SUCCESS^®  MoSi₂ heating elements

        Highlights of Quality:

          One piece element!

          No welding section between heating and cold zones!

           Maximum surface heating temperature 1960℃

           Maximum operating temperature 1850℃

            Withstand impact of electric-shock

           could be used Intermittently!

           Smaller temperature coefficient of resistance!

           No surface layer peeling off!

           High strength at room temperature!

           Hardly deformation at high temperature!

           Hardly aging!

           A revolution in thermal ceramic industry!

HIGH-TECH PRODUCT:

SUCCESS^® heating elements are made by high-tech procedure ultra dry-press and consist of unique micro-crystal structures, SUCCESS® heating element is in one piece and there is no welding part between cold and heating zones. Therefore, it eliminates internal stress, crystal stress and sudden changes of material characters between cold and heating zones as most elements have experienced.

SUCCESS® heating element is the only high-tech product with one continuous structure element in the world. SUCCESS® heating element’s unique structure avoids many disadvantages of common elements have, such as brittleness, poor strength, localieed over heating, protective layer flakes off and contamination, etc.

CHARACTERISTICS:

SUCCESS^® heating elements can withstand the furnace temperature to maximum 1860℃(3380℉) with aging coefficient less than 0.55% per year. It could also replace SiC elements at lower temperature (below 1300℃) and its mechanical strength dose not change.

Due to its unique microstructure, SUCCESS® heating elements could be used in horizontal position without bending or deformation at high temperature (1700℃). In addition , it allows to increase and decrease the temperature by switching on or off the furnace arbitrarily at any temperature below the maximum allowable loading current.

  At high temperature and oxygenic atmosphere a semiconductor protective layer of quartz glass is formed on the surface. This layer has high anti-oxidation resistance and ability to keep itself clean. Therefore, it is an ideal heating element used for oxygenic atmosphere. It can be widely used in metal and steel, sentering, glass, ceramic and crystal industries, especially for producing super ceramic, precise construction ceramic-metal, optical fiber and super alloy steel.

  COMPOSITION:

SUCCESS^® heating elements is a high-tech product made from dense ceramic-metal of molybdenum disilicide(MoSi₂) crystal be ultra dry-press process and has unique microstructure, MoSi₂ is a specific ceramic material that can withstand oxidation at high temperature. MoSi₂ heater is an electric heating element for high temperature furnaces.

SPECIFICATION:

SUCCESS^® heating elements can be made in various shapes, such as straight-line, U (2-shank), W (4-shank), and helix, etc. The wider section is “cold zone”. The thinner section is “heating zone”. There is a taper transition between cold and heating zones. Although there are dimensional differences among cold, heating and taper zones, the material and microstructure are identical. They have the same mechanical strength.

  The dimensions of most common U-shape heating element are listed in Table 1.

Figure 1 shows the dimensions of a U-shape heating element.

  Table 1. Dimension of U-shape SUCCESS^® heating element (mm)

            Figure 1. SUCCESS^® U-shape heating element

TECHNICAL CHARACTERISTICS AND SPECIFICATIONS:

Table 2 . show the main technical data for SUCCESS^® heating elements compare with welding Super heating elements.

      Figure 2. Resistance – temperature of SUCCESS^® heating elements

INSTRUCTION FOR INSTALLTION AND USE OF SUCCESS^® HEATING ELEMENTS:

 (A). Use of SUCCESS^® heating elements for the first time:

When a brand new SUCCESS^® heating elements has been installed, it must form a metal glass protective layer on the surface should never fall or flak off later. The method to form the protective layer is simple; First choosing the recommended high temperature operating current based on the diameters of heating zone and switches on to keep the temperature for about two hours. Second, reducing the current to half and keeping this state about half hour to one hour and shut off the electricity. A metal glass protective layer will be formed on the element surface. From now on, the protective layer should not fall or flak no matter how the temperature rises or drops.

The recommended maximum operating currents are:

    φ6/φ12   series→ 160A;

    φ9/φ18   series→ 340A;

    φ12/φ24  series→ 560A.

