AEROXIDE® fumed alumina and AEROSIL® fumed silica are suited to perform various functions in illuminants that are difficult to duplicate with other materials. They are indispensable in modern lighting applications (e.g. compact fluorescent lamps, fluorescent tube lamps, LEDs).
AEROSIL® and AEROXIDE® products function in lighting applications:
as inorganic binders
as mercury diffusion barriers
as light diffusers
AEROXIDE® Alu C and AEROXIDE® Alu 130 as a binder in the phosphor layer ensure maximum performance. Applied as protective layer they deliver increased lifetime of a fluorescent lamp, which results in lower energy costs and less frequent replacements. VP* Disp. W 905 L is a developmental fumed alumina dispersion tailored to provide an optimal protective layer coating for fluorescent lamps and to save the complex process step of dispersing small particles in water at our customer’s site.
The adhesion of fluorescent materials to one another and to the glass surface is inherently poor because both, the fluorescent materials and the glass surface usually have a negative surface charge. Evonik’s AEROXIDE® fumed alumina product range has a positive surface charge and therefore functions effectively as an inorganic binder.
Without AEROXIDE® fumed alumina, small amounts of mercury continuously penetrate into the layer of fluorescent material and into the glass tube. This causes the tube to turn gray over time, which affects efficiency as well as light yield: First, the mercury that is required to produce the UV radiation is reduced. Secondly, as the tube turns gray, it absorbs more of the visible light, increasing the transformation of light into heat. A layer of AEROXIDE® fumed aluminum oxide acts as an effective mercury barrier.
A diffused light source is not only less harsh and more pleasant to the eyes but also achieves a more homogeneous illumination. Since many years AEROSIL® products such as AEROSIL® 200 have been employed in incandescent lamps to make the frosty layer inside the bulb. In modern LED lamps, AEROSIL® and AEROXIDE® products can be applied as diffusion particles inside the LED silicone lens.
AEROXIDE® Alu C
AEROXIDE® Alu 130
BET surface area
100 ± 15 m2/g
130 ± 20 m2/g
200 ± 25 m2/g
pH (in 4% dispersion)
4.5 - 5.5
4.4 - 5.4
3.7 - 4.5
VP* Disp. W 905 L
5 ± 1 wt. %
≤ 100 mPas
3.0 - 5.0
Mean aggregate size (d-50 value)**
< 0.2 µm
* Developmental products are labeled with the VP designation. Commercialization depends on market response.
** The data represents typical values (no product specification)