Degussa Aktiengesellschaft

Umicore Ag & Co Kg

Hans-Martin Ringelstein

Walter Diehl

Bernd Kempf

Kurt Eiermann

Hans-Hermann Beyer

Karlheinz Eckert

Doris Hathaway

Georg Ptaschek

Gernot Schoeck

Roland Fuchs

Calogero DiVicenzo

Ekkehard Lange

Karlheinz Gleissner

Bernd Meier

The invention relates to a process and a device () for the production of spherical metal particles () from a melt (). In order to produce droplets a melt jet () is subjected to vibrations and is led through at least one nozzle (). In order to produce spherical metal particles () the droplets at the outlet of the nozzle () are fed to a coolant () for purposes of consolidation. The nozzle () dips into the coolant (), the temperature of the coolant () being below the melting point of the melt ().

Method and device for producing spherical metal particles

Gold-palladium alloys with a high gold content for dental applications should, for reasons of biocompatibility, not contain any toxically dubious components. For particularly corrosion-resistant and biocompatible Type 4 alloys, tin is needed as the only base-metal component in amounts between 0.7 and 5.8 wt % if one remains within defined limits in a palladium-tin diagram of FIG. 1, for Pt values less than 2%. Such alloys contain, in addition to gold and tin, 6 to 25 wt % palladium, 0 to 12 wt % platinum and 0 to 2 wt % of at least one of iridium, rhodium and/or ruthenium.

Gold-palladium alloys for dental materials

In order to manufacture flexible plastic bands of a thermoplastic synthetic resin containing 40% or more by volume hard materials and/or soldering powder, two grooved and heated shearing rollers arranged parallel to one another and running in opposite directions are used onto which components are applied. The front shearing roller must have a temperature of 25.degree. to 90.degree. C. on the application side and of 30.degree. to 80.degree. C. on the removal side, the rear shearing roller must have a temperature of 30.degree. to 130.degree. C. on the application side and on the removal side of 35.degree. to 100.degree. C., and the temperature of the rear shearing roller must be at least 5.degree. C. above the temperature of the front shearing roller. In addition, the front shearing roller must exhibit a speed of 5 to 25 rpms and the rear roller a speed which is 5 to 70% lower.

Method of producing flexible plastic bands compounded with hard-material

A meterial well-suited for gold fillings in tooth cavities consists of a porous sintered compact which is prepared from platelet-shaped gold powder produced by chemical precipitation and which exhibits a pore volume of 80 to 90%.

Tooth filling material and method of its preparation

A dental-filling material with hardnesses exceeding 100 HV for gold-condensation is prepared from a gold-alloy powder of which the alloying components are metals resulting in hardening gold alloys and which are simultaneously soluble in nitric acid. A rough, pure gold layer on the surface of the powder particles is obtained by treatment with nitric acid.

Dental filling-material and method for its preparation

Gold powder is inserted in a cavity for the production of fillings in teeth by means of filled gold and this is subsequently hardened mechanically. The moisture sensitivity of this process can be avoided by using a paste made of platelet shaped gold powder with a plastic, organic binder which liquifies at 20.degree. to 45.degree. C. and the mechanical hardening is carried out with ultrasonic.

Process and apparatus for the production of fillings in teeth

Powder of a ductile, mouth resistant metal such as silver, platinum, palladium, aluminum, or titanium, or an alloy thereof, or a cold weldable, mouth resistant synthetic resin, such as a polyacrylate or methacrylate, polycarbonate or polysulfone is worked to a paste with a plastic organic binder which liquifies at 20.degree. to 45.degree. C. This paste is hardened in the tooth cavity by ultrasonic action.

Growing community of inventors

Frankfurt-am-Main, Germany

Hans-Martin Ringelstein