Abstract: The present invention relates to electrically conductive potentially adhesive compositions and to films formed from these compositions which are capable of being employed in particular for the adhesive bonding of the surfaces of electronic devices.These compositions are characterized in that they comprise a thermoplastic polyblock organopolysiloxane copolymer with elastomeric properties and particles whose surface at least is electrically conductive and, if appropriate, a solvent or diluent.

Abstract: The present invention relates to electrically conductive, potentially adhesive compositions and to films formed from these compositions which are capable of being employed in particular for the adhesive bonding of the surfaces of electronic devices.These compositions are characterized in that they comprise a thermoplastic block copolymer containing polysiloxane and urethane groups, with elastomeric properties and particles whose surface at least is electrically conductive and, if appropriate, a solvent or diluent.

Abstract: A coherent particulate composite is formed by blending particulate material with a binder containing lignosulfonate and urea.

Abstract: A binder/suspension liquid for use with refractory compounds and the like. Oxidation prevention coatings for up to at least 1000 degrees Centigrade are described. Both a graphite non-conductive and a conductive coating are described for use in coating graphite crucibles, graphite electrodes, and the like. Typical compositions utilize a binder/suspension liquid phase in an amount from about 40 to about 55 wt. % of the total paintable mixture. This binder/suspension liquid phase is formed by intimately mixing colloidal silica solution, mono-aluminum phosphate solution and alcohol. The non-conducting embodiment of the graphite coating is produced by mixing finely divided boric acid and silicon carbide with the binder/suspension liquid phase. The preferred conductive coating substitutes a mixed TiC-SiC for the SiC of the non-conductive embodiment. The resultant material is very stable (i.e., does not settle), is paintable upon the graphite, and is easily dried at or near room temperature.

Abstract: A silicon carbide sintered body suitable for electrical discharge machining and a method for its manufacture are disclosed. The silicon carbide sintered body comprises 0.5-5% by weight of AlN, 0.5-3% by weight (as Ti) of a Ti compound, 0.5-8% by weight of C, 0-3% by weight (as B) of B or a B compound, and a remainder of substantially SiC. It has a volume resistivity at room temperature of not greater than 10 ohm-cm and a density of at least 90% of the theoretical density of SiC. The manufacturing method comprises shaping a mixture of the raw materials and sintering the shaped green body in a non-oxidizing atmosphere at a temperature of 2000.degree.-2300.degree. C.

Abstract: Electrically and/or thermally conductive reinforced compositions convertible to reinforced components are disclosed. The compositions comprise a polymeric material of little or no conductivity and high strength, metal plated composite fibers having a conductive semimetallic core and a thin, firmly adhered layer of an electrodepositable metal coating on said core. The metal coated composite fibers will not lose their conductive coatings during normal processing and provide conductivity without reducing the physical properties of the polymeric material. The compositions of the invention are convertible to conductive components such as laminate prepregs, surface plys for laminates, conductive adhesives, conductive inks, and conductive elastomeric gaskets. The components can be incorporated in improved articles such as structural parts for transportation vehicles, printed circuit boards, lighting shields and molded articles.

Abstract: A low viscosity, electrically conductive ferrofluid composition and method of making and using same, which composition comprises: a first polar liquid carrier; a second polar liquid carrier miscible in the first polar carrier and comprising a polyol, such as a tetraethylene glycol dimethyl ether; magnetic particles to impart magnetic characteristics to the ferrofluid composition; and a surfactant, particularly a cationic surfactant in an amount sufficient to stabilize and disperse the magnetic particles, the surfactant dissociated or ionized predominately by the second polar liquid carrier.

Abstract: A polymer composition having positive temperature coefficient characteristics is described, comprising 100 parts by weight of a mixture consisting of from 40 to 90% by weight of a crystalline polymer and from 60 to 10% by weight of an electrically conductive powder and from 10 to 300 parts by weight of a semiconductive inorganic substance. This polymer composition can withstand high voltage and when used as a heat generator, produces a uniform distribution of heat and has a long service life. Thus the polymer composition is useful for production of an overcurrent protecting element and a heat generator.

Abstract: A ferrophosphorus composition with improved conductivity and passivation resistance is prepared by treating ferrophosphorus particles with an aqueous solution containing a dilute mineral acid and ions of chromium and a metal selected from the group consisting of zinc, strontium, calcium, barium, lead or copper. In a preferred embodiment, the concentration of chromium and zinc ions in the solution is in the range of about 2 grams/liter to about 10 grams/liter, and the treatment time is from about 2 to about 6 minutes.The treated ferrophosphorus particles can be formulated in a suitable resin binder for use as corrosion resistant coatings, weldable coatings, EMI shielding coatings or electrically conductive coatings. The treated ferrophosphorus particles can also be used in powder metallurgy applications.

Abstract: A material provides protection against electrical overstress transients having rise times as rapid as a few nanoseconds or less. The material comprises a matrix formed of a mixture of separate particles of conductive materials and separate particles of semiconductor materials coated with insulating material to provide chains of the particles within the matrix with interparticle separation distances along the chains less than several hundred angstroms, thereby to permit quantum-mechanical tunneling of electrons between the separate particles in response to high energy electrical transients.

Abstract: Corrosive resistant, coated laminate consisting of metal substrate, anti-corrosive layer and paint layer, which is characterized by the fact that the anti-corrosive layer is formed by a composition containing, as essential components, at least one hexa-valent chromium containing chromium compound having a solubility of 20 to 10.sup.-5 and aqueous silica and/or aqueous resin as binder, and as optional component, a water soluble chromium compound having a solubility of more than 20, and the paint layer is free from chromium compound. The laminate is excellent, inter alia, in adhesion of coating and anti-corrosive property. The invention also provides a coated metal plate having excellent corrosion resistance and continuous spot weldability.

Abstract: A spark plug having an improved radio noise suppression effect and durability of the resistor. The resistor of the spark plug is made of a sintered material comprising by weight, 0.9-3.0% of one of TiN, TiC, WC, TiB.sub.2, ZrC, HfC, SiC, TaC, MoSi.sub.2 and mixtures thereof, 9-40% of fine glass powder having a larger grain size than that of said conductive material, not more than 20% of magnetic substance, and 60-90% of coarse glass powder having a larger grain size than that of the fine glass powder. The composition is free of elemental carbon.

Abstract: An oxidation prevention coating for graphite up to at least 1000 degrees Centigrade. Both a non-conductive and a conductive coating are described for use in coating graphite crucibles, graphite electrodes, and the like. All of the compositions utilize a binder/suspension liquid phase in an amount from about 40 to about 55 wt % of the total paintable mixture. This binder/suspension liquid phase is formed by intimately mixing colloidal silica solution, mono-aluminum phosphate solution and ethyl alcohol. The non-conducting embodiment of the invention is produced by mixing finely divided boric acid and silicon carbide with the binder/suspension liquid phase. The preferred conductive coating substitutes a mixed TiC-SiC for the SiC of the non-conductive embodiment. The resultant material is very stable (i.e., does not settle), is paintable upon the graphite, and is easily dried at or near room temperature. A few thin coats, with drying between applications, totaling only about 0.15 to about 0.

Abstract: A coherent particulate composite is formed by blending particulate material with a binder containing lignosulfonate and urea.

Abstract: An anisotropically electroconductive adhesive which is solid at room temperature, preferably, in the form of a film is prepared by dispersing conductive particles such as metal particles and the like in a thermoplastic insulating adhesive composition comprising an unvulcanized thermoplastic elastomer such as a styrene-based elastomer and a crosslinked synthetic rubber and/or thermoplastic elastomer as a vulcanizate derived from an unvulcanized synthetic rubber or thermoplastic elastomer using a vulcanizing agent such as organic peroxides. The conductive adhesive is useful in adhesively bonding, for example, two electronic circuit boards without disadvantages of instability of the electric resistance, inconvenience in the application and so on.

Abstract: An electrically conductive adhesive composition which provides electric conductivity between facing electrodes but maintains electric insulation in the lateral direction across the facing direction, said composition comprising (a) a nonconductive base resin and (b) electrically conductive particles incorporated and dispersed in the resin (a); wherein(I) said electrically conductive particles (b) are composed of(b-1) 10 to 75%, based on the total weight of the components (a), (b-1) and (b-2), of abrasive grain-like electrically conductive particles having an average particle diameter of at least 1 micrometer, and(b-2) 0.2 to 20% by weight, based on the total weight of the components (a), (b-1) and (b-2), of electrically conductive fine particles having an average particle diameter of not more than 0.5 micrometer, and(II) said electrically conductive adhesive composition contains a solvent for said base resin (a) in an amount required to form said composition into the state of a printing ink or a paint.

Abstract: An electrical contact comprises 5 to 20 weight percent tungsten carbide, 0.5 to 3 weight percent graphite, balance silver. The contact has low erosion rate, low contact resistance, and anti-welding properties.

Abstract: A low viscosity, electrically conductive ferrofluid composition and method of making and using same, which composition comprises: a first polar liquid carrier; a second polar liquid carrier miscible in the first polar carrier and comprising a polyol, such as a tetraethylene glycol dimethyl ether; magnetic particles to impart magnetic characteristics to the ferrofluid composition; and a surfactant, particularly a cationic surfactant in an amount sufficient to stabilize and disperse the magnetic particles, the surfactant dissociated or ionized predominately by the second polar liquid carrier.

Abstract: A soldering iron bit is heated by an electrical heating element including a resistive element consisting of granular boron carbide packed in a quartz tube embedded in a piece of copper. A first power lead is electrically connected to the boron carbide at one end of the quartz tube. This first power lead passes through and is electrically insulated from the piece of copper. The second power lead is electrically connected to the boron carbide at the other end of the quartz tube, either directly or via the piece of copper. In use, connection of the first and second leads to an electrical power source causes the resistive element to generate heat in a very fast manner and to transmit this heat to the piece of copper. The piece of copper may be connected to or constitute the soldering bit and can be provided with a built-in thermostat comprising a meltable salt inserted in a hole provided in the piece of copper.

Abstract: The invention is a polycrystalline sintered body based on lanthanum hexaboride and having a density of at least 95% of the theoretical density. The sintered body comprises lanthanum hexaboride, boron carbide and amorphous carbon, the content of B.sub.4 C+C being from 0.1 to 10% by weight and the total amount of La+B+C being at least 99.0% by weight, in each case calculated on the total weight. The sintered bodies have a homogeneous microstructure with mean grain sizes<10 .mu.m, in which, in addition to the crystalline lanthanum hexaboride phase, boron carbide and carbon are detectable as separate, finely divided phases.The sintered bodies can be manufactured by pressureless sintering at temperatures of from 2150.degree. to 2200.degree. C. from powder mixtures comprising lanthanum hexaboride and, in addition, mixtures of a carbon-containing material and a boron component.

Abstract: An electrically-conductive sintered compact of silicon nitride which is machinable by electrical discharge machining and a process to produce the same. TiN and/or TiC powder is added to a powder of silicon nitride in an amount 15-40% by volume to act as a conductivity-supplying agent while 0.01-3.0% by volume MgO and/or Al.sub.2 O.sub.3 powder is added as a sintering assistant. The mixed powders are then preformed in a desired shape and sintered in a nonoxidizing environment at 1,600.degree. C.-2,000.degree. C. to obtain a compact of silicon-nitride machinable by electrical discharge machining due to its electrical conductivity being at least 1 S.multidot.cm.sup.-1.

Abstract: The invention is directed to a thick film resistor composition for firing in a low oxygen-containing atmosphere comprising finely divided particles of (a) a semiconductive material consisting essentially of a refractory metal carbide, oxycarbide or mixtures thereof and (b) a nonreducing glass having a softening point below that of the semiconductive material dispersed in (c) organic medium and to resistor elements made therefrom.

Abstract: A process for preparing a metamorphosed metal oxide, which comprises heating, under a non-oxidative (and not hydrogenous) atmosphere, a mixture of at least one metal oxide, said metal being selected from the group consisting of elements of Groups III, IV, V and II b and transition elements in Periodic Table, and a carbide represented by the formula:C(M).sub.zwherein M is an element except carbon selected from the group consisting of elements of Groups III, IV and V in Periodic Table, and Z is an integer corresponding to the valency of M, is disclosed. The process is simple and safe and the metamorphosed metal oxide obtained is modified in color tint and provided with electroconductivity.

