PTFE coatings (Polytetrafluoroethylene) are high molecular fluorocarbon solids. Among all the fluoropolymers, they have the highest temperature resistance.
They are also the most resistant to chemicals due to the strong carbon-fluoride bonds.
PTFE coatings also have a low friction coefficient, a high resistance to abrasion and corrosion, plus they are nonstick.
It is these and other properties that make them ideal for industrial coating applications. Let us expound more on PTFE coatings.
History of PTFE coatings
In April 1938, Roy J Plunkett discovered the PTFE coating. He was working in New Jersey for DuPont to make a chlorofluorocarbon refrigerant.
However, the tetrafluoroethylene gas he was using stopped flowing from the pressure bottle before the bottle weight dropped to signal it was empty.
He became curious and sawed the bottle apart only to find the interior coated with a slippery waxy white material. After analysis, he found the material to be polymerized perfluoroethylene.
Roy J Plunkett’s new substance was patented by Kinetic Chemicals in 1941 and registered as the Teflon trademark in 1945.
In 1948 DuPont, the founder of Kinetic Chemicals produced over 2 million pounds of PTFE for use in the Manhattan project as valves and seals coating.
By 1961, PTFE was used in producing kitchenware with nonstick coating. Subsequently, in 1990, PTFE was refined by radiation crosslinking to make it reusable and easy to regrind.
How is the PTFE coating made?
Polytetrafluoroethylene is made through 2 phases or, rather, a series of chemical reactions.
The ingredients involved in the reactions are chloroform, fluorspar, water, and hydrofluoric acid, which are heated in a chemical reaction chamber at 1094-1652°F.
Series of reactions
- Combination of chloroform (trichloromethane), fluorspar, and hydrofluoric in a process known as pyrolysis to yield TFE (Tetrafluoroethylene). But, TFE is highly flammable and can be risky to transport; therefore, it is synthesized at the PTFE production site.
- Polymerization of TFE into PTFE in the presence of water and catalysts such as ammonium persulfate or disuccinic acid peroxide.
How is the PTFE coating applied?
A substrate can be coated with PTFE manually or automatically, like in a conveyer using an HVLP spray gun.
After coating, the substrate is cured in a special oven at temperatures between 725- 800 °F for perfect appearance and excellent coating properties.
Application and uses of PTFE coating
PTFE has found lots of applications, particularly in industries.
Now, some of the equipment manufactured in many industries tend to deteriorate and damage due to corrosion, wear and tear.
However, equipment and apparatus with PTFE coatings reduce the damage that increases the life span and even safety to consumers.
The coatings have a low coefficient of friction which has lubricating effects in machinery.
For example, machine manufacturers use PTFE coatings on surfaces that slide against each other like slide plates, bearings, and gears.
The coatings are also common in hydraulic and fuel lines.
It makes it possible for the fuel or hydraulic fluid to continue flowing in higher altitudes and colder temperatures due to its low friction coefficient.
Industries that produce chemicals like gasoline, hydrochloric acid, Sulphuric acid, and sodium hydroxide use PTFE coatings in their machines.
The non-corrosive properties of the coatings make the machines immune to the chemicals, increasing their lifespan.
1. High-tech tools and parts
Manufacturers also use PTFE coatings in high tech tools and parts. The coatings are used for wiring in cables and connectors that are used in aircraft and computers.
The coatings are used in making plugs and jacks. This is owed to their high heat resistance, insulating properties, and dielectric properties.
2. Nonstick cookware
Due to its non-stick properties, PTFE coatings are used to produce nonstick cookware such as cooking pots and frying pans.
The coatings have more benefits other than the non-stick properties. They are highly resistant to heat with a melting point of up to 620 ºF, a temperature that isn’t used in cooking stoves. So, the cookware can be used at high temperatures with little degradation.
Additionally, the hydrophobic and nonstick properties of the coatings prevent liquids and food from adhering to the surfaces. This makes it easier to clean up the cookware.
Moreover, the inert chemical properties of the coatings mean they are safer for use in cookware.
3. Medical applications
In the medical field, PTFE coatings are used in devices and surgical tools like forceps, sutures, and catheters, etc. The coatings have a low friction coefficient, are nonstick and resistant to chemical corrosion, abrasion, and high temperatures.
In fact, infectious microorganisms do not adhere to the surfaces of the PTFE coatings. In other words, using them in medical and surgical tools reduces instances of infection acquired from the hospital settings.
Some medical and surgical tools can even be reused on patients after cleaning and sterilization with reduced risks of metal contamination.
The inert chemical properties of the coating are also commonly used to make artificial body parts like dental fillings.
4. Food processing
PTFE coatings are also widely used in food production industries for the same reasons they are used in cookware. The non-stick properties prevent the food product from sticking to the surfaces.
Resistance to high temperature prevents the food surface contact with the PTFE coatings from degrading. Again, the non-corrosive properties of the cooking prevent the food surfaces from eroding due to contact with food ingredients such as salt.
The inert chemical properties of the coating prevent it from picking up smells and flavors from the surrounding.
The surfaces are also excellent in that they do not react with chemicals and sanitizers that are used to clean food production lines, a feat that also translates to longer life spans.
There is also the aspect of environmental and human safety with using PTFE coatings in food processing industries.
In a nutshell, PTFE coatings are used widely industrially owing to their excellent properties under heat and chemicals.
From making excellent insulators, vehicles, and machine parts to producing high-quality cookware and much more. The coatings are also excellent in coating medical devices and apparatus like surgical tools, thus enhancing patient and user safety.
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