Compared with other precious metals, platinum has three main characteristics:
1. Rare global platinum reserves are only over 600 cubic meters. Together, the global total can only fill two three-bedroom apartments. At present, the annual output of platinum is only 5% of that of gold. Only 150 tons of platinum can be mined in the world every year, of which 60 tons are used for jewelry. The total output of gold reaches 3300 tons every year. It has been estimated that if all the platinum mined before is put together, its volume is only equivalent to a cube 5 meters square, and the platinum reserves are not large. Usually the demand exceeds the supply. It takes 5-6 months to obtain a large amount of platinum, that is, 365,438+0.65,438+0 g, and 65,438+00 tons of ore can be processed before a "large amount of platinum ingots" can be cast from raw materials. It only takes 3-5 weeks to get the gold of the photo album, and 3 tons of ore can be extracted. In fact, there are only a few real estate countries in the world-mainly Zimbabwe.
Second, pure platinum jewelry generally has a purity of 95%, has a natural white luster, will not be corroded by acid and alkali, will not change color, and will not react with mercury. As long as it is maintained in the most common way, it will never lose its pure white luster. Other precious metals, such as low-purity silver and gold, will change color over time. No metal can be completely pure, and there are impurities mixed with other metals. Platinum has almost no impurities, and its purity is extremely high. It will not fade and change color, and it can still maintain its luster over time. The purity of platinum is also very suitable for skin, because unlike other metals, platinum does not cause allergic reactions.
Third, the eternal and tough platinum will scratch like all precious metals, but the scratch on the platinum surface is only the displacement of the metal surface. Its total weight will not be lost, so even if it is worn every day and leaves traces on the surface of platinum jewelry, it remains the same and is a symbol of eternal beauty.
1 g (about 3 1 g) of platinum can be drawn into filaments without breaking at a distance (about 42 kilometers) from the marathon track. If you press in platinum gold foil, it can be extended to the size of a tennis court. 1 g platinum can reach 1.6 km without breaking if it is drawn into filaments. Therefore, the toughness of platinum is very good, and it is especially suitable as an inlay material. The most famous diamonds in the past, from the famous "Indian Diamond" collected by the King of England to the "Star of Africa", are all set in platinum. Some insurance companies can also reduce the insurance premium for jewelry inlaid with platinum.
In addition to the above main features, platinum has other important features: firstly, the specific gravity of platinum is 2 1.45g/cm ㎡, which is much larger than that of gold and silver, and the specific gravity of gold and silver are 19.3G/㎝3 and 10.5G/CM3 respectively, and they have extremely high melting points, reaching 6544. Secondly, it has excellent acid resistance (except that it can be dissolved by aqua regia at 70℃, it can be dissolved by alkali solution without other acids) and high temperature resistance (it cannot be deformed by heating). It is precisely because of these characteristics that 1795 used platinum in the metric system based on decimal system. These two samples can still be found in the BRETCUIL collection near Paris.
Platinum is not only used in jewelry making, but also widely used in industrial fields, the most famous of which is used in catalytic reactors. Platinum also plays an important role in the medical field. It is not affected by blood oxidation and has excellent conductivity. And is compatible with live tissues. Because of these characteristics, platinum is used in pacemakers. At present, more than 50,000 people live a healthy life with pacemakers. For them, platinum is a life-saving metal. In addition, platinum is also used in the fields of electronics and clean energy, petrochemical industry, glass and aerospace. The quality of lenses and optical fibers made of platinum is good, so platinum is also used in TV equipment, computer monitoring screens, liquid crystal displays and other products that cannot be listed, even including fertilizer.
The difference between platinum and similar metals
Platinum has a hardness of 4-4.5 and a relative density of 2 1.45. It is chemically stable and insoluble in ordinary acids.
Metal-saturated aluminum can't recover after inelastic deformation, and its relative density is much lower than that of platinum. Lead is 1 1.36 and aluminum is 2.7, which are about 1/2 and 1/8 of platinum respectively. Try the weight by hand and you will know the difference.
Although silver is silvery white, its relative density is 10.53, only platinum's 1/2. Moreover, it is low in hardness and inelastic, so a slight stroke with your nails will leave traces. It is easy to deform and difficult to recover, and the chemical properties of silver are unstable. It will dissolve in nitric acid and release oxygen dioxide gas. However, platinum is insoluble in nitric acid and can only be dissolved quickly in heated aqua regia. At room temperature, its dissolution rate is extremely slow, which is generally difficult to detect with the naked eye.
Platinum is a good catalyst. Using this characteristic, platinum can be quickly identified, and hydrogen peroxide reaction method is commonly used. The specific method is as follows: Take a little powder of special substance and put it in a plastic bottle filled with hydrogen peroxide (H2O2). If the platinum has just boiled, it will be bubbled with hydrogen peroxide immediately, and a large amount of oxygen will be decomposed. After the reaction, the platinum is still intact and can be recovered (only accelerating the decomposition); If it is other white metals, such as lead, silver and aluminum, there is no such reaction.
Maintenance of platinum ornaments
How to care for your beloved platinum jewelry and make it as bright as new? Here are some things to pay attention to.
1, when doing heavy or manual work such as housework cleaning and gardening. Please don't wear platinum ornaments.
2. When doing housework at home, don't let platinum jewelry be stained with grease or bleach, because grease will affect the luster of platinum, and bleach may cause spots on jewelry. Platinum jewelry can be stored separately in jewelry boxes or leather to prevent other jewelry from being scratched.
3. When wearing platinum jewelry, please don't touch other irritating chemicals. Although chemicals may be harmless to platinum, they may discolor diamonds or precious stones set in platinum.
4. When wearing jewelry, avoid wearing platinum jewelry and gold jewelry together, because the texture of gold is soft. If it rubs against platinum, the gold powder will be adsorbed on the platinum, which will make the platinum yellow and affect the purity and luster.
If you wear platinum jewelry often, you should clean it once a month, so as to keep the luster of platinum permanently. The cleaning method of platinum jewelry is the same as other precious jewelry. Use the jewelry cleaner sold in the market, or soak it in the solution of soap and warm water, then gently wipe it with a soft cloth, or go to a professional jewelry store to clean it, and adjust, correct the size, polish and clean the jewelry.
6. If there are scratches visible to the naked eye, please take the platinum jewelry to a qualified jewelry place for polishing. All precious metals may leave scratches, and platinum is no exception. However, scratches on platinum will only move the material, and the volume will not decrease. If there are scratches visible to the naked eye, please take the platinum jewelry to a qualified jewelry gallery for polishing.
7. As time goes by, a natural oxide layer will appear on the surface of platinum due to contact with air. If this happens, please take your platinum to a qualified jewelry store and let them re-polish it to produce an extremely bright effect.
8. If the platinum jewelry is inlaid with diamonds, it is best to send the platinum jewelry to a professional jewelry store for maintenance every year, and clean and maintain it in time, so that your platinum diamond jewelry will always emit beautiful and charming light.