Impregnation / Infiltration Technology Introduction

I. Introduction of Impregnation / Infiltration

1. Definition of Impregnation / Infiltration

Infiltration, also known as Impregnation, saturation, infiltration.

Impregnation porous sealing is a micro porous (slit) penetration sealing process, the sealing medium (usually a low-viscosity liquid) through natural infiltration (ie, micro porous self-priming) pump vacuum, pressure and other methods to penetrate pores (slit), the gap is then filled. The sealing media solidified through natural (room temperature) cooling or heating method, and seal the gap.

2. Importance of Impregnation / Infiltration

Pores in the material is a common phenomenon, especially in casting and powder metallurgy manufacturing process, due to the residual porosity, crystal shrinkage and other reasons, inevitably cause large amount pores, trachoma, cracks, leaks. Micro porous is the hidden dangers of equipment, even non-pressure applications are possible to corrupt and shorten the parts’ service life, because liquid paint, electroplating solution, acid, etc. infiltrates into the casting work piece. Micro porous cause bubbles or uneven on the surface of paint, plating, or the like. Impregnated products’ scrap is almost zero, greatly saving the cost, fully use limited resources, and create a more perfect product.

3. Purpose and Function of Impregnation / Infiltration

A, To get anti-pressure, sealing performance

Seal the pores of products with impregnation solution.

B, To get anti-corrosion performance

Fill in linked or unlinked pores to prevent internal corrosion.

C, Pretreatment of synthesis processing

Fill in recessed inside seam to prevent discoloration, corrosion, peeling expansion.

D, To improve the cutting performance

Impregnation solution can play the role of lubricant to extend tool life, reduce machining costs.

E, To increase physical strength

Inner gap is reduced, and improve physical strength, can design the product  thinner.

F, To improve insulation

Closes the internal cavity and improve the protective effect of the resistance value.

4. Meaning of impregnation / infiltration

To maximize and fully use limited resources, turning waste into treasure, saving social energy, protect the natural environment.

II.Application Scope of Impregnation / Infiltration Technology

1. Impregnation / Infiltration of Casting Parts

The main purpose of Casting Parts Impregnation is leak-proof sealing, so that it can be used in hydraulic systems and gas systems. Such as automobile and tractor gearbox, fuel pumps, hydraulic valves, carburetors, fuel tanks, compressors and hydraulic components, closed aircraft instruments and electronic instrument covers, pneumatic components and pneumatic instrumentation.

Casting parts infiltration can also prevent internal corrosion and increase production. As we all know, internal corrosion of casting parts often start from the pores, when the pores are filled with impregnants, they can be prevented from penetrating corrosive liquids after curing, it has anti-corrosion effect.

In addition, casting parts infiltration is also used as pretreatment of plating, painting and other surface treatment. The infiltrant fills in the casting voids, to avoid plating solution absorption, to prevent bubbles and make plated surface smooth.

Impregnation can also be remedies for casting parts, die casting parts,when defects appear, such as porosity and pores. It promotes the casting products design thinner, lighter, saving material consumption.

2. Impregnation / Infiltration of Powder Metallurgy Parts

PM materials have excellent performance, so the liner accessories used on automobiles and tractors, valve guides, gears, cams, bearings, clutch plates, electric components, heat exchangers, cutting tools, tooling, molding and some corrosion resistance, high temperature oxidation and high temperature parts, are currently widely use powder metallurgy material.

Powder metallurgy raw material is metal powder (or a mixture of metal and non-metal powder), made of various types of work pieces after pressing and sintering. Characteristics of powder metallurgy parts are lots of pore network inside it, including very tiny air gaps between the powder fine metal particles,(approximately 15% of the entire volume of the work piece), even high-density powder metallurgy parts, such voids still exist. Therefore, powder metallurgy can not save liquid. Impregnation treatment can make the pores of powder metallurgy parts are completely filled with impregnating agent, to achieve a permanent seal, so that it can be used in hydraulic systems, for example, it can be manufactured into precise pump parts , compressor housing / shells and the like.

In addition, plating solution and cleaning agents will not be absorbed into the pores, and achieve smooth surface and corrosion-resistant parts, if powder metallurgy parts have done impregnation treatment before plating or other surface coating.

It must be noted, powder metallurgy should have impregnation process immediately after sintering, because pores are clean at the moment, can be easily and completely filled by impregnants. Powder metallurgy may also improve their cutting performance  after impregnation (after pores filled, interrupted cutting by tools and knives will become continuous cutting), and facilitate process control .

3. Impregnation / Infiltration of Electronic Device

Impregnated transformers, capacitors, motors and other electrical parts, their dielectric properties and insulation properties can increase. E.g., the stator assembly assembled with the housing / shell of the motor, form a single whole by impregnation. Porous are sealed after impregnating, and increase the strength and cooling effect, solves motors’ insulating properties reducing due to the vibration , the motor can still maintain good insulation performance in the humid environment after impregnation , and increase reliability and service life of the motor.

4.Impregnation / Infiltration of Mon-metallic Parts

Non-metallic materials, such as wood (sleepers, poles, etc.), ceramic and fiber-plastic composite materials, we use impregnation treatment to increase their life span and improve their water resistance properties. For example, large computer cooling system parts are generally made of fiberglass reinforced plastic, it can effectively sealed by impregnation, to prevent liquid to leak through a fine reinforcing fibers channels.

From the above, impregnation, infiltration sealing technology is widely applied in mechanical and electrical products, and porous material products.