Abstract: A sintered ceramic heater, particularly a heater for a glow plug of a diesel engine, includes a sintered ceramic heater, which generates heat upon receiving an electric current, supported by an electrically insulating sintered ceramic body. The heater element includes a U-shaped cross-section outer portion integrally sintered with and covering a central portion. Each portion is formed of a sintered ceramic body of a mixture of electrically conductive ceramic powder having an average diameter of not more than 2 .mu.m and selected from the group consisting of MoSi.sub.2, WSi.sub.2, TiB.sub.2 and TiC, and 35-75 mol % of electrically insulating ceramic powder, e.g., Si.sub.3 N.sub.4. The central and outer portions have the same composition.

Abstract: An electrical contact formed of a mixture of finely divided electrically conductive metal doped with graphite or cadmium oxide. A thin coating of the electrically conductive metal is disposed upon the side of the contact which is adapted to be welded or brazed to an electrically conductive support. The electrical contact is made by mixing the finely divided cadmium oxide and pressing the mixture into a desired shape. A slurry of conductive metal is then sprayed on one side of the contact. After coating, the contact is sintered at a temperature less than the melting point of the electrically conductive material, whereby the contact is formed and the coating is firmly attached to it. The invention is particularly useful with silver or copper-based electrical contacts.

Abstract: A ceramic heater of the present invention comprises a sintered heating element bonded to a supporting substrate or a sintered element alone. A sintered body comprises the heating element is mainly composed of silicon nitride with such sintering agents as yttrium oxide to be superior in strength, thermal shock resistance and thermal resistance. The sintered body also includes 10-80 mol % of titanium carbide, titanium nitride or a mixture thereof which are electrically conductive ceramics so that the specific electrical resistance can be controlled.A method for producing a ceramic heater of the present invention consists of the first process in which a powdery mixture is prepared by mixing powders which are made to have structures of a solid solution by previous calcination of silicon nitride and a sintering agent and powders of conductive ceramics which comprise either or both of titanium carbide and titanium nitride, and the second process in which such powdery mixture is formed and sintered by heating.

Abstract: A process for preparing metamorphosed alkaline metal titanates which comprises heating a mixture of at least one alkaline metal compound capable of being decomposed into an oxide of the alkaline metal and a gas by heating, and titanium dioxide, under a non-oxidative atmosphere, in the presence of at least one carbide represented by the formulaC(M).sub.z (1)wherein M is an element except carbon selected from groups III, IV and V in Periodic Table, and z is an integer corresponding to valency of M.The products have excellent heat resistance and electroconductivity and are useful as insulating materials.

Abstract: An electrically conductive ferrofluid composition and a method of preparing and using the ferrofluid composition in a ferrofluid seal apparatus, and which ferrofluid composition comprises a liquid carrier having a colloidal dispersion of ferromagnetic particles in an amount sufficient to provide magnetic properties to the ferrofluid composition and carbon particles in an amount sufficient to provide electrical conductive properties to the ferrofluid composition, the ferromagnetic and carbon particles stabilized in the ferrofluid composition by a surface active dispersing agent. The electrically conductive ferrofluid composition is usefully employed in a ferrofluid exclusion seal apparatus to provide an electrically conductive seal apparatus particularly useful for computer disk drives and sputtering apparatus in the semiconductive industry.

Abstract: Fine spherical amorphous powder represented by the general formula:SiCxNyHzwherein 0.1<x<2.0, 0.1<y<1.5 and 0<z<4, is prepared by vapor phase oxidation of organosilicon compound substantially free from halogen atoms and oxygen atoms. An ultimately crystalline, uniform and fine powder of silicon nitride and silicon carbide is prepared by heat treatment of the fine spherical amorphous powder. The powder and the crystalline uniform, and fine powder are used as raw materials for composite ceramics and as functional materials for solar cell.

Abstract: An electrically conductive sintered ceramics of the present invention comprises, as the main ingredients thereof, (a) silicon carbide, (b) an inorganic compound which exhibits a positive resistance-temperature coefficient, and preferably (c) a sintering assistant. The electrically conductive sintered ceramics obtained exhibits a positive resistance-temperature coefficient as a whole.A ceramic heater of the invention makes use of the electrically conductive sintered ceramics in an electrically conductive portion thereof.A sintered product which exhibits a positive resistance-temperature coefficient helps to prevent the occurrence of thermal runaway or thermal destruction.

Abstract: A ceramic heater having a heating element of a sintered mixture comprising alumina, titanium nitride and titanium carbide, is discribed. The heating element has a good oxidation resistance, and a relatively high temperature coefficient of resistance. The larger composition of titanium nitride acts to increase the temperature coefficient of resistance. The larger composition of alumina acts to prevent oxidation increase and to improve the sintering. The adequate composition of each ingredients can result in a suitable heating element for a ceramic heater.

