Details of connector lubricant, corrosion inhibitor and anti-corrosion protectant application

 

connector lubricant, contact lubricant & corrosion inhibitor

AX7-C connector lubricant  

Connectors are the weak link

Electrical connector contact failure due to some form of corrosion is a primary cause of equipment failure. The application of a state-of-the-art connector lubricant formulation, like AX7-C, will largely eliminate this problem.

Contacts fail because of their imperfections

Contact metal surfaces are not really smooth. At the sub-microscopic level, even polished contact surfaces are like mountain ranges being forced into each other, peak to peak. These peaks are called asperities and this surface roughness is referred to as the rugosity of the surface. The contact's current flows between the asperities on the contact's mating faces. The greater the pressure on the contact the more asperities are pressed together and the lower will be the contact's resistance. However that increased pressure increases the force needed to bring the contacts together and cannot be increased without limit. So there are always gaps between the asperities. I.e, there are valleys between the peaks. These valleys “catch” the asperities as the contact's mating surfaces move past each other. That catching tears the metal, creates friction and exposes bare metal to corrosion. E.g. from Oxygen and other compounds in the air and environment. The valleys also provide reservoirs for moisture and debris like corrosion byproducts (e.g.,oxides and salts) and other contaminants to accumulate. The accumulated materials often then corrode the underlying metal.

Why Gold plating isn't enough

The so-called Noble metal platings (e.g., Gold and Palladium) have a high immunity to corrosion due to their naturally impenetrable surface films. However, in their practical application on contacts, there are shortcomings that allow them to fail.

Noble metals are very expensive and, usually, mechanically weak. Therefore, Noble metals are almost always plated, as thinly as possible (to reduce cost) over a cheaper, harder barrier metal like Nickel. The thinner coatings increase the porosity of the noble metal plating. The inevitable pits and voids of this porosity and grain structure defects in the plated noble metal coating, exposes the non noble barrier metal and non noble contact metal beneath it (e.g., brass, copper, phosphor-bronze, etc.) to corrosion. So corrosion of the base/barrier metals takes place due to porosity and plating defects in the noble metal plating. This can result in contact failure even in the extremely expensive military grade noble metal contacts using the best practices.

The fallibility of contact plating is one of the reasons why the military and many other critical applications seek the protection of a premium connector lubricant like AX7-C. In fact, some of the most expensive connectors already have a connector lubricant applied during manufacture. With AX7-C, you can achieve the highest protection on all your connectors and at-risk metals.

About corrosion

In the most general sense, corrosion occurs because a metal is not adequately protected from the corrosive materials (e.g., oxidizer like oxygen or reducer like hydrogen sulfide) and solvents like water in its environment. All metals chemically react to some degree with their environment forming a surface layer, i.e., a film of reacted material. This film passivates the metal against further corrosion, however all metal films are not equal. The so-called Noble metals (e.g., Gold and Palladium) naturally form films that are very impenetrable to continued corrosion and are considered to be passivated or non reactive. Iron for example does not have such an impervious film and is must be painted or otherwise coated to protect it from ongoing corrosion.

Fretting corrosion

Fretting corrosion is caused when fresh metal surfaces are exposed to a corrosive compound in the environment due to the inevitable micro-motions that take place between the contact's mating surfaces (e.g., pin to socket). These micro motions are inevitable and even occur with mechanical stresses, e.g., from repetitive mechanical flexing or temperature cycling of the connector. The motions are greater when a connector is subjected to any vibration such as from fans, motors, and motion (air, sea, land). With each motion cycle, the metal's natural protective passivation top layer is scraped off exposing bare metal to create a new passivation layer and further corrosion. This cycle repeats with each motion of the contact's metal faces. Eventually, the buildup of corrosion products between the contact's faces increases the contact's resistance even to the point of creating an open circuit. This resistance increase can directly cause circuit problems or indirectly due to resistance heating of the contact causing the contact to fail from overheating.

What AX7-C does

When applied, AX7-C bonds to the metal surface displacing corrosion compounds and so preventing them from reaching the metal. Therefore corrosion can't take place. Because metal has a higher affinity for AX7-C than water and most other compounds, the AX7-C application will “self-heal” as freshly exposed metal grabs AX7-C from around the exposed area. AX7-C is now acting as the passivating film for the metal.

Thus fretting and other forms of corrosion are prevented because bare metal gets AX7-C between it and the compounds that create corrosion.

Contents

A proprietary, non-hazardous, active ingredient blend in a patented, stabilized n-Propyl Bromide solvent carrier (~90% by weight). Contains no silicones, PPE's or petroleum distillates.

AX7-C uses several active ingredients including a proprietary hydrocarbon blend unlike connector lubricants based on PPE's (polyphenyl ethers). While polyphenyl ethers can be excellent connector lubricants especially where an extremely low vapor pressure and very low outgassing are needed, AX7-C is formulated to be better at water displacement and removal. It is also easier to apply in most common applications and is somewhat lower in cost.

 

Back to AX7-C connector lubricant.

 

 

Connector Lubricant