iiililiili^ @ EuroPean Patent Office ^-S Office europeen des brevets (fi) Publication number: 0 422 047 B1 @ EUROPEAN PATENT SPECIFICATION @ Date of publication of patent specification : @ Int. CI.6 : F21H 1/02 10.05.95 Bulletin 95/19 (2j) Application number : 89906887.8 (22) Date of filing : 24.05.89 (86) International application number : PCT/US89/02253 (87) International publication number : WO 89/12200 14.12.89 Gazette 89/29 (54) GAS MANTLE TECHNOLOGY. (30) Priority : 06.06.88 US 203312 (73) Proprietor : White Consolidated Industries, Inc. 11770 Berea Road (43) Date of publication of application Cleveland Ohio 44111 (US) 17.04.91 Bulletin 91/16 @ Inventor : DIEDERICH, Walter, J. (45) Publication of the grant of the patent : 52 Church Street 10.05.95 Bulletin 95/19 West Newbury, MA 01985 (US) @ Designated Contracting States : (74) Representative : Kirschner, Klaus Dieter, AT BE CH DE FR GB IT LI LU NL SE Dipl.-Phys. et al Patentanwalte Herrmann-Trentepohl, Kirschner, (56) References cited : Grosse, Bockhorni & Partner DE-C- 41 945 Forstenrieder Allee 59 FR-A- 2 551 178 D-81476 Miinchen (DE) GB-A- 1 682 CO h- o CM CM Note : Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been LU filed until the opposition fee has been paid (Art. 99(1) European patent convention). Jouve, 18, rue Saint-Denis, 75001 PARIS 1 EP 0 422 047 B1 2 Description ameter and that include a significant number of grains of dimensions in the order of one to two micrometers. This invention relates to gas mantle technology The mantle structures are efficient in converting ther- and more particularly to mantle structures for use mal energy to radiation energy in the visible spectrum with fuel burning devices such as portable fuel- 5 (radiation in the 400-700 nanometer range). burning devices to provide visible radiation. In preferred mantles, the erbia-ceria structure is Incandescent gas mantles were products of ma- fabric-like, for example, in woven, braided, or knitted jor commercial importance in the latter part of the form, and formed so as to provide a self-supporting nineteenth century and into the early part of the twen- dome of erbia-ceria filaments which is heated to in- tieth century. Early mantles, made of oxides of cal- 10 candescence by a gas flame. This dome of erbia-cer- cium, magnesium, zirconium, lanthanum, yttrium and ia filaments can be distorted to a large degree by an the like, provided inadequate lighting power. DE-C-41 external force; in such distortion the filaments bend 945 describes a variety of mantle compositions in- or twist elastically, and when the force is removed cluding mixtures of the above materials with consid- they regain their original shape, restoring the initial erable amounts of ceria; in Example 8 a mantle for 15 configuration of the mantle. Mantles in accordance providing "green-like" light formed from a mixture of with this aspect of the invention are able to undergo 50% thoria and 50% erbia; and in Example 12 a mix- large elastic distortions without fracture. ture of 30% Ceroxyd, 20% Lanthanoxyd, 10% Yttriu- Mantle shock resistance depends upon such fac- moxyd and 40% Zirconoxyd. Thorium oxide-cerium tors as mantle size and shape, characteristics of the oxide mantles (with minor additives) subsequently 20 precursor substrate used in manufacture (such as became the standard for gas light illumination. Those yarn size, type of weave, open area), processing con- mantles, however, have poor strength and durability, ditions and mantle support. Ausef ul shock resistance and also involve problems in both manufacturing and figure of merit for a cantilever supported mantle use. Thorium compounds are radioactive and require whose length and diameter dimensions are similar is special handling precautions which makes those 25 provided, to a first order approximation, by the prod- manufacturing procedures complex, difficult and uct of the shock load (in g's) that the mantle with- costly. Also, those mantles are relatively fragile after stands and the unsupported length (in meters) of the they have been fired. Thoria mantles of greater mantle. The shock load is the force experienced by strength and durability have recently been described, the unsupported mantle as a consequence of rapid as has an yttrium oxide-cerium oxide mantle which is 30 deceleration on impact of the support tube against a alleged to retain its mechanical strength better than stop; this load is commonly expressed in g's, where g commercial thoria mantles. FR-A-2 551 178 de- is the acceleration due to gravity. Impact loads can in- scribes a process in which a woven cloth of combust- volve deceleration forces substantially in excess of ible filaments, such as rayon or cotton, is