Mica Specs.

Spruce Pine Mica Company
CALL US  +1-828-765-4241

ASTM

D-351
CLASS
FED SPEC

HHI-536

TYPES

COMMERCIAL

CLASS

USES

INDICATOR

OF COMPARITIVE VALUE

Chart of Mica Qualities


SUPERFINE


V-1
NMC
Clear
Microwave windows, large transmitter capacitors, special high quality optics, air regulating diaphragms, Geiger-Muller counter windows, metalized resistance cards, bolometers.
100
V-2
NMS
Clear& Slightly Stained

65


CAPACITOR QUALITY


V-3
NMF
FAIR STAINED
Capacitors for radio transmitters and general electronic purposes. Mica has low power loss and high “Q” values.
45
V-4
NMG
GOOD STAINED

Capacitors for radio receivers. “Q” is slightly lower. Excellent for all average applications in radio and electronic work. 
32


RADIO TUBE QUALITY


V-5
NMSA
STAINED A

High quality radio tube spacers, lowest quality for used for small capacitors
14
V-6
NMSB
STAINED B

12


CLEAR ELECTRIC


V-7
NMH
Heavy Stained
Thermostat insulators, lower quality tube spacers, fuse windows, neon electrodes, heating elements.  Highest quality for needed for low voltage applications.
10


SPOTTED ELECTRIC


V-8
NMDB
Black Dotted
Appliances, 110/220-volt insulation, transformer layer insulation.
5
V-9
NMBS
Black Spotted
Dots and Spots are non-conductive; however, mica has a small amount of surface leakage.
4


STAINED ELECTRIC


V-10
NMBS
Black Stained
Motors, appliances and resistors, Stains are conducting at high voltage and more surface leakage. 
3

 
ASTM and Federal Specifications may be used at any time as we are able to furnish certificate of compliance on any products fabricated. Following are some of the applicable specifications.

ASTM-D-351 – Visual Quality Mica

ASTM-D-748 – Mica for Fixed Capacitors

HH-I-536 – Visual Quality Mica

HH-I- 538 – Electrical Pasted Mica


Properties of Mica (MUSCOVITE, Compiled by the U.S. Bureau of Mines)



Mechanical

Density:               Gr./Cu. Cm        .............................................................................................................................................................   2.6-3.2

                                Lb./Cu. Ft.           ...........................................................................................................................................................  160-200

Hardness, Mohs               ...........................................................................................................................................................................  2.0-3.2

Cleavage               ..........................................................................................................................................................................  Basal, Eminent

Crystal Structure           ....................................................................................................................................................................  Monoclinic

Max Temperature with no decomposition  ..................................................................................................................................  400-500⁰C


Specific Heat(25⁰C)  .............................................................................................................................................................................  .206-.209

Thermal conductivity perpendicular to cleavage:

                                                Cal./Sq. Cm./Sec./Cm./⁰C  .........................................................................................................................  16x10-⁴

                                                B.T.U./ Sq. Ft./Hr./In. ⁰F ....................................................................................................................................  4.6

Coefficient of expansion per ⁰C perpendicular to cleavage:

                                                20⁰-100⁰C  .................................................................................................................................  15x10-⁶-- 25x10-⁶

                                                100⁰-300⁰C  ..............................................................................................................................  15x10-⁶ -- 25x10-⁶

                                                300⁰-600⁰C  ...............................................................................................................................  16x10-⁶ -- 36x10-⁶

Coefficient of expansion per ⁰C parallel to cleavage:

                                                0⁰-200⁰C  .........................................................................................................................................  8x10-⁶ -- 9x10-⁶

                                                200⁰-500⁰C  .................................................................................................................................  10x10-⁶-- 12x10-⁶

Tensile Strength, P.S.I.  ............................................................................................................................................................  37,000-43,000

Modulus of elasticity  ................................................................................................................................................................................  25x10⁶

Electrical

Dielectric Constant  ....................................................................................................................................................................................  6.5-9

Dielectric Strength (highest Qualities 1-3 mils thick), Volts/Mil  ....................................................................................  6,000-3,000

Power Factor at 25⁰C (77⁰F) (highest qualities), percent:

                                                60 cycles  ....................................................................................................................................................  0.08-0.09

                                                1 megacycle  ..............................................................................................................................................  0.01-0.02

Resistivity, Ohm-Cm.  .........................................................................................................................................................................  10¹²-10¹⁵

OPTICAL

Optic axial angle (2V) degrees  ..............................................................................................................................................................  38-47

Orientation of optic plane to plane of symmetry  ................................................................................................................  Perpendicular

Indexes of refraction .........         
...................................................................................................................................................  1.552-1.570

                                                               
β....................................................................................................................................................  1.582-1.607

                                                               
ɤ....................................................................................................................................................  1.588-1.611