PVD coating technology – acronym for Physical Vapor Deposition – gives aluminum exceptional technical and aesthetic features. The PVD coating process takes place inside a vacuum chamber: the very pure materials that will make up the coating are brought to evaporation and are subsequently deposited on the aluminum surface in carefully controlled nanometric layers. The treatment is very sophisticated: it can achieve exceptional light reflection performance, which reaches over 98%, and a selective absorption capacity of over 90%.
Thanks to a dedicated plant, which was built in 2006 in Bernburg (Germany), Almeco has developed an extensive experience in PDV coating. The plant is equipped with a sophisticated air-to-air coil coating line for continuous treatment of metal strips in vacuum. The line is composed by several chambers using different technologies, so that it can deposit a broad variety of complex multilayer structures.
Thanks to this approach, Almeco has developed a wide range of reflective and absorber surfaces with PVD coating for applications in several industries.
Optical coatings offer the opportunity to tune the reflectance of the aluminum surface in various ways. It is possible to enhance or suppress certain parts of the light spectrum, creating outstanding performances or vibrant colors.
The aluminum subjected to PVD coating treatment is ideal in the Lighting and solar energy sectors. But not only: let’s see five outstanding – and sometimes unexpected – applications.
1. Renewable energies: TiNOX® and vega®SP
The core of any solar thermal panel is the absorber, which converts the energy in the form of solar radiation into heat. The more efficient is the absorber, the greater the heat produced by the panel.
TiNOX® is the selective absorber PVD coating developed by Almeco which ensures a high absorption of sunlight and low emissions of thermal radiation. The combination of these durable characteristics allows an efficient use of solar energy and minimum heat loss at the same time. The absorber surface has also been optimised for outdoor use without any additional transparent cover (TiNOX®Outdoor) or for the use in harsh environmental conditions (TiNOX®Robust).
Still in the renewable energy sector, PVD-coated aluminum can become a key element for the construction of CPV (Concentrated Photovoltaic) photovoltaic systems. Almeco has develop vega®SP, a range of products based on pre-anodized aluminium strip, PVD coated with a multi-layer reflection stack. In vega®SP optimum reflectance of the solar spectral range is obtained applying carefully controlled reflection enhancing layers, using continuous PVD vacuum coating technology. These materials give reflection values of over 95% and 98% respectively on the vacuum coated strip.
The surfaces treated with PVD coating can become the fundamental components of a CSP (Concentrated Solar Power) system: the concentrator mirrors, light and unbreakable, efficiently convey solar radiation by reflecting it on the absorbing collectors, allowing the system to convert sunlight into useful energy.
Even large sheets of aluminum with a mirror finish can be precisely shaped and curved to the required geometry.
2. Outdoor and indoor lighting: vega®95 and vega®98
The aluminum surfaces that are pre-anodised and then coated through PVD techniques, sometimes treated to make the material more ductile, find application not just in indoor fixtures, but also in the field of outdoor, street and stadium lighting or as the main component of floodlights.
vega®95 and vega®98 combine the proven quality of the aluminium anodising processes with PVD technology to significantly improves the reflector optical performance and increases its efficiency up to 20% compared to the already high levels of anodised aluminium, thanks to its extraordinary reflectance. The PVD vacuum deposition use in vega®95 guarantees a minimum reflectance of 95% to this product, whose finishes range from glossy to diffusing. vega®98 is also available in a variety of patterns and finishes, ranging from gloss to diffuse. This product guarantees a lighting reflectance of at least 98% with both isotropic and anisotropic distribution.
Vega®98 surfaces are also used to direct natural light in indoor environments in a controlled manner, daylighting systems, with excellent color rendering and features capable of ensuring high visual comfort.
3. Greenhouse agricolture: vega®greeN
Due to its reflection characteristics, PVD aluminum is also a valuable ally in the horticultural field, where it can be applied to improve the performance of HPS (high pressure sodium) lamps and LED reflectors. Almeco has developed two products for these applications: vega®greeN and vega®green LED.
Vega®greeN results from the optimization of vega®95 to increase the total reflection of the surface from orange to red and far-red range of the spectrum to enhance the efficiency up to more 4%, if compared to standard 95% TR materials.
It can enhance the spectrum emission of the sources without fearing the humidity and heat typical of these environments. Applied to LED sources, vega®green LED can promote the luxuriant growth of crops inside vertical farms, because it reflects uniformly all required wavelengths of light.
4. Sanification: vega®UV-C
Ultraviolet light offers a quick and effective solution to sterilize and sanitize environments and objects.
The UV-C band (the wavelengths between 200 nm and 280 nm) is considered “UV germicidal” because the radiation is absorbed by the DNA and RNA of micro-organisms, such as viruses and bacteria, modifying their structure and hindering their reproduction.
vega®UV-C high-reflective aluminum surface increases the effectiveness of the UV system through reflections. With a sufficiently powerful radiation intensity, the UV-C is a very reliable, fast, and environmentally friendly disinfection method because it doesn’t require the use of chemical agents.
5. Other special applications
vega®UV is widely used in curing processes, where the energetic UV radiation allows to initiate photochemical reactions. vega®UV portfolio also includes vega®UV-A – which is suitable for suntan lamps, in forensic applications and in the evaluation of gems and art pieces – and vega®UV-B, which finds application in the medical field, for example in light sources for the treatment of psoriasis and other skin conditions.