Hardness refers to various properties of matter Matter is a term that traditionally refers to the substance that all objects are made of. The common way to identify this "substance" is through its physical properties; a common definition of matter is anything that has mass and occupies a volume. However, this definition has to be revised in light of quantum mechanics, where the in the solid The solid state of matter is one of the three main states that matter is found in. The solid state is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a gas does phase In the physical sciences, a phase is a region of space , throughout which all physical properties of a material are essentially uniform. Examples of physical properties include density, index of refraction, and chemical composition. A simple description is that a phase is a region of material that is chemically uniform, physically distinct, and ( that give it high resistance to various kinds of shape change when force In physics, the concept of force is used to describe how a massive body is affected by acceleration or mechanical stress. Force can also be described by intuitive concepts such as a push or pull that can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform. Related concepts to is applied. Hard matter is contrasted with soft matter Soft matter or Soft condensed matter is a subfield of condensed matter comprising a variety of physical states that are easily deformed by thermal stresses or thermal fluctuations. They include liquids, colloids, polymers, foams, gels, granular materials, and a number of biological materials. These materials share an important common feature in.
Macroscopic hardness is generally characterized by strong intermolecular bonds In physics, chemistry, and biology, intermolecular forces are forces that act between stable molecules or between functional groups of macromolecules. Intermolecular forces include momentary attractions between molecules, diatomic free elements, and individual atoms. These forces, most notably London Dispersion forces, dipole-dipole interactions. However, the behavior of solid materials under force is complex, resulting in several different scientific definitions of what might be called "hardness" in everyday usage.
In materials science Materials science or materials engineering is an interdisciplinary field involving the properties of matter and its applications to various areas of science and engineering. This science investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It includes elements of applied, there are three principal operational definitions An operational definition is a demonstration of a process – such as a variable, term, or object – in terms of the specific process or set of validation tests used to determine its presence and quantity. The term was coined by Percy Williams Bridgman . Properties described in this manner must be sufficiently accessible, so that persons other of hardness:
- Scratch hardness: Resistance to fracture The word fracture is often applied to bones of living creatures, or to crystals or crystalline materials, such as gemstones or metal. Sometimes, in crystalline materials, individual crystals fracture without the body actually separating into two or more pieces. Depending on the substance which is fractured, a fracture reduces strength or inhibits or plastic (permanent) deformation Plastic deformation in solids is a term used in metallurgy, materials science and solid state physics, and refers to an irreversible change in the internal molecular structure of an object. This change may be due to either (or both) of the following factors: due to friction from a sharp object
- Indentation hardness: Resistance to plastic (permanent) deformation Plastic deformation in solids is a term used in metallurgy, materials science and solid state physics, and refers to an irreversible change in the internal molecular structure of an object. This change may be due to either (or both) of the following factors: due to a constant load from a sharp object
- Rebound hardness: Height of the bounce of an object dropped on the material, related to elasticity In physics, elasticity is the physical property of a material that returns to its original shape after the stress , that made it deform, is removed. The relative amount of deformation is called the strain.
In physics, hardness encompasses:
- Elasticity In physics, elasticity is the physical property of a material that returns to its original shape after the stress , that made it deform, is removed. The relative amount of deformation is called the strain, plasticity In physics and materials science, plasticity describes the deformation of a material undergoing non-reversible changes of shape in response to applied forces. For example, a solid piece of metal or plastic being bent or pounded into a new shape displays plasticity as permanent changes occur within the material itself. By contrast, a permanent, viscosity Viscosity is a measure of the resistance of a fluid which is being deformed by either shear stress or extensional stress. In everyday terms , viscosity is "thickness". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity. Viscosity describes a fluid's internal resistance, and viscoelasticity Viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Viscous materials, like honey, resist shear flow and strain linearly with time when a stress is applied. Elastic materials strain instantaneously when stretched and just as quickly return to their original state once the
- Strength In materials science, the strength of a material is its ability to withstand an applied stress without failure. Yield strength refers to the point on the engineering stress-strain curve beyond which the material begins deformation that cannot be reversed upon removal of the loading. Ultimate strength refers to the point on the engineering stress- and strain In continuum mechanics, deformation is the change in shape and/or size of a continuum body after it undergoes a displacement between an initial or undeformed configuration , at time , and a current or deformed configuration , at the current time .[clarification needed]
- Brittleness A material is brittle if it is liable to fracture when subjected to stress. That is, it has little tendency to deform before fracture. This fracture absorbs relatively little energy, even in materials of high strength, and usually makes a snapping sound/ductility Ductility is a mechanical property used to describe the extent to which materials can be deformed plastically without fracture and toughness Toughness, in materials science and metallurgy, is the resistance to fracture of a material when stressed. It is defined as the amount of energy per volume that a material can absorb before rupturing
The equation based definition of hardness is the pressure applied over the projected contact area between the indenter and the material being tested. As a result hardness values are typically reported in units of pressure, although this is only a "true" pressure if the indenter and surface interface is perfectly flat.
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In addition to Young (now at Ruhr-University Bochum in Germany) and Dunand, James N. and Margie M. Krebs Professor of Materials Science at Northwestern's ...
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can even shorten the life of fabrics and clothes Does this mean that students who live in areas with hard water keep up with the latest fashions since their clothes wear out faster More information Hard water and water softening Stephen Lower
