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Plastics Properties and Testing
Published in Manas Chanda, Plastics Technology Handbook, 2017
Basically, scratch hardness is a measure of the resistance the test sample has to being scratched by other materials. The most common way of qualifying this property is by means of the Mohs scale. On this scale various materials are classified from 1 to 10. The materials used, as shown in Figure 3.43, range from talc (1) to diamond (10). Each material on the scale can scratch the materials that have a lower Mohs number; however, the Mohs scale is not of much value for classifying plastic materials, because most common plastics fall in the 2–3 Mohs range. However, the basic technique of scratch hardness may be used to establish the relative merits of different plastic materials from their ability to scratch one another.
Thermal and Mechanical Performance of Nanocomposite Insulating Materials
Published in Toshikatsu Tanaka, Takahiro Imai, Advanced Nanodielectrics, 2017
Satoru Hishikawa, Shigenori Okada, Takahiro Imai, Toshio Shimizu
There has been a report on scratch hardness in polyamide nanocomposite films with the dispersion of a 40 nm nanofiller [9]. Scratch hardness is measured by making a scratch of certain width and measuring the load required to make the scratch. As shown in Fig. 6.18a, nanocomposite films exhibited more improvement in scratch hardness with increasing filler content compared with polyamide films containing a dispersion of microfiller with a particle diameter of 3 μm.
Material Hardness and the Size Effect
Published in Yichun Zhou, Li Yang, Yongli Huang, Micro- and MacroMechanical Properties of Materials, 2013
Yichun Zhou, Li Yang, Yongli Huang
Scratch hardness can reflect other mechanical properties such as fracture toughness and reduction of area. From the discussion in scratch testing theory, there is a strong relationship between scratch hardness and true fracture toughness SK. This relationship for lead, copper, and iron can be described by the following formula [10]: () SK=4.021b50-22.5,
Experimentally investigating hybrid polyurethane silica nanocomposites for DTM coating applications
Published in Surface Engineering, 2022
Sukanya Gangopadhyay, P. A. Mahanwar
Mechanical properties of the formulated coatings are noted in Table 3. All the coated panels had a DFT of 70 ± 5 microns. As seen from the table, with increasing nano-silica content from 0 to 10%, the scratch hardness improves from 400 g at 0% loading to 620 g at 10% loading with the highest value of 720 g at 8% loading as nano-silica reinforces the matrix by reducing voids. The pencil hardness is also observed to increase from 3H to 4H with nano-silica loading from 0 to 10% owing to reduced chain mobility along with flexibility due to the presence of aliphatic polyester groups in the polymer backbone resulting in better impact resistance. But with nano-silica loading beyond 8% surface roughness has been observed thereby deteriorating the adhesion of coated films with the metal substrate. It also makes the coating brittle due to increased porosity; therefore, sharp pencils and high loads cannot be sustained by such films.
Preparation and characterisation of acrylic resin for electro-deposited mono-coat coatings
Published in Indian Chemical Engineer, 2021
Shiv Charan Prajapati, Pramod Kumar Kamani
This property deals with the resistance of a material to indentation of scratching. The hardness of a coating material is generally tested by scratch hardness test which is done by scratch hardness tester (ASTM D 5178, Sheen Instruments Limited England). The panels were loaded with different weights until a clear scratch, showing the bare metal surface, was seen.