Dow 997 Varnish

Dow 997 Varnish Datasheet
  • Description for Dow 997 Varnish

    Long service life; little tendency to bubble; flexible cure schedule.

    *See Terms of Use Below

    Application Type Bond, Coat
    1 Part or 2 Part 1 Part
    Material Form Liquid
    Industry Electrical coil, Electrical equipment, Motor stator coils, Motors, Transformers, Generator coils, Solenoids, Transformers windings, Generators
    Manufacturer Dow
    Chemistry Xylene, Silicone resin
    Cure Method Solvent
    Cure Temperature (°C) >20, 250, 200, 200, 200, 200, 200
    Cure Time (min) 360, 180, 360, 30, 240 to 480, 120, 120
    Viscosity (cPs) 90 to 120
    Color Dark brown
    Key Specifications Mil-Spec (United States Military Standard): MIL-I-24092B
  • Technical Data for Dow 997 Varnish

    Overview
    • Application Type
    • 1 Part or 2 Part
      • 1 Part or 2 Part - 1 Part
    • Material Form
      • Liquid
    • Industry
      • Electronics - Electrical equipment, Solenoids, Generators
      • Coils - Electrical coil, Generator coils
      • Transformers - Transformers windings
      • Motors - Motor stator coils
    • Chemistry
      • Other - Xylene
      • Silicone - Silicone resin
    • Application Method
      • Dip
    • Cure Method
      • Solvent
    • Color
      • Brown - Dark brown
    • Key Specifications
      • Mil-Spec (United States Military Standard): I-24092B - MIL-I-24092B
    Specifications
    Cure Specs
    Cure Temperature (°C) >20, 250, 200, 200, 200, 200, 200 Test Method
    Cure Time (min) 360, 180, 360, 30, 240 to 480, 120, 120 Test Method
    Viscosity (cPs) 90 to 120 Test Method
    Bond Strength
    General Bond Strength (psi) Good, 9 (lbs), 16 (lbs), 25 (lbs) Test Method
    Material Resistance
    Moisture/Humidity Resistance Moisture/humidity resistance
    Conductivity
    Dissipation Factor 0.01000, 0.02000, 0.00700, 0.01000 Test Method
    Dielectric Strength (V/mil) Good, 2,000, 1,500 Test Method
    Dielectric Constant 3.10, 3.20, 2.98, 3.10 Test Method
    Thermal Conductivity (W/m°K) 0.15 Test Method
    Volume Resistivity (O) 2e14 (ohms/cm), 1e14 (ohms/cm) Test Method
    Hardness
    Flexibility Flexible
    Other Properties
    Specific Gravity 1.000 Test Method
    Flash Point (°F) 80.6 Test Method
    % Solids (%) 50 Test Method
    Business Information
    Shelf Life Details When stored at or below 25 C (77 F), DOW CORNING 997 varnish has a shelf life of 12 months from date of shipment from Dow Corning.
    Shelf Life Type From date of shipment
    Shelf Life (mon) 12
  • Best Practices for Dow 997 Varnish

    *See Terms of Use Below

    1. Curing

      Curing time and temperature vary with the size and complexity of the equipment, the properties desired in the varnish film and the characteristics of the curing oven.

      Curing time should be measured from the time both the oven and the impregnated equipment reach the curing temperature. When establishing curing schedules for specific equipment, follow these general rules: Final cure temperature should be at least 20 C (68 F) above the maximum operating temperature of the impregnated equipment.

      When maximum bond strength is required, equipment should be given a final cure at 250 C (482 F) for at least 6 hours.

      Equipment impregnated with DOW CORNING 997 varnish can usually be placed in ovens at temperatures between 150-200 C (302-392 F) without the appearance of bubbles in the varnish film. Equipment that is to be cured at 250 C (482 F), however, should be given an initial bake of 2 to 4 hours at 150-200 C (302-392 F). Small or complex equipment that will be cured at temperatures above 150 C (302 F) should be given a preliminary bake of 1 hour at 100-150 C (212-302 F).

      Immersion time must be kept to a minimum to prevent solvent damage to insulating components.

