Materials & Chemicals
Method of Treating Surfaces to Create Extremely Hard Carbon Films
WARF: P03169US
Inventors: Ferencz Denes, Sorin Manolache, Luis Emilio Cruz-Barba
The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing a new method of producing extremely hard carbon films.
Overview
The extreme characteristics of diamond, including hardness, wear-resistance, biocompatibility, optical transparency and electric insulating properties, make it very useful for a range of industrial applications. In the past, production of synthetic diamond required extremely high temperatures and pressures. Now, however, diamond-like carbon films can be made at low pressures and relatively low temperatures by techniques such as chemical vapor deposition (CVD).
During conventional CVD and plasma-enhanced CVD processes, activated molecular fragments resulting from a specific mixture of hydrocarbons and acetylene are deposited onto the surface of a substrate held at temperatures of 600 to 900° Celsius. These temperatures are required to shift the reaction equilibrium toward the formation of diamond structures; however, they also limit the technique’s utility because temperature-sensitive substrates, such as polymers and low-melting point alloys, can’t be treated in this way.
During conventional CVD and plasma-enhanced CVD processes, activated molecular fragments resulting from a specific mixture of hydrocarbons and acetylene are deposited onto the surface of a substrate held at temperatures of 600 to 900° Celsius. These temperatures are required to shift the reaction equilibrium toward the formation of diamond structures; however, they also limit the technique’s utility because temperature-sensitive substrates, such as polymers and low-melting point alloys, can’t be treated in this way.
The Invention
UW-Madison researchers have developed a new method of producing extremely hard carbon films at room temperature and under low pressure. The method involves exposing an organic polymer on a surface to a sulfur hexafluoride-containing plasma. The researchers have shown this treatment converts pre-deposited, poly-acrylic thin layers on surfaces into carbon films with hardness values greater than nine. For comparison, diamond-like coatings have a hardness of 10.
Applications
- Production of extremely hard carbon films for industrial applications
Key Benefits
- Produces carbon films of extreme hardness (hardness values greater than nine) and low friction
- Plasma reaction proceeds at room temperature and low pressure (50 to 500 mTorr).
- Results in films of greater than 90 atomic percent carbon
- Treatment takes as little as five minutes
- Can confer extreme heat-, scratch- and wear-resistance on virtually any material, including glass, quartz, metal, plastic and silicon (provided they are coated first with the appropriate organic polymer)
- Can be used to treat items of varying shapes and sizes, including windows, medical implants and eyeglass and other lenses
- Unlike CVD techniques, which produce films composed of networks of small diamond crystals, this technique creates carbon films of high uniformity and smoothness.
- Plasma treatment can take place in any suitable plasma reactor.