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Properties of materials
Published in William Bolton, R.A. Higgins, Materials for Engineers and Technicians, 2020
When light is incident on a material it can be reflected, absorbed or transmitted. Materials that reflect or absorb and do not transmit visible light, i.e. wavelengths of electromagnetic radiation in the visible part of the spectrum, are called opaque. Those materials that transmit a little diffuse light are termed translucent whilst those that transmit light sufficiently well that you can see through them are termed transparent. A measure of the reflectivity of a material is the fraction or percentage of the light incident at an angle of incidence of 30° to the surface and reflected at an angle of reflection of 30°. A mirror would have a reflectivity of 100%; a black matt surface, less than 1%. A sheet of aluminium might have a reflectivity of 60%, whilst stainless steel would be about 70%.
Materials Engineering
Published in Quamrul H. Mazumder, Introduction to Engineering, 2018
Ceramic materials can be broadly divided into two categories based on whether they are crystalline or noncrystalline. Crystalline ceramic materials include products such as bricks, tiles, and porcelain objects. Noncrystalline ceramic materials are almost all glass of some type. Crystallinity affects other properties of ceramic materials, but its most obvious effect is on transparency. Ceramics tend to be totally transparent when they are either 100% noncrystalline or 100% crystalline. Hundred percent crystallinity occurs when the part is a single crystal, as in a crystal of quartz. Materials between 0% and 100% crystalline are translucent rather than transparent because the grain boundaries between crystals break up the transmission of light. The same is true for loose powder particles of ceramics. Titanium dioxide in the form of large single crystals is transparent, but in the form of submicron powders, it is so effective at blocking light that it is used as the active ingredient in some sunscreens.
Fenestration and the Sun
Published in Matt Fajkus, Dason Whitsett, Architectural Science and the Sun, 2018
Translucency is the property of allowing light to flow through a material while limiting vision. This is done by diffusing or scattering light, which obscures the view. Translucent materials also smooth out the variation between light and dark, generally softening the experience of light. As such, translucent materials are inherently more enigmatic than their transparent or opaque counterparts. In contemporary architecture, glass is the primary material used for translucency, although synthetic materials such as plastics have been on the rise in the early 21st century. Synthetic plastics include polycarbonate panels, which are composed as extruded cells of thick plastic surfaces.6 Translucency in glass is produced through various treatments, including etching, coating, or lamination methods. The quality of opaqueness can be achieved through a wide range of materials. For the sake of studying fenestration in this chapter, opaque or solid materials are considered the default or controlled variable, whereas openings are the element under consideration, particularly in the illuminance diagrams.
Seeing is believing: investigating the influence of transparency on consumers’ product perceptions and attitude
Published in Journal of Engineering Design, 2022
Transparency is a design characteristic that designers can use to embody a product (Ashby and Johnson 2002; Karana, Hekkert, and Kandachar 2009). Transparency refers to the physical property of transmitting light. When transparency is used in product designs, transparency can be further divided into opaque, translucent and transparent based on the amount of light that can go through the surface (Ashby and Johnson 2002). Since opaque materials completely block light, internal technical details are invisible. Transparent materials allow all the light to pass by, while translucent materials enable part of the light to go through. As a result, consumers can see the internal components underneath transparent product covers clearly and see these details through translucent covers in a blurred way. For example, the transparent cover of Dyson handheld vacuum cleaner allows the consumers to observe how dust is collected (Lockton, Harrison, and Stanton 2010), whereas through translucent cover of the iMac users only have a blurry view of the internal components (Person and Snelders 2010).
The influence of yttria-stabilised zirconia and cerium oxide on the microstructural morphology and properties of a mica glass-ceramic for restorative dental materials
Published in Journal of Asian Ceramic Societies, 2021
Thapanee Srichumpong, Suphahud Pintasiri, Greg Heness, Cristina Leonelli, Ekarat Meechoowas, Noparat Thongpun, Chayada Teanchai, Kallaya Suputtamongkol, Duangrudee Chaysuwan
The color of a dental restorative material should have a yellow to the reddish-yellow gradient to be acceptable. Photographs, showing the difference in color and translucency, of the glass ceramics produced are shown in Figure 3. The translucency parameter indicates the reflected color difference, over white and black backgrounds, between materials with uniform thickness. It is considered to give the best measurement of human perception of translucency [30]. It is specified as one of the primary factors in controlling esthetics and used for the selection of materials for dental applications [31]. A high translucency parameter (TP) indicates that the material is less opaque. A material with a TP of 100 is considered transparent; a TP of 0 indicates that the material is opaque. In addition, the contrast ratio, another measure of translucency, was measured so as to compare results with the most recent literature [18]. The mean of contrast ratio and translucency parameter are reported in Table 2. After the heat treatment process, the color of the resulting glass-ceramic changed with the CeO2 additions producing a yellowish hue [32] and the addition of YSZ producing a whiter material [17,33] (Figure 3).
Fracture load of colored and non-colored high translucent zirconia three-unit fixed dental prosthesis frameworks
Published in Acta Biomaterialia Odontologica Scandinavica, 2018
Deyar Jallal Hadi Mahmood, Michael Braian, Abdul-Salam Khan, Armin Shabaz, Christel Larsson
Improved translucency is achieved by reducing porosity size and quantity, reducing impurities, keeping grain sizes small and uniform, and controlling types and amount of dopants [8,9]. To further enable a tooth-like appearance, coloring is necessary [5]. Previously, zirconia restorations were individualized using a staining technique. This method involves painting of the finished restoration and requires a final firing in a traditional dental ceramic furnace, similar to the painting of feldspathic porcelain. This is generally not regarded as coloring, since only the surface of the material is treated and the color effect is sensitive to adjustments such as occlusal grinding and normal wear. To achieve lasting coloring of zirconia, that permeates through the entire core of the material, two different methods may be used [10]. One method involves mixing of metal oxides into the powdered zirconia material before sintering, thus producing pre-colored green-stage blocks. Another method uses an infiltration technique where chloride solutions of rare earth elements are added to machined restorations at the pre-sintered green-stage [10].