Material Science Engineering - Essay Example

Sapphire material Institution Affiliation Date MATERIAL SCIENCE ENGINEERING Introduction Sapphire (Al2O3) is a gemstone variety of mineral corundum and aluminium oxide which occur in alluvial deposits in the earth’s crust. The deposits exist in countries such as Afghanistan, Australia, China, India, Kenya, Nigeria and Pakistan. Sapphire is shinny like glass and is typically blue in color but can occur in color purple, orange, yellow, black, grey and green, and they can be colorless. It can also occur in more than one colour. Sapphires in a different color other than blue are called parti-colored or fancy sapphires. The other varieties of gemstones related to sapphire are rubies and padparadscha which are usually red and orange in colour. Sapphire- 9 is the third hardest mineral according to the Mohs scale and it comes after diamond and moissanite at 10 and 9.5 respectively. Commonly, sapphires that occur naturally are cut and polished into gemstones and worn in jewellery. Sapphires may be synthetically created for decorative and industrial use in large crystal boules. Sapphires are also applied to some non-ornaments, for example, infrared optical components, high durability windows, movement bearings and very thin electronic wafers used as insulating substrates of very unique solid-state electronics because of its remarkable hardness. The color, clarity, cut, size and overall quality are the factors that are used to determine the cost of Sapphires. A gemstone commands a greater price with its increasing intensity of the purity of its blue color. Above is the crystal structure of Sapphire. Mining Sapphires are mined from primary underground workings or alluvial deposits from the earth’s crust. Commercial extraction locations for sapphire and ruby include China, Australia, Burma, etc. Sapphires from various geographical areas may have distinctive appearances and chemical-impurity concentration and have a tendency to contain diverse types of microscopic inclusions. In light of this, Sapphires can be broadly categorized into three: classic metamorphic, non-classic metamorphic or magmatic, and classic magmatic. Sapphires from certain categories or specific area might be preferred in the market than others particularly classic metamorphic sapphires that have not experienced high temperatures or heat-treatment from Kashmir or Sri Lanka. Madagascar is the country leading in the production of sapphire from the deposits in Ilakaka town. Before the opening of the mines in Ilakaka, Australia was the largest world producer of sapphires. Andranondambo, a source of sapphires in southern Madagascar was discovered in 1991 and it was exploited but later abandoned after a few years later due to the extreme challenges of recovering sapphires in the bedrock. In the Jewel industry, the sapphire deposits of Kashmir are still outstanding in spite of the fact that the peak production from this region mostly took place in a moderately brief period towards the end of the nineteenth and mid-twentieth centuries. Kashmir-cause contributes seriously to the estimation of a sapphire, and most corundum of Kashmir source can be promptly distinguished by its trademark silky appearance and extraordinary hue. At present, the world record cost per-carat for sapphire at sale was accomplished by Sapphire from Kashmir in a ring, which sold for roughly $242,000 per carat (more than $6.74 million altogether, including purchaser's premium) in October 2015. Each sapphire mine delivers an extensive range of quality - and the place of origin is not an assurance of quality. Kashmir gets the most noteworthy premium for Sapphire in spite of the fact that countries such as Burma, Sri Lanka, and Madagascar likewise produces huge amounts of fine quality gems. Treatment Several methods may be used to treat Sapphires to enhance their clarity and color. It is basic practice to heat natural sapphires to enhance or improve color. This is achieved by heating the sapphires in heaters to temperatures somewhere around 500 and 2000 °C for a few hours, or by heating in a nitrogen-inadequate atmosphere oven for at least seven days. After heating, the stone turns out to be richer in color, yet loses a portion of the rutile inclusions (silk). At the point when high temperatures are utilized, the stone loses all silk and it turns out to be clear under magnification. The inclusion in natural stones is effortlessly observed with a gem dealer's loupe. Confirmation of sapphire and different gemstones being subjected to heating dates back to the Roman times. Un-heated natural stones are to some degree uncommon and will often be sold accompanied by an endorsement from an independent gemological lab verifying "no proof of heat treatment". Yogo sapphires some of the time do not need treating because their cornflower blue coloring is uniform and deep, they are by and largely free of the characteristic inclusions, and they have high uniform clarity. When Intergem Limited started promoting the Yogo in the 1980s as the world's exclusive guaranteed untreated sapphire, heat treatment was not generally unveiled; by 1982 the heat treatment turned into a main issue. Around then, 95% of all the world's sapphires were being heated to improve their common color. Intergem's advertising of guaranteed untreated Yogos set them against numerous in the jewel industry. To enhance and improve the color of sapphires the diffusion treatments are utilized to add impurities. Beryllium is diffused into a sapphire under extremely