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Processing of Optical Materials
Published in Solomon Musikant, Optical Materials, 2020
Fused quartz is made by melting very high purity crystalline quartz such as Brazilian quartz which is mined. Quartz from surface sands is rarely as pure as the mined Brazilian quarts, which has metal impurity levels in the few tens parts-per-million range. However, for very exotic applications even this is not good enough, and synthetic amorphous silica glass is made by a number of chemical vapor deposition (CVD) processes. The CVD process starts with purified silicon tetrachloride and yields an amorphous silica glass with about 1 ppm of metallic impurities. This material can be fused into a product known as fused silica. Thus fused quartz and fused silica are distinctly different products.
Materials for Optical Systems
Published in Anees Ahmad, Handbook of Optomechanical Engineering, 2018
There is a difference between fused silica and fused quartz, or quartzglass.20 Fused silica is manufactured by the pyrolytic decomposition of reactive gases and usually has high water content and no metallic impurities. Fused quartz is made by fusing crystalline quartz to form a glass. Fused quartz has some level of metallic impurities that can cause UV fluorescence, and the water content depends on the firing method. Fused quartz can have some granularity, a residual of the original quartz crystal structure. Properties of these silica materials depend to some extent on their thermal history, and therefore nominally identical materials will have slightly different n and α from different manufacturers.
Reinforcement Materials
Published in Martin W. Jawitz, Michael J. Jawitz, Materials for Rigid and Flexible Printed Wiring Boards, 2018
Martin W. Jawitz, Michael J. Jawitz
The term quartz refers solely to fused quartz as opposed to crystalline quartz. Fused quartz is an inorganic glass, composed principally of fused silica (SiO2). Historically, the main reason for using quartz as a laminate material is a CTE in the xy-plane that is lower than that of E-glass and matches more closely to that of the ceramic chip carrier, allowing for higher solder joint reliability during thermal cycling. The selection of quartz is otherwise only justified when the finished laminate Dk (~3.7, especially at X-band) and a very low Df (~0.005) are of primary concern; that makes this material very attractive for some microwave applications such as radomes and microwave polarizers. Any incremental improvement in the CTE due to the quartz fabric has to be viewed in light of higher cost and processing difficulties, in particular drilling, as the quartz is very abrasive. The chemical composition of the quartz fibers is given in Table 1.1 and the physical properties are shown in Table 1.2.
Sulfidation kinetics of titanium and Ti-6Al-4V with elemental sulfur
Published in Corrosion Engineering, Science and Technology, 2023
Subbarao Raikar, Steven DiGregorio, Owen J. Hildreth
A 254 µm thick Ti64 sheet (TMS Titanium) and a 200 µm thick titanium sheet (Futt) were cut into 14 mm × 10 mm pieces using a sheet metal shearing machine. The Ti64 and titanium sheet pieces were cleaned in an ultrasonic bath with acetone, methanol, and isopropyl alcohol for 5 min. Next, the sheet pieces were blow-dried with compressed N2 gas (General Air). All the cleaned sheet pieces were placed individually in a fused quartz tube (13X16, Technical Glass) of length 300 mm with 25 mg of sulfur flakes (≥99.99% trace metals basis, Sigma Aldrich). The fused quartz tube was then purged with Ar (99.999%, General Air), evacuated three times, and sealed with a hydrogen–oxygen flame in the evacuated state. The length of the fused quartz was 300 mm to prevent an explosion due to excessive internal pressure in the tube. The samples encapsulated in the fused quartz tubes were placed in a box furnace (Carbolite 201) after the temperature was equilibrated for sulfidation. Supplementary Information Figure S1 shows a representative image of the encapsulated samples. After four hours of sulfidation, the encapsulated samples in the furnace were quenched in water to arrest the sulfidation reaction. The samples were sulfidized in steps of 100°C from 650°C to 950°C for 4 h to fit the linearised metal consumption model. Finally, the sulfidized sheet samples were removed from the fused quartz tube for analysis. The sulfide scales formed on the sheet samples were fragile and easily broke away when the samples were removed from the tube.
Impact damage of the surface layer of α-quartz amorphized by the Ar+ ions implantation
Published in Radiation Effects and Defects in Solids, 2022
Alexandre Chmel, Sergey Eronko, Igor Shcherbakov
The mechanical energy transforms into light due to the generation of non-bridged oxygen hole centers (NBOHC) [≡Si–O–] in crashed SiO2 (9). The decomposition of the crystal long-range order with accumulating the multiplicity of point defects takes place also in ion-implanted or neutron-irradiated α-SiO2. So restructured matter of α-SiO2 acquired a name of the ‘amorphized SiO2’ (10,11). At the same time, though the irradiated particles decompose the long-range order in crystals, a term of ‘amorphized quartz’ is not a synonym for designating amorphous (vitreous) SiO2 (12). The annealed fused quartz retains its disordered structure, while the amorphized one transforms into a canonical crystal under the appropriate heat treatment (13).
Anisotropic Radiation-Induced Changes in Type 316L Stainless Steel Rods Built by Laser Additive Manufacturing
Published in Nuclear Technology, 2019
Jordan A. Evans, Scott A. Anderson, Eric J. Faierson, Delia Perez-Nunez, Sean M. McDeavitt
Nanoindentation was performed using a Hysitron TI 950 Triboindenter equipped with a Hyistron standard transducer and a diamond Berkovich tip. The system was calibrated by indenting a fused quartz standard prior to testing. In order to ensure that measurements in the irradiated regions were unaffected by the undamaged subsurface, indentation could not be performed at depths below 10% the ion beam depth (about 150 nm) in accordance with standards.37 Therefore, nanoindentation was performed at depths of 75, 100, and 125 nm in both irradiated (inside the dotted box in Fig. 2) and unirradiated (outside the dotted box in Fig. 2) regions. Recalling that irradiation was performed at the 316L peak swelling temperature of 475°C, indentation of unirradiated regions was performed after irradiation in order to ensure that the unirradiated/irradiated regions had the same thermal histories. Indents were performed in locations far (i.e., >75 μm) from any physical or irradiation boundaries. For statistical purposes, each indent was repeated 20 times in 2 × 10 arrays with a 3-µm pitch using the “5 second loading, 2 second hold, 5 second unloading” load function. Drift during nanoindentation was less than ±0.05 nm·s−1.