Hard solder

Hurtling, m. (Metal.) hard slag, also salamander. Harriot, n. hard solder, hartloten, v,t. hard-solder, t aze. 

Martensitic stainless steels are usually used in the softened (tempered at or above 650°C) or in the fully hardened condition (tempered at or below 250°C) so that there is no substantial reduction in corrosion resistance resulting from carbide precipitation. However, the hard soldering of knife blades can result in carbide precipitation and pitting of the blade at the area adjacent to the handle, and care must be taken in the soldering process to avoid this danger. 

Potassium fluoride is a fluorinating agent in organic synthesis. Other applications are in making insecticide formulations, as an additive to flux for making hard solder, and to control fermentation. 

The best material for a fusion apparatus (see Fig. 14a) in the laboratory is copper, which saves on gas because of its good conductivity and which is therefore economical in operation. (It is important that the melt does not come in contact with two diflFerent metals, because then a galvanic cell is formed which causes deleterious oxidation and reduction reactions.) The high fusion temperature makes it essential that the stirrer sweep over the whole surface of the fusion vessel (see sketch). The thermometer is inserted in a copper tube closed at the end with hard solder and filled with dry cylinder oil to such a depth that at least 10 cm. of the thermometer is immersed. It may be practical also to insert the thermometer in the hollow shaft of the stirrer (Fig. 14b). 

Silver solder is a common form of hard solder it is an alloy of silver and copper, usually with zinc and sometimes tin or cadmium added. Silver solders melt in the range 600 to 700°C and have high mechanical strength. 

There are two types of solders soft and hard. Soft solders usually consist of a mixture of lead and tin and the heat required to melt them is supplied by a soldering iron. Hard solders include brass (copper-zinc alloys) solders, silver solders, copper solders, nickel-silver solders, and solders for light alloys the heat to melt them is usually supplied by a blow torch. 

Hard Soldering.— To Solder Brass. in Chapter XQ, which about covers the w hole l ing, varying only in the composition of the solder for different metals. Tho biiiss solder there described acts equally well for soldering copper, hut for silver a solder is made oompoeed of tw o parts silver and one part brass. 

Hard Solders.—I, A hard solder that is yellow and easily fusible is made of coi r, if parts, and zinc, 5L parts. 

To hard solder iron use good tough bra or sheet copper, with borax as a flux. 

Fine solder is an alloy of two parts of tin and one of lead. It melts at 360". Coarse solder, which melts at 500", contains one part of tin and three of lead. Hard solder, for copper, is a compound of copper and zinc, the latter metal being in excess. 

Hard soldering is applicable in most cases. Spelter solder, silver solder (m.p. about 700°C) and pure silver (m.p. 960°C) are used. The cleaned junctions are sprinkled with a generous amount of borax, and when they are sufficiently hot the solder (as powder or as wire) is added. With a large amount of borax and pure silver, even Mo and W can be hard soldered. 

A soft solder melts at a temperature in the range 200-300°C and consists of a Un-lead alloy. The tin content varies between 80% for the lower end of the melting range and 31% for the higher end. Hard solders contain substantial quanUUes of silver in the alloy. Brazing solders are usually alloys of copper and zinc, which melt at over 800°C. 

Aluminum fluoride Lithium fluoride flux, hard solder Potassium fluoride flux, magnesium prod. 

The hard solders are completely different to the above mentioned and are classified as ... 

---