Patented June 20, 1944. 2,351,974

UNITED STATES PATENT OFFICE PRODUCTION OF SILVER PREPARATIONS Max Kolmar, Frankfort-on-the-Main, Germany; wested in the Alien Property Custodian No Drawing. Application September 24, 1940, Se rial No. 358,184. In Germany September 29, 1939 . 6 claims. (CI. 106-1) My invention relates to the production of silver - If desired, the new silver preparations may preparations for surface silvering of refractory contain also some other fluxes, for instance, lead or ceramic material, for example, glass, quartz, or bismuth compounds. These relatively low mica, stone ware, portelain, magnesium silicate melting - additions have but an adhesive effect containing fragments or the like. More specifi 5 and do not improve the other qualities, such as cally it relates to the production of silver prepa refractoriness, of the silver coatings. rations containing oxides of the raire earths or - The amount of my new additions may vary Other base metals, particularly manganese or its in wide ranges. In general, it is advantageous to compounds. keep the addition below 10%, preferably even be Surface silvering may also be applied to highly low 1% of the Whole mixture. - refractory substances such as, for instance, sin * - / Eacamples tered aluminium oxide, or masses containing mainly titanium dioxide, beryllium oxide or zir (1) 20 grs. finely divided silver powder are coniumw oxide. Thus the silvering may be em- . mixed with 1. g. basic bismuth nitrate, 4 grs. re ployed either as decoration or as an electrically, Sinic acid manganese and 75 grs. of a 50% resin conducting surface to be used for electrotechni solution in oil of turpentine. This preparation cal purposes, especially in high-frequency prac i applied to glazed porcelain, dried and fired at 30° C. tice.If the usual silver preparations combined with A firmly adhesive, coating of good conduc fluxes, solvents and Suspension means are ap 20 tivity of a beautiful metallic appearance is ob plied to the aforementioned substances or objects tained. If desired, this coating may be polished and subsequently fired, the resulting coatings are as usual, in order to increase its metallic bright very defective, especially when only small quan ness. The same excellent results will be ob tities of silver have been used on account of eco tained by substituting the above mentioned nomic reasons. These coatings also show, poor 25 quantity of manganese to one-third for uranium adherence, reduced electric conductivity and are Oxide. lacking in appearance. It Was therefore indis (2) The silver preparation was mixed accord pensable to add a small quantity of a noble ing to Example 1 with the difference only that metal, for example iridium, to the silver prepa instead of manganese oxide half the amount of 30 nickel was used. A sheet of mica, was covered rations which addition was sufficient to produce with this preparation and fired at a tempera Well adhesive suitable silver coatings of consid ture of about 600 C. The coatings thus obtained erable refractoriness. show a very good electric conductivity and may In an effort to avoid the addition of the ex be utilized for the manufacture of, for instance, pensive noble metals I have made the observa 35 tion that excellent effects may be obtained in electric(3) Silver condensators. preparation, made according to Ex using silver preparations which contain also ample i, but adding the same amount of lantha metal Compounds or metals less noble than sil num oxide instead of manganese oxide. This ver,ing thepoint oxides than of thewhich usually have a?employed far higher fluxes. melt preparation was burnt into glass at a tempera Heavy metals have proved especially suitable, 40 ture of about 500. C. The thus obtained, sub thus, for example, cerium, lanthanium, thorium, stances may be employed for decorative pur uranium tantalum, nickel or the like. According pOSes as Well as electric purposes of all kinds. to my invention, manganese exerts the most What I claim is: suitable effects. The aforementioned metals may 1. A preparation for silvering the surfaces of be employed either per se or in form of their 45 ceramic ware by firing which comprises a flux, compounds as, for instance, oxides, or salts, but a solvent vehicle, silver, and a compound of a especially in form of their organic compounds. heavy metal whose oxide has a melting point . It has proved advantageous to use such Organic higher than that of said flux, said heavy metal compounds which are sufficiently soluble in the being Selected from the group which consists of . utilized solvents, for example, resinates, acetyl 50 manganese, cerium, lanthanum, thoriuin, ura acetonates, oleates or the like. All these sub nium, tantalum, and nickel. s. stances may be employed either alone or in any 2. A composition as defined in claim 1 wherein desired mixture. Of course, an addition of Small the heavy metal compound added comprises less quantities of iridium may also be provided for, than 10% by weight of said preparation. but in general such an addition is not necessary. 55 3. A composition as defined in claim 1 where

2 2,851,974 in the heavy metal compound added comprises less than 1% by Weight of said preparation. ceramic ware by firing which comprises a flux, 4. A preparation for silvering the surfaces of compound.a solvent vehicle, metallic silver, and a nickel ceramic ware by firing which comprises a flux, 6. A preparation for silvering the surfaces of a solvent vehicle, metallic silver, and an Organic compound of manganese soluble in said solvent ceramic ware by firing which comprises a flux, system. 8.Oxide. vent vehicle, metallic silver, and lanthanum 5. A preparation for silvering the surfaces of Max KOLLMAR.