Corrosion and Environmental Testing

Corrosion occurs because a metal is unstable in its environment. This may be as simple as the formation of an oxide layer on metallic aluminum, which happens almost instantly in air, or a much more complex situation at the base of a pit in a piece of copper or even stainless steel tubing. Corrosion can be promoted by various components of the local environment, ranging from atmospheric constituents to stray electrical fields, even to colonies of bacteria. MATCO has decades of experience locating and identifying these complex elusive conditions. Testing of paints and coatings for their corrosion and environmental resistance can be done according to established ASTM or NACE procedures. Or if standard tests do not exist for your applications, MATCO can design a special procedure to meet the demands of your particular situation.

MATCO has an array of environmental chambers for use in corrosion and environmental testing. These include QUV, Salt spray/fog and humidity chambers, each of which is described in more detail in the section on Corrosion in the Category Bar at the top of the Web page. The chambers can be used individually or in series, with constant or periodic fluctuations in all of the conditions, including UV light exposure, temperature and moisture/humidity.

An additional capability, almost unique with MATCO, is the mixed-flowing-gas system. This is also described in more detail on the Corrosion category page, but essentially it allows mimicking of atmospheric pollution exposures, along with temperature and relative humidity control. Thus, for example, if an electronic circuit board is going to be used in a Kraft paper mill, and the manufacturer wants to check to see if the conformal coating on the board will resist the sulfur in the atmosphere, that condition can be created in the MFG test chamber. This particular form of testing is becoming more and more important as circuit boards become smaller and smaller and short-circuiting more likely from corrosion.

For example, in a recent case it was found that copper whiskers were growing out from beneath the tinned leads of integrated circuits, then corroding in the sulfur-rich atmosphere to form black copper sulfides roses. With only a little more time, these roses would make contact with one another and shut down the system. An example of one of these is shown at the top of this page. The manufacturer had to add a conformal coating to protect his product from the harsh atmospheric pollutants which were attacking the printed circuit boards.