Acid resistance means the property of a solid (for example a metal) not to be soluble in acid or be capable of dissolving an acidic component even at high temperatures. Substances such as PEEK, glass or polytetrafluoroethylene as well as all precious metals and some passivation metals are resistant (indeed insert) to many acids.
A metal or a substance, which does not dissolve in any or almost no base or is attacked by it, is designated as alkali-resistant. Many metals, in particular gold and platinum, but also corrosion-resistant metals such as tungsten, are alkali-resistant since a protective layer forms on the surface in contact with alkaline solutions, as a result of which they are passivated. They can no longer corrode further and therefore do not dissolve.
An amorphous material (Greek: amorph: without shape) is a substance (according to the disciplines of Physics and Chemistry) in which atoms do not form an ordered structure, but an irregular pattern, and have only a short-range order. Unlike amorphous materials, regularly structured materials are called crystals.
Biocompatible refers to medical devices or materials that do not have a negative influence on the metabolism of living tissues when in direct contact. In implantology, biocompatibility plays a particularly important role. Since implants are in direct contact with the surrounding tissues for a long period of time, they are not allowed to cause any defensive reactions.
Corrosion is from a technical point of view the reaction of a material with its environment, which causes a measurable change in the material and can lead to a deterioration in the function of a component or system. Corrosion caused by living organisms is called biocorrosion.
In the case of materials, creep resistance refers to the time and temperature dependent plastic deformation under constant load.
A volume in which an electric field is found without significant electrical conductivity is called dielectric. A dielectric can be a gas, a liquid or a solid.
Ductility (derived from the Latin: ducere) is the property of a material to deform strongly when overloaded before it fails. For example, glass breaks without noticeable deformations; Steel, on the other hand, can deform plastically by up to 25% before it tears. Gold is so ductile that it can be stretched to a thickness.
Materials with this property are important in the construction industry, as a load-bearing structure "announces" its failure in a clearly visible way before it collapses. Ductile materials are also required in the automotive industry, since a car has to deform plastically in the event of an accident and not break apart. Earlier, ductility was a synonym for forgeability.
Fatigue resistance is the ability to withstand many load transitions before embrittlement and cracking occur.
The material fatigue describes a slow progressing damage process in a material under environmental influences such as changing mechanical load, changing temperature, UV radiation, etc.
Homopolymer / Copolymer
Homopolymers are polymers in which the macromolecules consist of basic building blocks of the same type.
Copolymers or heteropolymers are polymers composed of two or more different monomer units. They thus form the contrast to homopolymers.
From the Greek (hydro = water and phob = repellent) water-repellent. Property of a substance to have no affinity for water, not to be dissolved in it, nor to be wetted by water.
The notched impact strength is a measure of the resistance of a material to a striking (dynamic) stress. The unit is the notched impact work in relation to the fracture area in [J/cm²].
The toughness is dependent on the temperature (warm steel is tougher than cold steel) and the sample shape (notched steel is less tough).
The notch impact strength is determined in the notched impact test. The dynamic bending in a short time causes a fracture, often without the flow of the material observed during slow loading.
Semiconductors are substances which have both properties of insulators as well as of conductors. Which of these properties are predominant is determined by the external conditions and disturbances in the structure of the atomic lattice of a semiconductor. One of the most important semiconductor materials is silicon. Their electrical conductivity lies between that of non-conductors and conductors.
Viscosity is a measure of the resistance to flow exhibited by fluids. The reciprocal of viscosity is fluidity, a measure of the fluidity of a fluid. The larger the viscosity, the more viscous (less flowable) is the fluid; the lower the viscosity, the more fluid (flowable) it is.
When material undergo a quantitative loss in volume, no matter how minimal, wear is said to occur. All incidences of wear result from physical interaction between two or more "bodies" in relative motion to one another. Often the softer material in the loaded system suffers a higher reduction in quantitative volume.