There has been considerable interest in the cost effective synthesis of iron oxidesas an additive in construction materials and coatings. Iron oxide has a number of applications, but of particlular interest is as a coloring and anti-corrosion agent in construction materials and coatings. Iron oxide materials are used as pigments in black, red, orange, brown and yellow colors. A majority of commercially produced iron oxide pigments are used in coloring concrete, brick, tile and other construction materials. Red iron oxide pigments are also used in steel and automobile primers to reduce corrosion of the metal itself. Iron oxide pigments also improve the temperature resistance of coatings, allowing coatings to be more weather resistant.
While the bulk forms of iron oxide pigments, micron size and larger, have been used for millenia, creation of nano-sized iron oxide pigments, particularly in the 2 nm to 10 nm range has allowed for transparent applications. Iron oxide nanoparticles have very good UV blocking capabilities, making these nanoparticles ideal for glass applications ranging from glass coatings to cunglasses. They also allow for better dispersion in paints and coatings, especially in high gloss and automotive applications.
Iron oxide metal nanoparticles are created via a number of methods. the particles can be produced by chemical and nahydrous recipitation, whereby the materials are synthesized as precipitates in solution. The Sol-Gel or forced hydrolysis process allows for precise fabrication of collodial dispersed iron oxides of very specific composition. This proces also allows for fabrication at low temperatures, reducing energy consumption and allowing for applications involving temperature intolerant materials.
Thin films and coatings can be applied through aerosol or vaporization techniques like chemical vapor deposition or laser pyrolysis for high production rates. Electrochemical processes such as electroplating allow for the creation of coatings through electrolysis. Finally, sonochemical techniques use ultrasound waves to create new iron oxide enhanced materials with novel properties.
Iron oxides are used as pigment and coating additives to aesthetically enhance, strengthen and protect concrete and other materials. For example, iron (III) oxide is used to fill the pores in concrete and reinforce the structure so calcium chloride and magnesium chloride will not easily penetrate the concrete. This extends the longevity of the concrete.
Adding iron oxide nanoparticles to building materials and industrial coatings has resulted in stronger and more durable construction materials. These particles reinforce conrete, increase the longevity of structural materials, decreases the replacement costs of materials and infrastructure and reduces ultimately reduces the carbon footprint of infrastructure development and material use.
The health and ecological risks associated with iron oxide nanoparticles are uncertain and ambiguous at best. These particles can and do have toxic effects from both direct and indirect sources, but the dose, specific toxicity, and overall adverse effects are dependent on the application. Additionally, the specific risks are dependent on the specific cell type involved. Exposure of these cells to the iron oxide nanoparticles also depends on the application. These particles likely range in toxicity from biologically benign/inert to cytotoxic depending on application and exposure conditions.