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Precious stones
Published in Francis P. Gudyanga, Minerals in Africa, 2020
Sapphire is blue gemstone variety of the mineral corundum α-Al2O3. Trace amounts of iron, titanium, chromium, copper, or magnesium are responsible for the gemstone’s colours of blue, yellow, purple, orange, or green, respectively. The sapphire with pink or red tint is due to chromium impurities and it is called ruby which is the first variety of corundum discussed in 6.4. Padparadscha is the third gem-variety of corundum with a pinkish orange colour. Sapphire and rubies often occur together.
Introduction
Published in Roshan L. Aggarwal, Anant K. Ramdas, Physical Properties of Diamond and Sapphire, 2019
Roshan L. Aggarwal, Anant K. Ramdas
The density of sapphire is 3.98 g/cm3, resulting in an Al2O3 concentration of 1.762 × 1023 cm−3. The melting point of sapphire is 2303 K. The relative hardness of sapphire is 9 Mohs, which is the second-hardest material; diamond is the hardest known material, with a hardness of 10 Mohs. The bulk modulus of sapphire is 240 GPa (2.40 × 1012 dyn/cm2). Its shear modulus is 145 GPa (1.45 × 1012 dyn/cm2), and its Young's modulus is 345 GPa (3.45 × 1012 dyn/cm2).
MEMS Technologies
Published in Bogdan M. Wilamowski, J. David Irwin, Fundamentals of Industrial Electronics, 2018
Antonio Luque, José M. Quero, Carles Cané
Sapphire is a third option if MEMS devices require insulating and/or transparent substrates. Compared to glass and quartz, sapphire is stronger and wear resistant but much more expensive and difficult to etch. Sapphire is also compatible with CMOS manufacturing.
Effects of ultrasonic amplitude on sapphire ultrasonic vibration assisted chemical mechanical polishing by experimental and CFD method
Published in Mechanics of Advanced Materials and Structures, 2022
Mufang Zhou, Min Zhong, Wenhu Xu
Sapphire possesses excellent physical and chemical properties such as erosion resistance, thermal shock resistance, and high hardness [1]. It is widely accepted in aircraft fairings, integrated circuits, and semiconductor lighting. Dramatically, light-emitting diodes (LEDs), made from sapphire as the substrate, have been generally used all over the world [2–6]. The application of sapphire requires high surface quality [7], so the polishing process is regarded as extremely important [8, 9]. At present, surface planarization technologies generally include abrasive flow polishing (AFP), magnetorheological finishing (MRF), laser polishing (LP), chemical mechanical polishing (CMP), and other types [10–13]. While CMP is one of the most mainly applied and established technologies in the field of sapphire polishing [14], the first three polishing technologies have their limitations in terms of material applicability, processing efficiency, and processing quality [15–17].
Material removal in grinding sapphire wafers with brazed–diamond pellet plates
Published in Materials and Manufacturing Processes, 2019
Congfu Fang, Zhen Yan, Wenwen Deng, Liangchi Zhang
Sapphire has been widely used in the LED device industry for its high hardness and high temperature stability.[1–3] It has also been used in other fields of laser diodes and laser sources for its combination of high chemical resistance, mechanical characteristic and transparency.[4,5] Generally, high-quality sapphire wafers are manufactured by the processes of crystal growth (sapphire ingots), edge grinding, slicing, lapping, surface polishing and cleaning.[6,7] Among these processes, lapping is one of the most important processes controlling the thickness and flatness of the sapphire substrate, which has an obvious influence on the production quality, efficiency and cost.
Research on mechanism of ultrasonic-assisted nano-cutting of sapphire based on molecular dynamics
Published in Mechanics of Advanced Materials and Structures, 2023
Fei Zhou, Jinkai Xu, Wanfei Ren, Peng Yu, Huadong Yu
Sapphire has very good optical properties, good chemical stability, high strength, and wear resistance, and has been widely used in defense and consumer electronics fields [1–4]. In these applications, sapphire parts must meet nanoscale surface roughness, high dimensional accuracy, and tightly controlled subsurface defects. Ultrasonic vibration grinding technology is a combined processing method that improves grinding efficiency and surface quality by applying vibration to the workpiece, and meets the processing requirements of sapphire materials to achieve nano-scale surface roughness, low subsurface damage layer and high dimensional accuracy.