compound
elements of the same kind bond with each other
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| Term | Definition |
|---|---|
| compound | elements of the same kind bond with each other |
| alloy | different elements form a molecule together via bonds |
| mixture | different substances and molecules that are not bound to each other on an atomic level |
| crystalline structure | atoms or molecules bound together in a solid often form a strong, orderly, 3-dimensional pattern |
| amorphous structure | molecules don not follow a nicely repeating 3D pattern, long intertwined chains of molecules |
| chemical properties | material properties that are related to the atomic structure and the chemical composition of the material |
| composition | list of the elements or chemical compounds that make up the material, with an indication of the levels in which these components occur |
| crystal structure | the way the atoms or molecules of the material are arranged in repeating parts |
| microstructure | structure that becomes visible on the surface of the material when magnified by a factor of at least 10 |
| corrosion resistance | ability of a material to resist chemical or electrochemical affection by substances in its environment |
| physical properties | properties are related to the physics of the piece, often related to the environment the material is in |
| melting point | temperature at which a solid material becomes liquid when heated and solidifies when cooled. Many materials do not have a precisely defined melting point, but rather a melting range. |
| specific mass | mass (or weight) of a substance per unit volume, also called density |
| specific weight | ratio of the mass of a given volume of substance to the mass of an equal volume of water. |
| refractive index | |
| thermal properties | ratio of the speed of light in that substance to the speed of light in a vacuum |
| coefficient of thermal conductivity | λ (in W/m.K) amount of heat passing through a homogeneous material per unit of time, per unit of surface area, per unit of temperature gradient in the direction perpendicular to the surface |
| linear coefficient of expansion | α in (m/m.K) change in length per degree of temperature change |
| softening temperature | temperature at which a polymer exhibits a given degree of bend or deformation under a given load |
| water absorption capacity | percentage increase in weight of a substance when immersed in water under controlled conditions for a specified period of time |
| specific heat capacity | amount of heat required to raise one kilogram of a substance one degree Celsius in temperature |
| breakdown voltage | minimum voltage that causes a portion of an insulating material to experience electrical breakdown and become electrically conductive |
| specific electrical resistance | electrical resistance per unit length and per unit area of the cross-section, or the electrical resistance per unit length and per unit mass |
| mechanical properties | important when forces are applied to the material, mechanical properties depend on both chemical and physical properties of a material |
| tensile strength | ratio of the maximum load in a tensile test to the original cross-section of the test piece. Measured in N/m² |
| yield strength | maximum stress at which a material can stretch without plastic deformation |
| compressive strength | greatest pressure that a material can withstand without breaking |
| elasticity modulus | ratio of stress to strain in the elastic region. This is also a measure of the stiffness of a material |
| bend strength | tension in the outer edge of a uniaxially supported beam that undergoes a predetermined bending under the influence of a load |
| shear strength | stress at which breakage (shear) occurs in the plane of the cross-section of the material |
| hardness | resistance of a material to plastic deformation |
| notched impact strength | amount of energy required to cause a given volume of a material to break |
| stress | ratio between the force and the loaded area |
| strain | elongation, amount by which a material will stretch under a certain stress |
| tensile test | compression test, mainly used to determine the relationship between the average tensile stress and strain in many structural materials |
| conventional stress-strain diagram | |
| elastic behavior (stress-strain diagram) | if test piece returns to its original shape or length when the load acting on it is removed |
| plastic behavior (stress-strain diagram) | |
| yielding (stress-strain diagram) | slight increase in stress above the elastic limit results in a deterioration of the material and causes permanent deformation |
| strain hardening (stress-strain diagram) | When flow has ceased, increasing the load causes the curve to rise continuously, but to flatten out until a tension is reached, which is called the ultimate strength or tensile strength. The increase in this curve is called strain hardening. During the test, the area of the cross-section decreases as the test bar is elongated |
| necking (stress-strain diagram) | cross-sectional area begins to decrease at one location on the test bar, not over its entire length. This causes a narrowing |
| safety factor (stress-strain diagram) | safety factor when designing components that will experience a higher voltage. When designing these components, we will determine the maximum permissible stress as a factor of the yield stress. We call this the safety factor v (value greater than 1). The safety factor depends on the type of load (static, dynamic). |
| ductile materials | any material that can be substantially deformed before it cracks or breaks |
| brittle materials | Materials that have little or no yield before they collapse |
| Hooke's law | 𝜎 = 𝐸𝜀 increase in stress causes a proportional increase in strain |