Fundamentals of materials science part 2 Flashcards
materials with mechanical properties dependent of loading rate and with viscous and elastic behavior are what?
viscoelastic
Materials with mechanical properties independent of loading rate are what?
elastic
the resistance of a fluid to flow and is equal to the shear stress/shear strain rate is what?
viscosity
what is hardness?
resistance to permanent surface indentation or penetration
What is friction?
the resistance between contracting bodies when one moves relative to another
What is wear?
is loss of material resulting from removal and relocation of materials through the contract of two or more materials
Adhesive wear
formation and disruption of microjunctions
corrosive wear
secondary to physical removal of protective layer and it is related to the chemical activity of the wear surfaces
surface fatigue wear
free particles with small areas of contact contribute to high localized stress and produce surface cracks
abrasive wear
involves a harder material cutting into a softer material
what are colloids
substances that consist of two or more phases, with the units of at least one of the phases having a dimension slightly greater than simple molecular size.
Highly dispersed system of the fine dispersions
eg. gels, films, emulsion, foams
what is a sol
a solution, that is made up of colloidal particles dispersed in a liquid
what is a gel
when suitable amount of chemicals to the sol that the solution becomes jelly like
adsorption
a liquid or gas adheres to the surface of a solid or liquid firmly by attachment of molecules, decreases their surface free energy
absorption
the substances diffuses into the solid material by a diffusion process, and the process is characterized by concentration of molecules at the surface
soprtion
when adsorption and absorption exist at the same time and it is unknown which one predominates
what is wetting
the tendency to spread on the surface of the solid
the eye can distinguish differences in how parameters of color?
3, dominant wavelength, luminous reflectance, and excitation purity
what is hue
the colors between violet and red on the wavelength spectrum. eg: green, yellow, orange light
value
the quality of lightness or darkness. That is black is a dark value or low value. White is a light value or high value
chroma
the quality of a colors purity, intensity or saturation
what do rough surfaces appear lighter than smooth surfaces?
because more white light is reflected back on rough surfaces and dilutes the color
what is metamerism
colors that have the same value under a particular light source but under another source they look different
flourescence
the emission of luminous energy by a material when a beam of light is shone on it
opactiy
a property of materials that prevents the passage of light, when all colors are absorbed it is black and when they are all reflected it is white
translucency
a property of substance that permits the passage of light but disperses the light, so objects cannot be seen through the material
opalescent
materials that are able to scatter shorter wavelengths of light.
eg. enamel
what is heat of fusion
the heat in calories or joules, required to convert 1 gram of material from solid to liquid state at the melting temperature
thermal conductivity
is the quality of heat in calories or joules, per second passing through a body 1 cm thick with a cross-section of 1cm squared when the temperature difference is 1 degree celcius
specific heat
the quantity of heat needed to raise the temperature of 1 gram of the substance 1 degree celcius
thermal expansion
the measure of change in length of material for a 1 degree change in temperature
dielectric
a material that provides electrical insulation
electromotive force
the voltage developed by any source of electrical energy
galvanism
results from a difference in potential between dissimilar fillings in opposing or adjacent teeth, resulting in current running through the pulp when the two teeth touches due to a short circut
electrochemical corrosion
corrosion that is accompanied by a flow of electrons between cathodic and anodic areas on metallic surfaces
zeta-potential
the potential difference existing between the surface of a solid particle immersed in conducting liquid and the bulk of the liquid
