Our technical glossary on the topic of coating thickness measurement, material analysis and the characterization of surfaces.
The use of an Aperture (collimator) restricts the cross-section of the primary X-ray beam, creating a measurement spot with a pre-defined size, which allows precise adjustment of the size and shape of the X-ray beam to the specimen geometry. Depending on the measurement system, individual fixed apertures or exchangeable multi-apertures are employed.
For measurements on very small objects such as the bond areas on leadframes, the Aperture is substituted by a special X-ray optics with mirrors or poly-capillaries, which simultaneously provides for both a very small measurement spot and high excitation intensity.
Using the COM function in a FISCHER X-Ray instrument, unknown samples can be assigned automatically to a predefined material class. These classes may be different kinds of materials, e.g. different alloys, specific coating thicknesses, or concentration ranges of a coating structure. The WinFTM® software can then automatically select the appropriate application to use for the measurement.
For example, in gold analysis, WinFTM® firstly determines the type of alloy and then selects the appropriate measuring application required to determine the gold content with high accuracy.
The Coulometric method is an electrochemical analysis method according to DIN EN ISO 2177, in order to determine the thickness of metal coatings.
It is often used for checking the quality of electroplated coatings, and for monitoring the thickness of the remaining pure tin on printed circuit boards. The method is also suitable for multi-layer coatings like chrome on nickel on copper on plastics.
The X-ray detector measures the energy distribution of the X-ray fluorescence radiation emitted by the sample. Detector types that are optimal for their respective purposes are available for various applications.
To measure on geometrically irregular parts or in indentations, FISCHERSCOPE® X-RAY instruments are equipped with a special feature for distance-based measurement correction: the DCM Method.
This function also allows for testing of complex surface shapes and for measurements in indentations, whereby WinFTM® automatically factors the current measuring distance in when computing the measurement result for a specific area.
When measuring according to the ESP method (Enhanced Stiffness Procedure), loading and unloading are incremental. This allows the quick for depth- and force-dependent determination of characteristics such as the Elastic Modulus of Indentation (EIT), the Indentation Hardness (HIT) or the Vickers Hardness (HV) – all at the same location.
Measurement of the ferrite content: It is relevant to determine the ferrite content of austenitic and duplex steel and to determine the portion of deformation martensite in austenitic materials, according to DIN EN ISO 17655 and according to the Basler-Standard. If the ferrite content is too low, then the welded material is susceptible to hot-cracking. If the ferrite content is too high, the toughness, ductility as well as the corrosion resistance of the steel are reduced.
Factors, which may influence the accuracy, must be taken into account individually by the user, such as the geometry of the sample, the thickness of claddings or the exterior form of the permeable structure.
All FISCHER microhardness instruments employ the Instrumented Indentation Test method – often called nanoindentation – for determining the Martens Hardness (HM). In contrast to other hardness tests, this method not only determines the plastic behaviour of the material, but additional material parameters can also be read from the measurement plot, such as the Elastic Modulus of Indentation(EIT), the Indentation Hardness (HIT) and the Indentation Creep (CIT), as well as the plastic and elastic deformation energies.
The test method is based on the fact that all electrically insulating coating materials have a much higher disruptive strength than air. Pore detection occurs at the defective spots through a spark-over (short circuit) between the test electrode and the conducting base. A defective spot may be a thin air channel (pore, crack) or a coating that is too thin over the conducting base underneath.
Special filters optimise the energy distribution of the primary X-radiation for a given application, absorbing any undesired spectral components of the radiation. Depending on the instrument type, either individual fixed filters or removable multi-filters are employed.
The primary X-radiation required for X-ray fluorescence analysis is generated using an X-ray tube in which a heated cathode emits electrons which are accelerated to a very high speed by applying high voltage. The X-radiation is created when these electrons strike the anode material of the tube, typically tungsten or molybdenum. To ensure that the X-ray tubes work reliably for years to come, each individual piece must pass extensive incoming inspection tests.
The X-ray generator developed by FISCHER integrates the shielded, oil-cooled tube with the high voltage generation, which results in excellent stability and long service life.
The weather resistance of an anodized finish is a function of sealing quality. According to DIN EN ISO 2931 and ASTM B 457-67, the admittance (Y) of a capacitor in which the anodic oxide film forms the dielectric is a good yard-stick of sealing quality. The ANOTEST® YMP30-S measures the admittance according to standards, and due to its design is ideally suited for on-site testing.
The shutter of the FISCHER X-Ray instrument is directly located in the beam path and is opened only for the duration of the measurement. In its closed state, it prevents the primary radiation from entering the measuring chamber. Monitored by the safety system, it opens only when the housing is completely closed, eliminating the risk of radiation for the operator.
In the X-Ray fluorescence analysis, the radiation emitted by the sample is depicted in the signal spectrum, the lines of which identify the elements contained in the sample. From this spectrum, the FISCHER WinFTM®-Software computes the desired parameters, such as coating thickness or element concentrations.
The STEP Test is used to simultaneously measure the potential differences between and the coating thicknesses of multiplex nickel coatings, allowing for an assessment of their corrosion behavior.
This is a variation of the Coulometric method.
Helmut Fischer (Thailand) Co., Ltd.
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