Abstract: A particulate mixture of ceramic powder, free carbon and a hydride of a metal selected from the group consisting of hafnium, niobium, tantalum, titanium, vanadium, zirconium and mixtures thereof is hot pressed decomposing the hydride and reacting the resulting metal with carbon producing a polycrystalline microcomposite comprised of a continuous phase of the carbide of the metal which encapsulates at least about 20% by volume of the ceramic particles and which either encapsulates or is intermixed with the balance of said ceramic particles.

Abstract: Electroconductive ceramic materials with high density, high mechanical strength, high endurance to repeated current supply and excellent thermal shock resistance can be obtained by mixing 5 to 70 parts by weight of Al.sub.2 O.sub.3 or alumina ceramic materials containing 95% by weight or more of Al.sub.2 O.sub.3 and 30 to 95 parts by weight of at least one electroconductive material selected from of ZrB.sub.2, ZrC, ZrN, ZrSi.sub.2, TaB.sub.2, TaC, TaN, TaSi.sub.2, TiB.sub.2, TiC, TiN, Mo.sub.2 B.sub.5 and MoSi.sub.2 adding a molding binder, molding the mixture and sintering the molded mixture. The electroconductive ceramic is usable for heaters, glow plug heaters, electrical gas ignitors, kerosine gasifying burners, and electrodes or conductors for water processing or dialysis.

Abstract: The invention is refractory, electrically conductive, mixed materials based on hexagonal boron nitride and at least one electrically conductive component such as titanium boride and zirconium boride, and having a density of at least about 95% of the theoretical density and nondirection-dependent properties, which have been manufactured from powder mixtures that are practically free of oxygen and metal and comprisefrom about 10 to 60% by weight of boron nitride,from about 0 to 60% by weight of aluminum nitride and/or silicon nitride, andfrom about 30 to 70% by weight of an electrically conductive component,without the concomitant use of sintering aids by means of isostatic hot pressing in a vacuum-tight casing at temperatures of from about 1400.degree. to 1700.degree. C. and under a pressure of from about 100 to 300 MPa. The powder mixtures are pre-densified to form green bodies in block form and are then introduced into casings or coated with a material forming a vacuum-tight casing.

Abstract: A new silver dispersion coating composition containing a special additional pigment material useful as an electrically conductive coating on electronic equipment or the like. The new coating composition maintains high electrical conductivity at a significant economic advantage over similar prior coating compositions.

Abstract: A new nickel dispersion coating composition containing a special additional pigment material useful as a shielding coating to protect electronic equipment or the like from electromagnetic interference (EMI). The new coating composition is more economical to produce than prior coating compositions without significantly effecting performance characteristics.

Abstract: Ceramics incorporating fibrous crystals of silicon carbide, optionally, in combination with an electroconductive substance have high electroconductivity and are amenable to electric discharge machining.

Abstract: A composite silicon carbide sintered shape is provided in two forms in which the former form includes rare earth oxides as a sintering assist, and the latter form includes rare earth oxides and/or aluminum oxide or boron oxide as a sintering assist, characterized in that both forms have a surface layer abundant in rare earth oxides. Methods for manufacturing such sintered shapes are also provided.

Abstract: An amorphous silicon semiconductor of the general formula: a-Si.sub.(1-x-y) C.sub.x N.sub.y containing hydrogen and/or fluorine, which provides an amorphous silicon PIN junction photovoltaic device having an improved conversion efficiency when it is used as a P-type or N-type layer on the light impinging side of the PIN junction photovoltaic device. Also, the conversion efficiency of an amorphous silicon PIN junction photovoltaic device is improved by using a two-layer film structure of ITO and SnO.sub.2 as a transparent electrode for the photovoltaic device, with the SnO.sub.2 layer contacting the P or N layer. The improvement is particularly marked in the case of heterojunction photovoltaic devices.

