The mechanical characteristics of two-dimensional (2D) materials are of tremendous interest. Alfa Chemistry provides specialized bulge testing services for 2D materials to assist clients in better understanding and quantifying such features. When compared to nanoindentation approaches, this testing method eliminates the influences of the substrate as well as the clamping concerns that tensile testing requires. Bulge testing has been used to study the mechanical characteristics of freestanding films manufactured from a range of 2D materials extensively. Please get in touch with us as soon as possible so that we can help you with your 2D material testing!
Bulge Testing Methods
Alfa Chemistry determines the mechanical characteristics of 2D material films using the bulge test, which involves a connection between the applied uniform pressure and the film's out-of-plane deflection. The membrane is transferred or clamped to cover the pores on the solid support in this procedure. By providing a modest amount of overpressure to the hole, the membrane is distorted. Optical microscopes with calibrated vertical displacements, laser interferometers, Raman spectroscopy, and AFM can detect deflection across a wide range from tens of nanometers to micrometers. Stress may be determined by measuring the curvature of the intumescent membrane, which is comparable to out-of-plane deflection.
Method One: Internal decompression to create concave deflection within the membrane
Example: Graphene expansion test by decompression in pores
Fig 1. Crack extension histories of the mother/branched crack with typical images showing fracture evolution. (Hwangbo Y, et al. 2014)
Alfa Chemistry observes and analyzes the fracture properties of monolayer CVD-grown graphene using a pressured expansion test equipment. At normal temperature, monolayer CVD graphene seems to generate subcritical cracks. The fracture propagates in a discontinuous and complicated manner once the smallest observable crack develops. The failure of CVD-grown graphene was caught by a high-speed camera in less than 2 milliseconds. The growth process is characterized by a continuous fracture stop and restarts pattern, similar to that seen in 3D bulk materials. The fracture toughness of CVD-grown graphene was measured to be 10.7 ± 3.3 MPa m1/2. The benefit of compressive expansion testing is that it uses a high-speed camera to depict fracture growth situations.
Method Two: External depressurization to create convex deflection inside the membrane
Example: Expansion test of graphene by decompression outside the pore.
Alfa Chemistry used Raman spectroscopy to show the mechanical behavior of 2D crystals in an indirect way. In systems that may be utilized to examine the intrinsic characteristics of 2D crystals, Raman spectroscopy is widely employed to observe vibrational, rotational, and other low-frequency modes.
Graphene's Raman spectra are subject to mechanical deformation. When graphene is subjected to uniaxial strain, red-shift and splitting of the Raman G and 2D bands are observed experimentally. The Young's modulus of graphene layers may be determined by utilizing Raman spectroscopy to measure the strain caused on a compressed graphene balloon and comparing the strain to numerical calculations using finite element techniques.
Fig 2. 3D rendering of an AFM image showing the deformed shape of a monolayer graphene membrane with bulge/blister testing. (Koenig S. P, et al. 2011)
Why Choose Us
- We have extensive experience in 2D mechanics of materials research and have been working on different mechanical properties testing techniques.
- Our methods are diverse, and professional, and do not damage the samples.
- We create solutions that are unique to our customers' specific requirements.
You didn't find what you were looking for? We can deliver unique solutions because of our wide skill set. Please get in touch with us to discuss your needs.
References
- Hwangbo Y, et al. (2014). "Fracture characteristics of monolayer CVD-graphene." Sci Rep. 4: 04439.
- Koenig S. P, et al. (2011). "Ultrastrong Adhesion of Graphene Membranes." Nat. Nanotechnol. 6: 543-546.
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