high heat, just below the melting point of the sapphire. At first (c. 2000) orange sapphires were made, albeit now the procedure has been advanced and many colors of sapphire are regularly treated with beryllium. The colored layer can be evacuated when stones chip or are repolished or refaceted, contingent upon the profundity of the impurity layer. Treated padparadschas might be exceptionally hard to identify, and many stones are affirmed by gemological labs e.g. AGTA). As per United States Federal Trade Commission rules, disclosure is required of any method of improvement that significantly affects the gem’s value. Several methods are available for treating sapphire. High temperatures treatment in a reducing or oxidizing environment (however without the use of whatever other added impurities) is generally used to enhance the color of sapphires, and this procedure is once in a while known as "heating only" in the gem trade. Conversely, be that as it may, heat treatment joined with the deliberate addition of certain particular impurities (e.g. beryllium, which are consumed into the crystal structure of the sapphire) is additionally normally performed, and this process can be known as "diffusion" in the gem industry. In any case, in spite of what the expressions "heating only" and "diffusion" may suggest, both of these classifications of treatment really include diffusion process. Color change sapphire An uncommon variety of natural sapphire, known as color-change sapphire, displays diverse colors in different light. Color change sapphires are blue in outside light and purple under radiant indoor light, or green to dark green in daylight and pink to rosy violet in incandescent light. Color change sapphires originate from a number of areas, including Thailand and Tanzania. The color-change impact is brought on by the interaction of the sapphire, which absorbs particular wavelengths of light, and the light-source, whose unearthly yield differs relying on the illuminant. Transition-metal impurities in the sapphire, for example, chromium and vanadium, are the reason for the color change. Particular synthetic color-change sapphires exhibit a matching color change to the natural gemstone alexandrite and they are in some cases showcased as "alexandrium" or "synthetic alexandrite". Be that as it may, the last term is a misnomer: synthetic color change sapphires are, in fact, not synthetic alexandrites yet rather alexandrite simulants. This is on account of genuine Alexandrite is a variety of chrysoberyl: not sapphire, but rather a totally unique mineral. Synthetic sapphire It is a single crystal form of corundum; Al2O3 also called alumina and single crystal Al2O3. Sapphire is aluminum oxide in the purest frame with no porosity or grain limits, making it hypothetically thick. The mix of favourable chemical, electrical, mechanical, optical, surface, thermal, and toughness properties make sapphire a favored material for high-performance system and design components. For different semiconductor applications, sapphire is the best decision in correlation with other engineered or synthetic single-crystals. 1. Properties I. Colour, texture and solubility II. Gravity and formation III. Melting and boiling points point IV. Hardness and solubility 2. Growth methods I. Kyropoulos method II. Stepanov method 3. Applications and uses I. Jewelry II. Glass windows III. Electronics IV. Armor applications V. Lamp glasses VI. Making circuits VII. As semiconductors 4. Advantages I. Transparency II. Hardness III. Resistant to scratch IV. Durability of products V. Resistant to thermal shock VI. Durability VII. Reflection and colour 5. Disadvantages I. High cost of manufacture II. Environment issues through emissions III. High cost of its products Conclusion Sapphire material occurs in the earth and has properties which make it applicable to a wide range of products. It has both positive and negative aspects associated with its process and products. However, more effort should be put towards the exploitation of mines and manufacture of sapphire material as it could lead to durable products improving the economy. Improved methods should be developed to enhance Sapphires purest hues. References Lu, Cong Da et al. "Material Removal Model Of Sapphire Substrate In Double-Side Lapping Process". Key Engineering Materials, 407-409, 2009, pp. 460-464. Trans Tech Publications, doi:10.4028/www.scientific.net/kem.407-409.460. 232U CONTENT OF SAPPHIRE MATERIAL. 1st ed., Upton, N.Y., Brookhaven National Laboratory, 2000,. Dobrovinskaya, E. R., Lytvynov, L. A., & Pishchik, V. (2009). Sapphire: material, manufacturing, applications. Springer Science & Business Media. Archer, D. G. (1993). Thermodynamic Properties of Synthetic Sapphire (α‐Al2O3), Standard Reference Material 720 and the Effect of Temperature‐Scale Differences on Thermodynamic Properties. Journal of physical and chemical reference data, 22(6), 1441-1453. Djurišić, A. B., Ng, A. M. C., & Chen, X. Y. (2010). ZnO nanostructures for optoelectronics: material properties and device applications. Progress in Quantum Electronics, 34(4), 191-259. LaBelle, H. E. (1980). EFG, the invention and application to sapphire growth. Journal of Crystal Growth, 50(1), 8-17. Jagadish, C., & Pearson, S. J. (Eds.). (2011). Zinc oxide bulk, thin films and nanostructures: processing, properties, and applications. Elsevier. Akselrod, M. S., & Bruni, F. J. (2012). Modern trends in crystal growth and new applications of sapphire. Journal of Crystal Growth, 360, 134-145. Read More