impregnat- the force of gravity. Mantle structures in accordance ed with an aqueous solution of metal nitrates; and the 35 with this aspect of the invention preferably have a applied nitrates are then converted to the corre- shock resistance figure of merit of at least three g-me- sponding hydroxides with ammonia gas or aqueous ters. ammonium hydroxide. The choice of processing conditions depends on GB 1682 discloses a method for production of the shape and chemical composition of the organic hoods or mantles for gas burners which uses solu- 40 fabric and on the cerium and erbium compounds em- tions including erbium and other elements but no ce- ployed in the embodiment. A preferred organic mate- rium. The mantle is impregnated with the solution and rial for use in producing mantles of the invention is afterwards subjected to heat, so that the fabric is con- low-twist rayon yarn. However, other materials that sumed. absorb adequate amounts of the imbibing solution The invention provides a self-supporting gas 45 and that thermally decompose without melting, such mantle structure with the features of claim 1 methods as cotton, wool, silk and certain synthetic materials of manufacturing the same and preferred embodi- may also be used. ments are characterized in the subclaims. Preferred erbium and cerium compounds are ni- In accordance with one aspect of the invention trates. The erbium and cerium compounds can be im- there is provided an improved gas mantle structure 50 bibed into the organic material (uniformly distributed comprising a self-supporting erbia-ceria structure within the fibrils) by any of several methods. In par- that has golden white color (a color temperature of ticular processes, the fabric is imbibed in an aqueous about 2300K) when energized. The erbia-ceria struc- solution of nitrate salts that have a molar concentra- ture contains from about one percent to ten percent tion of less than 1 .4, preferably in the range of 0.8-1 .1 by weight of cerium oxide and preferably has a shock 55 molar, particular compositions containing erbium ni- resistance figure of merit of at least three g meters. trate and cerium nitrate in concentrations such that The inventive mantle structure is composed of erbia- the final sintered product contains ceria in the amount ceria filaments that are five - ten micrometers in di- of 3.0 - 4.0 weight percent. Minor amounts of other 2 3 EP 0 422 047 B1 4 materials may also be included. made by dissolving nonradioactive nitrates of erbium The elementary erbia-ceria fibers of inventive and cerium in distilled water and mixing the salt sol- mantles have a cross section dimension of less than utions. An organic multif iber fabric in the form of a ten micrometers and the preferred mantle fabric has tubular sleeve is immersed in the imbibing mixture open area of greater than fifty percent. In a dome 5 and gently agitated to promote penetration of the im- configuration that defines a volume of about 0.1 cubic bibing solution into the organic fibers. After imbibi- centimeter and with a skirt portion shrink secured to tion, the sleeve is removed from the solution and a heat resistant support tube, the mantle withstands compressed and then centrifuged to remove surface shock loads in excess of 600 g's. liquid, tied off and formed into a mantle sock, and In preferred embodiments, the mantle filaments 10 dried. The shiny white imbibed mantle sock fabric is contain erbium oxide in an amount in the range from then thermally processed under controlled condi- 90 percent to 99 percent by weight (more preferably tions. Initially, the temperature of the fabric is gradu- in the range from 96 percent to 97 percent by weight); ally increased in an atmosphere that contains a re- and the mantle filaments contain cerium oxide in an duced amount of oxygen (preferably an oxygen par- amount in the range from one percent to ten percent rs tial pressure of less than 1 00 mmHg). Aquite vigorous by weight (more preferably in the range from three reaction, which occurs when the mantle fabric has percent to four percent by weight). The metal oxide fi- reached a temperature of 130-1 70°C, involves an in- laments of such a mantle, after heating in an isobu- teraction (termed herein "nitrate burn") between the tane flame, have a microstructure including a signif- nitrates and the cellulosic fabric, which reaction is vis- icant number of grains of dimensions in the order of 20 ually evidenced by a color change that starts at some one to two micrometers, and are efficient in convert- location in the fabric and produces a front which sep- ing thermal energy to luminous energy in the visible arates a tan color from the shiny white color and ad- spectrum.