Sintering Furnaces and Sintering Atmosphere

Question 1

Intermittent kiln

Answer 1

Mostly gas fired or electric resistance

Tunnel kilns for mass production

Question 2

Continuous kiln

Answer 2

Atmosphere is usually air and oxidizing
Non oxides (SiC) require controlled atmosphere (Ar or N2)

Question 3

Microwave Kilns

Answer 3

Short cycle and uniform heating of irregular produce due to internal heating by microwaves
Higher energy efficiency as heating of kiln itself not required
Environmentally friendly due to no noise or exhaust gas
Automatic firing control due to quick response of temperature control

Question 4

Tunnel Kiln (similar to belt furnace)

Answer 4

Ceramic pieces placed on setters and stacked
Hot gas circulates between articles
Travels from cold end to hot zone
Heat energy used to preheat ceramic
Used in refractory whitewall production

Question 5

Factors affecting sintering atmosphere selection

Answer 5

Type of material to be sintered
Targeted properties
Types of furnaces available
Money
Availability of gas

Question 6

Function of sintering atmosphere

Answer 6

Prevent chemical reactions between environment and material
Cleaning and purification of component
Addition or removal of alloying element
Protection against loss of alloying element

Question 7

Commercially used sintering atmospheres

Answer 7

Hydrogen
Ammonia
Nitrogen (with or without additions)
Hydrocarbons
Inert gases
Vacuum