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Antistiction Layers for Nano Imprinting Lithography
Published in Ahmed Busnaina, Nanomanufacturing HANDBOOK, 2017
Spin coating is a well-known and traditional method for fabrication of thin films on a rotating flat substrate by dropping a liquid. It is very simple but highly reliable and reproducible.27 Spin coating involves the acceleration of a liquid puddle on a rotating substrate. The coating materials are usually supplied to the center of the substrate either manually or by a robotic arm. The physics behind spin coating involves a balance between centrifugal forces controlled by spin speed and viscous forces that are determined by solvent viscosity of polymer. The spin-coating technique consists of six basic stages: dispensing, low-speed spreading, high-speed coating, and baking, as shown in Figure 9.4. Some variable process parameters are involved in spin coating such as solution viscosity, solid content, angular speed, and spinning time. The film-forming process is primarily driven by two independent parameters, viscosity and spin speed. For thicker films, high material viscosity, low spin speed, and a short spin time are needed. Sometimes multiple coatings are preferred for a thicker film. However, it is hard to make a uniform coating on patterned surfaces with spin coating and up to 98% of process materials could be wasted. In addition, it is hard to fabricate a film thickness below 100 nm.28,29
Eco Requirements for Lubricant Additives and Base Stocks
Published in Leslie R. Rudnick, Lubricant Additives, 2017
In various applications, the lubricant can be in contact with parts made of yellow metals, typically copper, or with dissolved metal contaminants. As copper compounds catalytically decompose peroxides generating radicals, these metal species are very efficient pro-oxidatives and need to be deactivated. Dissolved copper ions are deactivated with chelating agents, whereas the metal parts are protected and deactivated with film-forming metal-passivating agents. The advantage of film- forming agents is the fact that they prevent the progressive oxidation of the metal surface, which would release copper ions to the fluid. Complexing agents, on the contrary, could even promote the transfer of copper ions from the metal surface into the fluid. A typical example of a chelating agent would be disalicyliden-propylene-diamine, in which film-forming agents are very often derivatives of benzotriazol [82]. Both groups of metal deactivators are used only in very low treat rates, below 0.1%, and are active in all suitable base fluids used for the formulation of biolubricants. A critical property of some metal deactivators is the low solubility; especially when PAO is used as a base fluid, this property must be carefully checked.
Antioxidant Finishing Enabled Packaging for Improved Shelf Life of Food
Published in Mohd Yusuf, Shafat Ahmad Khan, Biomaterials in Food Packaging, 2022
Meenu Aggarwal, Anjali Gupta, Vanita Sapra, Meenakshi Singhal, Nisha Saini
Environment-friendly films can be produced by either wet processing or dry processing. In wet processing method, film forming ability can be produced from materials, which must be soluble in a solvent like water and alcohol, further combined with plasticizers, antimicrobial agents, and colors or flavors in this process. The dry method does not include solvent dispersal as it depends on intrinsic thermoplastic features of some biopolymers [12].
Extending the Life of Historic Concrete Arch Bridges: State of the Art
Published in Structural Engineering International, 2019
Arne P. Johnson, Gary J. Klein, John S. Lawler
Since freeze-thaw damage and reinforcing steel corrosion are moisture-driven mechanisms, addressing uncontrolled drainage and leaking expansion joints is the first step in slowing this deterioration. However, precipitation and condensation may still be sufficient to promote deterioration. Depending on historic preservation implications (see below), ingress of moisture can be further limited by application of surface treatments, such as penetrating sealers or film-forming coatings. Clear penetrating sealers (e.g. silane sealers) may help repel water from concrete surfaces and in fine cracks, but do not bridge or fill larger cracks. High performance, film-forming coatings provide a higher level of protection and can bridge cracks. Acrylic- or silicone-based coatings are more vapor permeable than other concrete coatings, allowing the structure to dry.