The very high temperature required to cast Pt/10% Ir can result in very slight surface erosion due to metal-mold reaction. Iridium has the highest melting point of all of the platinum group metals (2,454☌ vs. Traditionally, the most popular casting alloy in the U.S, this alloy does not form an oxide film when molten (unlike Pt/Ru), thereby allowing for fine detail pieces to be quite easily reproduced. Platinum containing 10% Iridium is a medium hard alloy (110 HV – annealed state) with fairly low ductility, and is thus workable for most manufacturing processes. Fine section items are also difficult to fill due to ruthenium’s affinity for oxygen, resulting in porosity. However, by comparison to other available alloys, it is not the most appropriate alloy for casting due to metal-mold reaction, producing surface roughness. It is therefore an excellent alloy for use in manufacturing rings from Pt/Ru tubing. These three properties of Pt/Ru combine to give it particularly good machining and polishing characteristics. The alloy also has a high tensile strength. In its wrought state, it has an annealed hardness of 120 HV (Vickers hardness), and a steady working hardness of approximately 220 HV. Ruthenium is a grain refiner, meaning it gives the alloy a tight grain structure. The following is a brief description of the general properties and applications of the most popular Pt alloys currently in use in the U.S. Using a small brush for application, protect all stones by coating them with a boric acid fire coat. When this is the case, it is better to use white gold solder and have a visible seam rather than damage a stone. Caution is advised when sizing heavy bands and when channel-set stones are involved. To avoid damage to prong-set stones, orient the stones at six o'clock and the seam to be soldered at twelve o'clock then direct the flame upward to the seam. A sharp, slightly oxidizing flame works best for Platinum.Īll Platinum solders flow at temperatures greater than any stone - including diamond - is capable of withstanding. Acetylene, which is rich in carbon, is never recommended. Use a hydrogen torch or oxy/natural gas or oxy/propane gas torch. Flux and boric acid fire coat are unnecessary and may cause Platinum to become brittle when performing high temperature solder operations. Apply heat directly to the solder and seam until the solder flows. Place the solder chip in the seam not on top of the seam. All platinum solders below 1,700☌ will result in a dark, visible seam line. However, soldering may be used to join these two alloys and 1,700☌ solder is the best choice whenever this is necessary. Joining Platinum/Cobalt and Platinum/Iridium by fusing is not possible due to differences in melting temperatures of the alloys. Platinum/Iridium, Platinum/Ruthenium, or Platinum/Cobalt stock may be used when sizing up, however it is best to use stock of the same alloy as the ring. Carbon is probably the most frequent cause of contamination when soldering platinum. Use only ceramic or refractory supports never use charcoal or other carbon fixtures. Steel and titanium soldering tools will result in contamination. Use only a tungsten carbide solder pick and tungsten carbide or ceramic tipped tweezers. Clean, pickle, and rinse all components thoroughly. Attempting to fill large gaps will result in pitting and visible seams. This also holds true with finishing buffs and compounds. Contamination may occur from tools used to work silver and gold. Sunglasses do not provide adequate protection.īegin with a saw, files, and other tools reserved only for working platinum. Permanent damage to your eyesight may occur as a result of UV exposure. Solder platinum only if #5 or #6 welding safety glasses protect your eyes.
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