Purple gold:
Purple gold (also called amethyst gold and violet gold) is
an alloy of gold and aluminium rich in gold–aluminium intermetallic (AuAl2). Gold content in AuAl2 is around 79% and can therefore be referred to as 18 karat gold.
When pure gold is mixed with aluminum in a
ratio of 79% gold and 21% aluminum in a vacuum furnace the resultant product is an 18ct gold that is purple in colour. ( okay, for the purists, the ratio is higher that 18ct, since 18ct is 75%/ gold and 25% alloy, but to all intents and purposes you can sell it as 18ct gold.)
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https://patents.google.com/patent/CN102676864A/en
>The formula comprises the following substances in percentage by weight: 21.2-21.6 percent of aluminum, 0.3-0.7 percent of copper, 0.03-0.5 percent of rare earth and the balance of gold
>The method comprises the following steps of: (1) selecting a group of proportions according to the formula range, and calculating the weight of each substance according to the weight of the alloy which is required to be prepared; (2) adding a gold block into a crucible and heating to 1,100-1,200 DEG C to fully melt the gold block; (3) firstly adding the aluminum into the crucible, then adding the copper and finally adding the rare earth according to the formula, stirring uniformly and preserving heat at 1,100-1,130 DEG C for 0.5-1 hour; and (4) molding and annealing a molded rough blank at 900-1,100 DEG C for 25-50 hours to prepare the purple K gold. According to the formula and the preparation method, the machining performance of the purple gold is effectively improved while a lilac color of the K gold is guaranteed, and the ductility of the K gold is improved, so that the purple K gold can be machined and applied in more ornaments.
>the prescription of a purple karat gold, it is characterized in that comprising the material of following each weight percent: aluminium 21.2%~21.6%, copper 0.3%~0.7%, rare earth 0.03%~0.5%, surplus are gold
each weight percent: aluminium 21.4%, copper 0.6%, rare earth 0.2%, surplus are gold.
>comprise a kind of rare earth metal in lanthanum, cerium, praseodymium, neodymium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, lutetium, scandium, the yttrium in the said rare earth at least.
>Steps to make it:
(1), according to the selected assembly ratio of above-mentioned formula range, again according to the weight alloy of required preparation, calculate the weight of each material;
(2), in crucible, add gold bullion and be heated to 1100 ℃~1200 ℃ it is melted fully;
(3), earlier in crucible, add aluminium by prescription again, add copper again, add rare earth at last, stir, 1100 ℃~1130 ℃ insulations 0.5~1 hour;
(4), the reverse mould moulding, the anneal that the thick embryo of moulding carried out under 900 ℃~1100 ℃ 25 hours~50 hours makes.
6. method according to claim 5 is characterized in that: the anneal time is 36 hours in the said step (4).
7. method according to claim 5 is characterized in that: the fusion in said step (2) and (3) is under the protection of inert atmosphere, to carry out.
8. according to claim 5 or 6 or 7 described methods, it is characterized in that: the anneal in the said step (4) is under the protection of inert atmosphere, to carry out.
>One of characteristics of gold are exactly soft, so when embedding gem, come off easily owing to insufficient strength.Therefore, people add metals such as silver, copper, zinc to increase the intensity and the toughness of gold in gold, and the gold jewellery of processing is like this claimed karat gold again., bullion nearly all comes embedding gem in inlaying with the karat gold of different K number.So both reached the noble quality of gold, remedied its deficiency again, and can be mixed with shades of colour as required, karat gold be in the bullion the most frequently used with change the abundantest material.
>The relational expression of K number and Gold Content: Au wt%=K/24 * 100%.Karat gold can be mixed with shades of colour as required, and popular karat gold jewellery shades of colour has in the world, and common generally have yellow and white.
Its complicated.