The Mallard Analysis Laboratory
Our Materials / Metallurgy laboratory is now operational and complements our expertise in the fields of Mechanics / Metallurgy by providing us with the capacity to analyze structures, treatments ... And in particular our coatings made by dry process.
Our analysis possibilities and the first applications:
The preparation of samples for microstructural analysis begins with a quality cut, carried out using a micro-cutting machine allowing to control the speed and the force of the wheel applied on the material, in order to minimize the depth of the deformations onto the sample surface.
Mallard is able to make precision cuts on all types of materials: polymer, metallic, ceramic or carbide, with low or very high hardness (> 1000 HV).
Before metallographic preparation, the samples are hot-mounted using heat and pressure to embed and preserve the edges of the complex shaped samples. For heat sensitive materials, cold mounting epoxy resin is an alternative.
Mallard is equipped with an automatic polishing machine to finalize the metallographic preparation by starting from an as-cut sample surface to a mirror-polish surface, allowing the observation of the microstructural specificities of the sample.
Each sample is made of a different nature, Mallard develops its polishing recipes based on the experience of its qualified and experienced operators, as well as on quality products adapted to the nature and characteristics of the materials to be analyzed. The success of the preparation depends on the successive reduction in the size of the abrasive particles, the role of which is to cut the material more and more finely, using diamond suspensions up to 1 μm and then finishing with nanometric colloidal particles.
Preparation bench with micro-cutting, mouting and polishing machines (from right to left).
This is at the heart of the metallographic characterization, the microstructural observation is carried out using an optical microscope offering a resolution of the order of a micron (thousandth of a millimeter). In the case of thermal spray coating, the processing and processing of the images obtained on the polished samples allows access to characteristics, such as the porosity rate of the layers, the rate of unmelted particles, the contamination of the interface and the quality of the connection with the substrate. For composite mixtures, the quantification of each of the constituents is also possible, thanks to the processing of micrographic images by image analysis software.
In the case of bulk materials, we have the possibility of carrying out selective chemical attacks in order to reveal the microstructural particularities of the samples, such as the presence of specific phases (carbides, nitrides, etc.), twins, grain boundaries, precipitates.
A key characteristic in the case of coatings, Mallard is equipped with a micro-hardness tester which allows the hardness of the sample to be measured precisely and locally. Our equipment has two types of indenter: Vickers and Knoop (in accordance with international standards ISO 65607, ISO 4545 and ASTM E384), with a wide load range from 10gf (HK / HV0.01) to 2kgf (HK / HV2). The samples are handled using an XY table equipped with analog micrometers making it possible to produce hardness filiations through the sample thickness with an accuracy of up to 10 µm.
Metallographic analysis bench with micro-hardness tester and optical microscope (from left to right)
Example of observations:
Copper cold spray coating on Aluminum substrate
Thin deposit of approximately 100µm of 99.95% copper, porosity <0.1%
Microhardness measurement on duplex super alloy
Hardness filiation: 4 points in the deposit and 2 points in the substrate
Build-up stainless steel coating by cold spray
Thick deposit of stainless steel using a portable high pressure cold spray
HVOF WC-17Co coating
Ultra hard tungsten carbide deposit, micro-hardness > 1100 HV and porosity <1%.