The problem?
The ski goggle manufacturer wants to develop a new generation of high-end goggles (#R&D) incorporating innovative features to improve the user experience. In particular, these goggles must be equipped with a transparent conductive coating that allows:
- fog management
- increased resistance to scratches and wear to meet the demands of outdoor sports activities
- A lightweight and flexible design adapted to ergonomic constraints, while maintaining excellent optical quality.
However, the choice of base materials, particularly between rigid substrates (such as mineral glass) and flexible substrates (such as PET), strongly influences the quality of the metal oxide coating used for these features.
Objectives : Compare the quality of a metal oxide coating on two types of substrates: mineral glass and PET (polyethylene terephthalate) glass. This comparison is performed using topographic and electrical analysis to characterize the homogeneity and conductive properties of the coating.
Methodological approach
- Sample preparation
Metal oxide deposits are applied to two substrates:
Mineral glass: this type of glass is chosen for its rigid and stable surface, providing an ideal base for the uniform application of a thin coating.
A PET glass: PET, a flexible polymer material, is widely used in applications where lightness and strength are required, but it presents constraints for the uniformity of thin deposits.
Three distinct areas are studied for each substrate to ensure that the results are representative. These areas are chosen at random, avoiding the edges, to minimize bias due to non-homogeneous conditions.
- Atomic force microscope (AFM) analysis
Non-contact mode: this mode provides accurate 3D mapping of the sample surface. These images are used to assess the homogeneity of the metal oxide deposit on each substrate. Topographical parameters such as average roughness and local variations are analyzed.
Electrical mode: this mode allows the electrical conductivity properties of metal oxide coatings to be measured. Since metal oxide is a conductive material, differences in electrical response between samples can reflect variations in deposit quality.
Results
1. Topographic analysis
The 3D maps obtained in non-contact mode revealed the following differences:
Mineral glass: the metal oxide deposit is very homogeneous, with the continuous presence of grains measuring around 100 nanometers in diameter. Average roughness measurements give similar results. This indicates that the coating is of good quality on this substrate.
PET glass: defects are observed on the surface of the coating, indicating reduced homogeneity. The defective areas include irregularities in the thickness of the deposit, which can be attributed to stresses related to the flexibility of the substrate.
2. Electrical analysis
Electrical measurements show significantly higher conductivity for the deposit on mineral glass compared to PET glass. This difference is attributed to:
- The structural continuity of the deposit on mineral glass
- Irregularities present on PET glass, which can cause local breaks in the metal oxide conductor network.
3. Summary of observations
Topographic and electrical analysis agree and indicate that:
- The metal oxide deposit is more uniform and has better conductive properties on mineral glass.
- The coating on the PET glass has structural defects and resembles holes, which negatively impact its overall quality. These holes could be reduced by adjusting the deposition parameters or pre-treating the PET substrate.
Conclusion
This study highlights the significant differences in quality between metal oxide coatings applied to two types of substrates, mineral glass and PET glass, in the context of developing high-end ski goggles.
Topographic and electrical analysis performed using atomic force microscopy (AFM) show that:
- Mineral glass provides a rigid and stable surface that promotes uniform and smooth deposition. This structural uniformity results in high electrical conductivity, which is essential for ensuring coating performance, particularly in anti-fog heating applications.
- Although PET glass is lightweight and flexible, it has irregularities in the metal oxide coating. These defects, which resemble holes, affect both homogeneity and electrical conductivity, making this substrate less effective in its current state.
Implications for the development of ski goggles
The results show that mineral glass is the optimal choice for ensuring high-quality coating, but its weight and rigidity may limit its use in ski goggles. On the other hand, improvements to PET glass, such as surface treatments or optimizations of deposition parameters, could make it a viable candidate.
In conclusion, this study guides manufacturers in their strategic choices and highlights the need for a compromise between technical performance and the ergonomic constraints specific to high-performance sports equipment.
If you have any questions about this case study, please contact us directly at contact@filab.fr.
Other case studies you may be interested in
Optimization of the coating of a can
One of our clients wants expertise and optimization of the coating used on the cans it uses to market its beverages. Learn more +Services related to the case study
Laboratory specializing in analysis and expertise for industrial companies
Contact us
Our services are reserved for professionals.
Frequently asked questions
Why compare a metal oxide coating on mineral glass and PET?
The nature of the substrate can influence the uniformity and properties of the coating intended for the ski mask. FILAB compared rigid mineral glass with flexible PET to assess the quality of the transparent conductive coating. The aim was to shed light on the trade-off between the coating’s characteristics and the product’s requirements for lightness and flexibility.
What is the contribution of AFM in assessing the homogeneity of a thin coating?
Atomic force microscopy provides a map of the surface topography and enables comparison of roughness or local irregularities. In the FILAB study, these observations were carried out on several areas of both substrates. They revealed a more continuous deposition on mineral glass and more defects on PET.
Why combine topographical observations with electrical measurements of the deposit?
Topography describes the continuity and irregularities of the coating, while electrical measurements provide additional information about its functional behavior. In this study, the two approaches were consistent: the deposit on mineral glass was more homogeneous and showed a better conductive response than the deposit on the PET substrate used for comparison.
What did the examination of the coating deposited on the PET reveal?
The examination revealed local defects and lower deposit uniformity, with irregularities described as hole-like areas. These observations were linked to a less favorable electrical response. The conclusions concern the deposit and the PET studied, under their respective preparation and characterization conditions.
What approaches have been proposed to improve deposition on a flexible substrate?
The article considers pretreating the PET and optimizing the deposition parameters to reduce the irregularities observed. These approaches would support further development while preserving the substrate’s advantages in terms of lightness and flexibility. They are presented as potential avenues for improvement to be explored, rather than as performance levels already achieved.