What is Vacuum Impregnation?

Sealant impregnation fills the voids andmicroporosity in a wide variety of materials. A micropore is a tiny defect inthe component, which has the potential to turn into a large and expensiveproblem. By cleaning and then sealing the surface of the component in a vacuum,these small defects can be filled, prolonging the lifespan of the treatedpiece.

There are many reasons to use surfaceimpregnation:

· To prevent leaks
· To reduce moistureentrapment
· To improve integrity ofwelds on cast iron and aluminium substrates
· To reclaim expensivecastings and fabrications that would fail due to leakage
· To prevent”blow-out” of entrapped gases during plating or painting processes

What is the process?
During the impregnation process, componentsare packed carefully into designated baskets. The baskets are then lowered intoa vacuum chamber containing Luoke resin sealant. The chamber has its pressurelowered to a vacuum greater than 10 mbar. This draws air out of any porositythat has a leak path to the surface of the component. After a suitable vacuumis achieved and held for a specified time, the air is allowed back into thechamber forcing resin sealant into the previously evacuated pores. Thecomponents are drained thoroughly and then excess sealant on the externalsurfaces and in holes is washed off with cold water. The basket is thenimmersed in hot water to cure the sealant and prevent porosity.

The impregnation process involves five keystages:

· Part preparation
· Impregnation
· Drain
· Cold wash
· Hot cure

Part Preparation
Before impregnation, porosity within thecomponent must be completely clean and dry. While this is achievable through aseparate pre-process, Luoke offers modules for aqueous washing and vacuumdrying that can be integrated into the system.

What does impregnation achieve?

· Outstanding void fillingcapacity due to low shrinkage during polymerisation
· Optimised viscosity andcapillary action for fast deep penetration of micro porosity
· Tough and flexibleattributes to provide resistance to chemical, temperature and vibration
· Excellent adhesion tocavity walls ensuring a permanent seal
· Stability at operatingtemperatures between -50°Cand +150°C (+200°C intermittent)

The Luoke impregnation process will treatany size of component using sealant formulations designed to ensure fullcompatibility with various substrates. These include: Aluminium, Magnesium,Cast Iron & Steel, Carbon Fibre Composites, GRP Mouldings, Plastics andWood, however can work with customer’s materials to diversify a sealant to helpthem cope with porosity in their components.

When the impregnation process is complete,the component can be put to use without further treatment. The process does notdamage or distort the impregnated component. Treated parts are resistant tocoolants, lubricants, solvents and most corrosive acids. It will continue tofunction in a wide range of continuous temperatures.