Development of Crystal

With the improvement of people's living standard, domestic popular crystal (crystal) heat, Chanel, Dior and other brand-name fashion with SWAROVSKI crystal crystal decoration, jewelry, ornaments, but also by the exhibits to fashion, shoes and hats, watches. Some famous foreign architectural glass enterprises also produce crystal flat glass and crystal glass construction products, and apply it to high-grade buildings. Overseas, there have been crystal clubs long ago, there are a large number of crystal fans. There are cities and towns such as Crystal Palace Crystal City, specializing in crystal glass processing. But the non academic journals at home and abroad, the enterprise website, promotional materials called crystal crystal, according to the dictionary of Chinese translated as crystal, and not on the traditional quartz crystal (quartzcrystal), K9 optical glass with more than some domestic processing crystal city crystal ball, crystal crafts, crystal glass is crystal glass. Quartz crystal is still the traditional quartz crystal in Jiangsu, East China Sea and so on. The crystal glass has a long history, the ancient times because of glass raw material impurities, the melting temperature is not high, no glass melting is good, there are a lot of unmelted sand, bubbles and other defects, and raw materials of iron and manganese, titanium and other colored metal ions, the glass is often opaque or semi transparent. By thirteenth Century, people in Venice fused colorless, transparent glass with less impurities in quartzite and Levant of sodium containing ash. In fifteenth Century, the quality of more raw materials was further improved, with the Ticino River pure quartz sand and ash water solution recrystallization in soda ash, has significantly improved the transparency of glass than in the past, and the crystal is similar, so named Cristallo, is a kind of sodium calcium crystal, the composition range (mass fraction), [1]SiO270.0%~71.5% Al2O30.8%~1.31%, CaO4.07%~4.72%, MgO1.47%~1.66%, K2O2.84%~4.55%, Na2O15.2%~16.8%, Fe2O30.25%~0.51%, MnO0.26%~0.51%, SO30.19%~0.31%, Cl0.62%~0.92%, P2O50.15%~0.24%, Fe2O3, MnO as the component of impurities in mineral raw materials, Cl and P2O5 were impurities in soda ash. Sodium calcium crystal glass composition and modern glass composition are similar, the content of K2O+Na2O is relatively high, the content of CaO+MgO is relatively low, the fusible glass, suitable for manual operation. After thirteenth Century, Bohemia (Bohemian) in Bohemia (Bohemia, now part of Czech) and Silesia (Silsia) region to establish a dozen glass factory, in addition to the high quality quartz sand as raw material, also containing potassium carbonate wood ash, such as beech forest (beethforests) wood for the introduction of alkali oxides the raw material, made of transparent glass and high refractive index, also known as crystal glass (crystalex), the literature in order to distinguish the Venice crystal glass, called Bohemia crystal (BohemiaCrystalex), used for forest wood as raw material, so it is also called the forest glass (ForextGlass). Bohemian crystal glass is potassium calcium component, containing SiO275%~77%, CaO5%~6% and K2O15%~17%, glass refractive index nD is 1.48~1.49, this system is called potassium calcium crystal glass. Later, in order to improve performance, add Na2O and a little B2O3 in composition, renamed the potassium sodium calcium crystal glass, crystal glass composition of this type of current production in Czech (mass fraction) of SiO275.5%, B2O30.2%, CaO6%, K2O4.8%, Na2O12.8%. Potassium calcium and potassium sodium crystal glass mainly from 90km from Prague with Bohr (Nov? Bor) town, technical index of the products: density 2.444g/cm3, refractive index nD (20 C) was 1.50002 and the average dispersion (20 DEG C) is 830 * 10-5, linear expansion coefficient is 89.1 * 10-7 C -1, resistance acid (according to the standard of ISO719 0.01mol/L HCl at 98 DEG C after the erosion of glass surface is 1.98mg/dm2, weight per unit area) the liquidus temperature of 950 [2]. In the Middle Ages the crystal glass manufacturing technology of Bohemia gradually spread to central and Western Europe, British and French glass factories use Bohemia potassium calcium and potassium sodium calcium glass composition, melting temperature is relatively high, need good wood for fuel, cut down a large number of forests, in 1615 the British crown banned using high-quality wood as fuel glass factory, influence glass factory. In 1670 the British Ravenscroft found PbO in the glass composition, not only reduces the viscosity and melting temperature of the glass, the glass is easy to melt, forming material of long, convenient, and glass gloss increased, more clear, and easy to cut, it will lead glass into production, called leadcrystal. The refractive index, dispersion and density of lead crystal are higher than those of sodium calcium crystal (Cristallo) and potassium calcium crystal (crystalex). The melting, forming and grinding properties of lead crystal are better than those of sodium, calcium and potassium calcium crystals. Therefore, they have been popularized.