Chart of Mica Qualities

Detail your services

SUPER FINE

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

INDICATOR OF COMPARITIVE VALUE  100
V-2
NMS
Clear& Slightly Stained
 

INDICATOR OF COMPARITIVE VALUE 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.
 

INDICATOR OF COMPARITIVE VALUE 45
V-4
NMG
GOOD STAINED

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

INDICATOR OF COMPARITIVE VALUE 32

RADIO TUBE QUALITY

V-5
NMSA
STAINED A

High quality radio tube spacers, lowest quality for used for small capacitors
 

INDICATOR OF COMPARITIVE VALUE 14
V-6
NMSB
STAINED B

INDICATOR OF COMPARITIVE VALUE 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.
 

INDICATOR OF COMPARITIVE VALUE 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