Combustion chemical vapor deposition

Flame coating, often Flammenpyrolytische coating (English Combustion Chemical Vapor Deposition, CCVD ) a process for the deposition of functional thin films at atmospheric pressure. The process belongs to the group of chemical vapor deposition ( engl. chemical vapor deposition, CVD).

History

In the 1980s, the first attempts to improve the adhesion of metal - polymer composites for dental ceramics by flame pyrolysis deposited silicon dioxide (SiO2) were carried out The derived Silicoater process provides a starting point in the development of CCVD processes dar. In the following period this method has been continuously developed and found new uses for by flame -applied SiO2. At this time, the term now commonly used " Pyrosil " for these layers was coined. In addition to the improvement of the adhesion include the broadband antireflection of flat glass surfaces or the effect as a barrier layer against various ions.

Process principle

In flame coating a combustible gas is added to a device suitable for producing the desired layer starting material ( precursor ). This is done in the gas control equipment, which ensure a precise dosage and optimum mixing. As precursors are primarily organometallic compounds (eg, silanes, siloxanes and various metal alkoxides such as titanium tetraisopropoxide ), less commonly salts such as metal acetates and nitrates or metal nanoparticles are used. The flame is moved a small distance above the substrate to be coated. Due to the high combustion energy form the precursors of highly reactive species, which connect firmly to the substrate surface. Since the substrates only briefly in contact with the flame, the thermal load is low; this is an advantage over CVD method, LPCVD and PECVD as where the substrates must generally have high temperatures.

Pros and Cons

As compared with other coating processes, the flame coating is particularly inexpensive, in part because no equipment is needed to produce and maintain a vacuum. There are many different versions, ranging from burners in the size of a pen to large manufacturing plants with more than one meter flame width, so this method is very flexible. The disadvantage, however, is that less layer materials as in some low-pressure processes can be deposited. The layers are also limited primarily to oxides; Exceptions are some precious metals such as silver, gold and platinum, which can be deposited metallic. It can only be generated layers, for which suitable precursors are available; However, this is the case for most metals.

Applications

• Silicon oxide layers are the layers most commonly produced. Fresh layers produced are very reactive and are therefore well suited as adhesion-promoting layers for coatings and adhesives. The liability can be further improved by additional use of silane -based coupling agents such as Glymo.
• Change in optical properties (eg, increase in transmission )
• Barrier protection, eg against gases such as O2 and mobile ions such as Na

• Chromogenic materials in "intelligent glazing"

• Semiconductor
• Part transparent, electrically conductive oxides ( engl. transparent conduction oxides TCO) such as aluminum zinc oxide ( AZO)

• Protective layer against mechanical influences (eg anti-scratch )

• Ingredient various transparent, electrically conductive oxides such as indium tin oxide ( ITO), fluorine tin oxide (FTO ), and antimony tin oxide (ATO)

• Photocatalytic layers

• High electrical conductivity
• Heat protective glazing
• Antibacterial coatings

• Protection against glass corrosion