General discription
Silicon carbide is a resistance type heating element.and made from high density reaction-bonded silicon carbide or high purity recrystallized silicon carbide , that are extruded in the form of rods or tubes, before being bonded together by a process of re crystallization, at temperatures of over 2500°C (4530°F). The firing process ensures the creation of rods with strong uniform bonds between adjacent grains, and the particle size distribution is closely controlled to ensure optimum density and resistance to the process atmosphere.
Heating elements for element temperatures up to 1625°C (2927°F), available in a wide variety of standard sizes and geometries, or in customized designs to meet the specific needs of various processes and equipment. heating elements are capable of high power output, and may be mounted either vertically or horizontally. no special supports are required.
Grade 1 QS1
SiC heating Elements suitable for most applications in which silicon carbide elements are used. heating elements feature hot zones of high purity recrystallized silicon carbide, optimized for resistance to oxidation and common process gases. Available in rod or multi-leg designs
High density -- approximately 2.52 g/cm3 or 2.7g/cm3 to 2.8 g/cm3.This gives the Starbar very slow aging characteristics and high strength
Grade2 QS2
SiC heating elements designed for the most challenging applications where conventional silicon carbide elements are unsuitable. SiC heating elements feature hot zones of high density, low permeability, reaction-bonded silicon carbide, which is highly resistant to oxidation, and to chemical attack by process volatiles and reactive atmospheres. At 2.7 g/cm3, this high-density low-porosity element has an extremely slow aging characteristic
.
The QS M TYPE element is a heating element that has two cold ends, welded at right angles to the opposite ends of the hot section. The maximum recommended furnace temperature is 1425ºC . The element is manufactured of high density recrystallized silico carbide.
The two cold ends are low resistance silicon carbide. The diameters available range from 13 to 54mm and hot zone lengths up to 1500mm and cold ends up to 480mm long.
The QS M TYPE element is ideal for launders where terminal connections are on the top of the furnace.
The RA element has support holes in the cold end so the element can be installed with the cold ends through the roof. Cotter pins and washers are included with each element.
Item# | Diameter | Maximum Hot Zone Length | Maximum Cold End Length | Hot Zone (Eletrical Resistance) | Cold End(Eletrical Resistance) |
M-13 | 13 mm | 560 mm | 482 mm | 0.00773 Ohms/mm | 0.000387 Ohms/mm |
M-16 | 16 mm | 610 mm | 482 mm | 0.00497 Ohms/mm | 0.000248 Ohms/mm |
M-19 | 19 mm | 863 mm | 482 mm | 0.00341 Ohms/mm | 0.00017 Ohms/mm |
M-25 | 25 mm | 1220 mm | 482 mm | 0.00197 Ohms/mm | 0.000098 Ohms/mm |
M-32 | 32 mm | 1500 mm | 482 mm | 0.00134 Ohms/mm | 0.000067 Ohms/mm |
M-35 | 35 mm | 1500 mm | 482 mm | 0.00106 Ohms/mm | 0.000053 Ohms/mm |
M-38 | 38 mm | 1500 mm | 482 mm | 0.00092Ohms/mm | 0.000046 Ohms/mm |
M-44 | 44 mm | 1500 mm | 482 mm | 0.00065 Ohms/mm | 0.000032 Ohms/mm |
M-54 | 54 mm | 1500 mm | 482 mm | 0.00059 Ohms/mm | 0.00003 Ohms/mm |
Other sizes available on request
All resistance values are +/-20%. Resistance values are measured at approximately 1071ºC (1960ºF). Special high-resistance elements are also available
Easy to install through roof
Ideal for lift-off roof arrangements. All terminal connec- tions are on the top surface, and no access to the sides is required.
Ideal for narrow channels, launders and feeders. QS M PYTE elements can be fitted along the length of the unit, instead of across the width so fewer elements are required, and all terminal connections are limited to the roof, leaving the sides free for access.
Ideal for wide roofs and walls
QS M TYPE elements can be arranged in zones to improve temperature uniformity inside the furnace.
Conventional rod elements fit across the entire width or height of the furnace, and separate control zones are not possible.
QS M TYPE elements, the interior surfaces of the furnace can be divided into multiple control zones, for improved temperature uniformity and control, and improved yield of the finished products.
