Cetim Grand Est

Cetim-Cermat is able to respond to your questions relating to corrosion tests, whether in terms of a standardised service provision, in terms of choice of material(s) or coating(s), or in terms of technical support to define and implement specific tests.

Standardised corrosion tests:

These tests are perfectly defined through standards (ISO, AFNOR, ASTM and NACE) or specifications. The following can be mentioned:

Atmospheric corrosion tests:

• Salt spray, Cass test,
• Kesternich test (SO2 atmosphere),
• Cyclical test (BS – T° - %HR): 3C, ECC1, etc.
• Immersion tests with measurement of weight losses, etc.

Tests of resistance to a given form of corrosion:

• Corrosion under stress (MgCl2, NaCl, etc.)
• Intergranular corrosion (Huey, Monypenny Strauss, etc.)
• Corrosion by pitting,
• Selective corrosion (dezincification, etc.)
• Exfoliation corrosion, etc.

Electrochemical tests performed in a given environment:

These tests allow access to certain parameters characteristic of the various forms of corrosion:

• Polarisation curves and plot of TAFEL straight lines (generalised corrosion),
• Polarisation resistance measurements (corrosion speed),
• Corrosion potential, pitting and repassivation potential (corrosion by pitting),
• Galvanic coupling,
• The Electrochemical impedance is used to describe the behavior of coating (passivation layer, varnish, paint, metal coating ...), principally from the determination of resistance existing during the transfer of forces.

These measures can be used to monitor a complex test

Examples:

• Determining which grade of stainless steel can withstand a waterborne paint
• Checking the corrosion resistance of a new coating by electrical impedance

Analysis of special corrosion, custom testing

These tests are defined after considering the risk of corrosion (which form(s) of corrosion and in which area (s)?) related to conditions of use.
In this case, all conditions can be envisaged, whether it is the duration or the assembly.
We possess an autoclave made of Hastelloy C276, ready to test different materials in aggressive environments (see below the features of the device).

Help in defining the suitable tests

Whether it relies in the choice of materials or simply verifying the quality of your suppliers’ parts, we are here to help you determine which test, especially in terms of duration, is best suitable for you.

Examples:

• Confined boiling test specially designed for a mixture of strong acids.
• Resistance to corrosion test in deionised water of a thin cobalt based alloy tube

Specific materials used for the analysis and expertise of corrosion:

• 3 tanks of salt spray
• a SO2 chamber
• 4 potentiostats (including a portable one)
• 2 frequency response analyzers (including a portable one)
• 1Hastelloy C276 autoclave / lining EFF: 13 liters, 250 ° C, 200bars

Chemical analysis of metals is a significant stage in physical-chemical characterisation processes and failure analysis.

Cetim-Cermat has complete equipment to characterise any metallic material in whatever size or shape:

Complete analysis of alloys

• Non-alloyed and lightly alloyed steels
• Stainless steels
• Cuprous metals (pure and alloyed coppers, brasses, bronzes, cuprous-aluminium)
• Alloyed and non-alloyed cast irons
• Aluminium alloys
• Zinc alloys
• Etc.

Specific analyses

• Oxygen (O2), nitrogen (N2)
• Hydrogen (H2)
• Carbon (C) and sulphur (S)
• Proportioning of metals in plastics
• Silicon by gravimetry in cast irons (COFRAC accredited analyses, range on request), aluminium, etc.
• Coatings, metallic or non-metallic

COFRAC accredited analyses (range communicated on request)

• Alloyed and non-alloyed steels
• Alloyed and non-alloyed cast irons
• Carbon, sulphur and silicon contents

Analysis on site

• Portable spark optical emission spectrometer
• 4 precalibrated programmes: steels (alloyed and non-alloyed), titanium bases, nickel bases and aluminium alloys
• Sorting, PMI (Positive Material Identification)
• Allows carbon content to be determined
• Also usable in the laboratory for a non-destructive analysis

Analyses in accordance with RoSH, REACH, etc. directives

Analyses of heavy metals, still called environmental analyses, are increasingly of current concern: the directive RoSH has been applicable since 1 July 2006, while the European ELV (End of Live Vehicle) directive is to come into application on 1 July 2007. Other directives, as with the WEEE (Waste Electrical and Electronic Equipment) also impose the proportioning of heavy metals.

Proportioning heavy metals

• By X-Ray Fluorescence spectrometry
• By plasma
• All types of parts

Proportioning of chromium VI (hexavalent chromium)

• In accordance with applicable standards
  (NF EN ISO 3613, ASTM D6492, etc.)
• Qualitative and quantitative
• On coatings with chromate finishing

Elementary micro-analysis

Two X-Ray Fluorescence probes coupled with a scanning electron microscope: an Energy Dispersive X-Ray (EDX) probe and a Wavelength Dispersive X-Ray (WDX) probe.

Examples of WDX probe use:
Detection of small quantities of sulphur on all small parts made of brass with lead (in EDX, interferences from lead and sulphur preventing sulphur detection).
Profile of carbon concentration on micrographic cross-section.

Surface analyses

• Elementary profiles using a Luminescent Discharge spectrometer
• Micro-analyses (see above and section on surface part failure analyses)
• Multi-layer coatings, whether metallic or not

Equipment:

• 4 JOBIN-YVON optical emission spectrometers: spark (SEO), plasma (ICP), luminescent discharge spectrometry (SDL or GDL)
• 1 PHILIPS PW 2404 wavelength dispersive X-Ray fluorescence spectrometer
• 2 OXFORD X-Ray fluorescence probes coupled to LEO scanning electron microscope
• 2 LECO gas analysers (oxygen + nitrogen, hydrogen)
• 1 LECO carbon and sulphur analyser
• 1 electrolyser (copper proportioning)
• 1 portable SEO BELEC COMPACT PORT analyser

All failures on production facilities or manufactured products (breakage, corrosion, wear, etc.) often lead to a loss of time, operation, and possibly penalties for late delivery. Let us note that, in some cases, consequences arise in safety terms

A failure, just like a non-conformance in the Quality field, is a setback from which one can draw an advantage to ensure it does not get repeated. rupture11

Let us take the example of breakages:
Less than 10% of these have the quality of the material as their origin; now, in most cases you just make do with checking the chemical composition or hardness of the said material. Generally, a broken part is considered for discard; now, the part really represents the result of an involuntary "industrial test" on full scale.

Analysis of the failure will allow for a diagnostic of the true causes as well as for the necessary corrective actions to be set up. Failure analysis is now more than ever a profitable investment as it provides a vehicle for progress.

Failure analysis has constituted our core skill for almost 30 years.

Our highly experienced multidisciplinary team is at your service to analyse failures, draw up reliable diagnostics and thus quickly propose relevant solutions.

Failure, just like any non-compliance in the field of quality, is a mistake from which we should learn from and prevent it from recurring.

The analysis of failures will help make a diagnostic, in order to identify the causes of recurring failures, before implementing corrective actions.

Failure analysis, our strengths:

• An experienced team: over 500 cases treated per year
• Performing and effective technical means (electron microscopy, EDX and WDX probe analysis, chemical analysis and mechanical testing, electrochemistry ...)
• Our multi-skills: Metallurgy & Mechanical (machinery breakdown, failure in transmissions, gears, bearings ...) - Corrosion and surface treatments - Failures of plastics and composites - Wear and deterioration of surfaces
• Interventions for the industry and as well for insurance companies and legal experts for litigation or investigations