Chemical Surface Coating

The creation of such a network of attached silanes on a substrate by consecutive single-step adsorptions is in fact a Chemical Surface Coating (CSC). 

In the early 90 s, a new technique, Chemical Surface Coating (CSC) was developed by Vansant, Gillis-D Hamers, Van Der Voort and Vrancken, in order to create thin ceramic layers on a substrate by successive chemical modifications. The principles and developments of this technique are the subject of a separate section of this book (cfr. chapter 14). 

Therefore, in the early 1990 s a new coating technique has been developed by Gillis-D Hamers, Van Der Voort, Vrancken and Vansant.1,2,3 This new procedure is called Chemical Surface Coating (CSC) and is presented in figure 14.1. 

In the gas-phase modification of Chemical Surface Coating, the inorganic substrate is subjected to subsequent, single step, one component reactions. This process is repeated in a cyclic way. The reaction temperatures are very low, usually room temperature. In this way, the ceramic precursor is built. Its thickness is a function of the number of CSC cycles involved. A CSC cycle is a subsequent modification of the substrate with 2 gases. Finally, the ceramic precursor is converted towards a ceramic coating by a thermal treatment. 

In the liquid phase modification of Chemical Surface Coating, the treatment of gas 1 and gas 2 are replaced by a modification with e.g. an organosilane. In this case, the thickness of the ceramic precursor can be controlled by varying the amount of water in the reaction phase. When the reaction occurs in an aqueous phase, thick multilayers are created. Reaction circumstances, totally free of water, will yield a monolayer. 

The main characteristics of the Chemical Surface Coating technique can be summarized as follows ... 

For this reason, Chemical Surface Coating can be considered as a fundamental technique to study complex reaction mechanisms by decomposing them into a number of simple steps. 

The CSC precursor build-up has been studied after modification of the silica gel surface from the gas phase. This gas phase modification involves the deposition of one molecular layer at the time. For thicker coatings, a cyclic procedure is needed. Liquid phase modification of the silica surface may also yield valuable ceramic precursors. The precursor molecular structure and layer thickness is controlled by other parameters compared to gas phase procedures. Parameters such as reaction solvent, silane concentrations and presence of water are of primal importance. Those have been discussed in detail in chapter 9. In this chapter, the application of silica modified with aminosilanes, will be discussed. The aminopropylsilica is used as a prototype compound for the production of ceramics by liquid phase chemical surface coating. 

Silicon (oxy)carbide coatings by Chemical Surface Coating... 

Pascal Van Der Voort is presently senior research assistant at the Laboratory of Inorganic Chemistry (University of Antwerp). He was granted the title of Doctor in Sciences for his pioneering work on Chemical Surface Coating. After that, Dr. Van Der Voort stayed strongly involved in the research on chemically modified oxide surfaces and their application as ceramics and catalysts. 

Karl C. Vrancken is presently a researcher at the Laboratory of Inorganic Chemistry (University of Antwerp). In this position he substantiated the development of the Chemical Surface Coating method. In his young career as a Doctor in Sciences, he gained full expertise in organosilane chemistry. His current work is concerned with surface modifications and advanced materials preparation. 

In the period mentioned above the most known world centers of the studies of chemical reactions on silica and alumina surfaces were USSR, Germany, Bulgaria. But since 1977 after the patent [26] had been published and later in the eightieth as well as at present the number of publications in this field has increased in various countries [27-39]. It should be noted, that some authors use another names for the synthesis like the ML method for example, atomic layer epitaxy (ALE) [30], chemical surface coating [31], grafting [32],elementary surface reactions of CVD method [33]. 

Synthesis of a Polysilazane Coating on a Silica Gel via Chemical Surface Coating Comparing Liquid- and Gas-Phase Chlorosilylations... 

C) is 4 X 10" . In the USA, this type of ware is termed Chemical Porcelain . Chemical Surface Coating (CSC). This low-temperature chemical modification technique has three stages activation of the substrate formation of the new ceramic precursor by chemical action heat treatment to convert the new precursor into a new ceramic coating. 

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