Abstract: A high-temperature thermistor comprising, a polycrystalline sintered body consisting essentially of 0.1-8 weight percents of at least one kind selected from the group consisting of Be, BeO, Be.sub.2 C, B, BN, B.sub.2 O.sub.3 and B.sub.4 C which weight percents are calculated as the amount of only Be or B single substance from net amount, the balance SiC, and the inevitable impurities having not more than 2 weight percents of SiO.sub.2, not more than 0.1 weight percent of Al, not more than 0.2 weight percents of Fe, not more than 1 weight percent of Si, and not more than 0.4 weights percents of free carbon, a pair of electrode provided on the surfaces of the sintered body, and lead wires each connected to the respective electrodes, and a method of producing same.

Abstract: Silicon carbide material retains the hardness, wear and heat resistance properties and can be rendered conductive by the incorporation of an element of the same valence as silicon and carbon in quantities in the range of 0.01% to 0.03%. Germanium in this range in SiC is conductive. The material is very hard, is electrically conductive in the 2.times.10.sup.-4 ohm cm range and is useful in highly corrosive and abrasive applications.

Abstract: A ceramic heater having a heating element of a sintered mixture comprising alumina and titanium nitride and/or titanium carbide. The heating element has a specific resistance in a range from 10.sup.-4 to several .OMEGA.cm. The ceramic heater may have supporting substrates of insulating materials with which the heating element is covered. The ceramic heater can be used at a temperature above 1000.degree. C.

Abstract: Electrically conductive articles which comprise a non-conductive substrate having thereon a substantially uniform, electrically conductive dispersion of finely divided particles of ferroalloys, silicon alloys, or mixtures thereof, are described. The articles are useful as components of electrical switches, contacts, connectors, circuit boards or electromagnetic interference shields. The conductive portion of the article may be subsequently electroplated or electrostatically painted.

Abstract: Silicon carbide shapes of the general type shown and described in U.S. Pat. No. 4,125,756 are densified and nitrided in such a way as to produce shapes with improved durability and reduction in temperature span in response to voltage changes.

Abstract: Electrically conductive articles which comprise a non-conductive matrix containing an electrically conductive dispersion of finely divided ferroalloy, silicon alloy, or mixtures thereof, are described. Compositions for making the articles utilizing various non-conductive materials e.g., plastics, ceramics, and glass, are also described.

Abstract: Semiconductive barium titanate having a positive temperature coefficient of resistance comprises a barium titanate semiconductor including barium titanate and a small quantity of a doping element, and at least one additive selected from among silicon nitride, titanium nitride, zirconium nitride and silicon carbide. The semiconductive barium titanate of this invention has a sharp rise in the variation of specific resistivity with temperature change and a large specific resistivity ratio in the PTC temperature region, and can be produced with high reproducibility, since a widely differing quantity of the doping element can be effectively added to barium titanate.

Abstract: Nickel powders having an improved chemical stability are formed by reaction with an electroconductive coating such as a carbide, a silicide, or the like and, also, a reaction with sulfur.

Abstract: A composite element comprises a matrix composed of at least one member selected from the group consisting of oxides, carbides, nitrides and borides and a fibrous material made of at least one member selected from the group consisting of carbon, graphite, oxides, carbides, nitrides and borides. A plurality of composite elements are used as the electrode wall or insulating wall constituting an MHD power generating channel.

Abstract: The overload protection material of this invention comprises a plastic preferably an elastomer, e.g. silicone rubber, homogeneously and highly loaded with silicon carbide particles (powder) and a lesser amount of a Group IV B element-carbide particles (powder). The material is preferably form stable and is placed (across) a semiconductor junction or between electrodes of a device to be protected so that when high voltage surges appear across the junction or device to be protected the material breaks down (conducts) before the junction or device is destroyed. The material is bidirectionally conductive in its voltage threshold characteristic and repeatedly recovers unlike a fuse so that it provides continuous high voltage over-voltage (e.g. surge) protection.

Abstract: An oxide-coated cathode for electron tubes comprising a base metal plate made of an alloy containing nickel as a major component and at least one high-melting point metal in an amount of 2% by weight or more, and if required, a small amount of one or more reducing elements, and an electron emissive alkaline earth metal oxide layer adhered to the base metal plate, characterized by having a carbide layer made of at least one carbide of Si, B, Ti, Zr, Hf, V, Nb, Ta, Mo or W between the base metal plate and the electron emissive alkaline earth metal oxide layer can maintain electron emitting life for a long period of time due to the prevention of interfacial reaction between the base metal layer and the alkaline earth metal oxide layer.