If a brand new SUCCESS^® heating elements is used for an emergency replacement, the metal-glass protective layer can also be formed by reducing temperature gradually operation.

 (B). Selective values for surface load :

If is essential to choose a correct surface load (w/cm²) for prolonging service life of the elements and improving efficiency of the furnace. Refer to Figure 3 to select right surface load.

  Figure 3.  Select right surface load of SUCCESS^® U-shape heating element

        explain: ■ select right surface.

(C) Power and Current Calculation:

 Pro SUCCESS^® heating elements, the power (P) and current (I) of heating zone could be calculated as follows;

         P(w)=ωπdLe/100

         I(A) = 0.5π(d³ω10/ρ_r)^1/2

Where:  P: Heating zone power (W)

        ω: Heating zone surface load (W/cm²); It can be determined from Fig.3 or estimated as 20~25 (the common value is 20)

        d: Heating zone diameter (mm)

        Le: Heating zone length (mm)

        I: Heating zone current (A)

        ρ_r: Heating zone heat-state resistivity (Ωmm²/m)

For SUCCESS^® heating elements, ρ_r can be calculated by:

        ρ_r = 0.012 (T – T₀)ρ₀

where:  T : Heating zone operating temperature (℃)

        T₀ : Reference temperature or room temperature (℃)

        ρ₀ : Resistivity at room temperature (2.29 Ωmm²/m)

  The power consumed by cold zone can be omitted when calculation is for a single element, If elements are placed vertically, the cold zones consume about 10% of the power that heating zone consumed. If the elements are used in horizontal position, the cold zones consume 5% of the power of that heating zone consumed.

  (D). Calculation of number of elements needed:

For SUCCESS^® heating elements, the number of elements needed can be calculated by:

       P_t = nP = (150 ~ 200)V^2/3

Where:   P_t : Total power of furnace (kW)

         P : Heating zone power (W)

         n : Number of heating elements

         V : Volume of furnace (m³)

For tri-phase-electricity furnace, the number of elements should be 3n.

In above equation, the coefficient (150 ~200) is depending on the rate of temperature changes of the furnace. The higher the rate of temperature change is required, the larger the coefficient value should be used.

(E). The suitability of SUCCESS^® heating elements in various atmospheres:

SUCCESS^® heating elements can be used in almost any furnace atmosphere conditions including but not limited to air, CO₂, ammonia and petroleum (Table 6) due to small amount of special additives. Most competitive molybdenum disilicide heating elements could not stand for long time in varied acids, alkali, reducing and humid atmospheres. Table 6 lists the maximum operating temperature for SUCCESS^® heating elements and parallel with welding Super heating elements.

Table 6. The maximum operating temperature in various atmospheres

  (F). The factors damaging SUCCESS^® heating elements under continuous operation:

l         Current: The heating elements will be damaged within 20 minutes under the following currents:

φ6/φ12 series → 260A

    φ9/φ18 series → 580A

    φ12/φ24 series → 1000A

SUCCESS^® heating elements should be used at 80% of above current conditions.

l         Temperature: The elements will be damaged within 10 minutes at 2250℃.

SUCCESS^® heating elements should be used under 1800℃ (80% of 2250℃).

l         Vacuum: When the atmospheric pressure is less than 10^-5mmHg, the cooling condition will be unfavorable in furnace chamber. The operating temperature should be below 1200℃; The surface load should be below 15W/cm²; The operating current should be 1/3 or less of the maximum current.

l         The rate of temperature changing:  SUCCESS^® heating elements heating zone may be broken at the following heating and cooling rate:

        φ6/φ12 series →300℃/min

φ9/φ18 series →220℃/min

φ12/φ24 series →140℃/min

Temperature change rate should be below 50% of the above broken temperature change rates.

* Bending deformation: SUCCESS^® heating elements shouldn’t be deformed larger than 0.15% of the length of its heating zone. Care must be taken during installing and operation to avoid artificial bending.