Chapter 11 Questions

What makes ceramics different engineering materials like metals and plastics?

- Scratch resistance in ceramics is greater than in metals and plastics. - Smoothness is ceramics is higher when compared to metals and plastics. - Ceramics are more brittle in nature as compared to other engineering materials. - Ceramics are lighter than metals, and heavier than polymers. - Ceramics material is opaque, but plastics and metals can be formed into transparent, semi-transparent, or opaque forms.

Describe four uses for cemented carbides and why they were chosen over other materials for those applications.

- Tooling equipment because they have the highest hardness than any other tooling material. - Abrasives due to their high hardness and density when compared to other metals like steel. - punching operation, as punches and dies, due to their high density and hardness. - cutting tools and saw blades due to their higher hardness than steel or any other tooling material.

The compressive strength of aluminum oxide is how many times the compressive strength of aluminum 6061T6? A. 10 B. 3 D. 0.5 F. 0.3

A. 10

Which is the stiffest? A. soda lime glass B. rigid vinyl C. Plexiglas (PMMA) D. polycarbonate E. cellulose acetate F. polyethylene

A. soda lime glass

How hard is aluminum oxide compared with hard steel (60 HRC)?

Aluminum oxide is a ceramic material with a hardness of 210 HRC which is more than three times the hardness of hardened steel whose hardness is 60 HRC.

Which of the following is a cermet? A. WC/Co B. Tic/steel C. WC/10CoCr D. carbon/graphite

B. TiC/steel

Which of the following is the hardest? A. a file B. a cemented carbide tool bit C. a zirconia wear part D. a cold chisel E. marble F. granite

B. a cemented carbide tool bit

Which of the following is used as a binder for cemented carbides? A. steel B. cobalt C. chromium D. silver E. copper F. glass

B. cobalt

Ceramics can be all but A. glasses B. oxides C. intermetallics D. nitrides E. carbides

B. oxides

Silicon carbide will expand how many times the expansion of steel upon being heated to 500 C? A. one tenth B. five times C. one half D. two times

C. one half

Which of the following are ceramic microconstituents? A. inclusions B. porosity C. second phases D. binders E. covalent bonds F. cobalt

C. second phases

Why are many ceramics very corrosion resistant?

Ceramics are available in nature in the form of non reactive oxides, nitrides and crystal structures which are highly resistant to corrosion.

Why are ceramics brittle?

Ceramics are inorganic solid compounds composed of metallic and non metallic elements bonded by strong ionic or covalent bonds. Brittleness is the material property of failure of the metal, without undergoing any plastic deformation, when subjected to stress.

What is concrete?

Concrete is a composite material made up of sand, coarse filler, and cement. Here, cement is used as a binder and rock fragments are employed as filler materials. Cement bonds the sand across the filler rocks making them like ceramic materials.

The deflection of a cemented carbide boring bar is how many times that of a steel boring bar that same size? A. 2 B. 3 C. 0.5 D. 0.33 E. 0.72 F. 0.9

D. 0.33

Which of the following is NOT a ceramic? A. silica glass B. aluminum oxide C. yttria D. magnesia E. silicon carbide F. cemented carbide

D. magnesia

Which of the following is NOT a type of glass? A. Vycor B. silica glass C. soda time glass D. crystal E. Pyrex F. Plexiglas

F. Plexiglas

Which of the following is a ceramic? A. granite B. Waterford crystal C. soapstone D. marble E. agate F. alumina

F. alumina

What is a glass and how is it different from a ceramic?

Glass is an amorphous inorganic solid materials. It is manufactured by using silica sand and sodium carbonate and calcium oxide are added to make the glass durable. Ceramics are partly crystalline inorganic solids. Glass ceramics have better mechanical properties compared to glass.

What type of crystal structure do ceramics have?

Most of the ceramics have polycrystalline structure in which crystallites of different sizes are randomly oriented in different directions.