Market Leader in Fluoride Ion Cleaning, Chemical Vapor Deposition and Vapor Phase Coating Systems

Fluoride Ion Cleaning Systems

Fluoride Ion Cleaning (FIC), synonymous with Hydrogen Fluoride (HF) Ion Cleaning, has been proven to be a highly effective process for the removal of deeply embedded oxides from superalloys containing significant amounts of aluminum and titanium.

Top Loading FIC System

APPLICATIONS

Gas turbines require regular overhaul to ensure optimum performance and efficiency. Hot section engine components are subject to damage and deterioration from one or more of the following:

• Sulphidation
  

• Oxidation
  

• Hot Corrosion
  

• Fatigue
  

• Foreign Object Damage (FOD)
  

Repairs require the addition of new material applied by welding and/or brazing. The FIC process is the best cleaning process for the removal of deeply imbedded oxides prior to weld or braze repair.

HF Delivery System

THE FIC PROCESS

The process results from the reaction of fluorine with various oxides that are formed on the parts. At temperatures greater than 1750° F (950° C), the fluorine reacts with oxides that have formed on the surface of the turbine components, converts them to fluorides, and allows for their removal. This leaves behind a clean surface as a preparation step for vacuum brazing and other repair processes. The chemical reactions are illustrated by the following:

6 HF + Al₂O₃ = 2 AlF₃ + 3 H₂O

4 HF + TiO₂ = TiF₄ + 2 H₂O

6 HF + Cr₂O₃ = 3 H₂O + 2 CrF₂ + F₂

In addition to the removal of oxides from the surface and within cracks, surface depletion of elements such as titanium and aluminum also occurs which enhances brazeability by removing oxide reformers. These reactions are illustrated by the following:

6 HF + 2Al = 2AlF₃ + 3H₂

8 HF + 2Ti = 2TiF₄ + 4H₂

FIC Fixtures

FEATURES

The significant feature of our systems is the generation of the fluorine containing atmosphere independent from the component temperature inside the reactor (retort). This process is referred to as Dynamic Fluoride Ion Cleaning (DFIC). The reaction temperature, concentration of fluorine, pressure level, and duration are all independently controlled variables. This state of the art process has been proven to be more effective and repeatable than older processes based on the decomposition of fluorine containing compounds.

A unique feature of our systems is the ability to perform the FIC process at sub atmospheric pressure from 100 to 650 Torr (133 to 867 Millibar) while at processing temperature. This process is referred to as dual vacuum. The dual vacuum process has been proven to be the most effective method of cleaning heavily oxidized parts. This is accomplished by creating a vacuum on both the retort and the furnace (required to prevent collapse of the retort while at temperature from the forces of the vacuum). The dual vacuum process has been found to be extremely effective in cleaning cooling channels, small cracks and blind holes. By changing the pressure level in the retort, HF gas is forced into cooling channels, small cracks and blind holes. Another benefit of the dual vacuum process is that it utilizes significantly less HF than the atmospheric FIC process.

Bell Type FIC System

FIC FURNACE SYSTEM

A typical FIC system is comprised of an electrically heated furnace; a reaction chamber (retort); vacuum system; hydrogen and argon delivery system; gaseous HF delivery system; fume neutralization system (scrubber) -- all controlled by a microprocessor based automated control system.

The furnace systems can be either bell type (a moveable furnace that gets lowered over the fixtured parts) or a top loading system (fixtured parts get lowered into a stationary furnace).