UNIVERSITÀ DEGLI STUDI DI LECCE Corso di laurea in Ingegneria dei Materiali A.A. 2001/2002 Scienza e Tecnologia dei Materiali Ceramici. SELF-CLEANING GLASS and ELECTROCHROMIC GLASS. Professore Dott. Antonio Licciulli. Studente Daniela Lisi. SELF-CLEANING GLASS. SUMMARY. HISTORY.
Density: 4,2 g/cc
Refractive Index: 2,76
Density: 4,2 g/cc
Refractive Index: 2,52
TO REALIZE SELF-CLEANING MATERIAL SURFACES THERE ARE THREE PRINCIPAL WAYS:
Hydrophobic materials ("water hating") have little or no tendency to adsorb water and water tends to "bead" on their surfaces (i.e., discrete droplets). Hydrophobic materials possess low surface tension values and lack active groups in their surface chemistry for formation of "hydrogen-bonds" with water.
For a given droplet on a solid surface: the contact angle is a measurement of the angle formed between the surface of a solid and the line tangent to the droplet radius from the point of contact with the solid.
The LOTUS EFFECT
WHAT IS IT?
The acceleration of the rate of a photoreaction by the presence of a catalyst (semiconductor particle).
WHAT IS a SEMICONDUCTOR SOLID?
HOW DOES PHOTOCATALYTIC SEMICONDUCTOR WORK?
OXIDATION-REDUCTION REACTION ON THE SURFACE OF TIO2
(room temperature, atmospheric pressure).
converted to water and CO2.
reactions are produced.
TiO2 AS PHOTOCATALYST
IT IS COMPETITIVE BECAUSE:
Also called hydrophilic, is a characteristic of materials exhibiting an affinity for water. Hydrophilic literally means "water-loving" and such materials readily adsorb water. The surface chemistry allows these materials to be wetted forming a water film or coating on their surface.
MECHANISM OF PHOTO-INDUCED HYDROPHILICITY
TIME DIPENDENCE OF THE WATER CONTACT ANGLE IN AMBIENT ATMOSPHERE
SCHEMATIC DIAGRAM OF SUPER-HYDROPHILICITY MECHANISM
It changes the view of glazing from a FIXED element to a DYNAMIC one.
Optical switching materials can be used for windows where optical and thermal modulation is required.
THE PURPOSE IS:
to control the flow of light and heat into and out of window, according to an energy management scheme.
THE BASIC PROPERTY IS:
a large change in optical properties upon a change in either light intensity, spectral composition, heat, electrical field, or injected charge.
This optical change results in a transformation from highly transmitting state to a partly reflecting or absorbing state, either totally or partly over the solar spectrum.
Electrochromic windows change the light transmittance, transparency, or shading of windows in response to an environmental signal.
HOW ECDs WORK?
HOW ECDs ARE MADE?
A voltage applied across the transparent conducting oxide layers causes hydrogen or lithium anions (A+) to be injected into the electrochromic layers.
continuous range in solar and optical transmittance, reflectance, and absorbance between bleached and coloured states;
ELECTROCHROMIC MATERIAL PERFORMANCE OBJECTIVES ARE: