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Korundowa Mikrodermabrazja - Opinie, Skuteczność i Doświadczenia
Korund kosmetyczny – mikrodermabrazja
Domowa mikrodermabrazja i korund kosmetyczny to praktycznie 2 nierozerwalne rzeczy. Kryształki korundu mogą z powodzeniem zastąpić profesjonalną mikrodermabrazję wykonywaną w salonach kosmetycznych. Peeling korundem jest ostrzejszy od standardowego, sklepowego peelingu gruboziarnistego i niejednokrotnie słabszy od profesjonalnych peelingów dermatologicznych.
Korund w domu jest dobrym rozwiązaniem dla tych, którzy bardzo chcą oszczędzić czas i pieniądze, porównując standardową cenę zabiegu mikrodermabrazji (100 zł za zabieg) to cena korundu kosmetycznego jest śmiesznie niska i wynosi ok. 10 zł za 100 gram korundu.
Opłaca się? TAK! Ale pod warunkiem, że znamy sposób użycia korundu kosmetycznego!
Corundum
- In 1837, Marc Antoine Gaudin made the first synthetic rubies by reacting alumina at a high temperature with a small amount of chromium as a colourant. [15]
- In 1847, J. J. Ebelmen made white synthetic sapphires by reacting alumina in boric acid.
- In 1877, Frenic and Freil made crystal corundum from which small stones could be cut. Frimy and Auguste Verneuil manufactured artificial ruby by fusing
- BaF2 and
- Al2O3 with a little chromium at temperatures above 2,000 °C (3,630 °F).
- In 1903, Verneuil announced that he could produce synthetic rubies on a commercial scale using this flame fusion process. [16]
The Verneuil process allows the production of flawless single-crystal sapphire and ruby gems of much larger size than normally found in nature. It is also possible to grow gem-quality synthetic corundum by flux-growth and hydrothermal synthesis. Because of the simplicity of the methods involved in corundum synthesis, large quantities of these crystals have become available on the market at a fraction of the cost of natural stones. [17]
Structure and physical properties [ edit ]
Corundum crystallizes with trigonal symmetry in the space group R 3 c and has the lattice parameters a = 4.75 Å and c = 12.982 Å at standard conditions. The unit cell contains six formula units. [4] [21]
The toughness of corundum is sensitive to surface roughness [22] [23] and crystallographic orientation. [24] It may be 6–7 MPa·m 1/2 for synthetic crystals, [24] and around 4 MPa·m 1/2 for natural. [25]
In the lattice of corundum, the oxygen atoms form a slightly distorted hexagonal close packing, in which two-thirds of the octahedral sites between the oxygen ions are occupied by aluminium ions. [26] The absence of aluminium ions from one of the three sites breaks the symmetry of the hexagonal close packing, reducing the space group symmetry to R 3 c and the crystal class to trigonal. [27] The structure of corundum is sometimes described as a pseudohexagonal structure. [28]
The Young’s modulus of corundum (sapphire) has been reported by many different sources with values varying between 300-500 GPa, but a commonly cited value used for calculations is 345 GPa. [29] The Young’s modulus is temperature dependent, and has been reported in the [0001] direction as 435 GPa at 323 K and 386 GPa at 1,273 K. [29] The shear modulus of corundum is 145 GPa, [30] and the bulk modulus is 240 GPa. [30]
Single crystal corundum fibers have potential applications in high temperature composites, and the Young’s modulus is highly dependent on the crystallographic orientation along the fiber axis. The fiber exhibits a max modulus of 461 GPa when the crystallographic c-axis [0001] is aligned with the fiber axis, and minimum moduli ~373 GPa when a direction 45° away from the c-axis is aligned with the fiber axis. [31]
The hardness of corundum measured by indentation at low loads of 1-2 N has been reported as 22-23 GPa [32] in major crystallographic planes: (0001) (basal plane), (10 1 0) (rhombohedral plane), (11 2 0) (prismatic plane), and (10 1 2). The hardness can drop significantly under high indentation loads. The drop with respect to load varies with the crystallographic plane due to the difference in crack resistance and propagation between directions. One extreme case is seen in the (0001) plane, where the hardness under high load (~1kN) is nearly half the value under low load (1-2 N). [32]