MIL-I-46865 Insulating Compound, Electrical, Epoxy, Colloidal Silica Filled For Potting And Encapsulation S/S By A-A-59134This specification covers an epoxy resin electrical insulating compound used for potting and encapsulating.

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MIL-I-46865B  (MI)

Spindle number                                Speed

(revolutions per minute (rpm)) Type I                                     2                                                  6

Type II                                    2                                                  6

Type III                                  3                                                  6

The viscosity shall conform to 3.2.3.

4.7.4.4  Storage life.  A sufficient amount of premix in an original unopened container shall be stored under the conditions specified in 3.2.4.  At the end of the storage period, the premix shall be subjected to all the test requirements specified herein.  The contractor's certification of compliance certifying to the storage life requirements (see 3.2.4) may be accepted during the storage period.

4.7.4.5  Porosity.  A cured sample shall be cut or broken and then examined under 10 power magnification to determine conformance to the requirement of 3.3.1.

4.7.4.6  Hardness.  Hardness shall be determined on a cured specimen at ambient temperature in accordance with ASTM D 2240 and shall conform to the requirement of 3.3.2.

4.7.4.7  Flexibility.  Two strips of cured material 0.125 inch thick, 0.25 inch wide, and 3.0 inches long shall be bent over a 2-inch diameter mandrel and visually examined for conformance to the requirement of 3.3.3.  Retest, if necessary, shall be conducted in accordance with paragraph 4.7.4.9.

4.7.4.8  Insulation resistance.  Testing shall be at ambient temperature in accordance with ASTM D 257, and the insulation resistance shall conform to the requirement in 3.3.4.

4.7.4.9  Retest.  An acceptance sample of material which has passed the acceptance tests need not be retested until its shelf life has expired.  At such time one container shall be selected at random from the overage acceptance sample.  The material shall be thawed and examined for evidence or partial cure by observing its ability to be extruded.  If material passes this phase, pot life test shall be conducted in accordance with 4.7.4.2 and samples for cure shall be prepared simultaneously.  If samples cure satisfactorily, they shall be tested for hardness in accordance with 4.7.4.6 and flexibility in accordance with 4.7.4.7.  Material which successfully passes retest shall be updated for one month from completion date of tests.  Material shall not subsequently be retested, updated, or used.

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