The gold solder, gold alloy interface

With soldering the physical properties of the basis metal must be maintained and a minimum of molten metal is used. An examination of joints in 17 gauge platinized gold wire is made with 18 k gold solder following quenching immediately after flow and cooling in air; there is a widening of grain boundaries and intergranulation penetration in the latter method. A comparison with the cast gold joint is made. Some inclusions were noted.

[The dental soldering by means of high frequency induction heating (author's transl)]

The authors examined the methods of high frequency induction soldering, especially Loop-method, other than the gas flame soldering which was known generally. The details which was done are: (1) about the form of induction coil, and the relative places of the coil and restrative appliance, and some supplementary appliances of them. (2) about strength of soldered joints of Co-Cr wire using silver solder and Pd-solder, and observation on the corrosion of soldered-joints by the scanning electron-microscope. (3) about the comparison of the characteristics of Co-Cr wire by means of high-frequency induction heating and gas-flame one. (4) about the examples of soldering of porcelain crown-bridge and clasp wire attached on the dental cast, and possibility of soldering techniques of them on the dental cast. The authors found that the high frequency induction method was preeminent from the other method on the point of (a) the characteristic of heated wire, (b) the strength of soldered joints, (c) the easiness of operating of them, and (d) the possibility of soldering using the high-melting point of Pd-solder, and the soldering of them on the dental cast. Therefore we can enough respect the application on the dental area of this apparatus and this techniques of the high-frequency induction soldering.

Heat treatment of laser-welded gold alloys

(1) Three alloys, G-3, SMG-2, and Ceramco-0, showed no ductility in the aswelded condition. (2) The Ney G-3 as-welded samples had no ductility, but heat treating greatly increased their yield stress. (3) The simulated ceramic firing cycle created a small amount of ductility in SMG-2, but the lowering of the yield stress in Ceramco-0 renders the welds dangerously weak even with improved ductility. (4) The Jelenko F as-welded specimens were acceptable. Heat treatment improved the joints slightly, but this is not considered necessary. (5) The Ney B-2 as-welded specimens produced satisfactory joints which did not benefit from heat treatment. The large loss in ductility with heat treatment is considered undesirable. (6) The unpredictable behavior of Ceramco-0 in this study suggests the need to evaluate each alloy individually before clinical application.

Preceramic and postceramic solder joints

This investigation evaluated preceramic and postceramic soldering procedures. Three gap spaces and two soldering methods were evaluated. Wider gaps produced stronger joints. The strongest joints were achieved by using wider gaps and the oven soldering technique. Very wide gaps (0.76 mm.) are not recommended because of possible distortion through excessive solder shrinkage. However, in practice, many solder joints exceed the 0.31 mm. recommended minimum; these joints will not show decreased strength.