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| An object characterized by resistance to deformation and changes of volume. |
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| Characterized by free movement of the constituent molecules among themselves but without the tendency to separate. |
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| A fluid (as air) that has neither independent shape nor volume but tends to expand indefinitely |
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| the force per unit area as the material is subjected to load. |
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| forces on an object are directed toward one another; malleability |
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| forces on an object are directed away from one another; ductility |
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| forces on an object are directed in such a manner to twist, rotate or deform the object by sliding one part parallel to the other; harmful to the human dentition |
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| a measure of the change in length of the sample as a result of an applied force. |
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| Modulus of Elasticity/Young's |
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Definition
| stress/strain until no longer proportional; also a measure of a materials stiffness |
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| stress proportional to the strain; at stresses that exceed this the object no longer retains its original shape |
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| strain associated with stress at the proportional limit |
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| a small but permanent dimensional change when ratio of stress and strain is no longer equal |
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| stress at which a material exhibits a specified limiting deviation from proportionality of stress to strain; permanent strain is arbitrarily selected; |
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| What is the conventional offset of yield strength? |
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Definition
| ability of a material to withstand permanent deformation under tensile stress without fracture |
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| ability of a material to withstand permanent deformation under compressive stress without fracture |
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| the amount of deformation a material can withstand without rupture when a TENSILE stress is applied |
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| the amount of deformation a material can withstand without rupture when a COMPRESSIVE stress is applied |
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| The ratio of axial to lateral strain within the elastic range; reduction of cross-section is proportional to the elongation during elastic deformation |
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| a degree of hotness or coldness measured on a definite scale: Fahrenheit, Celsius, Kelvin |
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| The heat in calories, or joules (J), required to convert 1g of a material from solid to liquid state at the melting temperature L = Q/m |
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| The quantity of heat in calories or joules (J), per second passing through a body 1-cm thick with a cross section of 1cm2 when the temperature difference is 1 Celsius degree |
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| have a thermal conductivity similar to dentin and enamel |
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Definition
| The quantity of heat needed to raise the temperature of 1g of the substance 1 Celsius degree |
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Definition
A measure of transient heat flow and is defined as the thermal conductivity, K, divided by the product of the specific heat, Cp, times the density, r:
D = K / (Cp r) mm2/sec
the rate at which a body with a nonuniform temperature approaches equilibrium |
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Term
| linear coefficient of thermal expansion |
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Definition
the measure of change in length per unit length when the temperature is raised 1 Celsius degree higher.
Formula: (lt2 – lt1 / lt1) / (t2 – t1) |
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Term
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Definition
dominant color of an object
R O Y G B I V |
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Term
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Definition
| lightness of color on a scale of 1 – 10; 1 = black, 10 = white |
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| intensity of color on a scale of 1 – 10; 1 = unsaturated, 10 = saturated |
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Definition
| What is HVC of natural teeth? |
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Definition
| In what range of the color spectrum is the eye most sensitive to light? |
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Definition
| light passes completely through an object |
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| light not allowed to pass at surface or incompletely below surface |
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| light entering does not leave |
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| colors under a fluorescent light source differ under a natural light source |
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| emission of visible light as a result of absorption of radiation from some other source |
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| conductivity or specific conductance |
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Definition
| Ability of a material to conduct an electric current |
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Definition
| Ability of a material to repel an electric current is specific resistance or resistivity |
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| permanent deformation under constant load in CRYSTALLINE materials |
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| permanent deformation under constant load in AMORPHOUS materials |
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Definition
| the energy required to deform a material permanently; the area beneath the linear portion of the stress-strain curve |
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| the energy necessary to fracture a material; the total area beneath the stress-strain curve |
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| material resistance to indentation; generally reported in KNOOP numbers |
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| Vickers Hardness Tester 136*Diamond Pyramid |
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Definition
| Measures small areas; very hard materials |
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| Micro-indentation tests; thin plastic/metal sheets; brittle materials |
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| study of the flow of liquids |
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| material will become thin when stirred but are thick on standing. |
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| an ideal adhesive has a contact angle that approaches, but can never attain ZERO DEGREES |
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| The penetration of liquids into narrow crevices |
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| small electric currents created when two dissimilar metals are present in the oral cavity |
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Definition
| chemical or electrochemical attack of the environment on a pure metal or an alloy |
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| electrochemical corrosion |
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Definition
| combination of chemical reaction and flow of electric current; oxidation (loss of electrons at surface) of metals |
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Definition
| variation in composition of metals on a single surface; eutectic alloys in combination with other alloys |
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| nonuniform surface corrosion |
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Definition
| occurs when final finishing of metal creates surface stress causing a battery (corrosion) to form between the stressed metal and the saliva |
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| concentration cell corrosion |
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Definition
| metals exposed to two solutions, or electrolytes, at the same time |
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Definition
| gypsum ground and heated until H2O is removed |
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| fluffy, porous, least dense |
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| more crystalline, higher density |
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| the densest of the raw gypsum |
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