Inorganic sacrificial materials

There are a variety of materials that can be used as sacrificial cores. Inorganic sacrificial materials include Si02 and metals such as aluminum, " titanium, and nickel. Polymers such as PI, PMMA, PC, and photoresist have also been used as sacrificial materials. After deposition of the cover film, removal of the sacrificial layer can be achieved by dissolution, etching, or thermal degradation. These removal methods each have benefits and drawbacks selection of the optimal approach is specific to particular combinations of substrate, sacrificial layer, and cover film 73, 3 Recently Whitesides and coworkers " implemented a fabrication method using water-soluble sacrificial cores. Poly(acrylic acid) and dextran proved to be effective sacrificial layers that could be dissolved in water or aqueous NaCl, for making metallic microstructures by nickel electrodeposition. 

Basically, it relies on incorporation of a thermally degradable material within a thermally stable matrix. The sacrificial material is removed usually by thermal degradation and volatilization to produce a porous structure. There are other techniques that will be shown later to remove the sacrificial material. One can use inorganic, organic, and hybrid materials in this approach. The availability of pore generators with different morphologies and the ability to vary the precursor ratios provide versatility and control not only the pore size and pore distribution but also the pore shape of the film. 

In conclusion, over 130 semiconductors are known to catalyze the photochemical water-splitting reaction according to eq 1 or either water oxidation or reduction in the presence of sacrificial agents. Even though the principle activitycontrolling factors in semiconductor-heterostructures have been identified, many aspects of the function of inorganic photocatalysts are still unclear. Most importantly, the molecular mechanism of water reduction and oxidation on the semiconductor surface has not yet been elucidated in sufficient detail. ° Many questions about charge transfer between semiconductor and cocatalysts, and its dependence on the structural and electronic features of the interface are still open. The effect of variable material preparations and surface impurities on the catalytic activity of semiconductors (e.g. sulfur and oxide on... 

A foundry core is a sacrificial aggregate that produces the interior configurationy or cavityy of a cast metal part The main component of this core is usually silica sand but other particulate inert materials have been used Sand is bonded by a core bindery which may be an organic resin composition such as a phenolicy furany alkyd or isocyanate Inorganic compositions of phosphates and silicates have also been used as core binders ... 

Considering the concept of sacrificial anode (cathodic protection), coatings that consist of high purity zinc dust dispersed in organic and inorganic vehicles have been designed in these materials, when applied in film form, there are dose contacts of the particles among themselves and with the base or metallic substrate to be protected. 

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