Looking for a color change with pressure?
OliKrom has acquired a unique expertise in materials (from the chemistry to the production of pigment, ink, paint,...) capable of changing colors under pressure, impact or deformation.
This is a very little explored scientific field, yet the field of applications in the industrial and predictive maintenance fields are numerous.
Piezochromism (from the Greek piezô "to squeeze, to press" and chromos "the color") is by definition constituted of a material (pigment, dye, ink, paint, composite...) whose optical transition depends on macroscopic mechanical stimuli (pressure). From experience, we know that there is still a large gap between market expectations and the technological maturity acquired by piezochromic chemistry.
Are you looking for a piezochromic property adapted to your specifications?
According to your specifications, we select the most suitable solution. We have developed examples from the chemistry of organic compounds, organometallic complexes, polymers and composites. Each of these families has advantages and disadvantages.
Everything happens at the molecular level. The physical phenomenon responsible for the piezochromic property is a structural transition. The mechanisms involved are mainly molecular reorganization within a solid, modification of structures containing an open/closed form, cyclization, E/Z double bond isomerization process.
According to your request, our teams will program the piezochromic material. By chemical modification, we will adjust the threshold value according to the pressure. We will modulate the colors changing in the ultraviolet, visible and/or infrared regions.
We distinguish two main classes of piezochrome materials, depending on whether the color change property is reversible or irreversible.
Modification of the colors following the application of a pressure, and return to the initial coloring when the stress returns to its initial level. Possibility to adjust the optical transition, the threshold value with the percentage of deformation, elongation.
Definitive transition above a defined pressure threshold (of a shock). Possibility to adapt the threshold (energy) of triggering, the coloring of the initial and final states.
By experience, we know the main pitfalls encountered with piezochromic materials: evaluation of the right threshold, loss of sensitivity to pressure during formulation and/or industrial process, low coloring power, process fatigue, toxicity of some components, etc. In some cases, the influence of the temperature on the mechanisms of piezochromy with the possibility of combining thermochromic effects.
This is why we have chosen to be with you from the idea to the final product, in order to intervene efficiently at each stage of your project: research and development, pre-industrialization and industrialization.
Aeronautic, space, Defense
In the aeronautical, space and Defense fields, the use of piezochromic coatings is studied to control the health of composite structures.
Over the last decades, the adoption of composite materials has been increasing (airplanes, helicopters, engines, missiles). This craze can be explained by the advantages of these materials over metallic materials: their high stiffness and specificity, which allow for lighter and more efficient structures, great flexibility in design, and fatigue resistance.
One of the fundamental issues is the health control of structures and the early detection of damage. This is generally done either by visual inspection or by various non-destructive testing (NDT) methods such as ultrasonic, eddy current, etc.
The use of piezochromic coatings on the surface of a composite allows to associate a color change to the damage (threshold value). According to the request, the transition can affect the absorption and/or emission of a luminescence signal.
Piezo-chromic coatings in aeronautics represent a first level of surveillance allowing a controller to quickly detect an anomaly.
In the field of industrial maintenance (energy, petrochemical, nuclear...), the use of piezochromic materials is also of great interest for the visual detection of potential shocks or deformations of some industrial parts.
Among the potential sectors, we can mention the oil industry (pipelines, tubes, bars, welds, tanks), the naval industry (control of hulls), the automotive industry (control of engine blocks), the steel industry, the boiler making and the piping in manufacturing.
But also the energy industry: nuclear reactors, boilers, piping, turbines, etc. (maintenance of installations), the railway industry in manufacturing and maintenance, particularly for safety components (axles, wheels, bogies), civil engineering and construction...
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