer of glass containing conducting particles attached to a non-conducting support. Au, Ag, Pt metals, Fe, Ni, Co, or Cu may form the particles.