【正文】 pure form crystal structure changes limit mechanical applications, however stabilised Zirconias produced by addition of Calcium, Magnesium or Ytrium Oxides can produce very high strength, hardness and particularly toughness. In addition the material has low thermal conductivity and is an ionic conductor above 600176。 C. This has lead to applications in oxygen sensors and high temperature fuel cells. Typical characteristics ? High temperature capabilty up to 2400176。 C ? High density ? High strength and fracture toughness ? High hardness and wear resistance ? Low thermal conductivity (20% that of Alumina) ? Good chemical resistance ? Ionic conductivity Typical applications ? Precision ball valve (balls and seats) ? High density grinding media ? Threadguides 導(dǎo)絲器 ? Cutting blades ? Medical prostheses ? Pump seals, valves and impellors ? Oxygen sensors ? Fuel cell membranes ? Radio frequency heating susceptors ? Metrology ponents Applications (structural materials,oxygen sensors and) ? orthopaedics[?????????????] 整形外科 : femoral[????????] 股骨頭 head, artificial knee, bone screws and plates, favored over UHMWPE due to superior wear resistance – dental: crowns and bridges ? made up about 25% of the total number of operations per year in Europe ? 8% of the hip implant procedures in USA. ? over 400,000 zirconia hip joint femoral heads have been implanted since 1985 until 2022 Compared to alumina ? partially stabilised zirconia (PSZ) – higher flexural strength – fracture toughness – better reliability – lower Young39。s modulus – ability to be polished to a superior surface finish – lower hardness 下圖為三種晶型的單位晶胞結(jié)構(gòu) ： ZrO2 三種晶胞參數(shù) 晶型 溫度 0C a b c ? 單斜 30 99o18′ 四方 1393 立方 2400 ZrO2結(jié)構(gòu)特征 純 ZrO2 在不同溫度下具有單斜 （ m） 、 四方 （ t） 、 立方 (c)三種不同晶型 ， 晶型轉(zhuǎn)化式為： 11700C 23700C 27150C 單斜相 四方相 立方相 液相 Stabilized zirconia ? FSZ fully stabilized zirconia ? PSZ partially stabilized zirconia ? TZP tetragonal zirconia polycrystalline ? stabilizer CaO MgO Y2O3 CeO2 To produce colored cubic zirconia, the following oxides can be added to achieve the following colors. Oxide Colors Produced Cerium oxide red, orange, yellow Copper oxide yellow, amber, brown Iron oxide yellow, amber, brown Nickel oxide yellow, amber, brown Praseodymium oxide yellow, amber, brown Titanium oxide yellow, amber, brown Erbium oxide pink Europium oxide pink Holmium oxide pink Chromium oxide green Manganese oxide green Vanadium oxide green Cobalt oxide lilac, violet Manganese oxide lilac, violet Neodymium oxide lilac, violet Excess yttrium oxide blue, green Cubic Zirconia history ? Cubic Zirconia was discovered in its natural state in 1937 by two German mineralogists, von Stackelberg and Chudoba. It was in a highly metamict zircon given to them by . Anderson. The zircon contained tiny crystals that were determined to be the cubic form of zirconium oxide by xray diffraction. The two mineralogists thought so little of their discovery that they did not even give it a name。 which is why it is still known by its scientific name, cubic zirconia. It wasn39。t until the 197039。s, however, that Soviet scientists learned how to grow the crystals in the laboratory. In 1977, it was first marketed under the trade name Djevalite. But CZ really took off in the 198039。s when Swarovski amp。 Co., a worldrenowned Australian producer of leaded crystal, began producing cubic zirconia for mass consumption. Cubic Zirconia Cubic Zirconia is well known as a substitute for diamond, due to its high hardness and great fire. But in recent years, it has established itself as a geous gem in its own right. CZ is a beautiful synthetic gemstone that is durable and inexpensive and now even es in any color of the rainbow, making it even more desirable. Cubic Zirconia ? Fully Stabilized Zirconias adopt the Fluorite structure CaF2, which is the structure of pure zirconia at high temperature. The lattice is facecentered cubic (fcc) and the space group is Fm3m. Zirconium cations occupy the positions (0,0,0) of the lattice and oxygen anions occupy the positions (1/4,1/4,1/4). Each Zr cation is surrounded by eight O ions which are contained in tetrahedrons formed by zirconium ions. The oxygen ions form a cubic sublattice of half the lattice parameter of the fcc cell. In a 3dimensional view, every alternate cube of oxygen ions has a zirconium ion in his center and one cube has only one edge in mon with another. Cubic Zirconia ? Cubic Zirconia is a cubic form of zirconium oxide that is created in a laboratory, thus it is not a mineral. However, it was found naturally occurring once at one site in the 193039。s, but has yet to be discovered since then. The mineral with the same chemical position as CZ, but in the monoclinic crystal system, is baddeleyite. Cubic Zirconia ? Cubic zirconia has a hardness of on Moh39。s Scale of Hardness and a white streak. It has a specific gravity between and , and a density between and . It is in the isometric crystal system with a 4/mbar32/m crystal class and a Fm3m space group. The refractive index of CZ is between and , which is very high. It