At-Line Analysis For The Metal Industry: SPECTRO PHOENIX II Monitors The Thickness Of Conversion Coatings

August 28, 2007

Application Report: PHOENIX II measures Hydrosilicon, Phosphorous, Zirconium, Titanium, Vanadium and Chromium on Aluminim and Steel Sheets
Kleve, August 2007 – To extend the life of aluminum and steel, metal sheets are covered with a passivation or conversion coating that protects the metal from corrosion and oxidation and serves as a bonding agent to facilitate varnishing and painting. The thickness of the coating must be carefully controlled during processing to ensure uniform quality. SPECTRO, one of the world’s leading manufacturers of X-ray fluorescence analysis (XRF) equipment, has developed a new application for the metal industry for at-line measurement of hydro-silicon, phosphorous, zirconium, titanium, vanadium and chromium coatings using a robust XRF instrument. The detection limit for phosphating, for example, is only 13 g/m².  SPECTRO documents the new application in an application report that  describes the measurement arrangement and results from several test series. The report is available free-of-charge at

Until several years ago, chromating was nearly the only conversion coating used. However, due to the harmfulness of hexavalent chromium and the restrictions placed on its use within the framework of the RoHS directive, manufacturers now work with coatings that are more environmentally friendly.  Trivalent or tetravalent chromium, hydrosilicon, phosphorous, zirconium, titanium or vanadium is now used, depending on the material properties required from the coated metal.

All of these coatings reliably protect steel and aluminum from oxidation and function as bonding agents – provided that the coating is uniformly applied and is neither too thick nor too thin.  To optimize quality while minimizing costs, the coating must be controlled regularly during the production process. To achieve best results, SPECTRO offers the SPECTRO PHOENIX II; a stable all-round instrument that can be consistently and easily operated even in the harsh production environments found within the metal industry 
The new application report documents six test series with the PHOENIX II: chromium, titanium and zirconium coatings on aluminum, chromium and phosphorous coatings on steel and hydrosilicon coating on chromated steel. The instrument delivered extremely reliable results in all of the tests. The deviations were clearly below one percent of the application weight.

In a typical application, an employee cuts several seven by ten centimeter samples from the steel or aluminum. The samples are then placed in succession with the coated layer down into the SPECTRO PHOENIX II sample chamber. The employee starts the measurement on the intuitive touch screen and receives the exact measurement results within several minutes.

SPECTRO PHOENIX II reaches its limits for applications in which the spectral lines for the coating and the carrier are very close together.  An example of this is thin chromating on steel sheets. For these types of applications, SPECTRO offers the SPECTRO XEPOS high-end XRF instrument that utilizes a higher spectral resolution than the PHOENIX II and also can reliably distinguish between spectral lines that lie close together. 
The XEPOS offers additional advantages in laboratories with high sample volumes: Several samples can be placed simultaneously onto the sample changer in the XEPOS. These can then be automatically processed. The examination of coatings with the SPECTRO XEPOS also is documented in application reports that are available free-of-charge at 

SPECTRO is one of the worldwide leading suppliers of analytical instruments for optical emission and x-ray fluorescence spectrometry. As a member of the AMETEK Materials Analysis Division, SPECTRO manufactures advanced instruments, develops the best solutions for strongly varying applications and provides exemplary customer service. Innovation, instrument concerns and customer relations are its main activities. From its foundation in 1979 until today, more than 26,000 analytical instruments have been delivered to customers around the world.

AMETEK, Inc. is a leading global manufacturer of electronic instruments and electric motors with an annual turnover of approximately 1.8 billion US$. AMETEK’s corporate growth plan is based on four key strategies: Operative excellence, strategic acquisitions and alliances, geographic and market expansion as well as new products. AMETEK’s common stock is a component of the S&P MidCap 400 Index and the Russell 1000 Index.

Please contact Tom Milner for additional information, Tel: +49.2821.892-0, 
Fax: +49.2821.892-2200, E-Mail: