hardness

Also known as hard

AI overview

Hardness is a measure of how well a material resists being dented, scratched, or permanently shaped when force is applied to it. Different materials have different levels of hardness—for example, metals like titanium are much harder than softer metals like sodium, wood, or plastic—and a material's hardness generally depends on the strength of the bonds between its molecules.

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Research

41,221 papers

Muscle hardness and masticatory myofascial pain: Assessment and clinical relevance.ReviewJournal of oral rehabilitation · 2018Costa YM, Ariji Y, Ferreira DMAO et al.DOI: 10.1111/joor.12644
An Exploration Into the Measurement and Reporting of Food Firmness and Hardness.ReviewJournal of texture studies · 2024Rosenthal AJDOI: 10.1111/jtxs.12873
Hardness methods for testing maize kernels.ReviewJournal of agricultural and food chemistry · 2009Fox G, Manley MDOI: 10.1021/jf900623w
Hardness Development in Resin Composite Core Materials.Journal of prosthodontics : official journal of the American College of Prosthodontists · 2022Lien W, Roberts H, Vandewalle KDOI: 10.1111/jopr.13399
Atoms-In-Molecules' Faces of Chemical Hardness by Conceptual Density Functional Theory.ReviewMolecules (Basel, Switzerland) · 2022Kaya S, Putz MVDOI: 10.3390/molecules27248825
Reliability of colour and hardness clinical examinations in detecting dentine caries severity: a systematic review and meta-analysis.Scientific reports · 2019Hon L, Mohamed A, Lynch EDOI: 10.1038/s41598-019-41270-6
Hardness Perceived When Sliding Over Roughened Surfaces.IEEE transactions on haptics · 2024Sun Q, Okamoto S, Wang HDOI: 10.1109/TOH.2024.3405728
Water hardness and digestive diseases: a large-scale population-based prospective cohort study.International journal of surgery (London, England) · 2026He Q, Sun M, Huang J et al.DOI: 10.1097/JS9.0000000000003506

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Wikidata facts

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Commons category: Hardness

Sources (5)

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~14 min read

Article

12 sections

Contents

Measures
Scratch hardness{{Anchor|Scratch hardness}}
Indentation hardness
Rebound hardness {{anchor|Rebound}}
Hardening
In solid mechanics
Mechanisms and theory
Relation between hardness number and stress-strain curve
See also
References
Further reading
External links

In materials science, hardness (antonym: softness) is a measure of the resistance to plastic deformation, such as an indentation (over an area) or a scratch (linear), induced mechanically either by pressing or abrasion. In general, different materials differ in their hardness; for example hard metals such as titanium and beryllium are harder than soft metals such as sodium and metallic tin, or wood and common plastics. Macroscopic hardness is generally characterized by strong intermolecular bonds, but the behavior of solid materials under force is complex; therefore, hardness can be measured in different ways, such as scratch hardness, indentation hardness, and rebound hardness. Hardness is dependent on ductility, elastic stiffness, plasticity, strain, strength, toughness, viscoelasticity, and viscosity. Common examples of hard matter are ceramics, concrete, certain metals, and superhard materials, which can be contrasted with soft matter.

==Measures== thumb|A Vickers hardness tester