Physical properties
Bulk Density | 2.5-2.8g/℃m3 |
Porosity | 20% |
Thermal Conductivity | 14-19w/m ℃ |
Rupture Strength | 50Mpa(25℃) |
Specifi Heat | 1.okj/℃(25-1300℃) |
Coefficient of Thermal Expansion | 4.5x10-6(1000℃ |
OPERATING TEMPERATURES
SLIOCON CARBIDE HEATING ELEMENT USE BY ATMOSPHERE | ||||
ATMOSPHERES | TEMPERATURE LIMIT | MXXIMUM LOADING W/in2 | MXXIMUM LOADING W/cm2 | EFFECT |
CLEAN DRY AIR | 1150℃ | Maximum | Maximum | One piece Sic element can be operated at furnace control temperatures up to 1600ºC. (Maximum element temperature is 1625ºC). The three-piece Sic element is limited to 1427ºC. |
HYDROGEN | 1300℃ | 30 | 5 | An atmosphere which contains any percentage of hydrogen whatsoever will react with silicon carbide if the temperature exceeds 1300ºC. |
AMMONIA | 1300℃ | 30 | 5 | Reduces silica film, Frorm CH4 from Sic |
NITROGEN | 1370℃ | 30 | 5 | Form insulating Silicon Nitrides |
PURE OXYGEN | 1315℃ | 25 | 4 | Faster oxidization than in air. Use LMA infusion glaze cotated starbar elements, or type TW, SE,SER or SEU |
CO2 | 1500℃ | 25 | 4 | No effect,may deposit Carbon |
CO | 1540℃ | 25 | 4 | No effect |
ARGON/HELIUM | 1700℃ | Maximum | Maximum | No detrimental effect |
WATER DP 60°F | 1095℃ | 30 | 5 | Reacts with Sic to form Silicon Hydrates ,Use LMA infusion glaze coated Starbar elements, or type TW,SE,SER,or SEU. |
HALOGENS | 700℃ | 25 | 4 | Attacks Sic and SiO2 reducing |
HYDROCARBONS | 1315℃ | 20 | 3 | Hot spotting from C pick-up |
METHANE | 1315℃ | 20 | 3 | Hot spotting from C pick-up |
DRY EXOTHERMIC GAS | 1400℃ | Maximum | Maximum | Dependent on composition |
DRY ENDOTHERMIC GAS | 1250℃ | Maximum | Maximum | Dependent on composition |
VACUUM | 1205℃ | 25 | 4 | To 7 Microns -Below vaporizes Sic. Short term use only |
S and SO2 | 1315℃ | 25 | 4 | Attack Sic |
For atmospheres containing water vapor, alkali metal vapors, flux vapors, or oxygen enrichment, we recommend the use of QS3 glaze coated elements.
SERVICE LIFE
All silicon carbide elements increase in resistance during their life in operation, This characteristic of increasing in resistance is called aging. Aging is a function of the following:
•Furnace temperature
•Element surface loading in W/cm2
•Atmosphere surrounding the elements
•Mode of operation – continuous or intermittent
•Operating practices and power control methods used
•Operating and maintenance technique
As a general guide, QS SIC elements may increase in resistance at a rate of about 5 – 6% per 1000 hours operating continuously in clean air at a temperature of 1400°C ( and at about 3% per 1000 hours use at 1000°C . It should be noted that small changes in operating conditions can alter these rates considerably
INTERCHANGEABILITY
QS SIC are premier grade high performance silicon carbide elements, and we are the only high quality silicon carbide heating elements manufactured in theCHINA.
Elements can also be manufactured in special sizes and resistance values to replace elements supplied by other manufacturers in Asia and Europe.
It is important to provide the nominal electrical resistance when ordering Sic elements.
EASE OF REPLACEMENT
SIC element can be replaced while the furnace is at operating temperature. The power to the elements being changed should be shut off, the spring clips and aluminum braid released, and the old SIC removed.
The new SIC should be inserted smoothly through the hot furnace with sufficient speed to insure that the aluminum is not melted off the terminal end but not so fast as to cause thermal shock
AVAILABILITY
SIC can be shipped from stock, or two to three weeks after receipt of an order. In an emergency we may be able to produce more quickly.
CUSTOM CONFIGURATIONS
Special sizes and shapes are available. Cold ends can be different lengths. This, for example, would be applicable for furnaces with arched roofs that require longer cold ends through the roof and shorter through the floor.
Another modification is a multiple-temperature hot zone. This, for example, would be helpful to get additional heat energy into the lower, more densely loaded tunnel kiln. While this special modified hot zone may not create a specific temperature differential, it does offer a convenient way to get more or less heat energy.
SUPERIOR PERFORMANCE
SIC elements will give you superior performance due to their high density -- approximately 2.52 g/cm3 .or 2.7 g/cm3to2.8 g/cm3 ,This gives the SIC elements very slow aging characteristics and high strength.
Ordering
The minimum information required when ordering QS SIC elements is as follows:
Element type:
Diameter, mm (ØA):
Hot zone length, mm(L):
Cold end length,mm(L)
Overall length, mm (L):
Nominal resistance,( Ω):
