Fluorooxidation
Fluorooxidation (F/O) is a surface pretreatment that is conducted inline at ambient conditions. While the science of using Fluorine (F2) gas for surface modification has been well understood for more than 50 years, it has not been widely accepted primarily because of the safety concerns in using Fluorine gas. The significant breakthrough in fluorooxidation as a commercially viable pretreatment for yielding high-strength adhesion bonding is its safe gas processing and eco-friendly neutralization. Small scale, computer-controlled electrolytic cells enable the Fluorine gas to be used safely at low concentrations and low pressures.
An advantage of F/O is its capability to effectively treat large and small surface areas of complex geometry (remote/isolated regions) ranging in size from capillary to large diameter tubes and housings. F/O is an oxidation process, unlike flame and electrical discharge pretreatments which are glow discharge gas phase surface oxidation plasmas. Compared to chamber pressurized RF cold gas plasma treatment, F/O is conducted at ambient conditions. During the F/O processing, a substrate surface is exposed to Fluorine gas and other reactive and non-reactive gases in a controlled chamber. Similar to gas phase surface oxidation processes, oxygen-containing functional groups, such as hydroxyl, carbonyl and carboxyl are created making the surface wettable and very polar. These chemical and physical mechanisms are necessary to achieve strong adhesive bonds.
F/O is used to surface modify ultra-high molecular weight polyethylene (UHMW PE) and high density polyethylene (HDPE) powders to impart a hydrophilic (water-wettable) surface to these normally hydrophobic materials. This change in compatibility, as well as adhesive bonding capability, enables these treated powders to be sold as performance additives for use in polyurethanes, epoxies, rubbers, unsaturated polyesters and even water-borne systems.
F/O treatment is long-lasting and frequently permanent. This is because the treatment chemistry can penetrate considerably deeper than other surface preparation processes. The longevity is important because it avoids the need to use treated items quickly and enables treated substrates to be inventoried for long time periods. Contrary to common belief, use of highly reactive chemicals is actually environmentally friendly. This is because highly reactive chemicals are readily and essentially quantitatively neutralized because they are so reactive. Processes that use unreactive chemicals are some of the most difficult to scrub or neutralize. The spent solid state scrubbing medium used to neutralize the F/O process has commercial value for other manufacturing firms and is sold as a reagent.
Frequently Asked Questions
What is fluorooxidation?
Fluorooxidation (F/O) is a surface pretreatment run inline at ambient conditions in which the substrate is exposed to fluorine gas together with other reactive and non-reactive gases in a controlled chamber. Oxygen-containing functional groups -- hydroxyl, carbonyl and carboxyl -- are created on the surface, making it wettable and highly polar, which is what enables strong adhesive bonds.
If fluorine chemistry has been understood for 50 years, why is fluorooxidation only now practical?
Because of the safety concerns around handling fluorine gas, which kept it from wide acceptance rather than any doubt about the science. The breakthrough that made it commercially viable is safe gas processing with eco-friendly neutralization: small-scale, computer-controlled electrolytic cells let the fluorine be generated and used at low concentrations and low pressures.
How long does fluorooxidation treatment last?
F/O treatment is long-lasting and frequently permanent, because the treatment chemistry penetrates considerably deeper than other surface preparation processes. That longevity is the practical advantage: treated parts do not have to be used quickly and can be inventoried for long periods, unlike parts treated by gas-phase plasma processes.
What geometries can fluorooxidation treat?
It treats large and small surface areas of complex geometry, including remote and isolated regions, across sizes ranging from capillary tubes to large-diameter tubes and housings. This reach into areas a line-of-sight process cannot see is one of its distinguishing characteristics.
Is fluorooxidation environmentally damaging?
Contrary to common belief, using highly reactive chemistry is environmentally favorable here. Highly reactive chemicals are readily and essentially quantitatively neutralized precisely because they are so reactive; it is the unreactive chemicals that are hardest to scrub. The spent solid-state scrubbing medium from the F/O process has commercial value and is sold on as a reagent.
What is fluorooxidation used for besides bonding parts?
It is used to surface modify UHMW PE and HDPE powders, giving these normally hydrophobic materials a hydrophilic, water-wettable surface. The treated powders are then sold as performance additives for polyurethanes, epoxies, rubbers, unsaturated polyesters and even water-borne systems.