  • Comparable Materials for Dow 997 Varnish

    *See Terms of Use Below

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Cure Temperature Test Methods
Cure Temperature Cure Time Test Method
>20°C
250°C
200°C
200°C
200°C 4 to 8 hours at 200 C (392 F).
200°C 2 hours at 200 C (392 F), followed by 3 to 7 hours at 225 C (437 F)
200°C 2 hours at 200 C (392 F), followed by 2 to 6 hours at 250 C (482 F)
Cure Time Test Methods
Cure Time Test Method
360 min
180 min
360 min
30 min
240 to 480 min 4 to 8 hours at 200 C (392 F).
120 min 2 hours at 200 C (392 F), followed by 3 to 7 hours at 225 C (437 F)
120 min 2 hours at 200 C (392 F), followed by 2 to 6 hours at 250 C (482 F)
Viscosity Test Methods
Viscosity Test Method Temperature
90 to 120 cPs CTM 0050 25°C
General Bond Strength Test Methods
General Bond Strength Cure Time Cure Temperature Test Temperature Test Method
Good 360 min 150°C 25°C Helical wound coils of No. 18 AWG aluminum wire were impregnated with Dow Corning 997 varnish. The bond strength was determined as the number of pounds required to break this coil as a simple beam. This test is a functional measure of the varnish film strength.
9 (lbs) 360 min 200°C 25°C Helical wound coils of No. 18 AWG aluminum wire were impregnated with Dow Corning 997 varnish. The bond strength was determined as the number of pounds required to break this coil as a simple beam. This test is a functional measure of the varnish film strength.
16 (lbs) 360 min 250°C 25°C Helical wound coils of No. 18 AWG aluminum wire were impregnated with Dow Corning 997 varnish. The bond strength was determined as the number of pounds required to break this coil as a simple beam. This test is a functional measure of the varnish film strength.
25 (lbs)
Dielectric Constant Test Methods
Dielectric Constant Temperature Test Method
3.10 25°C Dielectric constant, 100 Hz, CTM 0112, 6 hours at 200 C (392 F), as supplied
3.20 25°C Dielectric constant, 100 Hz, CTM 0112, 6 hours at 200 C (392 F), after 24 hrs immersion in distilled water
2.98 25°C Dielectric constant, 100 KHz, CTM 0112, 6 hours at 200 C (392 F), as supplied
3.10 25°C Dielectric constant, 100 KHz, CTM 0112, 6 hours at 200 C (392 F), after 24 hrs immersion in distilled water
Dielectric Strength Test Methods
Dielectric Strength Temperature Test Method
Good
2,000 V/mil 200°C CTM 0114, 6 hours at 200 C (392 F), as supplied
1,500 V/mil 200°C CTM 0114, 6 hours at 200 C (392 F), after 24 hrs immersion in distilled water
Dissipation Factor Test Methods
Dissipation Factor Temperature Test Method
0.01000 25°C Dissipation factor, 100 Hz, CTM 0112, as supplied, 6 hours at 200 C (392 F)
0.02000 25°C Dissipation factor, 100 Hz, CTM 0112, after 24 hrs immersion in distilled water, 6 hours at 200 C (392 F)
0.00700 25°C Dissipation factor, 100 KHz, CTM 0112, as supplied, 6 hours at 200 C (392 F)
0.01000 25°C Dissipation factor, 100 KHz, CTM 0112, after 24 hrs immersion in distilled water, 6 hours at 200 C (392 F)
Thermal Conductivity Test Methods
Thermal Conductivity Temperature Test Method
0.15 W/m°K 200°C CTM 0224
Volume Resistivity Test Methods
Volume Resistivity Temp (°C) Test Method
2e14 (ohms/cm) 200°C CTM 0249, as supplied, 6 hours at 200 C (392 F)
1e14 (ohms/cm) 200°C CTM 0249, after 96 hrs at 23 C (73 F) and 96 percent RH., 6 hours at 200 C (392 F)
Flash Point Test Methods
Flash Point Test Method
27.0°C CTM 0021A
% Solids Test Methods
% Solids Test Method
50 % CTM 0208, after 3 hrs at 135 C (275 F), percent
Specific Gravity Test Methods
Specific Gravity Temperature Test Method
1.000 25°C CTM 0001A