Fundamentals of materials science part 2

Question 1

materials with mechanical properties dependent of loading rate and with viscous and elastic behavior are what?

Answer 1

viscoelastic

Question 2

Materials with mechanical properties independent of loading rate are what?

Answer 2

elastic

Question 3

the resistance of a fluid to flow and is equal to the shear stress/shear strain rate is what?

Answer 3

viscosity

Question 4

what is hardness?

Answer 4

resistance to permanent surface indentation or penetration

Question 5

What is friction?

Answer 5

the resistance between contracting bodies when one moves relative to another

Question 6

What is wear?

Answer 6

is loss of material resulting from removal and relocation of materials through the contract of two or more materials

Question 7

Adhesive wear

Answer 7

formation and disruption of microjunctions

Question 8

corrosive wear

Answer 8

secondary to physical removal of protective layer and it is related to the chemical activity of the wear surfaces

Question 9

surface fatigue wear

Answer 9

free particles with small areas of contact contribute to high localized stress and produce surface cracks

Question 10

abrasive wear

Answer 10

involves a harder material cutting into a softer material

Question 11

what are colloids

Answer 11

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

Question 12

what is a sol

Answer 12

a solution, that is made up of colloidal particles dispersed in a liquid

Question 13

what is a gel

Answer 13

when suitable amount of chemicals to the sol that the solution becomes jelly like

Question 14

adsorption

Answer 14

a liquid or gas adheres to the surface of a solid or liquid firmly by attachment of molecules, decreases their surface free energy

Question 15

absorption

Answer 15

the substances diffuses into the solid material by a diffusion process, and the process is characterized by concentration of molecules at the surface

Question 16

soprtion

Answer 16

when adsorption and absorption exist at the same time and it is unknown which one predominates

Question 17

what is wetting

Answer 17

the tendency to spread on the surface of the solid

Question 18

the eye can distinguish differences in how parameters of color?

Answer 18

3, dominant wavelength, luminous reflectance, and excitation purity

Question 19

what is hue

Answer 19

the colors between violet and red on the wavelength spectrum. eg: green, yellow, orange light

Question 20

value

Answer 20

the quality of lightness or darkness. That is black is a dark value or low value. White is a light value or high value

Question 21

chroma

Answer 21

the quality of a colors purity, intensity or saturation

Question 22

what do rough surfaces appear lighter than smooth surfaces?

Answer 22

because more white light is reflected back on rough surfaces and dilutes the color

Question 23

what is metamerism

Answer 23

colors that have the same value under a particular light source but under another source they look different

Question 24

flourescence

Answer 24

the emission of luminous energy by a material when a beam of light is shone on it

Question 25

opactiy

Answer 25

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

Question 26

translucency

Answer 26

a property of substance that permits the passage of light but disperses the light, so objects cannot be seen through the material

Question 27

opalescent

Answer 27

materials that are able to scatter shorter wavelengths of light.
eg. enamel

Question 28

what is heat of fusion

Answer 28

the heat in calories or joules, required to convert 1 gram of material from solid to liquid state at the melting temperature

Question 29

thermal conductivity

Answer 29

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

Question 30

specific heat

Answer 30

the quantity of heat needed to raise the temperature of 1 gram of the substance 1 degree celcius

Question 31

thermal expansion

Answer 31

the measure of change in length of material for a 1 degree change in temperature

Question 32

dielectric

Answer 32

a material that provides electrical insulation

Question 33

electromotive force

Answer 33

the voltage developed by any source of electrical energy

Question 34

galvanism

Answer 34

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

Question 35

electrochemical corrosion

Answer 35

corrosion that is accompanied by a flow of electrons between cathodic and anodic areas on metallic surfaces

Question 36

zeta-potential

Answer 36

the potential difference existing between the surface of a solid particle immersed in conducting liquid and the bulk of the liquid