Physics:Scratch hardness
Scratch hardness refers to the hardness of a material in terms of resistance to scratches and abrasion by a harder material forcefully drawn over its surface. Scratch hardness test or scratch test refers to any of a number of methods of measuring scratch hardness. Resistance to abrasion is less affected by surface variations than indentation methods. Scratch hardness is measured with a sclerometer.[1]
Attempting to scratch a surface to test a material is a very old technique.[2] The first scientific attempt to quantify materials by scratch tests was by mineralogist Friedrich Mohs in 1812 (see Mohs scale).[3][4] The Mohs scale is based on relative scratch hardness of different materials; with talc assigned a value of 1 and diamond assigned a value of 10.[5] Mohs's scale had two limitations: it was not linear, and most modern abrasives fall between 9 and 10.Cite error: Closing </ref> missing for <ref> tag Charles E. Wooddell, working at the Carborundum Company, extended the scale further by using resistance to abrasion, and extrapolating the scale based on 7 for quartz and 9 for corundum, resulting in a value of 42.4 for South American brown diamond bort.[6][7]
There is a linear relationship between cohesive energy density (lattice energy per volume) and Wooddell wear resistance, occurring between corundum (H=9) and diamond (H=42.5).[8]
See also
- Scratch test (disambiguation)
References
- ↑ George F. Vander Voort (1999). Metallography, Principles and Practice. ASM International. pp. 368–369. ISBN 9781615032365. https://books.google.com/books?id=GRQC8zYqtBIC&pg=PA369.
- ↑ Akono, A-T.; P. Reis; F-J. Ulm. (2011). "Scratching as a Fracture Process: From Butter to Steel". Physical Review Letters (American Physical Society) 106 (20): 2. doi:10.1103/PhysRevLett.106.204302. PMID 21668232. Bibcode: 2011PhRvL.106t4302A. https://dspace.mit.edu/bitstream/handle/1721.1/65375/Akono-2011-Scratching%20as%20a%20Frac.pdf?sequence=2&isAllowed=y. Retrieved 2022-05-03. "We present results of a hybrid experimental and theoretical investigation of the fracture scaling in scratch tests and show that scratching is a fracture dominated process. Validated for paraffin wax, cement paste, Jurassic limestone and steel, we derive a model that provides a quantitative means to relate quantities measured in scratch tests to fracture properties of materials at multiple scales. The scalability of scratching for different probes and depths opens new venues towards miniaturization of our technique, to extract fracture properties of materials at even smaller length scales.".
- ↑ von Groth, Paul Heinrich (1926) (in de). Entwicklungsgeschichte der Mineralogischen Wissenschaften. Berlin: Springer. p. 250. ISBN 9783662409107. https://books.google.com/books?id=tD0LAQAAIAAJ&q=+Härteskala+1812. "In demselben Jahre (1812) wurde MOHS als Professor am Joanneum angestellt und veröffentliche den ersten Teil seines Werkes "Versuch einer Elementarmethode zur naturhistorischen Bestimmung und Erkennung der Fossilien", in welcher die bekannte Härteskala aufgestellt wurde."
- ↑ "Mohs hardness" in Encyclopædia Britannica Online
- ↑ David Tabor (1951). The Hardness of Metals. OUP Oxford. ISBN 978-0-19-850776-5. https://books.google.com/books?id=b-9LdJ5FHXYC. Retrieved 2022-05-03.
- ↑ Wooddell, Charles E. (1935). "Method of Comparing the Hardness of Electric Furnace Products and Natural Abrasives". Transactions of the Electrochemical Society 68: 111–130. doi:10.1149/1.3493860. https://ur.booksc.eu/book/41260599/4bfed3. Retrieved 2022-04-22.
- ↑ Henry Chandler (1963). "Industrial Diamond : A Materials Survey". Information Circular (United States Department of the Interior) (8200): 6–7. https://books.google.com/books?id=zG_RtgVIsKMC&pg=RA9-PA6. Retrieved 2022-05-03.
- ↑ Plendl, Johannes N.; Gielisse, Peter J. (1 Feb 1962). "Hardness of Nonmetallic Solids on an Atomic Basis". Physical Review 125 (3): 828–832. doi:10.1103/PhysRev.125.828. Bibcode: 1962PhRv..125..828P. https://journals.aps.org/pr/abstract/10.1103/PhysRev.125.828. Retrieved 2022-04-22.
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